Miracle-dz/UniFAR-FTUs huggingface dataset:
Amino‐termined poly(L‐lactide)s as initiators for the polymerization of N‐carboxyanhydrides: synthesis of poly(L‐lactide)‐block‐poly(α‐amino acid)s

Poly(L-lactide)-block-poly(L-amino acids) block copolymers were prepared via polymerization of α-amino acid N-carboxyanhydrides with amino-terminated poly(L-lactide)s as macroinitiators. Two types of macroinitiators were used, one with an aminopropoxy head group (number-average molecular weight M n = 22000) and the other one with a phenylalanine end group (M n = 18000). The first macroinitiator was obtained by polymerization of (L,L)-lactide with an initiator prepared in situ from diethylzinc Et 2 Zn and N-tert-butoxycarbonyl-1-amino-3-propanol, followed by deprotection of the amino group. The second macroinitiator was obtained by endcapping of poly(L-lactide) with N-tert-butoxycarbonylphenylalanine and deprotection of the amino group. 1 H- and 13 C NMR spectroscopies confirm the block structure of the copolymers obtained. In differential scanning calorimetry curves only one melting transition characteristic of the poly(L-lactide) block is observed, on further heating decomposition occurs. By thermogravimetry two steps of decomposition are observed, the first one being assigned to the decomposition of the poly(L-lactide) block, and the second one to that of the poly(amino acid) block, by comparison with the thermal behaviour of the corresponding homopolymers.
Bond Energetics at Intergranular Interfaces in Alumina-Doped Silicon Nitride

In Si 3 N 4 ceramics sintered with Al 2 O 3 , the interfacial strength between the intergranular glass and the reinforcing grains has been observed to increase with increases in the aluminum and oxygen content of the epitaxial β-Si 6-z Al z O z N 8-z layer that forms on the Si 3 N 4 grains. This has been attributed to the formation of a network of strong bonds (cross bonds) that span the glass-crystalline interface. This proposed mechanism is considered further in light of first-principles atomic cluster calculations of the relative stabilities of bridge and threefold-bonded atomic fragments chosen to represent compositional changes at the glass/Si 3 N 4 grain interface. Calculated binding energies indicate Al-N binding is favorable at the Si 3 N 4 grain surface, where aluminum occupancy can promote the growth of SiAION, further enhancing the cross-bonding mechanism of interfacial strengthening.
Field theoretical approach to inhomogeneous ionic systems: thermodynamic consistency with the contact theorem, Gibbs adsorption and surface tension

Using a statistical field approach we investigate the structure of an electrolyte solution in contact with a neutral impenetrable wall. The Hamiltonian contains the Coulomb interaction and the ideal entropy. At the level of the quadratic approximation, the Hamiltonian yields the Debye-Hückel theory in the bulk. Analytic expressions of the charge-charge and potential-potential inhomogeneous correlation functions are obtained. Exact asymptotic results for point ion charge correlation functions are obtained and the profile for the fluctuation of the electric potential is calculated. We also consider the term beyond the quadratic expansion of the ideal entropy in the Hamiltonian. With this term a higher order coupling between charge density and number density produces a non-trivial profile for the total ion density. This density profile is consistent with the contact theorem and the related surface tension calculated from the Gibbs adsorption isotherm.
Morphological Factors Relating to the Penetration of Liquids into Wood

The path of penetration of liquids into woods is of considerable interest in the technology of prccesses such äs wood preservation and pulping. In wood preservation processes the site of the preservative may in part be determined by the path of penetration. In pulping this path determines the region of initial attack on the fibre wall and culminates in the Separation of the fibres from each other. Studies to determine the path of penetration have been reviewed by Jensen, Fogelberg and Johanson (1960). The bordered pits between tracheids of gymnosperms have long been recognised äs potential paths of penetration between cells. In fresh wood this was demonstrated (Bailey, 1913) by the study of the movement of carbonblack suspensions. It was observed by Bailey that the carbon particles accumulated in the pit membranes and since some particles passed through the wood, Bailey also concluded that the pit membrane was perforated. This line of work was subsequently followed by Frenzel (1929) and later by Liese (1956) who showed that the perforations of the pit membrane measure up to 2,000 A in width. Bailey (1913) has also pointed out that rays, especially in those species containing ray tracheids, may play a significant part in the lateral movement of liquids in conifers. Schulze and Theden (1950) demonstrated that the ray cells provide channels of penetration into the wood from which liquids may pass to the tracheids through the pits. Büro and Büro (1959) demonstrated that in Pinus sylvestris liquids pass through the bordered pits between tracheids during penetration. Aspiration of the bordered pits in heartwood is generally accepted äs being a major factor contributing to the difficulty of penetration of liquids into the heartwood of gymnosperms (Hunt and Garratt, 1953). In a pulping study of spruce, using the sulphite process, Lange (1947) observed that the change in concentration of lignin in the middle lamella zone during pulping is greater than the change in concentration nearer the lumen and concluded that the pulping medium reached the middle lamella before the lumen. Lange considered that diffusion topk place into the middle lamella zone from the pit chambers. Earlier pulping studies such äs those of Abrams (1921), Harlow (1931) and Bixler (1938) were carried out on wood sections and so gave no indication of the path of penetration.
Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

