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Peng Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparation and thermal characterization of paraffin metal foam composite phase change material
Applied Energy, 2013Co-Authors: X Xiao, Peng Zhang, Ming LiAbstract:The utilization of paraffin in the latent thermal energy storage (LTES) system for solar energy storage is hampered by its low thermal conductivity. Paraffin/nickel foam and paraffin/copper foam composite phase change materials (PCMs) were prepared using a vacuum Impregnation method in the present study. The Impregnation ratios which reflect the actual mass fraction of pure paraffin impregnated were studied comparatively for the Impregnations with and without vacuum assistance. The surface porosity was obtained by employing the image processing approach. The thermal conductivities of the composite PCMs were measured by the transient plane heat source technique (TPS) as well as the steady state method, and the thermal behaviors were analyzed with a differential scanning calorimeter (DSC). It is found that the surface porosity obtained from image analysis was in the range of 90–94%, whereas the bulk porosity predicted by the mass fraction was about 97%. Compared with pure paraffin, the thermal conductivities of the composite PCMs were drastically enhanced, e.g., the thermal conductivity of the paraffin/nickel foam composite was nearly three times larger than that of pure paraffin. The presence of porous metal foam made the phase change temperatures shift slightly, e.g., the deviations of the peak melting temperatures of the paraffin/nickel foam composite and paraffin/copper foam composite with the pore size of 25PPI from those of pure paraffin were 0.55°C and 0.40°C, respectively.
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water repellent surface Impregnation for extension of service life of reinforced concrete structures in marine environments the role of cracks
Cement & Concrete Composites, 2010Co-Authors: Jianguo Dai, Yoshikazu Akira, F H Wittmann, Hiroshi Yokota, Peng ZhangAbstract:Abstract The enhancement of long-term durability of marine structures is a matter of interest to many researchers. The study presented in this paper examines the effectiveness of a water reducer and chloride barrier surface Impregnation of the concrete cover of reinforced concrete (RC) structures, exposed to a marine environment. Specific focuses is on how surface cracks created (1) before Impregnation and (2) after Impregnation, affect the effectiveness of the surface treatment. The experiments are conducted in an environment which is as close as possible to the real humid subtropical marine environment. A series of reinforced concrete (RC) prisms and concrete cylinders, each treated with various commercial surface Impregnation agents, were exposed to cyclic sea water shower under an outdoor environment to accelerate the dry/wet cycles for 1 year. Six types of surface Impregnation agents, including four types of silane-based water repellent agents and two types of sodium silicate-based pore blockers (water–glass) were applied. Three types of RC prisms were prepared to simulate the different cracking possibilities, which may occur in surface impregnated concrete structures, during their service life. No cracks were introduced in the first prism group, while cracks were introduced before and after surface Impregnation, in the second and third groups, respectively. The time-dependent water absorption of all specimens was monitored during exposure to the dry/wet cycles. Finally the specimens were split open to measure the penetration depths of the surface Impregnation agents and the chloride penetration profiles. The areas with corrosion evident in the steel reinforcement in the RC prisms were also measured. Sodium silicate-based pore blockers were found to be inefficient in preventing chloride penetration of concrete under simulated marine exposures. The long-term efficiency of water repellent agents used for surface Impregnation was found to be highly dependent on the type of agent and whether Impregnation was carried out before or after crack formation.
Suryadi Ismadji - One of the best experts on this subject based on the ideXlab platform.
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high surface area activated carbon prepared from cassava peel by chemical activation
Bioresource Technology, 2006Co-Authors: Yohanes Sudaryanto, Sandy Budi Hartono, Wenny Irawaty, Herman Hindarso, Suryadi IsmadjiAbstract:Abstract Cassava is one of the most important commodities in Indonesia, an agricultural country. Cassava is one of the primary foods in our country and usually used for traditional food, cake, etc. Cassava peel is an agricultural waste from the food and starch processing industries. In this study, this solid waste was used as the precursor for activated carbon preparation. The preparation process consisted of potassium hydroxide Impregnation at different Impregnation ratio followed by carbonization at 450–750 °C for 1–3 h. The results revealed that activation time gives no significant effect on the pore structure of activated carbon produced, however, the pore characteristic of carbon changes significantly with Impregnation ratio and carbonization temperature. The maximum surface area and pore volume were obtained at Impregnation ratio 5:2 and carbonization temperature 750 °C.
