Preparation of autologous bone marrow grafts for cryopreservation using the AS104 cell separator

The heterocomplex of glycoproteins E and NS1 of tick-borne encephalitis (TBE) virus was isolated from culture fluid of continuous SPEV (porcine embryo kidney) cells by affinity chromatography on CL4B sepharose with immobilized monoclonal antibodies to TBE virus protein NS1. Comparison of the TBE E-NS1 heterocomplex from culture fluid and cells showed the predominance of secreted extracellular form. A similar TBE virus heterocomplex E-NS1 was revealed in the blood sera of patients with TBE but not in their lymphocytes. Extracellular localization of the E-NS1 complex at the late stage of infection rules out its hypothesized participation in the replication of TBE virus. Virtual absence of the heterocomplex and presence of proteins E and NS1 in high concentrations in the cells makes the nonspecific aggregation of these proteins impossible. Evidently, the extracellular heterocomplex E-NS1 may react with virusspecific antibodies or with cytotoxic T lymphocytes.     

What can we learn from the Monte Carlo simulation of the glass transition of polymer melts?

The use of coarse-grained lattice models for the modelling of the glassy freezing in of polymer melts is discussed. The bond-fluctuation model is shown to be a reasonable compromise between simulation efficiency and realistic chemical detail. The potential energy, favoring large values of the length of effective bonds, is at low temperatures in conflict with the tendency for dense packing of the effective monomers and this “geometrical frustration” is responsible for the glass transition of this model. It is shown that many physical properties of the model are in surprisingly close agreement with experiments. Open problems and directions for future research are briefly discussed.     

Hydrogenases, accessory genes and the regulation of [NiFe] hydrogenase biosynthesis in Thiocapsa roseopersicina

The purple (Sulphur) phototrophic bacterium, Thiocapsa roseopersicina BBS contains several [NiFe] hydrogenases, of which two are membrane bound. Mutant T. roseopersicina cells, carrying deletions in both gene clusters showed hydrogenase activity. This activity was located in the cytoplasm. The structural gene cluster hoxEFUYH was identified and sequenced. In addition, genes homologous to hupUV/hoxBC, the hydrogen sensing hydrogenase have been identified and sequenced.Regulation of hydrogenase biosynthesis was studied in detail for HydSL (renamed HynSL). A random mutagenesis system was optimised for T. roseopersicina. One of the mutations was in a gene similar to that coding for the HypF proteins in other organisms. Inactivation of the hypF gene resulted in a 60-fold increase in hydrogen evolution under nitrogen fixing conditions. In addition to hypF, the following accessory genes were identified: hydD, hupK, hypC1, hypC2, hypDE. Characterisation of the corresponding gene products and search for additional accessory genes are in progress.     

Crack formation and fracture energy of normal and high strength concrete

The crack path through composite materials such as concrete depends on the mechanical interaction of inclusions with the cement-based matrix. Fracture energy depends on the deviations of a real crack from an idealized crack plane. FRACTURE energy and strain softening of normal, high strength, and self-compacting concrete have been determined by means of the wedge splitting test. In applying the numerical model called “numerical concrete” crack formation in normal and high strength concrete is simulated. Characteristic differences of the fracture process can be outlined. Finally results obtained are applied to predict shrinkage cracking under different boundary conditions. Crack formation of high strength concrete has to be seriously controlled in order to achieve the necessary durability of concrete structures.     

Nachweis von Maillard-Produkten in Malzen, Bieren und Braucouleuren

Zusammenfassung Bei der Maillard-Reaktion reagieren primär reduzierende Zucker mit den freien Aminogruppen der Aminosäuren. Dabei entstehen aus Aldosen als erste stabile Zwischenprodukte die 1-Aminosäure-1-desoxy-ketosen (Amadori-Verbindungen). In Malzen konnten zehn Amadori-Verbindungen quantitativ bestimmt werden. Sie entstehen während des Darrens des Malzes. Aufgrund unterschiedlicher Darrbedingungen unterscheiden sich die Malztypen im Gehalt und im Muster dieser Substanzen. Während der Erhitzungsvorgänge beim Brauprozeß (Maischen, Würzekochung) werden die Amadori-Verbindungen etwa zur Hälfte abgebaut, dagegen sind bei der an schließenden Gärung keine Veränderungen zu beobachten. Aus dem Gehalt und dem Muster der Amadori-Verbindungen im Bier können somit Rückschlüsse auf das verwendete Malz gezogen werden. Bei der Herstellung von Braucouleuren werden Ammoniak bzw. Ammoniumverbindungen als Aminokomponenten eingesetzt. Die Couleure enthalten deshalb keine 1-Aminosäure-l-desoxy-ketosen, dafür aber Desoxyfructosazine, die bei der Reaktion von Zuckern mit Ammoniak entstehen. Diese Pyrazinderivate wurden in Braucouleuren in hohen Mengen (2–6 g/100 g) gefunden. Es wird eine Methode vorgestellt, mit der ein Zusatz von Braucouleuren zum Bier über die Bestimmung der Desoxyfructosazine eindeutig nachgewiesen werden kann.

