Physical and chemical effects of phosphorus-containing compounds on laminar premixed flame

Phosphorus-containing compounds are the promising halon alternatives for flame inhibitions. However, some literatures suggested that the phosphorus-related inhibitors may behave as the unfavorable ones that will increase the burning velocity under lean-burn conditions, and this indeed posed potential threats to the fire prevention and fighting. To seek deeper insights into the reaction process, a numerical investigation was actualized to study the phosphorus-related effects on methane-air flames. By replacing a phosphorus-related inhibitor with the corresponding decomposed molecules, the detailed promoting and inhibiting effects of combustion were separated from the general chemical effect. A comparative study was carried out to identify the interaction between the two effects under different combustion conditions. It is observed that the promoting effect becomes the dominant factor during the reaction process when the equivalence ratio is smaller than 0.60. In this lean-burn condition, the exothermic reactions were faster than the others within the reaction chains due to the reduction of radical recombination in hydrocarbon oxidation. The results are believed to be useful for the further application and improvement of flame inhibitors.

Technology Development and Production of Certain Chemical Platinum Metals Compounds at JSC ＂Krastsvetmet＂

In recent years JSC "Krastsvetmet" has successfully developed the production of chemically pure compounds of precious metals.Currently methods have been developed and facilities have been provided for industrial production of the following platinum metals compounds:Rhodium(Ⅲ) chloride hydrate,rhodium(Ⅲ) chloride solution,rhodium(Ⅲ) nitrate solution,rhodium(Ⅲ) iodide,rhodium(Ⅲ) sulfate,hydrated rhodium(Ⅲ) oxide,ammonium hexachlororodiate,rhodium(Ⅲ) phosphate solution,rhodium electrolytes;Iridium(Ⅳ) chloride hydrate,iridium(Ⅲ) chloride hydrate,ammonium hexachloroiridate(Ⅳ),hexa chloriridium acid solution,hexachloriridium crystalline acid;Ruthenium(Ⅲ) chloride hydrate,ruthenium(Ⅳ) hydroxide chloride,ruthenium(Ⅳ) hydroxide chloride solution,ammonium hexachlororuthenate,ruthenium(Ⅲ) chloride solution,potassium,diaquaoctachloronitrido diruthenate.The quality of the production meets the requirements of Russian and foreign consumers.

Characteristics of physico-chemical properties, volatile compounds and free fatty acid profiles of commercial set-type Turkish yoghurts

Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.

Characteristics and chemical reactivity of biogenic volatile organic compounds from dominant forest species in the Jing-Jin-Ji area,China

Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-Ji area of China.Based on the field survey,forest resources data and the measured standard emission factors,the Guenther model developed in 1993(G93)was applied in this paper to estimate the emission of BVOCs from several dominant forest species(Platycladus orientalis,Quercus variabilis,Betula platyphylla,Populus tomentosa,Pinus tabuliformis,Robinia pseudoacacia,Ulmus pumila,Salix babylonica and Larix gmelinii)in the Jing-Jin-Ji area in 2017.Then the spatiotemporal emission characteristics and atmospheric chemical reactivity of these species were extensively evaluated.Results:The results showed that the total annual BVOCs emission was estimated to be 70.8 Gg C·year^(−1),consisting 40.5%(28.7 Gg C·year^(−1))of isoprene,36.0%(25.5 Gg C·year^(−1))of monoterpenes and 23.4%(16.6 Gg C·year^(−1))of other VOCs.The emissions from Platycladus orientalis,Quercus variabilis,Populus tomentosa and Pinus tabulaeformis contributed 56.1%,41.2%,36.0% and 31.1%,respectively.The total BVOCs emission from the Jing-Jin-Ji area accounted for 61.9% and 1.8%in summer and winter,respectively.Up to 28.8% of emission was detected from Chengde followed by Beijing with 24.9%,that mainly distributed in the Taihang Mountains and the Yanshan Mountains.Additionally,the Robinia pseudoacacia,Populus tomentosa,Quercus variabilis,and Pinus tabulaeformis contributed mainly to BVOCs reaction activity.Conclusions:The BVOCs emission peaked in summer(June,July,and August)and bottomed out in winter(December,January,and February).Chengde contributed the most,followed by Beijing.Platycladus orientalis,Quercus variabilis,Populus tomentosa,Pinus tabulaeformis and Robinia pseudoacacia represent the primary contributors to BVOCs emission and atmospheric reactivity,hence the planting of these species should be reduced.