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high surface area activated carbon prepared from cassava peel by chemical activation
Bioresource Technology, 2006Co-Authors: Yohanes Sudaryanto, Sandy Budi Hartono, Wenny Irawaty, Herman Hindarso, Suryadi IsmadjiAbstract:Cassava is one of the most important commodities in Indonesia, an agricultural country. Cassava is one of the primary foods in our country and usually used for traditional food, cake, etc. Cassava peel is an agricultural waste from the food and starch processing industries. In this study, this solid waste was used as the precursor for activated carbon preparation. The preparation process consisted of potassium hydroxide Impregnation at different Impregnation ratio followed by carbonization at 450-750 degrees C for 1-3 h. The results revealed that activation time gives no significant effect on the pore structure of activated carbon produced, however, the pore characteristic of carbon changes significantly with Impregnation ratio and carbonization temperature. The maximum surface area and pore volume were obtained at Impregnation ratio 5:2 and carbonization temperature 750 degrees C.
Keiichi Tomishige - One of the best experts on this subject based on the ideXlab platform.
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Surface modification of Ni catalysts with trace Pd and Rh for oxidative steam reforming of methane
Applied Catalysis A: General, 2007Co-Authors: Yuya Mukainakano, Kazu Okumura, Kimio Kunimori, Shigeru Kado, Tomohisa Miyazawa, Toshihiro Miyao, Shuichi Naito, Keiichi TomishigeAbstract:Abstract Bimetallic catalysts (Pd–Ni and Rh–Ni) were prepared by co-Impregnation and sequential Impregnation methods to investigate catalytic performance in oxidative steam reforming of methane. These bimetallic catalysts gave high methane conversion even at low W / F such as 0.07 g h/mol. The thermographical observation clearly demonstrated that the catalyst bed temperature was strongly dependent on the preparation method. The bimetallic catalyst prepared from the sequential Impregnation method exhibited much higher resistance to hot-spot formation in oxidative reforming of methane. In particular, Pd–Ni catalysts prepared by the sequential Impregnation method showed higher resistance to hot-spot formation than monometallic Pd and Ni catalysts, and this can be a synergetic effect of Pd and Ni. Temperature-programmed reduction (TPR) with H 2 revealed that the addition of Pd or Rh by a sequential Impregnation method greatly promoted the reduction of Ni species. Extended X-ray absorption fine structure (EXAFS) analysis confirmed the formation of Pd–Ni alloy and the preferential location of Pd atoms on the surface of the bimetallic particles over the Pd/Ni catalysts. Surface modification of Ni with Pd by sequential Impregnation is effective for promotion of the activity and suppression of hot-spot formation.
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development of ni catalysts for tar removal by steam gasification of biomass
Applied Catalysis B-environmental, 2006Co-Authors: Takeo Kimura, Kazu Okumura, Kimio Kunimori, Shigeru Kado, Tomohisa Miyazawa, Toshihiro Miyao, Shuichi Naito, Jin Nishikawa, Keiichi TomishigeAbstract:Catalytic performance of Ni/CeO2/Al2O3 catalysts prepared by a co-Impregnation and a sequential Impregnation method in steam gasification of real biomass (cedar wood) was investigated. Especially, Ni/CeO2/Al2O3 catalysts prepared by the co-Impregnation method exhibited higher performance than Ni/Al2O3 and Ni/CeO2/Al2O3 prepared by the sequential Impregnation method, and the catalysts gave lower yields of coke and tar, and higher yields of gaseous products. The Ni/CeO2/Al2O3 catalysts were characterized by thermogravimetric analysis, temperature-programmed reduction with H2, transmission electron microscopy and extended X-ray absorption fine structure, and the results suggested that the interaction between Ni and CeO2 became stronger by the co-Impregnation method than that by sequential method. Judging from both results of catalytic performance and catalyst characterization, it is found that the intimate interaction between Ni and CeO2 can play very important role on the steam gasification of biomass.
J A E Manson - One of the best experts on this subject based on the ideXlab platform.
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Impregnation of compressible fiber mats with a thermoplastic resin part ii experiments
Journal of Composite Materials, 2001Co-Authors: Véronique Michaud, R Tornqvist, J A E MansonAbstract:transverse direction is investigated with application to the Glass Mat reinforced Thermoplastics (GMT) lamination process in a double belt press.Amodel proposed in Part I to simulate the kinetics of Impregnation and the evolution of the fiber volume fraction profile as the resin front progresses across the fiber mat, as well as after macro-Impregnation is complete, is further developed to include micro-Impregnation effects. The predictions are compared with experimental results obtained using model systems such as polyethylene glycol and glass fiber mats, as well as an industrially relevant system consisting of polypropylene and glass fiber mats used in the production of GMT blanks. It is shown that significant compression of the fiber mat may occur during Impregnation, with subsequent relaxation on a much longer time-scale. Also, fiber bundle Impregnation generally occurs after macro-Impregnation is complete, the driving force being the local pressure in the resin around the bundles, dictated by the local state of compression of the mat. The model is then used to provide guidelines for optimization of the preform Impregnation conditions for a given material configuration.
