Phase transitions and positive definite couplings

The method of infrared bounds is extended to a large class of nearest neighbour interactions in classical spin systems. Temperature controlled bounds on fluctuations follow whenever the coupling function is a positive definite kernel. Existence of phase transitions is demonstrated for the RP ^Nmodel for d3.     

5-isobutyl-3-methyl-2-furancarbaldehyde,a new monoterpenoid from the essential oil of tagetes glandulifera schrank

The new monoterpenoid 5-isobutyl-3-methyl-2-furancarbaldehyde was isolated from Tagetes glandulifera Schrank and its structure confirmed by synthesis.     

New designer drug 1-(3-trifluoromethylphenyl) piperazine (TFMPP): gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry studies on its phase I and II metabolism and on its toxicological detection in rat urine

Studies are described on the phase I and II metabolism and the toxicological analysis of the piperazine-derived designer drug 1-(3-trifluoromethylphenyl)piperazine (TFMPP) in rat urine using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). The identified metabolites indicated that TFMPP was extensively metabolized, mainly by hydroxylation of the aromatic ring and by degradation of the piperazine moiety to N-(3-trifluoromethylphenyl)ethylenediamine, N-(hydroxy-3-trifluoromethylphenyl)ethylenediamine, 3-trifluoromethylaniline, and hydroxy-3-trifluoromethylaniline. Phase II reactions included glucuronidation, sulfatation and acetylation of phase I metabolites. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction and microwave-assisted acetylation allowed the detection of TFMPP and its above-mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of TFMPP in human urine.     

High pressure inactivation of Clostridium botulinum type E endospores in model emulsion systems

Clostridium botulinum type E is a cold-tolerant, neurotoxigenic, endospore-forming organism, primarily associated with aquatic environments. High pressure thermal (HPT) processing presents a promising tool to enhance food safety and stability. The effect of fat on HPT inactivation of C. botulinum type E spores was investigated using an emulsion model system. The distribution of spores in oil-in-water (O/W) emulsions and their HPT (300–750?MPa, 45–75?°C, 10?min) inactivation was determined as a function of emulsion fat content (30–70% (v/v) soybean oil in buffer). Approximately 26% and 74% of the spores were located at the oil–buffer interface and the continuous phase, respectively. Spore inactivation in emulsion systems decreased with increasing oil contents, which suggests that the fat content of food plays an important role in the protection of C. botulinum type E endospores against HPT treatments. These results can be helpful for future safety considerations.     

Frequency and temperature dependence of molecular and micromechanical transitions in PPO/PMMA/P(S-g-EO) blends

The frequency and temperature dependence of molecular and micromechanical transitions were studied in polymer blends with an interphase. The viscoelastic properties of poly(2,6-dimethyl-p-phenylene oxide) (PPO) and poly(methyl methacrylate) (PMMA) blends that were compatibilized by a poly(styrene-graft-ethylene oxide) (P(S-g-EO)) copolymer were studied by dynamic mechanical spectroscopy (DMS) and the experimental data were compared with an interlayer model. The addition of the copolymer resulted in a micromechanical transition, and the relation between the volume fraction of interphase, the activation energy of the micromechanical transition, and the micromechanical transition temperature was studied. A qualitative agreement between experiments and theory was achieved. The quantitative difference was explained by partial mixing of PPO and/or PMMA with the copolymer in the interphase. © 1996 John Wiley & Sons, Inc.     

The Application of Heat Treatment in the Formation of Relief-Phase Holographic Structures on Dichromed Gelatin

Optics and Spectroscopy - A new method of formation of relief-phase holographic structure on dichromated gelatin (DCG) layers has been proposed. The method is based on two types of alternative...     

Effect of Sulfation Route and Subsequent Oxidation on Derivatization Degree and Biocompatibility of Cellulose Sulfates

Sulfated cellulose (CS) represents an interesting biopolymer due to bioactivity comparable to heparin. However, use of CS for making surface coatings or hydrogels requires the presence of reactive groups for covalent reactions. Here, an approach is presented to oxidize cellulose sulfates for subsequent cross‐linking reactions with amino groups to form imine bonds. Cellulose is sulfated by direct sulfation or acetosulfation, followed by a M alaprade oxidation. The CS obtained is characterized by elemental analysis and ¹³C‐NMR spectroscopy. The resulting oxidized cellulose sulfates (oxCS) have different degrees of sulfation ranging from 0.79 to 1.13 and oxidation degrees from 0.18 to 0.34, but also different mass average molecular mass (M_W). Toxicity studies are carried out with mouse 3T3 fibroblasts exposed to aqueous solutions of oxCS. The results show that all oxCS are non‐toxic at lower concentrations (0.5 mg mL^?1), but with both increasing degree of oxidation and concentrations, toxic effects are observed particularly for acetosulfated and lesser for direct sulfated oxCS, which is related to a decrease in the M_W of the products. It is concluded that oxCS obtained by direct sulfation with M_W above 70 kDa may represent a biocompatible material for the applications suggested above.     

Optical pulse broadening in long fibre waveguides

As a result of research, the propagation characteristics of optical waveguides are becoming well enough understood for system evaluation. In this paper material and structural properties of the waveguide are related to measurements made on present experimental waveguides. Among the conclusions drawn from this work are that intermodal dispersion provides the dominant pulse broadening contribution but that this has been reduced to the nanosecond region by radial index gradient control. For present source spectral bandwidths, material dispersion is not a major contribution to pulse broadening. Waveguides up to 3 km long can be made with negligible intrinsic mode coupling. This gives rise to the possibility of either internal or external control to increase the information carrying capacity of the waveguide. External control has already been demonstrated. However, additional work is required to make this practical.