Effect of temperature on growth characteristics of Bacillus cereus TZ415

The effect of temperature on the maximal specific growth rate was studied in Bacillus cereus between 5 and 40 degrees C cultivated in courgette broth and rich medium (J broth). B. cereus grown from 5 to 38 degrees C in rich medium. No growth was observed in courgette broth below 10 degrees C. The Arrhenius plot was fitted from experimental data of B. cereus grown in rich medium and at regulated pH, oxygen and temperature. Two domains which are separated by a critical temperature around 13 degrees C can be distinguished with regard to temperature dependence of maximal specific growth rate. Over the cold domain from 5 to 13 degrees C, the temperature characteristic was 2.6 fold higher than over the sub-optimal domain from 13 to 38 degrees C suggesting that the growth temperature regulates several metabolic pathways.     

Infrared nanoscopy of dirac plasmons at the graphene-SiO₂ interface

We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding 2 orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO(2) substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage.     

The extraction of yellow gentian root (Gentiana lutea L .)

 Several solvents have been investigated for the preparation of bitter compounds of gentian roots (Gentiana lutea L.) for food applications. The highest concentrations of the bitter compounds, amarogentin and gentiopicroside, were obtained with ethanol : water 55 : 45 (v/v), propylene glycol: water 30 : 70 (v/v) and ethanol: propylene glycol: water 20 : 20 : 60 (v/v/v). Enzyme treatment prior to solvent extraction gave a greater extract yield (3.5%) but the amarogentin and gentiopicroside concentrations remained the same. The volatile fraction was affected by the solvent used through the formation of esters of organic acids from the plant. Received: 22 January 1997 / Revised version: 18 March 1997     

Laparoscopic gastrostomy

Feeding gastrostomy is a method for treating patients unable to ingest food orally. After our experience and good results with the Janeway technique, we decided to perform it by the laparoscopic method. Our first excellent results in seven patients suggest that laparoscopic Janeway gastrostomy is an easy, rapid and efficient surgical technique.     

Portal hypertensive colopathy: histologic appearance of the colonic mucosa

BACKGROUND/AIMS: The aim of this study was to evaluate macroscopic and histologic disorders of the colon in rats with portal hypertension. METHODOLOGY: The animals were divided into two groups: 10 rats in the experimental group and 10 controls. Portal hypertension was induced by a partial ligation of the portal vein. We assessed the histologic appearance and macroscopic alterations of the colonic mucosa 12 weeks after the induction of portal hypertension. RESULTS: The macroscopic results showed the presence of the typical signs of portal hypertension, with dilatation and tortuosity of the mesenteric veins and hyperemia of the rectum and colon. Histologic study revealed a marked dilatation in the microcirculation at the level of the ascending colon (20 +/- 2 micra in diameter) and rectum (30 +/- 4), with a tendency to group the lesions. Submucosal edema without inflammatory signs was observed. CONCLUSION: The existence of these lesions in the colon and rectum can be the cause of hemorrhage, as in the gastropathy of portal hypertension and should be considered in cases of undiagnosed hemorrhage in patients with portal hypertension.     

A novel optical waveguide microcantilever sensor for the detection of nanomechanical forces

This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels with microcantilevers acting as optical waveguides operated in the visible range. The principle of operation is based on the sensitivity of energy transfer between two butt-coupled waveguides to their misalignment with respect to each other. The technique can be considered an alternative to the known methods used for the readout of the nanomechanical response of microcantilevers to the external force exerted on them. The cantilever displacement can be detected with a resolution of 18 fm//spl radic/Hz. The limit is generally defined by the shot noise of a conventional photodetector used for the readout of the output signal. Real-time parallel monitoring of several channels can be realized. In contrast to devices based on the atomic force microscope detection principle, no preliminary alignment or adjustment, except for light coupling, is required. The detection of the cantilever deflection at subnanometer range was demonstrated experimentally.     

An assessment of graphitized carbon fiber use for electrical power transmission

Significant progress has been made in the last few years toward the production of a highly conductive carbon filament. Graphitized carbon fibers, made from a variety of precursor materials such as rayon, polyacrylonitrile (PAN), pitch, mesophase pitch and benzene, have electrical conductivities in the range $\text{10}{}^6\text{? 10}{}^7\text{(Ω}\text{m}\text{)}{}^{\mathrm{?1}}$, tensile strengths in the range 1–3 GPa, tensile moduli in the range 100–700 GPa and densities in the range 1.8 ?2 2.2 × 10³ kg/m³. These properties suggest that graphitized fibers may have potential as current carriers for electrical power transmission. This paper examines the physical reasons for the electrical and mechanical properties and evaluates prospects for fibers with better electrical conductivity without degradation of mechanical properties. Chemical doping (intercalation) of the highly graphitized carbon fibers is found to be capable of achieving increases in conductivity of 5 to 15 times with some degradation in tensile strength. Various applications for electrical power transmission usage are examined, i.e., underground and overhead conductors, underground pipe, overhead towers and submarine cable. Near-term usage is most probable in towers and submarine cable, where high strength-to-weight advantages may offset the present failure of fiber electrical conductivity to equal aluminum or copper values.     

Aqueous Extraction and Membrane Isolation of Protein from Defatted Gevuina avellana

ABSTRACT: Proteins from defatted Gevuina avellana seeds were extracted in aqueous media. Protein extraction was limited at liquid-to-solid ratios under 12 g/g, but was not significantly affected by temperatures in the 25 to 45 °C range. The maximum protein extractability occurred both at acidic and alkaline pH; the presence and concentration of NaCl affected it differently, depending on the extraction pH. Up to 3 extraction stages with whey recycle after ultrafiltration were performed, without affecting the protein extraction yield. The functional properties of the protein isolated with membranes were similar or better than those from isoelectric precipitation.