Physical Chemistry

The characterization of novel metal reinforced electro-dialysis ion exchange membranes, for water desalination, by attenuated total reflectance Fourier Transform infra-red spectroscopy mapping is presented in this paper. The surface of the porous stainless steel fibre meshes was treated in order to enhance the amount of surface oxide groups and increase the material hydrophilicity. Then, the metal membranes were functionalized through a sol-gel reaction with silane coupling agents to enhance the affinity with the ion exchange resins and avoid premature metal oxidation due to redox reactions at the metalpolymer interface. Polished cross sections of the composite membranes embedded into an epoxy resin revealed interfaces between metallic frameworks and the silane layer at the interface with the ion exchange material. The morphology of the metalpolymer interface was investigated with scanning electron microscopy and Fourier transform infra-red micro-spectroscopy. Fourier transform infra-red mapping of the interfaces was performed using the attenuated total reflectance mode on the polished cross-sections at the Australian Synchrotron. The nature of the interface between the metal framework and the ion exchange resin was shown to be homogeneous and the coating thickness was found to be around 1 μm determined by Fourier transform infra-red micro-spectroscopy mapping. The impact of the coating on the properties of the membranes and their potential for water desalination by electro-dialysis are also discussed.

Two-dimensional layered transition-metal dichalcogenides (2D-TMDs) have garnered significant attention due to their layer number-dependent electronic properties, making them promising candidates for atomically thin electronics and optoelectronics. However, current research has primarily focused on exfoliated TMD materials, which have limitations in size, layer number control, and yield. Therefore, a crucial challenge remains in producing large single TMD crystals with precise control over the layer number. A comprehensive understanding and precise control of the growth conditions are imperative to address this challenge. This study systematically investigated key growth conditions, including temperature, precursor flow, growth duration, material quantity, gas flow, and slide position. By optimizing these parameters, we successfully synthesized TMD materials with an impressive size of 850 µm. Notably, we achieved the preparation of monolayer WS2 single crystals on a large scale withi...

Chronic positive energy balance has surged among societies worldwide due to increasing dietary energy intake and decreasing physical activity, a phenomenon called the energy balance transition. Here, we investigate the effects of this transition on bone mass and strength. We focus on the Indigenous peoples of New Mexico in the United States, a rare case of a group for which data can be compared between individuals living before and after the start of the transition. We show that since the transition began, bone strength in the leg has markedly decreased, even though bone mass has apparently increased. Decreased bone strength, coupled with a high prevalence of obesity, has resulted in many people today having weaker bones that must sustain excessively heavy loads, potentially heightening their risk of a bone fracture. These findings may provide insight into more widespread upward trends in bone fragility and fracture risk among societies undergoing the energy balance transition.

Understanding the relationship between the active material's structure and function in operational devices is key for the rational engineering of the next generation of devices. However, this has proven elusive due to the invasiveness of structural characterization methods and their inability to 20 penetrate the multi-layered device. Here, we introduce a Correlation Clustering Imaging Method (CLIM) based on photoluminescence microscopy. CLIM offers insights into structural and functional aspects related to carrier transport, defects, and recombination losses in operational photovoltaic devices. Our study reveals the presence of "blinking" phenomena in high-quality semiconductor films and their corresponding devices. CLIM demonstrates that highly correlated 25 clusters correspond precisely to grain structures of perovskite layer on glass observed with SEM. Importantly, we find that the perovskite layer in photovoltaic devices exhibits predominant blinking during specific operational conditions. The correlated regions within devices are notably larger than those on bare substrate, indicating different microstructures likely caused by the transport layer at the interface. CLIM's contrast opens new possibilities in optical microscopy for 30 functional imaging of materials and in-operando device, enabling the rational design and optimization of high-efficiency photovoltaic devices.

Photoluminescence of CH 3 NH 3 PbI 3 perovskite depends strongly on sample preparation, atmosphere, crystal size, etc. However, the origin of these dependencies is always misunderstood due to the co-works of many different factors. Herein, we prepared hexagonal-shaped single crystals with tens of micrometers in size and observed a red-shifted PL emission (800 -830 nm) mainly from the crystal edges besides the usual band-to-band transition (760 nm) from the central regions. Also, significantly different time-resolved dynamics and excitation power dependencies were observed. To summary, we conclude that the red-shifted component comes from the depth of the crystal where monomolecular recombination occurs involving photogenerated charges and unintentional doped charges, while the normal PL is emitted by bimolecular recombination from the surface layers. These results showed the significance of pure optical effects in perovskite crystals and would promote detailed understanding of the charge dynamics and recombination in perovskite crystalline materials of different geometries and sizes.

