Objective:To investigate the ability of the methanolic extract of pineapple peel to modulate alcohol-induced lipid peroxidation,changes in catalase activities and hepatic biochemical marker levels in blood plasma.Meth...Objective:To investigate the ability of the methanolic extract of pineapple peel to modulate alcohol-induced lipid peroxidation,changes in catalase activities and hepatic biochemical marker levels in blood plasma.Methods:Oxidative stress was induced by oral administration of ethanol(20%w/v) at a dosage of 5 niL/kg bw in rats.After 28 days of treatment,the rats were fasted overnight and sacrificed by cervical dislocation.Blood was collected with a 2 mL syringe by cardiac puncture and was centrifuged at 3000 rpm for 10 min.The plasma was analyzed to evaluate malondialdehyde(MDA),catalase activity,aspartate aminotransferase(AST),alkaline phosphatase(ALP) and alanine aminotransferase(ALT) concentrations.Results:Administration of alcohol caused a drastic increase(87.74%) in MDA level compared with the control.Pineapple peel extract significantly reduced the MDA level by 60.16%at 2.S mL/kg bw.Rats fed alcohol only had the highest catalase activity,treatment with pineapple peel extract at 2.5 mL/kg bw however, reduced the activity.Increased AST,ALP and ALT activities were observed in rats fed alcohol only respectively,treatment with pineapple peel extract drastically reduced their activities. Conclusions:The positive modulation of lipid peroxidation,catalase activities as well as hepatic biomarker levels of blood plasma by the methanolic extract of pineapple peels under alcoholinduced oxidative stress is an indication of its protective ability in the management of alcoholinduced toxicity.展开更多
Both geoparks and geosites are unique geological features of spectacular importance to earth science (global scientific importance) and the surrounding community.The Oldonyo Lengai(The God for the Maasai people and un...Both geoparks and geosites are unique geological features of spectacular importance to earth science (global scientific importance) and the surrounding community.The Oldonyo Lengai(The God for the Maasai people and unique active felsic magmatism)展开更多
Objective:To investigate the ability of the methanolic extract of pineapple peel to attenuate alcohol-induced changes in total phospholipids and lipid peroxidation in brain tissues. Methods:Oxidative stress was induce...Objective:To investigate the ability of the methanolic extract of pineapple peel to attenuate alcohol-induced changes in total phospholipids and lipid peroxidation in brain tissues. Methods:Oxidative stress was induced by oral administration of ethanol(20%w/v) at a dosage of 5 mL/kg bw in rats.After 28 days of treatment,the rats were fasted overnight and sacrificed by cervical dislocation.Brain tissues were assayed for total phospholipid(TP) content and malondialdehyde(MDA).Results:Administration of alcohol significantly caused a reduction in TP content.Treatment with pineapple peel extract significantly increased the TP content. Significant high levels of MDA was observed in alcohol-fed rats,treatment with pineapple peel extract significantly reduced the MDA levels.Conclusions:Results obtained from this study indicates that pineapple peel extract protects against alcohol-induced changes in total phospholipids and lipid peroxidation in brain tissues.展开更多
In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and...In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and therefore must not be treated separately. Minkowski adopted four-dimensional space-time frames (4-d s-t frames), which indirectly revealed the dependency of space and time with the addition of a constraint for an event interval. We are not able to visualize 4-d s-t frames. Since space and time are inseparable, three-dimensional space-time frames (3-d s-t frames) can be constructed by embedding time into space to directly show the interdependency of space and time. Time contraction and length contraction can also be depicted graphically using 3-d s-t frames. We have much better understanding reality of space and time in 3-d s-t frames. This will lead to Contextual Reality for better understanding the universe.展开更多
The effect of aqueous extract of the leaves of Chromolaena odorata on body weight, organ sizes, lipid profiles and atherogenic indices was investigated in normal and sub-chronic salt-loaded rats. The normal and treatm...The effect of aqueous extract of the leaves of Chromolaena odorata on body weight, organ sizes, lipid profiles and atherogenic indices was investigated in normal and sub-chronic salt-loaded rats. The normal and treatment control groups were fed 100% of commercial feed, while the test control, reference and test treatment groups received an 8% salt-loaded diet. The extract (at 100 and 200 mg/kg body weight) and moduretics (at 1 mg/kg body weight) were orally administered daily. The normal and test control groups orally received appropriate volumes of water. The extract was screened for bioactive components using gas chromatography-coupled-flame ionization detector. The main glycosides, saponins, allicins, alkaloids, benzoic acid derivatives, terpenes and lignans detected were arbutin, avenacin B-1 (and avenacin A-1), diallyl thiosulphinate, lupanine, ferulic acid (and vanillic acid), limonene and retusin, respectively. Compared to test control, the extract dose-dependently, significantly (P 0.05) lowered the heart size, plasma levels of triglyceride, total density lipoprotein, very low density lipoprotein, low density lipoprotein and non-high density lipoprotein cholesterol and atherogenic indices (cardiac risk ratio, atherogenic coefficient and atherogenic index of plasma). It also significantly increased plasma high density lipoprotein level. These results suggest a protective mechanism of the extract against hypertension induced cardiomegaly and dyslipidemia, thus suggesting that this may underlie its antihypertensive action.展开更多
From 2012 to 2015, we measured surface ozone, NOx, NO2, and NO levels at three urban sites (Mapipa, Ubungo, and Posta) and two suburban sites (Kunduchi and Vijibweni) in the city of Dar es Salaam and in the village of...From 2012 to 2015, we measured surface ozone, NOx, NO2, and NO levels at three urban sites (Mapipa, Ubungo, and Posta) and two suburban sites (Kunduchi and Vijibweni) in the city of Dar es Salaam and in the village of Mwetemo, a rural area of Bagamoyo, Tanzania. The average hourly O3 concentrations at all sites were between 9 ppb and 30 ppb during our sampling periods. O3 levels at suburban sites were generally higher than at urban sites. The average hourly concentrations in Dar es Salaam were 10 - 32 ppb, while in Bagamoyo they were 9 - 15 ppb. We observed a strong diurnal variation in Dar es Salaam while measurements from Bagamoyo showed little variation. At Dar es Salaam, the surface O3 concentrations increased from their minimum level at sunrise (around 6:00 a.m.) to a maximum in the late afternoon (around 4:00 p.m.), and then decreased toward 11:00 p.m. Another secondary ozone peak appeared between midnight and ~4:00 a.m., after which the surface ozone concentrations decreased to a minimum around 7:00 a.m. NO2 concentrations were higher at the urban sites of Ubungo and Posta, and their weekly average NO2 concentrations were 246 ppb and 118 ppb, respectively. Weekly average NOx concentrations ranged from 39.4 ppb at the Kunduchi site (suburban) to 738 ppb at the Ubungo site (urban). To our knowledge, there were few continuous measurements of ozone and nitrogen oxides concentrations in Tanzania. Since high NOx concentrations were observed, continuous air quality monitoring and effective air pollution control measures are required in Dar es Salaam to prevent further deterioration of air quality and limit the possible negative impacts on humans and vegetation.展开更多
