Equation of state for hydrofluorocarbon refrigerant mixtures of HFC-125/143a,HFC-125/134a,HFC-134a/143a and HFC-125/134a/143a

Equations of state (EOSs) in the form of dimensionless Helmholtz free energy have been developed for the binary hydrofluorocarbon (HFC) refrigerant mixtures HFC-125/143a, HFC-125/134a, HFC-134a/143a and for the ternary refrigerant mixture HFC-125/134a/143a in the present work. These EOSs are effective in the temperature and pressure ranges where the experimental measurements covered, i.e., 200 K⩽T⩽413 K, P⩽35 MPa for HFC-125/143a and HFC-125/134a; 243 K⩽T⩽413 K, P⩽17 MPa for HFC-134a/143a and HFC-125/134a/143a. Experimental measurements in both single-phase and two-phase regions are represented by the present EOSs within their estimated uncertainties.     

Construction of a novel Mo/Cu/S cluster with a closed double-cubane-like polyhedron and a chain polymer of W/Cu/S clusters

Reaction of [MoOS(3)](2)(-) and [WS(4)](2)(-) with Cudtp (dtp = diethyl dithiophosphate) gave rise to the clusters [Bu(4)N](2)[(MoOS(3))(4)Cu(12)(dtp)(6)], 1, and [Et(4)N][(WS(4)Cu(4))(dtp)(3)], 2, respectively. In cluster 1, the dtp- ligands act as both monodentate and bidentate ligands that bridge between Cu atoms and link together a closed double-cubane-like [Mo(2)O(2)S(6)Cu(6)](2+) core and two incomplete cubane-like [MoOS(3)Cu(3)]+ units. In cluster 2, the [WS(4)Cu(4)](2+) fragments were connected via bidentate and doubly bridging dtp- bridges to give a chain polymeric anion. Cluster 1 is the first example of a Mo/Cu/S cluster that contains a closed double-cubane-like structure. Compound 2 is also rare and the first W/Cu/S polymer with dtp- linkages.     

I/V characteristics of a molecular switch

We present a study of the conduction properties of a class of aromatic compounds, whose conformation can be modulated with a transverse electric field, with strong effects on the molecular transport properties. The theoretical method includes the molecule–electrode interaction in a simple, although effective way: the coupling matrix elements are considered independent from the energy of the continuum spectrum of the lead. This results in a simple expression for the molecular Green’s function with a significant simplification in the expression of the transmission function. The effects of the voltage bias on the electronic molecular density is included through a uniform effective electric field. A simplified but accurate method for the evaluation of the molecular response to the field, which spares lengthy computations for each value of the voltage, is presented. The proposed method is calibrated on the widely studied benzene-1,4-dithiol molecule. The calculations on the selected molecular wire (a tetracyano derivative of 4,4′-di(mercaptoethynyl)tolan) show that conductivity is low for perpendicular rings, whereas conduction is allowed for the planar conformation, which corresponds to the equilibrium geometry in the absence of the transverse electric field.     

Salvifarinin A,a neo-clerodane diterpenoid with a 6/5/7 tricyclic skeleton from Salvia farinacea

Salvifarinin A (1), a rearrangement product of Languidulane-type clerodane diterpenoids with a 6/5/7 tricyclic ring skeleton fused with γ-lactone ring and furan ring, and two new biogenetically related diterpernoids, salvifarinins B (2) and C (3), were isolated from the aerial parts of Salvia farinacea. The absolute configuration of 1 was elucidated by extensive spectroscopic methods, and confirmed by single crystal X-ray diffraction and bio-inspired semisynthesis. The plausible biogenetic pathway was also proposed. Compound 2 displayed a potent effect on reducing hepatic steatosis.     

Conversion of a trans-syn-trans to a cis-syn-trans perhydrobenz[e]indenone triggered by intramolecular 1,5-hydrogen transfer

The conversion of a trans-syn-trans perhydroiodomethyltrimethylbenz[e]indenone to the corresponding cis-syn-trans perhydrobenz[e]indenone occurred during the reduction of the iodomethyl to a methyl group under radical conditions.     

Evaporation/Precipitation from a W/O Microemulsion Base

The evaporation path in a microemulsion base of water, sodium dodecylsulfate, and pentanol was extended to include the subsequent precipitation stage caused by the restriction of the surfactant solubility. The results revealed the surfactant to be the only compound to precipitate during the evaporation/precipitation stage; the relative content of the two volatile compounds in the liquid phase was adjusted to the required level by the evaporation.     

