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Glucose isomerase (GI) from Streptomycesrubiginosus was immobilized covalently onto Eupergit C 250 L made by copolymerization of N,N-methylene-bis-methacrylamide, glycidyl methacrylate, allyl glycidyl ether and methacrylamide. The catalytic efficiency of immobilized GI in isomerization of glucose to fructose was found as three fold higher than that of free GI. The residual activity of immobilized GI after 18 reuses in a batch type stirred reactor was about 85% of its initial activity. The thermal stability of immobilized GI was almost same with that of the free GI at 60 °C for 18 h preincubation time. The residual activities of immobilized GI when stored at 5 °C and 25 °C for four weeks were 72% and 69% of the initial activity, respectively. However, free GI retained 88% and 78% of its initial activity at 5 °C and 25 °C upon four weeks storage, respectively. Thus, the use of Eupergit C 250 L immobilized GI instead of free GI is suggested in enzymatic isomerization of glucose to fructose. 相似文献
3.
Influence of using as catalysis, Ni-Schiff Base complex which we previously synthesized [1] used to support with amberzyme oxirane resin (A.O.R.) polymer for increasing the catalytic activity in NaBH4 hydrolysis reaction, to hydrogen generation was studied. The prepared catalyst was characterized by using SEM, XRD, BET, FT-IR analyze technique. Polymer supported Ni-Schiff Base complex catalyzed NaBH4 hydrolysis reaction was investigated depending on concentration of NaBH4, concentration of NaOH, temperature, percentage of Ni complex in total polymer supported Ni-Schiff Base complex and amount of catalyst factors. The maximum hydrogen production rate from hydrolysis of sodium borohydride with nickel-based complex catalyst compared to the pure nickel catalyst is increased from 772 mL H2·g?1 cat.·min?1 to 2240 mL H2 g?1 cat.·min?1 [1], and with supported amberzyme oxirane resin polymer this nickel based complex catalyst was increased to 13000 mL H2·g?1 cat.·min?1 at 30 °C. The activation energy of complex catalyzed NaBH4 hydrolysis reaction was found as 25.377 kJ/mol. This work also includes kinetic information for the hydrolysis of NaBH4. 相似文献
4.
Dilek U. Duman Stuart D. Green Graeme D. Larsen 《Construction Management & Economics》2019,37(7):367-383
The Turkish contracting sector has an enviable reputation for operating in high-risk international markets. The sector’s ability to respond to market instability could meaningfully be construed as sectoral-level capability. We aim to demonstrate how history can be mobilised in a formalised “strategy text” to create a strategic narrative on the sectoral level. The Geography of Contractors as published by the Turkish Contractors Association (TCA) ostensively portrays the strategic development of Turkish international contractors over four decades. Such quasi-historical narratives are routinely mobilised for the purposes of creating a shared memory on the sectoral level. The chosen strategy text draws from multiple narrative fragments derived from past experience to generate a strategic agenda for the future. The representation given to multiple voices reflects the pluralistic nature of strategy making praxis. The overarching strategy narrative reflects a performative intent in legitimising some practices whilst discrediting others. Narrative analysis demonstrates the way in which actors, actions and events are positioned within a plot structure, with direct implications for the enactment of future strategic practices. The findings suggest that strategic actions can only ever be identified in retrospect and that such arguments are always made with an eye on the future. 相似文献
5.
Selenium, copper, nickel, zinc, cadmium, manganese, iron, copper and lead contents of certain fish, meat and meat products consumed in Turkey were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). The order of the elements in the meat, meat products and fish samples and their concentration ranges in μg 100 g−1 was Fe (57.7–156.4) > Zn (20–159) > Ni (8.2–24) > Pb (11.5–13.5) > Cr (8.44–9.51) > Cu (7.18–10.01) > Cd (0.77–1.04) > Mn (3.98–10) > Se (1.32–4.6). The elemental concentrations of fish studied seemed to be close to the international standards. The highest trace element concentrations were obtained from past?rma, meat and sausage while the lowest value was observed in Trachurus trachurus (saurel). Iron concentrations in all samples were higher than the recommended values. 相似文献
6.
