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Biomedical subjects

H Q Yu

Publications and source records attributed to H Q Yu.

At least 19 recordsLinked to original sources
PubMed2005

Influence of NaCl on hydrogen production from glucose by anaerobic cultures.

In this study, batch experiments were conducted to investigate the inhibitory effects of NaCl on H2 production from glucose by anaerobic mixed cultures. Experimental results demonstrate that NaCl concentration had significant inhibitory effects on glucose degradation, cumulative H2 production, specific H2 production rate, H2 yield and the distribution of aqueous products. The specific H2 production rate had a negative correlation with NaCl concentrations. The NaCl concentrations, at which the specific H2 production rate and H2 yield were reduced by 50%, were estimated as 209 mM and 443 mM, respectively.

Bacteria, Anaerobic↗
PubMed2003

Treatment of coke-plant wastewater by biofilm systems for removal of organic compounds and nitrogen.

Coke-plant wastewater was treated by an anaerobic-anoxic-aerobic (A(1)-A(2)-O) biofilm system and an anoxic-aerobic (A/O) biofilm system, respectively. At same or similar levels of hydraulic retention time (HRT), the two systems had almost identical chemical oxygen demand (COD) and NH(3) removals, but a different organic-N removal. Set-up of an acidogenic stage benefited for the removal of organic-N and the A(1)-A(2)-O system was more useful for total nitrogen removal than the A-O system. HRT did not have a substantial effect on the COD and NH(3)-N removal efficiencies, but considerably influenced the organic-N removal and distribution of oxidized nitrogen in the final effluent. The GC/MS analysis demonstrated that some refractory compounds were decomposed at the acidogenic stage and resulted in the production of some intermediates, which were more readily degraded in the subsequent aerobic stage. Hence, the A(1)-A(2)-O system had better effluent quality than the A-O system in terms of effluent composition.

Bacteria, Aerobic↗
PubMed2003

High-rate anaerobic hydrolysis and acidogenesis of sewage sludge in a modified upflow reactor.

Continuous experiments were conducted to study the hydrolysis and acidogenesis of sewage sludge in an upflow reactor with an agitator and a gas-liquid-solid separator. Results of this study showed that 34-78% of volatile suspended solids (VSS) in sewage sludge was hydrolyzed at pH in the range 4.0-6.5, 35 degrees C and 4-24 hours of hydraulic retention time (HRT). About 31-65% of carbohydrate in sewage sludge, 20-45% of protein and 14-24% of lipid were acidified in this reactor. Hydrogen production was favored in lower pH and HRT, whereas methane production was encouraged at higher pH and HRT. Acetate, propionate, butyrate, and i-butyrate were the main aqueous acidogenic products. The distribution of these compounds in the effluent was more sensitive to pH, but was less sensitive to HRT. The maximu specific COD solubilization rate and specific volatile fatty acids production rate were 126 mg-COD/g-VSS x d and 102 mg-VFAIg-VSS x d, respectively. Compared with a CSTR, this modified upflow reactor was shown to be a more promising biosystem for the hydrolysis and acidogenesis of sewage sludge.

Bacteria, Anaerobic↗
PubMed2002

Anaerobic acidification of a synthetic wastewater in batch reactors at 55 degrees C.

Experiments were conducted to study the acidogenesis of a dairy wastewater in batch reactors at pH 5.5 and 55 degrees C. There was a biased fermentation sequence for carbohydrate and protein, and the protein fermentation was delayed by carbohydrate. The production of hydrogen was exclusively from the fermentation of carbohydrate. Acetate and butyrate concentrations both increased rapidly at the beginning and peaked at some points, then declined in the reactors fed with 8 g-COD (chemical oxygen demand)/l, or higher concentrations. Butanol and propanol fractions increased with the substrate concentration. The metabolism shifted from the volatile fatty acid-producing pathways to the alcohol-producing pathways when the substrate concentration increased beyond 8 g-COD/l. The acidogenic biomass yield was in the range 0.19-0.25 mg-VSS/mg-COD.

Agriculture↗
PubMed2001

The roles of calcium in sludge granulation during UASB reactor start-up.

Six upflow anaerobic sludge blanket (UASB) reactors were concurrently operated for 146 d to examine the effects of calcium on the sludge granulation process during start-up. Introduction of Ca2+ at concentrations from 150 to 300 mg/l enhanced the biomass accumulation and granulation process. The calcium concentration in the granules was nearly proportional to the calcium concentration in the feed, and calcium carbonate was the main calcium precipitate in the granules. The specific activity of granules decreased with increasing influent calcium concentration. The optimum calcium concentration for the granulation was from 150 to 300 mg/l. The addition of low-concentration calcium to the UASB reactors appeared to enhance the three steps of sludge granulation: adsorption, adhesion and multiplication, but it did not lead to a different proliferation of predominant microorganisms in the granules.

Anaerobiosis↗
PubMed2001

Acidification of mid- and high-strength dairy wastewaters.

