变压吸附技术在焦炉煤气制氢中的应用

介绍了变压吸附 (PSA)技术的基本原理及其应用于焦炉煤气提氢的 Sysiv和 Bergbau PSA制氢典型工艺。指出PSA技术是近年国内外发展最快、技术最成熟、成本最低的煤气制氢方法 ,在国内焦炉煤气制氢中最具发展前途 ,应大力推广应用。     

PSA变压吸附制氢技术在本钢的应用

通过对本钢PSA变压吸附氢气提纯技术的介绍,分析了五塔三均变压吸附的特点,分析了本钢PSA制氢工艺的优越性。     

焦炉煤气变压吸附制氢在宝钢的应用

介绍了变压吸附制氢(PSA)工艺,分析了宝钢变压吸附制氢生产中两种运行故障,阐述了变压吸附的优越性,以及该工艺在宝钢的应用前景。     

变压吸附制氢技术在邯钢冷轧工程中的应用

介绍了变压吸附(PSA)技术在邯钢冷轧工程中应用于焦炉煤气提氢的工艺及特点。通过与水电解制氢方法进行比较,指出焦炉煤气变压吸附制氩装置具有投资少、产量大、运行费用低等优点。     

萘对PSA装置的危害及其脱除工艺

简介了PSA装置的制氢工艺,分析了萘对生产的危害性,并对脱萘工艺流程的实施效果作了介绍。     

天然气重整制氢工艺在大型粉末冶金企业的应用前景

介绍了水电解制氢和天然气重整制氢技术的原理及其工艺。通过综合比较与技术分析，天然气重整制氢工艺在生产成本上具有较大的优势，且在粉末冶金企业已有成功应用先例。在大型粉末冶金企业，该制氢工艺完全可以取代水电解制氢工艺。     

PSA氢提纯装置出口苏丹

由成都华西化工研究所为苏丹喀土穆炼油厂设计、承建的１１０００ｍ３／ｈ催化干气变压吸附ＰＳＡ氢提纯装置于２０００年５月１日一次开车成功，投入生产运行。该氢提纯装置是目前我国出口的最大的ＰＳＡ制氢装置，为国家创外汇１００多万美元。装置一次开车成功，能稳定运行，证明了成都华西化工研究所的ＰＳＡ氢提纯装置工艺设计合理，吸附技术先进，自动化程度高，并具有强的原料气适应能力。这也标志着我国的ＰＳＡ制氢技术已达到了国际先进水平，并实现了中国气体行业由进口到出口的转变。PSA氢提纯装置出口苏丹     

天然气重整制氢工艺在大型粉末冶金企业中的应用及前景分析

介绍了水电解制氢和天然气重整制氢技术的原理及其工艺流程。通过综合比较与技术分析，指出天然气重整制氢工艺在生产成本方面有较大优势，且在粉末冶金企业中已有成功应用的先例；并强调在大型粉末冶金企业中，该制氢工艺完全可以取代水电解制氢工艺。     

氢冶金还原性气体的制备研究进展

氢冶金是一种绿色低碳的冶炼工艺，是实现钢铁行业转型升级和改变高碳排放形象的有效途径。氢冶金是通过纯氢气或富氢气体替代传统焦炭直接还原铁，可实现CO₂减排。富氢还原性气体的制备是实现氢冶金的关键之一。对比分析了适合于氢冶金的规模化焦炉煤气制氢、天然气制氢、煤制氢和氨分解制氢技术的工艺及相关催化剂，探讨了包括电解水制氢在内的可再生能源制氢的途径。氢冶金技术需要的制氢技术日趋成熟，氢冶金也将成为未来钢铁行业升级改造的重点。     

天然气制氢技术及其在合金工业中的应用

介绍天然气制氢工艺原理及过程,结合合金工业对氢气品质的要求,从理论和相关行业的应用实例阐述天然气制氢替代传统水电解制氢的可行性,从经济效益和社会效益两方面说明有必要大力推广天然气制氢技术在合金工业中的应用。     

Public laboratories for vaccine production: a new paradigm

The development of increasingly specific diagnostic assays has allowed the detection of various forms of prostate-specific antigen (PSA). It has been found that the proportion of free to total PSA (percent free PSA) is significantly lower in men with prostate cancer than in those with other benign diseases. In order to distinguish early, curable prostate cancer from benign prostatic hyperplasia (BPH), percent free PSA measurement is most useful when the total PSA value is 3-10 ng/ml. The measurement of the proportions of these different forms of PSA, i.e., percent free PSA, may constitute an important diagnostic tool, able to differentiate between benign and malignant prostatic disease with increased specificity, reducing false-positive results and, therefore, improve patient prognosis.     

