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Hyper Gravity-Induced Transients in <i>Phycomyces</i>as Measured by Single Beam Spectrophotometer on the Sounding Rocket TEXUS 50
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作者 Werner Schmidt 《Journal of Modern Physics》 2018年第2期273-286,共14页
In the first paper of two referring to the TEXUS 50 campaign using micro dual wavelength spectrometers (MDWS) we kinetically determined the threshold1 for GIACs (gravity-induced absorption changes) in Phycomyces to be... In the first paper of two referring to the TEXUS 50 campaign using micro dual wavelength spectrometers (MDWS) we kinetically determined the threshold1 for GIACs (gravity-induced absorption changes) in Phycomyces to be lower than 25 × 10&minus;3 g (http://file.scirp.org/pdf/JMP_2015082810060783.pdf). In this second paper, we attended measurement of GIAC-spectra. Unexpectedly, during the upwards movement, i.e. the hypergravity phase up to top acceleration values reaching 11.6 g at 35.4 s after liftoff we observed transient GIAC-spectra ranging from 380 to 750 nm. In addition, during the whole acceleration phase of 68.2 s, another component near 700 nm develops which remains stable during the whole “free fall trajectory parabola” for 381.3 s. The subsequent reentry of the rocket leads to extraordinary deceleration values up 37.8 g, completely destroying Phycomyces sporangiophores excluding their spectral measurement. During the microgravity phase and by centrifuge operation we were unable to detect any GIAC-spectra (in contrast to kinetic MDWS-measurements, first paper). 展开更多
关键词 MDWS (Micro-Dual Wavelength spectrophotometer) Single Beam spectrophotometer (SBS) Diode Array Spectrometer (USB-2000+ Ocean Optics) GIAC (Gravity-Induced Absorption Change) PHYCOMYCES blakesleeanus Sporangiophore Micro- and Hypergravity Texus 50 Sounding Rocket Graviperception. HYPER Gravity-Induced Transients
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Assessment of Long Term UV Radiation Measured by the Brewer Spectrophotometer in Hong Kong during 1995-2005 被引量:2
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作者 T.J. Wang K.S. Lam +1 位作者 Q. Liu X.M. Wang 《Atmospheric and Climate Sciences》 2011年第1期9-17,共9页
Time series of daily UV radiation measured by the ground-based Brewer spectrophotometer #115 in Hong Kong during 1995-2005 were studied through statistics analysis, with focus on the variability and long term changes ... Time series of daily UV radiation measured by the ground-based Brewer spectrophotometer #115 in Hong Kong during 1995-2005 were studied through statistics analysis, with focus on the variability and long term changes in relation to total ozone, clouds and AOD (Aerosol Optical Depth). The 11-year mean UV daily dose is 2644±262 J/m2, with maxima(3311 J/m2) in 2000 and minima (2415 J/m2) in 2002. The data were compared with that from TOMS (Total Ozone Mapping Spectrometer) Version 8 and show general agreement between the two. However, the Brewer UV measurement is about 10% lower compared to TOMS data. Apart from the common-known strong seasonal cycle, 26 month periodical was resolved by use of wavelet analysis, which was believed to be associated with quasi-biennial oscillation (QBO) of general circulation. In cloudy days, the annual mean UV daily dose decrease 3.5% to 44.5% compared to clear days. It was also found that surface UV irradiance has close relation to air pollution. Under clear sky condition, 1% AOD increase will lead to 0.2% UV decrease. While global UV radiation increase due to the worldwide observed ozone depletion, investigations indicate that this trend is not significant in Hong Kong during the last 11 years. The possible causes can be attributed to the compensative effect from two aspects. One is the increase of UV resulting from the reduction of clouds with rate of 0.56/10 yr. The other is the decrease of UV due to the enhancement of total ozone and AOD with a rate of 4.23 DU/10 yr and 0.33/10 yr, respectively. 展开更多
关键词 UV RADIATION Brewer spectrophotometer TOMS Hong Kong
