Above-mentioned Concentration Research Articles

Assessment of sulfamethoxazole and oxytetracycline uptake and transformation in Eisenia fetida earthworms

The scientific community is becoming increasingly concerned about the recent detection of transformation products (TPs) of antimicrobials (AMs) and their presence in the food chain. There are growing concerns about the potential consequences on food safety and the proliferation of antimicrobial resistance. In this work, the transformation process of sulfamethoxazole (SMX) and oxytetracycline (OTC) in soil was thoroughly evaluated. For that purpose, soils were homogeneously contaminated at three concentration levels of SMX and OTC, independently, and samples were analysed after 7 and 14 days by Ultra High-Performance Liquid Chromatography coupled to a triple quadrupole mass spectrometer (UHPLC-MS/MS). The results have demonstrated a remarkable transformation, particularly noteworthy for SMX, as it exhibited an 89 % - 94 % decrease in concentration within the initial 7 days of the experiment. In addition, to assess whether terrestrial organisms would be able to accumulate the AMs, Eisenia fetida (E. fetida) earthworms were exposed to the above-mentioned concentration levels of AMs in soil. Both AMs were accumulated in the organisms after 14 days, but higher bioaccumulation factor values (BCF) were determined for SMX (0.52–17.84) compared to OTC (0.02–0.21) at all tested concentrations. The analyses were extended to search for TPs in earthworms and soils using a suspect screening approach. Concretely, by means of UHPLC-high resolution mass spectrometry (UHPLC-HRMS) three TPs were identified at 2a and 2b of confidence level. To the best of our knowledge, one SMX-TP and one OTC-TP were identified in earthworms and soil, respectively, for the first time in the present work. Earthworms did not experience weight loss or mortality in the presence of these AMs at levels found in the environment, but there was a decrease in riboflavin levels, which is linked to changes in the immune system. This study represents a significant advancement in understanding the impact of AMs in soil and their subsequent entry into the food chain. It also provides valuable insights into the potential effects of AMs and their TPs on organisms.

Synthesis of High Sn Content Ge1-x-ySixSny (0.1 < y < 0.22) Semiconductors on Si for MWIR Direct Band Gap Applications.

A systematic effort has been described to grow ternary Ge1-x-ySixSny semiconductors on silicon with high Sn concentrations spanning the 9.5-21.2% range. The ultimate goal is not only to produce direct band gap materials well into the infrared region of the spectrum but also to approach a critical concentration (yc) for which further additions of Si would decrease─rather than increase─the band gap. This counterintuitive behavior is expected as a result of the giant bowing parameter in the compositional dependence of the band gap associated with the presence of Si-Sn pairs. The growth approach in this study was based on a chemical vacuum deposition method that uses Si4H10, Ge3H8, and SnD4 or SnH4 as the sources of Si, Ge, and Sn, respectively. A fixed Si concentration near x = 0.05-0.07 was chosen to focus the exploration of the compositional space. A first family of samples was grown of Ge-buffered Si substrates. For Sn concentrations y < 0.12, it was found that the samples relaxed their mismatch strain in situ during growth, resulting in high Sn content films that had relatively low levels of strain and exhibited photoluminescence signals that demonstrated direct band gap behavior for the first time. The device potential of these materials was also demonstrated by fabricating a prototype photodiode with low dark currents. The optical studies suggest that the above-mentioned critical concentration is close to yc = 0.2. As the growth temperature was lowered in an effort to reach such values, Sn concentrations as high as y = 0.15 were obtained, but the films grew fully strained with compressive levels as high as 1.7%. To increase the Sn concentration beyond y = 0.15, a new strategy was adopted, in which the Ge buffer layer was eliminated, and the ternary alloy was grown directly on Si. The much higher lattice mismatch between the Ge1-x-ySixSny layer and the Si substrate caused strain relaxation right at the film/substrate interface, and the subsequent films grew with much lower levels of strain. This made it possible to lower the growth temperatures even further and achieve a comprehensive series of strained relaxed samples with tunable Sn concentrations as high as y = 0.21 (and beyond). The latter represent the highest Sn contents in crystalline Ge1-x-ySixSny attained to date and reach the desired yc = 0.2 range. The synthesized films exhibited significant thickness, allowing a thorough determination of composition, crystallinity, morphology, and bonding properties, indicating the formation of single-phase single-crystal alloys with random cubic structures. Further work will focus on optimizing the latter samples to explore the optical and electronic properties.

