Spectroscopy and chemical synthesis of interstellar ice analogues

Molecular synthesis and chemical evolution in the interstellar medium has been studied under laboratory conditions. The method of preparation and energetic processing of interstellar ice analogues on surfaces, spectroscopic principles for monitoring chemistry and morphology of these ice analogues and analysis methodologies are discussed in detail. The modification of a portable, ultrahigh vacuum (UHV) system for electron irradiation, vacuum ultraviolet (VUV) spectroscopy and temperature programmed desorption (TPD) of interstellar ice analogues are described in this thesis. Experimental procedures to grow interstellar ice analogues of pure molecules and mixtures are described. The results from the various experiments discussed in this thesis are classified into four main parts: VUV spectroscopy, electron irradiation of interstellar (IS) ice analogues, simultaneous irradiation and generation of IS ice analogues and temperature programmed desorption of interstellar ice analogues. Temperature dependent vacuum ultraviolet (VUV) photo-absorption spectra of pure molecular ices such as HCONH2, HCOOH, HCOOCH3, CH2CHCH2OH CH3COOCH3, CH3CH2COOH, C6H6 and O3 have been measured on the UV1 beamline of the ASTRID Synchrotron at the University of Aarhus in Denmark and UV A1 beamline at NSRRC, Taiwan. These spectra and photo-absorption cross-sections in the condensed phase are also presented. In particular, temperature dependent VUV photoabsorption characteristics of condensed ice films of O3 are measured for the first time. Electron induced molecular synthesis in pure organic ice films of HCONH2, HCOOCH3, CH3COOH, NO and binary ice mixtures of CH3OH+NO (1:1) are also reported. Newly identified pathways of molecular synthesis are discussed. Molecular synthesis during simultaneous electron irradiation and physisorption of a binary mixture of CH3OH+NH3 (1:1) is studied for the first time. Simultaneous irradiation-deposition has shown very interesting behaviour in terms of efficiency of formation of radical species such as OCN-, NH4+ etc and biologically important complex organic species such as HCONH2, HCOOCH3, CH3COOH, CH3OCH3, CH2CHCHO etc. Simultaneous irradiation deposition closely simulate the effect of cosmic ray irradiation in a dense molecular cloud and reveal new pathways of formation with higher efficiencies even at lower column densities of reactants. Finally preliminary results of a temperature programmed desorption study of pure NO ice films are also presented along with the future challenges and strategies

Dietary fat and risk of breast cancer

BACKGROUND: Breast cancer is one of the major public health problems among women worldwide. A number of epidemiological studies have been carried out to find the role of dietary fat and the risk of breast cancer. The main objective of the present communication is to summarize the evidence from various case-control and cohort studies on the consumption of fat and its subtypes and their effect on the development of breast cancer. METHODS: A Pubmed search for literature on the consumption of dietary fat and risk of breast cancer published from January 1990 through December 2003 was carried out. RESULTS: Increased consumption of total fat and saturated fat were found to be positively associated with the development of breast cancer. Even though an equivocal association was observed for the consumption of total monounsaturated fatty acids (MUFA) and the risk of breast cancer, there exists an inverse association in the case of oleic acid, the most abundant MUFA. A moderate inverse association between consumption of n-3 fatty acids and breast cancer risk and a moderate positive association between n-6 fatty acids and breast cancer risk were observed. CONCLUSION: Even though all epidemiological studies do not provide a strong positive association between the consumption of certain types of dietary fat and breast cancer risk, at least a moderate association does seem to exist and this has a number of implications in view of the fact that breast cancer is an increasing public health concern

Chronic Exposure to Pesticides- Neurological, Neurobehavioral and Molecular Targets of Neurotoxicity

Non

siRNA against presenilin 1 (PS1) down regulates amyloid β42 production in IMR-32 cells

<p>Abstract</p> <p>Background</p> <p>One of the pathological hallmarks of Alzheimer's disease (AD) is the deposition of the ~4 kDa amyloid β protein (Aβ) within lesions known as senile plaques. Aβ is also deposited in the walls of cerebral blood vessels in many cases of AD. A substantial proportion of the Aβ that accumulates in the AD brain is deposited as Amyloid, which is highly insoluble, proteinaceous material with a β-pleated-sheet conformation and deposited extracellularly in the form of 5-10 nm wide straight fibrils. As γ-secretase catalyzes the final cleavage that releases the Aβ42 or 40 from amyloid β -protein precursor (APP), therefore, it is a potential therapeutic target for the treatment of AD. γ-Secretase cleavage is performed by a high molecular weight protein complex containing presenilins (PSs), nicastrin, Aph-1 and Pen-2. Previous studies have demonstrated that the presenilins (PS1 and PS2) are critical components of a large enzyme complex that performs γ-secretase cleavage.</p> <p>Methods</p> <p>In this study we used RNA interference (RNAi) technology to examine the effects of small-interfering RNA (siRNA) against PS1 on expression levels of PS1 and Aβ42 in IMR-32 Cells using RTPCR, western blotting and immunofluorescence techniques.</p> <p>Results</p> <p>The results of the present study showed down regulation of PS1 and Aβ42 in IMR32 cells transfected with siRNA against PS1.</p> <p>Conclusion</p> <p>Our results substantiate the concept that PS1 is involved in γ-secretase activity and provides the rationale for therapeutic strategies aimed at influencing Aβ42 production.</p

