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Search Results: 1 - 10 of 43970 matches for " Nanqi Wu "
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Effect of Natural Fiber Reinforced Polypropylene Composite Using Resin Impregnation  [PDF]
Gibeop Nam, Nanqi Wu, Kazuya Okubo, Toru Fujii
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.513143
Abstract:
In this paper, we deals with mechanical performance of resin impregnation with natural fiber and fiber reinforced composites. The effect of the addition of a rein impregnation process on static strength of the injection molded composites was investigated by carrying out tensile and banding tests, followed by Scanning electron microscopy (SEM) observation of fiber surface and fracture surface of composites. The tensile strength of natural fiber and natural fiber reinforced composites with resin impregnation method increases with Polyvinyl alcohol (PVA) impregnation. In addition, Phenol resin impregnation recovers fiber tensile strength after alkali treatment. Resin impregnation causes decrease in contact surface area; however, it does not cause decrease in mechanical properties. Our results suggest that the using rein impregnation method has better effect on the mechanical properties of natural fiber reinforced Polypropylene (PP) composites.
Biodegradation of phenol and m-cresol by mutated Candida tropicalis

Yan Jiang,Xun Cai,Di Wu,Nanqi Ren,

环境科学学报(英文版) , 2010,
Abstract: The phenol and m-cresol biodegradations were studied using the mutant strain CTM 2 obtained by the He-Ne laser irradiation on wild-type Candida tropicalis. The results showed that C. tropicalis exhibited the increased capacity of phenolic compounds degradation after laser irradiation. It could degrade 2600 mg/L phenol and 300 mg/L m-cresol by 5% inoculum concentration, respectively. In the dual-substrate biodegradation system, 0-500 mg/L phenol could accelerate m-cresol biodegradation, and 300 mg/L m-cresol could be completely utilized within 46 hr at the presence of 350 mg/L phenol. Besides, the maximum biodegradation of m-cresol could reach 350 mg/L with 80 mg/L phenol within 61 hr. Obviously, phenol, as a growth substrate, could promote CTM 2 to degrade m-cresol, and was always preferentially utilized as carbon source. Comparatively, low-concentration m-cresol could result in a great inhibition on phenol degradation. In addition, the kinetic behaviors of cell growth and substrate biodegradation were described by kinetic model proposed in our laboratory.
Microbial community structure in an integrated A/O reactor treating diluted livestock wastewater during start-up period

Lijiao Ren,Yining Wu,Nanqi Ren,Kun Zhang,Defeng Xing,

环境科学学报(英文版) , 2010,
Abstract: In order to investigate the correlation between reactor performance and the microorganisms, an integrated A/O reactor was operated for 72 days to treat diluted livestock wastewater. Chemical oxygen demand (COD) removal e ciency increased from 79% to 94%, with total nitrogen (TN) removal e ciency from 37% to 50% (HRT 7.4 hr) when the influent COD and TN were ca. 1500 mg/L and 95 mg/L, respectively, and the outlet COD concentration was less than 100 mg/L at the end. Microbial community was monitored during start-up period by denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA gene. DGGE profiles showed that microbial community had changed significantly during the start-up and these shifts were in accordance with the reactor performance. UPGMA clustering analysis showed that 14 anaerobic samples fell into five main groups and so did the aerobic ones, but the grouping patterns were di erent. Phylogenetic analysis indicated that microbial populations in the anaerobic compartment belonged to Firmicutes, Proteobacteria, Chloroflexi and Bacteroidetes, while Proteobacteria, Bacteroidetes, Firmicutes, Verrucomicrobiae and Nitrospira were present in the aerobic compartment. In the anaerobic compartment, more fermentative and acetogenic bacteria were detected during the start-up while denitrifying bacteria faded away. Two functional populations such as Nitrospira defluvii and Dechloromonas denitrificans were observed when nitrogen removal was high, indicating that simultaneous nitrification and denitrification occurred in the aerobic compartment.
Properties and coagulation mechanisms of polyferric silicate sulfate with high concentration
SONG Zhiwei,REN Nanqi,
SONG Zhiwei
,REN Nanqi