Individual prostate-specific antigen (PSA) forms as prostate tumor markers

Prostate-specific antigen (PSA) is a kallikrein-like serine protease mainly expressed in the human prostate. It is responsible for the proteolysis of the gel-forming proteins in human semen. Two major extracellular protease inhibitors, alpha-1-antichymotrypsin (ACT) and alpha-2-macroglobulin (AMG) may inactivate PSA escaping from the prostate. The predominant immunodetected form of PSA in serum is complexed to ACT but PSA exists also in a free non-complexed form despite the large excess of inhibitors. The concentrations of PSA in serum are normally less than 4 micrograms/l. but elevated concentrations are found in a majority of patients with prostate cancer (CAP) and the analysis of PSA in serum has become invaluable in the detection and monitoring of patients with CAP. However, it is not an ideal tumor marker in the sense that there are CAP patients with normal PSA concentrations in serum and patients with benign hyperplasia of the prostate (BPH) with elevated PSA concentrations. Analysis of the various PSA forms in serum attracts much interest as there is a higher proportion of PSA in complex with ACT in patients with CAP than in those with BPH. Optimal combinations of monoclonal antibodies have been used to design sensitive noncross-reacting immunoassays for the detection of free PSA, PSA-ACT complexes and the detection of both free PSA and PSA complexes in an equimolar fashion (i.e. total PSA). Several studies have demonstrated that the analysis of the proportions of the free-to-total PSA in serum may increase the diagnostic specificity by 15-20% without significant loss in the sensitivity for detection of CAP.     

Errors in measurement of acetabular index

The usefulness of the fPSA fraction in the differential diagnosis of benign prostate hyperplasia (BPH) and prostate cancer was evaluated, with the aim of improving the diagnostic efficacy of PSA. Serum PSA and fPSA determinations were performed by an enzymoimmunoassay technique on an ES-300 system. fPSA constitutes a minor fraction both in normal subjects and in patients with prostate disease, being significantly lower in patients with untreated prostate cancer than in patients with BPH. Likewise, the authors have observed that the sensitivity of the fPSA/PSA ratio has an inversely proportional relationship with the stage of the disease. The results obtained in patients with PSA levels between 4 and 20 micrograms/l are also of note. In this series of patients, the efficacy of the fPSA/PSA ratio was higher than that of PSA, showing a sensitivity of 44% and a specificity of 95% at the cut-off of 0.08.     

Isolation and characterization of free form prostate specific antigen (f-PSA) in sera of men with prostate cancer

PURPOSE: The free uncomplexed form of prostate specific antigen (f-PSA) from prostate cancer sera was partially isolated and characterized because the molecular form of f-PSA in the serum is unknown. MATERIALS AND METHODS: 230 ml. of sera from 59 men with bone metastasis and individual PSA values of >2000 ng./mL were combined and centrifuged for 60 minutes at 30,000 RPM (4C). The sera were fractionated by gel filtration column chromatography (Sephacryl S-200, 2.5 cm. x 92 cm.). Free and complexed PSA in the eluted fractions were isolated by measuring immunoreactivity of PSA (Tosoh AIA-600 assay); f-PSA from 23 separate runs were combined, concentrated and re-chromatographed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to immobilize the isolated proteins onto a nitrocellulose membrane and a polyvinylidene difluoride (PVDF) membrane. Monoclonal antibody (F5) was used to probe PSA on nitrocellulose membrane and the PSA band was detected by Emission Chemoluminescence (ECL) kit. Amino terminal sequence analysis of the isolated f-PSA was performed with a gas-phase sequentor (Applied Biosyntens 4760 A) using the program designed by the manufacturer. RESULTS: 0.5 cc of f-PSA (27,000 ng./mL) was obtained from serums after rechromatography. SDS-PAGE showed one double band around 30 kDa; with ECL technique, one major band at 30-kDa was identified as PSA. The amino terminal sequence analysis of this band showed residue 1 through 9 and 146 through 152. CONCLUSIONS: In our preliminary experiment, the free form of serum PSA is partially isolated directly from human sera. Amino terminal sequence analysis has shown that serum f-PSA is not a pre-mature or zymogen form of PSA because serum f-PSA has a N-terminus identical to that of seminal fluid PSA. A nicked form of f-PSA is also found in these patient sera.     

Does mandating continuing education mandate competence?

