Interactions between inorganic pigments and rabbit skin glue in reference paint reconstructions

Journal of Thermal Analysis and Calorimetry - The thermal degradation of rabbit skin glue, a collagen-based proteinaceous material used as a paint binder in paintings, was investigated in this...     

Effect of temperature on self-assembly of an ionic tetrapeptide

The self-aggregation of the ionic tetrapeptide RWDW (R = arginine, W = tryptophan, D = aspartic acid) was studied at three temperatures (15, 25 and 35 °C) by different experimental techniques such as atomic force microscopy (AFM), isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). AFM was used to investigate the morphology of the aggregates; the AFM images at 15 °C showed the presence of a dense network of entangled fibres, while at 35 °C the peptide assembled into sparse globular and fibrillar structures. Moreover, the calorimetric experiments showed that in all cases the disaggregation process is endothermic and dependent on the investigated temperature. Both the enthalpy of disaggregation and the cac change with temperature. In particular, at 35 °C, we obtained the lower enthalpy of disaggregation and higher cac, showing that the disaggregation process is favoured at high temperature. The DSC scans strengthen the hypothesis that the RWDW aggregation is a rather complex phenomenon.     

THE SYNTHESIS OF NEW POLED CROSSLINKED POLYMETHACRYLATES AND THEIR SECOND ORDER NONLINEAR OPTICAL PROPERTIES

Films were prepared from mixtures of copolymers of 4-nitro-4'- [N- methylacryloyloxyethyl,N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) andcopolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophorecontent: 25 mol %). During thermal poling process the anhydride reacts with the epoxygroup and the resulting crosslinked network structure will stabilize the second harmonicgeneration in the poled film. The second harmonic generation of the poled film shows amaximum with the variation of composition, this is presumed to be due to the effects of theincreasing of concentration, orientation order as well as orientation stability of chromophoregroups during crosslinking.     

An experimental investigation of cold storage in an encapsulated thermal storage tank

This paper experimentally investigates the thermal performance and the pressure drop of an encapsulated thermal storage tank during the charging process. A polyvinyl chloride (PVC) hollow cylinder is used as the thermal storage tank. The cylindrical capsules inside the thermal storage tank utilize water added with nucleation agents as the phase change material (PCM), and the coolant is the aqueous solution of ethylene glycol. A series of experiments were carried out to investigate the effects of the inlet coolant temperature and coolant flow rate on nucleation of capsules, heat transfer and pressure drop of the tank. The results indicate that cool energy can be fully stored in the form of latent heat when the inlet coolant temperature is set below the temperature with 100% nucleation probability. The lower the inlet coolant temperature and the larger the coolant flow rate, the more efficient the storage tank. A correlation for the pressure drop of coolant during a charging process is also developed.     

Novel Approach to Fabricate Carbon Molecular‐Sieve Membranes Based on Consideration of Interpenetrating Networks

Summary: Carbon molecular‐sieve membranes (CMSMs) have shown great potential for gas separation. They exhibit high selectivity by permitting effective size‐ and shape‐separation between gas molecules of similar molecular dimensions. Hence, the control of their pore size is very important. While previous studies have focused on the conditions of pyrolysis and its effect on CMSM properties, a novel approach is reported here whereby the precursor polymer is chemically modified prior to pyrolysis and the resultant CMSM was investigated for its gas separation properties. Pyrolysis of chemically crosslinked and uncrosslinked Matrimid® resulted in a change in d‐spacing from 5.6 to 3.6 and 3.7 Å, respectively. The crosslinked CMSM also exhibited greater ordering in its packing. The Matrimid‐derived CMSMs exhibited excellent separation properties for CO₂/CH₄.

Mechanism of chemical crosslinking modification.     

Quantification of total petrol hydrocarbons (TPH) in soil by IR-spectrometry and gas chromatography – conclusions from three proficiency testing rounds

Due to the utilisation of 1,1,2-trichlorotrifluoroethane (CFE) as extraction solvent the IR-spectrometric determination of total petrol hydrocarbon (TPH) in soil according to ISO/TR 11046 has been replaced by gas chromatography/flame ionisation detection (GC/FID) after extraction with a halogen-free solvent according to ISO/DIS 16703:2001. The results obtained with both methods by field laboratories in three proficiency testing (PT) rounds are compared. The consensus means obtained with GC/FID are typically 10%–20% (ranging between 0% and 25%) higher than those found with IR-spectroscopy. On the contrary, coefficients of variation (CV) are roughly double in case of GC/FID and are briefly discussed against the background of the Horwitz equation. Received: 19 November 2001 Accepted: 17 March 2002     

两片型f.θ透镜设计

设计一种两片型ｆ·θ透镜，结构简单，畸变误差小于０．０８６％；并简述设计这种简单透镜的方法和应考虑的问题。     

2+2] Cycloaddition of ketenes with ynamides. A general method for the synthesis of 3-aminocyclobutenone derivatives

Ynamides react with ketenes in [2+2] cycloadditions leading to a variety of substituted 3-aminocyclobut-2-en-1-ones. The ynamides employed in these reactions are readily available via the copper-promoted N-alkynylation of carbamates and sulfonamides with alkynyl bromides and iodides. The scope of the [2+2] cycloaddition with regard to both the ketene and ynamide component is described.     

The effect of orientation on the radiation induced degradation of polymers

A study has been made of the effect of orientation on the oxidative degradation of poly(vinylchloride) (PVC), low density polyethylene (LDPE) and high density polyethylene (HDPE) under the influence of γ- and u.v.-radiation. The effect of drawing in PVC is to increase the rate of oxidative degradation; in LDPE and HDPE, this rate decreases (especially for HDPE) both under u.v. and γ-radiation.     

Isothermal vapor-liquid equilibria of mixtures containing organic compounds. Part 5: Excess Gibbs energies of dichloromethane or chlorobutane + linear ether or acetal mixtures at 25°C1

Vapor-liquid equilibria for dichloromethane or chlorobutane+a linear mono-, or diether (diethyl ether, dipropyl ether, methyl butyl ether, 1,2-dimethoxyethane,) or an acetal (diethoxymethane), were determined at 25°C by head-space gas chromatographic analysis of the vapor phase directly withdrawn from an equilibration apparatus. Excess Gibbs energies, G ^E , activity coefficients at infinite dilution, f _i ^o as well as free energy of solvation, G ^o , were evaluated for all the systems. A tentative approach is presented based either on an additivity scheme of surface interactions and scaled particle theory to calculate group contribution to the free energy of solvation.Communicated at the Festsymposium celebrating Dr. Henry V. Kehiaian's 60^th birthday, Clermont-Ferrand, France, 17–18 May 1990