Potentiostatic pulse technique to determine the efficiency of hydrogen absorption by alloys

A potentiostatic pulse technique was used to determine the efficiency of hydrogen entry and trapping in two precipitation-hardened (Inconel 718 and Incoloy 925) and two work-hardened (Inconel 625 and Hastelloy C-276) nickel-base alloys in an acetate buffer (1 M acetic acid/1 M sodium acetate) containing 15 p.p.m. As₂O₃. The data were examined as a function of charging time and overpotential. The trapping efficiency increases with charging time (f _c) and is linearly dependent on (t _c)^1/2 for sufficiently short times. The range of linearity is determined by the apparent trapping constant for the alloy. The entry efficiency is independent of charging time but it can vary with overpotential depending on the value of the charge transfer coefficient () for the hydrogen evolution reaction. In the case of Inconel 718 and Hastelloy C-276, the value of was 1.4, which is consistent with a mechanism for hydrogen evolution involving fast discharge followed by slow electrochemical desorption.     

Use of high-performance liquid-chromatography to determine the metal content of waste water

Conclusions -- A procedure has been developed with a simultaneous determination of Co, Ni, and Cu in waste water, using the Milikhrom microcolumn chromatograph.-- The procedure is simple and rapid (analysis time, 20 min); it eliminates the stage of extraction of the chelates, and is comparable in sensitivity with the atomic-absorption spectrophotometry method.Klinskii Khimvolokno PO. Translated from Khimicheskie Volokna, No. 5, pp. 54–55, September–October, 1992.     

Supercritical fluid extraction to determine the oil content in copra and extracted meal

Supercritical fluid extraction (SFE) was used as a primary method to determine the oil content of copra and its meal. Determination of the oil content of copra takes 9 h, and for meal 6 h are necessary with Soxhlet extraction, whereas SFE determined oil contents in about 10 min. The extremely high oil content of copra makes grinding difficult, as the sample becomes very gummy and it is difficult to remove the entire sample from the grinder. Adding diatomaceous earth to the sample before grinding eliminated the difficulties of cleaning the grinder and also enabled very fast SFE extractions. The variances for Soxhlet and SFE were not significantly different from each other (P>0.10) in both copra and meal oil contents. The 95% confidence interval around the mean differences (SFE-Soxhlet) was (−0.35, 0.90) and (0.08, 0.26) and for copra and meal, respectively. Although the SFE meal oil content (9.81%) was significantly higher than the Soxhlet meal oil content (9.64%), the size of the average difference (0.17%) was relatively small. This small difference was considered acceptable owing to the ability to use SFE in real-time process control. Therefore, SFE can be used to determine the oil content in copra and its meal in less than 10 min.     

利用测井参数交会法确定油水层下限

以铸体薄片分析其岩性并以试油资料为依据,对自然电位、声波、电阻率测井资料进行标准化校正,选取储集层的电阻率（Rt）、声波时差（△t）、自然电位相对值（ASP）、自然伽玛相对值（△GR）、Sw一含水饱和度（Sw）、孔隙度（垂）等六种测井参数分别交会以确定鄂尔多斯盆地旦八区长4＋5储层的油层、油水层下限,该方法具有简单、实用、便于现场解释与判识的优点,并以正285井为例,说明解释结果和生产实际吻合程度较高。     

GPC: Use of automatic weighing to determine elution volumes

An automatic balance has been designed, constructed, and tested for continuous determination of the weight of the eluent in chromatography. This balance is considerably more precise than the frequently used automatic siphons. As the elution volume for any molecular species is independent of flow rate over a considerable range, the balance can be used with relatively inexpensive pumps, and thus highly precise constant volume pumps are not required.     

Design of electrochemical reactors via a sequential factorial costing technique

A simplified procedure for the design of electrochemical reactors based on Lang factors as a general strategy for assigning priorities in the assessment of costs and relative importance of process parameters is described. The importance of reactor geometry and its sensitivity to variation in cost components is illustrated by a specific industrial-scale design of a rotating bipolar cell equipped with wiper blades. The technique is applicable to any type of electrochemical cell.List of symbols a _c electrode cost per unit area of electrode - A _T total plant cost - A _S total plant cost, assuming standard materials and construction - C _c base delivery cost of a single cell - C _e cost of special machining and electrode materials per single cell - C _i installed capital cost - C _m base delivery cost of motors - C _o cost of major equipment made of standard material (carbon steel) - C _p base delivery cost of pumps - C _p1, C_p2 cost of a.c. power required for electrolyte circulation in the two RBE compartments - C _r base delivery cost of the total number of required rectifiers - C _rm cost of raw materials per annum - C _u cost of utilities per annum - d thickness of wiper blades in RBE cell - D _S total product cost per annum when plant is constructed with standard materials - D _t total product cost per annum - G dimension of gap between inner (RBE) and outer electrode - g acceleration due to gravity - I electric current flow - IC indirect costs - L _i ratio of installed capital cost to major equipment cost (Lang factor) - L length of the working electrode - L _o ratio of cost of system material to cost of standard material (Lang factor) - n number of electrolytic cells per reactor - P _mc power dissipated due to electrode rotation - P _mw power required to overcome fluid frictional forces at the wiper blades - P _pr energy imparted to electrolyte by each pump - P _rr total d.c. power requirement - (Re)_R radial Reynolds number (RBE radius as characteristic length)=2R ₁ ² - (Re) _z axial Reynolds number (gap between RBE and outer electrode as characteristic length)=2Gv _z/v - R ₁ radius of the RBE - (TGE) total general expenses - (TMC) total manufacturing cost - V _T compartment terminal voltage in RBE - v _Z axial flow velocity - w number of wiper blades (2 in RBE cell); and cell compartments - x _c actual cost of cell constructed from special alloy per base cost of cell - x _p actual cost of pumps constructed from special alloy per base cost of pumps - kinematic viscosity of electrolyte - v density of electrolyte - angular velocity of ratating electrode     

