高炉型熔渣中TiO2的活度

在1500℃下用金属Sn作熔剂,石墨作还原剂,采用“熔渣—金属Sn”化学平衡法和相图计算法,得到了高炉型熔渣中TiO_2的活度,并讨论了渣中TiO_2的活度和活度系数随其浓度变化的规律。     

Cocaprins, β-Trefoil Fold Inhibitors of Cysteine and Aspartic Proteases from Coprinopsis cinerea

We introduce a new family of fungal protease inhibitors with β-trefoil fold from the mushroom Coprinopsis cinerea, named cocaprins, which inhibit both cysteine and aspartic proteases. Two cocaprin-encoding genes are differentially expressed in fungal tissues. One is highly transcribed in vegetative mycelium and the other in the stipes of mature fruiting bodies. Cocaprins are small proteins (15 kDa) with acidic isoelectric points that form dimers. The three-dimensional structure of cocaprin 1 showed similarity to fungal β-trefoil lectins. Cocaprins inhibit plant C1 family cysteine proteases with K_i in the micromolar range, but do not inhibit the C13 family protease legumain, which distinguishes them from mycocypins. Cocaprins also inhibit the aspartic protease pepsin with K_i in the low micromolar range. Mutagenesis revealed that the β2-β3 loop is involved in the inhibition of cysteine proteases and that the inhibitory reactive sites for aspartic and cysteine proteases are located at different positions on the protein. Their biological function is thought to be the regulation of endogenous proteolytic activities or in defense against fungal antagonists. Cocaprins are the first characterized aspartic protease inhibitors with β-trefoil fold from fungi, and demonstrate the incredible plasticity of loop functionalization in fungal proteins with β-trefoil fold.     

Virtual approach to holonic control of the tyre-manufacturing system

Tyre manufacturers aiming to remain competitive in complex modern markets must promptly adjust to the changes within the production environment. With traditional tyre-manufacturing systems, a slow response during optimization of the manufacturing process and low-level adaptability to system disturbances is evident. The presented approach to virtual holonic control of the tyre-manufacturing system enables dynamic response in the event of new optimization demands, decrease of the impact of disturbances on system productivity and smaller future investments in the manufacturing equipment.     

The effect of pyridine ring functionalization on the conductivity of crosslinked CO-poly(styrene-4-vinylpyridine) derivatives

The effect of pyridine ring functionalization in crosslinked co-poly(styrene-4-vinylpyridine) on electrochemical behavior was studied using impedance spectroscopy. The introduction of a substituent on the nitrogen atom increases conductivity from 10^-14 to around 10^-11 Scm^-1 at room temperature, but the effect of the substituent becomes more evident at 64°C, at which the n-butyl derivative (co-poly[styrene-[4-vinyl(N-butylpyridinium bromide)]])-(3) has a higher conductivity (ω = 7 × 10⁻¹⁰ Scm⁻¹) than the hydrogen analog (co-poly[styrene-[4-vinyl(pyridinium bromide)]])-(2) (ω = 4.3 × 10⁻¹⁰ Scm⁻¹), while the iodo derivative (co-poly[styrene-[4-vinyl(N-iodopyridinium bromide)]])-(6) has a conductivity ten times lower. Further increase in the conductivity was observed upon the substitution of the bromine anion with the three-bromide anion (Br₃)⁻, but the effect depends on the substituent on the nitrogen atom: 4.4 times higher conductivity was found for the hydrogen pyridinium salt (4) in comparison with sample (2), and the conductivity increases 30-fold for the N-butyl derivative (5) compared with sample (3). The conductivity increased exponentially with temperature and the activation energy values vary from 0.76 to 1.01 eV. Impedance responses for dried samples of pyridinium salts (2), (3), (4), (5), and (6) suggested electron-type conductivity. The conductivity of crosslinked polymers depends very much on the conditions, and increases by several orders of magnitude when water or methanol is present in the atmosphere during measurement. The conductivity also depends on the structure of the substituent attached to the nitrogen atom: ω = 5 × 10⁻⁴ Scm⁻¹ and ω = 2 × 10⁻⁴ Scm⁻¹ for hydrogen bromide (2) and N-butyl bromide derivative (3), but the conductivity of the N-iodo derivative (6) changed very little. In contrast, the impedance responses for samples stored in the presence of water or methanol suggested ion conductivity. © 1996 John Wiley & Sons, Inc.     