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A Novel Chip-based Spectrophotometer for Online Detection
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作者 Haoyuan Cai Min-Hsien Wu Zheng Cui 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2006年第A03期346-348,共3页
A chip-based spectrophotometer integrated with optical fiber is successfully demonstrated.Grade concentration of lactate solution flowed through the chip to perform an online detection.The response time (100s)and Limi... A chip-based spectrophotometer integrated with optical fiber is successfully demonstrated.Grade concentration of lactate solution flowed through the chip to perform an online detection.The response time (100s)and Limit of Detection (LOD, 50mg/L)of the device were measured.This device shows comparable performance with traditional commercial instrument, while greatly decreases the sample requirement per detection and reduces the size of total system,introducing a novel method for real-time detection. 展开更多
关键词 spectrophotometer optical fiber online detection
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Spectrophotometer standardization in UV-Vis spectral region
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作者 Alaa-Eldin A Abd-Elmageed Essam M Elmoghazy Fatma Elsharkawy 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2016年第1期40-43,共4页
Ultraviolet-visible(UV-Vis)spectrophotometry is commonly used in analytical laboratories for qualitative and quantitative analyses.To make the data obtained reliable,an experimental instrument must be calibrated.Nat... Ultraviolet-visible(UV-Vis)spectrophotometry is commonly used in analytical laboratories for qualitative and quantitative analyses.To make the data obtained reliable,an experimental instrument must be calibrated.National Institute for Standards(NIS)in Egypt builds up aphotometric method to ensure the competence of absorbance and transmittance to the standard international and national requirements.This paper presents an instrument for UV-Vis measurement,discusses the factors affecting measurement reliability and estabishes the uncertainty model including correspoding measurement parameters. 展开更多
关键词 spectrophotometer STANDARDIZATION ABSORBANCE UNCERTAINTY
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Determination of Thioglucoside in Cabbage by Using the Ultraviolet-visible Light Spectrophotometer
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作者 WANGJing WANGQing 《Journal of Northeast Agricultural University(English Edition)》 CAS 2000年第2期149-157,共9页
The ultraviolet-visible light spectrophotometer method was adopted to determine thioglucoside in cabbage with the seeds.Individual plant of cabbage was used as test materials,palladium chloride as complexing agent and... The ultraviolet-visible light spectrophotometer method was adopted to determine thioglucoside in cabbage with the seeds.Individual plant of cabbage was used as test materials,palladium chloride as complexing agent and sodium cellulose glycolate as dispersing agent.The results showed that palladiumd thioglucoside method could be taken as a quick,easy and precise quantitative analysis method to determine thioglucoside in cabbage. 展开更多
关键词 Ultraviolet visible light spectrophotometer method CABBAGE thioglucoside determination method
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Transmittance Spectrum of Unbranded Sunglasses Using Spectrophotometer
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作者 Huseyin Gursoy Hikmet Basmak +1 位作者 Hamza Esen Ferhan Esen 《Open Journal of Ophthalmology》 2015年第1期1-5,共5页
