Chemistry Research Papers - Academia.edu (original) (raw)

Recognizing the imperiled status of biodiversity and its benefit to human well-being, the world's governments committed in 2010 to take effective and urgent action to halt biodiversity loss through the Convention on Biological Diversity's "Aichi Targets". These targets, and many conservation programs, require monitoring to assess progress toward specific goals. However, comprehensive and easily understood information on biodiversity trends at appropriate spatial scales is often not available to the policy makers, managers, and scientists who require it. We surveyed conservation stakeholders in three geographically diverse regions of critical biodiversity concern (the Tropical Andes, the African Great Lakes, and the Greater Mekong) and found high demand for biodiversity indicator information but uneven availability. To begin to address this need, we present a biodiversity "dashboard"--a visualization of biodiversity indicators designed to enable tracking o...

- by
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- Engineering, Physics, Chemistry, Biology

Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O 2 electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foamingagent technique, or a templating method. All catalyst precursors were subjected to one or more heat treatments at 700-1050°C in an inert or reactive atmosphere. These catalysts underwent an identical set of electrochemical characterizations, including rotatingdisk-electrode and polymer-electrolyte membrane fuel cell (PEMFC) tests and voltammetry under N 2 . Ex situ characterization was comprised of X-ray photoelectron spectroscopy, neutron activation analysis, scanning electron microscopy, and N 2 adsorption and its analysis with an advanced model for carbonaceous powders. In PEMFC, several NNMCs display mass activities of 10-20 A g -1 at 0.8 V versus a reversible hydrogen electrode, and one shows 80 A g -1 . The latter value corresponds to a volumetric activity of 19 A cm -3 under reference conditions and represents one-seventh of the target defined by the U.S. Department of Energy for 2010 (130 A cm -3 ). The activity of all NNMCs is mainly governed by the microporous surface area, and active sites seem to be hosted in pore sizes of 5-15 Å. The nitrogen and metal (iron or cobalt) seem to be present in sufficient amounts in the NNMCs and do not limit activity. The paper discusses probable directions for synthesizing more active NNMCs. This could be achieved through multiple pyrolysis steps, ball-milling steps, and control of the powder morphology by the addition of foaming agents and/or sulfur.

- by Iris Herrmann
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- Chemical Engineering, Chemistry, Electrochemistry, Catalysis

The activation of the G-protein transducin (Gt) by rhodopsin (Rho) has been intensively studied for several decades. It is the best understood example of GPCR activation mechanism and serves as a template for other GPCRs. The structure of the Rho/G protein complex, which is transiently formed during the signaling reaction, is of particular interest. It can help understanding the molecular details of how retinal isomerization leads to the G protein activation, as well as shed some light on how GPCR recognizes its cognate G protein. The native Rho/Gt complex isolated from bovine retina suffers from low stability and loss of the retinal ligand. Recently, we reported that constitutively active mutant of rhodopsin E113Q forms a Rho/Gt complex that is stable in detergent solution. Here, we introduce methods for a large scale preparation of the complex formed by the thermo-stabilized and constitutively active rhodopsin mutant N2C/M257Y/D282C(RhoM257Y) and the native Gt purified from bovine...

- by Gebhard F X Schertler and +3
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- Engineering, Physics, Chemistry, Biology

Nosso interesse quimiotaxonômico sobre Neoraputia nos estimulou a examinar N. paraensis, visando a busca de alcalóides. As frações foram monitoradas via RMN 1 H e ESI-EM/EM e foram analisadas somente aquelas cujos espectros apresentavam características de alcalóides do ácido antranílico e flavonóides não isolados anteriormente. Foram isolados do caule os alcalóides flindersina,

- by Paulo Cezar Vieira
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- Chemistry, CHEMICAL SCIENCES

O presente trabalho teve por objetivos avaliar a composição de rizomas do lírio-do-bejo (Hedychium coronarium) e isolar e caracterizar seu amido, por meio de análises físicas e físico-químicas. A composição química dos grânulos de amido isolados dos rizomas também foi determinada, bem como o formato, tamanho, distribuição de tamanho de partícula por difração a laser, viscosidade de pasta em analisador rápido de viscosidade, poder de inchamento, índice de solubilidade em água, propriedade térmica por calorimetria diferencial de varredura e cristalinidade por difração de raios X. Observou-se que os rizomas apresentaram elevado teor de água e baixos teores de matéria graxa, carboidratos, cinzas, proteínas e fibras. Os rizomas de lírio-do-brejo apresentam-se inadequados para produção de amido, devido ao baixo teor de matéria seca (17,3%), com 21,97% de amido, bem como fibras longas e látex, que dificultam a extração do amido. O amido extraído apresentou pureza de 99,2%, com 37,2% de ami...

- by Wellington F E R R E I R A Moura
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- Mathematics, Physics, Thermodynamics, Chemistry

We show that the shape of electroluminescence transients in organic semiconductors can be conveniently used to obtain the diffusion constant D of injected charge carriers, enabling the study of generalized Einstein relationship under nonequilibrium conditions as a function of the electric field. The appearance of peak at the onset of transient is shown to be the signature of diffusive regime of transport. We demonstrate it for two representative materials, Alq 3 and polymer poly [2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene], with the focus on the role of hot carriers in transport and their diffusivity.