Organo metal halide perovskites are solution processed semiconductors that recently attracted a great attention. They possess a rather "soft" and (photo) chemically active solid structure allowing for ion migration and other mass diffusion processes. This is a likely reason why non-radiative recombination centres in these materials are activated and deactivated on relatively slow time-scales. This dynamics reveals as photoluminescence (PL) fluctuations (blinking) of individual microcrystals and local areas of films and allows for application of a broad range of single molecule spectroscopy methods including optical super-resolution. Studying PL blinking resolves properties of individual non-radiative centres and helps to unravel their chemical nature.

Organo metal halide perovskites are solution processed semiconductors that recently attracted a great attention. They possess a rather “soft” and (photo) chemically active solid structure allowing for ion migration and other mass diffusion processes. This is a likely reason why non-radiative recombination centres in these materials are activated and deactivated on relatively slow time-scales. This dynamics reveals as photoluminescence (PL) fluctuations (blinking) of individual microcrystals and local areas of films and allows for application of a broad range of single molecule spectroscopy methods including optical super-resolution. Studying PL blinking resolves properties of individual non-radiative centres and helps to unravel their chemical nature.

A series of mononuclear lanthanide-based coordination compounds was obtained under mild synthetic conditions and fully characterized. Single-crystal X-ray diffraction reveals six isomorphic compounds of type [Ln(NO3)(4picH)2(H2O)4](NO3)2 (Ln3+ = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6)), in which 4picH is the zwitterionic form of the 4-picolinic acid. Except for compounds 3 and 6, a study into the emissive properties of the compounds was carried out, revealing a ligand-sensitized lanthanide-characteristic luminescence. Compounds 2 and 4 are candidates for luminescent probes in solution. At the same time, the chromaticity data for 5 revealed a potential white-light emitter with a correlated color temperature (CCT) value of 6570 K. Alternating current (AC) magnetic susceptibility measurements, supported by theoretical calculations, showed a field-induced slow relaxation of the magnetization and a single-ion magnet behavior for compound 5.

Nanotechnology deals with the construction of new materials, devices, and different technological systems with a wide range of potential applications at the atomic and molecular level. Nanomaterials have attracted great attention for numerous applications in chemical, biological, and industrial world because of their fascinating physicochemical properties. Nanomaterials and nanodevices are being produced intentionally, unintentionally, and manufactured or engineered by different methods and released into the environment without any safety test. Nantoxicity has become the subject of concern in nanoscience and nanotechnology because of the increasing toxic effects of nanomaterials on the living organisms. Nanomaterials can move freely as compared to the large-sized particles; therefore, they can be more toxic than bulky materials. This review article delineates the toxic effects of different types of nanomaterials on the living organisms through different sources, like water, air, con...

I would like to thank all my colleagues at Novo Nordisk A/S for all their social and academic input, and my six supervisors for their invaluable critics and guidance throughout the project. I have particularly had great benefit of my two main supervisors, Principal Scientist Lasse W. Christoffersen and Prof. Martin E. Vigild, who I have learned immensely from. I acknowledge funding from the Danish Ministry of Science, Technology and Innovation, VTU, and the department of Corporate Research Affairs at NNAS. Moreover, I owe special thanks to my manager at NNAS, Director of Materials & Device Characterisation Niels Bjerrum Thomsen, PhD, for his kind engagement in my project and my further education. Special thanks are also due to laboratory technician Charlotte Anker for her help with various experimental characterisations, which has been beyond reasonable limits.

The pathogenesis of multiple sclerosis (MS) is unknown. Searching for possible toxic factors, it was found that 3-day exposure to heat-treated cerebrospinal fluid (CSF) from MS patients caused apoptotic death of astrocytes and oligodendrocytes, but not fibroblasts, myoblasts, Schwann cells, endothelial cells and neurons, in vitro. CSFs from other inflammatory or non-inflammatory neurological diseases showed no toxicity. Exposure of these glial cells to partially purified MS CSF produced DNA fragmentation, apoptotic bodies, chromatin condensation, cell shrinkage, and changes in the levels of known cytokines. A cytotoxic factor, called gliotoxin, was characterized chromatographically as a stable 17-kDa glycoprotein. Since this protein is highly cytotoxic for astrocytes and oligodendrocytes, it may represent an initial pathogenic factor, leading to the neuropathological features of MS, such as blood-brain barrier involvement and demyelination.