Background: The sunglass standards are not strictly implemented in many countries except Aus-tralia. The purpose of the study was to evaluate the optical properties of unbranded sunglasses for light transmittance. Met... Background: The sunglass standards are not strictly implemented in many countries except Aus-tralia. The purpose of the study was to evaluate the optical properties of unbranded sunglasses for light transmittance. Methods: Unbranded sunglasses with no information about their specifications were included. They were allocated to two groups based on their prices;the ones > 25 US$ (Group A) and the cheaper ones (Group B). Their transmittance spectrum was measured between 190 nm and 900 nm using a double beam scanning spectrophotometer. The European standard for sunglasses was used to evaluate their compliance regarding ultraviolet radiation (UVR) transmittance and minimum requirement for wearing when driving. Results: Thirty-eight sunglasses (Group A = 20 and Group B = 18) were evaluated. Four sunglasses in each group were non-compliant. Percentage transmittance of visible light was <8% in five sunglasses of Group A and in three of Group B, so these were not appropriate to wear when driving. Totally six sunglasses of Group A and five of Group B were non-compliant and/or inappropriate to wear when driving. Conclusions: Based on our findings about their UVR protection and visible light transmittance %, eye care professionals must warn people against the use of unbranded sunglasses without any information about their specifications. 展开更多
关键词 Sunglass spectrophotometer TRANSMITTANCE SPECTRUM ULTRAVIOLET Radiation VISIBLE Light
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Determination of Palladium II in 5% Pd/BaSO<sub>4</sub>by ICP-MS with Microwave Digestion, and UV-VIS Spectrophotometer
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作者 Y. Yildiz M. Kotb +3 位作者 A. Hussein M. Sayedahmed M. Rachid M. Cheema 《American Journal of Analytical Chemistry》 2019年第4期127-136,共10页
Determination palladiums have been reported 5% (w/w) Pd/BaSO4 known as Rosenmund Catalyst. The determination of palladium II known as Rosenmund Catalyst is always an expensive procedure usually involving procedures su... Determination palladiums have been reported 5% (w/w) Pd/BaSO4 known as Rosenmund Catalyst. The determination of palladium II known as Rosenmund Catalyst is always an expensive procedure usually involving procedures such as flame atomic absorption spectrophotometry, emission spectrometry, and many spectrophotometric methods. In this study, palladium II in 5% Pd/BaSO4, was synthesized and employed to develop an extractive UV-Visible Spectrophotometric, and an inductively coupled plasma mass spectrometry ICP/MS methods for the determination of palladium II. Specification for Pd is 4.85% to 5.10%;the result was 4.97% for the UV-Visible spectrophotometer and 4.90% for the ICP/MS. Both results meet the requirements. 展开更多
关键词 PALLADIUM DETERMINATION 5% PALLADIUM Barium Sulfate Inductively Coupled Plasma Mass Spectrometry UV-VISIBLE spectrophotometer Microwave Digestion
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The Effectiveness of a Portable Fluorescence Spectrophotometer for Early Detection of Oral Cancer
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作者 Katsuhiro Asaka Akira Fukatsu Chiaki Komine 《Open Journal of Stomatology》 2022年第1期30-31,共12页
<strong>Purpose:</strong> To investigate whether photodynamic diagnosis (PDD) using a portable fluorescence spectrophotometer (FC-1) can easily and objectively discriminate between normal and tumor cells a... <strong>Purpose:</strong> To investigate whether photodynamic diagnosis (PDD) using a portable fluorescence spectrophotometer (FC-1) can easily and objectively discriminate between normal and tumor cells at the dental chairside, and to further compare it with PDD that requires speculum examination by focusing on protoporphyrin IX (PPIX). <strong>Methods: </strong>Three cell lines (2 human oral squamous cell carcinoma-derived cell lines, HSC-2 and HSC-3 cells, and oral keratinocytes, HOK cells) were cultured. 