Rivers are important for aquatic biodiversity. Anthropogenic activities degrade rivers and decrease their capacity to offer ecosystem services. This study used macroinvertebrates to assess the impact of anthropogenic ...Rivers are important for aquatic biodiversity. Anthropogenic activities degrade rivers and decrease their capacity to offer ecosystem services. This study used macroinvertebrates to assess the impact of anthropogenic activities on the Pinyinyi River during dry and wet season. Abundance of macroinvertebrates, average score per taxon and Shannon Weiner Species Diversity Index were used to state the ecological status of Pinyinyi River. Because the abundance of macroinvertebrates can be affected by change in water quality, some of the physicochemical parameters were also measured. A macroinvertebrates hand net is used to collect the macroinvertebrates per sampling point. DO, temperature, pH, turbidity and TDS were measured in-situ using HI-9829 Multiparameter and BOD was measured in the laboratory using Oxydirect levibond method. A total of 164 macroinvertebrates were collected and identified from Pinyinyi River during dry and wet season. They belong to 13 families. The most abundant taxa were mosquito larva, Diptera (41.07%) and aquatic caterpillar, Lepidoptera (23.21%) during dry season representing about 64.28% of the total macroinvertebrates whereas the least abundant taxa were pouch snail (16.07%) and dragonflies, Odonata (19.64%) during dry season representing about 35.72% of the total macroinvertebrates. The most abundant taxa collected during wet season were aquatic earthworm, haplotaxida (19.44%), midges, Diptera (17.59%), black flies, Diptera (15.74%) and creeping water bugs, hemiptera (12.96%) whereas the least abundant were pigmy back swimmers, hemiptera (2.78%), snail (3.7%), predacious dividing beetle (4.63%) and coleopteran (4.63%). Average Score per taxon of Pinyinyi River during dry season was 5.25 and 3.6 during wet season. The Shannon Weiner Species Diversity Index was 1.318 during dry season and 2.138 during wet season. Based on the score, Pinyinyi River is moderately polluted during dry season and seriously polluted during wet season. Based on index, Pinyinyi River has low diversity of macroinvertebrates during dry season and highly in diversity of macroinvertebrates during wet season. Moreover, it was found that, agricultural activities, livestock keeping, bathing and washing alter physicochemical parameters of Pinyinyi River and hence change the abundance of macroinvertebrates as well as the quality of water. The study, therefore, recommends that the source of pollutants should be controlled and the river regularly monitored by the relevant authorities.展开更多
Animals rely on olfaction to detect and process invaluable chemical information about their environment.For olfaction to function,chemicals must first be detected,which leads to the activation of signal-transduction p...Animals rely on olfaction to detect and process invaluable chemical information about their environment.For olfaction to function,chemicals must first be detected,which leads to the activation of signal-transduction pathways at the peripheral olfactory organ.As the olfactory system is in direct contact with the environment,the system is constantly vulnerable to damage by contaminants entering the atmosphere or hydrosphere.Contaminants may have a variety of effects,including disrupting olfactory signals generated during chemical detection,or altering numerous targets along the signal transduction pathway.With any impairment of chemical detection,animals may be unable to rely on olfaction to make correct decisions about their environment and thus their fitness.While other reviews have focussed on olfactory toxicology in general,here we specifically explore how contaminants may affect the signal-transduction pathways at various points and link those changes to olfactory functionality across vertebrates with a focus on fishes.展开更多
The leaves of Tridax procumbens were screened for the presence of bioactive molecules. They had high flavonoids, alkaloids, hydroxycinnamates, tannins and phytosterols, moderate benzoic acid derivatives and lignans, a...The leaves of Tridax procumbens were screened for the presence of bioactive molecules. They had high flavonoids, alkaloids, hydroxycinnamates, tannins and phytosterols, moderate benzoic acid derivatives and lignans, and low carotenoids contents. Thirty nine known alkaloids (mainly akuammidine, 68.756%), twenty three known flavonoids (mainly 17.593% kaempferol and 12.538% (-)-epicatechin), five known carotenoids (mainly lutein, 62.608%), four known benzoic acid derivatives (mainly ferulic acid, 46.091%), two phytosterols (mainly stigmasterol, 80.853%) and six known lignans (mainly galgravin, 77.326%) were detected. Also detected were caffeic acid and tannic acid. The medicinal properties of the flavonoids, phytosterols, alkaloids, tannins, hydroxicinnamates, carotenoids, benzoic acid derivatives and lignans that were present in the leaves were discussed herein and proposed to be explored for their potential medicinal values. The great number of potentially active nutrients and their multifunctional properties make Tridax procumbens a perfect candidate for the production of health-promoting food and food supplements.展开更多
In classical physics, time and space are absolute and independent, so time and space can be treated separately. However, in modern physics, time and space are relative and dependent: time and space must be treated tog...In classical physics, time and space are absolute and independent, so time and space can be treated separately. However, in modern physics, time and space are relative and dependent: time and space must be treated together. In 4-d s-t frames, we treat time and space independently, then add a constraint to link them together. In teaching, there is a big gap between classical and modern physics. We hope that we are able to find a frame connecting them to make learning simpler. 3-d s-t frame is the best candidate to serve this purpose: time and space are able to be treated dependently by defining the unit of time as T and the unit of space as λ in this frame. Furthermore, the ratio, λ/T, is the velocity, c, of the medium. This paper shows the equivalence between a 4-d s-t frame and a 3-d s-t frame by properly converting coordinates of two frames.展开更多
