Solvation of magnesium chloride and sulfate in aqueous solutions at 278.15–323.15 K

Isoentropy compressibilities of aqueous magnesium chloride and sulfate were determined based on precision measurements of ultrasound velocity, density, and isobaric heat capacity at low to high concentrations at 278.15–323.15 K. The hydration numbers h and the molar parameters of volume and compressibility were calculated based on thermodynamically correct equations for hydration complexes (V _h , β _h V _h ), water in the hydration shell (V _1h , β_1h V _1h ), and the void containing a stoichiometric mixture of ions (V _2h , β_2h V _2h ). The h and β _h V _h values were found to be independent of temperature; the molar compressibility of the hydration sphere (β_1h V _1h ) and the stoichiometric mixture of ions without a hydration shell (β_2h V _2h ) were independent of the concentration under the stated conditions. The effect of the electrostatic field of ions on the temperature dependence of the molar volume of water in the hydration sphere was more significant than the effect of pressure on the temperature dependence of the molar volume of bulk water. This is attributed to changes in the dielectric constant of water in the vicinity of the electrolyte ions.     

Prostaglandin chemistry—IV : Microbiological kinetic resolution and asymmetric hydrolysis of 3,5-diacetoxycyclopent-1-ene

A 1:1 mixture of cis- and trans-3,5-diacetoxycyclopent-1-ene (1) was asymmetrically hydrolysed by baker's yeast to give trans-3(R)-acetoxy-5(R)-hydroxycyclopent-1-ene (R-2a) and S-predominant 3,5-dihydroxycyclopent-1-ene (3) accompanied by trans-3(R),5(R)-diacetoxycyclopent-1-ene (R-1a).The optical activities on the products were found to be dependent on the difference of the enzymatic hydrolytic rate among cis-, trans(S,S)- and trans(R,R)-3,5-diacetoxycyclopent-1-ene.The asymmetric hydrolysis was also investigated on wheat germ lipase, citrus acetyl esterase, and the lipase prepared from Aspergillus niger.     

Microcalorimetry coupled with principal component analysis for comparing the effects of two Panax species on mice splenic lymphocytes

A powerful microcalorimetric method based on the cell heat production was applied to evaluate the effects of two Panax species on mice splenic lymphocytes growth. Some qualitative and quantitative information, such as the metabolic power-time curves, growth rate constant k, maximum heat-output power P _max, appearance time for the highest peak t _max, total heat production Q _t for all the metabolic progress of mice splenic lymphocytes were obtained to present the effects of Panax ginseng and American Ginseng on these cells. Coupled with principal component analysis (PCA) on these quantitative thermokinetic parameters, the effects of the two Panax species on mice splenic lymphocytes could be quickly evaluated by analyzing the change of the main parameter k. From the values of k, it could be concluded quickly and accurately that Panax ginseng and American Ginseng both showed strong inhibitory effects on mice splenic lymphocytes, and the inhibitory effects was strengthened with increasing concentration of the two Panax species in the concentration range of 0–3.2 mg mL^?1. Panax ginseng with IC ₅₀ of 1.38 mg mL^?1 showed stronger inhibitory effect on mice splenic lymphocytes growth than American Ginseng with IC ₅₀ of 2.08 mg mL^?1. This study indicates that microcalorimetry is a powerful tool for evaluating the drugs’ efficiency on living system, providing some useful references for the application of Panax ginseng and American Ginseng in practice.     

Effect of blending way on β-crystallization tendency of compatibilized β-nucleated isotactic polypropylene/poly(ethylene terephthalate) blends

The main purpose of this study is to investigate the β-crystallization tendency in the β-nucleated iPP blends. The β-nucleated iPP/compatibilizers blends, β-nucleated iPP/PET blends and its compatibilized versions with four kinds of compatibilizers (PP-g-MA, PP-g-GMA, POE-g-MA, and EVA-g-MA) were prepared by different blending ways. The effect of compatibilizers and blending ways on the non-isothermal crystallization and melting characteristics and the β-crystallization tendency of β-nucleated iPP blends were studied by differential scanning calorimetry. The relative content of the β-phase were characterised by the k _β values determined on the basis of the wide angle X-ray diffractogram. The results indicated that the β-crystallization tendency of β-nucleated iPP blends depends on the kinds of compatibilizer. Addition of PP-g-MA significantly reduced the β-crystallization tendency of β-nucleated iPP, while PP-g-GMA, POE-g-MA, and EVA-g-MA have little effect on it. In the compatibilized β-nucleated iPP/PET blends, the blending ways, which controlled the dispersion of β-nucleating agent, influences the β-crystallization tendency intensively. The high β-crystallization tendency and β-crystal content were obtained for compatibilized β-nucleated iPP/PET blends prepared firstly at high temperature and β-nucleating agent added into blends at low temperature; however, the type of compatibilizers has little effect on β-crystallization tendency and melting behavior of blends.     

