Magnetic layered double hydroxide nanosheet as a biomolecular vessel for enzyme immobilization.

Magnetic nanoparticle coated with manganese­aluminum layered double hydroxide (Fe3O4/Mg-Al-CO3-LDH) was prepared and used as porous support for ficin (EC 3.4.22.3) as a model enzyme. Structural characteristics were studied by XRD, FTIR, SEM and light scattering. The quantity of immobilized ficin on the mentioned LDH and non-magnetic LDH was measured and enzyme activity, stability and reusability were compared. Results revealed that the core and shell structure of Fe3O4/Mg-Al-CO3-LDH makes it better dispersion compared to the pristine Mg-Al-CO3-LDH. Ficin showed strong affinity to absorption of the surface of mentioned LDHs nanosheet especially magnetic LDH, confirmed that the existence of Fe3O4 in the core structure of magnetic Fe3O4/Mg-Al-CO3-LDH caused better dispersion of LDH nanocrystal shell compared to pristine LDH moreover, enzyme which immobilized on the magnetic LDH supports, can be recovered by magnetic interaction. The storage stability of free ficin, immobilized ficin on the Mg-Al-CO3-LDH and Fe3O4/Mg-Al-CO3-LDH during a period of 120 days lost about 75%, 30%, and 20% of their initial activities, respectively.

Facile preparation of covalently functionalized graphene with 2,4-dinitrophenylhydrazine and investigation of its characteristics.

This article reports a fast and easy method for simultaneously in situ reducing and functionalizing graphene oxide. 2,4-Dinitrophenylhydrazine hydrate salt molecules are reduced by graphene oxide by reacting with oxide groups on the surface and removing these groups, and 2,4-dinitrophenylhydrazone groups are replaced with oxide groups. The synthesized materials have been investigated using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and UV absorption. Also, the morphology has been examined with a scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) analysis. The result of the photocurrent response and electrochemical behavior of the samples through cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) have been analyzed to investigate the effect of physical and chemical changes compared to graphene.

The Effect of Baseline Performance and Age on Cognitive Training Improvements in Older Adults: A Qualitative Review.

Findings that the brain is capable of plasticity up until old age have led to interest in the use of cognitive training as a potential intervention to delay the onset of dementia. However, individuals participating in training regimens differ greatly with respect to their outcomes, demonstrating the importance of considering individual differences, in particular age and baseline performance in a cognitive domain, when evaluating the effectiveness of cognitive training. In this review, we summarize existing literature on cognitive training in adults across the domains of episodic memory, working memory and the task-switching component of executive functioning to clarify the picture on the impact of age and baseline performance on cognitive training-related improvements. Studies targeting episodic memory induced greater improvements in younger adults with more intact cognitive abilities, explained in part by factors specific to episodic memory training. By contrast, older, lower baseline performance adults improved most in several studies targeting working memory in older individuals as well as in the majority of studies targeting executive functioning, suggesting the preservation of neural plasticity in these domains until very old age. Our findings can have important implications for informing the design of future interventions for enhancing cognitive functions in individuals at the prodromal stage of Alzheimer's Disease and potentially delaying the clinical onset of Alzheimer's Disease. Future research should more clearly stratify individuals according to their baseline cognitive abilities and assign specialized, skill-specific cognitive training regimens in order to directly answer the question of how individual differences impact training effectiveness.

Characterization of Leishmania isolated from unhealed lesions caused by leishmanization.

Leishmania parasites were isolated after 13 and 8 years from the unhealed lesions of 2 soldiers who had been immunized against leishmaniasis during the war between Iraq and the Islamic Republic of Iran. Isoenzyme characterization on these isolates using 11 enzyme systems was carried out and the results were compared with the enzyme profiles of the original isolates of L. major used for leishmanization. Minor enzymatic differences in glucose-6-phosphate dehyrognase and phosphoglucomutase were observed but otherwise the strains appeared unchanged.