5-Aminolevulinic acid hydrochloride (5-ALA) and deferoxamine mesylate (DFO) were mixed in DMEM, and the mixture was set to Control (DMEM only) and PDD (5-ALA+DFO) groups. And then, a fluorescence was measured under room temperature (RT) and 37&deg;C (Incubation) by using FC-1. In this study, the two conditions were combined with the Control and PDD groups to form the Control/RT, Control/Incubate, PDD/RT, and PDD/Incubate groups. Additionally, the amount of singlet oxygen (1O2) generated by irradiation with 405 nm LED was measured using electron spin resonance spectroscopy to detect PPIX in the cell supernatant after 24 hours. <strong>Results:</strong> In HSC-2 and HSC-3, the fluorescence intensity values increased significantly at 2 hours between the Control/RT and PDD/RT groups. In addition, there was a significant difference between HSC-2 and HSC-3 compared to HOK. In all cell lines, the fluorescence intensity values of the PDD/Incubate group were significantly higher than those of the PDD/Control group. The amount of <sup>1</sup>O<sub>2</sub> generated by 405 nm LED irradiation was higher in the cell supernatants of all cell lines in the order of Control/RT < Control/Incubate < PDD/RT < PDD/Incubate group, and HSC-3 in the PDD/Incubate group showed a significant increase compared to HOK. <strong>Conclusion: </strong>It is suggested that PDD using FC-1 can clearly distinguish between normal cells and tumor cells in vitro studies using cell lines at 2 hours under 37&deg;C, and it can detect not only intracellular PPIX, but also extracellular PPIX. 展开更多
关键词 Photodynamic Diagnosis Portable Fluorescence spectrophotometer Oral Cancer Protoporphyrin IX
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The Color of Natural Teeth Investigated by Visual Perception and Spectrophotometer
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作者 Teuta Pustina-Krasniqi Ariana Bytyci +5 位作者 Teuta Bicaj Enis Ahmedi Linda Dula Zana Lila Arlinda Dragusha Nexhmije Ajeti 《Open Journal of Stomatology》 2015年第2期26-35,共10页
The advantage of electronic devices is to eliminate the subjectivity. Based on individual capabilities, visual perception has its disadvantages. The aim of this study was to find out the possible shade difference betw... The advantage of electronic devices is to eliminate the subjectivity. Based on individual capabilities, visual perception has its disadvantages. The aim of this study was to find out the possible shade difference between the upper and lower teeth, visual perception versus spectrophotometry as well as proving that females are better in visual perception of colour matching. 82 subjects (dental students) of this study determined the color of each other’s natural teeth. The color of 1640 teeth (incisors, canines and premolars), was matched by visual perception and by Vita Easyshade spectrophotometer. The matching was focused on the middle third of buccal surfaces of the examined teeth. In this study, it was found that there was a difference of color between the teeth of the upper and lower jaw. The percentage of the accordance between two methods was 28.35% for all examined teeth. The color determination at central incisors showed the highest value of accordance 40.85%. Based on Vitapan 3D Mastershade, the most frequent color was 2M2. 展开更多
关键词 Teeth Color Visual Perception spectrophotometer Accordance
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Determination of Chlorogenic Acid,Geniposide,Total Flavonoids and Total Triterpenes in Wulan-13
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作者 Xiaohua WU Burenbatu 《Medicinal Plant》 2024年第2期6-9,共4页
[Objectives]This study was conducted to establish a method for the determination of chlorogenic acid,geniposide,total flavonoids and total triterpenes in Wulan-13.[Methods]The contents of chlorogenic acid and geniposi... [Objectives]This study was conducted to establish a method for the determination of chlorogenic acid,geniposide,total flavonoids and total triterpenes in Wulan-13.[Methods]The contents of chlorogenic acid and geniposide were determined by HPLC,and the contents of total flavonoids and total triterpenes were determined by an ultraviolet spectrophotometer.