Development Of Raspberry Pi-based Processing Unit for UV Photon-Counting Detectors

In ultraviolet (UV) astronomical observations, photons from the sources are very few compared to the visible or infrared (IR) wavelength ranges. Detectors operating in the UV usually employ a photon-counting mode of operation. These detectors usually have an image intensifier sensitive to UV photons and a readout mechanism that employs photon counting. The development of readouts for these detectors is resource-intensive and expensive. In this paper, we describe the development of a low-cost UV photon-counting detector processing unit that employs a Raspberry Pi with its in built readout to perform the photon-counting operation. Our system can operate in both 3x3 and 5x5 window modes at 30 frames per sec (fps), where 5x5 window mode also enables the provision of detection of double events. The system can be built quickly from readily available custom-off-the-shelf (COTS) components and is thus used in inexpensive CubeSats or small satellite missions. This low-cost solution promises to broaden access to UV observations, advancing research possibilities in space-based astronomy

Difficulties in emotion regulation scale-short form (DERS-SF): Psychometric validation and measurement invariance testing in a sample of urban Indian adolescents

Background: Adolescents are particularly vulnerable to emotion dysregulation (ED), a transdiagnostic marker of psychological disorders with implications for academic achievement, identity development, social bonding, mental health, and the overall well-being and development of adolescents. A well-validated tool for the assessment of ED is imperative for credible advances in research on ED among Indian adolescents. Difficulties in Emotion Regulation Scale-Short Form (DERS-SF) is a promising tool to assess ED but requires proper psychometric validation among Indian adolescents. The current study validated the factor structure and examined psychometric aspects including gender invariance testing of the DERS-SF in Indian adolescents aged between 14 and 20 years. Methods: In a cross-sectional study, a community sample of n = 2079 adolescents completed the English version of the DERS-SF, the Strengths, and Difficulties Questionnaire, the Barratt Impulsiveness Scale, and the Adolescent Problem Behaviour Index. Results: The six-factor model of the DERS-SF exhibited an acceptable model fit in the current study sample. Invariance testing revealed that the DERS-SF is conceptually interpreted in a similar manner by male and female adolescents. Two-way MANOVA indicated gender and age variations on a few DERS-SF subscales. Reliability for DERS-SF was good, α = 0.86. Adequate construct validity was demonstrated by moderate to strong associations of the DERS-SF subscales with measures of internalizing and externalizing symptoms, adolescent problem behaviors, and impulsivity. Conclusions: DERS-SF retained the popular six-factor structure with acceptable psychometric properties and hence can be reliably used with Indian adolescents

Electron induced chemistry: a new frontier in astrochemistry

The commissioning of the ALMA array and the next generation of space telescopes heralds the dawn of a new age of Astronomy, in which the role of chemistry in the interstellar medium and in star and planet formation may be quantified. A vital part of these studies will be to determine the molecular complexity in these seemingly hostile regions and explore how molecules are synthesised and survive. The current hypothesis is that many of these species are formed within the ice mantles on interstellar dust grains with irradiation by UV light or cosmic rays stimulating chemical reactions. However, such irradiation releases many secondary electrons which may themselves induce chemistry. In this article we discuss the potential role of such electron induced chemistry and demonstrate, through some simple experiments, the rich molecular synthesis that this may lead to

LncRNA VEAL2 regulates PRKCB2 to modulate endothelial permeability in diabetic retinopathy

Long non‐coding RNAs (lncRNAs) are emerging as key regulators of endothelial cell function. Here, we investigated the role of a novel vascular endothelial‐associated lncRNA (VEAL2) in regulating endothelial permeability. Precise editing of veal2 loci in zebrafish (veal2 (gib005Δ8/+)) induced cranial hemorrhage. In vitro and in vivo studies revealed that veal2 competes with diacylglycerol for interaction with protein kinase C beta‐b (Prkcbb) and regulates its kinase activity. Using PRKCB2 as bait, we identified functional ortholog of veal2 in humans from HUVECs and named it as VEAL2. Overexpression and knockdown of VEAL2 affected tubulogenesis and permeability in HUVECs. VEAL2 was differentially expressed in choroid tissue in eye and blood from patients with diabetic retinopathy, a disease where PRKCB2 is known to be hyperactivated. Further, VEAL2 could rescue the effects of PRKCB2‐mediated turnover of endothelial junctional proteins thus reducing hyperpermeability in hyperglycemic HUVEC model of diabetic retinopathy. Based on evidence from zebrafish and hyperglycemic HUVEC models and diabetic retinopathy patients, we report a hitherto unknown VEAL2 lncRNA‐mediated regulation of PRKCB2, for modulating junctional dynamics and maintenance of endothelial permeability