Objective:To investigate the incidence of human cytomegalo virus(HCMV) in pregnant women.Methods: One hundred and twenty two(122) blood samples and 80 umbilical cord fluids were tested for IgG and IgM respectively usi...Objective:To investigate the incidence of human cytomegalo virus(HCMV) in pregnant women.Methods: One hundred and twenty two(122) blood samples and 80 umbilical cord fluids were tested for IgG and IgM respectively using the enzyme linked immunosorbent assay(ELISA).Results:Of the 122 samples screened for IgG and IgM only 56(47.1%) tested positive for IgG while 63(52.9%) were positive for IgM with 3 samples non-specific.Pregnant women with signs of normal pregnancy made up 60%of the positive results while 20%had a history of ectopic pregnancy and 20%with a history of miscarriages.Of the total of 80 umbilical cord fluids tested,only 59(73.8) tested positive.Eleven of the selected 40 umblical cord fluid was positive to IgG to human cytomegalovirus along with mother and child.Antibody titration result gave diagnostic titre for both IgG and IgM from the 40 umbilical cord fluids.There was a significant relationship between mother,child and umbilical cord fluids(χ~2 = 1.360,CI = 99%,P = 0.568).Conclusion:There could be a possible neonatal infection,and the infection is common among toddlers and children of pre-school age.展开更多
One of the major problems of agricultural soils in the tropical regions of the Pacific is the low organic matter content.Because of the hot and humid environment,the soil organic matter(SOM)is minimal due to rapid dec...One of the major problems of agricultural soils in the tropical regions of the Pacific is the low organic matter content.Because of the hot and humid environment,the soil organic matter(SOM)is minimal due to rapid decomposition.Composted organic material is being applied on agricultural fields as an amendment to provide nutrients and enhance the organic matter content for improving the physical and chemical properties of the cultivated soils.In addition land application of composted material as a fertilizer source effectively disposes of wastes that otherwise are buried in landfills.In our soil program at the University of Guam,we are evaluating the use of organic material as an alternative to synthetic fertilizers.Its goal is to develop management strategies and use available resources for improving crop production while conserving resources and preserving environmental quality.Our case study project is designed to improve soil fertility status by using composted organic wastes and assessing how the nitrogen and other essential nutrients contribute to long-term soil fertility and crop productivity without application of synthetic fertilizers.In our pilot project,compost is produced from wood chips,grinded typhoon debris mixed with animal manure,fish feed,shredded paper and other organic wastes.Mature compost is then applied on the field at the rates of 0,5,10 and 20 t/ha as a soil amendment on the eroded cobbly soils of southern Guam.Corn is planted and monitored for growth performance and yield.The effect of land application of composted material on the SOM content and overall soil quality indices are being evaluated in this pilot study.展开更多
Objective:Chlamydia is made of organism responsible for respiratory as well as genital infections with very serious sequelae.In Nigeria there is paucity of information regards relative frequencies of Chlamydia infecti...Objective:Chlamydia is made of organism responsible for respiratory as well as genital infections with very serious sequelae.In Nigeria there is paucity of information regards relative frequencies of Chlamydia infection of which this study reports in North West zone of Nigeria.Methods:Three hundred and thirty three(333) blood samples were collected from individuals attending various clinics in North West zone of Nigeria and tested for Chlamydia complement fixing antibody.Swabs collected from positive patients were re-tested using the Romanowsky -Giemsa staining technique.Statistical analysis were carried out in epi-info epidemiological software package.Results:From the total of 333 samples collected and tested for Chlamydia complement fixing antibody (CCFA) only 287(86%) were positive.The culture showed that 215(75%) were positive for Chlamydia trachomatis while only 135(47%) were positive for Chlamydia pneumoniae.Seventy one(71) females had symptomatic infection while 31 males were symptomatic.Of the 104 individuals who were asymptomatic 67 were females while 92 were males.Of the 31 symptomatic males were 22 positive to Chlamydia pneumoniae and the symptoms being that of respiratory syndrome while 9 had difficulty urinating.All the symptomatic women had symptoms resembling that of the pelvic inflammatory disease(PID) and vaginal discharge. Age groups 31-35 had the highest positive samples while the extreme ages had the lowest number of positive individuals and also the lowest number of samples.The number of samples as well as the positive results were validated using the epi-info statistical package version 3.4.1.There was no significant difference in the number of samples from both males and females(χ~2=1.360,CI = 99%).Conclusion:A high percentage of positive result as validated by statistical analysis shows that Chlamydia infections are endemic in the population and efforts should be made to screen for the organism to avoid the " silent epidemics".展开更多
A major environmental concern due to dispersal of industrial and urban wastes generated by human activities is the contamination of soil. The release of heavy metals into the terrestrial ecosystem is a major problem. ...A major environmental concern due to dispersal of industrial and urban wastes generated by human activities is the contamination of soil. The release of heavy metals into the terrestrial ecosystem is a major problem. Accumulation of heavy metals in environment and particularly in soil is a serious environmental concern, as the accumulated heavy metal ions can find their way into living organisms via contamination of ground water or food chain. This praxis urgently requires and demands governmental regulations in India. Two samples of sludge were collected from Banthar Industrial Pollution Control Company (BIPCC), UP State Industrial Development Corporation (UPSIDC), Leather Technology Park, Banthar, Unnao, India. In the present study, the phytoremediation potential of Catharanthus roseus, a valued medicinal plant, with respect to chromium has been analyzed. C. roseus was shown to absorb up to about 38% of the amount of Cr present in primary and secondary sludge amended soil through roots and accumulate it to about 22% in leaves. Effect of chromium concentration on the status of antioxidant enzyme peroxidase (POD) and detoxification enzyme glutathione-S-transferase (GST) from C. roseus leaves was also observed and determined. Increased expressions of POD and GST were observed on native PAGE under stress conditions as compared to control. C. roseus can well tolerate low amounts of chromium (and accumulate it to about 22% in leaves) and can, thus, prove useful in the reclamation and remediation of chromium contaminated soil and land.展开更多
