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51.
A colorimetric assay for the quantitative determination of nonenzymatically glucosylated proteins is presented. The method employed is a modification of the method of Massamiri et al. (1978, Anal. Biochem., 91, 618–625) for quantitating sialic acid residues. The procedure involves periodate oxidation of the glucosylated protein releasing formaldehyde. The latter is then detected by complexing with the reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH). Fructose is used as a standard as it is structurally analogous to the ketoamine form on the protein. The MBTH assay can accurately detect fructose in concentrations as low as 1 μM. The assay was utilized to quantitate in vitro nonenzymatically glucosylated calmodulin and bovine serum albumin. 相似文献
52.
Antitumor drugs may have some significant nervous system side-effects such as disrupted sleep, eating and drinking patterns. European Mistletoe has been investigated for many decades for its potential use against cancer. To test the hypothesis that the non-antineoplastic effects of mistletoe might be mediated by the actions on the circadian timing system, we have applied mistletoe extracts and vehicle and have measured locomotor activity, feeding and drinking rhythms under constant darkness. Four groups (vehicle, 20 mg kg(-1) ip injection, 40 mg kg(-1) ip injection and 6 g kg(-1) oral administration) were performed for both heat-treated and freeze-dried extracts. None of the administrations changed the locomotor activity, feeding and drinking rhythms in the groups except for 40 mg kg(-1) freeze-dried injected group. The locomotor activity levels decreased in 40 mg kg(-1) freeze-dried extract injected group. These results suggest that, side-effects of mistletoe on circadian timing system of the Syrian hamster depend on the dose and the preparation method of the extract. 相似文献
53.
Kozarova A Sliskovic I Mutus B Simon ES Andrews PC Vacratsis PO 《Journal of the American Society for Mass Spectrometry》2007,18(2):260-269
Regulation of the redox state of protein disulfide isomerase (PDI) is critical for its various catalytic functions. Here we describe a procedure utilizing isotope-coded affinity tag (ICAT) technology and mass spectrometry that quantitates relative changes in the dynamic thiol and disulfide states of human PDI. Human PDI contains six cysteine residues, four present in two active sites within the a and a' domains, and two present in the b' domain. ICAT labeling of human PDI indicates a difference between the redox state of the two active sites. Furthermore, under auto-oxidation conditions an approximately 80% decrease in available thiols within the a domain was detected. Surprisingly, the redox state of one of the two cysteines, Cys-295, within the b' domain was altered between the fully reduced and the auto-oxidized state of PDI while the other b' domain cysteine remained fully reduced. An interesting mono- and dioxidation modification of an invariable tryptophan residue, Trp-35, within the active site was also mapped by tandem mass spectrometry. Our findings indicate that ICAT methodology in conjunction with mass spectrometry represents a powerful tool to monitor changes in the redox state of individual cysteine residues within PDI under various conditions. 相似文献
54.
An amperometric biosensor based on horseradish peroxidase (HRP) and carbon nanotube (CNT)/polypyrrole (PPy) nanobiocomposite film on a gold surface has been developed. The HRP was incorporated into the CNT/PPy nanocomposite matrix in one-step electropolymerization process without the aid of cross-linking agent. Amperometric response was measured as a function of concentration of phenol derivatives, at a fixed bias voltage of -50 mV. Optimization of the experimental parameters was performed with regard to pH and concentration of hydrogen peroxide. The linear range, sensitivity and detection limit of the biosensor were investigated for eighteen phenol derivatives. The sensitivity in the linear range increased in this order: 4-methoxyphenol>2-aminophenol>guaiacol=m-cresol>2-chlorophenol=4-chlorophenol=hydroquinone=pyrocatechol>2,6-dimethoxyphenol>3-chlorophenol>p-cresol>p-benzoquinone=4-acetamidophenol>catechol>phenol=pyrogallol=2,4-dimethylphenol. CNTs was shown to enhance the electron transfer as a mediator and capable to carry higher bioactivity owing to its intensified surface area. The biosensor exhibited low detection limits with a short response time (2s) for the tested phenolics compared to the reported working electrodes. It retained 70% of its initial activity after using for 700 measurements in 1 month. 相似文献
55.