环境科学学报(英文版) , 2008,
Abstract: Polyferric silicate sulfate (PFSS) with high concentration was prepared using the composite-poly method. The coagulation properties and mechanisms of this new complex were probed using TEM, Fe-Ferron timed complex-colorimetric method, and infrared spectrum method. The results showed that the flocculating effect of polyferric silicate sulfate had an advantage over polyferric sulfate (PFS), as the optimum coagulation effect could be obtained when the Si/Fe mole ratio was 0.75 in accordance with its macrostructure of PFSS.According to the Fe-Ferron timed complex-colorimetric method, the Si species was mainly Sic, whereas, the Fe species were Fea and Fec in the copolymerization system. The infrared spectra indicated that the structure of these new flocculants was formed by polymers,mainly by olation, which was different from polyferric sulfate, and the vibration of M-OH-M of around 1100 cm-1, also proved that there existed Fe-OH-Fe and its polymers in some forms.
Monitoring of microbial community structure and succession in the biohydrogen production reactor by denaturing gradient gel electrophoresis (DGGE)
Defeng Xing,Nanqi Ren,Manli Gong,Jianzheng Li,Qiubo Li
Science China Life Sciences , 2005, DOI: 10.1007/BF02879668
Abstract: To study the structure of microbial communities in the biological hydrogen production reactor and determine the ecological function of hydrogen producing bacteria, anaerobic sludge was obtained from the continuous stirred tank reactor (CSTR) in different periods of time, and the diversity and dynamics of microbial communities were investigated by denaturing gradient gel electrophoresis (DGGE). The results of DGGE demonstrated that an obvious shift of microbial population happened from the beginning of star-up to the 28th day, and the ethanol type fermentation was established. After 28 days the structure of microbial community became stable, and the climax community was formed. Comparative analysis of 16S rDNA sequences from reamplifying and sequencing the prominent bands indicated that the dominant population belonged to low G+C Gram-positive bacteria (Clostridium sp. andEthanologenbacterium sp.), β-proteobacteria (Acidovorax sp.), γ-proteobacteria (Kluyvera sp.), Bacteroides (uncultured bacterium SJA-168), and Spirochaetes (uncultured eubacterium E1-K13), respectively. The hydrogen production rate increased obviously with the increase ofEthanologenbacterium sp.,Clostridium sp. and uncultured Spirochaetes after 21 days, meanwhile the succession of ethanol type fermentation was formed. Throughout the succession the microbial diversity increased however it decreased after 21 days. Some types ofClostridium sp.Acidovorax sp.,Kluyvera sp., and Bacteroides were dominant populations during all periods of time. These special populations were essential for the construction of climax community. Hydrogen production efficiency was dependent on both hydrogen producing bacteria and other populations. It implied that the cometabolism of microbial community played a great role of biohydrogen production in the reactors.
Preparation and characterization of a lipoid adsorption material and its atrazine removal performance

Zhiqiang Chen,Qinxue Wen,Jiaxiang Lian,Nanqi Ren,

环境科学学报(英文版) , 2011,
Abstract: A novel adsorbent named lipoid adsorption material (LAM),with a hydrophobic nucleolus (triolein) and a hydrophilic membrane structure (polyamide),was synthesized to remove hydrophobic organic chemicals (HOCs) from solution.Triolein,a type of lipoid,was entrapped by the polyamide membrane through an interfacial polymerization reaction.The method of preparation and the structure of the LAM were investigated and subsequent experiments were conducted to determine the characteristics of atrazine (a type of HOC) removal from wastewater using LAM as the adsorbent.The results showed that LAM had a regular structure compared with the prepolymer,where compact particles were linked with each other and openings were present in the structure of the LAM in which the fat drops formed from triolein were entrapped.In contrast to the atrazine adsorption behavior of powdered activated carbon (PAC),LAM showed a persistent adsorption capacity for atrazine when initial concentrations of 0.57,1.12,8.31 and 19.01 mg/L were present,and the equilibrium time was 12 hr.Using an 8 mg/L initial concentration of atrazine as an indicator of HOCs in aqueous solution,experiments on the adsorption capacity of the LAM showed 69.3% removal within 6-12 hr contact time,which was close to the 75.5%removal of atrazine by PAC.Results indicated that LAM has two atrazine removal mechanisms,namely the bioaccumulation of atrazine by the nucleous material and physical adsorption to the LAM membrane.Bioaccumulation was the main removal mechanism.
Influence of temperature on the characteristics of aerobic granulation in sequencing batch airlift reactors