Abstract This study concerns with distribution, type, and structure of carboxylic acids in the 200–550°C distillates of Bohai crude oil. The acids, isolated by aqueous alcoholic sodium hydroxide, were converted into corresponding methyl esters with BF3 as catalyst. The chemical structure of these carboxylic acids and distribution of their various components in different distillates were studied in detail by IR, VPO, MS, and elemental analysis. The results show that the carboxylic acids in Bohai crude oil are mainly composed of naphthenic acids and branched chain fatty acids, and the content is high in distillates at about 405°C and 505°C. With increase of boiling temperature of distillates, the content of naphthenic acids increases gradually. The ring numbers of naphthenic acids in diesel distillate are mainly 1–3, and those in lubricant distillate are mainly 1–6.
Competitive Energy and Electron-Transfer Reactions of the Triplet State of 1-Nitronaphthalene: A Laser Flash Photolysis and Time-Resolved Resonance Raman Study

A laser flash photolysis and time-resolved resonance Raman study of 1-nitronaphthalene (1NN) in sodium nitrite and trans-stilbene (tS) solution, in both polar and nonpolar solvents, is reported. The transient absorption data suggest that 1NN acts as an electron acceptor with nitrite ions and tS in polar solvents but undergoes energy transfer to tS in nonpolar solutions. At high concentrations of tS the electron-transfer reaction leads ultimately to the formation of a dimer radical cation (tS2)•+. We report here the Raman spectrum of the radical anion of 1-nitronaphthalene and the differences in the Raman spectra of the monomeric and dimeric radical cation of trans-stilbene in the 1500−1650 cm-1 region. The switch from energy to electron transfer when going from nonpolar to polar solutions is discussed in terms of the electronic and nuclear factors that govern these reactions.
Noise in Submicron Metal–Oxide–Semiconductor Field Effect Transistors: Lateral Electron Density Distribution and Active Trap Position

Experiments were carried out for the n-channel devices, processed in a 0.3 µm spacer less complementary metal–oxide–semiconductor technology. Random-telegraph-signal measurements were performed for the constant gate voltage. It is supposed that electron concentration in the channel decreases from the source to the drain contact. Lateral component of the electric field is inhomogeneous in the channel and it has a minimum value near the source and reaching the maximum value near the drain electrode. Drain current is given by two components – diffusion and drift ones. Diffusion current component is independent on the x-coordinate and it is equal to the drift current component for the low electric field. The model explaining the experimentally observed capture time constant dependence on the lateral electric field and the trap position is given. From the dependence of the capture time constant τc on the drain current could be calculated longitudinal coordinate of the trap position.
Numerical study on the combustion and emission characteristics in a direct-injection diesel engine with preheated biodiesel fuel

The effect of the biodiesel fuel injection temperature on the combustion and emissions characteristics is investigated numerically in a direct-injection diesel engine. In this three-dimensional simulation study, methyl butanoate (MB) is applied as the surrogate of biodiesel fuel, and a detailed chemical kinetic mechanism of MB containing 41 species and 150 reactions is implemented. The results indicate that preheating the biodiesel fuel plays an important role in the spray and atomization processes, especially when the engine operates under the low-temperature condition. Furthermore, the in-cylinder flow turbulence kinetic energy increases and the flame lift-off length shortens with an increase in the fuel injection temperature. The increase in the fuel injection temperature results in a decrease in the equivalence ratio in the fuel-rich area. The results also reveal that both soot and nitrogen oxide emissions are reduced by preheating the biodiesel fuel.
Spectroscopy of trivalent europium in gel-derived silica glasses