Evaluation of Pesticide Toxicity and Chemical Compounds Revealed in Soils of Sikasso and Segou (Mali)

The contaminants of the ground are potentially harmful agents and when they are released in this medium, their persistence becomes an important concern. Because of the expressed interest, a certain number of pesticides and important chemicals and their toxicity are described in this article. The studies went on the determination of the concentration, the lethal amount of the organochlorinated compounds, chemical organophosphates, carbamates and compounds. One summer recorded 3 pesticides in 5 samples of the grounds of Sikasso and Segou (Mali). Their concentration varies from 20 (atrazine) with 45 g/kg of ground. The lethal amounts of the revealed poisons variable from 338 for phtalates to 28.710 mg/kg for hexane (alkane) thus evaluate their impact on the food chain. Organophosphates and the carbamates (insecticidal) involve a reduction of 34.2% of the number of Cyprinus carpio of fresh water. The atrazine contaminates drinking water, but the diuron modifies the behavior and the reproduction of fish by deteriorating their system of olfactive perception of natural substances. Important mortalities of birds are noted around the corn fields of Bougouni treated by the carbofuran. The pesticides involve at the man a reduction in fruitfulness, an increase in the risk of miscarriage of premature birth, congenital malformations and cancers.

Changes in Chemical Composition of Soluble Organic Chemical Compounds during Litters Decomposition into Tropical Forest of Milletia laurentii De Wild

Recent publication attested that in the urban forest of Brazzaville, litter decomposition is faster with almost 45% of initial weight loss than in the dry season, where an average loss of 26% in initial litter weight is noted (Ifo et al., 2018). This study was carried out in the urban forest of Brazzaville to follow the decomposition of some organic compounds/secondary metabolites (reducing Sugars, total Flavonoid and Polyphenols) of the leaves litters of two tropical species Antiaris toxicaria Lesch and Millettia laurentii De Wild. Thin-layer chromatography and spectrophotometric assay of these metabolites were used on the samples of litters collected in the field on various dates of follow-up of the decomposition (0 d, 14 d, 28 d, 42 d, 56 d, 72 d and 84 d). The chromatographic profile of initial litters shows a series of spots on yellow florescence materializing presence of flavonoids, green fluorescence revealing the presence of the acids phenols derived from the cinnamic acid. But the chromatographic profile of the two litters in decomposition after two weeks remains without structural information, being able to characterize the decomposition of the chemical families highlighted in the initial litters. Also, the analysis of quantitative total reducing sugar in the initial litters, gives average concentrations of 64.4, 58.6, 57.5 g EG/kg Ms respectively for the litters of Millettia laurentii De Wild, Antiaris toxicaria Lesch and the mixed litters (Millettia laurentii and Antiaris toxicaria). Comparatively with the other types of litters, the initial average concentrations in phenolic compounds (polyphenols and flavonoids totals) were the highest for the litters of Antiaris toxicaria Lesch (27.3 g EAG/kg Ms and 13.07 g EC/kg Ms) (P = 0.001). The losses of organic chemical compounds are more significant during the first two weeks of experiment than after this period. Antiaris toxicaria Lesch loses on average 43.8 g EG/kg Ms of reducing Sugars, 12.21 g EC/kg Ms of totals flavonoids and 26.4 g EAG/kg Ms of total polyphenols, equivalent to 30% of loss of the initial weight. Average losses of 45.7 g EG/kg Ms were obtained for reducing sugars, 1.5 g EC/kg Ms for totals flavonoids and 8.72 g EAG/kg Ms for totally phenols in for the litters of Millettia laurentii, comparable to 24% in initial weight loss. This study showed on the one hand, the direct link between rainfall and litters decomposition and the losses in weight of the litters resulted in dissolution in the water of the studied compounds.

