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Sharp one-dimensional (1D) and two-dimensional (2D) structures are required for stable and efficient field emission. 1D metal oxide and 1D carbonaceous nanostructure material have been used widely for exciting field emission applications. On the other hand, planar, continuous 2D nanostructures have been less explored, as most often, they offer inefficient field emitters, having high turn-on field and low emission current density. A combination of 1D and 2D nanostructures is expected to improve field emission properties. In the present study, nickel oxide nanostructures were considered as 1D nanostructures, which were synthesized on cleaned, polished, nickel foil substrate by wet chemical treatment through the nano-seed mechanism. Pyramidal shape nanostructures of NiO were found onto nickel substrate. 1D nanostructure, NiO nanostructure, does not show any field emission response. Further, graphene oxide (GO) was used as the 2D nanostructure.) While nickel oxide nanostructure and graphene oxide individually demonstrated very low emission properties, hybrid of these materials show modified surface topography and enhanced field emission properties. The field emission response of graphene oxide on Ni foil shows 6.7 V/μm turn-on field and maximum current density of 28 µA/cm2, whereas graphene oxide on NiO nanostructure has enhanced field emission response. In the case of NiO–GO, the turn-on field and maximum current are 5 V/μm and 173 µA/cm2, respectively. Field emission properties are enhanced further with the reduction of the NiO–GO hybrid and depositing CNT of NiO. The maximum current density of 3.7 mA/cm2was observed for the NiO–CNT hybrid.

Attractive attributes of carbon nanotubes (CNTs),, which include high aspect ratio, excellent electrical and thermal conductivity, high melting point, and longer lifetime, have made this one-dimensional material a promising candidate for next-generation field emitters. In the present work, CNTs were grown directly on copper foil, copper foam, nickel foil and nickel foam through chemical vapor deposition. A comparison between CNT-based two-dimensional emitters, i.e. CNTs synthesized on copper and nickel foils, CNT-based three-dimensional (3D) emitters, i.e. CNTs developed on foams of copper and nickel, have been demonstrated. We observed that CNTs on foams exhibited better field emission compared to CNTs synthesized on foils. This is due to the multistage structure of the 3D foams which provides high surface area for CNT growth and hence enhanced field emission response. In the present work, a CNT sample prepared on nickel foam was observed to exhibit better field emission response compared to the other samples synthesized in the present study. This particular sample demonstrateda very low turn-on field of 0.93 V/µm, excellent field enhancement factor of 13,343 and good stability of electron emission.

Graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO) are the potential candidates for high-performance field emission devices owing to their unique geometry and electrical properties. However, flat surface of GO and rGO results in lower field emission efficiency due to emission of electrons only from sharp edges of GO and rGO sheets. In the present study, GO and rGO layers were deposited on both CuO and Cu nanorods (NRs) to enable maximum field emission current density at low applied field via geometrical field enhancement. CuO NRs were synthesized on Cu foil using wet chemical method and Cu NRs were produced through chemical and thermal reduction of CuO NRs. GO layers were deposited on CuO and Cu NRs through dip coating method. GO was converted to rGO through thermal reduction. A comparative study of the field emission properties of CuO, GO@CuO, rGO@CuO, Cu_H 2, GO@Cu_H2, rGO@Cu_H2, Cu_NaBH4, GO@Cu_NaBH4, rGO@Cu_NaBH4 samples was performed. The basic idea behind deposition of GO and rGO sheets on CuO and Cu NRs was to create sharp protrusions in GO and rGO sheets to achieve enhanced field emission properties. Local field enhancement at the apex of sharp protrusions allows tunneling and hence emission of electrons from tips at considerable lower voltage. Highest current density and highest field enhancement factor were obtained in thermally reduced GO@CuO (i.e rGO@CuO) sample.

A two-step, low-temperature thermal chemical vapor deposition (CVD) process, which uses camphor for synthesizing continuous graphene layer on Cu substrate is reported. The growth process was performed at lower temperature (800 °C) using camphor as the source of carbon. A threezone CVD system was used for controlled heating of precursor, in order to obtain uniform graphene layer. As-grown samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The results show the presence of 4–5 layers of graphene. As-grown graphene transferred onto a glass substrate through a polymer-free wet-etching process, demonstrated transmittance ~91% in visible spectra. This process of synthesizing large area, 4–5 layer graphene at reduced temperature represents an energy-efficient method of producing graphene for possible applications in opto-electronic industry.