<p style="margin-left:10.0pt;"> <br /> </p> <p style="margin-left:10.0pt;"> <span>The coenzyme B<sub>12</sub> dependent glutamate mutase is composed of two...<p style="margin-left:10.0pt;"> <br /> </p> <p style="margin-left:10.0pt;"> <span>The coenzyme B<sub>12</sub> dependent glutamate mutase is composed of two apoenzyme proteins subunits;S and E<sub>2</sub>, which while either fused or separate assemble with coenzyme B<sub>12</sub> to form an active holoenzyme (E<sub>2</sub>S<sub>2</sub>-B<sub>12</sub>) for catalyzing the reversible isomerization between (<i>S</i>)-glutamate and (2<i>S</i>, 3<i>S</i>)-3-methylas</span><span>- </span><span>partate. In order to assay the activity of glutamate mutase by UV spectrophotometry, this reaction is often coupled with methylaspartase which deaminates (2<i>S</i>, 3<i>S</i>)-3-methylaspartate to form mesaconate (<i>λ</i><sub>max</sub> = 240 nm, </span><span>Ɛ</span><sub><span>240</span></sub><span> = 3.8 mM<sup>-1</sup>·cm<sup>-1</sup>). The activities of different reconstitutions of glutamate mu<span>tase from separate apoenzyme components S and E in varied amount</span></span><span>s</span><span> of </span><span>coenzyme B<sub>12</sub> and adenosylpeptide B<sub>12</sub> as cofactors were measured by this assay and used to reveal the binding properties of the cofactor by the Michaelis</span><span>- </span><span>Menten Method. The values of <i>K<sub>m</sub></i> for coenzyme B<sub>12</sub> in due to reconstitutions of holoenzyme in 2, 7 and 14 S: E were determined as;1.12 ± 0.04 μM, 0.7 ± 0.05 μM and 0.52 ± 0.06 μM, respectively, so as those of adenosylpeptide B<sub>12</sub>;1.07 ± 0.04 μM and 0.35 ± 0.05 μM as obtained from respective 2 and 14 S: E compositions of holoenzyme. Analysis of these kinetics results curiously as<span>sociate</span></span><span>s</span><span> the increasing affinity of cofactors to apoenzyme with</span><span> </span><span>increased amount of component S used in reconstituting holoenzyme from separate</span><span> apoenzyme components and cofactor.</span><span> Moreover, in these studies a new method for assaying the activity of glutamate mutase was developed, whereby glutamate mutase activity is measured via depletion of NADH (<i>λ</i><sub>max</sub> = 340 nm, </span><span>Ɛ</span><sub><span>340</span></sub><span> = 6.3 mM<sup>-1</sup>·cm<sup>-1</sup>) as determined by UV spectrophotometry after addition of (2<i>S</i>,<span> 3<i>S</i>)-3-methylaspartate and pyruvate to a mixture of E<sub>2</sub>S<sub>2</sub>-B<sub>12</sub> and two auxiliary </span><span>holoenzymes system;pyridoxal-5-phosphate dependent glutamate-pyruvate </span><span>aminotransferase and N</span>ADH dependent (<i>R</i>)-2-hydroxyglutarate dehydrogenas<span>e. The activity of glutamate-pyruvate aminotransferase was relatively complete recovered upon the addition of (<i>S</i>)-glutamate and pyruvate to the mixtures of hologlutamate-pyruvate aminotransferase and (<i>R</i>)-2-hydroxylglutarate</span> dehydrogenase which were incubated with each putative inhibitor of glutamate mutase. Additionally, the new assay was used to determine the kinetic constants of (2<i>S</i>, 3<i>S</i>)-3-methylaspartate in the reaction of glutamate mutase as <i>K</i><sub>m</sub>= 7 ± 0.07 mM and <i>k</i><sub>cat</sub>= 0.54 ± 0.6 s<sup>-1</sup>. Application of Briggs-Haldane formula allowed the calculation of an equilibrium constant of the reversible isomerization, <i>K</i><sub>eq</sub> = [(<i>S</i>)-glutamate] × [(2<i>S</i>, 3<i>S</i>)-3-methylaspartate]<sup>-1</sup> = 16, where the kinetic constants of (<i>S</i>)-glutamate were determined by the standard methylaspartase coupled assay.<span></span></span> </p> <p> <br /> </p>展开更多
Six hundred and fifty-eight specimens of the Clariidae were collected from seven localities in the Lake Victoria basin and the Malagarasi wetland, Tanzania. A total of three hundred unadjusted morphometric measurement...Six hundred and fifty-eight specimens of the Clariidae were collected from seven localities in the Lake Victoria basin and the Malagarasi wetland, Tanzania. A total of three hundred unadjusted morphometric measurements and meristic counts were analysed with the aim of assessing the adequacy of morphometric technique to delineate the clariid species occurring in theLake Victoriabasin. Results showed that morphometrics augmented by multivariate analysis (PCA, DCA and cluster analysis) amalgamated the clariid fishes into three groups, the?Clarias alluaudi/C. werneri,?C. gariepinus/C. liocephalus?andClariallabes petricola. Although other workers have used this technique, the present study concluded that, standing alone morphometrics is not a substitute for external morphology in the identification of clariid fish species, as it failed to separate the clariids into their respective taxonomic species. The technique, however, insinuates the regressional morphological relationships among the clariids occurring in the Lake Victoria basin.展开更多
Malaria has continued to be a health and economic problem in Africa and the world at large. Many anti-malarial drugs have been rendered ineffective due to the emergence of resistant strains of Plamodium falciparum. A ...Malaria has continued to be a health and economic problem in Africa and the world at large. Many anti-malarial drugs have been rendered ineffective due to the emergence of resistant strains of Plamodium falciparum. A key malaria parasite enzyme in glycolytic pathway, P. falciparum lactate dehydrogenase (PfLDH) is specially targeted for anti-malarial drugs development. Thus, the aim of this investigation was to determine the in silico inhibition effects of antimalarial compounds from Hoslundia opposita Vahl. namely hoslundin, hoslundal and hoslunddiol on PfLDH enzyme. The compounds were docked to the three-dimensional structure of PfLDH as enzyme using AutoDock Vina in PyRx virtual screening software. Binding affinity and position of the inhibitors were evaluated using PyMol software. The PfLDH enzyme showed two binding sites: the cofactors binding site (Site A) and secondary binding site (Site B). In the absence of the cofactor all ligands showed higher affinity than NADH, and were bound to the cofactors binding site (Site A). When docked in the presence of the cofactor, site B was the preferred binding site. Binding to cofactor site with higher binding energy than NADH suggests that these ligands could act as preferential competitive inhibitors of PfLDH. However, the binding to site B also suggests that they may be non-competitive allosteric inhibitors. Amino acid residues Gly99, Asn140, Phe100 and Thr97 were indicated to form hydrogen bonds with Hoslundin. Hoslunddiol showed hydrogen bonding with Thr97 and Met30, while Hoslundal formed hydrogen bond with Thr101 and Asn140.展开更多
Fundamental units of measurements are kilograms, meters, and seconds—in regards to mass length, and time. All other measurements in mechanical quantities including kinetic quantities and dynamic quantities are called...Fundamental units of measurements are kilograms, meters, and seconds—in regards to mass length, and time. All other measurements in mechanical quantities including kinetic quantities and dynamic quantities are called derived units. These derived units can be expressed in terms of fundamental units, such as acceleration, area, energy, force, power, velocity and volume. Derived quantities will be referred to as time, length, and mass. In order to explain that fundamental units are not equivalent with fundamental quantities, we need to understand the contraction of time and length in Special Relativity. If we choose the velocity of light as fundamental quantity and length and time as derived quantities, then we are able to construct three-dimensional space-time frames. Three-dimensional space-time frames representing time with polar coordination, time contraction and length contraction can be shown graphically.展开更多