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Impregnation technology for thermoplastic matrix composites
Composites Manufacturing, 1992Co-Authors: A. G. Gibson, J A E MansonAbstract:Abstract This paper reviews the technology available for the Impregnation of carbon and glass fibres with thermoplastic resins. Process models and the key material factors influencing the achievement of Impregnation are outlined, then the processes by which Impregnation is currently carried out are discussed. These techniques can be divided into three categories: direct melt, processes where there is intimate mingling of the solid constituents prior to melting of the resin, and operations where low resin viscosities are employed (solvent Impregnation and processes involving reactive chain extension).
Nai Ming Lai - One of the best experts on this subject based on the ideXlab platform.
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comparative efficacy of antimicrobial central venous catheters in reducing catheter related bloodstream infections in adults abridged cochrane systematic review and network meta analysis
Clinical Infectious Diseases, 2017Co-Authors: Huey Yi Chong, Nai Ming Lai, Anucha Apisarnthanarak, Nathorn ChaiyakunaprukAbstract:Background. The efficacy of antimicrobial central venous catheters (CVCs) remains questionable. In this network meta-analysis, we aimed to assess the comparative efficacy of antimicrobial CVC Impregnations in reducing catheter-related infections in adults. Methods. We searched 4 electronic databases (Medline, the Cochrane Central Register of Controlled Trials, Embase, CINAHL) and internet sources for randomized controlled trials, ongoing clinical trials, and unpublished studies up to August 2016. Studies that assessed CVCs with antimicrobial Impregnation with nonimpregnated catheters or catheters with another Impregnation were included. Primary outcomes were clinically diagnosed sepsis, catheter-related bloodstream infection (CRBSI), and all-cause mortality. We performed a network meta-analysis to estimate risk ratio (RR) with 95% confidence interval (CI). Results. Sixty studies with 17 255 catheters were included. The effects of 14 Impregnations were investigated. Both CRBSI and catheter colonization were the most commonly evaluated outcomes. Silver-impregnated CVCs significantly reduced clinically diagnosed sepsis compared with silver-impregnated cuffs (RR, 0.54 [95% CI, .29-.99]). When compared to no Impregnation, significant CRBSI reduction was associated with minocycline-rifampicin (RR, 0.29 [95% CI, .16-.52]) and silver (RR, 0.57 [95% CI, .38-.86]) Impregnations. No Impregnations significantly reduced all-cause mortality. For catheter colonization, significant decreases were shown by miconazole-rifampicin (RR, 0.14 [95% CI, .05-.36]), 5-fluorouracil (RR, 0.34 [95% CI, .14-.82]), and chlorhexidine-silver sulfadiazine (RR, 0.60 [95% CI, .50-.72]) Impregnations compared with no Impregnation. None of the studies evaluated antibiotic/ antiseptic resistance as the outcome. Conclusions. Current evidence suggests that the minocycline-rifampicin-impregnated CVC appears to be the most effective in preventing CRBSI. However, its overall benefits in reducing clinical sepsis and mortality remain uncertain. Surveillance for antibiotic resistance attributed to the routine use of antimicrobial-impregnated CVCs should be emphasized in future trials.