Effects of substrate and transfer on CVD-grown graphene over sapphire-induced Cu films

We differentiated the effects of Cu films deposited on single crystalline a-,r-,and c-plane sapphire substrates upon graphene films synthesized with atmospheric pressure chemical vapor deposition(CVD).The data illustrate that the realization of high-crystalline Cu film is dependent not only on the crystallinity of underlying substrate,but also on the symmetric match of crystallographic geometry between metal film and substrate.We also systematically investigated the effects of PMMA removal on the Raman ID/IG and IG/I2D values of transferred graphene.The results reveal that different PMMA removal methods do not alter the ID/IG values;instead,the residue of PMMA increases the IG/I2D values and the thermal decomposition of PMMA leads to higher IG/I2D values than the removal of PMMA with acetone.The effects of PMMA removal on variations of the Raman spectra are also discussed.     

Infrared band intensities: a comparative study of the transition moment matrix elements for the fundamental and overtones: Part II. Application to CO,HCl and OH

The various expressions considered in Part I for the transition moment matrix elements of fundamental and first two overtones are applied to carbon monoxide. The coefficients a_ij in the expressions R^io = Σa_ijp_j (where R^io is the transition moment integral for the O → i vibrational transition and p_j is the dipole moment derivative ?^jP/?XXX^j, XXX = (r — r_e)/r_e, r_e is equilibrium bond distance) are reported for i,j = 1, 2, 3. It is found that these coefficients do not vary by more than 5% when compared for the same i,j values in various expressions irrespective of the most exhaustive treatments used in deriving the original expressions. On the basis of the values of the coefficients obtained for CO, generalisations have been suggested on the effects of inclusion of mechanical and electrical anharmonicity to the intensities of fundamental and first two overtones. It is generally observed that the contribution of p'₁, is about 100 fold more than the contribution of p'₂, for R¹⁰. On the other hand the contributions of p'₁, and p, for R²⁰ and R³⁰ are of nearly equal magnitude but opposite in sign. The contribution of p'₁ to R¹⁰ is much higher than its contribution to R²⁰ and R²⁰. The various observations lead us to conclude that, whereas the effect of inclusion of mechanical anharmonicity on the intensity of the fundamental band is negligible, this effect is almost comparable to the effect of inclusion of electrical anharmonicity for the first two overtones. Simple forms of the a_ij expressions are applied to HC1 and OH to demonstrate the effect of variation of molecular constants on the a_ij values. On the basis of the observed trend in the values of these coefficients for CO, HCl and OH general remarks on the effects of hydrogen bonding on IR band intensities are given.     

Modulating Properties of Piroxicam,Meloxicam and Oxicam Analogues against Macrophage-Associated Chemokines in Colorectal Cancer

The mechanisms underlying the antineoplastic effects of oxicams have not been fully elucidated. We aimed to assess the effect of classic and novel oxicams on the expression/secretion of macrophage-associated chemokines (RTqPCR/Luminex xMAP) in colorectal adenocarcinoma cells, and on the expression of upstream the non-steroidal anti-inflammatory drug (NSAID)-activated genes NAG1, NFKBIA, MYD88, and RELA, as well as at the chemokine profiling in colorectal tumors. Meloxicam downregulated CCL4 9.9-fold, but otherwise the classic oxicams had a negligible/non-significant effect. Novel analogues with a thiazine ring substituted with arylpiperazine and benzoyl moieties significantly modulated chemokine expression to varying degree, upregulated NAG1 and NFKBIA, and downregulated MYD88. They inhibited CCL3 and CCL4, and their effect on CCL2 and CXCL2 depended on the dose and exposure. The propylene linker between thiazine and piperazine nitrogens and one arylpiperazine fluorine substituent characterized the most effective analogue. Only CCL19 and CXCL2 were not upregulated in tumors, nor was CXCL2 in tumor-adjacent tissue compared to normal mucosa. Compared to adjacent tissue, CCL4 and CXCL2 were upregulated, while CCL2, CCL8, and CCL19 were downregulated in tumors. Tumor CCL2 and CCL7 increased along with advancing T and CCL3, and CCL4 along with the N stage. The introduction of arylpiperazine and benzoyl moieties into the oxicam scaffold yields effective modulators of chemokine expression, which act by upregulating NAG1 and interfering with NF-κB signaling.     

