Interaction of food packaging material and selected food components under high pressure

Abstract

Interactions between ethanolic solutions of p-cymene and acetophenone and different polymer packaging materials. were studied at 500 MPa and 25° C. p-Cymene solution, filled into low-density polyethylene bags, lost 30% of its aroma concentration after 24 h at 500 MPa compared to a 60% loss at atmospheric pressure. The decrease was strongest within the first 15 min. Using LDPE/HDPE/LDPE bags, losses were 20% and 30%, resp. Applying the “bag in the bag” method, p-cymene concentrations measured inside and outside the inner bag has shown sorption by the pressurized film to be one third of that by the non-pressurized. In PET/AI/LDPE bags impermeable to p-cymene, sorption was confined to the inner LDPE layer and caused higher loss in the non-pressurized sample. Acetophenone has not been found to interact with the polymer during pressure treatment, while at atmospheric pressure sorption loss in aroma concentration was nearly 70% after 60 h.     

Zur Empfindlichkeit von Festkörperspurdetektoren

Es werden verschiedene Festkörperspurdetektor-Materialien hinsichtlich ihrer Empfindlichkeit gegenüber Bestrahlung mit α-Teilchen und zum Teil auch gegenüber Protonen und Deuteronen verglichen. Die speziell für den Einsutz als Festkörperspurdetektor hergestellten Zellulosenitrat-Folien wurden als empfindlichste Detektoren ermittelt.     

Fast Neutron Sensitivity of TL Detectors using Proton Radiator Techniques

TL materials have a small intrinsic sensitivity for fast neutrons. In order to increase this sensitivity one uses hydrogen containing radiators giving recoil protons as a result of the neutron interaction. By combining the proton radiator technique with the use of TL detectors having various glow peaks with a different response to recoil protons an additional sensitivity yield can be reached. The paper deals with the calculation procedure for the (radiator) sensitivity component. For the LiF phosphors TLD-600 and TLD-700 calculated and experimentally determined fast neutron sensitivities are presented for the glow peaks V and VII. The results show that for accident dosimetry a sufficient agreement of the dedector response with the dose-to-fluence conversion factors is obtained.     

High pressure infiltration sintering behavior of WC-Co alloys

In this paper, two average tungsten carbide particle sizes of 2, 0.5?μm are placed respectively, in contact with a WC-16Co substrate, pressed at the pressure of 4.5–5.5?GPa, and heated to temperatures ranging from 1350°C to 1500°C in a large-volume cubic press. During the process Co was forced out of the WC-16Co substrate into the compressed powder. The resulting infiltrated samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), Vickers hardness and cutting performance tests. The results of XRD confirmed that the sintered bulks have WC and Co phases. The scanning electron microscopy (SEM) analysis reveals that the WC grains in well-sintered alloys are round in shape and cobalt with lower content is uniformly dispersed in the WC grain boundaries. The sintered sub-micron WC-Co alloy with a cobalt content of 3.8?wt% exhibits a prominent combination of high hardness value of 23.1?GPa and a large fracture toughness value of 8.6?MPa?m^½. The high-speed cutting tests indicating its cutting performance is significantly superior to the commercial YG6X (WC-6?wt%Co with WC grain size of 0.5?μm).     

高功率激光稳定腔选模分析

讨论了在有限菲涅耳数时，稳定凹－凸腔的高功率激光选模特性，研究表明当稳定凹－凸腔工作在临近界稳区时，基模体积显著提高，具有良好的选模效果。     

Development of copolymer of CR-39 with high sensitivity to low let particles

Several types of copolymers of CR-39 were prepared to find its usefulness as a nuclear track detector of high sensitivity. Track responses of these copolymers were investigated by irradiating energetic ions from proton through Ar. The copolymer of CR-39 monomer with N-isopropylacrylamide (NIPAAm) shows higher sensitivity than that of pure CR-39 for low LET particles such as protons. Preliminary results are reported for the track responses of copolymers (CR-39/NIPAAm) with various contents of NIPAAm as well as the etching properties.     

试论高比能量电池进展

在综述电化学近５０年来比能量提高情况的基础上，讨论了现代科技发展对电池比能量的要求，以及当今电池能在多大程度上满足这些要求，并讨论了进一步提高电池比能量的可能性及可能途径．     

杨氏模量用电学量转换测量的设计

本文在传统的力学量测定的实验基础上,利用电学量参数变化测定杨氏模量,达到研究应力与应变的规律。     

A study of time over threshold (TOT) technique for plastic scintillator counter

A new charge measurement method, time over threshold (TOT), has been used in some gas detectors lately. Here TOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics.     

Fundamentals of optical design in rotating mirror cameras

The elementary optics of rotating-mirror high-speed cameras are analysed geometrically. The images in an off-axis scanning mirror are shown to lie on Pascal's limacon. The Miller principle by which shuttering is accomplished is described. A simple estimate of motion blurring is compared with the Rayleigh criterion.