萃取条件对UHMWPE冻胶纤维结构与性能的影响

以二甲苯为萃取剂,对超高相对分子质量聚乙烯(UHMWPE)冻胶纤维中的溶剂进行萃取,研究了不同萃取条件下UHMWPE冻胶纤维的结构与性能。结果表明,UHMWPE冻胶纤维的最佳萃取条件为萃取时间5 min,萃取温度50℃。随着萃取温度的升高,UHMWPE冻胶纤维的强度和模量增大,萃取温度50℃时,其结晶度最大。经萃取干燥的UHMWPE冻胶纤维截面具有微孔的网状结构。     

Use of GPC-UV to determine the location of functional groups in styrenic polymers

Gel permeation chromatography (GPC) is one of the most important characterization tools of the polymer chemist. The coupling of GPC with ultraviolet (UV) spectroscopy (GPC–UV) increases the power of the tool even further. This article describes the use of GPC–UV to determine the location of functional groups in polymers. This information is important for characterization of functionalized polymers being used as building blocks for making block and graft copolymers, and for the elucidation of polymer degradation mechanisms. The use of GPC–UV for quantitation of the level of functional groups is hampered by the inability to achieve complete conversion of some UV transparent functional groups (e.g., hydroxyl and carbonyl) to the uniquely absorbing derivative needed for the analysis. Attempts to quantitatively derivatize polymer-bound functional groups using conditions developed for model compounds failed. However, the use of GPC–UV to locate functional groups in polymers (pendant vs. chain-end) is clearly demonstrated.     

Use of Dynamic Mechanical Measurements to determine the aging behavior of solid propellant

A process for determining the aging characteristics of solid rocket propellants by measuring their dynamic mechanical properties is described. Samples of rocket propellant are tested using a mechanical spectrometer at low strain levels and low frequencies. The change in the dynamic storage modulus of the propellant with aging time and temperature is used to determine the aging rate anf the likely mechanisms occuring during aging. The technique is advantageous is several respects:

• (1) because the tests are non-destructive and use small test specimens, and entire aging program can be conducted using much less propellant than is required ihn traditional aging programs (propellant requirements are reduced by more than an order of magnitude)
• (2) the technique can be applied to samples with unusual or unique geometries which cannot be tested using traditional methods;
• (3) test specimens can be obtained directly from live, operational solid rocket motors, and service life and mechanical property degradation can be determined.

     

Comparison of experimental solvent extraction techniques to determine the apparent composition of solvent refined coal

The apparent composition of Kentucky 9/14 solvent refined coal (SRC) has been determined by two Soxhlet solvent extraction techniques and one ultrasonic bath extraction technique. Each Soxhlet method gave significantly different composition results. Further, neither Soxhlet method gave results which agreed with data from the ambient temperature ultrasonic bath extractions. A third Soxhlet method involving reverse sequential extraction was found to be unsatisfactory for routine quantitative use because of excessive solvent loss and the possibility of sample repolymerization.     

A noninvasive technique to determine peripheral blood flow and heat generation in a human limb

The temperature at the surface of a human body is strongly related to heat generation in underlying tissue, and its perfusion by blood. The phenomena of heat generation and dissipation unfold the thermo-regulatory control of a human body. Excursions of body temperatures from “normal” have long been considered as evidence of ill health or abnormal physiological states. In this paper, a noninvasive technique is presented to determine the peripheral rates of heat generation and blood flow in a human limb from its recorded skin surface temperature. The technique involves an analysis based on calculus-of-variation, and features the well-known circadian cycle of mammalian body temperature. The method can readily be adapted to different body parts given appropriate heat transfer models. Further, the method may confirm or contribute to greater reliability of medical diagnosis of individuals for whom recorded skin surface temperatures are available. The technique is demonstrated for a set of skin surface temperature data.     

