Kinds Of Reactions Research Articles

Applications of Chitosan and Its Derivatives Supported Transitional Metal Catalysts in Organic Reactions

Due to its good coordination ability to the metal compounds, chitosan and its derivatives can be used as a kind of good catalysts carrier. Recently, the catalytic properties of chitosan and its derivatives supported metal catalyst have been attracted more attentions. Based on the kind of reactions, the applications of chitosan and its derivatives supported metal catalysts in the catalytic asymmetric reaction, allylic substitution, coupling, addition, oxidation, reduction and some other reactions are reviewed.

RDH13L, an Enzyme Responsible for the Aldehyde-Alcohol Redox Coupling Reaction (AL-OL Coupling Reaction) to Supply 11-cis Retinal in the Carp Cone Retinoid Cycle

Cone photoreceptors require effective pigment regeneration mechanisms to maintain their sensitivity in the light. Our previous studies in carp cones suggested the presence of an unconventional and very effective mechanism to produce 11-cis retinal, the necessary component in pigment regeneration. In this reaction (aldehyde-alcohol redox coupling reaction, AL-OL coupling reaction), formation of 11-cis retinal, i.e. oxidation of 11-cis retinol is coupled to reduction of an aldehyde at a 1:1 molar ratio without exogenous NADP(H) which is usually required in this kind of reaction. Here, we identified carp retinol dehydrogenase 13-like (RDH13L) as an enzyme catalyzing the AL-OL coupling reaction. RDH13L was partially purified from purified carp cones, identified as a candidate protein, and its AL-OL coupling activity was confirmed using recombinant RDH13L. We further examined the substrate specificity, subcellular localization, and expression level of RDH13L. Based on these results, we concluded that RDH13L contributes to a significant part, but not all, of the AL-OL coupling activity in carp cones. RDH13L contained tightly bound NADP(+) which presumably functions as a cofactor in the reaction. Mouse RDH14, a mouse homolog of carp RDH13L, also showed the AL-OL coupling activity. Interestingly, although carp cone membranes, carp RDH13L and mouse RDH14 all showed the coupling activity at 15-37 °C, they also showed a conventional NADP(+)-dependent 11-cis retinol oxidation activity above 25 °C without addition of aldehydes. This dual mechanism of 11-cis retinal synthesis attained by carp RDH13L and mouse RDH14 probably contribute to effective pigment regeneration in cones that function in the light.

Formation of polyphenyl chains through hierarchical reactions: Ullmann coupling followed by cross-dehydrogenative coupling

From an interplay of UHV-STM imaging and DFT calculations, we have illustrated on-surface formation of polyphenyl chains through a hierarchical reaction pathway involving two different kinds of reactions (Ullmann coupling and cross-dehydrogenative coupling), which will provide a deeper understanding of on-surface chemical reactions and an alternative and efficient strategy to fabricate desired surface molecular nanostructures.

Unusual food allergy: Alioidea allergic reactions overview.

Allergic reactions can cause by several aliments and foods. Symptoms usually appear after ingestion, several hours after consumption or even almost immediately. Various food allergies can lead to serious diseases and in some cases to death, so the priority for people suffering from them should be prevention and completely avoiding foods that cause this kind of reactions. Allergy to Alioidea is one of the probable causes of contact dermatitis, gingival and oculonasal diseases and asthma. In this review, we will focus on the increasing incidence of allergy to foods of common use like onions and garlic. In the last ten years, the world production of onions and garlic has increased of at least 25%. People make large use of them, not only in cookery but also from a therapeutic point of view. Their growing use is producing more and more specific, insidious and sometimes serious medical conditions, which highly influence the quality of life of patients. Medical practitioners should be able to recognize immediately these disorders in order to diagnose them quickly and accurately, avoiding unnecessary tests and treatments. We will also describe new patents for detecting food allergens.

ChemInform Abstract: Recent Advances in Transition‐Metal‐Catalyzed C—CN Bond Activations

AbstractReview: [43 refs.