The alkynyl-containing compounds from mushrooms and their biological activities

Mushrooms have been utilized by humans for thousands of years due to their medicinal and nutritional properties.They are a crucial natural source of bioactive secondary metabolites,and recent advancements have led to the isolation of several alkynyl-containing compounds with potential medicinal uses.Despite their relatively low abundance,naturally occurring alkynyl compounds have attracted considerable attention due to their high reactivity.Bioactivity studies have shown that alkynyl compounds exhibit significant biological and pharmacological activities,including antitumor,antibacterial,antifungal,insecticidal,phototoxic,HIV-inhibitory,and immunosuppressive properties.This review systematically compiles 213 alkynyl-containing bioactive compounds isolated from mushrooms since 1947 and summarizes their diverse biological activities,focusing mainly on cytotoxicity and anticancer effects.This review serves as a detailed and comprehensive reference for the chemical structures and bioactivity of alkynyl-containing secondary metabolites from mushrooms.Moreover,it provides theoretical support for the development of chemical constituents containing alkynyl compounds in mushrooms based on academic research and theory.

Research on Ce-Zr compounds on modifying γ-alumina washcoat on FeCrAl foils

Ce-Zr compounds such as Cc0.68Zr0.3202 solid solution, Ce/Zr nitrate and CeO2/ZrO2 were added into γ-alumina-based slurries, which were then loaded on FeCrAl foils pretreated at 950℃ and 1100℃. The microstructures and adhesion performance between the substrates and the washcoats were measured by SEM, BET surface area, ultrasonic vibration and thermal shock test. The results show that the addition of Ce0.68Zr0.32O2 solid solution, Ce/Zr nitrate and CeO2/ZrO2 into the slurries can improve γ-Al2O3-based washcoat adhesion on FeCrAl foils. Furthermore, ceria-zirconia solid solution increases the adhesion of the washcoat on the surface of an FeCrAl foil than the two others. The specific surface area of this washcoat remains about 4345 m^2/g and the weight loss is below 4.0% even after aging test of 10% steam-containing air at 1050℃ for 20 h.

Chemical Defense of Soft Coral Sinularia polydactyla from the Red Sea Against Marine Biofilm-Forming Bacteria

Soft corals are an important group of organisms that live in reef ecosystems. In this study, the chemical defense of soft coral Sinularia polydactyla against biofilm-forming bacteria was assessed. The soft coral S. polydactyla was collected from the Obhur creek of the Red Sea and the bioactive compounds were extracted under different conditions using methanol and hexane as solvents. Results revealed that the bioactive compounds produced by the soft coral S. polydactyla were active against the growth, hydrophobicity and extracellular polymeric substances production of the biofilm-forming bacteria. However, the damage or injury in soft coral tissue caused a decrease in the activity against biofilm-forming bacteria. GC-MS analysis revealed that sesquiterpenes were abundant in normal coral sample extract while cembranoids were abundant in damaged coral sample extracts. In general, the results indicated that the soft corals either under stress or with damage may not have a strong chemical defense against the colonizing marine organisms and competitors.

The use of yellow phosphorus to destroy toxic organic compounds

A new method for generating reactive species to destroy toxic organic chemicals has been developed. This method reacts yellow phosphorus with O_2, in moist air to produce species such as O,O_3, PO, and PO_2, which are capable of reacting with various types of organics. Toxic organic com-pounds are converted to small molecular wight organic acids, aldehydes, and/or alcohols, while yel-low phosphonis is oxidital into phosphoric acid, which may be recovered as a valuable byproduct.This technique has ben demonstrated to be effective for destroying many types of toxic organiccompounds. including PAH, aromatic chlorides, amines, alcohols, and acids, nitro-aromatics,heterocyclic hydrocarbons, PCB, aliphatic chlorides and sulfides, dyes, and pesticides.

