Chemistry

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Analysis of Cr Atoms Three-Dimensional Deposition Characteristics
(Scientific Research, 2011-09) Yang, Hua-Lei; Zhang, Wen-Tao; Yang, Jian
The semi-classical model is used to simulate the three-dimensional trajectory and deposition distribution of the chromium atoms in the Gaussian laser standing wave field using the Runge-Kutta method, and then the three-dimensional deposition stripes are also given, besides, the effects of atomic beam divergence, chromatic aberration and spherical aberration on deposition structure are also analyzed.
Analysis of the Behavior of Local Cooking Utensils in Tap Water, Salt Tap Water and Vegetable Oil According to the Temperature
(Scientific Research, 2013-12) Ndiaye, Mamadou Babacar; Bec, Sandrine; Coquillet, Bernard; Cissé, Ibrahima Khalil
In Senegal the aluminum scrap are mainly recycled kitchen utensils [1]. The craftsmanship poses the problem of the quality of finished products [1] especially when we know they are used for everyday cooking. Given that none of these alloys should not be used to make cooking utensils if we refer to the EN 601 standard in July 2004, which refers to this regard [1], this study aims at analyzing behavior of these alloys reconstructed in three settings (tap water, vegetable oil and salt water more than 3 grams per liter), chosen for their importance in Senegalese cuisine. Significant loss of material was observed mainly by intergranular corrosion. It would be interesting that additional studies be conducted to examine the impact of the daily use of these alloys on the health of Senegalese.
Anisotropy of Photocatalytic Properties in Nanostructured Photocatalysts
(Scientific Research, 2016-04) Wang, Huanchun; Qiao, Lina; Xu, Haomin; Lin, Yuanhua; Shen, Yang; Nan, Cewen
Energy band engineering and the nature of surface/interface of a semiconductor play a significant role in searching high efficiency photocatalysts. Actually, the active facets, morphology controlling, especially the exposed facets modulation of photocatalysts during preparation are very desirable. In order to achieve high photocatalytic performance, intrinsic mechanism of such anisotropic properties should be fully considered. In this review, we mainly emphasis on the latest research developments of several extensively investigated photocatalysts and their anisotropic photocatalytic properties, as well as the correlation between effective masses anisotropy and photocatalytic properties. It will be helpful to understand the photocatalytic mechanism and promote rational development of photocatalyst for wide applications.
Application of Conjugated Organic Polymers for Photovoltaic's: Review
(2018-01) Tadesse, Tsegaye
Photovoltaic effect is the emergence of a voltage between electrodes attached to a solid or liquid system up on shining light on to this system. Conjugated polymer is a molecular entity whose structure is represented as a system of alternating single and double bonds which give rise to their semi-conductor properties. Conjugated polymers are used for photovoltaic devices because, intrinsically stable up on photoexcitation with visible light, High absorption cross-section for photon harvesting, Tunable band gap with in the entire visible spectral range and High yield of charge generation when mixed with electron acceptor materials. The important physical process in the energy conversion process that take place in polymers for photovoltaic cells are; Absorption of a photon of light by photoactive material and generation of excitons, diffusion of excitons in conjugated polymers, dissociation of charge carriers (electron-hole pair) at the donor-acceptor interface in to free carriers, transport of free carriers towards the electrodes, and extraction of the charge carriers at the respective electrode interfaces. The efficiency of converting solar to electrical energy by a solar cell depends on the band gap of the light absorbing semiconductor. Band gap (Eg) is the difference in energy between the HOMO and LUMO and there by the maximum amount of energy required for an excitation or is the energy difference between the edges of the conduction band and valence band. The power conversion efficiency is a function of band gap. For device architectures of conjugated polymer based photovoltaic cells; there are three types Single layer photovoltaic cell, Bilayer hetero junction photovoltaic cell and Bulk hetero junction Photovoltaic cell.