The Current Standard Model of the Universe asserts that the universe is generated from a single Big Bang event followed by inflation. There is no center to this universe, hence, no preferential reference frame to desc...The Current Standard Model of the Universe asserts that the universe is generated from a single Big Bang event followed by inflation. There is no center to this universe, hence, no preferential reference frame to describe the motions of celestial objects. We propose a new, Shell Model of the Universe, which contends that the universe is created from multiple, concentric big bangs. Accordingly, that origin presents itself as a unique, preferential reference frame, which furnishes the simplest description of the motions of galaxies in the cosmos. This is similar in manner to how planetary motion is more straightforwardly described via a sun-centered Solar System rather than an earth-centered one. The appeal of the Shell Model of the Universe lies in its simplistic ability to resolve the paradox of quasars, explain the variability in Hubble’s Constant, and solve the problematic accelerated expansion of the universe.展开更多
Meighan Wetland and its surroundings have undergone many changes in recent years.This study aims to monitor and predict land use changes using the land change model (LCM) module in the Meighan wetland.Land Sat images ...Meighan Wetland and its surroundings have undergone many changes in recent years.This study aims to monitor and predict land use changes using the land change model (LCM) module in the Meighan wetland.Land Sat images of years 2000,2007 and 2015 were used to produce digital land use maps.The images were classified into seven classes including;Salt lake,Agriculture,Rangeland,Manmade,Wastewater,Wetland and Mine areas.The LCM module in Idrisi GIS software was used to analyze the land use changes for predicting the land uses status in 2015,based on artificial neural network (ANN) and Markov Chain analysis.The ANN was trained with various influencing factors including;distance from road,distance from manmade areas,distance from land changed edge,distance from stream,elevation and slope.The results indicated that 1663.88 ha of the rangeland cover and 715.68 ha of the salt lake cover have been degraded during the 2000-2015 period.Furthermore,the wetland,mine,wastewater and manmade degradation are increased to 724 ha,335 ha,37 ha and 270 ha in comparison to initial land conditions.Also,the result shows that rangeland and salt lake areas will decrease in the year 2030 compare to 2015,while,wetland,mine and manmade land changes may increase.展开更多
文摘Objective:To investigate the ability of the methanolic extract of pineapple peel to modulate alcohol-induced lipid peroxidation,changes in catalase activities and hepatic biochemical marker levels in blood plasma.Methods:Oxidative stress was induced by oral administration of ethanol(20%w/v) at a dosage of 5 niL/kg bw in rats.After 28 days of treatment,the rats were fasted overnight and sacrificed by cervical dislocation.Blood was collected with a 2 mL syringe by cardiac puncture and was centrifuged at 3000 rpm for 10 min.The plasma was analyzed to evaluate malondialdehyde(MDA),catalase activity,aspartate aminotransferase(AST),alkaline phosphatase(ALP) and alanine aminotransferase(ALT) concentrations.Results:Administration of alcohol caused a drastic increase(87.74%) in MDA level compared with the control.Pineapple peel extract significantly reduced the MDA level by 60.16%at 2.S mL/kg bw.Rats fed alcohol only had the highest catalase activity,treatment with pineapple peel extract at 2.5 mL/kg bw however, reduced the activity.Increased AST,ALP and ALT activities were observed in rats fed alcohol only respectively,treatment with pineapple peel extract drastically reduced their activities. Conclusions:The positive modulation of lipid peroxidation,catalase activities as well as hepatic biomarker levels of blood plasma by the methanolic extract of pineapple peels under alcoholinduced oxidative stress is an indication of its protective ability in the management of alcoholinduced toxicity.
文摘Both geoparks and geosites are unique geological features of spectacular importance to earth science (global scientific importance) and the surrounding community.The Oldonyo Lengai(The God for the Maasai people and unique active felsic magmatism)
文摘Objective:To investigate the ability of the methanolic extract of pineapple peel to attenuate alcohol-induced changes in total phospholipids and lipid peroxidation in brain tissues. Methods:Oxidative stress was induced by oral administration of ethanol(20%w/v) at a dosage of 5 mL/kg bw in rats.After 28 days of treatment,the rats were fasted overnight and sacrificed by cervical dislocation.Brain tissues were assayed for total phospholipid(TP) content and malondialdehyde(MDA).Results:Administration of alcohol significantly caused a reduction in TP content.Treatment with pineapple peel extract significantly increased the TP content. Significant high levels of MDA was observed in alcohol-fed rats,treatment with pineapple peel extract significantly reduced the MDA levels.Conclusions:Results obtained from this study indicates that pineapple peel extract protects against alcohol-induced changes in total phospholipids and lipid peroxidation in brain tissues.
文摘In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and therefore must not be treated separately. Minkowski adopted four-dimensional space-time frames (4-d s-t frames), which indirectly revealed the dependency of space and time with the addition of a constraint for an event interval. We are not able to visualize 4-d s-t frames. Since space and time are inseparable, three-dimensional space-time frames (3-d s-t frames) can be constructed by embedding time into space to directly show the interdependency of space and time. Time contraction and length contraction can also be depicted graphically using 3-d s-t frames. We have much better understanding reality of space and time in 3-d s-t frames. This will lead to Contextual Reality for better understanding the universe.
文摘The effect of aqueous extract of the leaves of Chromolaena odorata on body weight, organ sizes, lipid profiles and atherogenic indices was investigated in normal and sub-chronic salt-loaded rats. The normal and treatment control groups were fed 100% of commercial feed, while the test control, reference and test treatment groups received an 8% salt-loaded diet. The extract (at 100 and 200 mg/kg body weight) and moduretics (at 1 mg/kg body weight) were orally administered daily. The normal and test control groups orally received appropriate volumes of water. The extract was screened for bioactive components using gas chromatography-coupled-flame ionization detector. The main glycosides, saponins, allicins, alkaloids, benzoic acid derivatives, terpenes and lignans detected were arbutin, avenacin B-1 (and avenacin A-1), diallyl thiosulphinate, lupanine, ferulic acid (and vanillic acid), limonene and retusin, respectively. Compared to test control, the extract dose-dependently, significantly (P 0.05) lowered the heart size, plasma levels of triglyceride, total density lipoprotein, very low density lipoprotein, low density lipoprotein and non-high density lipoprotein cholesterol and atherogenic indices (cardiac risk ratio, atherogenic coefficient and atherogenic index of plasma). It also significantly increased plasma high density lipoprotein level. These results suggest a protective mechanism of the extract against hypertension induced cardiomegaly and dyslipidemia, thus suggesting that this may underlie its antihypertensive action.
