19F NMR studies on DnaB helicase

NMR (nuclear magnetic resonance) spectroscopy is an important technique used for structural characterisation of proteins under near-physiological condition. It is used for determining the structure of proteins at atomic resolution and to study protein-protein interactions. However, its major limitation is the size of protein. The limitation can be overcome by solution state fluorine NMR, a promising technique which is used for studying the structural dynamics of large proteins by selective fluorine labelling. Cellular processes such as bacterial DNA replication is carried out by large protein complexes such as DnaB helicase, DnaG primase and DNA polymerase enzyme. It is necessary to study these proteins under physiological conditions to gain insights into the process. DnaB is primary DNA helicase in the replisome and its main function is unwinding the duplex DNA. It interacts with various other proteins and performs different functions during the process. Its structural characterisation by electron microscopy has established that it adopts two different rotational symmetry states (C3 and C6) and the conformational interchange occurs in N-terminal domain only. The symmetrical states were determined under non-physiological conditions. The factors triggering the conformational change were determined under physiological conditions however; the precise conformation adopted by DnaB under these conditions is elusive. To gain insights into structure, dynamics and interactions of DnaB under physiological conditions, I have studied the DnaB helicase and partner proteins by fluorine NMR spectroscopy. In this thesis, I report my studies that employed fluorine 1D NMR to study conformational changes of hexameric DnaB helicase with mass of 315 kDa in solution under physiological conditions. Trifluoromethylphenylalanine (tfmF) was the chosen fluorine label, incorporated into DnaB site-specifically. DnaB helicase and their partner proteins from Escherichia coli and Bacillus stearothermophilus were studied to observe the significant features in both systems. tfmF labelled E.coli DnaB was expressed by cell-free protein synthesis and examination at different pH established that its N-terminus is flexible in solution under near-physiological conditions rather than adopting rigid conformation. Furthermore, the study revealed that its interaction with helicase loader induced more flexibility into N-terminus of DnaB. The complex of E.coli DnaB and its helicase loader is a 480 kDa protein complex and the presented fluorine data are first attempts to study the conformational changes in such large protein systems. Bacillus stearothermophilus DnaB helicase was studied with its primase, helicase loader and magnesium ion. TfmF was incorporated into DnaB by in vivo method. The fluorine data showed that N-terminus is flexible similar to E.coli DnaB. However, its interaction with primase induced rigidity to N-terminus and adopted C3 symmetry, which is in concurrence with previous work. Moreover, the gel filtration data showed that magnesium ion rendered the integrity of hexamers by forming unstable monomers. We report the initial studies on Bacillus stearothermophilus helicase loader, DnaI. The fluorine NMR and gel filtration data suggests that it interacts with DnaB monomer instead of hexamers. The presented data shows fluorine NMR as a useful tool in determining the structural dynamics of large protein systems in solutions and its data can supplement previous structural information

Face antimgaic labeling of double duplication for some special graphs

The main objective of the paper is to determine (a, d)− face antimagic labeling for the double duplication of all vertices by edges of ladder, tadpole and m-copies of path graphs. Also, if a graph G is (a, d)− face antimagic except for 3-sided faces then the double duplication of all vertices by edges of a graph G is also (a,d)-face antimagic.Publisher's Versio

Risk factors and mortality profile of post neonatal deaths; 1 month to 1 year, in a rural medical college hospital, South India

Background: Infant mortality is the most important indicator which reflect country growth standards and development. This study was aimed to assess the risk factors and clinical profile of post neonatal deaths, admitted in PICU, government Villupuram medical college.Methods: A retrospective analysis was done on post neonatal mortality data by pediatric department of government Villupuram medical college, Mundiyambakkam from January 2019 to December 2020, referral and LAMA patients were excluded from study. Data was analyzed using SPSS 18.0Results: Overall post neonatal mortality was 7.3%. Mortality amongst boys were 28 (41.1%) and girls were 40 (58.8%). Mortality of female babies were higher than male babies.Among the 68 post neonatal deaths, maximum number of mortalities was seen in 1-3 months (61.9%), maximum within 24 hours of hospital stay (54.4%), 37 cases (54.4%) were referred from GHPHC and private practitioners of the nearby districts, 28 babies (41.1%) had previous admissions, 22 babies had SNCU admissions and 6 babies had pediatric admissions. Three most common causes of mortality were bronchopneumonia, sepsis and acute CNS infections. Congenital malformations and heart disease along with failure to thrive are other causes of morbidity.Conclusions: Analysis reflects the disease occurrence, treatment modalities and quality of treatment available. Treatment at primary level can prevent postnatal deaths from infections. The preventive and primary health care system should be strengthened. All special newborn care units (SNCU) discharged babies should have both community and district early intervention centre (DEIC) follow up, immunization practices, explaining danger signs to the parents, improving the quality of life has got great impact on the post neonatal outcome

