Spin-gap behaviour in the 2-leg spin-ladder BiCu2PO6

We present magnetic suscceptibility and heat capacity data on a new S=1/2 two-leg spin ladder compound BiCu2PO6. From our susceptibility analysis, we find that the leg coupling J1/k_B is ~ 80 K and the ratio of the rung to leg coupling J2/J1 ~ 0.9. We present the magnetic contribution to the heat capacity of a two-leg ladder. The spin-gap Delta/k_B =3 4 K obtained from the heat capacity agrees very well with that obtained from the magnetic susceptibility. Significant inter-ladder coupling is suggested from the susceptibility analysis. The hopping integrals determined using Nth order muffin tin orbital (NMTO) based downfolding method lead to ratios of various exchange couplings in agreement with our experimental data. Based on our band structure analysis, we find the inter-ladder coupling in the bc-plane J2 to be about 0.75J1 placing the compound presumably close to the quantum critical limit.Comment: 8 pages, 5 figure

Virus shapes and buckling transitions in spherical shells

We show that the icosahedral packings of protein capsomeres proposed by Caspar and Klug for spherical viruses become unstable to faceting for sufficiently large virus size, in analogy with the buckling instability of disclinations in two-dimensional crystals. Our model, based on the nonlinear physics of thin elastic shells, produces excellent one parameter fits in real space to the full three-dimensional shape of large spherical viruses. The faceted shape depends only on the dimensionless Foppl-von Karman number \gamma=YR^2/\kappa, where Y is the two-dimensional Young's modulus of the protein shell, \kappa is its bending rigidity and R is the mean virus radius. The shape can be parameterized more quantitatively in terms of a spherical harmonic expansion. We also investigate elastic shell theory for extremely large \gamma, 10^3 < \gamma < 10^8, and find results applicable to icosahedral shapes of large vesicles studied with freeze fracture and electron microscopy.Comment: 11 pages, 12 figure

Fundamentals and Literature Review of Discrete Fourier Transform in Digital Signal Processing

Today’s world is digital world. While designing and analyzing the digital phenomena the most desired factor are high performance, time and cost(economy).DFT and FFT are the most efficient mathematical technique to meet these challenges .To compute DFT using FFT is genius method ,in this method FFT decomposes DFT with N sample points, into N DFT each with single point. This paper focus on DFT, FFT and its approach to Digital signal processing

Structural transformations in protein crystals caused by controlled dehydration

Recent experiments in this laboratory on structural transformations caused by controlled dehydration of protein crystals have been reviewed. X-ray diffraction patterns of the following crystals have been examined under varying conditions of environmental humidity in the relative humidity range of 100-75%: a new crystal form of bovine pancreatic ribonuclease A grown from acetone solution in tris buffer (I), the well-known monoclinic form of the protein grown from aqueous ethanol (II), the same form grown from a solution of 2-methyl pentan-2,4-diol in phosphate buffer (III), tetragonal (IV), orthorhombic (V), monoclinic (VI) and triclinic (VII) hen egg white lysozyme, porcine 2 Zn insulin (VIII), porcine 4 Zn insulin (IX) and the crystals of concanavalin A(X). I, II, IV, V and VI undergo one or more transformations as evidenced by discontinuous changes in the unit cell dimensions, the diffraction pattern and the solvent content. Such water-mediated transformations do not appear to occur in the remaining crystals in the relative humidity range explored. The relative humidity at which the transformation occurs is reduced when 2-methyl pentan-2,4-diol is present in the mother liquor. The transformations are affected by the crystal structure but not by the amount of solvent in the crystals. The X-ray investigations reviewed here and other related investigations emphasize the probable importance of water-mediated transformations in exploring hydration of proteins and conformational transitions in them

