发酵玉米面条品质评价指标研究

快速准确的评价方法对面条品质改良至关重要。目前对发酵玉米面条品质评价指标及方法还没有统一的标准,本研究用不同的方法（感官评价、质构测试、蒸煮品质测试）对发酵的玉米面条的品质进行了评价,并用SPSS13．0时各参数进行了相关性分析。结果表明,仪器质构测试指标和蒸煮品质测试指标均与感官评分呈极显著相关。其中硬度、咀嚼性能可表征发酵玉米面条的品质,而蒸煮品质测试则可用于表征发酵玉米面条品质的辅助手段。     

Free radical involvement in the oxidation of Victorian brown coal

Electron spin resonance spectroscopy has been used to investigate free radical involvement in the oxidation of Victorian brown coal. Fresh, wet Yallourn brown coal exhibits two superimposed e.s.r. signals due to organic free radicals. The free radicals responsible for the narrow signal interact reversibly with atmospheric oxygen while the broad signal changes intensity dramatically during prolonged exposure to air. Coal:oxygen complex formation may explain these observations. Results also suggest that the free radical content of brown coal increases as a consequence of vacuum drying.     

Determination of carbon C,CH, CH2 and CH3 group abundances in liquids derived from petroleum and coal using selected multiplet 13C n.m.r. spectroscopy

Selected, multiplet C n.m.r. spectra are obtained for three test samples deriving from petroleum and coal sources, by combining gated spin echo (GASPE) and conventional spin echo ¹³C n.m.r. procedures. Each selected multiplet spectrum contains resonances due to only one of the following groups: aromatic C or CH or aliphatic C, CH, CH₂orCH₃. In general artifacts contribute only minor intensity to individual spectra, with the separation between aliphatic CH and CH₃ spectra being the most difficult to achieve. Each spectrum can be integrated to yield the relative abundances of CH_n groups (n = 0 to 3). Selected multiplet ¹³C n.m.r. spectra provide a more detailed view of the component hydrocarbon groups in fossil-fuel derived materials than can be deduced from conventional ¹³C n.m.r. spectra.     

卷烟鉴别仪器分析技术研究进展

介绍了人工嗅觉系统、近红外光谱分析技术和气相色谱或气相色谱-质谱联用3种仪器分析技术在卷烟鉴别中的应用,探讨了仪器分析技术在卷烟鉴别中存在的问题,对应用前景进行了展望。     

N.m.r. line shape-relaxation correlation analysis of bitumen and oil sands

The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent.     

Some aspects of the analysis of coal by X-ray fluorescence spectroscopy

Bituminous coal samples from 84 distinct sources were analysed by conventional British Standards (BS) methods for phosphorus, sulphur, chlorine, ash and the ash-forming elements (calcium, silicon, aluminium, iron, sodium, magnesium, potassium, titanium and manganese). In most cases four determinations were made per element per source. Samples were crushed to ?212 μm (72 BS mesh) and pressed into aluminium cups at 20 t in^?2 (309 MPa) without binder or backing. Two pellets from each sample were analysed by wave-length dispersive X-ray fluorescence techniques, using a spectrometer equipped with a rhodium rube; the X-ray count took 60 s. The X-ray results were calibrated against the conventional results using multiple regression. The accuracy obtained was comparable with routine ‘wet chemical’ techniques. The X-ray technique is suitable for the routine determination of large numbers of samples.     

Direct determination of organic sulphur in raw and chemically desulphurized coals

An electron beam technique has been developed for the direct determination of organic sulphur in coal, using a scanning electron microscope coupled with an energy-dispersive X-ray analysis system with quantitative data reduction capabilities. The direct measurement of organic sulphur is performed on a number of particles of the maceral vitrinite, previously located within the mounted coal sample by reflected light microscopy. The particles are first examined by SEM at ≈5000 × magnification to allow proper identification of most mineral inclusions and to avoid these areas during analysis. The X-rays generated from an area 3 μm in diameter are monitored quantitatively by EDX for sulphur and iron, as well as for calcium, aluminium and silicon. After ensuring that no other elements, indicating mineral matter, are present at the point of analysis, the sulphur value obtained is taken as a measure of the organic sulphur in coal. The results obtained by this technique also allow estimation of the intra- and inter-particle variation in the organic sulphur level. Statistical methods can be used to construct confidence bands about the mean sulphur levels and estimate standard deviations within and between particles. This permits evaluation of the precision of the analysis on a sample-by-sample basis and provides a measure of the heterogeneity of the coal. The SEM-EDX method has been applied to a large number of raw coals and coals chemically desulphurized by the Ames, PETC and Ledgemont oxydesulphurization processes, as well as the molten caustic (Gravimelt) process of TRW Systems Inc. The results of this direct technique agree fairly well with those of the ASTM procedure, for both raw and chemically processed coals, although for the latter the SEM values often show less desulphurization than the ASTM values.     

聚酯装置水质中色度的测定-仪器法和稀释倍数法

色度是衡量聚酯装置废水是否达标排放的重要指标之一,污染较严重的地面水和工业废水色度使用稀释倍数法测定,为提高检验效率、实现检验自动化,也可采用仪器法测定.本实验为仪器法和稀释倍数法的比较.     

X-ray structural parameter for coal

It has been shown that the interatomic distance of ≈0.43 nm in coal is predominantly due to turbostratic-graphitic order. The height of the corresponding peak in the G(r) function which is the Fourier transform of the properly corrected and normalized X-ray diffractogram, has been investigated as a function of the concentration of volatile matter and the heat treatment of the coal. The results clearly show that this new parameter which is based on the whole diffraction pattern, is a useful aid in the study of coal, in particular when the structural changes within one coal are investigated.     

中子活化分析与X-ray荧光谱分析比对鉴定Cr-12钢

采用仪器中子活化分析与X ray荧光谱分析手段 ,对Cr 1 2钢进行比对鉴定 ,两种方法结果吻合 ,文中着重对X荧光分析的典型样品Fe、Cr合金的分析作了探讨