In silico, in vitro and in vivo studies: Dibutyl phthalate promotes prostate cancer cell proliferation by activating Forkhead Box M1 and remission after Natura-α pretreatment

Dibutyl phthalate (DBP) is widely used in perfumes, cosmetics, shampoos and medical devices. It is ubiquitous in the environment and greatly endangers people's health. Several studies have reported that being exposed to it can promote the development of lung cancer, breast cancer, hepatoma, and multiple myeloma. However, there are still few studies on the specific molecular mechanism and prevention methods of DBP promoting the progression of prostate cancer. This study, in silico, in vitro and in vivo, aims to explore the promoting effect of DBP on prostate cancer cell proliferation. In silico analysis, we obtained a set of DBP interactive genes by utilizing TCGA, CTD and GEO database. These genes are mainly enriched in cell cycle regulatory pathways and they have high degree of homogeneity. We found that these genes shared one transcription factor - Forkhead Box M1 (FOXM1) by performing Chip-X Enrichment Analysis (Version 3.0). FOXM1, once called the 2010 Molecule of the Year, aberrantly expressed in up to 20 kinds of tumors. In vitro experiments, we used DBP at concentrations of 10−8 M and 5 * 10−7 M to treat C4–2 and PC3 cells for 6 days, respectively. Cell viability was promoted significantly. When Natura-α was added in the background of above-mentioned concentration of DBP, this effect was significantly inhibited. In addition, we also found that DBP can interfering with the efficacy of enzalutamide therapy. The introduction of Natura-α can also reverse this phenomenon. In vivo, subcutaneous tumor formation experiments in nude mice, 800 mg/kg/day DBP can promote the growth of prostate cancer. This phenomenon was suppressed when Natura-α (100 mg/kg/day) was added. Based on the results of the above three levels, we confirmed that DBP can target FOXM1 to promote prostate cancer cell proliferation. Natura-α can reverse its cancer-promoting effect. This study provides new insights into the impact of DBP on prostate cancer.

Ethylated analogue of Zingerone: A new and eco-respectful preservative in cosmetics.

This article describes the eco-design of a new preservative in cosmetics based on bio-inspiration of natural extracts from traditional medicines. In order to reach the multiple specification targets, various structures have been synthesized and evaluated to select the one demonstrating broad antimicrobial spectrum with favorable environmental profile and application potential to a wide variety of formulas. In order to evaluate the antimicrobial activity of the synthesized structures, the method of the challenge test consisting in an artificial contamination of the sample with collection microbial strains and evaluation of the number of revivable microorganisms was used to select the most promising candidate. Validation of its antimicrobial potential was later confirmed on Gram positive and Gram negative bacteria, yeast and mold with measurement of its Minimum Inhibitory Concentration (MIC) in comparison with known preservatives. Environmental impact assessment of the selected candidate was achieved with the help of ready biodegradability and aquatic ecotoxicity tests performed according to appropriate Organization tes a strfor Economic Co-operation and Development (OECD) and European Union (EU) guidelinesy. Bio-inspired from turmeric and ginger extracts, an ethylated analog of Zingerone (EZ) with the chemical name 4-(3-ethoxy-4-hydroxyphenyl)butan-2-one demonstrates the strongest activity on Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans. Moreover, EZ shows a solubility in water two times higher than that of Zingerone thus increasing its interest as a potential preservative. Finally, its assessment of ready biodegradability and aquatic ecotoxicity in OECD-EU tests with a favorable environmental profile confirms its unique interest and fully justifies its use in cosmetic formulas as an eco-respectful preservative. Bio-inspiration based on technologies without noteworthy side effects but also on eco-design, particularly through the use of measures of potential environmental impact very upstream of a development, are two fundamental elements for the launching of new eco-friendly cosmetic ingredients. This approach has thus validated the strong potential of EZ as a preservative of eco-respectful formulas. The selection of EZ is also a very good example of the achievement of two key objectives targeted by cosmetic companies for the development of a novel active ingredient: environmental performance and technical performance.