文摘From 2012 to 2015, we measured surface ozone, NOx, NO2, and NO levels at three urban sites (Mapipa, Ubungo, and Posta) and two suburban sites (Kunduchi and Vijibweni) in the city of Dar es Salaam and in the village of Mwetemo, a rural area of Bagamoyo, Tanzania. The average hourly O3 concentrations at all sites were between 9 ppb and 30 ppb during our sampling periods. O3 levels at suburban sites were generally higher than at urban sites. The average hourly concentrations in Dar es Salaam were 10 - 32 ppb, while in Bagamoyo they were 9 - 15 ppb. We observed a strong diurnal variation in Dar es Salaam while measurements from Bagamoyo showed little variation. At Dar es Salaam, the surface O3 concentrations increased from their minimum level at sunrise (around 6:00 a.m.) to a maximum in the late afternoon (around 4:00 p.m.), and then decreased toward 11:00 p.m. Another secondary ozone peak appeared between midnight and ~4:00 a.m., after which the surface ozone concentrations decreased to a minimum around 7:00 a.m. NO2 concentrations were higher at the urban sites of Ubungo and Posta, and their weekly average NO2 concentrations were 246 ppb and 118 ppb, respectively. Weekly average NOx concentrations ranged from 39.4 ppb at the Kunduchi site (suburban) to 738 ppb at the Ubungo site (urban). To our knowledge, there were few continuous measurements of ozone and nitrogen oxides concentrations in Tanzania. Since high NOx concentrations were observed, continuous air quality monitoring and effective air pollution control measures are required in Dar es Salaam to prevent further deterioration of air quality and limit the possible negative impacts on humans and vegetation.
文摘Rivers are important for aquatic biodiversity. Anthropogenic activities degrade rivers and decrease their capacity to offer ecosystem services. This study used macroinvertebrates to assess the impact of anthropogenic activities on the Pinyinyi River during dry and wet season. Abundance of macroinvertebrates, average score per taxon and Shannon Weiner Species Diversity Index were used to state the ecological status of Pinyinyi River. Because the abundance of macroinvertebrates can be affected by change in water quality, some of the physicochemical parameters were also measured. A macroinvertebrates hand net is used to collect the macroinvertebrates per sampling point. DO, temperature, pH, turbidity and TDS were measured in-situ using HI-9829 Multiparameter and BOD was measured in the laboratory using Oxydirect levibond method. A total of 164 macroinvertebrates were collected and identified from Pinyinyi River during dry and wet season. They belong to 13 families. The most abundant taxa were mosquito larva, Diptera (41.07%) and aquatic caterpillar, Lepidoptera (23.21%) during dry season representing about 64.28% of the total macroinvertebrates whereas the least abundant taxa were pouch snail (16.07%) and dragonflies, Odonata (19.64%) during dry season representing about 35.72% of the total macroinvertebrates. The most abundant taxa collected during wet season were aquatic earthworm, haplotaxida (19.44%), midges, Diptera (17.59%), black flies, Diptera (15.74%) and creeping water bugs, hemiptera (12.96%) whereas the least abundant were pigmy back swimmers, hemiptera (2.78%), snail (3.7%), predacious dividing beetle (4.63%) and coleopteran (4.63%). Average Score per taxon of Pinyinyi River during dry season was 5.25 and 3.6 during wet season. The Shannon Weiner Species Diversity Index was 1.318 during dry season and 2.138 during wet season. Based on the score, Pinyinyi River is moderately polluted during dry season and seriously polluted during wet season. Based on index, Pinyinyi River has low diversity of macroinvertebrates during dry season and highly in diversity of macroinvertebrates during wet season. Moreover, it was found that, agricultural activities, livestock keeping, bathing and washing alter physicochemical parameters of Pinyinyi River and hence change the abundance of macroinvertebrates as well as the quality of water. The study, therefore, recommends that the source of pollutants should be controlled and the river regularly monitored by the relevant authorities.
基金support by a grant from Natural Sciences and Engineering Research Council to K.B.T.
文摘Animals rely on olfaction to detect and process invaluable chemical information about their environment.For olfaction to function,chemicals must first be detected,which leads to the activation of signal-transduction pathways at the peripheral olfactory organ.As the olfactory system is in direct contact with the environment,the system is constantly vulnerable to damage by contaminants entering the atmosphere or hydrosphere.Contaminants may have a variety of effects,including disrupting olfactory signals generated during chemical detection,or altering numerous targets along the signal transduction pathway.With any impairment of chemical detection,animals may be unable to rely on olfaction to make correct decisions about their environment and thus their fitness.While other reviews have focussed on olfactory toxicology in general,here we specifically explore how contaminants may affect the signal-transduction pathways at various points and link those changes to olfactory functionality across vertebrates with a focus on fishes.
文摘The leaves of Tridax procumbens were screened for the presence of bioactive molecules. They had high flavonoids, alkaloids, hydroxycinnamates, tannins and phytosterols, moderate benzoic acid derivatives and lignans, and low carotenoids contents. Thirty nine known alkaloids (mainly akuammidine, 68.756%), twenty three known flavonoids (mainly 17.593% kaempferol and 12.538% (-)-epicatechin), five known carotenoids (mainly lutein, 62.608%), four known benzoic acid derivatives (mainly ferulic acid, 46.091%), two phytosterols (mainly stigmasterol, 80.853%) and six known lignans (mainly galgravin, 77.326%) were detected. Also detected were caffeic acid and tannic acid. The medicinal properties of the flavonoids, phytosterols, alkaloids, tannins, hydroxicinnamates, carotenoids, benzoic acid derivatives and lignans that were present in the leaves were discussed herein and proposed to be explored for their potential medicinal values. The great number of potentially active nutrients and their multifunctional properties make Tridax procumbens a perfect candidate for the production of health-promoting food and food supplements.
文摘In classical physics, time and space are absolute and independent, so time and space can be treated separately. However, in modern physics, time and space are relative and dependent: time and space must be treated together. In 4-d s-t frames, we treat time and space independently, then add a constraint to link them together. In teaching, there is a big gap between classical and modern physics. We hope that we are able to find a frame connecting them to make learning simpler. 3-d s-t frame is the best candidate to serve this purpose: time and space are able to be treated dependently by defining the unit of time as T and the unit of space as λ in this frame. Furthermore, the ratio, λ/T, is the velocity, c, of the medium. This paper shows the equivalence between a 4-d s-t frame and a 3-d s-t frame by properly converting coordinates of two frames.
文摘Objective:To investigate the incidence of human cytomegalo virus(HCMV) in pregnant women.Methods: One hundred and twenty two(122) blood samples and 80 umbilical cord fluids were tested for IgG and IgM respectively using the enzyme linked immunosorbent assay(ELISA).Results:Of the 122 samples screened for IgG and IgM only 56(47.1%) tested positive for IgG while 63(52.9%) were positive for IgM with 3 samples non-specific.Pregnant women with signs of normal pregnancy made up 60%of the positive results while 20%had a history of ectopic pregnancy and 20%with a history of miscarriages.Of the total of 80 umbilical cord fluids tested,only 59(73.8) tested positive.Eleven of the selected 40 umblical cord fluid was positive to IgG to human cytomegalovirus along with mother and child.Antibody titration result gave diagnostic titre for both IgG and IgM from the 40 umbilical cord fluids.There was a significant relationship between mother,child and umbilical cord fluids(χ~2 = 1.360,CI = 99%,P = 0.568).Conclusion:There could be a possible neonatal infection,and the infection is common among toddlers and children of pre-school age.