Depression is multi-factorial in origin and results from intricate mechanisms with no single identifiable risk factor. The present study is a cross-sectional study, conducted among 808 participants aged 30–70 years from a single mendelian, largely vegetarian population from North India. Socio- demographic and depression status were assessed through standard interview schedule among recruited individuals. Chemi- luminescence Immunoassay technique by Immulite®1000 is used to analyse homocysteine, folate and vitamin B12 levels. Of the total studied subjects, 31.1% were found to be having depression with higher rate among females (35.7%) compared to males (24.6%) (p = 0.002). Hyperhomocysteinemia and folate deficiency were found to pose an increased risk for moderate/ severe depression, though not significant. Folate repletion was playing a compensatory role for vitamin B12 deficiency among depressed individuals. MTHFR C677T gene polymorphism was not associated with depression in the present study.

A variety of CuO nanostructures have been synthesized directly on copper foils by room temperature oxidation of copper through wet chemical method. Alkaline condition necessary for the growth process was maintained by the application of NaOH and NH3 precursors. pH of the solution and reaction time were selected as the process variables. Formation of CuO was confirmed by X-ray diffraction pattern analysis. Evolution of morphologies of the phases formed was characterized by field emission scanning electron microscopy, leading to elucidation of the growth mechanism. Different types of CuO nanostructures were observed to be formed at different process parameters, selected for the present study. Field emission characteristics of CuO nanorods and CuO nanoflakes were also investigated. Emission current density of CuO nanorods and CuO nanoflakes were determined to be 0.90 mA/cm2 and 0.48 mA/cm2, respectively. Huge difference in the emission current density indicates that field emission properties of CuO nanostructures are strongly affected by their morphology.

Field emission is a process of electron emission from the surface of a material through quantum tunneling in the presence of an applied electric field. Emission of electrons from a material becomes easy if material is synthesized in the form of nanoscale sharp tips. In the present work, we synthesized one dimensional nanostructures (1-D) such as copper oxide (CuO) nanorods and carbon nanotubes (CNTs) by wet chemical and chemical vapor deposition (CVD) methods, respectively. As the electron field emission (FE) from the flat surface of graphene is challenging, the reduced graphene oxide (RGO) was coated on CuO nanorods and CNTs to prepare RGO based hybrids for field emission. Basic idea to support RGO on 1-D nanostructures was to produce high density sharp protrusions/ridges in RGO sheets. A comparison between the FE characteristics of 1-D nanostructures and RGO based hybrid emitters was performed.

Recent data suggest that intraneuronal accumulation of metabolites of the amyloid β precursor protein (APP) is neurotoxic. We observed that transgenic mice overexpressing in neurons a human APP gene harboring the APPE693Q (Dutch) mutation have intraneuronal lysosomal accumulation of APP carboxyl-terminal fragments (APP-CTFs) and oligomeric amyloid β (oAβ) but no histological evidence of amyloid deposition. Morphometric quantification using the lysosomal marker protein 2 (LAMP-2) immunolabeling showed higher neuronal lysosomal counts in brain neurons of 12 months old APPE693Q as compared to age-matched non-transgenic littermates, and Western blots showed increased lysosomal proteins including LAMP-2, cathepsin D and LC3. At 24 months of age, these mice also exhibited an accumulation of α-synuclein in the brain, along with increased conversion of LC3-I to LC3-II, an autophagosomal/autolysosomal marker. In addition to lysosomal changes at 12 months of age, these mice developed cholinergic neuronal loss in the basal forebrain, GABAergic neuronal loss in the cortex, hippocampus and basal forebrain, and gliosis and microgliosis in the hippocampus. These findings suggest a role for the intraneuronal accumulation of oAβ and APP-CTFs and resultant lysosomal pathology at early stages of Alzheimer’s disease-related pathology.