Applications of Infrared Spectroscopy in Analysis of Organic Aerosols
(Scientific Research, 2018-01) Cao, Gang; Yan, Yuan; Zou, Xuemei; Zhu, Rongshu; Ouyang, Feng
This paper reviews the studies of using FTIR to investigate the components of aerosols produced in smog chamber experiments and collected in atmosphere. The fact that aerosols are mixture of small amount of countless individual compounds makes the analysis of aerosol constituents very challenging. Although a number of advanced instruments have been applied to the chemical characterization of aerosol components, the majority of aerosol components, particularly the organics, remain unknown. Being supplemental to the traditional quantitative instruments, FTIR has been recently used either individually or combining with other analytical instruments to characterize the components of aerosol particles. This paper aims to show how FTIR is applied to analysis of organic aerosols in current literature and to summarize the FTIR characteristic peak frequencies that are widely seen in the FTIR measurement of organic aerosols. It will be greatly helpful to researchers whose studies are focused on the analysis of aerosol components.
Aptamers—A Promising Approach for Sensing of Biothreats Using Different Bioinformatics Tools
(Scientific Research, 2013-11) Sharma, Anamika; Sharma, Rakesh Kumar
Intentional release of pathogens or biotoxin against humans, plants, or animals is an impending threat all over the world. Continuous monitoring of environment is required for their detection. These signals can help to distinguish whether the bioattack has occurred or not. Biosensors utilise biological response including different biochemical reactions, antigen antibody reactions, electrochemical reactions, aptameric reactions etc. The currently available biosensors have a limit of detection, specificity and less linearity which affect their sensitivity. Aptamers are single stranded oligonucleotides binding species which are capable of tightly binding to their distinguishing targets. They are evolved from random oligonucleotides pools by using different strategies. These are capable of conscientiously distinguishing their target ligands. They have high sensitivity and a wide range of detection limit. The versatility of nucleic acid based methods allowed for the design of specific aptamer sequences, typically on the order of 10 to 30 base pairs in length, identifying the different biothreat agents in the environment. By using different bioinformatics tools we can design RNA aptamers for toxins of lectin family.
Aromatic Bromination in Concentrated Nitric Acid
(Scientific Research, 2014-04) Andrievsky, Alexander M.; Lomzakova, Vera I.; Grachev, Mikhail K.; Gorelik, Mikhail V.
Action of bromine in concentrated nitric acid allows carrying out mono- and polybromination of moderately deactivated aromatic compounds. 4-Chloronitrobenzene and isophthalic acid turnes into 3-bromo-4-chloronitrobenzene and 5-bromoisophthalic acid at reaction with bromine in concentrated nitric acid at 20˚C whereas in absence of bromine in the same conditions 4-chloro-1, 3-dinitrobenzene and 5-nitroisophthalic acid are formed accordingly. Presence of bromine in concentrated nitric acid changes nitrating capacity to brominating one. Terephthalic acid and phthalic anhydride at heating with bromine in concentrated nitric acid can be transformed to appropriating tetrabromo substituted compounds.
Assessment of Heavy Metals Immobilization in Artificially Contaminated Soils Using Some Local Amendments
(Scientific Research, 2013-07) Abdel-Kader, Noha H.; Shahin, Reda R.; Khater, Hasan A.
Three alluvial soil samples with different textures were artificially polluted with chloride solutions of Cd, Pb, Co and chromate solution for Cr. The aqua-regia extracted concentration ranges in the artificially polluted soils were 1134 - 1489 mg·kg−1 for Pb, 854 - 938 mg·kg−1 for Cr, 166 - 346 mg·kg−1 for Co and 44 - 54 mg·kg−1 for Cd. The aqua-regia extracted metals were the highest in the spiked clay soil due to its high adsorption capacity. Rock phosphate (PR), limestone (LS) and Portland-cement (Cem) were mixed with the spiked soils at 1% and 2% rates (w/w) and incubated at 30 C for 2, 7, 14, 30, 60, 150 and 360 days. The extracted DTPA metals significantly decreased with different magnitudes with increasing the incubation period accompanied by increases in both pH and EC. The data showed that cement (Cem) treatment dropped the DTPA-Pb from @ 1000 to @ 400 mg·kg−1 in all the studied soils (60% decrease) in the first 2 months while it gradually decreased from 400 to 200 mg·kg−1 (20% decrease) in the next 10 months. Limestone (LS) and rock phosphate (PR) materials were relatively less effective in lowering DTPA-Pb after 12 months of incubation. The data showed also that cement (Cem) treatment was the most effective one in lowering DTPA-Cd by @ 60% as compared to the un-amended soils after 12 months of soil incubation. Extractable DTPA-Co and Cr showed consistent decreases with time down to nearly 50% of un-amended soils due to the effect of the added amendments after 12 months of incubation with superior reductions for the cement treatment in all the investigated soils. The statistical analysis confirmed that in all the studied metals and treatment, cement treatment (Cem) was significantly the most effective in lowering the DTPA extracted metals as indicated from LSD test. It was found that up to 73% and 57% of the applied Pb and Cd, respectively, were fixed by only 1% cement. However, the present study showed that from the practical and economic points of view, that 1% Cement was the best treatment to immobilize Pb and Cd from all the artificially polluted soils.