Synthesis and characterization of metal-based nanoparticles and their effect on seed quality parameters of American varieties of cotton

Cotton seeds are poor germinator than other crops because of high sensitivity towards insect pests and other biotic and abiotic stresses during germination process. Various researches are done to increase seed quality parameters of cotton seeds but application of nanoparticles was never used for same. Literature regarding interaction of seed quality of cotton and nanotechnology is not available till date. Seeds of two American varieties (H 1300 and H 1098-i) of cotton were treated with different concentration (0 ppm, 50 ppm, 100 ppm, 200 ppm and 400 ppm) of three different nanoparticles (Zinc oxide nanoparticles, silver nanoparticles and Titanium dioxide nanoparticles) and their bulk form Zn(NO3)2·4H2O, AgNO3 and [Ti{OCH(CH3)2}4], respectively. Seeds were also nanoprimed with above-mentioned concentration of nanoparticles. Effect of seed treatments was observed for germination percentage and seed vigour indices in laboratory conditions and for seedling establishment and speed of germination in field conditions. Nanoparticles were synthesized by chemical method and characterization of nanoparticles was done by FESEM, HRTEM, UV/Vis analysis and FTIR. Characterization of nanoparticles confirmed that the size of chemically synthesized nanoparticles was in nano range. The average particle size of ZnONPs, AgNPs and TiO2NPs was 36.25 nm, 69.35 nm and 39.40 nm, respectively. It was witnessed that dissimilar concentration of nanoparticles showed non-significant effect on seed quality in laboratory as well as seedling establishment and speed of emergence in field condition. Nanopriming with nanoparticles is more suitable for seed treatment over seed treatment with nano form (powder form) and bulk form. It was also noticed that ZnONPs and TiO2NPs increased seed quality parameters but silver had slightly negative effects. Maximum seed germination and seed vigour indices in laboratory and seedling establishment and speed of emergence in field condition was found when seeds were nanoprimed with 400 ppm of ZnONPs and 200 ppm of TiO2NPs. It could be concluded that problem of low germinability and vigour of cotton seeds could be minimized by seed treatment with nanoparticles.

Effect of Electrospinning Parameters on the Fiber Diameter and Morphology of PLGA Nanofibers.

Poly lactic-co-glycolic acid (PLGA) has been widely investigated for various biomedical applications, such as craniofacial bone regeneration, wound dressing and tissue engineering. Electrospinning is a versatile technology used to produce micro/nanoscale fibers with large specific surface area and high porosity. The aim of the current study is to prepare PLGA nanofibers using electrospinning for guided tissue regeneration/guided bone regeneration applications. The objective of this study is to determine the appropriate electrospinning parameters such as applied voltage, flow rate, spinneret-collector distance and polymer solution concentration for preparation of PLGA fibrous membrane and their effect on the mean fiber diameter of the electrospun fibers. PLGA pellets were dissolved in Hexafluoroisopropanol (HFIP) in various concentrations overnight using a bench rocker. The resulting PLGA solution was then loaded into a syringe and electrospinning was done by maintaining the other parameters constant. Similarly, various fibrous mats were collected by altering the specific electrospinning parameter inputs such as applied voltage, flow rate and spinneret-collector distance. The morphology of the fibrous mats was characterized using Scanning Electron Microscope. The mean fiber diameter was assessed using ImageJ software and the results were compared using one-way ANOVA. We obtained bead-free uniform fibers with various tested solution concentrations. One-way ANOVA analysis demonstrated significant variation in mean fiber diameter of the electrospun fibers with altering applied voltage, solution concentration, flow rate and spinneret-collector distance. The above-mentioned electrospinning parameters and solution concentration influence the mean fiber diameter of electrospun PLGA nanofibers.

