Miracle-dz/UniFAR-FTUs huggingface dataset:
Preparation and swelling behavior of biodegradable hydrogels based on α,β‐poly(N‐2‐hydroxyethyl‐DL‐aspartamide)

Biodegradable polymers and the hydrogels have been increasingly applied in a variety of biomedical fields and pharmaceutics. α,β-Poly(N-2-hydroxyethyl-DL-aspartamide), PHEA, one of poly(amino acid)s with hydroxyethyl pendants, are known to be biodegradable and biocompatible, and has been studied as an useful biomaterial, especially for drug delivery, via appropriate structural modification. In this work, hydrogels based on PHEA were prepared by two-step reaction, that is, the crosslinking of polysuccinimide, the precursor polymer, with oligomeric PEG or PEI-diamines and the following nucleophilic ring-opening reaction by ethanolamine. Soft hydrogels possessing varying degrees of gel strength could be prepared easily, depending on the amount of different crosslinking reagents. The swelling degrees, which were in the range of 10–40 g–water/dry gel, increased somewhat at higher temperature, and also at alkaline pH of aqueous solution. A typical hydrogel remained almost unchanged for 1 week, at 37°C in phosphate buffer of pH 7.4, and then seemed to degrade slowly as time. A porous scaffold could be fabricated by the freeze drying of water-swollen gel. The PHEA-based hydrogels have potential for useful biomaterial applications including current drug delivery system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3741–3746, 2003
Synthesis, Solution‐State and Solid‐State Structural Characterization of Monocationic Nitrido Heterocomplexes [M(N)(DTC)(PNP)]+ (M = 99Tc, Re; DTC = Dithiocarbamate; PNP = Heterodiphosphane)

Mono-cationic nitrido heterocomplexes of general formula [M(N)(DTC)(PNP)]+ (where M is 99Tc or Re, DTC is the mono-anionic form of a dithiocarbamate ligand, and PNP is a diphosphane ligand with a tertiary amine-containing five-membered spacer) were prepared by ligand-exchange reactions with the labile precursors [M(N)Cl2(PPh3)2] in dichloromethane/alcohol mixtures. The molecular structure of the representative rhenium complex [Re(N)(dedc)(pnp2)][PF6] (1) displays a distorted, square-pyramidal geometry with the dithiocarbamate sulfur and the diphosphane phosphorus atoms spanning the four coordination positions on the equatorial plane. If the additional interactions between the nitrido nitrogen and the weakly bonded transN-diphosphane heteroatom, the molecular geometry can be viewed as pseudo-octahedral. The structure in solution, as established by multinuclear NMR spectroscopy and ESI spectrometry, is monomeric, and identical to that shown in the solid state. Replacement of the phenyl groups on the phosphorous atoms in complexes 1, 2, 5, and 6 with alkyl groups modified neither the course of the reaction nor the composition of the resulting complexes. These results, together with the observation that no symmetrical complexes containing two identical bidentate ligands were produced in these reactions, strongly supports the conclusion that a mixed coordination sphere, composed by a combination of π-donor and π-acceptor atoms around the [M≡N]2+ group, constitutes a highly stable system. Compounds containing dangling alkyl-substituted groups in the outer sphere (3, 4, 7, and 8) were fully characterized by multinuclear NMR spectroscopy and ESI mass spectrometry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Total Syntheses of AF-2785 and Gamendazole—Experimental Male Oral Contraceptives

Abstract Both AF-2785 and gamendazole are experimental male oral contraceptives. The total syntheses of these two compounds are achieved in good yields. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT
Electronic structure of manganese doped pentacene

The desire for low cost electronics has led to a huge increase in research focused on organic materials. These materials are appealing due to their unique electrical and material-processing properties and are rapidly being adopted in old and new electronic applications. To create practical devices requires a further understanding of the charge transport properties of the unique anisotropic molecular crystal structures. This work looks at how doping with the transition-metal element manganese can alter the electronic structure of the organic material pentacene. It has been found that using manganese as a dopant provides novel physical characteristics previously not encountered in organic field effect transistors based on pentacene. These organic thin films were characterized using X-ray absorption spectroscopy and the results compared to computational density functional theory analysis.
Fluorescent Polycytosine-Encapsulated Silver Nanoclusters