- by Yashowanta N. Mohapatra
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- Physics, Materials Science, Chemistry, Physical Chemistry
- by Ekasith Somsook
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- Chemistry, Inquiry Based Learning, Active Learning, Kinetics

Introduction: As high out-of-pocket healthcare expenses pose heavy financial burden on the families, Government of India is considering a variety of financing and delivery options to universalize health care services. Hence, an estimate... more

- by Shankar Prinja
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- Engineering, Physics, Chemistry, Health Care

The aim of this paper is to demonstrate that atomistic simulations can be used to evaluate the structure of mineral surfaces and to provide reliable data for forsterite surfaces up to a plane index of 2 using the code METADISE. The methods used to calculate the surface structure and energy which have more commonly been used to study ceramics are briefly explained as is a comparison with experimental data, most notable the crystal morphology. The predicted morphologies show that all the methods (Donnay-Harker, Attachment energies and equilibrium) show most of the surfaces that are expressed in observed crystals. The equilibrium morphology calculated from the relaxed surface energies is the only method which expresses the {201} surfaces and the {101} surfaces, which appear only upon relaxation. The more stable surfaces are shown to be those which have the highest surface density and more closely resemble close packed structures with highly coordinated surface ions and silicon as far from the surface as possible. The most stable surfaces the {100} which has alternating layers of MgO and SiO 2 terminating with an MgO layer. The structure is similar to the MgO {100} surfaces and has a similar energy (1.28 Jm Ϫ2 compared to 1.20). The second most stable are the {201} which have a stepped surface topology, but is also compact with a relaxed surface energy of 1.56 Jm Ϫ2. The results indicate that atomistic simulation is well suited to the prediction of surface structure and morphology although care must be taken in choosing potentials which model the structure and elastic properties accurately. Surface methodology The basic approach, used within the METADISE program (Watson et al. 1996), is to consider the crystal as a

- by Stephen Parker
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- Materials Engineering, Geochemistry, Chemistry, Surface Structure

Investigating the multidimensional integration between different microbiological kingdoms possesses potential toward engineering next-generation bionic architectures. Bacterial and fungal kingdom exhibits mutual symbiosis that can offer advanced functionalities to these bionic architectures. Moreover, functional nanomaterials can serve as probing agents for accessing newer information from microbial organisms due to their dimensional similarities. In this article, a bionic mushroom was created by intertwining cyanobacterial cells with graphene nanoribbons (GNRs) onto the umbrella-shaped pileus of mushroom for photosynthetic bioelectricity generation. These seamlessly merged GNRs function as agents for mediating extracellular electron transport from cyanobacteria resulting in photocurrent generation. Additionally, three-dimensional (3D) printing technique was used to assemble cyanobacterial cells in anisotropic, densely packed geometry resulting in adequate cell-population density for efficient collective behavior. These 3D printed cyanobacterial colonies resulted in comparatively higher photocurrent (almost 8-fold increase) than isotropically casted cyanobacteria of similar seeding density. An insight of the proposed integration between cyanobacteria and mushroom derives remarkable advantage that arises from symbiotic relationship, termed here as engineered bionic symbiosis. Existence of this engineered bionic symbiosis was confirmed by UV− visible spectroscopy and standard plate counting method. Taken together, the present study augments scientific understanding of multidimensional integration between the living biological microworld and functional abiotic nanomaterials to establish newer dimensionalities toward advancement of bacterial nanobionics.

- by SUDEEP JOSHI
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- Chemistry, Cyanobacteria, Nanotechnology, Additive Manufacturing

This document has been developed by a EURACHEM Working Group from a draft originally produced by LGC. The membership of the EURACHEM group is listed in Annex C. Ruling language The text may be freely translated into other languages, but where such action results in a dispute over interpretation, the guidance given in this English version is taken as being the definitive version. Copyright of the guidance presented in this guide is the property of the organisations represented by the working group members as listed in Annex C. All rights are reserved. This guidance may be downloaded for personal and non-commercial use, but no part of the guide may be distributed, published or stored in any retrieval system, in any media, by persons other than EURACHEM members, without the written consent of the EURACHEM Secretariats. Similarly, enquiries regarding the translation, production and distribution of new editions of this guide should be directed to the EURACHEM Secretariats This edition is...

- by Florent Vanstapel
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- Chemistry

The penetration of phenoxyethanol, dodecyl decaethoxylate and dodecyl monoethoxylate through rat skin was described in in vitro model systems using static cells with aqueous ethanol as receptor or flow-through diffusion cells with tissue culture medium as receptor. Absorption of 2-phenoxyethanol was similar in the static (64%) and flow-through diffusion cells (43%) suggesting that the choice of receptor fluid did not greatly influence prediction of penetration for this compound although the rate of absorption was higher in the static than flow-through cell, which reduced overall losses. A similar absorption was noted if evaporative losses were taken into consideration (static cell, 94%: flow-through diffusion cell, 85%). Dodecyl decaethoxylate absorption was influenced by the choice of receptor fluid; the absorption was 49.4% with aqueous ethanol, but was only 7% with tissue culture medium. However, using tissue culture medium as receptor, more material was located in the stratum corneum and skin than with aqueous ethanol. The highly lipophilic dodecyl monoethoxylate was rapidly absorbed into the lipophilic aqueous ethanol receptor fluid with total penetration of 102% at 8 hours. However, penetration to tissue culture medium was much lower in the flow-through diffusion cell. When stratum corneum, skin and receptor fluid were included in the estimate of penetration, total absorption was 33.3%, which increased to 66% when evaporative losses were considered. In conclusion, absorption profiles reflected the physicochemical properties of the ethoxylates, and the choice of receptor fluid appeared to be the most important factor in the choice of an in vitro model for predicting percutaneous absorption.