1931년 ‘長江 大水災’ 救濟와 國際協力: 國民政府 救濟水災委員會의 外國人 人力과 海外 財源

In this paper, the elements of “international cooperation” involved in relief work for ‘the Great Flood Disaster in 1931’ of ‘the National Flood Relief Commission(NFRC)’ were examined in terms of staffing and funding. In terms of personnel organization, a large number of foreign experts participated in the NFRC. Not only quantitatively but also qualitatively, it played a very important role at every strategic point. “International cooperation” in the composition of human resources has become a foundation for the NFRC to promote modern changes in the relief system and methods of relief. Regarding the financial resources, there was no other way in China to find the necessary resources for the relief of flood damage, so it was more and more desperate to find a breakthrough in international cooperation. Finally, the main financial resources consisted of “American Wheat Loan” (58.9%), “Special Surtax of Customs” (25.2%), and “Relief Fund for Flood Victims” (13.3%). “American Wheat Loan” is a in-kind foreign debt, which was negotiated by the Chinese government and the US government for about a month or so. It is a matter of course that the source of financial resources is abroad. “Special Surtax of Customs” is also taxed on foreign imported goods, and in reality, it can be collected only with the implicit consent (cooperation) of the foreign powers, and the source is also deeply related to the abroad. “Fund raising” was obtained from overseas through “international cooperation”, as donations from Overseas Chinese made up 21.9%, and support from foreign governments and private sectors accounted for 18.3%. Therefore, the total amount of financial resources procured from abroad through “international cooperation” exceeds 90% of the total. Without “international cooperation,” the NFRC could not have financed it, and the response of the Chinese government would have been extremely limited, and it would not have been able to find a new relief system or methods. The reason why “international cooperation” was able to become active was also due to the high international interest in the “Great Flood in 1931.” The appeals of the Chinese government and private organizations contributed to this, as well as detailed reports from foreign media. In addition, the ‘international cooperation network’, which was normally operated, also helped. Of course, it wasn''t the first time that international aid was made to save China''s disaster. There has been ‘international cooperation’ since quite early on, and we can see the ‘international cooperation’ of 1931 as the Nanjing Nationalist Government has aggregated and maximized the existing flow. Also, this ‘international cooperation’ was not one-sided. In another aspect, however, the fact that the above-mentioned concentration of overseas financing well shows the weakness of China''s finances at the time. In other words, it shows one aspect of ‘structured external dependence.’

Applicability of capillary electrophoresis-frontal analysis for displacement studies: Effect of several drugs on l-tryptophan and lidocaine binding to human serum albumin.

The effective concentration of a drug in the blood, i.e. the concentration of a free drug in the blood, is influenced by the strength of drug binding onto plasma proteins. Besides its efficacy, these interactions subsequently influence the liberation, absorption, distribution, metabolism, excretion, and toxicological properties of the drug. It is important to not only determine the binding strength and stoichiometry, but also the binding site of a drug on the plasma protein molecule, because the co-administration of drugs with the same binding site can affect the above-mentioned concentration and as a result the pharmacological behavior of the drugs and lead to side effects caused by the change in free drug concentration, its toxicity. In this study, the binding characteristics of six drugs with human serum albumin, the most abundant protein in human plasma, were determined by capillary electrophoresis-frontal analysis, and the obtained values of binding parameters were compared with the literature data. The effect of several drugs and site markers on the binding of l-tryptophan and lidocaine to human serum albumin was investigated in subsequent displacement studies which thus demonstrated the usability of capillary electrophoresis as an automated high-throughput screening method for drug-protein binding studies.