Knowledge of chemical mobility of heavy metals is fundamental to understanding their toxicity, bioavailability, and geochemical behavior. In this paper, two different methods, i.e. mineralogical means and sequential extractions, were employed to analyze the total contents, existing states, and chemical forms of heavy metals in coal mine spoils. The results demonstrate that the mobility of heavy metals in coal mine spoils depends not only on their existing states and the stability of their host minerals but also on the properties of the coal mine spoils. In the process of coal mine spoils-water interaction, sulfides that contain heavy metals first break down and release metals, which are then adsorbed and complexed by the iron oxyhydroxide colloid resulting from pyrite oxidization and organic matter. During the natural weathering of coal mine spoils, only a small fraction of these metals are released to the environment, and most of them still remains in the residual material # 2002 Elsevier Science Ltd. All rights reserved.

In the temperature range (80-250) 0 С, the frequency dependence of the admittance of thin (90 nm) AgI films with a semiconductor-superionic phase transition has been studied. The applicability of the Debye theory for modeling the physical mechanism of the dielectric response of a material to the action of an alternating electric field is shown. It has been found that the reported experimental technique makes it possible to separately determine the parameters of the electronic and ionic components of the electrical conductivity of a superionic.

Selective determination of caffeic acid, was carried out by using Screen Printed Carbon Electrode (SPCE) to give a reliable, scalable, and inexpensive electrochemical method with enhanced analytical performance. SPCE was first activated by linear sweep voltammetry using KOH solution, followed by its electrochemical grafting with cyclodextrins. Britton Robinson buffer (BRB) solution having pH 8.1, demonstrated a clear electrocatalytic impact towards caffeic acid oxidation, which indicated a greater current response compared to the activated electrode in the cyclic voltammetric and square wave voltammetric (SWV) investigations. The SWV waves at the activated SPCE was used under ideal conditions to produce a linear calibration curve with detection limits of (LoD, 4 sb/m) and quantification limits of (LoQ, 11 sb/m) of 0.38 mM and 1.1 M, respectively.

Fossil fuels, currently the leading source of energy, subsidize a lot of CO 2 to the environment, causing many environmental issues including the greenhouse effect. To address these challenges, there is a need to develop alternative and renewable energy resources for a sustainable future. Water, being a renewable source, is a promising candidate because of its ability to produce H 2 (HER-cathodic reaction) and O 2 (OERanodic reaction) by providing electricity. However, the overall efficiency of water splitting is limited due to the high overpotential for half-cell anodic reaction, thus becoming a hot area of research to beat its sluggish thermodynamics and slow kinetics. Molecular nanoclusters (MNCs) are emerging materials because of their unique optical, catalytic, magnetic, and electronic properties. These unique properties are due to various factors including electronic shell closing (Jellium model), geometric shell closing, high surface-to-volume ratio, and super atomic behavior, unlike their bulk counterparts. This chapter will summarize the well-developed research information on MNCs and their potential for OER. It will create a link between the reported and ongoing work, consequently helping the researchers to identify future research directions in nanocatalysis for making the water-splitting process an economically viable process for H 2 production.

The behavior of Langmuir monolayers of methyl octadecanoate, methyl nonadecanoate, and methyl eicosanoate has been studied by polarized fluorescence microscopy and Brewster angle microscopy in the neighborhood of a transition between two liquid-condensed (LC) phases. As the monolayer is cooled through the transition, the

Threshold Photoelectron-Photoion Coincidence Spectroscopy (TPEPICO) has been used to study the ionic dissociation dynamics and energetics of Me 6 Ge 2 (Me = CH 3 ). Ions are energy-selected and the 0 K dissociation onsets for methyl and Me 3 Ge • loss are obtained from the breakdown diagram and mass spectra distributions, both of them analyzed and modeled with statistical SSACM theory and quantum chemical (DFT, MP2) calculations. An updated value for the enthalpy of formation, .8  8.9 kJmol -1 . The bond dissociation enthalpies, BDE (GeX), of Me 3 Ge-X (X = Me, GeMe 3 , Cl and Br) were also derived in this study.