- by Peter Blain
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- Chemistry, Chromatography, In Vitro Toxicology, Elsevier

Ethylene is used commercially to hasten ripening of avocados, but the presence of ethylene in the storage atmosphere can increase the risk of physiological disorders. To investigate the short term effect of ethylene on avocado physiology, fruit were dipped in a low concentration ethephon solution. The ethephon treatment significantly increased the ethylene production rate of avocados after 6 h, compared to untreated fruit. After 6 h, the respiration rate of treated fruit increased significantly during the investigation while that of the untreated fruit did not show a significant increase from the initial measurement. Lipid peroxidation increased after dipping, reaching a peak after 4 h, and then declined to a level similar to untreated fruit. Mannoheptulose declined significantly during the 6 h investigation in both the untreated and treated fruit. It is concluded that avocado fruit can undergo significant physiological changes, and quality loss, in a short amount of time, which is exacerbated by exposure to ethylene.

- by Isa Bertling
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- Chemistry, Horticultural production

The authors regret that the original author list was incomplete. The full, corrected author list is presented herein to clarify the authorship of this article. In addition, the acknowledgements section should be revised to include the funding provided by the National Science Foundation. The corrected Acknowledgements is presented below. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

- by Sasidhar Varanasi*
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- Chemistry, RSC, Levulinic Acid, corn stover

The objective of the study was to determine if low intensity, high frequency vibration training impacted the musculoskeletal system in a mouse model of Duchenne muscular dystrophy, relative to healthy mice. Three-week old wildtype (n = 26) and mdx mice (n = 22) were randomized to non-vibrated or vibrated (45 Hz and 0.6 g, 15 min/d, 5 d/wk) groups. In vivo and ex vivo contractile function of the anterior crural and extensor digitorum longus muscles, respectively, were assessed following 8 wks of vibration. Mdx mice were injected 5 and 1 days prior to sacrifice with Calcein and Xylenol, respectively. Muscles were prepared for histological and triglyceride analyses and subcutaneous and visceral fat pads were excised and weighed. Tibial bones were dissected and analyzed by micro-computed tomography for trabecular morphometry at the metaphysis, and cortical geometry and density at the mid-diaphysis. Three-point bending tests were used to assess cortical bone mechanical properties and a subset of tibiae was processed for dynamic histomorphometry. Vibration training for 8 wks did not alter trabecular morphometry, dynamic histomorphometry, cortical geometry, or mechanical properties (P$ 0.34). Vibration did not alter any measure of muscle contractile function (P$0.12); however the preservation of muscle function and morphology in mdx mice indicates vibration is not deleterious to muscle lacking dystrophin. Vibrated mice had smaller subcutaneous fat pads (P = 0.03) and higher intramuscular triglyceride concentrations (P = 0.03). These data suggest that vibration training at 45 Hz and 0.6 g did not significantly impact the tibial bone and the surrounding musculature, but may influence fat distribution in mice.

- by Gordon Warren
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- Engineering, Physics, Chemistry, Skeletal muscle biology

This chapter is dedicated to the systems that add chemicals to the saline source water, which allow the conditioning of this water before its further pretreatment or direct reverse osmosis (RO) membrane separation. Source water conditioning is of critical importance for the efficient and cost-effective sedimentation and filtration of particulate and organic compounds contained in water as well as prevention of formation of scale on the RO membrane surface. This chapter describes the purpose and dosing of commonly applied source water conditioning chemicals such as coagulants, flocculants, scale inhibitors, biocides, acids, and bases.

- by Nikolay Voutchkov
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- Chemistry

Low-temperature plasma physics and technology are diverse and interdisciplinary fields. The plasma parameters can span many orders of magnitude and applications are found in quite different areas of daily life and industrial production. As a consequence, the trends in research, science and technology are difficult to follow and it is not easy to identify the major challenges of the field and their many sub-fields. Even for experts the road to the future is sometimes lost in the mist. Journal of Physics D: Applied Physics is addressing this need for clarity and thus providing guidance to the field by this special Review article, The 2012 Plasma Roadmap.

- by Jie Ge
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- Chemical Engineering, Physics, Materials Science, Solid State Physics

Phenyl and cyano substituent effects on the activation free energy of thermoneutral Cope rearrangements of 1,5-dienes are analyzed in terms of the activation free energies for formation of the two non-concerted mechanistic alternatives, cyclohexane-1,4-diyl and two allylic radicals. The experimental data, adjusted upwards in the case of 2-phenyl-1,5hexadiene, is reasonably correlated utilizing the harmonic mean values of the activation free energies and not some simple average of them or either one independently depending on which is lower. The latter two approaches appear to represent Centauric and Chameleonic models, respectively, as proposed by Doering. The harmonic mean is derived from consideration of the saddle point surface represented by a More O'Ferrall-Jencks diagram which appears to characterize the transition state structure and energetics of the Cope rearrangement. The conclusion from the correlation is that substitution of radical stabilizing groups alters the nature and stability of the transition state in accord with the position of substitution, and further substitution has an even greater effect if the position of substitution reinforces the change induced by the original substitution. If the position of substitution is opposed to the original substitution, the increase in stability of the transition state is attenuated.