Batch and continuous experiments were conducted to study the influence of dairy wastewater strength (2-30g-COD/L) on acidification at pH 5.5 and 37 degrees C. Results of batch experiments showed that carbohydrate was preferentially acidified as compared to protein and lipid. Production of VFAs (mainly acetate, propionate and butyrate) and hydrogen corresponded to carbohydrate acidification, whereas production of alcohols (mainly ethanol, propanol and butanol), plus i-butyrate and higher molecular-weight VFAs, corresponded to protein acidification. In treating high-strength wastewaters (8-30 g-COD/ L), acetate, butyrate and P(H2) decreased after reaching their peak levels before leveling off. Results of continuous experiments with 12h of hydraulic retention showed that acidification decreased with the increase of wastewater COD, from 57.1% at 2 g-COD/L to 28.8% at 30 g-COD/L; among the constituents in dairy wastewater, 92-99% of carbohydrates, 59-85% of protein and 12-42% of lipid were acidified. High-strength wastewater favored production of hydrogen and alcohols, especially propanol and butanol. The biomass yield was 0.258g-VSS/g-COD.

Agriculture↗
PubMed2001

Enhanced sludge granulation in upflow anaerobic sludge blanket (UASB) reactors by aluminum chloride.

Two upflow anaerobic sludge blanket (UASB) reactors were concurrently operated for 146 days to examine the effects of aluminum chloride (AlCl3) on the sludge granulation process during start-up. Sludge granulation (defined as that over 10% of granules were larger than 2.0 mm) was achieved in the control reactor (R1) in approximate three months. Introduction of Al3+ at a concentration of 300 mg/l reduced the sludge granulation time by approximate one month. Throughout the experiment the AlCl3-added reactor (R2) had a higher biomass concentration, e.g., 13.8 g-MLVSS/l versus 12.8 g-MLVSS/l on Day 146. Granules became visible earlier in R2 compared with R1 (35 days versus 65 days). The average size of granules from R2 was larger than that from R1. The results demonstrated that AlCl3 enhanced the sludge granulation process in the UASB reactors.

Aluminum Chloride↗
PubMed2001

Inhibition on acidogenesis of dairy wastewater by zinc and copper.

Acidogenesis of dairy wastewater produced volatile fatty acids, mainly acetate and propionate, plus hydrogen as by-product. Zinc (Zn) inhibited acidogenesis at concentrations over 10 mg l(-1); but at 10 mg l(-1), or less, it enhanced acidogenesis slightly. On the other hand, copper (Cu) inhibited acidogenesis at all tested concentrations ranging 5-400 mg l(-1). Production of acetate was inhibited by both metals at all concentrations; but production of propionate and hydrogen was favored at low concentrations of Zn (up to 80 mg l(-1)) and Cu (up to 40 mg l(-1)). Production of hydrogen corresponded with the degradation of carbohydrate and the production of propionate. Overall, Cu was 1.4-4.3 folds more toxic than Zn, according to the overall production patterns of fatty acids and hydrogen as well as degradation patterns of carbohydrate and protein.

Carbohydrates↗
PubMed2001

Inhibition by chromium and cadmium of anaerobic acidogenesis.

The effects of chromium (III) and cadmium on the anaerobic acidogenesis of a simulated dairy waste were examined using serum vials. At Cd dosages less than 20 mg/l, the acidogenesis process was enhanced by the dosage, resulting in a higher degree of acidification, protein conversion, and hydrogen production than the control. At dosages over 20-mg/l, Cd inhibited the acidogenesis. The Cr (III) dosage of 5 mg/l reduced overall volatile fatty acid and alcohol generation, degree of acidification, conversions of lactose, lipid and protein, and total biogas production, with the exception of accumulation of hydrogen and propionate. At dosages exceeding 5 mg/l, Cr (III) had a severe inhibition on the acidogenesis. The Cd concentrations which caused a 50% reduction in total volatile fatty acid and alcohol production, degree of acidification and cumulative gas production were higher than the corresponding values caused by Cr (III), suggesting that Cr (III) was more toxic to acidogenic bacteria than Cd.

Alcohols↗
PubMed2000

Thermophilic acidification of dairy wastewater.

Acidification of simulated dairy wastewater was conducted in an upflow reactor at 55 degrees C. Results showed that the degree of acidification decreased with the increase in chemical oxygen demand (COD) loading rate, from 60.8% at 4 g l(-1) day(-1) to 27.1% at 24 g l(-1) day(-1). Carbohydrate was readily degraded at all loading rates, but degradation of protein and lipid decreased with the increase in loading rate. Most carbohydrate degradation occurred at the reactor bottom, whereas protein was degraded mainly after the carbohydrate became depleted. The predominant acidification products were acetate, propionate, butyrate and ethanol, whereas formate, i-butyrate, valerate, i-valerate, caproate, lactate, methanol, propanol and butanol were present in lesser quantities. The increase in loading rate resulted in the increase of propionate and the decrease of acetate, but had little effect on ethanol and butyrate productions. Only 2.5-8.8% of influent COD was converted to hydrogen and methane. The biomass yield was 0.30-0.43 mg VSS mg(-1) COD.