Pamukoglu M. Yunus Kirkan Bulent Senyurt Mustafa 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(1):343-352
The biosorption of radioactive Th(IV) ions in the aqueous solutions onto the modified powdered waste sludge (MPWS) has been examined. In this context, the parameters affecting biosorption of Th(IV) from aqueous solutions has been examined by using MPWS biosorbent in Box Behnken statistical experimental design. The structure of MPWS biosorbent was characterized by using SEM and BET techniques. According to the experimental design results, MPWS and Th(IV) concentrations should be kept high to achieve the maximum efficiency in Th(IV) biosorption. On the other hand, MPWS, which is also used as a biosorbent, is an economical, effective and natural biosorbent.
相似文献56.
57.
Thickness of the thermal boundary layer on natural convection from a horizontal plate was experimentally measured and expressed
as a function of Rayleigh number both in laminar and turbulent regimes. Several parametric equations expressing the Nusselt
number as a function of Rayleigh number were developed combining experimental data by other authors with the ones obtained
in this work. The characteristic length was taken as the thickness of the thermal boundary layer in one equation and as the
ratio of the area to the perimeter in another one. Both characteristic lengths correlated the data precisely in wide ranges
of Rayleigh numbers.
相似文献
Bulent KozanogluEmail: |
58.
Arzu Aydogan Yenmez Ayhan Kursat Erbas Erdinc Cakiroglu Cengiz Alacaci Bulent Cetinkaya 《International Journal of Mathematical Education in Science & Technology》2017,48(6):895-912
Applications and modelling have gained a prominent role in mathematics education reform documents and curricula. Thus, there is a growing need for studies focusing on the effective use of mathematical modelling in classrooms. Assessment is an integral part of using modelling activities in classrooms, since it allows teachers to identify and manage problems that arise in various stages of the modelling process. However, teachers’ difficulties in assessing student modelling work are a challenge to be considered when implementing modelling in the classroom. Thus, the purpose of this study was to investigate how teachers’ knowledge on generating assessment criteria for assessing student competence in mathematical modelling evolved through a professional development programme, which is based on a lesson study approach and modelling perspective. The data was collected with four teachers from two public high schools over a five-month period. The professional development programme included a cyclical process, with each cycle consisting of an introductory meeting, the implementation of a model-eliciting activity with students, and a follow-up meeting. The results showed that the professional development programme contributed to teachers’ knowledge for generating assessment criteria on the products, and the observable actions that affect the modelling cycle. 相似文献
59.
Zeynep Yilmazer Hitit Havva Boyacioglu Baran Ozyurt Suna Ertunc Hale Hapoglu Bulent Akay 《Applied biochemistry and biotechnology》2014,172(8):3761-3775
A detailed system identification procedure and self-tuning generalized minimum variance (STGMV) control of glucose concentration during the aerobic fed-batch yeast growth were realized. In order to determine the best values of the forgetting factor (λ), initial value of the covariance matrix (α), and order of the Auto-Regressive Moving Average with eXogenous (ARMAX) model (n a, n b), transient response data obtained from the real process wereutilized. Glucose flow rate was adjusted according to the STGMV control algorithm coded in Visual Basic in an online computer connected to the system. Conventional PID algorithm was also implemented for the control of the glucose concentration in aerobic fed-batch yeast cultivation. Controller performances were examined by evaluating the integrals of squared errors (ISEs) at constant and random set point profiles. Also, batch cultivation was performed, and microorganism concentration at the end of the batch run was compared with the fed-batch cultivation case. From the system identification step, the best parameter estimation was accomplished with the values λ?=?0.9, α?=?1,000 and n a?=?3, n b?=?2. Theoretical control studies show that the STGMV control system was successful at both constant and random glucose concentration set profiles. In addition, random effects given to the set point, STGMV control algorithm were performed successfully in experimental study. 相似文献
60.
Frontiers of Physics - Graphene oxide (GO), the functionalized graphene with oxygenated groups (mainly epoxy and hydroxyl), has attracted resurgent interests in the past decade owing to its large... 相似文献