Voluntary pacing and energy cost of off-road cycling and running

PURPOSE: The purposes of this study were (1) to compare self-chosen speed of off-road cyclists and runners on a hilly course, (2) to compare the energy expenditure of off-road cyclists and runners on the same terrain, and (3) to describe changes in energy expenditure over the course of the exercise period. METHODS: Runners and cyclists performed three laps on a 2.75 km gravel course in a single exercise bout. The course was divided into 13 segments differing in grade and length. Position on the course and heart rate were recorded every few seconds. Speed was computed for each course segment on each lap; energy expenditure was estimated using recorded heart rates and exercise-specific maximal oxygen uptake measurements made prior to participation in the study. RESULTS: There were significant relationships between grade and speed for both runners (r = 0.64) and cyclists (r = 0.44). The differences between cyclists and runners were greatest on downhill segments. Energy expenditure rates were not significantly different for runners (71.6% VO2 peak) and cyclists (68.5% VO2 peak). CONCLUSIONS: Off-road cycling and running are comparable in energy demands. Variation in skill levels may account for the increased variability in speed among cyclists on downhill terrain.     

Tension and compression testing of single-crystalline gamma Ti-55.5 pct Al

High-quality single crystals 6 to 10 mm in diameter of γ-Ti 55.5 pct Al have been grown using the optical float zone furnace technique. These crystals have been oriented and cut into microsample tension and compression specimens with a gage area of 250×250 μm and an effective gage length of 300 μm. These specimens have been deformed using a microsample testing machine which applies loads on the order of 50 N and measures strain using an interferometric strain/displacement gage. Stress-strain curves have been obtained for four different orientations and two temperatures and as a function of the sense of the applied load. Of special interest is the availability of tensile data for the resolved shear stress. Preliminary comparison of tension and compression microsample tests indicates that the tension-compression asymmetry is negligible at 500 K. This article is based on a presentation made in the symposium “Fundamentals of Gamma Titanium Aluminides,” presented at the TMS Annual Meeting, February 10–12, 1997, Orlando, Florida, under the auspices of the ASM/MSD Flow & Fracture and Phase Transformations Committees.     

Upper limb motion analysis using haptic interface

An objective test for evaluating the functional studies of the upper limbs (UL) in patients with neurological diseases (ND) is presented. The method allows assessment of kinematic and dynamic motor abilities of UL. Our methodology is based on creating a virtual environment, using a computer display for visual information and a PHANTOM haptic interface. The haptic interface is used as a kinematic measuring device and for providing tactile feedback to the patient. In virtual environment, a labyrinth in patient's frontal plane was created at the start of each test. By moving the haptic interface control stick the patient was able to move the pointer (a ball) through the labyrinth in three dimensions and to feel the reactive forces of the wall. The new test offers a wide range of numerical and graphic results. It has so far been applied to 13 subjects with various forms of ND (e.g., Friedreich Ataxia, Parkinson's disease, Multiple Sclerosis) as well as to healthy subjects. The comparison in performance between right and left UL has been carried out in healthy subjects     

Cyclic Adenosine Monophosphate Eliminates Sex Differences in Estradiol-Induced Elastin Production from Engineered Dermal Substitutes

Lack of adult cells’ ability to produce sufficient amounts of elastin and assemble functional elastic fibers is an issue for creating skin substitutes that closely match native skin properties. The effects of female sex hormones, primarily estrogen, have been studied due to the known effects on elastin post-menopause, thus have primarily included older mostly female populations. In this study, we examined the effects of female sex hormones on the synthesis of elastin by female and male human dermal fibroblasts in engineered dermal substitutes. Differences between the sexes were observed with 17β-estradiol treatment alone stimulating elastin synthesis in female substitutes but not male. TGF-β levels were significantly higher in male dermal substitutes than female dermal substitutes and the levels did not change with 17β-estradiol treatment. The male dermal substitutes had a 1.5-fold increase in cAMP concentration in the presence of 17β-estradiol compared to no hormone controls, while cAMP concentrations remained constant in the female substitutes. When cAMP was added in addition to 17β-estradiol and progesterone in the culture medium, the sex differences were eliminated, and elastin synthesis was upregulated by 2-fold in both male and female dermal substitutes. These conditions alone did not result in functionally significant amounts of elastin or complete elastic fibers. The findings presented provide insights into differences between male and female cells in response to female sex steroid hormones and the involvement of the cAMP pathway in elastin synthesis. Further explorations into the signaling pathways may identify better targets to promote elastic fiber synthesis in skin substitutes.     

用D-最优设计合成渣系进行铁水同时脱磷脱硫

运用D-最优设计的二次对数多项式四分量混料模型,完全以工业原料和废料合成渣剂,在1300 ℃进行800 g铁水预处理同时进行脱磷、脱硫,脱磷率与脱硫率分别可达58％和86％,硫可降至0.004％。并用计算机回归出脱磷率和脱硫率与渣剂组成的关系式,该关系式对实际操作具有一定的指导意义。