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catheter Impregnation coating or bonding for reducing central venous catheter related infections in adults
Cochrane Database of Systematic Reviews, 2016Co-Authors: Nai Ming Lai, Nathorn Chaiyakunapruk, Nai An Lai, Elizabeth Oriordan, Wilson Shu Cheng Pau, Sanjay SaintAbstract:Background The central venous catheter (CVC) is essential in managing acutely ill patients in hospitals. Bloodstream infection is a major complication in patients with a CVC. Several infection control measures have been developed to reduce bloodstream infections, one of which is Impregnation of CVCs with various forms of antimicrobials (either with an antiseptic or with antibiotics). This review was originally published in June 2013 and updated in 2016. Objectives Our main objective was to assess the effectiveness of antimicrobial Impregnation, coating or bonding on CVCs in reducing clinically-diagnosed sepsis, catheter-related blood stream infection (CRBSI), all-cause mortality, catheter colonization and other catheter-related infections in adult participants who required central venous catheterization, along with their safety and cost effectiveness where data were available. We undertook the following comparisons: 1) catheters with antimicrobial modifications in the form of antimicrobial Impregnation, coating or bonding, against catheters without antimicrobial modifications and 2) catheters with one type of antimicrobial Impregnation against catheters with another type of antimicrobial Impregnation. We planned to analyse the comparison of catheters with any type of antimicrobial Impregnation against catheters with other antimicrobial modifications, e.g. antiseptic dressings, hubs, tunnelling, needleless connectors or antiseptic lock solutions, but did not find any relevant studies. Additionally, we planned to conduct subgroup analyses based on the length of catheter use, settings or levels of care (e.g. intensive care unit, standard ward and oncology unit), baseline risks, definition of sepsis, presence or absence of co-interventions and cost-effectiveness in different currencies. Search methods We used the standard search strategy of the Cochrane Anaesthesia, Critical and Emergency Care Review Group (ACE). In the updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3), MEDLINE (OVID SP; 1950 to March 2015), EMBASE (1980 to March 2015), CINAHL (1982 to March 2015), and other Internet resources using a combination of keywords and MeSH headings. The original search was run in March 2012. Selection criteria We included randomized controlled trials (RCTs) that assessed any type of impregnated catheter against either non-impregnated catheters or catheters with another type of Impregnation in adult patients cared for in the hospital setting who required CVCs. We planned to include quasi-RCT and cluster-RCTs, but we identified none. We excluded cross-over studies. Data collection and analysis We extracted data using the standard methodological procedures expected by Cochrane. Two authors independently assessed the relevance and risk of bias of the retrieved records. We expressed our results using risk ratio (RR), absolute risk reduction (ARR) and number need to treat to benefit (NNTB) for categorical data and mean difference (MD) for continuous data, where appropriate, with their 95% confidence intervals (CIs). Main results We included one new study (338 participants/catheters) in this update, which brought the total included to 57 studies with 16,784 catheters and 11 types of Impregnations. The total number of participants enrolled was unclear, as some studies did not provide this information. Most studies enrolled participants from the age of 18, including patients in intensive care units (ICU), oncology units and patients receiving long-term total parenteral nutrition. There were low or unclear risks of bias in the included studies, except for blinding, which was impossible in most studies due to the catheters that were being assessed having different appearances. Overall, catheter Impregnation significantly reduced catheter-related blood stream infection (CRBSI), with an ARR of 2% (95% CI 3% to 1%), RR of 0.62 (95% CI 0.52 to 0.74) and NNTB of 50 (high-quality evidence). Catheter Impregnation also reduced catheter colonization, with an ARR of 9% (95% CI 12% to 7%), RR of 0.67 (95% CI 0.59 to 0.76) and NNTB of 11 (moderate-quality evidence, downgraded due to substantial heterogeneity). However, catheter Impregnation made no significant difference to the rates of clinically diagnosed sepsis (RR 1.0, 95% CI 0.88 to 1.13; moderate-quality evidence, downgraded due to a suspicion of publication bias), all-cause mortality (RR 0.92, 95% CI 0.80 to 1.07; high-quality evidence) and catheter-related local infections (RR 0.84, 95% CI 0.66 to 1.07; 2688 catheters, moderate quality evidence, downgraded due to wide 95% CI). In our subgroup analyses, we found that the magnitudes of benefits for impregnated CVCs varied between studies that enrolled different types of participants. For the outcome of catheter colonization, catheter Impregnation conferred significant benefit in studies conducted in ICUs (RR 0.70;95% CI 0.61 to 0.80) but not in studies conducted in haematological and oncological units (RR 0.75; 95% CI 0.51 to 1.11) or studies that assessed predominantly patients who required CVCs for long-term total parenteral nutrition (RR 0.99; 95% CI 0.74 to 1.34). However, there was no such variation for the outcome of CRBSI. The magnitude of the effects was also not affected by the participants' baseline risks. There were no significant differences between the impregnated and non-impregnated groups in the rates of adverse effects, including thrombosis/thrombophlebitis, bleeding, erythema and/or tenderness at the insertion site. Authors' conclusions This review confirms the effectiveness of antimicrobial CVCs in reducing rates of CRBSI and catheter colonization. However, the magnitude of benefits regarding catheter colonization varied according to setting, with significant benefits only in studies conducted in ICUs. A comparatively smaller body of evidence suggests that antimicrobial CVCs do not appear to reduce clinically diagnosed sepsis or mortality significantly. Our findings call for caution in routinely recommending the use of antimicrobial-impregnated CVCs across all settings. Further randomized controlled trials assessing antimicrobial CVCs should include important clinical outcomes like the overall rates of sepsis and mortality.