- by Jahangir Emrani
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- Chemistry, Organic Chemistry

Extrusion-based bioprinting (EBB) is a rapidly growing technology that has made substantial progress during the last decade. It has great versatility in printing various biologics, including cells, tissues, tissue constructs, organ modules and microfluidic devices, in applications from basic research and pharmaceutics to clinics. Despite the great benefits and flexibility in printing a wide range of bioinks, including tissue spheroids, tissue strands, cell pellets, decellularized matrix components, micro-carriers and cellladen hydrogels, the technology currently faces several limitations and challenges. These include impediments to organ fabrication, the limited resolution of printed features, the need for advanced bioprinting solutions to transition the technology bench to bedside, the necessity of new bioink development for rapid, safe and sustainable delivery of cells in a biomimetically organized microenvironment, and regulatory concerns to transform the technology into a product. This paper, presenting a first-time comprehensive review of EBB, discusses the current advancements in EBB technology and highlights future directions to transform the technology to generate viable end products for tissue engineering and regenerative medicine.

- by Huanchun Chen
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- Chemistry, Organic Chemistry, Thymelaeaceae, Sesquiterpenes

The history of the Jewish Diaspora dates back to the Assyrian and Babylonian conquests in the Levant, followed by complex demographic and migratory trajectories over the ensuing millennia which pose a serious challenge to unraveling population genetic patterns. Here we ask whether phylogenetic analysis, based on highly resolved mitochondrial DNA (mtDNA) phylogenies can discern among maternal ancestries of the Diaspora. Accordingly, 1,142 samples from 14 different non-Ashkenazi Jewish communities were analyzed. A list of complete mtDNA sequences was established for all variants present at high frequency in the communities studied, along with high-resolution genotyping of all samples. Unlike the previously reported pattern observed among Ashkenazi Jews, the numerically major portion of the non-Ashkenazi Jews, currently estimated at 5 million people and comprised of the Moroccan, Iraqi, Iranian and Iberian Exile Jewish communities showed no evidence for a narrow founder effect, which did however characterize the smaller and more remote Belmonte, Indian and the two Caucasus communities. The Indian and Ethiopian Jewish sample sets suggested local female introgression, while mtDNAs in all other communities studied belong to a well-characterized West Eurasian pool of maternal lineages. Absence of sub-Saharan African mtDNA lineages among the North African Jewish communities suggests negligible or low level of admixture with females of the host populations among whom the African haplogroup (Hg) L0-L3 sub-clades variants are common. In contrast, the North African and Iberian Exile Jewish communities show influence of putative Iberian admixture as documented by mtDNA Hg HV0 variants. These findings highlight striking differences in the demographic history of the widespread Jewish Diaspora.

- by David Gurwitz
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- Engineering, Genetics, Physics, Chemistry

TALAT Lecture 1252- Corrosion and Corrosion Protection 1252.01.02 Corrosion Types ....................................................................................4 (a) General... more

TALAT Lecture 1252- Corrosion and Corrosion Protection
1252.01.02 Corrosion Types ....................................................................................4
(a) General corrosion.............................................................................................5
(b) Crevice corrosion.............................................................................................6
(c) Poultice corrosion ............................................................................................7
(d) Fretting corrosion (also called traffic marking)...............................................7
(e) Stress corrosion................................................................................................8
(f) Galvanic Corrosion ..........................................................................................9
(g) Pitting Corrosion............................................................................................10
(h) Intergranular corrosion and exfoliation .........................................................11
1252.02 Electrochemistry and Aluminium...........................................................11
1252.02.01 Introduction .........................................................................................11
1252.02.02 Kinetic Reactivity................................................................................12
1252.02.03 The Electrochemical Circuit ...............................................................13
1252.02.04 Aluminium as a Cathode.....................................................................13
1252.02.05 Aluminium as an Anode......................................................................14
1252.02.06 Summary of Electrolytic Corrosion .

- by Professor Dr. Loutfy H . Madkour
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- Chemistry, Corrosion Science, Corrosion
- by Dermot Diamond
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- Chemistry

Background: Arachidonic acid (AA; C20:4 n-6) and docosahexaenoic acid (DHA; C22:6 n-3) are important long-chain polyunsaturated fatty acids (LC-PUFA) in maintaining pancreatic beta-cell structure and function. Newborns of gestational diabetic mothers are more susceptible to the development of type 2 diabetes in adulthood. It is not known whether low circulating AA or DHA is involved in perinatally ''programming'' this susceptibility. This study aimed to assess whether circulating concentrations of AA, DHA and other fatty acids are associated with fetal insulin sensitivity or beta-cell function, and whether low circulating concentrations of AA or DHA are involved in compromised fetal insulin sensitivity in gestational diabetic pregnancies.