PB/Au/CILE的制备与应用

混合离子液体(N-丁基吡啶六氟磷酸盐,[BuPy][PF6])与石墨粉,制备了离子液体碳糊电极(CILE),再采用电沉积法制得PB/Au/CILE修饰电极,研究了该修饰电极的电化学行为及其对H2O2的电催化,建立了H2O2的计时安培测定新方法。结果表明:在该修饰电极上PB产生了一对准可逆的氧化还原峰,并对H2O2表现出良好电催化作用,安培法测定H2O2的线性范围为5.0×10-6～1.55×10-4mol/L,检出限为1.0×10-6mol/L(S/N=3)。连续10次测定5.0×10-6mol/L H2O2峰电流的RSD为2.1%。     

Structure of salvigenolide,a novel diterpenoid with a rearranged neo-clerodane skeleton from salviafulgens

From the aerial parts of Salvia fulgens Cav. (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This novel compound named salvigenolide, showed a six-seven A/B ring system with a trans fussion. A probable biogenetic route is proposed. Its structure and relative stereochemistry as in $\text{1}$, were established by spectroscopic means and X-ray diffraction analysis.     

PAHs Formation in the Depositions in a Methyl tert-Butyl Ether/Ar,a Methyl tert-Butyl Ether/O2/Ar and a Methyl tert-Butyl Ether/H2/Ar RF Plasma Environment

Contents and distributions of polycyclic aromatic hydrocarbons (PAHs) in the depositions were investigated and discussed in a MTBE/Ar, a MTBE/O₂/Ar and a MTBE/H₂/Ar plasma systems. A radio-frequency (RF) plasma system was used to produce the depositions under the designed operational condition. The identification and quantification of PAHs was accomplished by using a GC with a mass selectivity detector (GC/MS). Results indicated that when the input power controlled at high wattage (70 W) in the three systems, the contents of total-PAH in the MTBE/Ar system are higher than those of total-PAH in other system with adding O₂ or H₂. The comparison of three systems indicated the formation and accumulation of PAHs in the MTBE/Ar system is easier than other systems. At high input power wattage, when the MTBE/Ar mixture added O₂ or H₂, the domain pattern was shifted from both 3- and 4-ring PAH to 2-ring PAH. As far as the total-PAH content is concerned, the MTBE/Ar system at 70 W was found to have the highest mean total-PAH content (1540 g/g), while the MTBE/O₂/Ar system at 20 W had the lowest mean total-PAH content (44.4 g/g).     

AM/AA/APEG/NANB共聚物的合成与性能研究

通过丙烯酰胺(AM),丙烯酸(AA),烯丙醇聚氧乙烯醚(APEG)和N,N-二烯丙基苄胺(NANB)制备共聚物P(AM/AA/APEG/NANB)。确定了最佳反应条件:m(AM)∶m(AA)=6.5∶3,APEG为5 wt%,NANB加量0.2 wt%,pH为7,反应温度40℃,引发剂0.4 wt%。通过IR和1H NMR确定了聚合物的分子结构,并对其进行性能测试。结果表明:2000 mg·L-1的AM/AA/APEG/NANB溶液具有较好的流变性能(120℃,粘度保留率:38.56%;1000 s-1,粘度保留率:17.93%)和抗盐性能(20 000 mg·L-1Na Cl,2000 mg·L-1Mg Cl2或Ca Cl2,粘度保留率分别为22.14%、18.34%和15.33%),且提高采收率可达16.12%。     

Examination of a portable99Mo/99mTc isotope generator /SUBLITECHR/

Three SUBLITECH^R technetium generators were milked and generator products were tested for 5 d. Radionuclidic and radiochemical purity, pH of sodium pertechnetate solutions were -emitting impurities and pirogenity were not carried out. We can summarize that generators were running efficiently during our test period and in all cases the pertechnetate produced met the requirements of the European Pharmacopoeia.     

Mechanical characterization of a new Kevlar/Flax/epoxy hybrid composite in a sandwich structure

Natural fibers are inexpensive, biodegradable, and have similar specific properties to some synthetic fibers. Hardly any previous investigations exist of a composite made of multiple layers of pure Kevlar fiber fabric and pure Flax fiber fabric in a “sandwich structure”, but it only measured impact properties. The composite was made of 12 Flax/epoxy layers at the core in 3 possible configurations (i.e. [0]_12F, [0/90]_6F, or [±45]_6F) that were sandwiched by 2 Kevlar/epoxy layers (i.e. plain weave) on each side. This study showed maximum change in the mechanical properties with respect to Flax/Epoxy for tension (+137.85% in E_T, and +171.22% in σ_UT), compression (+171.22% in E_c, and −10.6% in σ_UC), 3-point bending (−11.54% in E_B, and +2.19 in σ_UB), torsion (−5.31% in G, and 395.82% in τ), and water absorption (60.04%). This novel hybrid composite may be useful for research and industry applications.     