تأثير تراكيز مختلفة من السكر في بيئة زراعة الأنسجه على نمو نبات الورد صنف ساره (Sara)

The effect of adding different sugar concentrations of five treatments (T1, T2, T3, T4, T5) on rose growth CV Sarah in vitro was carried out in the Sudan University Laboratories. Data were collected for plant height, number of branches, number of leaves, and fresh weight. Statistical analysis was conducted using a completely randomized design, to find the least significant difference to compare between treatment means for MS (Murashige and Skoog) medium. Data analysis showed that the application of sugar at concentrations of 15, 30, and 45gms gave the highest means for the different growth parameters and fresh weight at a significant level, whereas the addition of sugar at 60gms concentration and sugar-free gave no significant increases. This showed clearly that addition of sugar was essential for plant growth, greater concentrations gaviz 60gm negative results, Addition of sugar at the above-mentioned concentration from 15mg,45gm to parameters studied the growth media in vitro gave a positive increase in rose growth.

Probing the Effect of Cardiolipin on the Redox-Partner Recognition between Cytochrome C2 and Cytochrome Bc1 Complex

Cytochrome c (cyt. c) and cytochrome bc1 (bc1) complex are redox proteins that participate in the electron transport chain of the mitochondria, with cyt. c shuttling electrons from bc1 complex to complex IV. Cyt. c and bc1 complex reside in the inner membrane of the mitochondria, which is rich in the negatively-charged cardiolipin (CL). CL concentration in mitochondria varies upon different physiological conditions, and in some cases, a depletion of CL leads to a reduced bc1 complex activity. In this study, the redox-partner recognition between cyt. c and bc1 complex is examined using molecular dynamic (MD) and Brownian dynamics (BD) simulations with variations in CL concentration and salinity. First, MD simulations were performed to equilibrate cyt c2 and bc1 complex with membranes of different CL concentrations to obtain atomistic representations of their in situ configurations. Then, for each CL concentration, the electrostatic potential profile as well as hydrophobic interactions under different salinities were determined; to serve as input parameters for BD simulations. Then, for each redox state of cyt. c2 and that of bc1 complex, as well as for each of the above-mentioned CL concentration, a set of 10 independent 200 microsecond BD simulations were performed to sample the binding likelihood between the two proteins. Our result shows that a match between the redox state of cyt. c2 and that of bc1 complex promotes the binding of the two proteins in all different conditions. However, the ability of cyt. c2 to distinguish bc1 complex from the membrane surface is susceptible to the corresponding electrostatic potential profile, which can be significantly modified by variations in CL concentration and salinity.

Pigments content in Сhlorella vulgaris under the influence of the sodium selenite and the ions of metals

We investigated the content of pigments in Chlorella vulgaris Beij. (Chlorophyta) under the influence of sodium selenite in concentrations based on Se4+ 0.5, 5.0, 10.0 and 20.0 mg/dm3 during one, three and seven days and under the influence of the simultaneous action of selenite in concentrations 10 mg Se4+/dm3 and ions of Zn2+, Mn2+, Co2+,Cu2+, Fe3+ in concentrations 5.00, 0.25, 0.05, 0.008 and 0.002 mg/dm3over seven days. This research was carried out to establish the conditions for obtaining algal lipidis substance enriched with selenium and biogenic metals in the aquaculture. The content of pigments was determined spectrophotometrically, the cellular walls were separatedby centrifuge in the percoll gradient and investigated microscopically. The pigments content in the Ch. vulgaris increased by 1.5–2.5 times in comparison with the control sample under the influence of 10 mg Se4+/dm3 with and without metal ions, in all variants of experimental influence due to binding of SeО32– with proteins and lipids. We found that selenium was included in all lipid fractions (triacylglycerols, dyacylglycerols, phospholipids, nonetherified fatty acids); the maximum amount of selenium-containing lipids wasrecorded in chloroplasts. The increase in the contents of carotenoids caused by the actions of experimental factors played an exceptional role in the mechanism of antioxidant protection that prevents destruction of chlorophyll and, accordingly, increases its amount in cells. Changes in the functioning of the photosynthetic apparatus of Ch. vulgaris affect the whole complex of metabolic transformation. Thus, the successful cultivation of chlorella, enriched with selenium and biogenic metals, is possible within seven days under the influence of 10 mg Se4+/dm3 and the above-mentioned concentration of metal ions.