- by Carole Garofalo and +3
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- Engineering, Physics, Chemistry, Biology

In this paper, a study on the batch processing and characterization of microcellular foamed high-density polyethylene (HDPE/iPP) blends is reported. A microcellular plastic is a foamed polymer with a cell density greater than 109 cells/cm3 and fully grown cells smaller than 10 µm. Recent studies have shown that the morphology and crystallinity of semicrystalline polymers have a great influence on the solubility and diffusivity of the blowing agent and on the cellular structure of the resulting foam in microcellular batch processing. In this research, blends of HDPE and iPP were used to produce materials with variety of crystalline and phase morphologies to enhance the subsequent microcellular foaming. It was possible to produce much finer and more uniform foams with the blends than with neat HDPE and iPP. Moreover, the mechanical properties and in particular the impact strength of the blends were significantly improved by foaming.
(citation # 293)

- by Saeed Doroudiani, PhD, P.Eng.
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- Chemical Engineering, Physics, Chemistry, Physical Chemistry
- by Baneenah Amharib
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- Chemistry, Iodine, Lemna minor

Reagents are added in a specified order to a large beaker containing an aqueous solution of nickel sulfate. Complex ions of nickel (II) are prepared by using aqueous solutions of ammonia, ethylenediamine, dimethylglyoxime, and cyanide ion.

- by Fernanda Mora
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- Chemistry

Minkowski famously introduced the concept of a space-time continuum in 1908, merging the three dimensions of space with an imaginary time dimension $ i c t ,withtheunitimaginaryproducingthecorrectspacetimedistance, with the unit imaginary producing the correct spacetime distance ,withtheunitimaginaryproducingthecorrectspacetimedistance x^2 - c^2 t^2 ,andtheresultsofEinstein′sthenrecentlydevelopedtheoryofspecialrelativity,thusprovidinganexplanationforEinstein′stheoryintermsofthestructureofspaceandtime.AsanalternativetoaplanarMinkowskispace−timeoftwospacedimensionsandonetimedimension,wereplacetheunitimaginary, and the results of Einstein's then recently developed theory of special relativity, thus providing an explanation for Einstein's theory in terms of the structure of space and time. As an alternative to a planar Minkowski space-time of two space dimensions and one time dimension, we replace the unit imaginary ,andtheresultsofEinstein′sthenrecentlydevelopedtheoryofspecialrelativity,thusprovidinganexplanationforEinstein′stheoryintermsofthestructureofspaceandtime.AsanalternativetoaplanarMinkowskispace−timeoftwospacedimensionsandonetimedimension,wereplacetheunitimaginary i = \sqrt{-1} ,withtheCliffordbivector, with the Clifford bivector ,withtheCliffordbivector \iota = e_1 e_2 $ for the plane that also squares to minus one, but which can be included without the addition of an extra dimension, as it is an integral part of the real Cartesian plane with the orthonormal basis $ e_1 $ and $ e_2 $. We find that with this model of planar spacetime, using a two-dimensional Clifford multivector, the spacetime metric and the Lorentz transformations follow immediately as properties of the algebra. This also leads to momentum and energy being represented as components of a multivector and we give a new efficient derivation of Compton's scattering formula, and a simple formulation of Dirac's and Maxwell's equations. Based on the mathematical structure of the multivector, we produce a semi-classical model of massive particles, which can then be viewed as the origin of the Minkowski spacetime structure and thus a deeper explanation for relativistic effects. We also find a new perspective on the nature of time, which is now given a precise mathematical definition as the bivector of the plane.

- by Nicolangelo Iannella and +1
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- Engineering, Physics, Chemistry, Biology

Many molecular techniques have been developed to separate, isolate, and detect an individual molecule present in a sample. We have already seen how chromatography can help separate proteins from a mixture. Today, we will employ one of the most common techniques, electrophoresis (which is based on the movement of charged molecules within an electrical field, as you already know). The electrophoretic mobility of a charged molecule depends on the following factors: Net Charge: Charge of a molecule determines its direction of movement; Negative toward anode (+) and Positive toward cathode (-). Charge also affects its mobility; higher the charge the faster the molecule will migrate. Size: Smaller molecules travel faster through the pores, than larger molecules (frictional resistance). Shape: Highly structured molecules move slower than less structured molecules (frictional resistance). Electric Field Strength: Higher voltage increases the mobility of molecules in an electric field. Higher voltage also dramatically increases the heating effects on the molecules in that field. To increase the resolving power of this technique, support medias are used to act as molecular weight sieves. Two of the most common are agarose and polyacrylamide gels, which are cast either as horizontal or vertical slabs. Vertical slabs are formed between glass plates with defined spacers (0.75-1.5 mm). While agarose is usually used for separating nucleic acids, polyacrylamide is usually for protein separation because it is: 1) more versatile in pore size, 2) chemically inert, 3) transparent, and 4) stable over a wide pH, ion concentration, and temperature ranges. Therefore, polyacrylamide gel electrophoresis (PAGE) is the major technique employed for protein separation and analysis. Polyacrylamide gels are formed by polymerizing long chains of acrylamide monomer into long chains and cross-linking chains with N'-N'-methylene bisacrylamide (Note: Both acrylamide and bisacrylamide are potent neurotoxins, so wear gloves when handling liquids. Once polymerized the gel is non-toxic). Polymerization is caused by the generation of free radicals produced by ammonium persulfate (APS) in the presence of N,N,N',N'-tetramethylethylethylenediamine (TEMED). As with agarose, the separation of molecules within the gel is determined by the relative size of the pores that is determined by the total concentration of acrylamide (%T). As %T increases, the pore size decreases allowing you to resolve smaller molecules. You can pour a single percentage gel (such as a 7.5% acrylamide) or you can used a gradient gel (such as a 4%-20% acrylamide). Gradient gels are made by "floating" the lower % acrylamide solution on top of the higher % acrylamide solution. As the gel solidifies, a constant gradient of increasing acrylamide forms throughout the gel, making a more solid (less porous) matrix at the bottom. Using a gradient gel, a wide range of proteins can be separated on the gel without loosing the small proteins off of the bottom of the gel.