文摘One of the major problems of agricultural soils in the tropical regions of the Pacific is the low organic matter content.Because of the hot and humid environment,the soil organic matter(SOM)is minimal due to rapid decomposition.Composted organic material is being applied on agricultural fields as an amendment to provide nutrients and enhance the organic matter content for improving the physical and chemical properties of the cultivated soils.In addition land application of composted material as a fertilizer source effectively disposes of wastes that otherwise are buried in landfills.In our soil program at the University of Guam,we are evaluating the use of organic material as an alternative to synthetic fertilizers.Its goal is to develop management strategies and use available resources for improving crop production while conserving resources and preserving environmental quality.Our case study project is designed to improve soil fertility status by using composted organic wastes and assessing how the nitrogen and other essential nutrients contribute to long-term soil fertility and crop productivity without application of synthetic fertilizers.In our pilot project,compost is produced from wood chips,grinded typhoon debris mixed with animal manure,fish feed,shredded paper and other organic wastes.Mature compost is then applied on the field at the rates of 0,5,10 and 20 t/ha as a soil amendment on the eroded cobbly soils of southern Guam.Corn is planted and monitored for growth performance and yield.The effect of land application of composted material on the SOM content and overall soil quality indices are being evaluated in this pilot study.
文摘Objective:Chlamydia is made of organism responsible for respiratory as well as genital infections with very serious sequelae.In Nigeria there is paucity of information regards relative frequencies of Chlamydia infection of which this study reports in North West zone of Nigeria.Methods:Three hundred and thirty three(333) blood samples were collected from individuals attending various clinics in North West zone of Nigeria and tested for Chlamydia complement fixing antibody.Swabs collected from positive patients were re-tested using the Romanowsky -Giemsa staining technique.Statistical analysis were carried out in epi-info epidemiological software package.Results:From the total of 333 samples collected and tested for Chlamydia complement fixing antibody (CCFA) only 287(86%) were positive.The culture showed that 215(75%) were positive for Chlamydia trachomatis while only 135(47%) were positive for Chlamydia pneumoniae.Seventy one(71) females had symptomatic infection while 31 males were symptomatic.Of the 104 individuals who were asymptomatic 67 were females while 92 were males.Of the 31 symptomatic males were 22 positive to Chlamydia pneumoniae and the symptoms being that of respiratory syndrome while 9 had difficulty urinating.All the symptomatic women had symptoms resembling that of the pelvic inflammatory disease(PID) and vaginal discharge. Age groups 31-35 had the highest positive samples while the extreme ages had the lowest number of positive individuals and also the lowest number of samples.The number of samples as well as the positive results were validated using the epi-info statistical package version 3.4.1.There was no significant difference in the number of samples from both males and females(χ~2=1.360,CI = 99%).Conclusion:A high percentage of positive result as validated by statistical analysis shows that Chlamydia infections are endemic in the population and efforts should be made to screen for the organism to avoid the " silent epidemics".
文摘A major environmental concern due to dispersal of industrial and urban wastes generated by human activities is the contamination of soil. The release of heavy metals into the terrestrial ecosystem is a major problem. Accumulation of heavy metals in environment and particularly in soil is a serious environmental concern, as the accumulated heavy metal ions can find their way into living organisms via contamination of ground water or food chain. This praxis urgently requires and demands governmental regulations in India. Two samples of sludge were collected from Banthar Industrial Pollution Control Company (BIPCC), UP State Industrial Development Corporation (UPSIDC), Leather Technology Park, Banthar, Unnao, India. In the present study, the phytoremediation potential of Catharanthus roseus, a valued medicinal plant, with respect to chromium has been analyzed. C. roseus was shown to absorb up to about 38% of the amount of Cr present in primary and secondary sludge amended soil through roots and accumulate it to about 22% in leaves. Effect of chromium concentration on the status of antioxidant enzyme peroxidase (POD) and detoxification enzyme glutathione-S-transferase (GST) from C. roseus leaves was also observed and determined. Increased expressions of POD and GST were observed on native PAGE under stress conditions as compared to control. C. roseus can well tolerate low amounts of chromium (and accumulate it to about 22% in leaves) and can, thus, prove useful in the reclamation and remediation of chromium contaminated soil and land.
文摘<p style="margin-left:10.0pt;"> <br /> </p> <p style="margin-left:10.0pt;"> <span>The coenzyme B<sub>12</sub> dependent glutamate mutase is composed of two apoenzyme proteins subunits;S and E<sub>2</sub>, which while either fused or separate assemble with coenzyme B<sub>12</sub> to form an active holoenzyme (E<sub>2</sub>S<sub>2</sub>-B<sub>12</sub>) for catalyzing the reversible isomerization between (<i>S</i>)-glutamate and (2<i>S</i>, 3<i>S</i>)-3-methylas</span><span>- </span><span>partate. In order to assay the activity of glutamate mutase by UV spectrophotometry, this reaction is often coupled with methylaspartase which deaminates (2<i>S</i>, 3<i>S</i>)-3-methylaspartate to form mesaconate (<i>λ</i><sub>max</sub> = 240 nm, </span><span>Ɛ</span><sub><span>240</span></sub><span> = 3.8 mM<sup>-1</sup>·cm<sup>-1</sup>). The activities of different reconstitutions of glutamate mu<span>tase from separate apoenzyme components S and E in varied amount</span></span><span>s</span><span> of </span><span>coenzyme B<sub>12</sub> and adenosylpeptide B<sub>12</sub> as cofactors were measured by this assay and used to reveal the binding properties of the cofactor by the Michaelis</span><span>- </span><span>Menten Method. The values of <i>K<sub>m</sub></i> for coenzyme B<sub>12</sub> in due to reconstitutions of holoenzyme in 2, 7 and 14 S: E were determined as;1.12 ± 0.04 μM, 0.7 ± 0.05 μM and 0.52 ± 0.06 μM, respectively, so as those of adenosylpeptide B<sub>12</sub>;1.07 ± 0.04 μM and 0.35 ± 0.05 μM as obtained from respective 2 and 14 S: E compositions of holoenzyme. Analysis of these kinetics results curiously as<span>sociate</span></span><span>s</span><span> the increasing affinity of cofactors to apoenzyme with</span><span> </span><span>increased amount of component S used in reconstituting holoenzyme from separate</span><span> apoenzyme components and cofactor.