高焓超声速载气的产生

本文所做的工作，是为研究与探索乙烯新工艺－气动加热裂解法制取乙烯作铺垫。其任务是设计并加工一套燃气发生器系统以产生高焓超声速载气。这里所说的载气，其成分实际上就是水蒸气。从化学动力学的角度察看热裂解制取乙烯这一化学反应，为提高乙烯的单程产率，必须为原料气的裂解反应创造所需的高温条件，相应缩短原料气在高温的驻留时间。但是，目前的竖管式裂解炉制取乙烯工艺，由于采用炉管外加热，工艺受炉管的材料、传热等性能的，因此原料气的反应湿度并未达到高乙烯产率所要求的裂解温度，并且反应停留时间过长。在探索如何提高乙烯的单程产率这一问题上，气动加热裂解法可以说是一重要里程碑。新方法提出了一全新概念：让反应气流通过强激波，气流通过激波后由于其温度的急剧升高而发生热裂解。此方法的关键问题是：（1）如何使反应气流产生强激波而进行自加热；（2）如何合理控制反应气流的裂解反应时间，即其驻留高温状态的时间。针对第一个问题，解决的方案是以高焓声速载气（即水蒸气）与反应气流进行混合，以提高反应气流的速度与温度。本文的工作，集中在如何产生高焓水蒸气这一问题上。其主要任务，就是设计与加工一套以氢气与氧气为燃料与氧化剂的燃气发生器系统。本文主要概括论述了其中一的些关键性问题：（1）氢气与氧气的流量与混合比的控制。组合使用稳压阀（或稳压器）与临界流量喷管，以控制氢氧流量及其混合比。（2）燃烧室燃气温度的控制。由于氢氧直接燃烧后产生的水蒸气温度太高；同时乙烯裂解试验方案要求载气温度具有可调节性，这就要求燃气发生器产生的水蒸气其温度在一定范围内可调控。采取的方案是向燃烧室喷入水雾，藉以控制燃气温度。（3）燃烧室压力控制。与燃气的温度必须具有可调节性要求一样，乙燃总体试验方案要求其压力也具有可调节性。采取的方案有两种：首先是调节氢氧配气系统中汇流排的总压值以改变氢氧各自的流量，从而达到改变燃烧室的燃烧压力；其次，调节尾喷管喉道的大小可以达到改变燃烧室压力的目的。（4）点火与燃烧稳定性。采用加热电阻丝的点火方案。实验表明，低压状态（小于10大气压）下氢氧燃烧稳定性没有太大问题。在设计的燃气发生器上，我们分别适当改变了供气参数（主要是压力参数）与尾喷管喉道面积以察看各种工况下燃气发生器的工作情况；测定了燃烧室内燃气的压力参数的改变趋势，并根据燃气的流量与压力对燃气的温度进行了估算，从中得出一些基本结论：（1）尾喷管喉道面积减小时，燃烧室的压力将增大。在未改变氢氧供气来流的情况下，燃烧室压力与尾喷管喉道面积基本成反比关系；同时，随着燃烧室压力的增大，燃气的温度略有所降低。（2）继续减小尾喷管喉道面积，由于燃烧室压力的增大，这将破坏供气系统中临界喷管的临界工作状态，从而改变（减小）氢氧的来流流量、并很有可能破坏氢氧的化学当量配比，这将彻底改变燃气的成分与温度。（3）增加氢氧的来流压力时，燃烧室压力将增大，同时燃气温度也有明显增加；燃烧室压力与尾喷管喉道面积仍然呈反比关系，但两者乘积值将增大。（4）燃烧室压力较小时，燃烧现象有高频的振荡，但压力振幅较小；当尾喷管面积减小而导致燃烧室压力增大时，燃烧振荡将由高频转为低频，同时压力振幅增大。锅炉、卵石床都能产生高焓水蒸气。由于总体方案要求的水蒸气流量小，与其它方法相比，以氢氧燃烧的方法产生的水蒸气，其温度更高、更符合乙烯总体方案的要求，温度、压力等参数的调节方便，而且相对而言设备较为简单，是一种切实可的方案。

Dieta hiperlipídica compromete a morfologia e alguns parâmetros funcionais de testículo e tireóide de ratos jovens

Estudos demonstram que o sobrepeso e a obesidade podem afetar a fertilidade masculina. Além disso, a função tireóidea também esta associada à alteração da função testicular, entretanto, o papel fisiológico dos hormônios tireoideanos na regulação do sistema reprodutor masculino ainda não esta claro. Aos 21 dias de idade, ratos machos receberam uma dieta manipulada contendo diferentes concentrações de óleo de soja até a idade de 30 e 60 dias, os grupos controle (C30, n=6 e C60, n=6), receberam dieta contendo 7% e os grupos hiperlipídicos (HL30, n=6 e HL60, n=6), receberam dieta contendo 19% deste óleo. Ao final de cada período, os animais foram avaliados por DXA (Absorciometria de Raios-x em Duas Energias) e sacrificados por exsanguinação. Para avaliar alterações na estrutura dos tecidos testicular e tireóideo, foram realizados a morfologia e a estereologia. No plasma, para determinar os perfis bioquímico e hormonal, foram avaliados, triglicerídeos, colesterol total, HDL-colesterol, VLDL, glicose e albumina, por métodos colorimétricos e leptina, insulina, T4, T3, TSH e testosterona por radioimunoensaio (RIE). Para evidenciar a expressão de receptor androgênico (AR) em testículos, foi realizado imunomarcação, com anti-AR. Durante todo o período experimental, foram analisados a massa corporal, a ingestão alimentar e o comprimento corporal, os quais permaneceram inalterados. No grupo HL, a massa magra foi menor aos 30 dias, já a gordura corporal total foi maior no mesmo grupo, aos 60 dias nenhuma diferença foi notada entre os grupos. No grupo HL30 não houve diferença quanto à massa dos tecidos, já no grupo HL60, o peso do epidídimo, fígado e gordura visceral mantiveram-se aumentados. No grupo HL30 não houve diferença em relação ao perfil bioquímico, já no grupo HL60, os níveis de glicose, mantiveram-se altos. Quanto às dosagens hormonais no grupo HL30, TSH e leptina estiveram aumentados e T3 reduzido, e no grupo HL60, T3 e leptina estiveram aumentados. Os dados morfométricos e estereológicos de testículo no grupo HL30 mostram aumento no número de túbulos seminíferos e da densidade de comprimento (Lv), já no grupo HL60, há redução no número de túbulos seminíferos e no diâmetro do mesmo. Quanto à expressão de receptor androgênico nas células testiculares, não parece haver diferença entre os grupos independente da idade de consumo da dieta. A dieta hiperlipídica promoveu alterações metabólicas aos 30 dias e modificações na morfologia do tecido tireoidiano e testicular em ambas as idades, o que indica reflexos na função reprodutora.