This chapter examines symmetries in the physical universe from the perspective of a geometry based on spheres of 4D space with a diameter equal to the Planck length. Through these spheres, a connection is proposed between the fundamental properties of particles and the fields they generate, highlighting that the properties of mass, energy, momentum and electric charge emerge as manifestations of the rotation and curvature of space.
The implications of these symmetries in the context of quantum mechanics and relativity are also reviewed, considering the possibility of unifying concepts in a deeper geometric framework. The exploration of these ideas could offer new perspectives on the nature of mass, energy and the fundamental interaction between particles.

Recently, niobium-based oxides have attracted increasing interest as a potential choice for lithium-ion battery technology. The mixed oxide of niobium and titanium, in the composition of TiNb2O7, has been considered a promising candidate for the anodic materials of new generation lithium-ion batteries. However, its precursors require a severe and costly purification process since they are processed from complex ores. In addition to the purification cost, these steps result in significant amounts of acid and alkaline effluents, which generate additional costs for their treatment. The present research was designed to understand the influence of contaminants commonly found in ores or inserted in the process routes to obtain niobium oxides. Iron, potassium, phosphorus, tantalum, and fluoride were inserted into the TiNb2O7 synthesis process from ultrapure solutions. The mixed oxides obtained were subjected to characterizations by the X-ray diffraction technique, scanning electron microsc...

Four-stranded nucleic acid structures are central to many processes in biology and in supramolecular chemistry. It has been shown recently that four-stranded DNA structures are not only limited to the classical guanine quadruplex but also can be formed by tetrads resulting from the association of Watson-Crick base pairs. Such an association may occur through the minor or the major groove side of the base pairs. Structures stabilized by minor groove tetrads present distinctive features, clearly different from the canonical guanine quadruplex, making these quadruplexes a unique structural motif. Within our efforts to study the sequence requirements for the formation of this unusual DNA motif, we have determined the solution structure of the cyclic oligonucleotide d〈pCCGTCCGT〉 by two-dimensional NMR spectroscopy and restrained molecular dynamics. This molecule self-associates, forming a symmetric dimer stabilized by two G:C:G:C tetrads with intermolecular G-C base pairs. Interestingly, although the overall threedimensional structure is similar to that found in other cyclic and linear oligonucleotides of related sequences, the tetrads that stabilize the structure of d〈pCCGTCCGT〉 are different to other minor groove G:C:G:C tetrads found earlier. Whereas in previous cases the G-C base pairs aligned directly, in this new tetrad the relative position of the two base pairs is slipped along the axis defined by the base pairs. This is the first time that a quadruplex structure entirely stabilized by slipped minor groove G:C:G:C tetrads is observed in solution or in the solid state. However, an analogous arrangement of G-C base pairs occurs between the terminal residues of contiguous duplexes in some DNA crystals. This structural polymorphism between minor groove GC tetrads may be important in stabilization of higher order DNA structures.

Covalently linked peptide ± oligonucleotide hybrids were used as models for studying tryptophan ± DNA interactions. The structure and stability of several hybrids in which peptides and oligonucleotides are linked through a phosphodiester bond between the hydroxy group of a homoserine (Hse) side chain and the 3'-end of the oligonucleotide, have been studied by both NMR and CD spectroscopy and by restrained molecular dynamics methods. The three-dimensional solution structure of the complex between Ac-Lys-Trp-Lys-Hse(p3'dGCATCG)-Ala-OH (p phosphate, Ac acetyl) and its complementary strand 5'dCGTAGC has been determined from a set of 276 experimental NOE distances and 33 dihedral angle constraints. The oligonucleotide structure is a well-defined duplex that belongs to the B-form family of DNA structures. The covalently linked peptide adopts a folded structure in which the tryptophan side chain stacks against the 3'-terminal guanine moiety, which forms a cap at the end of the duplex. This stacking interaction, which resembles other tryptophan ± nucleobase interactions observed in some protein ± DNA complexes, is not observed in the single-stranded form of Ac-Lys-Trp-Lys-Hse(p3'dGCATCG)-Ala-OH, where the peptide chain is completely disordered. A comparison with the pure DNA duplex, d(5'GCTACG3') ± (5'CGTAGC3'), indicates that the interaction between the peptide and the DNA contributes to the stability of the nucleopeptide duplex. The different contributions that stabilize this complex have been evaluated by studying other nucleopeptide compounds with related sequences.