[Results]There was a good linear relation between the mass of chlorogenic acid reference substance and the peak area in the range of 0.05-0.45μg,and the regression equation was Y=2524.1X+3.1943,(r=0.9998).A good linear relationship was found between the mass of gardenoside reference substance and the peak area in the range of 0.776-6.984μg,and the regression equation was Y=1670.5X+64.804,(r=0.9998).There was also a good linear relation between the mass of rutin reference substance and its absorbance in the range of 0.00808-0.04848 mg,and the regression equation was Y=12.916X+0.014,(r=0.999).The mass of oleanolic acid reference substance had a good linear relation with its absorbance in the range of 0.00418-0.0209 mg,and the regression equation was Y=51.89X-0.0839,(r=0.9991).[Conclusions]The content determination method is simple,reliable and reproducible,and suitable for controlling the contents of chlorogenic acid,geniposide,total flavonoids and total triterpenes in Wulan-13. 展开更多
关键词 Wulan-13 HPLC Ultraviolet spectrophotometer Content determination
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Spectrophotometer with enhanced sensitivity for uric acid detection 被引量:1
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作者 Nurfatihah Che Abd Rashid Nor Hafizah Ngajikin +4 位作者 Asrul Izam Azmi Rashidah Arsat Suhaila Isaak Noran Azizan Cholan Nur Ellina Azmi 《Chinese Optics Letters》 SCIE EI CAS CSCD 2019年第8期66-70,共5页
A spectrophotometer with an LED as the light source for uric acid detection is proposed in this work. The mechanism of uric acid detection is based on energy absorbed by sodium urate, which is a chemical product of ur... A spectrophotometer with an LED as the light source for uric acid detection is proposed in this work. The mechanism of uric acid detection is based on energy absorbed by sodium urate, which is a chemical product of uric acid and sodium hydroxide solution. For the performance validation, comparison between the spectrophotometer with an LED and halogen lamp is carried out. Measurement results suggest that the spectrophotometer system with LED light has better sensitivity than that with halogen light. At a 460 nm wavelength,the sensitivity for the spectrophotometer with an LED is 0.0046 dL/mg, which is 73% higher than that with halogen light that records 0.0012 dL/mg. This enhanced sensitivity is attributed to the higher luminous efficacy of the LED light beam. As a result, a larger amount of flux interacts with the sample, leading to the sensitivity enhancement. The spectrophotometer with an LED is also applied for the detection of uric acid in a real human urine sample. Based on the experimental data at a 460 nm wavelength, the method manages to achieve the sensitivity of 0.0016 dL/mg, accuracy of 96.01%, limit of detection of 4.79 mg/dL, and limit of quantification of 14.52 mg/dL. These findings show that the use of LED as the input light source is promising for the spectrophotometer. 展开更多
关键词 spectrophotometer MECHANISM SHOW
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REMOTE SENSING OF ATMOSPHERIC CONSTITUENTS AND THE MULTI-FUNCTION SPECTROPHOTOMETER
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作者 薛庆渝 钮建国 +1 位作者 赵学鹏 郭松 《Acta meteorologica Sinica》 SCIE 1991年第3期352-359,共8页
A multi-functional solar and skylight spectrophotometer has been developed for the study of atmospheric constituents and aerosols. The instrument and its performance are described. Due to telescope structure and lock-... A multi-functional solar and skylight spectrophotometer has been developed for the study of atmospheric constituents and aerosols. The instrument and its performance are described. Due to telescope structure and lock-in amplification technique adopted,the sensitivity of the instrument is high enough to conduct direct sun moon and twilight measurement for several atmospheric species and the degree of polarization and intensity observation for sky light. From measured results, the total column abundance of atmospheric species and the optical characteristics of aerosol can be retrieved. In this paper, the daily averaged column abundance of O_3 measured in Beijing by direct sun was compared with Dobson spectrophotometer nearby. The two did not show significant difference. 展开更多
关键词 remote sensing trace gases multi-function spectrophotometer band absorption method
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Application of an optical nitrate profiler to high-and low-turbidity coastal shelf waters
