Aplikasi Ujian Online Pada Mobile Device Android

Pada saat ini perkembangan handphone yang mendukung koneksi Internet dan teknologi Android semakin berkembang pesat. Aplikasi Android telah banyak digunakan pada handphone sebagai penunjang aktifitas sehari-hari. Salah satu contoh aplikasi yang bisa dikembangkan lebih lanjut ialah ujian online yang dapat digunakan sebagai media alternatif dalam pengerjaan ujian.Pada skripsi ini dikembangkan aplikasi ujian online yang memungkinkan pengguna handphone untuk mengerjakan tes yang terdiri dari soal multiple choice dengan single maupun multi answer, dan soal essay, serta melihat hasil tes yang pernah diikutinya. Aplikasi ujian online menggunakan koneksi Internet untuk berkomunikasi dengan server. Aplikasi ujian online dibuat dengan menggunakan bahasa pemrograman Java.Berdasarkan hasil pengujian, aplikasi ini dapat berjalan dengan baik pada smartphone dengan sistem operasi Android versi 4.0 (Ice Cream Sandwich) ke atas dalam orientasi landscape

SinR is a mutational target for fine-tuning biofilm formation in laboratory-evolved strains of Bacillus subtilis

Background: Bacteria often form multicellular, organized communities known as biofilms, which protect cells from a variety of environmental stresses. During biofilm formation, bacteria secrete a species-specific matrix; in Bacillus subtilis biofilms, the matrix consists of protein polymers and exopolysaccharide. Many domesticated strains of B. subtilis have a reduced ability to form biofilms, and we conducted a two-month evolution experiment to test whether laboratory culturing provides selective pressure against biofilm formation in B. subtilis. Results: Bacteria grown in two-month-long batch culture rapidly diversified their biofilm-forming characteristics, exhibiting highly diverse colony morphologies on LB plates in the initial ten days of culture. Generally, this diversity decreased over time; however, multiple types of colony morphology remained in our final two-month-old populations, both under shaking and static conditions. Notably, while our final populations featured cells that produce less biofilm matrix than did the ancestor, cells overproducing biofilm matrix were present as well. We took a candidate-gene approach to identify mutations in the strains that overproduced matrix and found point mutations in the biofilm-regulatory gene sinR. Introducing these mutations into the ancestral strain phenocopied or partially phenocopied the evolved biofilm phenotypes. Conclusions: Our data suggest that standard laboratory culturing conditions do not rapidly select against biofilm formation. Although biofilm matrix production is often reduced in domesticated bacterial strains, we found that matrix production may still have a fitness benefit in the laboratory. We suggest that adaptive specialization of biofilm-forming species can occur through mutations that modulate biofilm formation as in B. subtilis. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0301-8) contains supplementary material, which is available to authorized users

Regularities of ultrasonography of suspensions of alumina nanoparticles in biological media

This paper studies the echo-contrast properties of an alumina nanopowder suspension using ultrasonography (US) fully corresponding in its characteristics to the techniques of medical ultrasound diagnostics of organs and tissues. The purpose of this study was to search for the possible effect of the ionic and protein composition of the biological medium on the intensity of the reflected echo signal of the contrast material based on nanoparticles. It was found that the pH of the blood promotes the maximum use of echo contrast options of alumina nanopowder suspensions. Particle size measurements in the suspension using the dynamic light scattering technique showed the stabilizing effect of blood serum and plasma on the nanopowder suspension, resulting in the attenuation of the echo signal. The data offer a basis for the development of new contrast materials based on nanoparticles for the ultrasound imaging of the heart and blood vessels. The considered mechanisms of the established phenomena make it possible to elucidate the processes of interaction of metal oxide nanoparticles with biological molecules. © 2013 Pleiades Publishing, Ltd

AGA Institute Quality Measure Development for the Diagnosis and Management of COVID-19

This document presents the official recommendations of the American Gastroenterological Association (AGA) regarding quality measures related to the diagnosis and management of the novel coronavirus, SARS-CoV-2. The current report outlines the process by which the Quality Committee (QC) evaluates guidance statements published by the AGA’s Clinical Guidelines Committee (CGC) to inform measure development. The recommendations discussed in this report relate to what remains an unprecedented event in contemporary history with unique challenges for CGC guidance-related measure development. The following recommendations were developed by the QC in consultation with the CGC. Their development was fully funded by the AGA Institute, with no additional outside funding.The AGA Institute provided funding for creation of this document

Адсорбция TX-100 и SDBS на поверхности нанопорошков Al2O3 и γ-Fe2O3 из водных растворов

