Fabricating Nanogaps by Nanoskiving

There are several methods of fabricating nanogaps with controlled spacings, but the precise control over the sub-nanometer spacing between two electrodes-and generating them in practical quantities-is still challenging. The preparation of nanogap electrodes using nanoskiving, which is a form of edge lithography, is a fast, simple and powerful technique. This method is an entirely mechanical process which does not include any photo- or electron-beam lithographic steps and does not require any special equipment or infrastructure such as clean rooms. Nanoskiving is used to fabricate electrically addressable nanogaps with control over all three dimensions; the smallest dimension of these structures is defined by the thickness of the sacrificial layer (Al or Ag) or self-assembled monolayers. These wires can be manually positioned by transporting them on drops of water and are directly electrically-addressable; no further lithography is required to connect them to an electrometer.     

Immobilization of lipases onto the SBA-15 mesoporous silica

Lipase is an important enzyme which can catalyse the hydrolysis of lipids and has several applications and industrial potentials. In addition, different types of lipases are used as efficient catalysts in the enantioselective esterification and/or hydrolysis reactions and produce products in high yields and enantio excess as well. However, immobilization of lipases on the surface of a heterogeneous substrate is necessary to improve its specific catalytic activities as it can be isolated from the reaction mixture easily. Mesoporous silica materials are the best option for this aim due to their high specific surface area, ordered structure, and large pore volume. Hence, in this article, the role of SBA-15 and the modified SBA-15 mesoporous materials as support for different lipases and their catalytic activities are reviewed.     

Towards a Better Treatment Option for Parkinson’s Disease: A Review of Adult Neurogenesis

The motor symptoms of Parkinson’s disease (PD) are caused by degeneration of dopamine (DA) neurons in the substantia nigra pars compacta (SNc) of midbrain. Given the fact that current treatment options are mostly symptomatic and based on increasing DA level in the nigrostriatal system, it is generally believed the most effective and long-lasting treatment for PD motor symptoms will be replacing SNc DA cells, either by endogenous repair (i.e. neurogenesis) or cell transplantation. While cell transplantation is hindered by failure of acquisition and maintenance of the DA phenotype by transplanted cells, hope rests upon non-invasive cell replacement therapy (CRT) with endogenous neural stem cells, which have the potential to give rise to new neurons including DA neurons. Understanding underlying mechanisms and signalling pathways of neurogenesis in the adult brain could shed light on obstacles to achieve effective CRTs and better treatments for PD. This paper first reviews different therapeutic strategies in context of PD along with their advantages and disadvantages followed by an extensive review of adult neurogenesis.     

Uptake of Re(VII) from aqueous solutions by Bacillus sp. GT-83-23

Thirty-eight water samples were collected from various areas of Anzali lagoon, Iran. Initial screening of a total of 100 bacterial isolates, resulted in the selection of one isolate with maximum adsorption capacity. It was tentatively identified as Bacillus sp. and named strain GT-83-23. The optimum pH of the medium was found to be 2.0 for Re(VII) adsorption. Uptakes of Re(VII) increased with increasing Re(VII) concentration and decreased sharply by the presence of increasing concentrations of NaCl. The kinetic of Re(VII) sorption by Bacillus sp. GT-83-23 was fast, reaching more than 62% of the total sorption capacity within 5 min. As the cell concentration increased, the amount of Re(VII) adsorbed by each cell (specific uptake) decreased, whereas the total amount of Re(VII) adsorbed enhanced. Cells immobilized in calcium alginate gel took up 77% of the Re(VII). The binding of Re(VII) on the Bacillus sp. GT-83-23 was studied with micro-PIXE.     

Plant growth promotion and suppression of <Emphasis Type="Italic">Phytophthora drechsleri</Emphasis> damping-off in cucumber by cellulase-producing <Emphasis Type="Italic">Streptomyces</Emphasis>

Phytophthora drechsleri damping-off is one of the most important diseases of cucumber (Cucumis sativus). Salinity is a serious problem for crop production and affects diversity and activity of soil microorganisms. Application of salt-tolerant biocontrol agents may be beneficial in order to protect plants against pathogenic fungi in saline soils. In this study, a total of 717 Streptomyces isolates were isolated from the rhizosphere of cucumber, out of which two isolates showed more than 70% inhibitory effect against P. drechsleri and had cellulase activity in the presence and absence of NaCl. In a greenhouse experiment, two Streptomyces isolates with the highest antagonistic activity, strains C 201 and C 801, reduced seedling damping-off of cucumber caused by P. drechsleri by 77 and 80%, respectively, in artificially infested soils. Strain C 201 increased dry weight of seedlings up to 21% in greenhouse experiments. Phylogenetic analyses of 16S rRNA gene sequence reveals that strains C 201 and C 801 are closely related to S. rimosus and S. monomycini respectively. Increased activity of polyphenol oxidase (PPO) and peroxidase (POX) enzymes in Streptomyces-treated plants proved the biocontrol-induced systemic resistance (ISR) in cucumber plants against P. drechsleri.     

Noninnocent effect of axial ligand on the heme degradation process: a theoretical approach to hydrolysis pathway of verdoheme to biliverdin

Conversion of iron(II) verdoheme to iron(II) biliverdin in the presence of hydroxyl ion as a nucleophile and imidazole, pyridine, water, hydroxyl, cyanide, phenolate, chloride, thiolate and imidazolate as axial ligands was investigated using the B3LYP method and the 6-31G basis set. In the five-coordinated pathway the reactants and products are in the ground triplet state. In this path, hydroxyl ion directly attacks the macrocycle. The exothermic energy for addition of hydroxyl ion to iron(II) verdoheme with various ligands is 169.55, 166.34 and 164 kcal mol⁻¹ for water, pyridine and imidazole, energies which are around 30–60 kcal mol⁻¹ more exothermic than those for the other axial ligands used in this study. Therefore, imidazole, water and pyridine axial ligands can facilitate hydrolytic cleavage of iron(II) verdoheme to form open-chained helical iron(II) biliverdin complexes. The activation barrier for the conversion of iron(II) verdoheme hydroxyl species to the iron(II) biliverdin complex is estimated to be 5.2, 4.2, 4.35, 13.76 and 14.05 kcal mol⁻¹ for imidazole, water, cyanide, thiolate and imidazolate, respectively. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.