Sensory and compositional attributes of melting‐ and non‐melting‐flesh peaches for the fresh market

A study was conducted to determine differences in sensory and compositional characteristics of melting‐flesh (MF) and non‐melting flesh (NMF) fresh market peach genotypes. Sensory results showed that the NMF fruit (‘Oro A’ and FL 86‐28C) were ‘harder’, less ‘juicy’ and more ‘rubbery’ than their MF (FL 90‐20 and ‘TropicBeauty’) counterparts. A principal component analysis of the sensory data showed a clear distinction between the textural aspects of MF and NMF fruit, but not between their flavour aspects. Likewise, chemical analysis showed that while differences in pH, titratable acidity, and soluble solids were detected among the four genotypes, no consistent grouping could be made based on the MF/NMF nature of the fruit. © 1999 Society of Chemical Industry     

The effect of phospholipids and water on the isothermal crystallisation of milk fat

Different amounts of phospholipids (0.00‐0.07%) and water (0.00‐0.70%) were added to milk fat. The mixtures were crystallised under isothermal conditions and the crystallisation was monitored by differential scanning calorimetry and pulsed nuclear magnetic resonance. The crystallisation behaviour was described with the Avrami and Gompertz model which was fitted by non‐linear regression. Variance analysis revealed significant effects, whereas especially the induction time was influenced: higher concentrations of water seemed to decrease the induction time, while higher amount of phospholipids delayed the onset of crystallisation. No interaction effects between phospholipids and water were observed. An attempt to explain the effect of phospholipids on the induction time, based on the molecular interactions between phospholipids and triglycerides is proposed. This principle can be applied for sn‐1, 2 diglycerides as well.     

Effects of Low-dose Electron Beam Irradiation on Respiration, Microbiology, Texture, Color, and Sensory Characteristics of Fresh-cut Cantaloupe Stored in Modified-atmosphere Packages

Fresh‐cut cantaloupe was placed in modified‐atmosphere packages (4% oxygen, 10% carbon dioxide) and irradiated at 0 (control), 0.5, and 1.0 kGy. Irradiated samples had a lower and more stable rate of respiration than non‐irradiated samples over about 20 d. Total plate counts were higher (P < 0.05) in non‐irradiated control samples through day 11 (Trial 1) and for all dates tested (Trial 2). Color and texture remained stable for the duration of each study as measured by instruments and trained sensory panels. Sensory evaluation rated the 1.0‐kGy sample highest in “sweetness” and “cantaloupe flavor intensity” and lowest in “off‐flavor” after 17 (±3) d of storage. Low‐dose electron beam irradiation of fresh‐cut cantaloupe with modified‐atmosphere packaging offers promise as a method of extending shelf life.     

Modelling mass transfer phenomena and quantification of ventilation performance in a full scale installation

This paper outlines development of a low order model that can be used for control purposes and quantification of ventilation performance in ventilated systems. First informative pollutant transport data is generated using numerical simulations. Later on, identification procedures are followed to build a low order transfer function model from the CFD generated input–output data. The obtained results demonstrate that first order model can sufficiently describe the dominant mass transfer dynamics in the ventilated air space. Afterwards classical mass balance equation is used to explain the objectively formulated model in a meaningful manner. The developed model is compact in structure and accurate in nature making it an ideal input for model based controller algorithm development. Furthermore its model parameter is found to be an inverse of the local mean age of air. Therefore the model can also be used to assess ventilation performance.     

Immunological characterization, lipid dependence, and subcellular localization of CTP:phosphoethanolamine cytidylyltransferase purified from rat liver. Comparison with CTP:phosphocholine cytidylyltransferase

CTP:phosphoethanolamine cytidylyltransferase (ET) (ethanolamine-phosphate cytidylyltransferase, EC 2.7.7.14), which is generally considered as the rate-regulatory enzyme of phosphatidylethanolamine synthesis via the CDP-ethanolamine pathway, was purified to homogeneity from a rat liver postmicrosomal supernatant. A polyclonal antibody was raised against the enzyme in rabbits and subsequently purified by affinity chromatography. The affinity-purified antibody recognized one single immunoreactive 49.6-kDa protein band on SDS-polyacrylamide gel. The enzyme showed an isoelectric point at a pH of 6.5 and was sensitive to various sulfhydryl reagents. Cross-reactivity experiments of ET and CTP:phosphocholine cytidylyltransferase (CT) (choline-phosphate cytidylyltransferase, EC 2.7.7.15) with their corresponding antibodies showed that these enzymes were immunologically distinct. In contrast with the well known lipid dependence of CT, the activities of both purified and cytosolic ETs were not affected by the presence of various phospholipid preparations. Differential centrifugation studies as well as release experiments with digitonin-permeabilized hepatocytes demonstrated that ET, unlike CT, is not associated with cellular organelles. However, amino acid analysis of ET revealed a high content of hydrophobic amino acids, suggesting a possible association of this enzyme with some kind of cellular structure in the hepatocyte.     