The present study aims to investigate the role of Global DNA Methylation in Depression. A total of 368 individuals (118 males and 250 females) were screened for depression using PHQ9 (Patient Health Questionnaire 9) and 5-mc% (5-methyl cytosine) content of Peripheral Leucocytes DNA was measured by enzyme linked calorimetric based MethyFlash™ methylated DNA quantification kit. Among individuals with depression a lower Global DNA methylation (though not significant) in terms of 5-mc% (5-methyl cytosine) content was observed compared to individuals without depression.

Carbon nanotubes (CNTs) were directly grown on copper and nickel foams by chemical vapor deposition (CVD) process, followed by the deposition of reduced graphene oxide (rGO) through dip-coating method. These three-dimensional hybrid structures were used as cold cathodes to perform field emission tests under DC bias application. Field emission response of CNTs grown on metallic foams was compared with rGO coated CNTs samples. Field emission results demonstrate that the emission current density and field enhancement factors were significantly enhanced after rGO deposition on CNTs due to the formation of sharp protrusions in rGO sheets. Local field enhancement at the apex of sharp protrusions allows tunneling and hence emission of electrons from tips at considerable lower voltage. rGO coated CNTs based field emitters on nickel foam, among all studied emitters, demonstrated the highest emission current density of 64 mA/cm2, lowest turn-on field of 0.71 and the highest field enhancement factor of 15,999. Excellent field emission characteristics of metal foam based three-dimensional field emitters suggest the potential of the synthesized cathodes in various field-emission applications.

Down syndrome (DS) is characterized by cognitive deficits throughout the lifespan and with the development of aging-dependent Alzheimer’s type neuropathology, which is related to the triplication of the amyloid β precursor protein (APP) gene. A dysfunctional endosomal system in neurons is an early characteristic of DS and APP-metabolites accumulate in endosomes in DS neurons. We have previously shown enhanced release of exosomes in the brain of DS patients and the mouse model of DS Ts[Rb(12.17(16))]2Cje (Ts2), and by DS fibroblasts, as compared to diploid controls. Here, we demonstrate that exosome-enriched extracellular vesicles (hereafter called EVs) isolated from the brain of DS patients, Ts2 mice and from the culture media of human DS fibroblasts are enriched in APP carboxyl-terminal fragments (APP-CTFs) as compared with diploid controls. Moreover, APP-CTFs levels increase in an age-dependent manner in EVs isolated from the brain of Ts2 mice. The release of APP-CTFs-enriched exosomes may have a pathogenic role by transporting APP-CTFs into naïve neurons and propagating these neurotoxic metabolites, which are also a source of amyloid β, throughout the brain, but also provides a benefit to DS neurons by shedding APP-CTFs accumulated intracellularly.

The present study attempts to understand the association of homocysteine, vitamin B12, folate, and MTHFR C677T gene polymorphism with cognitive impairment (CI) among 808 individuals of either sex (aged 30–70 years) from a largely vegetarian, mendelian population of North India. Biochemical and genetic analyses were done using standard protocols. Results indicate that 34.3% of the subjects had mild CI, 28.7% moderate CI and 0.2% were having severe CI. Hyperhomocysteinemia was found to be a significant risk factor for moderate/severe CI. Both CT genotype and T allele of MTHFR C677T gene polymorphism were found to pose significant decreased risk for CI.

Brain diffusion properties are at present most commonly evaluated by magnetic resonance (MR) diffusion imaging. MR cannot easily distinguish between the extracellular and intracellular signal components, but the older technique of real-time iontophoresis (RTI) detects exclusively extracellular diffusion. Interpretation of the MR results would therefore benefit from auxiliary RTI measurements. This requires a molecular probe detectable by both techniques. Our aim was to specify a minimum set of requirements that such a diffusion probe should fulfill and apply it to two candidate probes: the cation tetramethylammonium (TMA+), used routinely in the RTI experiments, and the anion hexafluoroantimonate ( SbF 6 − ). Desirable characteristics of a molecular diffusion probe include predictable diffusion properties, stability, minimum interaction with cellular physiology, very slow penetration into the cells, and sufficiently strong and selective MR and RTI signals. These properties were evaluated using preparations of rat neocortical slices under normal and ischemic conditions, as well as solutions and agarose gel. While both molecules can be detected by MR and RTI, neither proved an ideal candidate. TMA+ was very stable but it penetrated into the cells and accumulated there within tens of minutes. SbF 6 − did not enter the cells as readily but it was not stable, particularly in ischemic tissue and at higher temperatures. Its presence also resulted in a decreased extracellular volume. These probe properties help to interpret previously published MR data on TMA+ diffusion and might play a role in other diffusion experiments obtained with them.