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作者 Yanpei Zhuang Yangjie Li +5 位作者 Xizhen Liu Shichao Tian Bin Wang Zhongqiang Ji Haiyan Jin Jianfang Chen 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第1期103-108,共6页
Here,we report the results of high-resolution nitrate measurements using an optical nitrate profiler(in situ ultraviolet spectrophotometer,ISUS)along transect across a high-turbidity shelf(East China Sea)and a low-tur... Here,we report the results of high-resolution nitrate measurements using an optical nitrate profiler(in situ ultraviolet spectrophotometer,ISUS)along transect across a high-turbidity shelf(East China Sea)and a low-turbidity shelf(Chukchi Sea).The ISUS-measured nitrate concentrations closely reproduced the results measured by conventional bottle methods in low-turbidity waters.However,for high-turbidity waters of the East China Sea(salinity<30),a correction factor of 1.19 was required to match the standard bottle measurements.The high-resolution ISUS data revealed subtle spatial variability(e.g.,a subsurface nitrate minimum)that may have been missed if based solely on bottle results.Four main structures of the nitracline on the East China Sea are apparent from the ISUS nitrate profile.High-resolution nitrate data are important for studying nitrate budgets and nutrient dynamics on continental shelves. 展开更多
关键词 high-resolution nitrate measurements in situ ultraviolet spectrophotometer(ISUS) nutrient dynamics nitracline East China Sea Chukchi Sea
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Studies on Heavy Metals Levels in Hepatic Tissues of Cat Fishes(Clarias gariepinus)from River Ibi,Donga and Gindin-Dorowa in Taraba State Nigeria,in Relation to key Enzyme of heme Biosynthetic Pathway
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作者 Ebenezer Morayo Ale Steve Osagie Asuelimen 《Toxicology Advances》 2023年第4期8-14,共7页
Fishes are excellent markers of the extent of pollution from heavy metals in aquatic environments given that they are found at various levels of the food chain.This study aimed to investigate the bioaccumulation of he... Fishes are excellent markers of the extent of pollution from heavy metals in aquatic environments given that they are found at various levels of the food chain.This study aimed to investigate the bioaccumulation of heavy metals(Zn,Pb,Cd,As,and Hg)as well as the activity of delta-aminolevulinic acid dehydratase(δ-ALA-D)in the livers of cat fishes(Clarias gariepinus)collected from three rivers(Donga,Ibi and Gindin-Dorowa)in Taraba State,Nigeria.The concentrations of heavy metals in the liver tissues were determined using an atomic absorption spectrophotometer in accordance with the method of AOAC(2019),while theδ-ALA-D activity was assayed using the method of Sassa(1982).Results revealed that only Zn and As were present in the liver samples from the three rivers.Pb was found only in the liver from Gindin-Dorowa at the concentration of 0.0012mg/kg which is not significant(P<0.05)when compared with other locations,while Hg and Cd were absent in all the liver samples.The liver sample from Gindin-Dorowa had the highest concentration of Zn(4.2500 mg/kg),followed by Ibi(3.2067 mg/kg),and Donga having the least(2.5500 mg/kg),which were all substantially(P<0.05)different from one another.However,there was no significant(P<0.05)difference in the As composition of liver from Donga(0.0013 mg/kg),Ibi(0.0012 mg/kg)and Gindin-Dorowa(0.0010 mg/kg).The result ofδ-ALA-D activity showed that the highest enzymatic activity was found in the liver sample from Donga which has the least Zn and no Pb content,followed by Ibi sample.This validates the report that heavy metals impairδ-ALA-D activity.Nonetheless,the concentrations of all metals in fish livers from all regions do not exceed the acceptable limits set by international law,making them safe for human consumption and possibly not having a negative impact on public health.Since there is little or no industrial activity in the studied locations,these levels may be consequent to low anthropogenic inputs.The current situation should be safeguarded to prevent pollution of the river’s aquatic biota in the near future,and more appropriate steps should be made to guarantee higher fish quality and life in the rivers. 展开更多