Small silver nanoclusters are synthesized using polycytosines as matrices. Different size silver nanoclusters ranging from Ag1 to Ag7 exhibit bright emission maxima at blue (480nm), green (525nm), red (650nm), and IR (720nm) wavelengths with varying the excitation wavelengths. With electrophoresis, correlation of emission with mass spectra, the Ag cluster sizes are identified with blue emitters as Ag5, green emitters as Ag4, red emitters as Ag3, and IR emitters as Ag2. Ag4 and Ag5 appear to be partially oxidized while Ag2 and Ag3 are likely fully reduced. Silver cluster stability and their dynamics are observed from silver clusters encapsulated by polycytosine (Cm:Agn). From length study of polycytosine, the longer the polycytosine is, the more stable the larger clusters such as Ag5 are. In time-dependent optical measurements, isosbestic points are observed from Cm:Agn by converting red and IR species into blue and green species, while in the case of temperature-dependent optical properties, with increasing temperature, the blue (oxidized Ag5) and green (oxidized Ag4) emitters convert into the red (Ag3) and IR (Ag2) emitters. NaCl-dependent optical measurements support the assignments of oxidized and fully reduced silver emitters. Circular dichroism (CD) is used to investigate conformational changes in Cm and Cm:Agn with varying conditions (time, temperature and NaCl) and the studies indicate that no conformational changes in Cm:Agn are observed from the time and temperature, while the conformational changes in Cm:Agn are observed from the NaCl studies. From pH-dependent emission study of Cm:Agn, the silver nanocluster dynamics slow down at high pH. Using confocal microscopy technique, single molecules on IR species, C12:Ag2 are investigated and demonstrate that C12:Ag2 is brighter and more photostable than Cy5 which is known to be one of the best IR dyes. With low excitation power, molecules can be monitored for hours, giving bright blinking free, stable fluorescence. The photophysics of this new dye make it a promising candidate for single molecule studies in biological applications.
Colloids at liquid crystal interfaces

This thesis presents a study of colloidal particles dispersed in thermotropic liquid crystals. It has a specific focus on colloids in the presence of an interface between the liquid crystal and an isotropic fluid. Three systems are studied: colloids trapped at a planar interface between a cholesteric liquid crystal (CLC) and an isotropic oil, nematic emulsions with interfacial colloids and the influence of colloids on the phase transition kinetics of the cholesteric blue phase. Experiments are carried out using polarising optical and confocal microscopy. By combining these techniques, the director field of the liquid crystals could be imaged in combination with precise observation of the colloid locations. Custom image analysis algorithms are developed to extract the information. In the first system, we create an interface between a cholesteric liquid crystal and an isotropic liquid. Homeotropic anchoring leads to a well aligned cholesteric layer and the formation of the fingerprint texture. Fluorescent colloidal particles with planar surface anchoring are dispersed in the CLC. A majority of these particles decorate the interface. The final distribution of particles perpendicular to the interface has a clear dependence on the particle size. In the plane of the interface, surface defects form a template for the colloids. The second system is a particle dispersion within a short pitch CLC which exhibits a blue phase. The colloidal particles and associated defects act as nucleation sites for the blue phase in the cholesteric to blue phase transition. Colloidal particles cause localised melting from the blue phase to the isotropic phase and lead to a larger temperature range for coexistence between isotropic and blue phases. Furthermore, the isotropic regions can be faceted, their shape and size is controlled by the blue phase elasticity. In the final system, a nematic emulsion is created. Droplets of nematic LC are dispersed in water. Colloidal particles initially mixed into the liquid crystal
Highlights From Pathways to Desistance: A Longitudinal Study of Serious Adolescent Offenders

ojjdp.gov Office of Juvenile Justice and Delinquency Prevention The Pathways to Desistance Study is a large collaborative, multidisciplinary project that is following 1,354 serious juvenile offenders ages 14–18 (184 females and 1,170 males) for 7 years after their conviction (for more detailed information, see “Study Design”). 1 This study has collected the most comprehensive data set currently available about serious adolescent offenders and their lives in late adolescence and early adulthood. It looks at the factors that lead youth who have committed serious offenses to continue or desist from offending, including individual maturation, life changes, and involvement with the criminal justice system.
Nitric oxide chemistry effects in hypersonic boundary layers