Azido-meta-hemipinic Acid: An "Introverted" Acid?
(2018-02) Jin-Young, Choi; Jisoo, Kim; Jinyong, Shin; Minsu, Lee; Tae-Ho, Yoon; Sunmook, Lee
Biocomposite materials consisting of Poly-L-Lactic-Co-Glycolic Acid (PLGA) and Hydroxyapatite (HA) were synthesized and mechanical properties have been observed by carrying out the fatigue test, for which accelerated tests have been conducted such that 20%, 30% and 40% of the yield strength have been applied in a repeated mode until a crack occurred on the load-applied points of test specimen. Based on the fatigue test results, the lifetime of test specimen (B10 life) was estimated. It was found that Weibull distribution (shape parameter=8.79) was the most proper one to describe the failure data obtained from the accelerated fatigue tests. B10 life at 5% of yield strength was estimated to be 335,764 cycles (Confidence Level=95%, lower limit) by applying an inverse power model.
A Benchmark Study on the Properties of Unsubstituted and Some Substituted Polypyrroles
(2015-11) Ibeji, Collins U; Adejoro, Isaiah A; Adeleke, Babatunde B.
The geometric, thermodynamic, electronic and absorption properties of Pyrrole and some of its derivatives have been carried out using CCSD/6-311++G(d,p)/STO-3G, TD-DFT and DFT/B3LYP/6-31G(d) from monomer to five repeating units. Substitution by a methyl group at C3 and functional groups at C4 cause small changes in atomic distances. The estimated inter-ring bond length based on Badger's rule of 1.41 Å indicates that the average structure is about 30% quinoid. The geometries indicates that strong conjugate effects and effective aromatic structure are formed in the order Pyrrole>MPCam>MPC. The oligomers of simulated compounds have been extrapolated to polymer through second-degree polynomial-fit equation with r2 value ranging from 0.96-0.99. Calculated band gap of pyrrole, which is 2.9 eV, significantly correlates with the experimental value which ranges from 2.9-3.2 eV and this corresponds to π-π* transition energies. Natural bond orbitals of polypyrrole reveals that the wavefunctions contain dynamic correlations (single reference), closed shell character while substituted polypyrrole are multireference (static correlation), open shell character.
Bio-Renewable Sources for Synthesis of Eco-Friendly Polyurethane Adhesives—Review
(Scientific Research, 2017-11) Gadhave, Ravindra V.; Mahanwar, Prakash A.; Gadekar, Pradeep T.
Bio-renewable sources used during manufacturing of polyurethane (PU) adhesives have been used extensively from last few decades and replaced petrochemical based PU adhesive due to their lower environmental impact, easy availability, low cost and biodegradability. Bio-renewable sources, such as vegetable oils (like palm oil, castor oil, jatropha oil, soybean oil), lactic acid, potato starch and other bio-renewable sources, constitute a rich source for the synthesis of polyols which are being considered for the production of “eco-friendly” PU adhesives. Various bio-renewable sources for synthesis of bio-based PU adhesives and their potential applications are discussed in this review. This paper will focus on the progress of research in bio-based materials for adhesive application.
Biodiesel Production from Neem Seed (Azadirachta indica) Oil Using Calcium Oxide as Heterogeneous Catalyst
(2018-04) Banu, Hannah Danjuma; Shallangwa, Tsodiya Banu; Innocent, Joseph; Thomas, Odey Magu; Hitler, Louis; Sadia, Ahmed
Biofuel is an alternative and environment friendly source of energy, originated by the use of fossil fuels and have led to a notable growing demand from the last few decades. As biodiesel are usually acquired from renewable sources like vegetable and animal oils, for example coconut oil is extracted from the coconut and then characterized for further usage. The aim of this study is to investigate the production of biodiesel from neem oil and to characterize the parameters that affect biodiesel performance. The Biodiesel was produced using trans-esterification process resulting in the values of saponification 191 mg KOH/g, iodine 10 mgl2/g, acid 14.0 mg KOH/g, density 0.91 g, viscosity 23 mm2/s and flash point 266°C. The biodiesel was also characterized and showed that the it has density of 820 kg/m3, viscosity 3.5 mm2/s, saponification value 91 mg KOH/g, iodine value 8.9 mgl2/g, acid content 30.8 mg KOH/g and flash point 110°C. The physicochemical properties obtained were also compared to standard biodiesel in the range of ASTM specifications.
