蒸汽喷射泵超音速流体三维模拟研究

利用大型流体力学软件FLUENT，对不同结构尺寸和边界条件的蒸汽喷射泵喷嘴内超音速流场进行了3D模拟。探讨了流场内压力和速度的相互作用及其分布规律；讨论了热力学参数和几何参数对流场特性的影响规律；并分析了喷嘴内影响喷射器性能的激波产生的因素。基本上与Dayton和石井博的研究结果一致。     

LDA端泵浦短腔Cr^4＋：YAG被动调Q Nd：YAG激光器

采用峰值功率600W的准连续（QCW）激光二极管阵列（LDA）端泵浦Nd:YAG晶体，其耦合装置为自制的微柱透镜阵列和透镜导管，使用Cr^4 :YAG可饱和吸收晶体作为Q开关，并选取长度较短的Nd:YAG晶体，从而使激光腔的长度缩短到11mm，实验研究了在较短的腔长条件下调Q输出多脉波形的时间、空间分布，采用平－平腔结构时，每次泵浦脉冲获得单脉冲输出，脉冲宽度＜4ns，能量4．5mJ。     

Dietary quercetin, immune functions and colonic carcinogenesis in rats

Rats fed 100 mg/kg quercetin (QUE) daily for 7 weeks had significantly enhanced natural killer cell activity compared to their vehicle (VEH)-fed control. In contrast, rats fed 100 mg/kg QUE and treated with the colon carcinogen, azoxymethane had significantly reduced natural killer cell activity compared to their VEH-fed azoxymethane-treated control. There was no significant difference in natural killer cell activity between the two control groups. Antibody production and delayed-type hypersensitivity were not altered by QUE feeding in any treatment group. In vitro exposure of splenic natural killer cells to 1mM QUE significantly decreased natural killer cell cytotoxicity. Lower QUE concentrations produced a non-significant reduction in natural killer cell activity that was restored to control values at 1 x 10(-13)M QUE. The distribution, multiplicity and total number of colonic preneoplastic lesions, aberrant crypt foci, was not significantly different in the QUE-fed azoxymethane-treated rats when compared to azoxymethane-treated vehicle-fed rats at the conclusion of 7 week feeding period. We found no correlation between immune function and development of preneoplastic colon lesions in this study.     

Pulmonary delivery of nanoparticles of insoluble, iodinated CT X-ray contrast agents to lung draining lymph nodes in dogs

Lung cancer continues to be a leading cause of death around the world. Staging of this disease is critically dependent upon the involvement or noninvolvement of the lymph nodes which drain the region of lung containing the lesion/tumor. Palpation, unenhanced CT, and lymph node excision (i.e., mediastinectomy) are currently used to ascertain the status of these regional draining lymph nodes. The work reported herein details the first efforts toward the pulmonary instillation of iodinated nanoparticles for contrast-enhanced CT of lung draining lymph nodes. The data reflect the impact of dose, time post instillation, and formulation (surfactant) upon the observed CT enhancement of the tracheobronchial lymph nodes of beagle dogs. In addition, initial safety is discussed with both macroscopic and microscopic observations. The results indicate that pulmonary instillation of small volumes of iodinated nanoparticles could be successfully used to aid staging of lung cancer by CT imaging.     

Assessing alcohol problems in female DWI offenders

The severity of alcohol problems in a sample of 812 women driving while intoxicated (DWI) offenders enrolled in a Drinking Driver Program in New York State was assessed through the use of multiple measures. These women voluntarily provided information through a self-administered questionnaire completed at the beginning of the program. Classification of alcohol problems based on DSM-III-R criteria was compared with classification based on the use of alcohol-specific and nonalcohol-specific measures of alcohol-related problems. Greater hostility and a larger number of drinks ever consumed accounted for nearly 12% of the variance between no diagnosis and alcohol abuse women, whereas these two variables plus age, race, depression, and having a relative with alcohol problems accounted for nearly 41% of the variance between alcohol abuse and dependent women. A subsample of women within each DSM-III-R diagnostic group showed high risk for later, more severe alcohol problems. Multiple measures of alcohol problems help to elucidate subtle differences in alcohol problems within each of the broad categories specified by the DSM, and should facilitate more appropriate intervention and treatment plans for women DWI offenders with alcohol-related problems.     