Carbon- and Nitrogen-Based Porous Solids: A Recently Emerging Class of Materials

Abstract In this account, the emergence of a new family of porous solid-state materials based on carbon and nitrogen is discussed. This started with the observation that carbon nitride, a polymeric material with a composition close to C3N4, is not only unexpectedly thermally and chemically stable, but a semiconductor at the same time and able to catalyze a variety of chemical reactions, such as Diels–Alder cyclizations, oxidations, and photochemical water splitting. Carbon nitride is however already sufficiently reviewed but related materials with similar potential have essentially been not sufficiently covered. The remaining structures are manifold and cover the range from on the one hand covalent triazine frameworks (CTFs) as new semiconducting porous solid-state materials to the other porous nitrogen-doped carbons (NdCs) as catalysts which are known to be applicable in a variety of electrocatalytic reactions. CTFs are porous polymeric frameworks constituted of triazine rings and other aromatic rings. Chemical binding motifs and crystal structures can be used to control the band structure of such an (organic) solid-state material. Porous NdCs are usually made by adding nitrogen sources to classical carbonization recipes, and they are attracting a lot of interest because of their catalytic activity for electrochemical processes, such as oxygen reduction reaction (ORR). This account will summarize state-of-the-art work on those systems being next-generation catalysts for different kinds of reactions, which are affordable and high-performance catalysts with unique principle for emergence of catalytic activities, combining theoretical and experimental studies together with basic and applied science in a range of scientific fields from chemistry to physics. Indeed, the first exploration of the above materials as candidates for components of fuel cells and rechargeable metal–air batteries are discussed.

Theoretical studies on the taking off of oxygen-containing functional groups in lignite model compounds

The removal reaction mechanism of different kinds of oxygen-containing functional groups in lignite was investigated,benzoic and phenol were chosen as model compounds. Density function theory( DFT) and DFT-based B3 LYP method along with mixed basis sets 6-311 + G( d,p) were applied in all calculations. The results suggest that removal approaches are different from different kinds of oxygen-containing functional groups and the taking off energy is also different. According to the reaction activation energy of different kinds of reactions,autocatalysis reaction of structure unit containing carboxyl is the easiest. Taking account of the influence of water molecular to the reaction,formic acid and glycerin were studied as model compounds. The results show that water molecular can reduce the reaction activation energy and accelerate the reaction process,the best catalytic effect is achieved with one or two water molecular. The effects of Na+,K+and their carboxylates to the reaction were studied on glycerin as well. The results suggest that Na+and K+can reduce the reaction activation energy by forming complexes with glycerin,which stabilizes the transition state structure. Na+has a better catalytic effect to the reaction. Comparing with sheer ions,the catalytic effects of carboxylate can't reach that good. However,potassium carboxylate's catalytic effect doesn't change a lot,while the catalytic effect of sodium carvoxylate has a significant decrease.

Microwave-Assisted Topochemical Conversion of Layered Titanate Nanosheets to {010}-Faceted Anatase Nanocrystals for High Performance Photocatalysts and Dye-Sensitized Solar Cells

The {010}-faceted anatase nanocrystals with controllable crystal size and morphology were synthesized by microwave hydrothermal treatment of layered titanate nanosheet solutions. The nanostructures and formation reaction mechanism of TiO2 nanocrystals were investigated using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and selected-area electron diffraction. Their photocatalytic behavior and dye-sensitized solar cell (DSSC) performance were studied and compared with [111]-faceted anatase nanocrystals and anatase nanocrystals without a specific facet on the surface. There are two kinds of reactions in the formation process of the anatase nanocrystals. One is an in situ topochemical conversion reaction of layered titanate structure to anatase structure, and another is the dissolution–deposition reaction on the particle surface. The microwave hydrothermal process is suitable to control the structural conversion reaction for uniform the crystal size and morphology due to its uniform heating mechanism. The UV–visible spectrum results revealed that the bandgap of the TiO2 nanocrystals was enhanced in the order of nanocrystal without specific facet < [111]-faceted nanocrystal < {010}-faceted nanocrystal, which corresponded to their photocatalytic activities. The DSSC performance also was enhanced in the same order, suggesting that the {010}-faceted nanocrystals are promising for the high performance DSSCs.

V1-le vs. RVC-le in expressing resultant state in learners’ Mandarin interlanguage: evidence of two states of mind?

V1-le vs. RVC-le in expressing resultant state in learners’ Mandarin interlanguage: evidence of two states of mind?