Principles of Chromatography Method Development

This chapter aims to explain the key parameters of analytical method development using the chromatography techniques which are used for the identification, separation, purification, and quantitative estimation of complex mixtures of organic compounds. Mainly, the versatile techniques of ultra−/high-performance liquid chromatography (UPLC/HPLC) are in use for the analysis of assay and organic impurities/related substances/degradation products of a drug substance or drug product or intermediate or raw material of pharmaceuticals. A suitable analytical method is developed only after evaluating the major and critical separation parameters of chromatography (examples for UPLC/HPLC are selection of diluent, wavelength, detector, stationary phase, column temperature, flow rate, solvent system, elution mode, and injection volume, etc.). The analytical method development is a process of proving the developed analytical method is suitable for its intended use for the quantitative estimation of the targeted analyte present in pharmaceutical drugs. And it mostly plays a vital role in the development and manufacture of pharmaceuticals drugs

Fuzzy zero divisor graph in a commutative ring

Let R be a commutative ring and let Γ(Zn) be the zero divisor graph of a commutative ring R, whose vertices are non-zero zero divisors of Zn, and such that the two vertices u, v are adjacent if n divides uv. In this paper, we introduce the concept of fuzzy zero zivisor graph in a commutative ring and also discuss the some special cases of Γf (Z2p), Γf (Z3p), Γf (Z5p), Γf (Z7p) and Γf (Zpq). Throughout this paper we denote the Fuzzy Zero Divisor Graph(FZDG) by Γf (Zn).Publisher's Versio

A review on conventional and laser assisted machining of Aluminium based metal matrix composites

Aluminum based Metal Matrix Composites (Al-MMC) have been found in different industrial applications due its excellent properties compared to conventional materials. Machining of these composites is difficult due to the hard particle reinforcements. The wider usage of these composites is limited due high machining cost and excessive tool wear with conventional machining. Because of increasing demands in industries, any improvement of conventional machining process or any other deployment of additional technique is directly related to higher productivity. Laser Assisted Machining has become an effective alternative to the conventional machining of these difficult- to- cut materials. This paper provides an overview of conventional machining of MMCs and the potential of LAM. An attempt is made to give a better understanding of the operating conditions such as machining parameters and Laser parameters. Finally, the summary of the review is discussed and the scope for future research is presented

Prevalence of pre-diabetes in adolescents aged 11-17 years with high risk factors

Background: Obesity is a rising global epidemic in children which leads to pre-diabetes and overt diabetes. Identification at early stage helps in early intervention. This study was undertaken to study the prevalence of pre-diabetes in urban school going adolescents aged 11-17 years with high risk factors.Methods: This was a prospective cross-sectional study conducted in Chennai, India between December 2011 and November 2012. Overweight or obese adolescents in the age group 11-17 years, either with family history of diabetes or acanthosis nigricans or both were included. After obtaining informed consent from parents, history was obtained in pre-tested questionnaire.Results: 148 adolescents were enrolled in the study (n=148), 71.62% were females, mean weight was 59.54±10.44 kg, mean height was 150.92±8.62 cm, mean BMI was 26.19±3.23 and mean blood glucose was 82.1 mg/dl. 60.81% of subjects were overweight and others obese. Girls had statistically significant higher mean weight and mean BMI than boys. 78.37% had acanthosis nigricans, 47.29% had family history of diabetes, 12.16% had pre-diabetes and the mean blood glucose in pre-diabetics was 104.9 mg/dl. Pre-diabetes was higher in adolescents with family history of diabetes (p=0.038).Conclusions: Recognition of risk of type 2 diabetes in the asymptomatic pre-diabetes phase needs to be emphasized and targeted screening of high risk children for pre-diabetes seems to be justified. The morbidity and mortality of youth onset type 2 diabetes can be reduced only by early detection and treatment

Frequency response analysis of a current limiting reactor.