Changes in total protein and protein fractions were investigated during fermentation and/or cooking after supplementation of sorghum flour with defatted groundnut flour were investigated. The protein content and fractions were significantly (p ≥ 0.05) increased after supplementation with defatted groundnut flour. The albumin plus globulin fraction increased significantly (p ≥ 0.05) during the first 8h of fermentation after supplementation with 20% groundnut flour. Other fraction contents were observed to fluctuate during the fermentation time. Supplementation of the cultivar flour with 20% groundnut flour greatly increased the protein content as well as the albumin plus globulin fraction while other fractions were significantly decreased. Sensory evaluation of locally processed sorghum products (Kisra, Asida and Nasha) before and after supplementation showed no difference between the supplemented samples and the control ones as judged by trained panellists.

Adsorption of environmentally important aromatic molecules on a water surface is studied by means of classical and ab initio molecular dynamics simulations and by reflectionabsorption infrared spectroscopy. Both techniques show strong activity and orientational preference of these molecules at the surface. Benzene and naphtalene, which bind weakly to water surface with a significant contribution of dispersion interactions, prefer to lie flat on water but retain a large degree of orientational flexibility. Pyridine is more rigid at the surface. It is tilted with the nitrogen end having strong hydrogen bonding interactions with water molecules. The degree of adsorption and orientation of aromatic molecules on aqueous droplets has atmospheric implications for heterogenous ozonolysis, for which the Langmuir-Hinshelwood kinetics mechanism is validated. At higher coverages of aromatic molecules the incoming ozone almost does not come into contact with the underlying aqueous phase. This may rationalize the experimental insensitivity of the ozonolysis on the chemical nature of the substrate on which the aromatic molecules adsorb.

A new model for analyzing in situ small-angle X-ray scattering measurements of the formation of hexagonal ordered mesoporous silica has been developed. It employs a factorization of the scattering intensity into contributions from the form factor and the structure factor. The model can therefore be used for the entire synthesis from the first aggregation between the silica and surfactant to the formation of the final wellordered material. It is shown that the model describes very well the experimental data from a synthesis of a material similar to SBA-15 where a nonionic surfactant is used as a structural directing agent for making mesoporous silica. The actual synthesis has been developed recently, and the main difference, as compared to the SBA-15 synthesis, is the synthesis pH of 2-3. This gives a comparably slow reaction rate and therefore better temporal resolution of the changes during the synthesis. The combination of the advanced model and the relatively slow synthesis means that the synthesis can be followed in greater detail than reported before. The results illustrate that the silica and the poly(ethylene oxide) (PEO) of the Pluronic interact at an early stage, forming cylindrical micelles. The increase in concentration of silica in the PEO region of the micelles can be followed, and it is determined how this affects the radii of both the core and the corona. The interaction then leads to the formation of larger aggregates of cylinders, and at this stage the hexagonal order also appears. The degree of order in the material can be followed in detail with the model, and it is shown that it increases rather slowly with time.

ZSM-5 zeolite was synthesized by sourcing silica from wheat husk ash and was converted into its protonated form following careful, conventionally accepted ion-exchange method and calcinations. The H-ZSM-5 zeolite (Si/Al ratio = 30) prepared was appropriately characterized by XRD, FT-IR, SEM, TEM, TG-DTA, CV, and so forth, and evaluated as recyclable catalyst in selective organic transformations including three- and four-component reactions. The catalytic activity of the zeolite sample supposedly relates to increased density of the accessible acid sites.

Oxide films produced from plasma electrolytic oxidation are porous in structure. While they have some passivating effect in Mg alloys, the pores still lead to corrosion over long periods of exposure. In this study, spray pyrolysis was used to seal the porous oxide layer developed through the plasma electrolytic oxidation method on Mg alloy AZ31. The PEO coating acted as a good base for the application of spray pyrolysis due to its morphology. Three different kinds of coatings were obtained using different precursors: zinc acetate for ZnO, phosphoric acid for phosphate (P), and a mixture of zinc acetate and sodium phosphate for ZnO+P. The corrosion performance of all three coatings was studied by performing electrochemical impedance and polarization tests on the samples. Mass loss over a duration of 1 week was measured in 3% NaCl solution using immersion gravimetry. The coating with only phosphate (P) was found to be most corrosion-resistant with 52 times lower rate of corrosion and ...