Synthesis of {010}-faceted anatase TiO2nanoparticles from layered titanate for dye-sensitized solar cells

Crystal facets exposed on TiO2 nanoparticles strongly affect dye molecule adsorption and cell performance in dye-sensitized solar cells (DSSCs). In this study, size- and morphology-controllable {010}-faceted anatase-type TiO2 nanocrystals, including rhombic, tetragonal, and leaflike nanocrystals and platelike mesocrystals, were synthesized via hydrothermal treatment of layered titanate (HTO) nanosheet colloidal solutions. The formation reactions and nanostructures of the anatase nanocrystals were investigated using XRD, FE-SEM, and TEM. There are two kinds of reactions in the formation process of the anatase nanocrystals from the HTO nanosheets. One is an in situ topotactic structural transformation reaction and another is a dissolution–deposition reaction. The DSSC performance of the {010}-faceted anatase nanocrystals was investigated by measurements of I–V characteristics, electrochemical impedance spectra, and dye adsorptions and compared with [111]-faceted P25 nanocrystals and spherical ST20 nanocrystals without a specific facet on the surface. The DSSC results suggested that the Jsc and η values increase in the order of spherical nanocrystals without a specific facet < [111]-faceted nanocrystals < {010}-faceted nanocrystals, which concludes that the facet on the nanoparticle surface significantly impacts on the DSSC performance and the {010}-faceted nanocrystals are promising for the high-performance DSSCs.

Zeolites are no longer a challenge: Atomic resolution data by Aberration-corrected STEM

Transmission electron microscopy is undoubtedly an indispensable tool for materials characterization, which can currently reach sub-angstrom resolution down to the elemental building blocks of matter, isolated single atoms of most elements. In addition to the phenomenal image resolution, if the material is strong enough, it can be accompanied with chemical information, converting electron microscopy into a unique method for the analysis of a great variety of materials. Unfortunately, extracting all this valuable information is not simple as most materials in one way or another are affected by the strong and localized electron beam. Radiolysis is one kind of reaction between electrons and matter than can cause irreversible structural transformations in our materials. This effect is the predominant factor in zeolites, zeotypes and the majority of molecular sieves. In the present work some results, taken at high voltage (300kV) and minimizing the exposure to the beam, are presented proving the feasibility of the technique to obtain unprecedented atomic resolution information of different zeolites and microporous solids.

CeO2-based catalysts with engineered morphologies for soot oxidation to enhance soot-catalyst contact.

As morphology plays a relevant role in solid/solid catalysis, where the number of contact points is a critical feature in this kind of reaction, three different ceria morphologies have been investigated in this work as soot oxidation catalysts: ceria nanofibers, which can become organized as a catalytic network inside diesel particulate filter channels and thus trap soot particles at several contact points but have a very low specific surface area (4 m2/g); solution combustion synthesis ceria, which has an uncontrolled morphology but a specific surface area of 31 m2/g; and three-dimensional self-assembled (SA) ceria stars, which have both high specific surface area (105 m2/g) and a high availability of contact points. A high microporous volume of 0.03 cm3/g and a finer crystallite size compared to the other morphologies suggested that self-assembled stars could improve their redox cycling capability and their soot oxidation properties. In this comparison, self-assembled stars have shown the best tendency towards soot oxidation, and the temperature of non-catalytic soot oxidation has dropped from 614°C to 403°C in tight and to 552°C in loose contact conditions, respectively. As far as the loose contact results are concerned, this condition being the most realistic and hence the most significant, self-assembled stars have exhibited the lowest T10% onset temperature of this trio (even after ageing), thus proving their higher intrinsic activity. Furthermore, the three-dimensional shape of self-assembled stars may involve more of the soot cake layer than the solution combustion synthesis or nanofibers of ceria and thus enhance the total number of contact points. The results obtained through this work have encouraged our efforts to understand soot oxidation and to transpose these results to real diesel particulate filters.

RADIATION EFFECTS ON HEAT AND MASS TRANSFER OF A MHD NANO FLUID

The significant research saw with nano fluid flow and heat transfer. But, there was a wide scope of research in mass transfer with nano fluids, due to Brownian motion of particles. A theoretical investigation attempted in this paper to study the chemical reaction effects during mass transfer. We studied convective heat and mass transfer of MHD nano fluid flow past inclined, oscillating permeable flat plate with radiation and heat source. It is found that velocity and Diffusion increases for both kinds of chemical reactions.