Simulations of gas seeding into a hypersonic boundary-layer flow were performed using OpenFOAM® to investigate and quantify errors associated with quantitative planar laser-induced fluorescence thermometry and velocimetry techniques. A modified version of the compressible rhoCentralFoam solver was used to simulate multicomponent chemically reactive flows. Simulations replicated conditions used in NASA Langley Research Center’s 31 in. Mach 10 facility with a wedge model oriented at various angles of attack with respect to the freestream flow in the test section. Adverse chemistry effects from the reaction of nitric oxide with molecular oxygen were investigated at various facility running conditions. Specifically, the effect of heat release on velocity and temperature profiles that would be obtained using the nonintrusive laser measurement techniques was assessed. The effect of any potential adverse chemistry reactions was found to be negligible.
Electroosmotic Flow in Nanoscale Parallel-plate Channels: Molecular Simulation Study and Comparison with Classical Poisson–Boltzmann Theory

Molecular dynamics simulations have been carried out for simple electrolyte systems to study the electrokinetically driven osmotic flow in parallel-plate channels of widths ∼10–120 nm. The results are compared with the classical theory predictions based on the solution to the Poisson–Boltzmann equation. We find that despite some of the limitations in the Poisson–Boltzmann equation, such as assumption of the Boltzmann distribution for the ions, the classical theory captures the general trend of the variations of the osmotic flow with channel width, as characterized by the mobility of the fluid in channels between ∼10 and 120 nm at moderate to low ion concentration. At moderate concentration (corresponding to relatively low surface potential), the classical theory is almost quantitative. The theory and simulation show more disagreement at low concentration, primarily caused by the high surface potential where the assumption of Boltzmann distribution becomes inaccurate. We discuss the limitations of the Poisson–Boltzmann equation as applied to the nanoscale channels.
The solution of the time‐dependent Schrödinger equation by the (t,t’) method: Theory, computational algorithm and applications

A new powerful computational method is introduced for the solution of the time dependent Schrodinger equation with time‐dependent Hamiltonians (not necessarily time‐periodic). The method is based on the use of the Floquet‐type operator in an extended Hilbert space, which was introduced by H. Sambe [Phys. Rev. A 7, 2203 (1973)] for time periodic Hamiltonians, and was extended by J. Howland [Math Ann. 207, 315 (1974)] for general time dependent Hamiltonians. The new proposed computational algorithm avoids the need to introduce the time ordering operator when the time‐dependent Schrodinger equation is integrated. Therefore it enables one to obtain the solution of the time‐dependent Schrodinger equation by using computational techniques that were originally developed for cases where the Hamiltonian is time independent. A time‐independent expression for state‐to‐state transition probabilities is derived by using the analytical time dependence of the time evolution operator in the generalized Hilbert space. Ill.
New developments in direct shape determination from small angle scattering

Improvements in the shape determination method based on multipole expansion [Stuhrmann (1970), Z. Phys. Chem. (Frankfurt am Main), 72, 177–198] are described. Fast algorithms for evaluating shape scattering from the multiple coefficients are developed. The relationship between the resolution in real and reciprocal space is established. The improved technique is verified by means of model calculations. It is shown that the low-resolution shape estimation can be performed as a straightforward procedure. Shape refinement at higher resolution is ambiguous; a variety of shapes can be generated which fit the given intensity curve neatly. A criterion is given to select the most plausible solution in higher-resolution studies.
An Electrochemical Study of the Influence of Marinobacter aquaeolei on the Alteration of Hydrothermal Chalcopyrite (CuFeS2) and Pyrite (FeS2) under Circumneutral Conditions