Using Gas-Phase Guest–Host Chemistry to Probe the Structures of b Ions of Peptides

Middle-sized b _n (n????5) fragments of protonated peptides undergo selective complex formation with ammonia under experimental conditions typically used to probe hydrogen?Cdeuterium exchange in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Other usual peptide fragments like y, a, a*, etc., and small b _n (n????4) fragments do not form stable ammonia adducts. We propose that complex formation of b _n ions with ammonia is characteristic to macrocyclic isomers of these fragments. Experiments on a protonated cyclic peptide and N-terminal acetylated peptides fully support this hypothesis; the protonated cyclic peptide does form ammonia adducts while linear b _n ions of acetylated peptides do not undergo complexation. Density functional theory (DFT) calculations on the proton-bound dimers of all-Ala b ₄ , b ₅ , and b ₇ ions and ammonia indicate that the ionizing proton initially located on the peptide fragment transfers to ammonia upon adduct formation. The ammonium ion is then solvated by N⁺-H??O H-bonds; this stabilization is much stronger for macrocyclic b _n isomers due to the stable cage-like structure formed and entropy effects. The present study demonstrates that gas-phase guest?Chost chemistry can be used to selectively probe structural features (i.e., macrocyclic or linear) of fragments of protonated peptides. Stable ammonia adducts of b ₉ , b ₉ -A, and b ₉ -2A of A₈YA, and b ₁₃ of A₂₀YVFL are observed indicating that even these large b-type ions form macrocyclic structures.     

Elastic behavior of single polymer chains adsorbed on rough surfaces

In this paper, elastic behaviors of single polymer chains adsorbed on the rough surfaces with a substrate and some periodically tactic pillars are investigated by the pruned-enriched-Rosenbluth method (PERM). In our simulation, a single polymer chain is firstly adsorbed on the substrate and then pulled along the z-axis direction, which is vertical to the substrate. We investigate the chain size and shape of polymer chains, such as mean-square radii of gyration per bond 〈S²〉_xy/N, 〈S²〉_z/N and shape factor 〈δ^∗〉 in order to show how the size and shape of adsorbed polymer chains change during the desorption process. Due to the occurrences of separation of the chains from the substrate, farther adsorption on the upper surfaces of pillars and complete separation from the whole rough surfaces in the elastic process, the changes of 〈S²〉_xy/N, 〈S²〉_z/N and 〈δ^∗〉 during the process are complicated. On the other hand, some thermodynamic properties such as average energy per bond, average Helmholtz free energy per bond, elastic force f are investigated, and our aim is to study the elastic behaviors of polymer chains adsorbed on the rough surface during the elasticity process. Elastic force f has some plateaus during the desorption process for strong adsorption interaction. If there is no adsorption interaction, the chains can get away from the rough surfaces spontaneously. These investigations can provide some insights into the elastic behaviors of polymer chains adsorbed on the rough surface.     

Classification for molecular aggregation structure of monolayers on the water surface

The melting temperature, T_m, and the crystalline relaxation temperature, Tα_c, of palmitic acid and dipalmitoyl phosphatidylcholine monolayers on the water surface were evaluated by combination of two kinds of measurements: first, the subphase temperature, T_sp, dependence of the monolayer modulus based on the surface pressure-area (π-A) isotherm and second, the T_sp dependence of the electron diffraction, ED patterns of their monolayers. On the basis of their characteristic temperatures of the monolayers, the aggregation structure of the monolayers which were transferred onto a hydrophilic SiO substrate at various surface pressures and T_sps was investigated by means of transmission electron microscopy. The π-A isotherm for the fatty acid monolayer on the pure water surface represented the aggregating process of isolated domains grown right after spreading a solution on the pure water surface. The fatty acid monolayer on the pure water surface was classified into a crystalline monolayer (T_sp < T_m) and an amorphous one (T_sp > T_m). The crystalline monolayer was further classified into two types; crystalline domains were aligned along their crystallographic axes owing to an induced sintering at the interfacial region among monolayer domains by surface compression (T_sp < Tα_c), while not for T_sp > Tα_c. In the case of the phospholipid monolayer, the monolayer was classified into a compressing crystallized monolayer (T_sp < T_m) and an amorphous one (T_sp > T_m). The compressing crystallized monolayer is a monolayer in which crystallization was gradually induced at plateau region on the π-A isotherm by compression. Electron diffraction studies of arachidic acid monolayers in different dissociated states of hydrophilic groups revealed that formation of the compressing crystallized monolayer was attributed to an electrostatic repulsion among ionic hydrophilic groups. It was concluded that the aggregation structure of monolayers on the water surface was systematically classified into ‘the crystalline monolayer’, ‘the amorphous monolayer’ and ‘the compressing crystallized monolayer’, with respect to thermal and chemical (intermolecular repulsive) factors.     