Ultrasonic technique to determine particle size and concentration in slurry systems

Acoustic velocity measurements have been used to estimate particle size and concentration in liquid-solid (LS) and gas-liquid-solid (GLS) systems. The slurries of 34 and particles and their binary mixtures in distilled water are tested in concentration range 2-10 vol% in batch operations. In GLS systems, the superficial gas velocity is varied from 0.03 to 0.10 m/s. The presence of gas bubbles affected the acoustic velocity measurements significantly. A data filtration procedure is developed to minimize the effect of gas phase and estimate variations in gas-free liquid-solid region. The filtered data are used to predict concentration using calibration equations and theoretical velocity prediction models of LS systems. The estimated concentrations are comparable with sedimentation-dispersion model predictions in GLS system. This technique is also used to predict average particle size and composition in binary mixtures of particles.     

膜分离技术改进红霉素提取工艺

引入超滤(UF)-纳滤(NF)组合膜分离技术代替板框过滤,对碱化红霉素发酵液进行提纯和浓缩。采用CA-30超滤膜和NF-250纳滤膜,研究了膜系统的通量、加水点、加水倍数和浓缩倍数等条件对膜的分离性能的影响。超滤加水倍数为2.0～2.3倍时,红霉素收率大于99%,膜通量为100 L/(m2.h)。通过萃取实验证明超滤能有效去除菌丝、蛋白等物质,滤液质量较好。纳滤浓缩倍数为4倍时,红霉素效价浓缩到6 500 U/mL左右,较板框滤液的效价高出40%,通量为20 L/(m2.h),纳滤收率为98.5%左右。UF-NF膜总收率为98%左右,比板框过滤提高4%～5%。     

应用膜分离技术改进林可霉素提炼工艺

介绍了在混合醇萃取前,引入超滤-纳滤组合膜分离技术对板框过滤后的林可霉素发酵液进行提纯和浓缩的小试结果：碱化料液的膜分离效果优于未碱化料液;对不同材料（PES、PS、PA）和相对截留分子质量的超滤和纳滤膜的筛选结果表明,PES-10和NF-270膜在膜通量和林可霉素收率、杂质去除等方面优于其他的膜,为最佳选择;超滤-纳滤后再进行萃取,不但混合醇的用量因料液体积减小而相应减少,并且萃取效率和产品收率都得到提高,当纳滤浓缩倍数为1.28时,一次萃取率和总收率分别比原来无超滤-纳滤时增加了4.3%和3.4%,所得萃取液的色度也较低.     

A sequential procedure to determine the number of breaks in trend with an integrated or stationary noise component

Perron and Yabu (2009a) consider the problem of testing for a break occurring at an unknown date in the trend function of a univariate time series when the noise component can be either stationary or integrated. This article extends their work by proposing a sequential test that allows one to test the null hypothesis of, say, l breaks versus the alternative hypothesis of (l + 1) breaks. The test enables consistent estimation of the number of breaks. In both stationary and integrated cases, it is shown that asymptotic critical values can be obtained from the relevant quantiles of the limit distribution of the test for a single break. Monte Carlo simulations suggest that the procedure works well in finite samples.     

Use of INT to determine the respiratory activity of immobilised and free Penicillium chrysogenum

The specific oxygen uptake rates (OUR) of k-carrageenan-immobilised and free cell cultures of Penicillium chrysogenum were determined using an oxygen electrode in a closed chamber. This was compared with the respiratory activity determined by the extent of staining with iodonitrophenyl tetrazolium chloride (INT). The degree of INT staining correlated with the OUR; an increase in INT deposition corresponding to an increase in the measured OUR. The INT staining technique could therefore be used to determine cell respiratory activity. In this way a profile of fungal cell activity throughout immobilised cell aggregates and free cell pellets was determined. In both types of cell culture, after the initial growth period only the peripheral biomass was observed to be active.     

Factors affecting oil extraction/water adsorption in sequential extraction processing of corn

The sequential extraction process (SEP) uses ethanol to extract oil and protein from cracked, flaked, and dried corn, and the dried corn simultaneously dehydrates the ethanol. Value-added co-products are possible, potentially making production of fuel ethanol more economical. The effects of solvent-to-corn (S/C) ratio, corn moisture content (MC), and number of extraction stages on ethanol drying, oil recovery, and protein loss during the simultaneous oil extraction/water adsorption step of SEP were evaluated. Extractions were carried out by using both aqueous ethanol and ethanol/hexane blends at 56°C. The S/C ratios tested were 3∶1, 2∶1 (control), 1.5∶1, and 1∶1 (w/w). More anhydrous ethanol, greater oil yields, and less co-extracted protein were obtained with higher S/C ratios. Less anhydrous ethanol and lower moisture adsorption capacities were obtained when the corn MC was ≥1.12%. Oil yields gradually decreased with drier corn, whereas protein loss increased when corn MC was <1.12%. Reducing the number of extraction stages from seven (original SEP) to five did not affect ethanol drying capability, oil yields, and protein co-extracted with oil. Using ethanol/hexane blends resulted in more anhydrous ethanol, higher oil yields, and less protein co-extracted with oil.