Photodegradation of several triazidic and organophosphorus pesticides in water by pulsed light technology

Abstract Pulsed light technology consists of a successive repetition of short duration (325 μs) and high power flashes emitted by xenon lamps. These flashlamps radiate a broadband emission light (approximately 200–1000 nm) with a considerable amount of light in the short-wave UV spectrum. In the present work, this technology was tested as a new tool for the degradation of several herbicides in water: simazine, atrazine, phosmet, azinphos-methyl, methyl-parathion, pirimiphos-methyl and chlorpyrifos-ethyl. To evaluate the presence and evolution with time of these herbicides, as well as the formation of derivatives, liquid chromatography–mass spectrometry (atmospheric pressure chemical ionization) ion trap operating in positive mode was used. The degradation process followed first-order kinetics for all studied compounds except for parathion. Fluences about 4.65 J/cm 2 induced 50% reduction of simazine, atrazine, phosmet, azinphos-ethyl and pirimiphos-ethyl, independently of these compounds were PL treated separately or mixed in an aqueous solution. A higher fluence (9.81 J/cm 2 ) was needed to induce 50% reduction for chlorpyrifos-ethyl, being more difficult to degrade it in presence of other pesticides in the same solution. While simazine and atrazine were degraded, no chlorinated photoproducts were formed. Partial dechlorination was also observed for chlorpyrifos-ethyl. For the rest of organophosphorus pesticides different kinds of reactions could be suggested such as oxidative desulfuration, oxidation of ethyl groups or N-dealkylations. The molecular structures for some of derivatives could be proposed. The different formation profiles of photoproducts suggested that the degradation pathway may include several successive and competitive steps, with subsequent degradation processes taking part from the already formed degradation products. According to the degradation efficiency, the short treatment time and the type of derivatives, this new technology could be considered as an alternative for water treatment.

Leadership and International Climate Cooperation

Which kind of reaction can a nation or group of nations expect when leading by example in climate policy? This literature survey describes possible positive reaction mechanisms from different fields of economics, some of which have scarcely been linked to climate economics previously. One effect may be behavioral, a reaction motivated by fairness, reciprocity or norms. Second, other nations may interpret the leader's action as a signal on his preference or the value of the objective and adjust their own policy based on the new information. Third, the leader may provide a service to other nations, which decreases their costs and risks. The followers could benefit by learning successful policies, adopting technologies and obtaining information on the cost of environmental policy. In addition to these economic mechanisms, a leading group of nations might initiate a political process of successive enlargements.

Intracellular lectins are involved in quality control of glycoproteins

Glycoprotein quality control is categorized into three kinds of reactions; the folding of nascent glycoproteins, ER-associated degradation of misfolded or unassembled glycoproteins, and transport and sorting of correctly folded glycoproteins. In all three processes, N-glycans on the glycoproteins are used as tags that are recognized by intracellular lectins. We analyzed the functions of these intracellular lectins and their sugar-binding specificities. The results clearly showed that the A, B, and C-arms of high mannose-type glycans participate in the folding, transport and sorting, and degradation, respectively, of newly synthesized peptides. After correctly folded glycoproteins are transported to the Golgi apparatus, N-glycans are trimmed into Man3GlcNAc2 and then rebuilt into various complex-type glycans in the Golgi, resulting in the addition of diverse sugar structures that allow glycoproteins to play various roles outside of the cells.

From reaction to initiative: Potentials of contributive participation

Participation in spatial planning has been studied exten‐ sively in the past decades, but many cases of spatial plan‐ ning have nonetheless seen a gap between decision‐mak‐ ers and local residents. This is why participation in spatial planning has become a classic research question of many urban planning–related sciences. The greatest focus has been on cases of participation that present some kind of reaction to plans or actions, whereas far less attention has been given to cases of participation based on initiatives and the search for new content for underused or decay‐ ing areas. Such cases usually start with initiatives for the new use of particular places and often result in physical changes to these places. This article defines various types of local initiatives, and it especially studies the distinction between reactionary and contributive local initiatives and relates them to the notion of community. The article is based on an analysis of two particular cases. The differ‐ ences in these two cases represent a foundation for the article’s conclusions, which emphasises the potentials for stimulating contributive participation. The conclusion in‐ cludes recommendations for the spatial planning system to become more open to participation in terms of revi‐ talising underused spaces because such space has been increasing during the economic downturn. The complex and inefficient system of spatial planning is turning away many creative initiatives.