Role of adhesion molecules in the homing and mobilization of murine hematopoietic stem and progenitor cells

Bone marrow (BM) transplantation still must overcome multiple difficulties and should benefit from better understanding of stem-cell homing and mobilization. Here, we analyzed the involvement of several adhesion molecules in the two processes by treating mice with monoclonal antibodies against these molecules. Treatment of lethally irradiated mice grafted with isogeneic BM cells showed that at least two migration pathways are important for stem-cell homing to the BM, whereas only one of them is involved in lodging of colony-forming unit-spleen (CFU-S) in the spleen. We confirm that the VLA-4/VCAM-1 adhesion pathway is important for stem-cell homing to the BM only and show that CD44 is involved in CFU-S lodging in both BM and spleen. These results show that entry of CFU-S into the spleen is regulated. The observation that when one migration pathway is altered, CFU-S do not enter the BM via the other pathway may indicate that the two mechanisms involved in CFU-S homing into the BM are linked. The adhesion molecules VLA-4 and CD44 are also implied in the mobilization of stem cells into the blood stream of mice injected once with anti-VLA-4 or anti-CD44. Anti-VLA-4 administration led to a significant increase in circulating stem cells as early as 8 hours after treatment. Stem cells mobilized by anti-VLA-4 comprise cells with high self-renewal potential and thus may be used for long-term reconstitution of the hematopoietic tissue.     

Power losses in steel pipe delivering very large currents

This paper presents a finite difference time domain solution for the electromagnetic fields in ferromagnetic conducting steel pipes of the type used to deliver large currents for in situ heating of heavy oil reservoirs and for in situ environmental decontamination. A method is described whereby a single measured hysteresis loop can be used to deduce the family of hysteresis loops that governs the variable magnetic behavior throughout the pipe wall. Hysteresis and eddy current losses are calculated, and it is shown that hysteresis effects greatly alter the eddy current distribution and can more than triple the total power losses in the steel pipe when compared to the power losses that would be present if hysteresis effects are ignored and magnetic permeability is assumed constant     

Modeling and molecular dynamics of glutamine transaminase K/cysteine conjugate beta-lyase

The homodimeric, pyridoxal 5'-phosphate (PLP)-dependent enzyme glutamine transaminase K/cysteine conjugate beta-lyase (GTK/beta-lyase) has been implicated in the bioactivation of chemopreventive compounds. This paper describes the first homology model of rat renal GTK/beta-lyase and its active site residues, deduced from molecular dynamics (MD) simulations of the binding mode of 13 structurally diverse cysteine S-conjugates and amino acids after Amber-parametrization of PLP. Comparison with Thermus thermophilus aspartate aminotransferase (tAAT) and Trypanosoma cruzi tyrosine aminotransferase (tTAT), used as templates for modeling GTK/beta-lyase, showed that the PLP-binding site of GTK/beta-lyase is highly conserved. Binding of the ligand alpha-carboxylate-group occurred via the conserved residues Arg(432) and Asn(219), and Asn(50) and Gly(70). Two pockets accommodated the various ligand side chains. A small pocket, located directly above PLP, was of a highly hydrophobic and aromatic character. A larger pocket, formed partly by the substrate access channel, was more hydrophilic and notably involved the salt bridge partners Glu(54) and Arg(99*) (* denotes the other subunit). Ligand-binding residues included Leu(51), Phe(71), Tyr(135), Phe(373) and Phe(312*), and pi-stacking interactions were often observed. Tyr(135) and Asn(50) were prominent in hydrogen bonding with the sulfur-atom of cysteine S-conjugates.The observed binding mode of the ligands corresponded well with their experimentally determined inhibitory potency toward GTK/beta-lyase. The current homology model thus provides a starting point for further validation of the role of active site residues in ligand-binding by means of mutagenesis studies. Ultimately, insight in the binding of ligands to GTK/beta-lyase may result in the rational design of new ligands and selective inhibitors.     

ESCA-Untersuchungen an geätzten polytetrafluoräthylen-folien

In order to glue poly tetrafluoroethylene-films the surface of the polymer has to be etched. The etching is achieved by elemental sodium in liquid ammonia. The nature of the etched surface was investigated by means of ESCA (elektron spectroscopy for chemical analysis). No nitrogen, no sodium and most remarkably no fluorine was found. The surface contains only carbon and oxygen both of only one chemical sort. Contact with bromine or oxygen desactivates the etching. The desactivation is done by molecular oxygen only, not by oxygen compounds like water or methanol.