Accumulation and geochemical evidence for the Little Ice Age episode in eastern Antarctica

Data on accumulation and concentration of chemical compounds recorded in an essentially unexplored area(Dome Argus)of the Indian Ocean sector of eastern Antarctica during the past 2,680 years(680 B.C. to 1999 A.D.) are presented. During the first 1, 700 years(680 B. C. to 1000 A. D.), the accumulation data shows a slightly decreasing trend, while chemical ions appear to be stable, representing a stable climatic condition. An intensive increasing trend of the accumulation occurred during the 12^(th) to 14^(th) century. The period from 15^(th) to 19^(th) century was characterized by a rapid reducing accumulation and concentrations of volatile compounds suffering post-depositional loss linked to sparse precipitation amount,which was temporally consistent with the Little Ice Age(LIA) episode. Comparison between observed accumulation rates with other eastern Antarctic ice cores show a consistent decreasing trend during LIA, while sea salt and dust-originated ions increased due to sea ice extent and intensified atmospheric transportation. Distribution of volcanic originated sulfate over the Antarctic continent show a significant change during the 15^(th) century, coincident with the onset of the LIA. These results are important for the assessment of Antarctic continent mass balance and associated interpretation of the Dome A deep ice core records.

Evaluating Groundwater Pollution Using Hydrochemical Data: Case Study (Al Wahat Area East of Libya)

Water is one of the most challenging current and future natural resources, which will directly affect the environment and development by the changes in its quantity, quality and regional distribution. However, Water quality is the critical factor that influences human health and irrigation proposer. This work aims to investigate hydrochemical analysis and geochemical processes influencing the groundwater of Al Wahat area (Jalou, Awjla and Jukherra), which is located in central east Libya. Thirty four water samples collected from domestic and agricultural water wells were analyzed and used for conventional classification techniques which were Piper, Durov and Stiff diagrams to evaluate geochemical processes. Cluster analysis was used to identify the water type and ions concentration and distribution. Results show significant increase of dissolved salts, especially Nitrates. Elevated nitrates concentration can be attributed to either the disposal of untreated sewage water from disposal ponds and septic tanks or the infiltration of irrigation water saturated with fertilizing chemicals. Therefore, irrigation wells revealed that suffering from nitrate contamination caused an increase of the chance of nitrate pollution. In addition, contour maps present a sudden increase in the total dissolved salts (TDS) in the northeastern part?coincident with the highest of secondary ions of NO3 content, indicating the infiltration of irrigation water which is responsible partially for the groundwater degradation. Hydrogeochemical facie is NaCl type and enrichment of Na+ and Cl- can be attributed to urban untreated wastewaters and high rate of evapotranspiration. The concentrations of heavy elements such as Zn, Pb, Cu, Cd, Ni and Cr were low and within the WHO ranges.

A systematic study on mycochemical profiles, antioxidant, and anti-inflammatory activities of 30 varieties of Jew’s ear(Auricularia auricula-judae)

The health-promoting properties and chemical profiles of 30 Jew’s ear mushroom varieties were investigated. The antioxidant properties were determined by ferric reducing antioxidant power(FRAP), 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging, 2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) free radical scavenging, and metal chelating ability(MCA) assays, while phenolic profiles were determined by total phenol content(TPC) and total flavonoid content(TFC) colorimetric assays. Total carbohydrate, β-glucan, and melanin contents were determined by colorimetric methods. 5’-Nucleotides, vitamin D_(2), ergosterol, and ergothioneine contents were determined by high performance liquid chromatography(HPLC). Anti-inflammation activities of Jew’s ear were evaluated by the colorimetric protease inhibitory method. The results showed that Jew’s ear mushrooms possessed substantial phenolics and antioxidant properties. All the Jew’s ear varieties contain high amount of total carbohydrate, β-glucan, reducing sugar, melanin, pectin, vitamin D2, ergosterol, and ergothioneine. The current findings could provide scientific information for breeders to nurture desired varieties and for food industry to develop new health promoting products.

Research Progress on the Monitoring of Precursor of Atmospheric Ozone——Volatile Organic Compounds

Volatile organic compounds(VOCs)are important precursors of ozone and PM_(2.5).At present,VOCs have gradually become the focus of air pollution control after fine particles in China,and a series of documents,standards and planning on VOCs were issued from the state to each area.The analysis on source apportionment and control of VOCs have also become a hot spot in atmospheric environmental protection research of China at present stage.The research work on VOCs in ambient air is the basis and premise of scientific and effective prevention and control of VOCs pollution.In this paper,research progress on the monitoring of VOCs is introduced systemically,and main monitoring and evaluation methods of atmospheric VOCs are explored from monitoring analysis method,chemical reaction activity and health risk assessment.Moreover,concentration characteristics and source apportionment of VOCs in the regions at home and abroad that have carried out VOCs research work are compared and summarized.The research could provide reference for source apportionment of VOCs in other cities of China.