Alcohols↗
PubMed1994

[Analysis of the influence factors on the resection and prognosis of thymic tumors].

One hundred eleven thymic tumors were intervened surgically, including 92 thymoma, 8 thymic carcinoid, and 10 thymic carcinoma. In this series 50.9% of the cases were complicated with various syndrome, 44.5% with myasthenia gravis (MG), more frequently in the epithelial cell type. Pure red cell aplasia often associated with the spindle-cell thymoma. Of the thymic carcinoid 50% had ectopic ACTH syndrome. Resection rate correlated with the size and invasion of the tumor. There were significant difference in resection rate among thymoma, thymic carcinoid, and thymic carcinoma. The degree of invasion undoubtedly influenced on resection. The 3-, 5-, and 10-year survival rates of the thymoma were 82.7%, 68.1% and 40.0% respectively. The prognosis depended on the pathological classification and the severity of neighbouring invasion, but MG had no significant effect on prognosis. Recurrence and metastasis of the tumor remained to be the main cause of late death.

Adult↗
PubMed1993

Rearrangements of the retinoic acid receptor alpha and promyelocytic leukemia zinc finger genes resulting from t(11;17)(q23;q21) in a patient with acute promyelocytic leukemia.

Cytogenetic study of a patient with acute promyelocytic leukemia (APL) showed an unusual karyotype 46,xy,t(11;17) (q23;21) without apparent rearrangement of chromosome 15. Molecular studies showed rearrangements of the retinoic acid receptor alpha (RAR alpha) gene but no rearrangement of the promyelocytic leukemia gene consistent with the cytogenetic data. Similar to t(15;17) APL, all-trans retinoic acid treatment in this patient produced an early leukocytosis which was followed by a myeloid maturation, but the patient died too early to achieve remission. Further molecular analysis of this patient showed a rearrangement between the RAR alpha gene and a newly discovered zinc finger gene named PLZF (promyelocytic leukemia zinc finger). The fusion PLZF-RAR alpha gene found in this case, was not found in DNA obtained from the bone marrow of normals, APL with t(15;17) and in one patient with AML-M2 with a t(11;17). Fluorescence in situ hybridization using a PLZF specific probe localized the PLZF gene to chromosomal band 11q23.1. Partial exon/intron structure of the PLZF gene flanking the break point on chromosome 11 was also established and the breakpoint within the RAR alpha gene was mapped approximately 2 kb downstream of the exon encoding the 5' untranslated region and the unique A2 domain of the RAR alpha 2 isoform.

Aged↗
PubMed1992

Beyond cold cardioplegia.

One hundred fifteen consecutive patients were operated on for myocardial revascularization or valvular disease or both with continuous antegrade and retrograde aerobic warm (37 degrees C) blood cardioplegia. Mean cross-clamp time was 56.3 +/- 21 minutes (+/- standard deviation). Mean reperfusion time was 18.4 +/- 11.8 minutes (range, 5 to 81 minutes). Five patients (4.3%) died, and 15 (13%) needed inotropic support. Two (1.7%) required intraaortic balloon support. Two patients (1.7%) had evidence of perioperative myocardial infarction, and 98 (85%) returned spontaneously to normal sinus rhythm. Sixteen patients had a cross-clamp time greater than 80 minutes. All 16 of them had an uneventful postoperative course except for 1 patient who required inotropic drugs. This method of myocardial protection is now used for all open heart procedures in our institution.

Adult↗
PubMed1992

[Heart surgery in normothermia and aerobiosis: apropos of 530 patients].

Between February and October 1991, 530 consecutive patients underwent myocardial revascularization or valvular surgery with warm continuous antegrade and retrograde cardioplegia (37 degrees C). Three hundred and thirty three patients had isolated myocardial revascularization, 159 valvular surgery alone and 25 had combined valvular and coronary bypass. The global mortality was 5.1%, 3.7% for coronary bypass, 7.5% for valvular surgery and 8% for combined valvular and coronary surgery. A multivariate analysis identified the "reperfusion time" as the only predictive factor of hospital mortality (p < 0.001). Intraortic balloon counterpulsation was required postoperatively in 3.2% of cases, 5.2% of coronary bypass and 0.8% of the valvular patients. Inotropic drugs were used to come off cardiopulmonary bypass in 16.5% of coronary and 37.5% of valvular patients. There were 0.9% perioperative infarctions: 1.2% in the coronary bypass cases and 0.6% in the valvular cases. Spontaneous return to sinus rythm was observed in 87.9% of cases. The average "reperfusion time" was 20.48 +/- 0.7 mn. Analysis of the influence of aortic cross clamp time on cardiac morbidity in two groups of coronary patients (Group I: short cross clamp time less than 60 mn; Group II: long cross clamp time, 60 to 33 mn) showed that the hospital mortality, the prevalence of the use of inotropic drugs and balloon counterpulsation the postoperative cardiac index, the rate of spontaneous de fibrillation and the reperfusion time did not depend on the aortic cross clamp time. Cardiac morbidity.

Adolescent↗