The effect of intracerebroventricular administration of μ-opioid agonist, morphine (a drug of potential abuse), and its antagonist, naloxone, followed by morphine was studied on the metabolism of acetylcholine and gamma amino butyric acid in seven discrete regions of brain from EBP-primed ovariectomized rats. We also assayed serum luteinizing hormone and follicle stimulating hormone after morphine and naloxone + morphine treatments. Cholineacetyltransferase and acetylcholinesterase, gamma-aminobutyric acid transaminase, succinic semialdehyde dehydrogenase and glutamate dehydrogenase activities were found to decrease significantly in hypothalamic as well as other brain regions studied. Naloxone given prior to morphine injection was seen to reverse the effect of morphine on enzymes activities. Our study provides evidence that opioidergic modulation of GnRH release is mediated through cholinergic and GABAergic neurotransmission besides monoaminergic control and the results may further help to elucidate the basis of neuronal dysfunction in opiate addicts.

We examined the effect of intracerebroventricular (i.c.v.) administration of μ-opioid agonist, morphine, and its antagonist naloxone followed by morphine on the activities of monoamine-metabolizing enzymes, namely tyrosine hydroxylase (TH) and monoamine oxidase (MAO) along with adenosinetriphosphatase (Na + , K + -ATPase), the enzyme responsible for the maintenance of ionic gradients across the membrane, in seven discrete regions of brain from estrogen- and progesterone-primed ovariectomized rats. TH activity decreased after morphine treatment in some areas such as the median eminence-arcuate region (ME-ARC), the amygdala, and the thalamus, showing statistically significant change. MAO activity increased in all the areas studied, but more appreciable change was observed in medial preoptic area (mPOA), the ME-ARC region, and the cortex. Pronounced increase in Na + , K + -ATPase enzyme activity was observed after the drug treatment. Naloxone given prior to morphine injection resulted in recovery of the enzyme activities in most of the areas studied. Our study may provide insights into the precise opioidergic modulation of gonadotropin releasing hormone (GnRH) release mechanisms through the involvement of monoaminergic system, elucidating the basis of various neuronal dysfunctions and their management in opioid addicts.

The effect of intraventricular (IVT) administration of GABAA receptor agonist muscimol and GABAB receptor agonist, baclofen was examined on the activity of acetylcholinesterase (AChE), monoamine oxidase (MAO) and Na+, K+-ATPase in discrete areas of brain from estrogen-progesterone primed ovariectomized rats. AChE enzyme activity was increased in two subcellular fractions (soluble and total particulate) studied, with statistically significant changes in cerebral hemispheres (CH), cerebellum (CB), thalamus (TH) and hypothalamus (HT), Na+, K+-ATPase enzyme activity was decreased in both these fractions. MAO activity increased significantly in CH, TH and HT. The presented results suggest a functional relationship between GABAergic (inhibitory), cholinergic and monoaminergic (excitatory) systems by affecting the rate of degradation of the excitatory neurotransmitters and Na+, K+-ATPase. (Mol Cell Biochem 167: 107-111, 1997)

This study reports the effects of alloxan induced diabetes on glucose metabolism enzymes viz. Hexokinase, Lactate dehydrogenase, and Glucose-6-phosphate dehydrogenase from discrete brain regions. Enzymes activity was assayed from hypothalamic areas such as medial preoptic area and median eminence-arcuate region which have gonadotropin releasing hormone cell bodies and their terminals, respectively and other brain regions like septum, amygdala, hippocampus, and thalamus. In all the areas studied, induction of diabetes resulted in a significant decrease in particulate bound HK activity, whereas soluble HK, LDH and G6PDH activity showed increase at 3, 8, 15 and 28 days intervals. Insulin treatment of diabetic rats led to recovery in enzyme activity. Blood glucose levels increased significantly after induction of diabetes and recovery was seen after insulin treatment. The present results suggest that altered cerebral glucose metabolism may also be responsible for reproductive failure observed in diabetic rats. (Mol Cell Biochem141: 97–102, 1994)