- by Ed Rybicki
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- Chemistry, Electrophoresis, SDS PAGE, Polyacrylamide

Objective: To determine the conductivity of various acid and the dissociation constant, a K for acetic acid 1 Theory 1.1 Electrical conductivity in solutions An electric current in solution is the result of the net movement of free ions in a specific direction. The current may be determined by measuring the resistance R between two similar inert electrodes immersed in the solution, as in the figure below where the oval region represents the solution; A represents the electrode area and l is the normal distance between the electrode planes. In actual practice an A.C. current with a low frequency of the order of approximately 1000 Hertz is used (to prevent electrolysis) in the measurement, and the components representing the resistance R in the complex impedance Z for the circuit is determined. We will always refer to this component (the real portion of the complex impedance) for what follows. The resistance is also dependent on the frequency (Debye-Falkenhagen effect). The theory and measurement here concentrates on low frequency measurements where the Onsager equation is meaningful. The fully automated measuring apparatus has been configured for low frequency measurement in accordance with the theory of electrolytes.

- by Collins Madu
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- Chemistry

An efficient and new but non-intrusive method to detect the fluctuation in gear load may be the motor current signature analysis (MCSA). In this paper, a multi-stage transmission gearbox (with and without defects) has been studied in order to replace the conventional vibration monitoring by MCSA. It has been observed through FFT analysis that low frequencies of the vibration signatures have sidebands across line frequency of the motor current whereas high frequencies of vibration signature are difficult to be detected. Hence, discrete wavelet transform (DWT) is suggested to decompose the current signal, and FFT analysis is carried out with the decomposed current signal to trace the sidebands of the high frequencies of vibration

Details of cerebellar afferent projections from the perihypoglossal nuclei were studied in the cat by means of retrograde axonal transport of horseradish peroxidase (HRP). Labeled cells were observed bilaterally (with a preponderance ipsilaterally) in nuclei intercalatus and praepositus hypoglossi following injections in various folia of the entire vermis, paraflocculus, flocculus, fastigial nucleus, and the nucleus interpositus anterior and posterior. Relatively high densities of labeled cells were found in nucleus intercalatus following injections in the anterior part of the vermis, whereas labeled cells in nucleus praepositus hypoglossi were found more frequently following injections in the posterior part of the vermis. Labeled cells in the nucleus of Roller were found only following injections in the anterior lobe vermis, posterior vermal lobules VI and VII, in the flocculus and in the nucleus interpositus anterior. No labeled cells could be detected in the three subdivisions of the perihypoglossal nuclei following HRP injections in crus I, crus II, paramedian lobule, and lateral cerebellar nucleus. The distribution of the HRP positive cells indicated the presence of a topographically organized projection from certain regions of the perihypoglossal nuclei to different parts of the cerebellum. The afferent and efferent connections of the perihypoglossal nuclei in relation to a functional role in eye and head movements are discussed.

- by Naiphinich Kotchabhakdi
- •
- Chemistry, Medicine, Cats, Cerebellum

C hemist Carl Djerassi published his first full-length autobiography just before his 70th birthday. Now, just weeks after his 91st, he delivers his second. Remarkably, In Retrospect does have new things to say. At an age when most scientists retire, Djerassi launched a second career as a novelist and playwright. And in the preface, he announces that In Retrospect is largely an "autopsychoanalysis", searching within his fiction for an understanding of his true self and motivations. The book is, however, much more wide-ranging and outward-looking than that implies, although Djerassi's powerful ego is ever-presentsometimes irritatingly, but often endearingly. Djerassi was born in Vienna to secular Jewish doctors who divorced, then remarried after Austria was annexed by Nazi Germany, so that Carl and his mother could escape to his father's native Bulgaria. From there, mother and son emigrated to the United States, where Djerassi learnt English and studied ferociously. In 1949, he joined the labs of the pharmaceutical company Syntex in Mexico City, where he led the research team that synthesized the first orally active steroid contraceptive compound, norethindrone. In 1959, he became a member of the chemistry faculty at Stanford University in California; he consolidated his reputation as a front-line chemist over three decades. Then he shifted his academic attention to outreach, before becoming a professor emeritus in 2002. Djerassi became enormously wealthy thanks to the soaring value of the Syntex stock acquired when he worked at the company, and he took up art (and house) collecting. Emotionally, his life was turbulent: he married three times, and had to face the tragedy of his daughter's suicide in 1978. His marvellous first autobiography, The Pill, Pygmy Chimps and Degas' Horse (Basic, 1992), covers this era in his life. In Retrospect goes over some of the same ground, using the prism of his other writingsrediscovering his Jewish identity through fictional characters in his books and plays, for example.