SONG Zhiwei,REN Nanqi,ZHANG Kun,TONG Longyan,

环境科学学报(英文版) , 2009,
Abstract: Aerobic granular sludge were cultivated in sequencing batch airlift reactors (SBAR) at 25, 30 and 35℃,respectively. The effects of temperature on the granules characteristics were analyzed and the microbial community structures of the granules were probed using scanning electron micrograph (SEM) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that 30℃ is optimum for matured granules cultivated, where the granules had more compact structure, better settling ability and higher bioactivity, the OUR reached to 1.14 mg O2/(g MLVSS·min) with 97% removal rate of COD and 75% removal rate of TP, and the removal efficiency of NH3-N increased along with the temperature rising in the range of 68.5%-87.5%. DGGE profiles revealed that microbial community structure at 25℃ showed the lowest similarity with others, the sequencing results indicated that most of dominant microbes belonged to Actinobacteria and Proteobacterium. Thermomonas sp., Ottowia sp. and Curtobacterium ammoniigenes may act important roles respectively at different temperature.
Bulking sludge for PHA production:Energy saving and comparative storage capacity with well-settled sludge
Qinxue Wen,Zhiqiang Chen,Changyong Wang,Nanqi Ren,
Qinxue Wen
,Zhiqiang Chen,Changyong Wang,Nanqi Ren

环境科学学报(英文版) , 2012,
Abstract: Two acetate-fed sequencing batch reactors (SBR) were operated under an aerobic dynamic feeding (ADF) model (SBR #2) and with anaerobic phase before aerobic phase (SBR #1) to select mixed cultures with a high polyhydroxyalkanoates (PHA) storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability (SBR #1), however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB (polyhydroxybutyrate) cell content and ΔPHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ac/(Cmol X.hr) and 0.18 Cmol Ac/(Cmol PHB.hr), respectively, resulting a yield of 0.45 Cmol PHB/(Cmol Ac) in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/(Cmol PHB.hr) was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge. Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.
Effects of various pretreatment methods on mixed microflora to enhance biohydrogen production from corn stover hydrolysate
Effects of pretreatment methods on fermentative hydrogen production from corn stover hydrolysate

Kun Zhang,Nanqi Ren,Changhong Guo,Aijie Wang,Guangli Cao,
Kun Zhang
,Nanqi Ren,Changhong Guo,Aijie Wang,Guangli Cao

环境科学学报(英文版) , 2011,
Abstract: Five individual pretreatment methods, including three traditional widely-used protocols (heat, acid and base) and two novel attempts (ultrasonic and ultraviolet), were conducted in batch tests to compare their effects on mixed microflora to enhance hydrogen (H2) production from corn stover hydrolysate. Experimental results indicated that heat and base pretreatments significantly increased H2 yield with the values of 5.03 and 4.45 mmol H2/g sugar utilized respectively, followed by acid pretreatment of 3.21 mmol H2/g sugar utilized. However, compared with the control (2.70 mmol H2/g sugar utilized), ultrasonic and ultraviolet pretreatments caused indistinctive effects on H2 production with the values of 2.92 and 2.87 mmol H2/g sugar utilized respectively. The changes of soluble metabolites composition caused by pretreatment were in accordance with H2-producing behavior. Concretely, more acetate accumulation and less ethanol production were found in pretreated processes, meaning that more NADH might be saved and flowed into H2-producing pathways. PCR-DGGE analysis indicated that the pretreatment led to the enrichment of some species, which appeared in large amounts and even dominated the microbial community. Most of the dominated species were affiliated to Enterobacter spp. and Escherichia spp. As another efficient H2 producer, Clostridium bifermentan was only found in a large quantity after heat pretreatment. This strain might be mainly responsible for better performance of H2 production in this case.
Statistical Optimization of Operational Parameters for Enhanced Naphthalene Degradation by Photocatalyst
Aijuan Zhou,Jing Peng,Zhaobo Chen,Jingwen Du,Zechong Guo,Nanqi Ren,Aijie Wang
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/607283
Abstract: The optimization of operational parameters for enhanced naphthalene degradation by TiO2/Fe3O4-SiO2 (TFS) photocatalyst was conducted using statistical experimental design and analysis. Central composite design method of response surface methodology (RSM) was adopted to investigate the optimum value of the selected factors for achieving maximum naphthalene degradation. Experimental results showed that irradiation time, pH, and TFS photocatalyst loading had significant influence on naphthalene degradation and the maximum degradation rate of 97.39% was predicted when the operational parameters were irradiation time 97.1 min, pH 2.1, and catalyst loading 0.962 g/L, respectively. The results were further verified by repeated experiments under optimal conditions. The excellent correlation between predicted and measured values further confirmed the validity and practicability of this statistical optimum strategy.
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