Automated fluorimetry in quality control of pasteurized and ultra-high temperature-treated starch soup

Automated monitoring of the microbiological quality of heat-processed foods by the resazurin reduction test was applied to microtitration plate incubator-fluorimeter technology. The appearance and disappearance of the fluorescing peak of resorufin was monitored on microtitration trays. Pasteurized or ultra-high temperature-treated starch-based soup was used as the model food system. Bacillus subtilis spores (ultra-high temperature treatment) and vegetative cells of Enterococcus faecalis (pasteurization) were inoculated into the soup before the heat treatment at levels which resulted in some survival. The timing of appearance of maximum fluorescence correlated with the number of bacteria in pre-incubated samples. Automated resazurin-reduction fluorimetry was compared with conventional plating, turbidometry and microcolony count by the direct epifluorescent filter technique. The results of the resazurin test correlated well with those of all the other methods tested. Fluorimetry had the advantage that the results could be read within 1–5h and the reproducibility was superior to the other methods.     

Microstructure-composition relationships and Ms temperatures in Fe-Cr-Mn-N alloys

Microstructure-composition relationships and M_s temperatures have been determined in high purity nitrided Fe-Cr-Mn alloys, as part of a program to develop improved corrosion-abrasion resistant steels with unstable austenitic microstructures. Compositions in the range 8 to 12 pct Cr, 0 to 10 pct Mn, and 0 to 0.6 pct N were investigated by a resistivity technique to determine M_s temperatures and by X-ray diffraction and metallography to determine constitution. Hardness measurements were also made. At the low alloy end of the range, microstructures after annealing and air cooling are fully martensitic while at the high alloy end they are fully austenitic. At intermediate compositions, mixed martensite-austenite microstructures (with epsilon present as a minor phase in some cases) and unstable austenitic microstructures are obtained. The austenitic alloys contain a high density of stacking faults and the unstable austenitic alloys transform to martensite on deformation. At low N contents (up to at least 0.25 pct N) the M_s-composition relationship is linear and described by: M_s = 555 - 9(Cr - 8) - 40Mn - 450N [1] where M_s is in °C and Cr, Mn, and N are the weight percentages of these elements. At higher N contents, the M_s generally falls more rapidly with increasing nitrogen content. Nitrogen solubility at 1050 °C exceeds about 0.3 pct in all alloys and increases with increasing Cr and Mn content. In commercial purity steels, unstable austenitic microstructures are expected to be obtained in compositions around 10 to 14 pct Cr, 8 to 12 pct Mn, and 0.1 to 0.3 pct N when the total level of these elements is selected to ensure the M_s is below room temperature.     

The femur-tibia control system of stick insects--a model system for the study of the neural basis of joint control

In a form of top-down analysis, the femur-tibia control system of stick insects is investigated. Open-loop experiments show that it is mainly velocity-sensitive with an extremely low velocity-threshold, that it possesses a very high gain and that it has only a very small phase reserve and thus works close to instability. The closed-loop system generates catalepsy. The system consists of a single sense organ with approximately 80 sense cells with known characteristics, a small number of interneurones (mainly non-spiking ones) and a small number of motor neurones. The characteristics of the whole system can quantitatively be attributed to the characteristics of its elements. The gain of the loop is state-dependent and the system is 'switched off' during active movements and replaced by a control system with different attributes. It is discussed that most of the characteristics of this system are, at least qualitatively, similar to joint control systems in other animals. Because the described system can be more easily investigated than other systems (especially in vertebrates) it can serve as a model against which more complicated joint control loops may be compared.     

Nontuberculous mycobacteriosis as a complication of the Swyer-James syndrome

The chest radiograph of a 35-year-old man with fatigue, exertional dyspnoea and haemoptyses revealed a cavity in the left upper lobe and a shrunken left lung with radiolucency greater than that on the right. Acid-fast rods in sputum were identified as Mycobacterium kansasii on culture. Scintigraphy showed a 9% residual perfusion on the left and abnormal ventilation, compatible with Swyer-James syndrome. This had favoured the development of a mycobacterial infection. There was also a decrease in ciliary function (rate of 4-7 Hz, normal: 10-11). Treatment, begun when tuberculosis had been suspected, was after sensitivity tests changed to a combination of rifampicin (600 mg), ethambutol (1600 mg) and protionamide (500 mg) daily. There was marked regression of the findings within 4 weeks, but treatment was prematurely stopped after 11 months. Two years later there was a recurrence which again responded well to the same drug regimen with additional sulphamethoxazole (1600 mg/d).     

Verbesserung des Vakuums in Isoliergefäßen aus Glas

Improving the vacuum would increase the insulation capacity of commercially available glass containers by a factor of about two. To do this, pressures of 10^?4 mbar must be attained. Different approaches were taken to meet this objective. As an alternative to today's commonly practiced sealing method, three possibilities are introduced which eliminate the necessity of pump stub narrowing which causes reduced conductance. Furthermore, depending on the sealing process used, the gases occuring during sealing are either avoided completly or they can at least be reduced by having the chance of exact temperature control resp. by a lower separation temperature. A completly different approach was taken by using Getters, of which a metal hydride on a TiVMn base proved especially suitable. It is activated by heat and can be integrated into the normal production process without any problem. Aside from a shorter pump period, the added advantage here is the containment of the gasses occuring during sealing as well as that of the longterm gasses.     

Human erythrocytes bearing electroinserted CD4 neutralize infection in vitro by primary isolates of human immunodeficiency virus type 1

Human erythrocytes bearing electroinserted full-length CD4 (RBC-CD4) can bind and fuse with a laboratory strain of human immunodeficiency virus type 1 (HIV-1) or with T cells infected by HIV-1. Here we show that RBC-CD4 neutralize primary HIV-1 strains in an assay of cocultivation of peripheral blood mononuclear cells (PBMC) from HIV-1-infected persons with uninfected PBMC. RBC-CD4 inhibited viral p24 core antigen accumulation in these cocultures up to 10,000-fold compared with RBC alone. Viral p24 accumulation was inhibited equally well when measured in culture supernatants or in call extracts. The inhibition was dose-dependent and long-lived. Two types of recombinant CD4 tested in parallel were largely ineffective. The neutralization of primary HIV-1 by RBC-CD4 in vitro was demonstrated in PBMC cultures from 21 of a total of 23 patients tested at two independent sites. RBC-CD4 may offer a route to blocking HIV-1 infection in vivo.     

Characterisation of sub-100 nm-MOS-transistors processed by optical lithography and a sidewall-etchback technique

This paper describes the fabrication of NMOS-transistors with a geometric gate length of down to 50 nm using conventional optical lithography and a modified sidewall-etchback process. Based on measurements the transistors are characterised and their device parameters are compared to simulations. Finally the procedures for further optimisation of the process will be explained.     

Nature of terpenoids of aTaxodioxylon gypsaceum from the fossil forest of Dunarobba (Italy)

A specimen fromt he fossil forest of Dunarobba (Central Italy) attributed toTaxodioxylon gypsaceum was chemically analyzed particularly for its terpene content. Main chemical constituents show variations related to ageing and carbonization process, while terpene content exhibits a drop of mono- and sesquiterpenes in favour of diterpenes and higher MW compounds. All components are exclusively hydrocarbons and represent alicyclic or partially aromatic structures. The identified families include abietane, phyllocladane, norabietane and norpimarane among diterpenes and traces of cadinane and selinane among sesquiterpenes.