Abstract Luminescence spectra of Eu3+ in sol-gel-derived silica (SiO2) samples are reported and discussed as a function Eu3+ concentration and of heating. Lifetimes, linewidths and Stark splittings of the transitions are used for monitoring structure evolutions of the gel network; the data in the interval 25–250°C allow us to describe the general behaviour of the system during SiO, gel→txerogel transition.
Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Folic Acid using a Oxytetracycline-Terbium(III) Probe

Abstract A new spectrofluorimetric method was developed for the determination of trace amounts of folic acid using oxytetracycline–terbium ion complex as a fluorescent probe. In the buffer solution of pH 6.00, folic acid remarkably reduced the fluorescence intensity of the oxytetracycline–terbium complex at λ = 545 nm. The reduced fluorescence intensity of the Tb3+ ion was proportional to the concentration of folic acid. Optimum conditions for the determination of folic acid were investigated. This method was simple, practical, and relatively free of interference from coexisting substances. Furthermore, it was successfully applied to assess folic acid in tablet, injection, and urine samples.
Effects of Quenching and Annealing on Ionic Conductivity and on Dislocation Decorability in Silver Chloride

Pure silver chloride crystals, when cooled rapidly from high temperatures, show enhanced ionic conductivity which may be attributed to quenched‐in Schottky defects. From the annealing out of this extra conductivity one deduces that for an associated vacancy pair the binding energy is 0.42 ev and the migration energy is ≥1.0 ev. The decorability of interior dislocations by swept‐in photoelectrons is also discussed and is shown to be sensitive to the purity of the crystal.
Metrology of 1–10 nm thick CNx films: Thickness, density, and surface roughness measurements

Ultrathin nitrogenated carbon (CNx) films were synthesized using pulsed dc magnetron sputtering. The influence of substrate tilt angle and rotation speed on surface roughness was explored. Atomic force microscopy studies showed that the smoothest films were obtained at substrate tilt of 45° and rotation speed 20–25 rpm, corresponding to 2–3 rotations per deposited atomic layer. The root-mean-square surface roughness under these optimum conditions is ∼0.3 nm when sampled over 20×20 μm2 areas, increasing to ∼0.4 nm when sampled over ∼0.05×3 cm2 using x-ray reflectivity measurements. In addition, x-ray reflectivity measurements showed that the mass density of these CNx films is ∼2.0 gm/cc, independent of film thickness from ∼1 to 10 nm, consistent with ion beam analysis.
Photochromic Properties of Perhydro- and Perfluorodithienylcyclopentene Molecular Switches

Various substituted phenylthienyl perhydro- and perfluorocyclopentenes have been synthesized in order to compare their spectroscopic and photochromic properties. The difference in the electron densities of the central cyclopentene moieties in the perhydrocyclopentene and perfluorocyclopentene molecular switches has only a small effect on the absorption maxima of the electronic spectra, but causes some subtle changes in substituent and solvatochromic effects. The photochromic behaviour is remarkably similar, and both type of switches combine excellent quantum yields (0.6) with high degrees of photoconversion (> 0.85). The main difference is the lower photochemical and thermal stability of the perhydrocyclopentene molecular switches. It is concluded that in most studies the perhydrocyclopentenes are an excellent alternative for the perfluorocyclopentenes, while the perfluorocyclopentenes might be better suited for applications such as data storage, which depend critically on fatigue resistance and thermal stability. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
Effects of plant residues and calcite amendments on soil sodicity

The effects of wheat, potato, sunflower, and rape residues and calcite were evaluated in soil that received sodic water. These materials were added to a sandy-loam soil at a rate of 5%, after which the treated soils were incubated for 1 month at field-capacity moisture and a temperature of 25°C–30°C. Column leaching experiments using treated soils were then conducted under saturated conditions using water with three sodium-adsorption ratios (SAR) (0, 10, 40) with a constant ionic strength (50mmol L–1). The results indicated that the application of plant residues to soils caused an increase in cation-exchange capacity and exchangeable cations. Leaching experiments indicated that the addition of plant amendments led to increased Na+ leaching and decrease in exchangeable-sodium percentage (ESP). The ESP of the control soil, after leaching with solutions with an SAR of 10 and 40, increased significantly, but the level of sodification in soils treated with plant residue was lower. Such decreases of soil ESP were greatly affected by the type of plant residues, with the order of: potato-treated soil > sunflower-treated soil > rapetreated soil > wheat-treated soil > calcite-treated soil > control soil.
Functionalized O-carboxymethyl-chitosan/polyethylenimine based novel dual pH-responsive nanocarriers for controlled co-delivery of DOX and genes