---

Detection of Maillard products in malts, beers, and brewing couleurs

During the Maillard reaction, the reducing sugars first react with the free amino groups of the amino acids. With aldoses, 1-amino-l-deoxyketoses (ketose-amino acids, Amadori compounds) are the first stable intermediates to be formed. In malts ten different Amadori compounds could be determined that formed during the kiln-drying of malt. Dependent on the kiln-drying conditions, the different types of malt contain different amounts and proportions of these compounds. During the brewing process (mashing, mash wort cooking) about half of the Amadori compounds are decomposed, whereas during fermentation no changes can be observed. Therefore the amount and composition of Amadori compounds detected in beer may indicate the type of malt used. During the production of brewing couleurs, ammonia or ammonium compounds react with sugars and deoxyfructosazines are formed. In brewing coleurs, relatively high amount of these pyrazine derivatives (2–6 g/100 g) could be found. An analytical method is described for the quantitative determination of deoxyfructosazines, indicating an addition of brewing couleur to beer.

     

On-line process control of a fluidized bed reactor with non-catalytic gas/solid reaction

In a bench-scale, stainless steel reactor, experiments were carried out to investigate fluidized bed behavior by means of on-line process control. The non-catalytic thermal decomposition of sodium hydrogen carbonate to sodium carbonate, carbon dioxide and water was used a model reaction. The experimental equipment was provided with control systems and reulating units which were connected to a PDP 11/40 computer by means of suitable analogue and digital input/output interfaces. The operating conditions are highly influenced by the chemical reaction as well as by the fluid-dynamical behavior of the reactor. Several experiments were carried out to evaluate the kinetics of the model reaction. The fluid-dynamics was investigated by means of on-line experiments with and without chemical reaction. Based on the experimental results, a model was developed to describe the whole process so that model simulations should yield information on the process itself. With this model, strategies are tested before they are applied to the process computer for on-line process control.     

Assessment of Grinding Fluid Effectiveness in Continuous-Dress Creep Feed Grinding

Creep feed grinding is a high-productivity abrasive removal process that is often limited by thermal damage and high wheel wear. A review of current industrial practices in the area of fluid supply optimisation in grinding shows that very little knowledge of the pressure, flowrate and method of application exists in industry. This paper presents an experimental procedure to evaluate fluid supply conditions in grinding on a continuous-dress creep feed grinder. Using tapered workpieces, the authors have evaluated the influence of wheel speed and material removal rate on grinding fluid effectiveness, based on the material removal rate at the position of the wheel along the ramp when burn starts to occur and the corresponding spindle power surge. Correlations are investigated between visible discoloration, metallurgical examinations and change in spindle power, in order to establish the onset of grinding burn. This procedure serves to determine the upper limit of material removal rate or - respectively - the lower limit of fluid flow rate for given grinding systems consisting of specified wheel type, material type, fluid type and fluid supply nozzle. The advantage of the presented method is its easy and time saving application in industry, but it is also of help to researchers who need to optimise fluid supply conditions prior to their grinding tests.     

基于中子成像的水泥基材料毛细吸水动力学研究

总结了国内外有关水泥基材料毛细吸水的动力学机理及其现有模型,应用中子成像技术对其毛细吸水过程进行了可视化再现,对水分侵入的空间分布规律进行了定量分析。结果表明,在毛细孔吸附力作用下,水分前锋不断向水泥基材料内部推进,在吸水初期速度较快,后趋于平缓直至稳定;水分侵入曲线在深度和含量上同时增 长,可以由线性+反S形模型来描述其空间分布特点,并与实测结果吻合良好;现有的 “时间开方” 及其修正模型对毛细吸水的后期预测不太合理,本文提出的渗透系数双曲线衰减模型更符合真实结果。     

Experimental and theoretical investigation of a multipass, plane mirror, femtosecond dye laser amplifier

Femtosecond pulses of a passive mode-locked Rhodamine-6G dye laser are amplified in a double-stage, three-pass, plane mirror, Sulforhodamine-101 amplifier system. Saturable filters (Schott glass RG645 and Malachite Green) are used to suppress amplified spontaneous emission. Input pulses of 110-fs duration are broadened to 240 fs in the amplifier system and recompressed to 75 fs in a prism-pair compressor. Using a 20-Hz Q-switched Nd:YAG pump laser of 50-mJ second-harmonic output energy, we obtained amplified and recompressed pulses of 180-μJ energy at 625 nm starting with 40-pJ input pulses. The small-signal amplification dynamics is studied numerically. Relevant gain dye and saturable filter parameters are derived. The influence of amplified spontaneous emission is analyzed.