关键词 heavy metals BIOACCUMULATION delta-aminolevulinic acid dehydratase Atomic Absorption spectrophotometer Clarias gariepinus BIOACCUMULATION
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Visual modeling reveals cryptic aspect in egg mimicry of Himalayan Cuckoo(Cuculus saturatus) on its host Blyth's Leaf Warbler(Phylloscopus reguloides) 被引量:12
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作者 杨灿朝 蔡燕 梁伟 《Zoological Research》 CAS CSCD 北大核心 2011年第4期451-455,共5页
Brood parasitism and egg mimicry of Himalayan Cuckoo(Cuculus saturatus) on its host Blyth's Leaf Warbler(Phylloscopus reguloides) were studied in south-western China from April to July 2009.The cuckoo laid a whit... Brood parasitism and egg mimicry of Himalayan Cuckoo(Cuculus saturatus) on its host Blyth's Leaf Warbler(Phylloscopus reguloides) were studied in south-western China from April to July 2009.The cuckoo laid a white egg with fine brown markings on the blunt end.The eggs were conspicuously bigger than the host's own,with 2.06 g in mass and 1.91 cm3 in volume.Visual modeling showed that the cuckoo eggs,which from the human eye appeared to mimic the host eggs to a great extent,were completely different from the host eggs in both hue and chroma.The characters of the Himalayan Cuckoo nestling,reported for the first time,included two triangular and black patches on its gape,which appeared from four days old and became darker with age and growth.While this character also exists in nestlings of Oriental Cuckoo(C.optatus),it has not been found for other Cuculus species.Our results reveal cryptic aspects in the cuckoo-host egg color matching,which are not visible to the naked human eye,and indicate that high mimetic cuckoo eggs rejected by hosts,as determined by human observers in previous studies,might not be mimetic as birds see them. 展开更多
关键词 Egg color Egg matching Visual modeling spectrophotometer Cuculus saturatus Phylloscopus reguloides Robinson projection
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硅钼蓝光度法测定稻草原料及烧碱法制浆黑液的硅含量 被引量:26
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作者 童国林 陆琦 +1 位作者 汪陆鋆 周彩虹 《中华纸业》 CAS 北大核心 2005年第8期64-66,共3页
采用硅钼蓝光度法进行稻草原料或蒸煮黑液中的硅含量测定,其最大吸收波长为813nm,黑液中其它组分对硅钼蓝光度法测量结果没有影响。pH值对二氧化硅的溶解度影响很大,当pH等于10.3时,硅的溶解度发生突变。对蒸煮黑液硅含量采用硅钼蓝法... 采用硅钼蓝光度法进行稻草原料或蒸煮黑液中的硅含量测定,其最大吸收波长为813nm,黑液中其它组分对硅钼蓝光度法测量结果没有影响。pH值对二氧化硅的溶解度影响很大,当pH等于10.3时,硅的溶解度发生突变。对蒸煮黑液硅含量采用硅钼蓝法与重量法比较,测定结果基本一致。硅钼蓝法操作简单,检测时间短,结果准确可靠。 展开更多
关键词 硅钼蓝分光光度法 稻草 黑液 硅含量
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亚试剂固相萃取光度法测定水中微量铜的研究 被引量:4
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作者 孙海林 董学畅 +2 位作者 刘晓芳 尹家元 杨光宇 《云南化工》 CAS 2003年第4期43-45,共3页
 依据亚铜试剂与铜(Ⅰ)的显色反应以及WatersPorapak○RSep Park固相萃取小柱对显色配合物的固相萃取性能,建立了一种测定水样中μg/L级铜离子的新方法,在pH=4.5HAc NaAc缓冲介质中,吐温 80存在下,亚铜试剂与铜(Ⅰ)反应生成2∶1稳定配...  依据亚铜试剂与铜(Ⅰ)的显色反应以及WatersPorapak○RSep Park固相萃取小柱对显色配合物的固相萃取性能,建立了一种测定水样中μg/L级铜离子的新方法,在pH=4.5HAc NaAc缓冲介质中,吐温 80存在下,亚铜试剂与铜(Ⅰ)反应生成2∶1稳定配合物,该配合物可用WatersPorapak○RSep Park固相萃取小柱富集,小柱上富集的配合物用乙醇(内含1%醋酸)洗脱后用吸光光度法测定,可用于水样中μg/L级铜离子的测定。该方法应用于几种水样中微量铜离子的测定,结果令人满意。 展开更多
关键词 亚试剂 固相萃取光度法 测定 微量铜 2 2′-联喹啉
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Occurrence and distribution of metals and porphyrins in Nigerian coal minerals 被引量:4
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作者 OLAJIRE A A AMEEN A B +1 位作者 ABDUL-HAMMED M ADEKOLA F A 《燃料化学学报》 EI CAS CSCD 北大核心 2007年第6期641-647,共7页
The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μ... The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μg/g for Na whereas K, Mg, Mn, Ni, Cr, Zn, Pb, and Cu, which occurred at trace levels ranged from 673.73 μg/g for Mg to 2.97 μg/g for Mn. The results of the quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins (ca~0.96 μg/g) while Okpara has the lowest (ca~0.30 μg/g). The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared, and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3 440 cm~1~3 450 cm-1 and 1 640 cm-1~1 680 cm-1 , which are owing to the stretching vibrations of N ─ H and C─ C of aromatics, with C─ H out of plane (oop) bending vibrations at wavenumbers less than 900 cm-1, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at ~400 nm(Soret band) and at wavelength ranges of 535 nm~550 nm(β-band) and 565 nm~ 600 nm (α-band) for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed. 展开更多
