CO2动力学模型的比较

实验研究了850～1100℃下,稻草600℃焦、木屑500 ℃焦、宝雁煤、兖州煤和石油焦与CO2的气化反应,并分别采用了收缩未反应芯模型、混合模型和随机孔模型进行了反应速率实验数据的拟合.从数据拟合的吻合程度来看,随机孔模型与混合模型比收缩未反应芯模型拟合效果好,与其他两种模型相比,随机孔模型能够表达某些煤焦气化反应过程中出现最大反应速率的现象,这是由于随机孔模型考虑了气固相反应界面在反应过程中的变化,描述了煤焦在气化反应时微孔的发展与坍塌,比其他两种模型更准确、灵活.     

A 10 MV x-ray zero-area tissue-maximum ratio expression constructed by taking into account depth and off-axis beam quality change

A 10 MV x-ray zero-area TMR (tissue-maximum ratio) expression was constructed using an attenuation coefficient expression which is a function of depth (z) and off-axis distance (r). The zero-area TMR expression can take into account depth and off-axis beam quality change. The construction is based on a method of convolving one-dimension forward and backward primary dose-spread functions with the primary water collision kerma. Additional information required to construct the zero-area TMR expression for a given fanline at an off-axis distance of r is the zero-area TMR value at z = 0 [Ds(r)] and the v(r) and w(r) values in the backward primary dose-spread function. It was found that the depth of peak zero-area TMR [zpeak(r)] decreases with increasing r and that for large depths, the zero-area TMR expression changes significantly as a function of r. Obtaining an accurate expression for zero-area TMR is important for accurate construction of the three-dimensional (3D) forward and backward primary dose-spread functions needed for a 3D convolution method.     

The establishment of the I-PSS in the CIS countries taking into account its cultural and linguistic features. International Prostate Symptom Score

I-PSS adaptation to cultural and linguistic features of CIS population has been made in two stages. The 1st stage consisted of adaptation of the questionnaire's text and its check up by the specialists. At the 2nd stage a random sample of 46 males at the age 60 to 80 years were tested and retested. Reliability of the results has been proved in repeated tests and comparison of the adjusted questionnaire with its English-American variant. The authors propose to use adapted questionnaire I-PSS which meets international requirements in the countries members of CIS.     

Methods of evaluating processing ductility in pressure treatment powder metals. II. Fracture criteria taking into account the stress state

Conclusions In addition to the parameter of the stress state, the ductility of the porous metals is strongly effected by the initial porosity, dimensions, in the form of the pores, and the condition of interparticle contacts. These parameters must be reflected in the fracture criterion.In the literature dealing with the fracture of porous materials in hot deformation, the principal criterion used in this case is that proposed by Kh. A. Kun which is based on the critical ratio of the main strains on the surface of the processed material. However, this criterion does not make it possible to predict internal fracture and does not take into account the loading history under the parameter of the stressed state.In the approach to predicting the failure of a porous blank, based on the equation proposed by M. Oyane, the loading history, the effect of the stress state and the porosity of the material are taken into account. The criterion does not take into account the effect of the form of pores and of the state of interparticle contacts.By taking into account the structural parameters in the ductility theory of porous bodies, proposed in [9], it is possible to predict the moment of failure. However, the method of determining the coefficient which takes into account the structural parameters has not as yet been developed so that it is difficult to apply the approach in practice.Analysis of the state of work in the area of processing ductility of porous metals shows that at present there are no sufficiently reliable criteria of the fracture of porous metals in plastic deformation which would take into account all factors affecting the ductility and would be suitable for use in practice. This should be the subject of further investigations.Translated from Poroshkovaya Metallurgiya, No. 9(345), pp. 10–14,September, 1991.     

The HLA class I-CML association revisited taking into account the two forms of gene fusion in the Philadelphia chromosome. A multicenter study

CML patients possess either a b3-a2 or a b2-a2 fusion between the BCR and ABL genes. Depending on the type of fusion, two different series of non-self potentially immunogenic peptides may be produced. If they are presented by HLA class I molecules and recognized by cytotoxic CD8 lymphocytes, individuals could be more susceptible or resistant to leukemic cells bearing one or the other form of fusion according to their HLA class I phenotype. To test this point, the frequencies of HLA-A and HLA-B alleles were compared between b3-a2 and the b2-a2 CML patients. In essence, no difference was found whose significance could withstand correction for multiple comparisons.     

转炉喷吹CO2+O2混合气体基础研究

通过对转炉喷吹CO_2+O_2混合气体的热力学分析,结合实验室模拟转炉吹炼末期喷吹CO_2+O_2实验结果,探讨了在顶吹转炉中应用CO_2+O_2进行脱碳抑氧的可行性。得出结论,混合气体中CO_2比例增大,碳氧积降低,枪位对碳氧积的影响减弱,但回磷量增加,当CO_2比例增大到CO_2:O_2=1:1时,顶吹转炉碳氧积可控制在0.23×10-6~0.25×10-6,平均回磷量0.001%,混合气体中CO_2最大理论比例可增加到79.1%。     

Temperature changes in a model of the rabbit's body under extreme cooling taking into account the effect of Arrhenius' law on the intensity of heat production

A device automatically regulating the intensity of heating when simulating the metabolism level in the rabbit heat-physical model, was compared with the similar results obtained in live rabbits. The results coinciding quite well, the findings suggest that the model's behaviour is quite adequate in experiments with profound cooling.     