Bioethanol Production from Rice Straw Enzymatically Saccharified by Fungal Isolates, Trichoderma viride F94 and Aspergillus terreus F98
(Scientific Research, 2014-06) Abo-State, Mervate A.; Ragab, Ahmed M. E.; EL-Gendy, Nour Sh.; Farahat, Laila A.; Madian, Hekmat R.
Egypt faces a high population growth rate nowadays, which demands for an increase in agricultural production efficiency. Consequently, agricultural field residues will increase. Rice straw is one of the main agriculture residues in Egypt. So this study was performed on rice straw as a resource for production of bioethanol. Eight microbial isolates, five yeasts and three fungi were isolated from rice straw. Yeast isolates were selected for their ability to utilize different sugars and cellulose. Chipped and grinded rice straw was subjected to different pretreatment methods physically through steam treatment by autoclaving and different doses of gamma γ irradiation (50 and 70 Mrad). Autoclaved pretreated rice straw was further enzymatically treated throughout solid state fermentation process by different fungal isolates; F68, F94 and F98 producing maximum total reducing sugars of 12.62, 13.58, 17.00 g/L, respectively. Bioethanol production by separate microbial hydrolysis and fermentation (SHF) process of rice straw hydrolysate was performed by the two selected fungal isolates; Trichoderma viride F94 and Aspergillus terreus F98 and two yeast isolates (Y26 and Y39). The two yeast isolates have been identified by 18S, RNA as Candida tropicalis Y26 and Saccharomyces cerevisiae Y39. SHF processes by F94 and Y26 produced 45 gallon/ton rice straw while that of F98 and Y39 produced 50 gallon/ton rice straw.
Biological Activities of Resveratrol against Cancer
(2018-04) Kim, Soo Mi; Kim, Sung Zoo
Resveratrol (RSV) is a polyphenolic compound naturally found in grapes, peanuts, and berries. Considerable research has been performed to determine the benefits of RSV against various human diseases, especially cancer. Despite numerous studies on the effect of RSV on cancer, correct understanding of its mechanism is still far from certainty. This review summarizes the recent results on the molecular mechanisms and pathways of actions of RSV against major cancers. According to investigations accomplished worldwide, RSV targets pathways such as cell cycle progression, autophagy, apoptosis, angiogenesis and invasion/metastasis to attenuate cancer progression mediated through PI3K/Akt/mTOR, Wnt, ROS, NF-κB, BAX/Bcl-2, AMPK, ERK, MAPK signaling pathway. Considering the sideeffects and data of clinical trials, RSV can be used for its maximum benefits in human diseases. Available published data provide strong clues on the impact of RSV on cancer management.
Biophysical EPR Studies Applied to Membrane Proteins
(2015-11) Sahu, Indra D.; Lorigan, Gary A.
Membrane proteins are very important in controlling bioenergetics, functional activity, and initializing signal pathways in a wide variety of complicated biological systems. They also represent approximately 50% of the potential drug targets. EPR spectroscopy is a very popular and powerful biophysical tool that is used to study the structural and dynamic properties of membrane proteins. In this article, a basic overview of the most commonly used EPR techniques and examples of recent applications to answer pertinent structural and dynamic related questions on membrane protein systems will be presented.
Bubble Formation in Helicoidal DNA Molecules
(2016-11) Tabi, Conrad Bertrand
Wave interaction is addressed the framework of the helicoidal Peyrard-Bishop model of DNA. The model is first reduced to a set of coupled nonlinear Schrodinger equations via the multiple scale expansion. Modulational instability analysis shows that multi-breather trains exist in large regions of instability, while trains of one-humped breathers are observed for the single excitation mode. Analytical solutions are proposed, where single modes are proposed to described DNA respiration and coupled waves rather describe the bubbles observed in experiments. These bubbles are shown to be more effective under weak helicoidal coupling. The process of strand separation is also discussed. PACS number(s): 87.14.E-, 87.15.H-, 05.45.Yv, 05.45.-a
Cancer Risk Due to the Natural Radioactivity in Cigarette Tobacco
(Scientific Research Publishing, 2016-07) Ridha, Ali A.; Hasan, Hasan A.