Pyrite and chalcopyrite are the two most abundant sulphides observed in seafloor hydrothermal systems. The alteration of sulphides is primarily controlled by reactions on the mineral surfaces and Fe(II)-oxidizing bacteria closely related to Marinobacter aquaeolei are thought to play a major role in iron oxidation under circumneutral conditions. We assessed the influence of M. aquaeolei on the electroactivity of FeS2 and CuFeS2 minerals under circumneutral conditions. Samples for the experiments were obtained from the Trans-Atlantic Geotraverse (TAG) hydrothermal mound (field), 26 °N on the Mid-Atlantic Ridge and Ireland (CuFeS2)]. The experimental approach relied on voltammetry and scanning electrochemical microscopy (SECM). The tip-substrate voltammetry mode of SECM was found to be particularly suitable to probe the major redox processes of those minerals and permitted an assessment of the microorganisms influence on these processes. M. aquaeolei was found to enhance FeS2 and CuFeS2 oxidation, particularly under suboxic conditions. M. aquaeolei also significantly enhances Fe dissolution under oxic circumneutral conditions but suppresses the dissolution of most other elements compared to abiotic conditions. Under abiotic conditions the surfaces of the minerals are rapidly passivated when oxygen is available; while addition of M. aquaeolei significantly hinders the passivation of chalcopyrite, no passivation of the pyrite surface is observed. This study demonstrates the ability of Marinobacter aquaeolei to enhance oxidation of FeS2 and CuFeS2 under circumneutral conditions and supports the involvement of Marinobacter species in weathering reactions on the seafloor and the control of the ultimate fate of sulphide deposits.
Notes on the Composition of Patchouli Oil (Pogostemon cablin (Blanco) Benth.)

Abstract A study of commercial oils of Patchouli [Pogostemon cablin (Blanco) Benth. ] from three regions in Asia found no evidence for the presence of allo-aromadendrene in any of the oils, indicating that previous reports were either adulterated with Gurjun Balsam (Dipterocarpus sp.) or more likely misidentified. Traces of acetophenone, 9-epi-β-caryophyllene, (E)-4,8-dimethylnona-1,3,7-triene, (E,E)-farnesol, (E,E)-farnesyl acetate, hexahydrofarnesyl acetone, isovaleric acid, 2-methylbutyric acid, 5-methylfurfural, 1-octen-3-one, 2-pentylfuran, phenylacetaldehyde, phytol, toluene, and p-vinylguaiacol were identified, possibly for the first time, in Patchouli oil.
Growth of high-density vertically aligned arrays of carbon nanotubes by plasma-assisted catalyst pretreatment

A plasma-assisted thermal pretreatment of catalyst films (Ni, Co, or Fe) greatly facilitates the direct growth of high-density vertically aligned arrays of small diameter carbon nanotubes (CNTs) on conductive TiN by purely thermal chemical vapor deposition. Purely thermal catalyst pretreatment gives limited or no growth. The plasma-assisted pretreatment promotes a stronger catalyst-support interaction, which reduces catalyst mobility and hence stabilizes smaller catalyst particles with a higher number density.
Interfacial Reaction of W/Cu Examined by an n-body Potential through Molecular Dynamics Simulations

Concerning the possible barrier function of W in the case of Cu metallization technology, the interfacial reaction between the equilibrium immiscible Cu and W was studied by molecular dynamics simulations, based on a proven realistic Cu–W potential derived under the embedded atom method. The simulation results revealed that the Cu (W) atoms did not diffuse into the W (Cu) lattice within a temperature range of 300–900 K. Moreover, even a disordered interlayer was preset at the Cu–W interface, mutual diffusion was not detectable and the disordered interlayer did not expand either, while it was reported to occur in the Ta/Cu bilayer at around 450–600°C.
Synthesis of Biogasoline from Ethanol over Hydroxyapatite Catalyst

Plant-derived, dehydrated ethanol was effectively converted to biogasoline in a one-step process on a highly active nonstoichiometric hydroxyapatite (HAP) catalyst. The biogasoline had a research octane number of 99 and comprised chiefly hydrocarbons from C6 to C10 as well as oxygenates not generated in the methanol-to-gasoline (MTG) process using zeolite. To confirm a proposed scheme for the synthesis of gasoline from ethanol over HAP, alcohol conversions were carried out using paired combinations of five different alcohols with ethanol. Results indicated that: (1) normal and branched alcohols were obtained by the Guerbet reaction from normal alcohols, (2) dienes were synthesized by the Lebedev reaction, and (3) aldehydes and olefins were mainly synthesized by dehydrogenation and dehydration of branched alcohols respectively.
Models of gas-grain chemistry in dense interstellar clouds with complex organic molecules

