Use of Temperature- and Humidity-Dataloggers in Food Engineering

The use of dataloggers in food engineering is discussed in two examples. The first example describes the measurement of temperature and humidity in a bulk tank car during transport and unloading. In the case of wheat flour the relative humidity in the air raises from about 80% r.h. to values near 100% r.h. at the air compressors for pneumatical unloading start working. The second example shows the use of the datalogger in education on heat transfer. The device was fixed in an ice cream sample which was placed in a store at –25°C. The measured hardeningtime agrees well to theoretical heat transfer calculation.This revised version was published online in November 2005 with corrections to the Cover Date.     

从自旋冰到自旋液态的渡越——结构与磁性质的演化

使用固相反应法得到了Ho_2-xTb_xTi₂O₇（x=0,05,1,15,2）系列多晶样品.X射线衍射（XRD）实验与2K到300K温度区间的直流磁化率测量结果显示,随着Tb即是x的增加,体系由自旋冰Ho₂Ti₂O₇向自旋液Tb₂Ti₂O_{7关键词： 自旋冰 自旋液体 自旋阻挫 晶格结构}     

磁单极子进展概述

自磁单极子概念被狄拉克提出以来,不管是理论还是实验物理学家都一直在努力寻找,但迄今仍然没能找到它们存在的确凿证据.最近,一些凝聚态物理学家声称在动量空间以及自旋冰材料中找到了磁单极子存在的有力证据,并通过磁单极子的集体激发行为解释了一些新颖的物理现象.这使得磁单极子艰难的探索之路出现了一丝新的曙光.作为电动力学教学内容的补充,本文拟把磁单极子的最新进展做一个概述,让大学生对此有一个全面的认识,从而激发他们学习和科研的兴趣.     

硫酸海胆内容物多糖化学结构的质谱法研究

将海胆内容物硫酸多糖XB-3进行脱硫得到多糖XB-3D,分别对XB-3和XB-3D进行甲基化,对脱硫前后的部分甲基化糖进行气相色谱-质谱测定,通过质谱分析法得出XB-3和XB-3D的结构信息,包括其主链和支链的构成、连接方式、硫酸基取代位置和结构模型。     

黄河河道冰水情定点连续自动检测及数据分析

根据黄河中上游流域冰水情监测以及预防凌汛灾害的需求,设计了一种适合黄河河道的冰水情自动测报系统.该系统由基于空气、冰与水电阻特性差异的冰层厚度传感器、DS18B20的温度梯度传感器以及智能处理仪构成.采用该系统在内蒙托克托县黄河河道进行了黄河封冻期河道冰层厚度连续监测试验,获取了大量的现场实测数据,对采样数据进行分析,提出了判别冰层厚度的平均滤波算法,实现了对冰层生消变化全过程的自动监测.     

Estimates of Europa’s ice shell thickness and strain rate from flanking cracks and bulge along Ridge R

Europa, the second Galilean satellite outward from Jupiter, has an outer layer of water of about 100 km thick and an outmost ice shell. The thickness of the ice shell is very important in understanding Europa’s habitability and thermal history, but estimates from different studies are very inconsistent, ranging from 0.2 to 30 km. Here we obtain an estimate of the ice shell thickness from locations of flanking crack and forebulge along Ridge R. Considering the water’s heating process to nearby ice shell in the crack, a flexure model is applied and it suggests the thickness of an ice shell to be 500–1500 m without a convective layer. Compared with previous studies using the same method but ignoring the water’s heating process, the rationality and accuracy have been improved dramatically in our results. We also get some constraints on the strain rate and the characteristic temperature T _c, which defines the base of the elastic layer.     

Isotope Studies of Hydrogen and Oxygen in Ground Ice - Experiences with the Equilibration Technique

Abstract

Equilibration technique suitable for a large amount ofsamples is described for hydrogen and oxygen isotope analyses of ground ice, especially ice wedges, including the sampling strategy and the analytical procedure as well as the calibration of the Finnigan MAT Delta-S mass spectrometer in June, 1999. Since for future analyses of ice wedges, a higher sampling resolution with limited sample volume is required, the limit of the equliibration technique for small water samples size of between 0.05 and 5 ml was checked. For water samples smaller than 1ml, corresponding to a molar ratio [H₂O]/[H₂] of smaller than 0.994, a balance correction has to be applied. The experimental errors due to partial evaporation during evacuation, the balance calcultion of the isotope equilibration process, the linearity as well as memory effects of the mass spectrometer for smaples with large differences in δ¹⁸O and δD are tackled in this paper. In the polar regions of Northern Siberia without Late Pleistocene and Holocene glaciation, ground ice is used as an archive for paleoclimate studies. First results of stable isotope measurements on ice wedges clearly show a shift towards heavier isotopes and thus warmer winter temperatures as well as a change in the source of the precipitation between Late Pleistocene and Holocene. These results indicate the high potential of ground ice for paleoclimate studies.     

Effects of fish farm loading on sea grass Posidonia oceanica at Vrgada Island (Central Adriatic): a nitrogen stable isotope study

Analyses of nitrogen stable isotopes in the marine sea grass Posidonia oceanica were used to investigate the influence of fish farming on the coastal ecosystem of Vrgada Island in the Murter Sea, Central Adriatic. The results show a statistically significant ¹⁵N enrichment (up to 4.7‰ at p?<?0.005) in P. oceanica leaf and shoot tissues from fish cage sites with respect to the unaffected offshore reference site of Lumbarda Reef Flat (Kornati Islands). Heavy nitrogen enrichment was also detected in other benthic organisms analysed during this study and is attributed to the absorption and assimilation of ¹⁵N-enriched fish farm derived nitrogen waste.