Masters Degree. University of KwaZulu-Natal, Durban.With the demand for electricity continuously increasing, power systems are required to increase capacity to meet such demands which can entail integrating renewable energy resources to the grid. This increase in capacity would mean a likewise increase in fault levels in the network which can result in costly damage to components such as circuit breakers, transformers and cables. Air-core reactors are commonly employed to prevent such damages from occurring, however, the increase in fault levels must also be accounted for in the design of reactors as they are also subject to transients. This dissertation documents the development of models to accurately represent an Air-core reactor in order to gain a better understanding of the design considerations required. Two models are developed for two desktop reactors using different methods as a form of cross-validation. The first model is developed in MATLAB r2020a and utilises an analytical approach through an equivalent circuit method (ECM). Equations are used to compute the inductive, capacitive and resistive components which are then used to guide the development of the FEM models. The second model is developed using COMSOL Multiphysics software which is based on the Finite Element Method (FEM) approach. A 2D-axisymmetrical model is constructed and simulated using COMSOL’s Magnetic and Electric field physics in the frequency domain from which a frequency response is obtained as well as values for the inductive, resistive and capacitive components. Final validation of the FEM models is done through comparisons to measured results of the two desktop reactors. FEM simulated RLC components showed fairly good agreement to the measured values, particularly the inductance having a difference of 3.4 μH and a capacitance difference of 1 pF for Reactor 1. The FEM simulated frequency response of 1.5 MHz differed by 0.4 MHz when compared to the measured frequency response for Reactor 2 of 1.9 MHz. A sensitivity analysis is conducted for the FEM model in order to obtain an understanding of the design considerations required for the air-core reactor. Simulations are performed on the FEM model with changes to geometry, permittivity of the insulation medium and resistivity of the copper coil. The effects of these changes on the RLC parameters and resonance frequencies are documented. The FEM model is then scaled to a full-scaled reactor which showed good agreement between the expected inductance of 2.24 mH and the simulated inductance of 2.28 MH. The resultant resonant frequency was observed to occur at 380 kHz. The aim of this is to develop an understanding of parameters and equations that should be considered in the design process of reactors which will then be employed in the development of a superconducting fault current limiter (SFCL)

BACKWARD MOTION PLANNING AND CONTROL OF MULTIPLE MOBILE ROBOTS MOVING IN TIGHTLY COUPLED FORMATIONS

This work addresses the development of a distributed switching control strategy to drive the group of mobile robots in both backward and forward motion in a tightly coupled geometric pattern, as a solution for the deadlock situation that arises while navigating the unknown environment. A generalized closed-loop tracking controller considering the leader referenced model is used for the robots to remain in the formation while navigating the environment. A tracking controller using the simple geometric approach and the Instantaneous Centre of Radius (ICR), to drive the robot in the backward motion during deadlock situation is developed and presented. State-Based Modelling is used to model the behaviors/motion states of the proposed approach in MATLAB/STATEFLOW environment. Simulation studies are carried out to test the performance and error dynamics of the proposed approach combining the formation, navigation, and backward motion of the robots in all geometric patterns of formation, and the results are discussed

Pengaruh Efikasi Kendiri Dan Kolektif Guru Terhadap Hubungan Antara Kepimpinan Transformasi Sekolah Dengan Komitmen Kualiti Pengajaran

Kajian ini bertujuan untuk mengkaji pengaruh efikasi kendiri dan efikasi kolektif guru terhadap hubungan antara kepimpinan transformasi sekolah dengan komitmen kualiti pengajaran. Secara khususnya kajian ini menghuraikan (1) pengaruh kepimpinan transformasi sekolah terhadap komitmen pengajaran dan pembelajaran guru, komitmen inovasi pengajaran serta efikasi kolektif guru, (2) pengaruh efikasi kendiri sebagai moderator terhadap hubungan antara kepimpinan transformasi sekolah dengan efikasi kolektif guru dan (3) pengaruh efikasi kolektif guru sebagai mediator terhadap hubungan antara kepimpinan transformasi sekolah dengan komitmen kualiti pengajaran