Dy2O3 as a catalyst for a Meerwein-Ponndorf-Verley reaction

Dy₂O₃ activated at high temperature is reported as a catalyst for the liquid phase reduction of cyclohexanone. The catalytic activity of Dy₂O₃ activated at 300, 500 and 800°C and its mixed oxides with alumina for the reduction of cyclohexanone with 2-propanol has been reported. The data have been correlated with the electron donating properties of the catalysts which were reported from the adsorption of electron acceptors [EA] of various electron affinity on the surface of these oxides.     

N-Bromosuccinimide-dibenzoyl peroxide/azabisisobutyronitrile: a reagent for Z- to E-alkene isomerization

N-Bromosuccinimide-dibenzoyl peroxide/azobisisobutyronitrile is used to carry out several types of Z- to E-alkene isomerizations. The NBS-bromination conditions are sufficient for both allylic bromination and alkene isomerization. When the allylic hydrogens are not available in substrates, only the isomerization of the alkene takes place. The present conditions for isomerization of carbon-carbon double bonds are mild and efficient.     

Effects of Nonpolar and Polar Solvents on the Qx and QY Energies of Bacteriochlorophyll a and Bacteriopheophytin a

The effects of nonpolar and polar solvents on the Q_x and Q_y energies of bacteriochlorophyll (BChl) a and bacteriopheophytin (BPhe) a were examined by electronic absorption spectroscopy. All of the four different energies exhibited a linear dependence on R(n) = (n² - l)/(n²+ 2), where n is the refractive index of the solvent, in both nonpolar and polar solvents. The energy of each state of both pigments could be expressed as v = -dR(n) + e (in cm^-1) where coefficient d was related to the dispersive interaction between the solute and the solvent molecules. A theory developed by Nagae showed that coefficient d originates from the quantum-mechanical fluctuation of the multipole moments of the solute, in terms of which the following characteristics of the observed d values were explained: (1) In all of the four cases of the Q_x, and Q_y energies of both BChl a and BPhe a, the d values for the polar solvents were smaller than those for the non-polar solvents. (2) In both nonpolar and polar solvents, the d value of BChl a was larger than that of BPhe a in the Q_y energy, whereas the d value of BPhe a was larger than that of BChl a in the Q_x energy. (3) The d value of the Q_x energy was larger than that of the Q_y, energy for either case of BChl a or BPhe a.     

Mutual interactions in a ternary protein/bioprotectant/water system

The dynamics of hydration water play a key role in many biological processes. The activity and function of proteins are strongly affected by the presence of water, which interacts primarily by means of hydrogen bonding. These interactions are examined in this work by a comparison of neutron vibrational spectra (Inelastic Neutron Scattering, INS) of dry lysozyme and hydrated lysozyme at h = 0.7 (g of H₂O/g of protein) with those of a lysozyme/water mixture at the same hydration value in the presence of the glass-forming bioprotectant trehalose. A difference spectrum, obtained by subtracting the dry lysozyme spectrum from that of the lysozyme/water mixture, yields the hydration water spectrum which is compared to the INS spectra of different kinds of ice in order to determine the changes induced by lysozyme on the hydrogen-bonded network of water. An additional comparison is performed by using a double-difference spectrum obtained by subtracting both the dry lysozyme and the trehalose spectra from the lysozyme/trehalose/water ternary spectrum. The effects of the mutual interactions among the three components, i.e. protein, disaccharide and water, are determined by comparison of the spectra of the dry systems (lysozyme, trehalose) with the difference spectra obtained from subtraction of the dry systems from the binary systems. It is concluded that the interfacial water more strongly affects the intermolecular mode region at low frequencies, whereas the vibrational spectra at high frequencies are more influenced by lysozyme and trehalose.     

Gable-porphyrin as a cytochrome-c3 model

Cytochromec₃ has two quite different heme-heme interaction models, “gable”-type and “twist”-type. Bis m-(meso-triphenylporphinyl) benzene was newly prepared as a gable conformation model. This “gable” porphyrin exhibited moderate porphyrin-porphyrin and heme-heme interaction.     

Droplet Growth Dynamics in a Water/Oil/Surfactant System

We have studied the droplet growth dynamics in a water-oil-surfactant system, using the cell dynamics system simulations based on the time-dependent Ginzburg-Landau model with two order parameters. Our simulations are carried out in a two-dimensional system of uneven composition of water and oil. For various average surfactant concentrations, the spatial patterns and their time evolution are obtained. The Ostwald ripening behaviors in the sparse regime of the droplet distributions are obtained. Numerical simulations are also extended to the dense regime so that the interactions between the droplet domains cannot be neglected. In such a system, the dynamics of pattern formation become significantly slow as the average surfactant concentration increases and we cannot apply the familiar scaling law in this case. Copyright 2001 Academic Press.