A novel dual pH-sensitive co-delivery system, programmed to respond to tumor extracellular pH (6.0–7.0) and intracellular pH (4.5–6.5) environments, was designed for the controlled co-delivery of DOX and genes. Tumor intracellular pH-sensitive cationic doxorubicin (DOX)–poly(ethyleneimine) (PEI) conjugates (DOX–PEI, DP) were synthesized via pH-sensitive hydrazone bonds. As O-carboxymethyl-chitosan (CMCS) possesses cationic charges under pH 6.5 and is anionically charged above pH 7.0, tumor extracellular pH (6.0–7.0) triggered charge reversal CMCS–poly(ethylene glycol) (PEG)–aspargine–glycine–arginine (NGR) copolymers (CMCS–PEG–NGR, CPN) were synthesized. The two materials with different properties help to construct the dual pH-sensitive co-delivery system. First, the cationic DP interacts with anionic pDNA to form a DOX and gene co-loaded DP/pDNA (DPD) core. Then, anionic CPN is adsorbed on the surfaces of the positive charged DPD to form dual pH-sensitive CPN/DPD (CDPD). CDPD and DPD exhibited spherical shapes, uniform particle size distributions (137.4 ± 2.7 nm and 80.0 ± 4.2 nm, respectively), and positive zeta potentials (8.25 mV and 23.59 mV, respectively). Targeted cellular uptakes of CDPD were confirmed (cellular uptakes of CDPD were 92.49 ± 2.28% and 67.82 ± 0.07% in CD13-positive A549 cells and CD13-negative HepG2 cells, respectively). The dissociation of CPN from CDPD at acidic tumor tissue was evaluated (transfection efficiencies of CDPD at pH 7.4 and pH 6.0 were 11.43 ± 0.59% and 20.20 ± 1.21%, respectively). The internalized DPD programmable release of DOX and pDNA was investigated under simulated endosomal conditions. The results suggest that dual pH-sensitive CDPD was conducive to targeted delivery and the novel functional materials ensured the successful construction of novel dual pH-sensitive CDPD using a simple method.
Voltammetric Response of Glutathione and 3‐Mercaptopropionic Acid Self‐Assembled Monolayer Modified Gold Electrodes to Cu(II)

Glutathione (GSH) self-assembled monolayer (SAM) is prepared on a gold electrode. It has been found that the modified electrode exhibits selective response to cupric ions, and the Cu(II) wave appears at about 0.3 V (vs. SCE). Conditions of determination are optimized, including parameters that govern the sensitivity and selectivity of this system. When the gold electrode is modified with the mixture of GSH and 3-mercaptopropionic acid (3MPA), the resulting SAMs modified electrode shows better sensitivity and selectivity for Cu(II) compared with GSH SAM modified gold electrode. Under optimal conditions, the anodic wave height is linear to Cu(II) in the range of ca. 10 μM to 0.1 mM without preconcentration. The influence of various factors and related mechanism is discussed. The organic monolayer modified electrode is stable and simple to prepare.
Iron/copper promoted fragmentation reactions of .alpha.-alkoxy hydroperoxides. The conversion of octalins into fourteen-membered ring macrolides

Synthese de dimethoxy-6,10 decahydro oxacyclotetradecinnedione-2,7 a partir de dimethoxy-2,5 octahydronaphtalenepropanol-1 via l'action de Cu(OAc) 2 /FeSO 4 sur la dimethoxy-2,6 hydroperoxy-10 oxa-11 bicyclo [8.4. 0] tetradecanone-5
Role of Oxidized LDL in Atherosclerosis

Nowadays, Atherosclerosis is the most important source of morbidity and mortality in the world, and is detected by the accumulation of lipids deposits (mainly cholesterol) in macro‐ phages located not only in large but also in medium sized arteries. Currently, the association between atherosclerosis and heightened oxidative stress is widely accepted. Nevertheless, despite numerous efforts the role of oxidative stress in the progression of Atherosclerosis is still not clear. Oxidation is a biochemical process of loss of electrons, which is essential for life due to its involvement in the production of cellular energy. However, when oxidation is excessive causing cellular damage is when Oxidative Stress appears. This process is complex; therefore, it cannot be measured or defined by a single parameter. For this reason, currently the interest lies on developing antioxidant therapies and diets enriched with antioxidants that prevent or at least decrease cellular damage and atheromatous plaque formation originated by the excess of oxidative stress. Aim. The aim of this review is to analyze the state of the art on oxidized LDL role within the pathogenesis of atherosclerosis. This chapter will be developed according to the following titles, 1. Oxidative stress and atherosclerosis. 2. LDL Oxidation 3. OxLDL in atheromatous plaque formation 4. Study Models 5. OXIDATIVE STRESS AND ATHEROSCLEROSIS
DFT Study of a Novel Organic Film: The Structural versus Magnetic Effects