- by Alison Abbott
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- Psychology, Chemistry, Arts, Multidisciplinary

Laboratory Information System (LIS) streamlines workflow in the laboratory and eliminates time-consuming paperwork. The business today is getting increasingly pressured to be more productive and efficient with less traditional resources. If we look at a typical production process, for instance, the level of automation and optimization that has permeated into the production floor is quite astounding. Many industries have had a tremendous impact in bringing to the market the automation and optimization solutions to streamline -the production floor. The other ends of the spectrum are the back-office transaction oriented processes like Inventory Management, Materials Management, Financials and so on, Therefore a lab’s ability to process data quickly and its ability to disseminate that information efficiently throughout the plant is vital for the success of the production process. Laboratory Information Management System (LIMS) can help in managing the information flow within the lab and can be the modus operandi of connecting the lab with the rest of the organization. For instance, imagine all the information that is generated in a lab.

ABSTRACT
This work was carried out to investigate the chemical/mineral composition of the water extract of zobo (Hibiscus sabdariffa) drink using the modern atomic absorption spectrophotometer. Zobo drink is a popular drink in the Nigeria, especially in the northern part of Nigeria. The result of the analysis indicated that the drink is high in vital mineral nutrients required for the healthy growth by humans and for the proper metabolic processes to be adequately maintained. Zobo drink is high, as indicated in the result, in iron – a major component of the human haemoglobin, when compared with other leaf like the popular vegetable leaf known as awa (Piper methysticum).

- by Okafor Osita
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- Biochemistry, Chemistry, Conservation Biology, Molecular Biology
- by Ping Furlan
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- Chemistry, Chemical Education, Illustrations, Education

Waterborne epoxy coatings were commercially introduced about 40 years ago, mainly as an environmentally friendly replacement to solvent-borne epoxies in countries with strong environmental and worker safety regulations. Their growth was mainly driven by the desire to reduce the emission of organic solvents. This technology grew most rapidly in the concrete protection market, though there is also use over metal substrates and for some OEM applications. This paper will review the classification of waterborne epoxy coatings according to the type of epoxy resin being used. Type I systems are based on low molecular weight, liquid epoxy resin, and the curing agent typically doubles as the emulsifier for the resin. Type II systems are based on high molecular weight, solid epoxy resin dispersions. Properties like pot-life behavior, dry time and drying mechanisms (film formation) will be reviewed for both systems.

- by Antony J Williams
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- Chemistry, Chemistry Databases

I. STRUCTURE DU CHEVEU
II. PRODUITS D’HYGIENE CAPILLAIRE : LES SHAMPOOINGS
1. Composition et propriétés des molécules de base
2. Propriétés et résultats attendus
III. PRODUITS DE MODIFICATION DE LA FORME
1. Produits de modification temporaire
1.1. Extension du cheveu mouillé et séchage sous tension
1.2. Produits de maintien de la coiffure
1.2.1. Formulation des laques et des gels
1.2.2. Ingrédients et fonctions d’une laque
2. Produits de modification durable de la forme
2.1. Produits de permanente
2.1.1. Principe de la permanente
2.1.2. Les principes actifs utilisés en permanente
2.1.2.1. Les produits réducteurs
2.1.2.2. Les produits fixateurs
2.1.3. Les oxydoréductions de la permanente
2.1.4. Formulation d’un produit de permanente
2.2. Produits de défrisage
2.2.1. Principe du défrisage
2.2.2. Principaux composants et leurs fonctions
2.2.2.1. Défrisants thiolés
2.2.2.2. Défrisants alcalins

- by Marie-Paule ABATE SLH
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- Chemistry, Cosmetics and Fragrance Marketing, Chemicals, Beauty

This standard is issued under the fixed designation A380/A380M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

- by stefanie wang
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- Environmental Engineering, Chemical Engineering, Materials Science, Chemistry

Metallurgical Factors Affecting Corrosion in Petroleum and Chemical Industries
Abstract:
Humans have most likely been trying to understand and control corrosion for as long as
they have been using metal objects. With a few exceptions, metals are unstable in ordinary
aqueous environments. Certain environments offer opportunities for these metals to
combine chemically with elements to form compounds and return to their lower energy
levels. Corrosion is the primary means by which metals deteriorate. Most metals corrode on
contact with water (and moisture in the air), acids, bases, salts, oils, aggressive metal
polishes, and other solid and liquid chemicals. Metals will also corrode when exposed to
gaseous materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing
gases. The production of oil and gas, its transportation and refining, and its subsequent use
as fuel and raw materials for chemicals constitute a complex and demanding process.
Various problems are encountered in this process, and corrosion is the major one. Since
metals are the principal material suffering corrosive deterioration, it is important to develop
a background in the principles of metallurgy to fully understand corrosion. The control of
corrosion through the use of coatings, metallurgy, nonmetallic materials for constructions
cathodic protection and other methods has evolved into a science in its own right and has
created industries devoted solely to corrosion control. Metallurgical factors that affect
corrosion are chemical composition, material structure, grain boundaries, alloying elements,
mechanical properties, heat treatment, surface coating, welding and manufacturing
conditions. Understanding these factors are of great importance to decrease and control
corrosion problem in many industrial applications.