Ambient, biological, and biological effect monitoring of exposure to polycyclic aromatic hydrocarbons (PAHs)

A novel strategy was utilised to assess the risk to health from exposure to polycyclic aromatic hydrocarbons (PAHs). Ambient monitoring was carried out by personal sampling. Urinary thioethers (UTh) and urinary 1-hydroxypyrene (1-HP) were utilised for biological monitoring. Urinary d-glucaric acid (UDGA) and sister chromatid exchange (SCE) in peripheral blood lymphocytes were used as biological effect markers. The population was categorised into exposed and control groups according to the external dose of PAHs. The excretion of 1-HP in the controls over the 3-day period showed a relatively stable baseline, while the exposed showed a significant increase over the same period of time. SCE frequency in the exposed population was significantly different from controls.     

Effects of the Na+/H+-exchange inhibitor Hoe 642 on intracellular pH, calcium and sodium in isolated rat ventricular myocytes

The inhibitors of the Na+/H+-exchange (NHE1) system Hoe 694 and Hoe 642 possess cardioprotective effects in ischaemia/reperfusion. It is assumed that these effects are due to the prevention of intracellular sodium (Nai) and calcium (Cai) overload. The purpose of the present study was to investigate the effects of Hoe 642 on intracellular pH, Na+ and Ca2+ (pHi, Nai and Cai) in isolated rat ventricular myocytes under anoxic conditions or in cells in which oxidative phosphorylation had been inhibited by 1.5 mmol/l cyanide. In cells which were dually loaded with the fluorescent dyes 2, 7-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) and Fura-2, anoxia caused acidification of the cells (from pHi 7.2 to pHi 6.8) and an increase in Cai from about 50 nmol/l to about 1 micromol/l. The decrease in pHi began before the cells underwent hypoxic (rigor) contracture, whereas Cai only began to rise after rigor shortening had taken place. After reoxygenation, pHi returned to its control value and Cai oscillated and then declined to resting levels. It was during this phase that the cells rounded up (hypercontracture). When 10 micromol/l Hoe 642 was present from the beginning of the experiment, pHi and Cai were not significantly different from control experiments. At reoxygenation, pHi did not recover, but Cai oscillated and returned to its resting level. To monitor Nai, the cells were loaded with the dye SBFI. After adding 1.5 mmol/l cyanide or 100 micromol/l ouabain, Nai increased from the initial 8 mmol/l to approximately 16 mmol/l. Hoe 642 or Hoe 694 (10 micromol/l) did not prevent the increase in Nai. In contrast, the blocker of the persistent Na+ current R56865 (10 micromol/l) attenuated the CN--induced rise in Nai. The substance ethylisopropylamiloride was not used because it augmented considerably the intensity of the 380 nm wavelength of the cell's autofluorescence. In conclusion, the specific NHE1 inhibitor Hoe 642 did not attenuate anoxia-induced Cai overload, nor CN--induced Nai and Cai overload. Hoe 642 prevented the recovery of pHi from anoxic acidification. This low pHi maintained after reoxygenation may be cardioprotective. Other possible mechanisms of NHE1 inhibitors, such as prevention of Ca2+ overload in mitochondria, cannot be ruled out. The increase in Nai during anoxia is possibly due to an influx of Na+ via persistent Na+ channels.     

Novel sequence organization and insertion specificity of IS605 and IS606: chimaeric transposable elements of Helicobacter pylori

We have used PKH26 dye, which is incorporated stably into the membrane of cells, to determine, using flow cytometry, lymphocyte proliferative responses to the antigen tetanus toxoid in fresh and cryopreserved samples. Measuring cell proliferation with this dye has advantages over either 3H-thymidine or Bromodeoxyuridine (BrdU). Whereas the existing methods measure proliferation at a single time point, PKH26 gives a cumulative measure of cell proliferation. As PKH26 is incorporated into the cell membrane, cells do not have to be permeabilised to allow dye incorporation into a cytoplasmic compartment. Most importantly, PKH26 can be used in combination with monoclonal antibodies to surface markers on mixed populations of cells, to determine the proliferation of individual subpopulations, without the need for prior cell fractionation. We also show that PKH26 can be used with similar efficacy in both fresh and cryopreserved samples. In addition since PKH26 is a cumulative measure of proliferative responses we were able to show that restimulation of the dividing population in vitro with fresh antigen presenting cells (APC) and antigen permits characterisation of a further proliferating cell population. The use of PKH26 dye in combination with cell phenotyping and measurement of cytokine production at the single cell level will prove a powerful tool for multiparameter analyses of cellular responses to antigen.     