Para-selectivity of SAPO-5 and mordenite catalysts in the alkylation of cumene with 2-propanol

Alkylation of cumene with 2-propanol was studied on SAPO-5 and mordenite catalysts. The primary products of the alkylation on every catalyst examined here were p- and m-diisopropylbenzene (DIPB) in a ratio of 75:25. The p-DIPB fraction in DIPB isomers (para-selectivity) decreased with increasing yield of DIPB, due to the secondary reaction of p-DIPB to m-DIPB. On SAPO-5, mordenite and silica-alumina, this secondary reaction proceeds through dealkylation of p-DIPB to cumene, followed by re-alkylation of the resultant cumene to m-DIPB. The dealkylation of p-DIPB would occur preferentially over that of m-DIPB. This was due to the higher reactivity of p-DIPB and probably to the reactant molecular shape selectivity of SAPO-5 and mordenite. The para-selectivity was improved by supporting boron oxide on SAPO-5 and mordenite; this improvement was caused by suppression of the secondary dealkylation of p-DIPB.     

Recurrence calculations of organic compound boiling temperatures from data on preceding homologues

A new approach to calculating the temperatures of boiling at atmospheric pressure (T _b) of organic compounds from arbitrary homologous series is suggested. The approach is based on the linear dependence of these values on T _b for the preceding homologues, T _b(n) = aT_b(n ? 1) + b. This dependence, revealed for the first time, was used to obtain a recurrence relation for calculating T _b of organic compounds within any series from the data on three simpler homologues of the same series. The mean a and b values can be used to estimate T _b of an arbitrary organic compound from T _b for one preceding homologue with an accuracy not inferior to that provided by the modern ACD software. Correlations of the general form P(n) = aP(n ? 1) + b are observed not only for the boiling points of organic compounds but also for their other properties P (refractive indexes, relative densities, and ionization energies). This opens up the possibility of creating unified algorithms for calculating various physicochemical constants of organic compounds instead of particular algorithms for every particular property known earlier.     

Characterisation of electron transport and back reaction in dye-sensitised nanocrystalline solar cells by small amplitude laser pulse excitation

The characterisation of the transport and interfacial reaction of electrons in dye-sensitised nanocrystalline solar cells is complicated by the non-linearity of these processes. This problem has been overcome by superimposing small amplitude pulsed laser excitation on steady background illumination. The laser perturbation of the photostationary state is sufficiently small that the photocurrent and photovoltage responses can be fitted using constant values of the electron diffusion coefficient D_n and electron lifetime τ_n. Analytical and finite difference solutions of the continuity equation have been used to analyse the experimental photocurrent, photocharge and photovoltage transients, and the intensity dependence of D_n and of τ_n has been established by varying the bias illumination level, and hence the dc photocurrent density, j_dc. The intensity dependence of D_n (D_n∝j_dc^0.68) is attributed to trapping/detrapping involving a distribution of trapping levels. The intensity dependence of τ_n (τ_n∝j_dc^−0.62) may indicate that the back reaction of electrons with I₃⁻ is not first order in electron concentration. Other possible explanations are that the interfacial electron transfer rate constant depends on trap occupancy or on the rate of surface or bulk electron diffusion.     

Structural study of lanthanum nickelate thin films deposited on different single crystal substrates

Fabrications of La₂NiO_4+δ thin film layers by liquid-injection metalorganic chemical vapor deposition were tried on different single crystals substrates: (001)Si, (001)MgO, (001)LaAlO₃ and (001)SrTiO₃. As results of structural characterizations, polycrystalline dendritic layers of La₂NiO_4+δ tetragonal (or orthorhombic) phase were observed on (001)Si substrates while layers of a perovskite-like cubic structure were observed on the other single crystal substrates. From a high-resolution TEM study of a layer deposited on (001)MgO, such a perovskite-like cubic structure exhibits many planar structural faults likely similar to planes of oxygen vacancies of the La₂NiO_4+δ orthorhombic structure. A thin intermediate epitaxial layer of NiO phase was also identified. Using a X-ray texture diffractometer, the layer structure on (001)MgO, (001)LaAlO₃ and (001)SrTiO₃ was confirmed to be of cubic structure with 〈100〉 axes parallel to those of the substrate. The T dependence of the resistivity of a layer deposited on (001)MgO substrate was found to be of a semi-conducting behavior.     