Adsorption equilibriums in aqueous aluminum and iron oxides nanosuspensions stabilized by SDBS and TX-100 were investigated using UV spectrophotometry. It was established that the non-ionic surfactant TritonX-100 is not adsorbed from aqueous solution on a hydrophilic surface of both aluminum and iron oxide nanoparticles. At the same time adsorption of the anionic surfactant SDBS was observed in both oxides nanoparticles. In the investigated range of concentrations adsorption isotherms SDBS from aqueous solution on the surfaces of nanoparticles Al2O3 and γ-Fe2O3 not reach saturation. The share of the particles surface occupied by surfactant molecules were estimated based on the value of an area of molecules SDBS in the adsorption layer, which was derived from the isotherm of surface tension (0.10 nm2). The calculations showed that at the investigated concentrations SDBS Al2O3 employed approximately 30 % of surface of nanoparticles, and for γ-Fe2O3 – up to 10%.Методом УФ-спектрофотомерии были исследованы адсорбционные равновесия в водных наносуспензиях оксидов алюминия и железа, стабилизированных SDBS и TX-100. Установлено, что неионогенный ПАВ TritonX-100 не адсорбируется из водного раствора на гидрофильной поверхности наночастиц оксидов, как алюминия, так и железа. В то же время, для анионного ПАВ SDBS адсорбция наблюдалась на наночастицах обоих оксидов

Morphogenesis of the T4 tail and tail fibers

Remarkable progress has been made during the past ten years in elucidating the structure of the bacteriophage T4 tail by a combination of three-dimensional image reconstruction from electron micrographs and X-ray crystallography of the components. Partial and complete structures of nine out of twenty tail structural proteins have been determined by X-ray crystallography and have been fitted into the 3D-reconstituted structure of the "extended" tail. The 3D structure of the "contracted" tail was also determined and interpreted in terms of component proteins. Given the pseudo-atomic tail structures both before and after contraction, it is now possible to understand the gross conformational change of the baseplate in terms of the change in the relative positions of the subunit proteins. These studies have explained how the conformational change of the baseplate and contraction of the tail are related to the tail's host cell recognition and membrane penetration function. On the other hand, the baseplate assembly process has been recently reexamined in detail in a precise system involving recombinant proteins (unlike the earlier studies with phage mutants). These experiments showed that the sequential association of the subunits of the baseplate wedge is based on the induced-fit upon association of each subunit. It was also found that, upon association of gp53 (gene product 53), the penultimate subunit of the wedge, six of the wedge intermediates spontaneously associate to form a baseplate-like structure in the absence of the central hub. Structure determination of the rest of the subunits and intermediate complexes and the assembly of the hub still require further study

Effect of self-consistent electric field on characteristics of graphene p-i-n tunneling transit-time diodes

We develop a device model for p-i-n tunneling transit-time diodes based on single- and multiple graphene layer structures operating at the reverse bias voltages. The model of the graphene tunneling transit-time diode (GTUNNETT) accounts for the features of the interband tunneling generation of electrons and holes and their ballistic transport in the device i-section, as well as the effect of the self-consistent electric field associated with the charges of propagating electrons and holes. Using the developed model, we calculate the dc current-voltage characteristics and the small-signal ac frequency-dependent admittance as functions of the GTUNNETT structural parameters, in particular, the number of graphene layers and the dielectric constant of the surrounding media. It is shown that the admittance real part can be negative in a certain frequency range. As revealed, if the i-section somewhat shorter than one micrometer, this range corresponds to the terahertz frequencies. Due to the effect of the self-consistent electric field, the behavior of the GTUNNETT admittance in the range of its negativity of its real part is rather sensitive to the relation between the number of graphene layers and dielectric constant. The obtained results demonstrate that GTUNNETTs with optimized structure can be used in efficient terahertz oscillators.Comment: 8 pages, 9 figure

Crystal structure and location of gp131 in the bacteriophage phiKZ virion

Pseudomonas phage phi KZ and its two close relatives phi PA3 and 201 phi 2-1 are very large bacteriophages that form a separate branch in phage classification because their genomes are very different from the rest of GenBank sequence data. The contractile tail of phi KZ is built from at least 32 different proteins, but a definitive structural function is assigned to only one of them-the tail sheath protein. Here, we report the crystal structure of the C-terminal domain of another phiKZ tail protein, gene product 131 (gp131C). We show that gp131 is located at the periphery of the baseplate and possibly associates with fibers that emanate from the baseplate. Gp131C is a seven-bladed beta-propeller that has a shape of a skewed toroid. A small but highly conserved and negatively charged patch on the surface of gp131C might be important for substrate binding or for interaction with a different tail protein. (C) 2012 Elsevier Inc. All rights reserved