Hydrophilic carotenoids, unusual members of an intrinsically hydrophobic family, and their radical ions are important reactants. An all-optical method for generating singly charged radical ions of a hydrophilic carotenoid (Car) is described. It relies on photolyzing an aqueous mixture of Car and a photoionizable auxiliary solute (A), and making conditions conducive to the capture, by Car, of the hydrated electron (e À aq ) or the positive hole in A + or both. When A is Trolox (TOH), only e À aq can be captured, since TOH + deprotonates too rapidly to be a hole donor; when A is Trolox methyl ether (TOMe), both Car À and Car + are formed, since TOMe + lives long enough to transfer its positive hole to Car; formation of Car À is prevented under aerobic conditions.

In the automotive production line, a single pair of electrodes is employed to produce hundreds of consecutive welds before undergoing dressing or replacement. In consecutive resistance spot welding (RSW) involving Zn-coated steels, the electrodes undergo metallurgical degradation, characterized by Cu-Zn alloying, which impacts the susceptibility to liquid metal embrittlement (LME) cracking. In the present investigation, the possibility of LME crack formation in uncoated TRIP steel joints during consecutive RSW (involving 400 welds in galvannealed and uncoated TRIP steels) was investigated. The results have shown that different Cu-Zn phases were formed on the electrode surface because of its contamination with Zn from the galvannealed coating. Therefore, during the welding of the uncoated TRIP steel, the heat generated at the electrode/sheet interface would result in the melting of the Cu-Zn phases, thereby exposing the uncoated steel surface to molten Zn and Cu, leading to LME crack...

from considering the asymmetry of the molecule and the presence of three chiral centers. However, for a particular methylene segment, not all chiral centers are effective to produce inequivalence of the two deuterons. We have found that the molecular packing of AOT in surfactant layers is similar to what is found in phospholipid bilayers-with a preferred bending of one of the chains close to the headgroup Acknowledgment. We are grateful to HAkan Wennerstrom for clarifying discussions and to Erick J. Duforc for allowing us to use his computer simulation program. T.C.W. thanks the University of Missouri for granting a research leave. This work was supported by the Swedish Natural Science Research Council. Registry No. AOT, 127399-06-8. -. region. This particular packing of AOT and phospholipids is due to the asymmetry of the molecules. It is interesting to note that, in the case of AOT? this particular packing is found not only in a bilayer (the lamellar phase) but also in a monolayer where the mean curvature of the polar-apolar interface is toward the polar solvent (the reversed hexagonal phase). We note, finally, that the system AOT-H20, strictly speaking, should be recognized as a nine-component system. Stereoisomers

It is now widely accepted that nanometer sized bubbles, attached at a hydrophobic silica surface, can cause rupture of aqueous wetting films due to the so-called nucleation mechanism. But, the knowledge of the existence of such nano-bubbles doesn't give an answer how the sub-processes of this rupture mechanism operate.

The conformation and dynamics of a DNA oligomer, d[(CG)3TATA(CG)3], in 4M NaC104 (Z- TATA 16 mer) have been studied by IH NMR. The principal results of our investigation are: (i) at low temperature d[(CG)3TATA(CG)3] exists as duplexes in both low (0. 1M NaCI) and high (4M NaCl04) ionic strength solutions; (ii) CGCGCG segments undergo the B-to-Z transition in 4M NaCl04; (iii) even in 4M NaCl04 the TATA box exhibits non-Z-structures and possesses multiple conformations which are slowly exchanging on the NMR chemical shift difference time scale; and, (iv) the Z-type structure of the CGCGCG segments induced in 4M NaCI04 is more conformationally mobile than its B-type counterpart in 0. IM NaCl on the nanosecond time scale.