Instalação de antivírus na servidora de mail: uma opção para impedir ataques de vírus anexados a e-mail.

Antivírus no servidor de mail. Configuração de antivírus na máquina servidora de mail. Funcionamento do programa responsável pela entrega e recebimento de mail - Sendmail. Procmail. Amavis.

France and the Problems of Security and Disarmament after the First World War

Jackson, Peter, 'France and the Problems of Security and Disarmament after the First World War', Journal of Strategic Studies (2006) 29(2) pp.247-280 Special Issue: Enforcing arms limits: Germany post 1919; Iraq post 1991 RAE2008

Bacteria localization and chorion thinning among preterm premature rupture of membranes.

OBJECTIVE: Bacterial colonization of the fetal membranes and its role in pathogenesis of membrane rupture is poorly understood. Prior retrospective work revealed chorion layer thinning in preterm premature rupture of membranes (PPROM) subjects. Our objective was to prospectively examine fetal membrane chorion thinning and to correlate to bacterial presence in PPROM, preterm, and term subjects. STUDY DESIGN: Paired membrane samples (membrane rupture and membrane distant) were prospectively collected from: PPROM = 14, preterm labor (PTL = 8), preterm no labor (PTNL = 8), term labor (TL = 10), and term no labor (TNL = 8), subjects. Sections were probed with cytokeratin to identify fetal trophoblast layer of the chorion using immunohistochemistry. Fluorescence in situ hybridization was performed using broad range 16 s ribosomal RNA probe. Images were evaluated, chorion and choriodecidua were measured, and bacterial fluorescence scored. Chorion thinning and bacterial presence were compared among and between groups using Student's t-test, linear mixed effect model, and Poisson regression model (SAS Cary, NC). RESULTS: In all groups, the fetal chorion cellular layer was thinner at rupture compared to distant site (147.2 vs. 253.7 µm, p<0.0001). Further, chorion thinning was greatest among PPROM subjects compared to all other groups combined, regardless of site sampled [PPROM(114.9) vs. PTL(246.0) vs. PTNL(200.8) vs. TL(217.9) vs. TNL(246.5)]. Bacteria counts were highest among PPROM subjects compared to all other groups regardless of site sampled or histologic infection [PPROM(31) vs. PTL(9) vs. PTNL(7) vs. TL(7) vs. TNL(6)]. Among all subjects at both sites, bacterial counts were inversely correlated with chorion thinning, even excluding histologic chorioamnionitis (p<0.0001 and p = 0.05). CONCLUSIONS: Fetal chorion was uniformly thinner at rupture site compared to distant sites. In PPROM fetal chorion, we demonstrated pronounced global thinning. Although cause or consequence is uncertain, bacterial presence is greatest and inversely correlated with chorion thinning among PPROM subjects.

Androgen deprivation results in time-dependent hypoxia in LNCaP prostate tumours; informed scheduling of the bioreductive drug AQ4N improves treatment response

Androgen withdrawal induces hypoxia in androgen-sensitive tissue; this is important as in the tumour microenvironment hypoxia is known to drive malignant progression. This study examined the time-dependent effect of androgen deprivation therapy (ADT) on tumour oxygenation and investigated the role of ADT-induced hypoxia on malignant progression in prostate tumours. LNCaP xenografted tumours were treated with anti-androgens and tumour oxygenation measured. Dorsal skin fold chambers (DSF) were used to image tumour vasculature in vivo. Quantitative PCR (QPCR) identified differential gene expression following treatment with bicalutamide. Bicalutamide and vehicle-only treated tumours were re-established in vitro and invasion and sensitivity to docetaxel were measured. Tumour growth delay was calculated following treatment with bicalutamide combined with the bioreductive drug AQ4N. Tumour oxygenation measurements showed a precipitate decrease following initiation of ADT. A clinically relevant dose of bicalutamide (2mg/kg/day) decreased tumour oxygenation by 45% within 24h, reaching a nadir of 0.09% oxygen (0.67±0.06 mmHg) by day 7; this persisted until day 14 when it increased up to day 28. Using DSF chambers, LNCaP tumours treated with bicalutamide showed loss of small vessels at days 7 and 14 with revascularization occurring by day 21. QPCR showed changes in gene expression consistent with the vascular changes and malignant progression. Cells from bicalutamide-treated tumours were more malignant than vehicle-treated controls. Combining bicalutamide with AQ4N (50mg/kg; single dose) caused greater tumour growth delay than bicalutamide alone. This study shows that bicalutamide-induced hypoxia selects for cells that show malignant progression; targeting hypoxic cells may provide greater clinical benefit.