Models of the chemistry of dense interstellar clouds are presented in which both gas-phase and grain-surface chemistry occur. The dust grain and gas temperatures are fixed at 10 K, and the gas density n = n(H) + 2n(H 2 ) remains approximately at 2 × 10 4 cm -3 in these models, which are designed primarily to represent the chemistry occurring in dark clouds. We utilize previous ideas on what constitutes the most likely reactions to occur on large classical grains. Grain reactions that produce molecules as complex as those in our previous models of gas-phase chemistry are included to help elucidate the role of grains in the synthesis of organic molecules
Solvents from nature

In this perspective, a personal journey from solvent to solvent is presented to demonstrate how environmentally friendly solvents can be part of the solution of various chemical challenges. Solvents are important components of Nature to provide one or more liquid phases for chemical reactions and processes. While some solvents are available from Nature even in large quantities, most of the solvents are man-made. Historically, solvents were developed and/or selected to help the chemical or physical objectives of the user(s) only. With the increasing importance of local and global health and environmental issues, including the introduction of green chemistry and the molecular approach for pollution prevention, the potential impacts of solvents became important selection tools. One of the key principles of green chemistry is the elimination of solvents in chemical processes or the replacement of hazardous solvents with environmentally benign solvents. The development of solvent-free alternative processes is the best solution, especially when either one of the substrates or the product is a liquid and can be used as the solvent of the reaction. However, if solvents are crucial to a process we should select from solvents that will have no or limited impact on health and the environment.
Half‐collision description of final state distributions of the photodissociation of polyatomic molecules

The full three‐dimensional quantum mechanical scattering equations, describing direct photodissociation and weak predissociation from initially selected levels, are analyzed within a formulation which permits the use of the different nuclear coordinate systems appropriate to the bound and dissociative surfaces. The coupled two surface scattering equations satisfy the physical boundary conditions of regularity at the origin and purely outgoing flux on the dissociative surface (with incoming photon flux.) These equations are transformed, both in integral and differential equation forms, into single surface half‐collision equations wherein the initial bound state wave function, multiplied by the appropriate coupling operator, is propagated on the dissociative surface with the physical boundary conditions. These driven equations are shown to yield transition amplitudes which are equivalent to the transition amplitudes obtained from the Gell‐Mann and Goldberger (GMG) scattering formulation which employs plane .
Acidity of Wood

A new method is described for chemical analysis of the insoluble acids contained in wood. It is based on the reaction of wood acids with aqueous sodium acetate to liberale an equivalent amount of acetic acid, pH titration of which gives the total acid content. Soluble acids are determined by water extraction and titration. Subtraction of soluble from total acids gives the insoluble or 'bound' acid in wood. Bound acids concentration is found to correlate better with gel times of urea-formaldehyde condensation than soluble or total acids. The implications of these findings for adhesive bonding of wood are pointed out.
Investigations on Caesium-free Alternatives for H- Formation at Ion Source Relevant Parameters

Negative hydrogen ions are efficiently produced in ion sources by the application of caesium. Due to a thereby induced lowering of the work function of a converter surface a direct conversion of impinging hydrogen atoms and positive ions into negative ions is maintained. However, due to the complex caesium chemistry and dynamics a long-term behaviour is inherent for the application of caesium that affects the stability and reliability of negative ion sources. To overcome these drawbacks caesium-free alternatives for efficient negative ion formation are investigated at the flexible laboratory setup HOMER (HOMogenous Electron cyclotron Resonance plasma). By the usage of a meshed grid the tandem principle is applied allowing for investigations on material induced negative ion formation under plasma parameters relevant for ion source operation. The effect of different sample materials on the ratio of the negative ion density to the electron density nH− /ne is compared to the effect of a stainless steel refere.