Thirty-one samples of cigarettes have been collected from local markets of different types of origins. The samples were selected according to a survey distributed to smokers by paper and digital survey to see the most heavily traded among smokers and in addition to a number of questions to see how the awareness and the culture of smokers in diseases caused by smoking and considered this study the first survey in Iraq. The aim of this research is to assess the number of cancer cases due to cigarette smoking. Through the use of High-Purity Germanium system (HPGe) (efficiency 40%) we determinated the radionuclides in cigarette tobacco. The average values were (14.86 ± 3.76, 10.84 ± 3.13, 1050.64 ± 47.57) Bq/kg for Ra-226, Th-232 and K-40, respectively, and the excess lifetime of cancer risk values ranged from 0.54 to 130 at average of 76 per million person per year. Raeq values varied from 18.50 to 87.21.4 Bq/kg with an average value of 39.51 Bq/kg for tobacco samples. The annual effective dose (HE) varies from 16.38 μSv/y to 44.69 μSv/y with an average value of 24.97 μsv/y. The Annual Gonadal Dose Equivalent (AGDE) varies from 0.3 to 0.64 (mSv/y) with an average value of 0.42 for all tobacco samples under investigation.
Cation Sensing of Pyridoxal Derived Sensors Towards Fe (II) Ion in Pure Aqueous Solution
(2017-12) Darshana, Rana; Rana, Aniruddhasinh M; Sahoo, Suban K
A novel sensor (L) was synthesized using Schiff base reaction of pyridoxal with orthophenylene diamine and was characterized by various spectroscopic techniques such as FTIR, 1H NMR and Mass spectrometry. The cation recognition ability of the synthesized sensor was investigated by experimental (UV-VIS, IR and 1H NMR) and theoretical (B3LYP/6-31G**) methods. Among the tested anions, the developed sensor showed a naked-eye detectable color change from colorless to yellow and spectral changes in the presence of Fe(II) due to the formation of hydrogen bonded complexes with these cations followed by the partial deprotonation of sensor. With a micromolar detection limit, the developed sensor proved highly efficient and can be utilized for the colorimetric detection of Fe(II) ions.
Cellulose Microfibril from Banana Peels as a Nanoreinforcing Fillers for Zein Films
(Scientific Research, 2012-05) Phiriyawirut, Manisara; Maniaw, Parichat
Cellulose microfibril (CMF) was the extraction with acid mixture from peel of Musa sapientum Linn type of banana (Kluai Nam Wa). The fibrous-shape of CMF interconnected weblike structure with the average diameter 26 nm were observed by TEM. In order to prepare zein/CMF nanocomposite films, 16 wt% zein solution was prepared by dissolved in 80% ethanol aqueous solution which contain glycerol 20% w/w. The suspension of CMF and zein solution was mixed with 0% - 5% weight fractions of solid CMF in zein matrix. The morphology of the zein films is more roughness by increased amount of cellulose microfibrils. It was found that as CMF content increase from 0 to 5 wt% results in increasing tensile strength and Young’s modulus of zein nanocomposite films. The highest strength obtains at 4 wt% CMF.
The Chain Reaction of Atmospheric Nitrogen Oxidation, Initiated by an Electric Discharge in Air
(2015-11) Fedotov, V. G.; Fedotova, EYa
The data, concerning to the nitrogen oxidation reaction, initiated by electrical discharge, are reviewed in this article. The reviewed data lead to conclusion that critical concentrations of NO molecules and NO3 radicals can be achieved in course of discharge in air at some special conditions, thereafter avalanche-like rise of reaction velocity is observed. At explosion conditions the oxidation of nitrogen proceeds until full exhaustion of atmospheric oxygen in the reaction zone. Explosion like kinetics of nitrogen oxidation results in high concentration of electronically excited molecules NO(B 2Π), it forms conditions for laser generation in the blue region of the spectrum. The generation of this kind was observed. The proposed mechanism of chain reaction explains all the experimental data.

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