Prediction model of sulphur distribution ratio between CaO–FeO–Fe2O3–Al2O3–P2O5 slags and liquid iron over large variation range of oxygen potential during secondary refining process of molten steel based on ion and molecule coexistence theory

A thermodynamic model for predicting sulphur distribution ratio LS between CaO–FeO–Fe2O3–Al2O3–P2O5 slags and liquid iron, i.e. the ion and molecule coexistence theory (IMCT)–LS model, has been developed for slags in a large variation range of slag oxidisation ability based on the IMCT. The developed IMCT–LS model has been verified with measured data of oxygen, phosphorus and sulphur distribution equilibria between the slags and liquid iron from the literature. The results indicate that the desulphurisation reaction is mainly controlled by reaction (CaO)+[S] = (CaS)+[O] in the reducing zone with the optimised standard molar Gibbs free energy change of ; the desulphurisation reaction is dominated by reaction (FeO)+[S] = (FeS)+[O] in the oxidising zone with the reported standard molar Gibbs free energy change of . The influence of CaO on the desulphurisation ability of the slags can be counteracted by that of FetO because higher CaO content corresponds to lower FetO content in the slags. An asymmetric V type relationship between sulphur distribution ratio LS and the mass action concentration ratio or or or , or the mass percentage ratio (%FeO)/(%CaO) or (%Fe2O3)/(%CaO) or (%FetO)/(%CaO) or the simplified complex basicity or optical basicity can be established for the slags equilibrated with liquid iron in a temperature range from 1811 to 1927 K (1538 to 1654°C). The abovementioned mass action concentration ratios or mass percentage ratios of various iron oxides to basic oxide CaO can be recommended to represent the comprehensive effect of iron oxides FetO and basic oxide CaO on desulphurisation ability of the slags.

Effect of arsenic trioxide and 5-aza-2'-deoxycytidine on SHP-1, JAK3, TYK2 gene expression in K562 cells

This study was purposed to explore the effects of a methylation inhibitor arsenic trioxide (As2O3, ATO) and 5-Aza-2'-deoxycytidine (5-aza-CdR) on the expression of JAK-STAT signal transduction pathway in family members JAK3, TYK2 and hematopoietic cell phosphatase SHP-1 in chronic myeloid leukemia cell line K562 and their roles in pathogenesis of leukemia. The K562 cells were divided into 3 groups:single drug-treated group, combined 2 drugs-treated group, group without drug treatment as control. The concentration of 5-aza-CdR were 0.5, 1, 2 µmol/L; the concentration of ATO was 1, 2.5, 5 µmol/L; the concentration of combined drugs was ATO 1 µmol/L + 5-aza-CdR 0.5 µmol/L, ATO 2.5 µmol/L + 5-aza-CdR 1 µmol/L, and ATO 5 µmol/L + 5-aza-CdR 2 µmol/L. The K562 cells were treated with above-mentioned concentration of drugs for 24, 48 and 72 hours, then the total RNA of cells was extracted, the JAK3, TYK2 and SHP-1 expressions were detected by real-time quantitative-PCR. The results showed that after the K562 cells were treated with ATO and 5-aza-CdR alone and their combination, the expression of SHP-1 mRNA increased, the expressions of JAK3 mRNA and TYK2 mRNA decreased along with increasing of concentration and prolonging of time, displaying the concentration and time-dependency. The SHP-1 negatively related with JAK3 and TYK2. The effect of SHP-1 on JAK3 was significantly higher than that on TYK2. It is concluded that when the K562 cells are treated with ATO and 5-aza-CdR alone and their combination, the expression of SHP-1 is up-regulated and the expressions of JAK3, TYK2 are down-regulated in concentration-and time-dependent manners, moreover the ATO and 5-aza-CdR show synergies demethylation effect. The SHP-1 gene exert effect possibly through inhibiting the JAK/STAT pathway, the JAK3 is affected more than TYK2, the JAK3 may exert more important role in TAK/STAT pathway.