The effort to drive solution-based perovskite solar cells towards higher efficiency has been considerable, reaching over 24%. Such progress has been made possible by the low-energy barrier to crystallization. The low-energy barrier in the reverse direction, however, also renders them susceptible to dissociation from heat, moisture, and photoexcitation. Consequently, studies that provide information on the stability of perovskites are of considerable importance. It has been reported that perovskite crystals formed using different stoichiometries of the organic precursors and metal halide are equivalent. Our findings, however, suggest that the difference in reaction pathways affects the quality of the final crystal and that changes in morphology and the production of any defects can lead to differences in behavior under illumination. Here, we present photoluminescence spectra subsequent to nanosecond photoexcitation of perovskites synthesized under various conditions. Our results indicate that the presence of excess precursors (i.e., CH3NH3X, X= I and surfactant) gives rise to an ~20-nanosecond relaxation time with which the photoluminescence spectrum achieves its equilibrium value. This relaxation is absent in bulk, polycrystalline material. This is, to our knowledge, the first report of the ~20-ns relaxation time, which we attribute to cation migration. These structural changes are not detectable subsequent to photoexcitation by x-ray diffraction, nor are they detectable by in situ x-ray diffraction during photoexcitation.

Novel modification of ethylene-vinyl alcohol copolymers were carried out. The modifications of series of the copolymers were carried out by reacting them with chloroacetyle chloride followed by amination with ethylene diamine which used for many applications, such as water sterilization, drugs, soil sterilization, biomedical-device sterilization, and prevention of the microbial contamination of shipboard, water compensated, and hydration fuel tanks. The structure of the resulting materials was characterized with Fourier transform infrared-spectroscopy, TGA analysis and elemental analysis. The antimicrobial activity of the polymers against variety of test microorganisms was examined by the cut plug and viable cell counting methods. It was found that the immobilized polymers exhibited antimicrobial activity against the Gram negative bacteria (Escherichia coli ATCC 8739), Gram-positive bacteria (Staphylococcus aureus ATCC 6633), fungi (Candida albicans and Aspergillus niger. The growth inhibition of the test microorganisms (ratio of surviving cell number, M/C) varied according to the composition of the active group in the polymer and the test organism. It increased by increasing the concentration of the modified copolymers.

Corrosion damage to metal materials is often related not only to metal loss but also to the decommissioning of components from the installations, the replacement and installation of which costs about 3% per year of the cost of the material from which they are made. The effects of galvanic corrosion on the operation of plants and equipment can be anticipated, observed and controlled. Following an economic analysis and the works to be carried out, a balance can be struck between the impact of corrosion of the mechanical elements in the chrome plating bath and the costs for its prevention. The prevention of corrosion at the design stage can lead to lower annual corrosion-related costs, which are much lower than the costs of remedying the causes when the construction of equipment and plants has already been completed. The aim of this study is based on an analysis of the effect of electrochemical processes in the chromium plating solution on the copper anode bar in continuous chromium plating plants. Initially the forms of corrosion damage to the metal material were identified and then attempts were made to develop methods to reduce and avoid their destruction.

Interactions of polycationic polymers with supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayers and live cell membranes (KB and Rat2) have been investigated using atomic force microscopy (AFM), cytosolic enzyme assays, confocal laser scanning microscopy (CLSM), and a fluorescence-activated cell sorter (FACS). Polycationic polymers poly-L-lysine (PLL), polyethylenimine (PEI), and diethylaminoethyl-dextran (DEAE-DEX) and sphere-like poly(amidoamine) (PAMAM) dendrimers are employed because of their importance for gene and drug delivery. AFM studies indicate that all the polycationic polymers cause the formation and/or expansion of preexisting defects in supported DMPC bilayers in the concentration range of 1-3 µg/mL. By way of contrast, hydroxyl-containing neutral linear poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA) do not induce hole formation or expand the size of preexisting defects in the same concentration range. All polymers tested are not toxic to KB or Rat2 cells up to a 12 µg/mL concentration (XTT assay). In the concentration range of 6-12 µg/mL, however, significant amounts of the cytosolic enzymes lactate dehydrogenase (LDH) and luciferase (LUC) are released. PEI, which possesses the greatest density of charged groups on its chain, shows the most dramatic increase in membrane permeability. In addition, treatment with polycationic polymers allows the small dye molecules propidium idodide (PI) and fluorescein (FITC) to diffuse in and out of the cells. CLSM images also show internalization of PLL labeled with FITC dye. In contrast, controls of membrane permeability using the neutral linear polymers PEG and PVA show dramatically less LDH and LUC leakage and no enhanced dye diffusion. Taken together, these data are consistent with the hypothesis that polycationic polymers induce the formation of transient, nanoscale holes in living cells and that these holes allow a greatly enhanced exchange of materials across the cell membrane.