A study on the interactions among several plant secondary compounds and aphids

The research, focused on the specific interactions among seven plant secondary compounds and aphids, was carried out and the preliminary results showed: (1) 'T-typed tube method' was regarded as the best method compared with others designed to observe the interactions. (2) Cabbage aphid was able to be attracted by laurolene while it was not susceptible to α-pinene, β-pinene and diamylene. (3) Gossypol, a major secondary substance in cotton, was able to be implicated as feeding attractant to cotton aphid. (4) Rutin might be implicated repellent to cotton aphid.

Chemical Thermodynamic Analysis of Silicon Doping in MOCVD of GaAs System

With chemical thermodynamic method, enthalpies, entropies and heat capacities of (SiH3)nAsH3-n (1&len&le3), (CH3)4-mSiH4-m (1&lem&le4) and their radicals were calculated. Homogeneous reaction equilibrium of 65 gas phase species in SiH4 (or Si2H6) doped MOCVD GaAs by TMG and AsH3 system was analyzed, the relations of gas phase partial pressures with growth temperatures and input partial pressures were calculated. When the gas phase is saturated with a GaAs: Si solid, the gas phase partial pressures and solid phase silicon impurity (SiGa-As, Ga-SiAs, SiGa-SiAs) concentrations were calculated under different growth temperatures and input partial pressures. With the above results, some of the Si doping behavior in MOCVD of GaAs were explained.

Study of Properties of Intermetallic Compounds of Rare Earth Metals by Artificial Neural Networks

The results of an expert system of lanthanide intermetallic compounds using artificial neural networks and chemical bond parameter method were reported. Two pattern recognition neural models, one for prediction of the occurrence of 1 : 1 lanthanide intermetallic compounds with CsClstructure and the other for prediction of congruent or incongruent melting types, were developed. Four regression neural models were also developed for prediction of melting point of these compounds. In order to get rid of overfitting, cross-vahdation method was used for the neural models. And satisfactory results were obtained in all of the neural models in this paper.

High Quality Zinc Sulfide Epitaxial Layers Grown by Metalorganic Chemical Vapour Deposition

ZnS films were successfully grown by metallorganic chemical vapour deposition (MOCVD) at atmospheric pressure on (100) GaAs substrates. The deposition was carried out at a substrate temperature between 280 approximately 550°C with optimisation of reactor design and growth conditions. The gas phase prereaction is effectively restrained. These epilayers exhibit high crystallographic quality and reveal a mirror surface morphology. The peak halfwidths of X-ray diffraction patterns from their (400) faces are within 0.06 approximately 0.09°. The epilayers grown on (111) GaAs, (112¯0) Al2O3 and (100) Si have proven to be single crystalline feature. The optical and electrical characteristics of ZnS epilayers are measured by photoluminescence, cathodeluminescence, and the Van der Pauw method. The results indicate that there are not a large number of deep centers that could be detected both at 77K and at room temperature. A broad CL peak around 2.897eV and 2.672eV was observed only under very strong excitation. Their origin has not been examined. All epilayers present high resistivities up to 1013Ω&middotcm.

Growth and characterization of InAsSb alloys by metalorganic chemical vapour deposition

Low pressure metalorganic chemical vapour deposition （LP-MOCVD） growth and characteristics of InAsSb on （100） GaSb substrates are investigated. Mirror-like surfaces with a minimum lattice mismatch are obtained. The samples are studied by photoluminescence spectra, and the output is 3.17μm in wavelength. The surface of InAsSb epilayer shows that its morphological feature is dependent on buffer layer. With an InAs buffer layer used, the best surface is obtained. The InAsSb film shows to be of n-type conduction with an electron concentration of 8.52 × 10^16 cm^-3.