Model for the interaction of the melt components of metals and slag systems that takes into account their cluster structure

The cluster structure of liquid metals and slag systems is thermodynamically described at the electronic level of unit elements. A model developed on this basis is used to study the dependence of the nitrogen solubility in steel and to calculate the dynamic viscosity and electrical conductivity of manganese ferroalloy systems.     

Src homology-2 domains: structure, mechanisms, and drug discovery

The purpose of this study was to examine the trainability of anticipation in intermediate tennis players. In particular, the study examined whether video presentations could improve on-court tennis serve returns. A series of separate A-B designs across 6 participants was implemented, with baseline and intervention scores for on-court serve-return performance being recorded. Intervention consisted of 2 phases: a training phase and an on-court testing phase. The training phase, which employed a changing criterion design, consisted of a series of tennis-serve video presentations that were replayed with gradually increasing speed. All serves were occluded on racquet/ball contact, and participants were asked to predict the type, depth, and width of the serve. Following completion of the training phase, participants were again tested on their ability to return tennis serves on the tennis court. On-court results suggested that anticipation ability and performance did improve as a result of the intervention.     

Models of calcium activation account for differences between skeletal and cardiac force redevelopment kinetics

To explain observed differences in the activation dependence of force redevelopment kinetics between cardiac and skeletal muscle, two numerical models of contractile regulation by Ca2+ were investigated. Ca2+ binding and force production were each modelled as two-state processes with forward and reverse rate constants taken from the literature. The first model incorporates four possible thin-filament states. In the second model Ca2+ is assumed not to dissociate from a thin-filament unit in the force-generating state, resulting in three states. The four-state model can account for the activation dependence of the rate constant of tension redevelopment (ktr) seen in skeletal muscle, without requiring that Ca2+ directly modulates the kinetics of any step in the cross-bridge cycle. Using identical kinetic parameters, the three-state model shows no activation dependence of ktr, consistent with our results in cardiac muscle. Following a step increase in [Ca2+], the rate of rise in tension (as described by the rate constant kCa) varies with the final [Ca2+] for both models, consistent with experimental results from skeletal and cardiac muscle. These numerical models demonstrate that experimental measurements thought to reveal changes in kinetic parameters may simply reflect coupling between the two kinetic processes of Ca2+ binding and force generation. Furthermore, the models present possible differences in the Ca2+ activation scheme between cardiac and skeletal muscle which can account for the contrasting activation dependencies of force redevelopment kinetics.     

Nonuniformity of NaOH concentration and effective bubble diameter in CO2 injection into aqueous NaOH solution

Mixed CO₂-N₂ gas was blown into an aqueous NaOH solution through a submerged nozzle of 3 mm ID, and the net absorption rate of CO₂ from the gas bubbles during their ascent was determined. The size distribution and the rising velocity of bubbles were also measured. The enhancement factor was estimated from the reported reaction rate constant as 1.16 to 8.20 at the NaOH concentration from 0.01 to 0.3 mol · dm^-3. It was deduced that NaOH concentration in the plume zone in which gas bubbles ascended was markedly lower than that of the bulk solution when NaOH concentration of the bulk solution was lower than 0.1 mol · dm^-3. The measured size distribution of bubbles had two peaks at approximately 0.15 and 2.3 cm. However, the effective bubble diameter defined as mean diameter based on the amount of absorbed CO₂ was 2.3 cm and it was close to the mean of larger bubbles.     

The molecular mechanisms of 5-fluoro-2'-deoxyuridine induced cell death

The molecular mechanism of cell death induced by 5-Fluoro-2'-deoxyuridine (FUdR) was investigated. FUdR caused cell death to induce dNTP pool imbalance and following DNA double strand breaks in mouse mammary tumor FM3A cells. We isolated a new endonuclease from FUdR-treated cells, named endonuclease S, that played an important role in FUdR-induced cell death. Cells treated with FUdR showed intracellular acidification before cell death formation. We observed that the endonuclease S in acidic cells may lead the DNA fragmentation. On the other hand, we observed that protease inhibitors (such as TLCK, TPCK, PMSF, p-APMSF, Pefabloc SC and Z-Asp-CH2-DCB) blocked intracellular acidification, DNA fragmentation and FUdR-induced cell death. But the inhibitors did not affect dNTP pool imbalance in the cells. These results suggest that proteases act at the point of downstream of dNTP pool imbalance and upstream of the intracellular acidification.