Influence of the polyether chain on the dissociation of “living” polymers obtained in the anionic polymerization of ethylene oxide

Conductivity studies were carried out on block copolymers of composition K⁺, ?(EO)_n- αMeSt-(St)_x -αMeSt-(EO)_n^?, K⁺, where n = 1–5 or 20, in THF. The conductivity of the solutions exhibits a strong tendency to increase as n is raised up to 3, and to change only slightly on further extension of the polyether chain. An equilibrium between ion pairs and free ions is established in the solution only when n is 1 or 2; for n ? 3, ion triplets are formed also. The dissociation constants for the ion pairs and the ion triplets and their temperature dependence were determined. The formation of ion triplets, as well as the changes in dissociation of the ion species on extending the polyether block, are explained by solvation of the counter-ion by the polyether chain.     

Alternating melting points,heats and entropies of fusion of linear aliphatic polyesters

Heats of fusion of polyethylene-adipate, pimelate, suberate and azelaate have been determined by two methods, viz. DTA and the pressure dependence of the melting point up to 6000 bar. Degrees of crystallization were measured dilatometrically. Entropies of fusion were divided into volume and conformational entropy terms, only the latter alternates. Alternation of melting points depends on enthalpy of fusion ΔH_m, entropy of fusion ΔS_m and volume change Δυ on melting; influence of the functions increases thus ΔV_m < ΔH_m < ΔS_m and ΔS_m is dominant. Entropy and heat of fusion alternation is explained by the conformational change on melting governed by the driving force of maximum H-bridge formation.     

Quantitative characteristics of hydration in solutions of sodium sulfate and sodium chloride at 278.15–323.15 K

The solvation parameters of aqueous solutions of sodium chloride and sodium sulfate were studied on the basis of published density and ultrasound velocity data. Correct thermodynamic relations for temperature variation from 278.15 to 323.15 were used to determine quantitative parameters of solvation, in particular, the hydration numbers h, the molar adiabatic compressibility of hydrate structures β _h V _h , the volume V _1h and compressibility β _1h of water in the hydration shells of ions, and others. h and β _h V _h do not depend on temperature in the range of parameters studied, and electrostriction compression about the ions has a more pronounced effect on the structure than mere pressure change.     

Microcalorimetric investigation on antibacterial activity of the peptide from Plutella xylostella

The antibacterial activities of a kind of novel peptide from Plutella xylostella (pxCECA1) on methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E. coli) growth were investigated by microcalorimetry. The heat flow power–time curves of MRSA and E. coli growth in the presence of pxCECA1 were recorded using the 3114/3115 Thermal Activity Monitor Air Isothermal Calorimeter based on ampoule mode at 37 °C. Some parameters including growth rate constant k, maximum power output P _max, total heat output Q_t, generation time t _g, growth inhibitory ratio I, and half-inhibitory concentration of the drugs IC₅₀ were obtained to elucidate the antibacterial activity of pxCECA1. The results showed that k, P _max, and Q _t decreased, but I and t _g increased or delayed with the increase in pxCECA1 concentration. The IC₅₀ of pxCECA1 on E. coli was 6.122 μg mL^?1 and MRSA was 7.809 μg mL^?1. It could be concluded that pxCECA1 had stronger inhibitory effect on E. coli than MRSA. In vivo test was simultaneously performed using an E. coli and MRSA infection model to validate the antibacterial activity of pxCECA1. The results revealed that pxCECA1 with broad spectrum antimicrobial activities hopefully represented a class of promising substitute of antimicrobial agents.     

Static contact angle hysteresis on smooth, homogeneous solid substrates

A theory of contact angle hysteresis on smooth, homogeneous solid substrates is developed in terms of shape of disjoining/conjoining pressure isotherm and quasi-equilibrium phenomena. It is shown that all contact angles, θ, in the range θ _r?<?θ?<?θ _a, which are different from the unique equilibrium contact angle θ?≠?θ _e, correspond to the state of slow “microscopic” advancing or receding motion of the liquid if θ _e ?<?θ?<?θ _a or θ _r?<?θ?<?θ _e, respectively. This “microscopic” motion almost abruptly becomes fast “macroscopic” advancing or receding motion after the contact angle reaches the critical values θ?=?θ _a or θ _r?=?θ, correspondingly. The values of the static receding, θ _r, and static advancing, θ _a, contact angles in cylindrical capillaries were calculated earlier, based on the shape of disjoining pressure isotherm. It is shown that an advancing contact angle of a droplet on a solid substrate depends on the drop volume and is not a unique characteristic of the liquid–solid system. The suggested mechanism of contact angle hysteresis has direct experimental confirmation.