Toxicological Effects of the Antibiotic Oxytetracycline to an Indian Major Carp Labeo rohita

Oxytetracycline (OTC), an antibacterial agent, is extensively used in aquaculture practices all over the world. Despite its use, the toxicity of OTC to freshwater fish has been scarcely investigated. In this study, Labeo rohita were exposed to different concentrations (20, 40, 60, 80, 100, and 120 mg L(-1)) of OTC. Based on the survival-to-mortality ratio, an 80 mg L(-1) concentration was selected for sublethal toxicity analysis. Fish were exposed to the above-mentioned concentration for a period of 25 days, during which fish were killed at the end of every 5 days to analyse certain hematological and enzymological parameters. During the exposure period, a mixed trend was observed in hemoglobin (Hb), hematocrit, mean cell volume, mean cellular Hb, and mean cellular Hb concentration, whereas decreased red blood cell count and increased white blood cell was noted. A biphasic trend was observed in the enzymatic levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase in the vital organs (gill, liver and muscle) of fish. The alterations of these parameters lead to the conclusion that these parameters may be used as biomarkers in monitoring OTC toxicity in aquaculture and fisheries farms.

Kinetics of absorption of carbon dioxide into aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol

This work presents the kinetics of the reaction of CO 2 with aqueous 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) solutions at 303, 313, and 323 K within the amine concentration range of 0.179–1.789 kmol m −3 using a wetted wall column absorber. The reaction was described by zwitterionic mechanism to interpret the kinetic data. The reaction order was found to be in between 1.0 and 1.1 with respect to amine for the above-mentioned concentration range. The kinetic rate parameters were calculated and presented at each experimental condition. The second order rate constants, k 2, were obtained as 532.7, 1096, and 2380 m 3 kmol −1 s −1 at 303, 313, and 323 K, respectively with activation energy of 65.2 kJ mol −1. A parametric sensitivity analysis was carried out to study the effect of different key system parameters on the rate of CO 2 absorption.

Absorption of Carbon Dioxide into Aqueous Solutions of 2-Piperidineethanol: Kinetics Analysis

This work presents the kinetics of the reaction of CO2 with aqueous 2-piperidineethanol (2-PE) solutions at 303, 313, and 323 K within the amine concentration range of 0.14−1.13 kmol m−3 using a wetted-wall column absorber. The reaction was described by zwitterionic mechanism to interpret the kinetic data. A qualitative 13C NMR analysis has been carried out for 2-PE solution in D2O after reaction with CO2, which has indicated the formation of bicarbonate ion. The reaction order was found to be in between 1.10 and 1.12 with respect to amine for the above-mentioned concentration range. The kinetic rate parameters were calculated and presented at each experimental condition. The second-order rate constants, k2, were obtained as 696, 1147, and 2047 m3 kmol−1 s−1 at 303, 313, and 323 K, respectively, with an activation energy of 45.2 kJ mol−1.

Adsorption layer and foam film properties of mixed solutions containing β-casein and C 12DMPO

The interrelations between adsorption layer properties and surface forces in thin foam films of protein/surfactant mixtures were investigated. The adsorption from β-casein/dodecyl dimethyl phosphine oxide (C 12DMPO) mixed solutions was studied by Profile Analysis Tensiometry (PAT). The adsorption of protein/surfactant mixtures at the air/water interface is of competitive nature. The obtained adsorption isotherms suggest a gradual displacement of the protein molecules from the interface with increasing surfactant concentration. Foam films were studied by microinterferometry, originally introduced by Scheludko and Exerowa. The obtained experimental results show that the composition of the mixed adsorption layers changes with increasing amount of added surfactant. At a certain mixing ratio the corresponding foam film thickness decreases dramatically. This change happens above the surfactant concentration where the surface tension of the protein–surfactant mixtures approaches the values obtained for the respective pure surfactant solutions. The thickness, refractive index and adsorbed amount of the respective adsorption layers were determined by ellipsometry. These results correlate with the above-mentioned PAT and foam film data. The refractive index and adsorbed amount decrease monotonically and reach values close to those for pure surfactant solutions. On the contrary, a continuous increase can be observed in the layer thickness up to the above-mentioned concentration, indicating the formation of a more diffuse layer at the air–water interface formed by β-casein and C 12DMPO molecules upon increase of surfactant concentration. For foam films the electrolyte concentration can change the equilibrium thickness of the films and the Π(h)-isotherms significantly.