Hemisynthesis and Structural and Chromatic Characterization of Delphinidin 3-O-Glucoside–Vescalagin Hybrid Pigments

During red wine maturation in the presence of oak wood, reactions involving anthocyanins and ellagitannins might affect wine organoleptic properties such as color and astringency. In this work, the condensation reaction between myrtillin (delphinidin 3-O-glucoside) and vescalagin has been performed to determine the behavior of this anthocyanin in this kind of reaction and to assess the possible impact of such a reaction in wine color modulation. Two different hybrid pigments have been hemisynthetized and characterized by HPLC-DAD-MS and NMR spectroscopy. These pigments have been identified as 1-deoxyvescalagin-(1β→8)-myrtillin (major) and 1-deoxyvescalagin-(1β→6)-myrtillin (minor). The minor pigment could be formed both by the condensation reaction and by a regioisomerization process from the major pigment. Moreover, the chromatic properties of these pigments have been studied and compared to those of myrtillin. The hybrid pigments showed an important bathochromic shift (ca. 20 nm) in the maximum absorbance wavelength and lower molar absorption coefficients.

Simultaneous estimation of kinetics and catalysts activity during cracking of 1,3,5-tri-isopropyl benzene on FCC catalyst

Catalytic cracking reactions, performed on commercial catalysts, are difficult to follow because of the simultaneous deactivation of the catalyst as consequence of coke deposition on catalyst surfaces during cracking of hydrocarbon molecules. In this work, a model for catalyst deactivation in terms of fouling because of blockage of micropores of the catalyst is used to estimate activity independently of reaction rates; later cracking kinetic rates of a model compound are estimated. It was found that the expected low energy of coke deposition reactions dominate the process, however these reactions are not easy to estimate a priori because of the definition of coke as a lumped entity. A comprehensive model of a CREC-Riser simulator Reactor is developed in order to consider mass balances for each specific operating condition. Three temperatures and two contact times are used to evaluate frequency factors and activation energies of the reactions that take place during the catalytic cracking of 1,3,5-tri-isopropyl benzene in two cases, with catalyst coming from an industrial unit and with catalyst pre-coked in laboratory. A methodology to separate activity and apparent kinetics in this kind of reactions is proposed.

Editorial Comment

Mental and emotional stress induced by external or internal stressors, or both, can exert biological effects. Some stress, such as when it is a temporary and acute reaction danger or a problem, is positive. Biological effects in this scenario would enhance one's ability to handle or avert the stressor. Continuous or chronic stress, however, is a negative reaction that may contribute variably and adversely to health. Chronic stress in susceptible individuals may contribute to, worsen, or even cause some conditions, including altered blood pressure, compromised immune status, headaches, cardiovascular problems, aberrant insulin metabolism, worsening of asthma, back pain, and arthritis, gastrointestinal problems, and mood and behavior changes. 1 Russell E. Koren G. Rieder M. et al. Hair cortisol as a biological marker of chronic stress: current status, future directions and unanswered questions. Psychoneuroendocrinology. 2012; 37: 589-601 Abstract Full Text Full Text PDF PubMed Scopus (595) Google Scholar A role for stress in cancer metastasis is proposed. 2 Moreno-Smith M. Lutgendorf S.K. Sood A.K. Impact of stress on cancer metastasis. Future Oncol. 2010; 6: 1863-1881 Crossref PubMed Scopus (269) Google Scholar In certain individuals, stress reduction appears to attenuate disease effects or decrease disease progression. 3 Schneider R.H. Grim C.E. Rainforth M.V. et al. Stress reduction in the secondary prevention of cardiovascular disease: randomized, controlled trial of transcendental meditation and health education in Blacks. Circ Cardiovasc Qual Outcomes. 2012; 5: 750-758 Crossref PubMed Scopus (133) Google Scholar , 4 Baker J. Costa D. Nygaard I. Mindfulness-based stress reduction for treatment of urinary urge incontinence: a pilot study. Female Pelvic Med Reconstr Surg. 2012; 18: 46-49 Crossref PubMed Scopus (18) Google Scholar But does this relationship extend to kidney stone formation or to unusually aggressive or more complex stone problems? Chronic Stress and Calcium Oxalate Stone Disease: Influence on Blood Cortisol and Urine CompositionUrologyVol. 82Issue 6PreviewTo evaluate the influence of chronic stress (CS) on urine composition of calcium oxalate (CaOx) stone patients and controls. Full-Text PDF ReplyUrologyVol. 82Issue 6PreviewThe Editorial Comment provides an excellent summary of our current knowledge of the relation between stress and disease. That some acute stress reactions are necessary to protect us in dangerous situations is well known. However, when this kind of reaction is maintained continuously over a long period, it can become a risk factor for a variety of chronic illnesses. The objective of our study was to examine a possible link between chronic stress, measured from a multidimensional point of view, with one specific chronic illness: calcium oxalate (CaOx) stone disease. Full-Text PDF