- by Professor Dr. Loutfy H . Madkour
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- Chemistry, Corrosion Science

The end of the Early Bronze Age, in other words the EBA III, is one of the significant turning points in the cultural history of the Anatolian Peninsula. Metal objects that indicate social class differences, advancements in architecture, and finds that point to connections with distant regions all demonstrate that a political structure began to emerge in Anatolia during this period. Parallel to these developments, especially with the increase in interregional relations, the use of new vessels indicates a novelty in eating and drinking habits. Tankards, bell-shaped cups and depas amphikypellon stand out within this group and are referred to as the new drinking vessels. In addition to these, it is noteworthy that beakers or goblets, and also container amphorae started to become widespread. All these types are considered to be associated with new drinking habits, and the new drink type is suggested to be wine. However, the suggestions proposed regarding the use of these vessels are not supported by any archaeometric studies until now. In this study, we share results from total lipid extraction analyses (TLE) performed by gas chromatography-mass spectrometry (GC-MS) on a group of depa vessels from the archaeological site of Küllüoba located in Eskişehir, Turkey, and re-evaluate at the possible purposes of these vessels. Biomolecules such as fatty acids, salicylic acids, organic acids, hydrocarbons, n-alkanes, and herbal steroids identified as a result of these analyzes provided the first direct evidence of the use of fermented products such as wine and herbal analgesics in Early Bronze Age Anatolia. Additionally, we present the first archaeological data of the period and the region regarding the use of salicylic acid.

- by Murat Türkteki
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- Archaeology, Prehistoric Archaeology, Chemistry, Anatolian Archaeology

RATIONALE: Agarwood is the resinous material harvested from threatened Aquilaria species. We investigated how many protonated 2-(2-phenylethyl)chromone ions were sufficient to make an accurate identification of agarwood. Analysis of 125 reference samples was carried out by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS). The identification criteria developed were applied to commercial samples. METHODS: We developed a technique that uses DART-TOFMS to detect 2-(2-phenylethyl)chromones. Additionally, we developed a set of criteria to infer the presence of Aquilaria in commercial samples of wood chips, sawdust, incense and liquids. Additionally, we examined other fragrant woods to determine if they contained a chemical profile that could be falsely identified as agarwood. RESULTS: Analysis of reference and commercial samples (n = 151) established that DART-TOFMS provides reproducible mass spectra that are useful for inferring the genus of suspected agarwood samples. We identified 17 ions which were useful for authenticating agarwood. Comparison of the number of chromone ions detected by direct analyses of dry wood chips versus eluent analysis of methanol-extracted wood showed that results were similar. Lastly, analysis of 25 scented woods of other species did not give false positive results. CONCLUSIONS: Reliable criteria for inferring agarwood include the presence of diagnostic ions, m/z 319.118 or 349.129, in addition to ten or more ions characteristic of 2-(2-phenylethyl)chromones. Wood anatomists challenged with difficult morphological identifications can use this tool to assist in their analyses. Published 2012. This article is a US Government work and is in the public domain in the USA.

- by Cady Lancaster
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- Earth Sciences, Chemistry, Mass Spectrometry, Flavonoids
- by JuanC. Thompson
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- Chemistry, Organic Chemistry

The aim of this work was to determine physicochemical parameters of winter savory (Satureja montana L.) honey produced in the Adriatic part of Croatia. Honey samples were collected from several production seasons and following physicochemical parameters were determined: water content, electrical conductivity, pH value, free acidity, sugar content, diastase activity and HMF content. The results of electrical conductivity (0.155 - 0.456 mS/cm), free acidity (16.1 - 35.8 mEq/kg) and diastase activity (16.3 - 45.8) varied in a wide range. Fructose/glucose and glucose/water ratios indicate moderate crystallisation rate of the honey.

- by Ljiljana Primorac
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- Chemistry

Denila, Richard V.
This study investigated the relationship of high school chemistry students’ motivation to learn and attitude towards chemistry with their chemistry academic achievement. This study was conducted at Norala National High School, Division of South Cotabato, for the school year 2009-2010.
The study made use of the correlation method with the questionnaires in Likert scale to gather the data. The instruments used were: Motivation questionnaire to learn (as adopted and modified by Ortiz, 1997) for determining the students’ motivation to learn chemistry; the Attitude Towards Science Scale (ATSS) by Wilkinson, 1979, as adopted by Alava, 2004 for determining the students’ attitude towards chemistry; and the Achievement Test in Chemistry for ascertaining the academic achievement of the third year chemistry students. The statistical tools used in the study were frequency count, percentage, the mean, standard deviation, and Pearson product-moment correlation (r) at 0.05 confidence level.
Findings showed that the third year students are motivated in achievement, in affiliation, in competence, and in maintenance to learn chemistry. Study show that they have the desire to learn the concepts and skills in chemistry. Collectively, the third year high school students’ have favorable attitude towards chemistry. The academic performance level of the of the third year students in high school chemistry is satisfactory. This indicates that the students are moderately competent in the knowledge and skills in chemistry. There is a statistically significant relationship between the third year students’ motivation to learn chemistry and their attitude towards chemistry. A statistically significant relationship exists between the third year students’ motivation to learn chemistry and their academic achievement in chemistry. Statistically there is a significant relationship between the third year students’ attitude towards chemistry and their academic achievement in chemistry.

- by Richard V Denila
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- Chemical Engineering, Chemistry, Organic Chemistry

This article is an extensive review of the literature on two component urethane systems that use water as a carrier. It generally covers the period from 1985 through 2000 with special emphasis on patent references since 1993. It includes both ambient temperature cured and baked systems containing unmodified and modified isocyanate building blocks. The main criterion for inclusion into this paper was that the finished urethane group containing polymer reaches its ultimate molecular weight after it is applied to a substrate, so that traditional latex-type materials are not emphasized.

- by Jolanta Gurtat
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- Chemistry, Collagen Cross-linking, Applications, Polyamines