Crystal growth and below-bandgap optical absorption studies in InAs for non-linear optic applications

Abstract Indium arsenide (InAs) is a direct bandgap semiconductor ( E g =0.36 eV) and is well suited for non-linear optic (NLO) applications. The NLO applications require high linear optical transmission for below-bandgap energy photons in the material. Due to this stringent criterion, there is a need for understanding the fundamental optical absorption mechanisms in the material as well as correlating them with the presence of native defects and impurities introduced during the crystal growth. In this paper, we will present the experimentally measured and theoretically analyzed infrared absorption in an undoped and Te-doped n-type InAs in the wavelength region of 4–20 μm for horizontal Bridgman grown crystals. Transmission measurements at 300 K were performed on samples of undoped and Te-doped n-type InAs with carrier concentration in the range of 2.6×10 16 –1.7×10 17 cm −3 . The dependences of various absorption mechanisms as a function of wavelength have been presented. Free carrier absorption by electrons is found to be the dominant absorption mechanism at longer wavelengths ( λ >9 μm) for all the samples. At shorter wavelengths ( λ n i =1×10 15 cm −3 ), the inter-valence band transitions by free holes contributes significantly to the total absorption. Unique fitting parameters have been deduced to theoretically explain the infrared absorption mechanism in InAs for the above-mentioned carrier concentration range.

Peculiarities of coexistence of heavily twinned phases in the (1 − x)Pb(Mg1/3Nb2/3)TiO3-xPbTiO3 solid solutions at 0.23 ≤ x ≤ 0.30

The conditions for elastic matching of heavily twinned ferroelectric phases R3m, Cm, and Pm in (1 − x)Pb(Mg1/3Nb2/3)TiO3-xPbTiO3 solid solutions at room temperature are analyzed within the concept of zero-net-strain planes. The results of the investigations are presented in the form of diagrams of the concentration parameters of individual types of domains (mechanical twins) of coexisting phases separated by interfaces being zero-net-strain planes. The conditions for constancy of the above-mentioned concentration parameters at the coexistence of the R3m — Cm, R3m — Pm, and Cm — Pm phases in the range of molar concentrations 0.23 ≤ x ≤ 0.30 are discussed.

Comparison of in vitro antioxidant and antiradical activities of L-tyrosine and L-Dopa

Phenolic compounds are interesting because of their antioxidant properties. In the present study, the antioxidant properties of L-tyrosine as a monophenolic and L-Dopa as a diphenolic amino acid were investigated by using different antioxidant assays: (i) 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH*) scavenging; (ii) 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolorization assay; (iii) total antioxidant activity by ferric thiocyanate method; (iv) ferric ions (Fe3+) reducing power; (v) superoxide anion radical (O2*-) scavenging; (vi) hydrogen peroxide (H2O2) scavenging, and (vii) ferrous ions (Fe2+) chelating activities. Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the same concentration (20 microg/mL), L-tyrosine and L-Dopa showed 30.6 and 67.9% inhibition of lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, BHA, BHT, alpha-tocopherol and trolox indicated inhibitions of 74.4, 71.2, 54.7 and 20.1% on the peroxidation of linoleic acid emulsion, respectively, at the above-mentioned concentration. In addition, L-tyrosine and L-Dopa had an effect on DPPH radical scavenging, ABTS radical scavenging, superoxide anion radical scavenging, H2O2 scavenging, total ferric ions reducing power and metal chelating on ferrous ions activities.