Unsaturated fatty acids have great interest by their activities as industrial materials in novel applications. In the present work, the cis-3-hexenoic acid (HA) adsorbed on the Ni(111) surface was studied by first-principles calculations using the Vienna Ab Initio Simulation Package (VASP). The most stable location for HA is presented on top site of Ni(111), although the energies are very similar for all the adsorption sites. The surface-molecule interaction takes place between the carboxyl group of HA and surrounding Ni atoms. The adsorption is weak and consequently the metal-molecule length is enhanced. The carboxyl group is elongated and weakened after adsorption giving rise to a shift in stretching frequencies. There are notable changes on the magnetic moments values of Ni surface atoms neighboring to the molecule that mainly induced magnetic moments on O and H atoms. Noticeable charge transfer occurs in 3d 4s, p Ni orbitals and 2s C, 2s p O, 1s H orbitals of carboxyl group. The surface presents positive work function changes after adsorption as a consequence of an electron back-donation. During interaction, the significance of the magnetic effects over the structural effects is evidenced. This sets the stage for a future adsorption process improvement based on the modification of the surface magnetic properties.
Mono-organotin(IV) and tin(IV) derivatives of 2-mercaptopyridine and 2-mercaptopyrimidine: X-ray structures of methyl-tris(2-pyridinethiolato)tin(IV) and phenyl-tris(2-pyridinethiolato)tin(IV)·1.5CHCl3

Mono-organotin(IV) and tin(IV) derivatives of 2-mercaptopyridine (HSPy) and 2-mercaptopyrimidine (HSPym), RSnL 3 (R=Me, n-Bu, Ph; L=SPy, SPym; R=Bz=benzyl, o-CIBz, oClC 6 H 4 , p-ClC 6 H 4 , o-tolyl, p-tolyl; L=SPy), RSnCIL 2 (R=Me, n-Bu, Ph; L=SPy, SPym), RSnCI 2 L (R=Me, n-Bu; L=SPy, SPym) and SnCI 4-n L n (L=SPy, SPym; n=2,4) were obtained from RSnCI 3 or SnCI 4 and NaL or by neutralization (R=Ph,p-tolyl; L=SPy, SPym). RSnCIL 2 and RSnCI 2 L were better prepared by comproportionation of RSnCI 3 and RSnL 3 . MeSn(Spy) 3 and PhSn(SPy) 3 . 1.5CHCI 3 crystals, as determined by single-crystal X-ray diffraction, are monoclinic. In the discrete monomeric RSn(SPy) 3 units, three bidentate SPy ligands together with R form a distorted pentagonal bipyramid around tin. One S and the C(R) atom are in the axial positions. Two S atoms and three N atoms form the pentagonal plane. From 119 Sn Mossbauer and IR data, analogous structures are inferred for the other solid RSnL 3 compounds, except for R=Bz, o-CIBz, o-CIC 6 H 4 and o-tolyl, in which tin would be hexacoordinated. In the compounds RSnCIL 2 and RSnCI 2 L, tin is at the center of an octahedron or a trigonal bipyramid, respectively. For Sn(SPym) 4 and SnCI 2 (SPym) 2 , the same type of octahedral structure as was previously found for Sn(Spy) 4 . HSPy and SnCI 2 (Spy) 2 is proposed. According to IR and 1 H, 13 C and 119 Sn NMR data, the solid-state molecular structures are retained in chloroform and dimethyl sulfoxide solution.
Chemiluminescence‐Generating Nanoreactor Formulation for Near‐Infrared Imaging of Hydrogen Peroxide and Glucose Level in vivo

Water‐dispersed all‐in‐one nanoprobes composed of densely integrated peroxyoxalate fuel and a cyanine dye are formulated to optimize the nanoscopic chemiluminescence reaction. It is demonstrated that the chemiluminescent nanoformulation can generate bright near‐infrared signal in response to external hydrogen peroxide that is biologically implicated with cell signaling and diseases. Successful imaging of endogenously overproduces hydrogen peroxide and indirect determination of glucose level in vivo with the chemiluminescent nanoprobes offers an opportunity for early diagnosis of diseases.