Serial prostate-specific antigen (PSA) measurements (PSA velocity) as an additional instrument to detect prostatic cancer was introduced in 1992. It has previously been reported that PSA increase per year differed in the last 5 years prior to diagnosis in patients with benign prostatic hyperplasia (0.18 ng/ml/year), locally confined (0.75 ng/ml/year) and metastasized (4.4 ng/ml/year) cancer of the prostate (CaP) in contrast to healthy men (0.04 ng/ml/year). The ability of PSA velocity to detect organ-confined CaP in patients with intermediate PSA serum values depends therefore on a reliable and reproducible PSA result. The present study comprised 85 men with PSA values between 3 and 8 ng/ml (Abbott IMx). PSA measurements were repeated with Abbott IMx (n = 85 patients) and Hybritech Tandem-E (n = 59 patients) assays. The PSA serum values differed from one examination to the other from 0.02 to 2.74 ng/ml with the Abbott IMx. Standard deviation amounted to 0.35 ng/ml with the Abbott IMx PSA assay. Using the Hybritech Tandem-E assay, mean standard deviation was 1.15 ng/ml and therefore higher than with the Abbott IMx assay. The difference from one test to the other ranged from 0.05 to 4.05 ng/ml with the Hybritech Tandem-E. Using the Abbott IMx assay, 10.6% of all repeat measurements exceeded 1 ng/ml whereas in the Hybritech Tandem-E assay 62.7% of the second measurements differed > 1 ng/ml from the first PSA result. An increase in PSA serum values may therefore be due to intratest variation, physiological day-to-day variation as well as prostatic disease. It is important to notice that the intra-assay variation may be greater than the PSA increase per year in a patient with CaP. Therefore, PSA velocity seems to be of limited value.     

Newer applications of serum prostate-specific antigen in the management of prostate cancer

The information contained in this article indicates that PSA will have an increasing role in the management of prostate cancer. For example, it is now essential for optimal diagnosis if prostate cancer detection is the goal. Prospects are high that more information about PSA density relationships, PSA velocity phenomenologies, and possible PSA isoforms will increase diagnostic accuracy. It would also seem that PSA will improve staging accuracy not only by better manipulation of multiple preoperative parameters (eg, cancer grade, volume, PSA, etc) but possibly by the molecular detection of minute amounts of occult prostate cancer cells in bone, blood or lymph nodes, or by improved use of immune scanning. Finally, the use of these more sophisticated staging approaches together with increasingly sensitive PSA assays and possibly androgen provocative testing might allow the prospect that the potentially curative therapies can be almost immediately assessed for efficacy, thereby increasing prospects for therapeutic progress. Finally, PSA may become even more important for manipulating hormone therapies (eg, IAS therapy) or it could form a basis for new treatments such as immune or gene therapy.     

Extraprostatic production of prostate specific antigen is under hormonal control

PURPOSE: Prostate specific antigen (PSA) is the most useful tumor marker in urology. It is produced primarily by the epithelial cells of the ducts and acini of the prostate gland. Extraprostatic production of PSA is provided mainly by the periurethral glands, leading to measurable urine but undetectable serum levels of PSA in women and in men following radical prostatectomy for pathologically localized disease. MATERIALS AND METHODS: We investigated the effect of continuous testosterone substitution (250 mg. every 4 weeks) on urinary PSA excretion in 20 patients who converted from the female to male gender. We compared the results to urine levels in 20 women who did not receive testosterone. RESULTS: Mean urinary PSA plus or minus standard deviation was 1.73 +/- 1.68 ng./ml. in controls and 12.03 +/- 10.47 ng./ml. in converted patients, a statistically significant difference (p < 0.0001). Serum PSA did not differ between groups. CONCLUSIONS: Our data demonstrate that extraprostatic PSA production is under androgen control.     

Prostate-specific antigen in the follow-up of conservatively treated prostatic cancer

The determination of serum prostate specific antigen (PSA) has made the diagnosis of prostate cancer easier. PSA is also used extensively in the follow-up of patients, both treated and untreated. On the basis of material from 308 patients who were mainly managed conservatively, we discuss the usefulness of this practice. It is important to monitor PSA after radical treatment because an increase may indicate local recurrence. In some patients this may lead to further treatment with cure as the aim. For patients under observation only, or those being treated by endocrine intervention, the value of regular PSA measurements is less certain. Where such patients were followed up for at least three years, we found considerable overlaping of PSA values among patients with different outlooks. Within the present therapeutic possibilities it may be better to base their management on clinical signs rather than on PSA. Regular measurements of PSA lead to focusing on this variable, causing unnecessary distress to patients months, or even years, before clinical progression of the disease.     

The PSA gene: value in detection of circulating prostate cancer cells

There has been a renewed interest in detection of circulating cancer cells due to the simplicity, specificity and sensitivity of a molecular biology technique: RT-PCR. This detection is based on the concept of specificity of an RNA sequence expressed by a cancer cell. PSA appears to be the ideal marker for circulating prostate cancer cells due to its specificity. The authors review the genes of the kallikrein family and discuss the advantages and difficulties involved in the use of PSA messenger RNA as a marker for circulating prostate cancer cells.