Quantification of creatinine kinetic parameters in patients with acute renal failure

BACKGROUND: Urea kinetic modeling (UKM) and creatinine (Cr) kinetic modeling (CKM) are used in the nutritional evaluation of end-stage renal disease (ESRD) patients. Both the UKM-derived normalized protein catabolic rate (nPCR) and the CKM-derived estimate of lean body mass (LBM) may also provide important information in critically ill acute renal failure (ARF) patients. Estimation of LBM may be particularly useful as previous data demonstrate that malnutrition adversely influences outcome in ARF patients. METHODS: Eleven critically ill ARF patients (age 52 +/- 21 years; mean +/- SD) treated with continuous venovenous hemofiltration (CVVH) were the study group. They were analyzed at steady state with a single-pool variable-volume model that determined the creatinine generation rate (GCr) by a methodology that we have previously described. RESULTS: The CVVH ultrafiltrate production rate was 913 +/- 49 ml/hr, yielding a blood Cr clearance of 15.2 +/- 0.9 ml/min and a steady state serum Cr of 3.4 +/- 1.7 mg/dl. Daily creatinine generation normalized to body wt (creatinine index: CI) was 6.3 +/- 0.8 and 10.6 +/- 3.0 mg/kg/day for females (N = 4) and males (N = 7), respectively (P < 0.05). Estimated mean LBM was 30.0 +/- 2.0 and 41.2 +/- 7.0 kg in females and males, respectively (P < 0.05), while the same parameter normalized to body wt was 0.50 +/- 0.05 and 0.52 +/- 0.10, respectively. These values are substantially lower than those previously reported for both normal and ESRD patients. Regression analysis demonstrated both GCr (r2 = 0.96; P < 0.001) and LBM (r2 = 0.96; P < 0.001) were significantly correlated with steady state serum Cr in a linear manner. However, no significant correlation (r2 = 0.06; P = 0.24) between nPCR and CI was observed. CONCLUSIONS: These data suggest critically ill ARF patients have severe somatic protein depletion. This malnourished state is likely due to deficits established prior to the development of ARF, such as those secondary to underlying chronic illnesses or prolonged hospitalization, and deficits related to acute hypercatabolism. Quantitative assessment of malnutrition in ARF patients with this CKM-based methodology may permit a better understanding of predisposing factors and, consequently, facilitate the development of interventions designed to prevent malnutrition in these patients.     

Experience in the study of the effects of lead on the health status of children in Belovo]

Lead releases in Belovo town containing metallurgy enterprise had reached 120 tons/year earlier, but in recent years have decreased to 9 tons/year. Reduction of the production induced decrease of lead levels in the ambient air from 0.7-2.3 mg/m3 in 1994 to 0.001-0.24 mg/m3. Lead concentration in the soil ranges from 30 to 3000 mg/kg. Lead levels were measured in serum of 91 children, in hair of 67 ones and in teeth of 15 children. Serum lead levels in children aged 7-8 years varied from 0.5 to 39 mg/dl, with an average of 9.9 mg/dl (SD is 5.2 mg/dl), geometric mean is 8.5 mg/dl and error of geometric mean is 3.3. 46% of the children had serum lead levels exceeding the normal one (10 mg/dl). Average lead level in the hair equaled 4.5 mg/g (SD is 4.9 mg/g). The children living in towns with higher environmental lead levels demonstrated more frequent anxiety and changes in higher psychic functions. The major points influencing the serum lead level are proximity to highway, dietary load of goods grown near the residence, mother's smoking. Biokinetic model describing lead transfer into the blood helped to evaluate various modes of the enterprise functioning and efficiency of some environmental protection measures. The most efficient are measures aimed to lower dietary intake of lead, less efficiency is associated with measures reducing lead levels in air, dust and soil.