Ufuk Dilek 《Canadian Metallurgical Quarterly》2007,21(5):337-344
This paper discusses applications of ASTM C 597 “Standard Test Method for Pulse Velocity Through Concrete” technique to field detection of damage to concrete in service and field quality assessment of cast-in-place concrete and masonry under construction. Four unique field investigation and validation studies are discussed in this paper. The first part includes field assessments of concrete members under construction with questionable quality. Case studies include detection of zones of high air content and low strength concrete in a cast-in-place, posttensioned structure and detection of voids and honeycombs in poorly consolidated cast-in-place beams. The third case study pertinent to construction involves detection of poorly consolidated collar joints in a masonry rehabilitation project. In addition to assessments during construction and rehabilitation, this paper also discusses assessment of damage to concrete structures in service. The case study included in the paper involves exposure to elevated temperatures during a fire at a precast, double tee concrete parking structure. Nondestructive evaluation (NDE) testing findings were validated by subsequent laboratory testing or selective demolition to confirm NDE findings. This paper should be of value to practicing engineers interested in application of pulse velocity testing technique in field assessments similar to ones discussed. This paper should also be of value to researchers interested in applicability of pulse velocity to research concerning properties of concrete subjected to the damage mechanisms associated with elevated temperatures. 相似文献
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Nermin Tansuğ Muzaffer Polat Selcan Çeşme Fatma Taneli Salih Gözmen Özlem Tokuşoğlu Dilek Yılmaz Gönül Dinç 《Nutrition journal》2010,9(1):34
Background
Vitamin A deficiency is a major public health nutrition problem in the developing world. Even subclinical Vitamin A deficiency is associated with increased childhood mortality. Severe maternal vitamin A deficiency may cause increased mortality in the first months of life. There have been a limited number of studies regarding vitamin A status in Turkey. The aim of this study was to assess vitamin A status of healthy children in Manisa, Turkey. 相似文献9.
Srinivas Peeta F. Sibel Salman Dilek Gunnec Kannan Viswanath 《Computers & Operations Research》2010,37(10):1708-1719
We address a pre-disaster planning problem that seeks to strengthen a highway network whose links are subject to random failures due to a disaster. Each link may be either operational or non-functional after the disaster. The link failure probabilities are assumed to be known a priori, and investment decreases the likelihood of failure. The planning problem seeks connectivity for first responders between various origin–destination (O–D) pairs and hence focuses on uncapacitated road conditions. The decision-maker's goal is to select the links to invest in under a limited budget with the objective of maximizing the post-disaster connectivity and minimizing traversal costs between the origin and destination nodes. The problem is modeled as a two-stage stochastic program in which the investment decisions in the first stage alter the survival probabilities of the corresponding links. We restructure the objective function into a monotonic non-increasing multilinear function and show that using the first order terms of this function leads to a knapsack problem whose solution is a local optimum to the original problem. Numerical experiments on real-world data related to strengthening Istanbul's urban highway system against earthquake risk illustrate the tractability of the method and provide practical insights for decision-makers. 相似文献
10.
Summary
Macromonomeric peroxy initiator, poly tetrahydrofuran (poly-THF=inimer) were synthesized via cationic polymerization of THF
by the mono- (t-BuBP) and tetra-bromo methyl benzoyl peroxides (BDBP)/ZnCl2 initiating system. The macromonomers were characterized by 1H-NMR, IR, and GPC techniques. Methyl methacrylate (MMA) polymerization initiated by poly-THF inimers at 80°C and different
times in bulk gave crosslinked poly-THF-b-polymethyl methacrylate block copolymers. Swelling ratios of the crosslinked block
copolymers obtained by taking in same amounts of poly-THF inimer and MMA monomer in CHCl3 were decreased versus time. It was compared the results obtained from t-BuBP-, BDBP-ZnCl2 initiating systems with t-BuBP-, BDBP-AgSbF6 initiating systems for THF monomer. Poly(THF-b-MMA) crosslinked block copolymers containing undecomposed peroxide groups
initiated the thermal polymerization of styrene, S, were used to obtain poly(THF-b-MMA-b-S) crosslinked multicomponent copolymers at 90°C. The crosslinked multi component copolymers were investigated sol-gel
analysis and swelling ratios in CHCl3. "Active" poly(THF-b-MMA) having peroxygen group were used in the free radical coupling reaction of poly butadien (Poly Bd). Poly(THF-b-MMA)-polybutadien crosslinked blend soluble graft copolymers were obtained.
Received: 31 July 2001/Revised version: 16 June 2002/ Accepted: 5 July 2002 相似文献