Best practices for selection of excipients for paediatrics - Workshop reflection

The development of age appropriate formulations for the paediatric population has become one of the key areas of focus for the pharmaceutical industry - with a subsequent influence on excipient use. Selection of excipients with appropriate safety and tolerability is a major hurdle in paediatric formulation development. Various factors influence selection of excipients, including target age group, route of administration and dosage form. Evaluation of these factors and a clear rationale and justification is expected by the regulators when it comes to selecting excipients for paediatric formulation. Scientists are encouraged to apply the principle of benefit to risk balance to assess the suitability of excipients to the specific paediatric population for whom the formulation is intended. In order to understand how scientists approach the task of establishing the risk to benefit analysis, a workshop was organised by the European Paediatric Formulation Initiative (EuPFI) to reflect on the current scenario and the different practices employed by formulation scientists in the selection of excipients for paediatric formulations. Aspects assessed by regulators were also canvassed. Finally, the participants were asked to comment on how selecting excipients for use in paediatric formulations may differ from the considerations applied in selecting excipients for formulations for other age groups. Based on the workshop discussion, some recommendations and questions to consider emerged regarding the selection of excipients in paediatric drug development. These best practice recommendations provided a good starting point for a more systematic strategy for selecting excipients for paediatric formulation development

Mathematical Operations on Basic Discrete Time Signals with MATLAB Programming

This paper deals with the simulation of some of the discrete time signals using MATLAB and discusses some of their mathematical operations and properties. Basic discrete time signals with MATLAB simulation is discussed in introduction along with the time domainand frequency domain analysis of discrete time signals.The frequency domain analysis is discussed with help of two important transform technique i.e. Z-transform and Discrete Fourier transform. It is thus important to learn first how to generate signals in time domain and perform basic operations on them, which are the main objectives of this paper. A secondary objective is to learn the application of some basic MATLAB commands and its usagein solving simple digital signal processing (DSP) problems

Survey on a Rule Based System to Refine User Walls

The core problem in today’s Online Social Networks (OSNs) is to allocate users the authority to manage the messages posted on their private space to avert that unwanted content. The unwanted data may contain political, vulgar, non-neural etc. message filtering systems are designed for unstructured or semi-structured data, as opposed to database applications, which use very structured data. In this paper, we proposed a System with the flexible rules to filter the unwanted messages posted on user wall. After passing threshold value, the informing message is sent to that user. This allows users to customize the refining criteria to be applied to their walls, and a Machine Learning-based classifier automatically classifies the messages and labelling messages in support of content-based filtering

Can One Teach Old Drugs New Tricks? Reformulating to Repurpose Chloroquine and Hydroxychloroquine

The outbreak of the novel corona virus disease, COVID-19, has presented health care professionals with the unique challenges of trying to select appropriate pharmacological treatments with little time available for drug testing. Given the development times and manufacturing requirements for new products, Value Added Medicines (repurposing – reformulation of existing drugs) could be one possibility to beat the COVID-19 outbreak. This review explores reformulation alternatives which could be progressed with chloroquine and hydroxychloroquine; two antimalarial drugs, that are being tested on a global scale as a potential therapeutic option. The key areas for improvement have been reviewed and the potential solutions to the problems and limitations of current formulations are discussed. The pharmaceutical challenges discussed are those of highly soluble drugs, needed to be given at high doses and presenting a real bitter taste challenge with significant gastrointestinal side effects that could be translated and repurposed into fit for purpose reformulations

Biosynthesis of copper carbonate nanoparticles by ureolytic fungi

In this research, the ureolytic fungi Neurospora crassa, Pestalotiopsis sp. and Myrothecium gramineum were investigated for the preparation of nanoscale copper carbonate and the role of fungal extracellular protein in such mineral formation. After incubation in urea-modified media, carbonate-laden fungal supernatants were used for the precipitation of copper carbonate, with experimental results agreeing closely with those obtained using geochemical modelling (Geochemist's Workbench). Compared with commercial and chemically synthesized copper carbonate, the minerals obtained using fungal supernatants were nanoscale and showed varying morphologies. It was found that extracellular protein played an important role in determining the size and morphology of the carbonate minerals precipitated, and after mixture with CuCl2 and resultant copper carbonate precipitation, more than 80% protein was removed from the N. crassa supernatant. Moreover, with addition of extracellular protein extracted from different fungal supernatants or standard bovine serum albumin, more than 96% of protein was removed by carbonate mineral precipitation. These results provide direct experimental evidence for the preparation of copper carbonate nanoparticles utilizing fungal ureolytic activity and show that fungal extracellular protein plays an important role in the formation and size of specific nano metal carbonates. Such a process provides opportunities for production of specific and/or novel metal carbonate nanoparticles of applied relevance, and as precursors of other useful biomineral products such as oxides.</p