Nanofluids a simple product of the emerging world of nanotechnology are suspensions of nanoparticles in conventional base fluids such as water, oils, or glycols. In the present paper uniform suspension of Al2O3 nanoparticle in water of different concentration have been prepared. The ultrasonic velocity, absorption, density and viscosity measurements were carried out in the concentration range of 0.2 wt % to 1.0 wt % and temperature range between 2930K to 3130K at frequencies of 2 MHz and 10 MHz.Ultrasonic velocity and absorption measurements are carried out by MHF-400 high frequency pulser receiver. To maintain desired accurate constant temperature Plasto Craft thermostat with accuracy of ± 0.10C in temperature range -100C to 950 C is used. Variations of these parameters are interpreted in terms of intermolecular interactions. The variation of acoustic and thermodynamic parameters indicates different kind of molecular interactions, physico-chemical behaviour and their strength.

Ellagic acid, a plant-derived polyphenol, inhibits γ-radiation (hydroxyl radical) induced lipid peroxidation in rat liver microsomes in a dose-and concentration-dependent manner. Its antioxidant capacity has been estimated using the 1,1-diphenyl-2-picrylhydrazyl radical assay. To understand the actual mechanisms involved in antioxidant activity and the free radical scavenging ability,a nanosecond pulse radiolysis technique has been employed. The rate constants for the reactions of several reactive oxygen species and reactive nitrogen species such as hydroxyl, peroxyl, and nitrogen dioxide radicals have been found to be in the range of 10 6 -10 9 M -1 s -1 . The ellagic acid radicals have been characterized by the absorption spectra and decay kinetics. Studies on the reactions of ellagic acid with the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical and the radicals of ellagic acid with ascorbate have been used to estimate its one-electron reduction potential. Ellagic acid has also been found to be a good scavenger of peroxynitrite. Using stopped-flow reaction analyzer with absorption detection, the rate constant for this reaction has been determined to be 3.7 × 10 3 M -1 s -1 . The electron spin resonance spectra of the oxidized ellagic acid radicals have been recorded by horseradish peroxidase and hydrogen peroxide method.

By combination of fast magic-angle spinning (MAS) and detecfor the central transition on the order of hundreds of kilohertz tion of the free-induction decay during a rotor-synchronized quadgenerally reduces the spectral sensitivity. rupolar Carr-Purcell-Meiboom-Gill (QCPMG) train of refocus- We recently introduced the QCPMG experiment, i.e., the ing pulses, the sensitivity of quadrupolar-echo MAS NMR spectra quadrupolar version (9, 10) of the Carr-Purcell-Meiboomfor the central transition of half-integer quadrupolar nuclei exhib-Gill (CPMG) 12) experiment, as a means to increase iting large quadrupolar couplings may be significantly enhanced. the sensitivity of quadrupolar-echo (QE) spectra (13)

In this work, a quantitative structure-activity relationship (QSAR) for some tacrine derivatives inhibitors of acetylcholinesterase was modeled using ligand-receptor interconnection interaction space. The descriptors were obtained by multivariate image analysis (MIA) of each molecule. Docking studies were performed to determine the best conformers of inhibitors. In the first step, the best pose of all the ligands was selected. Afterward, an MIA-QSAR model using ligand-receptor interconnection data was developed. The pool of descriptors was compressed by principal component analysis (PCA). Variable selection was carried out by genetic algorithm (GA) followed by model building using the support vector machine (SVM) regression method. The validation of the model's predictive ability was studied by a validation set containing 11 individual compounds. The Q2, r2 and, ∆r_m^2 test prediction values for PCA-GA-SVM model were 0.62, 0.89 and 0.145, respectively. After validating the resul...

DNA is emerging as a versatile structural material at the nanoscale due to predictable formation of Watson-Crick base-pairs and the ability to form branched constructs. Using these principles, constructs ranging in size from tens to thousands of base-pairs are routinely formed in solution with predictable structure in two or even three dimensions. Most DNA construction is done in buffered solution where the DNA is in a native state, able to assemble spontaneously and disassemble through external stimuli such as temperature. Here we explore both the reversible formation of DNA functionalized to bind to lipid bilayers and the light harvesting properties of DNA functionalized with light absorbing dyes.