</span><span> Moreover, in these studies a new method for assaying the activity of glutamate mutase was developed, whereby glutamate mutase activity is measured via depletion of NADH (<i>λ</i><sub>max</sub> = 340 nm, </span><span>Ɛ</span><sub><span>340</span></sub><span> = 6.3 mM<sup>-1</sup>·cm<sup>-1</sup>) as determined by UV spectrophotometry after addition of (2<i>S</i>,<span> 3<i>S</i>)-3-methylaspartate and pyruvate to a mixture of E<sub>2</sub>S<sub>2</sub>-B<sub>12</sub> and two auxiliary </span><span>holoenzymes system;pyridoxal-5-phosphate dependent glutamate-pyruvate </span><span>aminotransferase and N</span>ADH dependent (<i>R</i>)-2-hydroxyglutarate dehydrogenas<span>e. The activity of glutamate-pyruvate aminotransferase was relatively complete recovered upon the addition of (<i>S</i>)-glutamate and pyruvate to the mixtures of hologlutamate-pyruvate aminotransferase and (<i>R</i>)-2-hydroxylglutarate</span> dehydrogenase which were incubated with each putative inhibitor of glutamate mutase. Additionally, the new assay was used to determine the kinetic constants of (2<i>S</i>, 3<i>S</i>)-3-methylaspartate in the reaction of glutamate mutase as <i>K</i><sub>m</sub>= 7 ± 0.07 mM and <i>k</i><sub>cat</sub>= 0.54 ± 0.6 s<sup>-1</sup>. Application of Briggs-Haldane formula allowed the calculation of an equilibrium constant of the reversible isomerization, <i>K</i><sub>eq</sub> = [(<i>S</i>)-glutamate] × [(2<i>S</i>, 3<i>S</i>)-3-methylaspartate]<sup>-1</sup> = 16, where the kinetic constants of (<i>S</i>)-glutamate were determined by the standard methylaspartase coupled assay.<span></span></span> </p> <p> <br /> </p>
文摘Six hundred and fifty-eight specimens of the Clariidae were collected from seven localities in the Lake Victoria basin and the Malagarasi wetland, Tanzania. A total of three hundred unadjusted morphometric measurements and meristic counts were analysed with the aim of assessing the adequacy of morphometric technique to delineate the clariid species occurring in theLake Victoriabasin. Results showed that morphometrics augmented by multivariate analysis (PCA, DCA and cluster analysis) amalgamated the clariid fishes into three groups, the?Clarias alluaudi/C. werneri,?C. gariepinus/C. liocephalus?andClariallabes petricola. Although other workers have used this technique, the present study concluded that, standing alone morphometrics is not a substitute for external morphology in the identification of clariid fish species, as it failed to separate the clariids into their respective taxonomic species. The technique, however, insinuates the regressional morphological relationships among the clariids occurring in the Lake Victoria basin.
文摘Malaria has continued to be a health and economic problem in Africa and the world at large. Many anti-malarial drugs have been rendered ineffective due to the emergence of resistant strains of Plamodium falciparum. A key malaria parasite enzyme in glycolytic pathway, P. falciparum lactate dehydrogenase (PfLDH) is specially targeted for anti-malarial drugs development. Thus, the aim of this investigation was to determine the in silico inhibition effects of antimalarial compounds from Hoslundia opposita Vahl. namely hoslundin, hoslundal and hoslunddiol on PfLDH enzyme. The compounds were docked to the three-dimensional structure of PfLDH as enzyme using AutoDock Vina in PyRx virtual screening software. Binding affinity and position of the inhibitors were evaluated using PyMol software. The PfLDH enzyme showed two binding sites: the cofactors binding site (Site A) and secondary binding site (Site B). In the absence of the cofactor all ligands showed higher affinity than NADH, and were bound to the cofactors binding site (Site A). When docked in the presence of the cofactor, site B was the preferred binding site. Binding to cofactor site with higher binding energy than NADH suggests that these ligands could act as preferential competitive inhibitors of PfLDH. However, the binding to site B also suggests that they may be non-competitive allosteric inhibitors. Amino acid residues Gly99, Asn140, Phe100 and Thr97 were indicated to form hydrogen bonds with Hoslundin. Hoslunddiol showed hydrogen bonding with Thr97 and Met30, while Hoslundal formed hydrogen bond with Thr101 and Asn140.
文摘Fundamental units of measurements are kilograms, meters, and seconds—in regards to mass length, and time. All other measurements in mechanical quantities including kinetic quantities and dynamic quantities are called derived units. These derived units can be expressed in terms of fundamental units, such as acceleration, area, energy, force, power, velocity and volume. Derived quantities will be referred to as time, length, and mass. In order to explain that fundamental units are not equivalent with fundamental quantities, we need to understand the contraction of time and length in Special Relativity. If we choose the velocity of light as fundamental quantity and length and time as derived quantities, then we are able to construct three-dimensional space-time frames. Three-dimensional space-time frames representing time with polar coordination, time contraction and length contraction can be shown graphically.
文摘The Current Standard Model of the Universe asserts that the universe is generated from a single Big Bang event followed by inflation. There is no center to this universe, hence, no preferential reference frame to describe the motions of celestial objects. We propose a new, Shell Model of the Universe, which contends that the universe is created from multiple, concentric big bangs. Accordingly, that origin presents itself as a unique, preferential reference frame, which furnishes the simplest description of the motions of galaxies in the cosmos. This is similar in manner to how planetary motion is more straightforwardly described via a sun-centered Solar System rather than an earth-centered one. The appeal of the Shell Model of the Universe lies in its simplistic ability to resolve the paradox of quasars, explain the variability in Hubble’s Constant, and solve the problematic accelerated expansion of the universe.
文摘Meighan Wetland and its surroundings have undergone many changes in recent years.This study aims to monitor and predict land use changes using the land change model (LCM) module in the Meighan wetland.Land Sat images of years 2000,2007 and 2015 were used to produce digital land use maps.The images were classified into seven classes including;Salt lake,Agriculture,Rangeland,Manmade,Wastewater,Wetland and Mine areas.The LCM module in Idrisi GIS software was used to analyze the land use changes for predicting the land uses status in 2015,based on artificial neural network (ANN) and Markov Chain analysis.The ANN was trained with various influencing factors including;distance from road,distance from manmade areas,distance from land changed edge,distance from stream,elevation and slope.The results indicated that 1663.88 ha of the rangeland cover and 715.68 ha of the salt lake cover have been degraded during the 2000-2015 period.Furthermore,the wetland,mine,wastewater and manmade degradation are increased to 724 ha,335 ha,37 ha and 270 ha in comparison to initial land conditions.Also,the result shows that rangeland and salt lake areas will decrease in the year 2030 compare to 2015,while,wetland,mine and manmade land changes may increase.