关键词 METALS PORPHYRINS COALS TLC ultraviolet-visible and infrared spectrophotometerS
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Effect of drying methods on the discoloration of three major domestic softwood species in Korea 被引量:2
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作者 Ho-yang Kang 《Forestry Studies in China》 CAS 2006年第3期48-50,共3页
Japanese pine, Korean pine and larch are three major softwood species in Korea. Their colors are relatively light, thus easily discolored due to drying and UV irradiation. In this study, they were dried with five diff... Japanese pine, Korean pine and larch are three major softwood species in Korea. Their colors are relatively light, thus easily discolored due to drying and UV irradiation. In this study, they were dried with five different drying methods, steam treated and exposed to weathering. Their colors were measured using a spectrophotometer and comparisons made both among species and drying methods. For Japanese and Korean pines, high temperature dried and steam-dried specimens showed distinct color differences compared with the controls. Steam treatment discolored the dried specimens of Japanese and Korean pines but did not discolor those of larch. After weathering for 144 days the specimens of Japanese pine showed slight color differences among drying methods. 展开更多
关键词 DISCOLORATION drying method steam treatment WEATHERING spectrophotometer
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Alteration of chemical behavior of L-ascorbic acid in combination with nickel sulfate at different pH solutions in vitro 被引量:1
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作者 Shaheen A Maniyar Jameel G Jargar +2 位作者 Swastika N Das Salim A Dhundasi Kusal K Das 《Asian Pacific Journal of Tropical Biomedicine》 SCIE CAS 2012年第3期220-222,共3页
Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) com... Objective:To evaluate the alteration of chemical behavior of L-ascorbic acid(vitamin C) with metal ion(nickel) at different pH solutions in vitro.Methods:Spectra of pure aqueous solution of L-ascorbic acid(E mark) compound and NiSO_4(H_2O)(sigma USA) were evaluated by UV visible spectrophotometer.Spectral analysis of L-ascorbic acid and nickel at various pH(2.0, 7.0,7.4 and 8.6) at room temperature of 29℃ was recorded.In this special analysis,combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded.Results:The result revealed that λ_(max)(peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 run whereas at neutral pH 7.0,λ_(max) was 29S.4 run.In alkaline pH 8.6,λ_(max) was 295.4 nm and at pH 7.4 the λ_(max) of L-ascorbic acid remained the same as 295.4 nm.Nickel solution at acidic pH 2.0 was 394.5 nm,whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm.But at alkaline pH 8.6,λ_(max) value of nickel sulfate became 392.0 nm.The combined solution of L-ascorbic acid and nickel sulfate(6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm,respectively whereas at pH 7.0,L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm.At pH 7.4,L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6(alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm,respectively. Conclusions:Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH.Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical(HSc*) generation from the reaction of H,ASc + Ni(Ⅱ) is the cause of such alteration of λ_(max),value of L-ascorbic acid in the presence of metal nickel. 展开更多
关键词 L-ascorbic acid NICKEL PH Spectrum Chemical behavior Spectra UV visible spectrophotometer Peak wavelength Free radical VITAMIN C NICKEL SULFATE
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