Xains Info: September 2008

SANS and DLS Studies of Protein Unfolding in Presence of Urea and Surfactant

Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) have been used to studyconformational changes in protein bovine serum albumin (BSA) during its unfolding in presence of protein denaturatingagents urea and surfactant. On addition of urea, the BSA protein unfolds for urea concentrations greater than 4 M andacquires a random coil configuration with its radius of gyration increasing with urea concentration. The addition ofsurfactant unfolds the protein by the formation of micelle-like aggregates of surfactants along the unfolded polypeptidechains of the protein. The fractal dimension of such a protein-surfactant complex decreases and the overall size of thecomplex increases on increasing the surfactant concentration. The conformation of the unfolded protein in the complexhas been determined directly using contrast variation SANS measurements by contrast matching the surfactant to themedium. Results of DLS measurements are found to be in good agreement with those obtained using SANS.Keywords: Protein unfolding, small-angle neutron scattering, dynamic light scattering. V. K. Aswal\ s. N. Chodankar\ J. Kohlbrecher2, R. Vavrin2 and A. G. Wagh11 Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India2Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

KOMUNIKASI dalam ORGANISASI

Manusia di dalam kehidupannya harus berkomunikasi, artinya memerlukan orang lain dan membutuhkan kelompok atau masyarakat untuk saling berinteraksi. Hal ini merupakan suatu hakekat bahwa sebagian besar pribadi manusia terbentuk dari hasil integrasi sosial dengan sesama dalam kelompok dan masyarakat. Di dalam kelompok/organisasi itu selalu terdapat bentuk kepemimpinan yang merupakan masalah penting untuk kelangsungan hidup kelompok, yang terdiri dari pemimpin dan bawahan/karyawan. Di antara kedua belah pihak harus ada two-way-communications atau komunikasi dua arah atau komunikasi timbal balik, untuk itu diperlukan adanya kerja sama yang diharapkan untuk mencapai cita-cita, baik cita-cita pribadi, maupun kelompok, untuk mencapai tujuan suatu organisasi. Kerja sama tersebut terdiri dari berbagai maksud yang meliputi hubungan sosial/kebudayaan. Hubungan yang terjadi merupakan suatu proses adanya suatu keinginan masing-masing individu, untuk memperoleh suatu hasil yang nyata dan dapat memberikan manfaat untuk kehidupan yang berkelanjutan. Hubungan yang dilakukan oleh unsur pimpinan antara lain kelangsungan hidup berorganisasi untuk mencapai perkembangan ke arah yang lebih baik dengan menciptakan hubungan kerja sama dengan bawahannya. Hubungan yang dilakukan oleh bawahan sudah tentu mengandung maksud untuk mendapatkan simpati dari pimpinan yang merupakan motivasi untuk meningkatkan prestasi kerja ke arah yang lebih baik. Hal ini tergantung dari kebutuhan dan cara masing-masing individu, karena satu sama lain erat hubungannya dengan keahlian dan tugas-tugas yang harus dilaksanakan. Bila sasaran komunikasi dapat diterapkan dalam suatu organisasi baik organisasi pemerintah, organisasi kemasyarakatan, maupun organisasi perusahaan, maka sasaran yang dituju pun akan beraneka ragam, tapi tujuan utamanya tentulah untuk mempersatukan individu-individu yang tergabung dalam organisasi tersebut. Berdasarkan sifat komunikasi dan jumlah komunikasi menurut Onong Uchyana Effendi, dalam bukunya “Dimensi-Dimensi Komunikasi” hal. 50, komunikasi dapat digolongkan ke dalam tiga kategori: 1. Komunikasi antar pribadi Komunikasi ini penerapannya antara pribadi/individu dalam usaha menyampaikan informasi yang dimaksudkan untuk mencapai kesamaan pengertian, sehingga dengan demikian dapat tercapai keinginan bersama. 2. Komunikasi kelompok Pada prinsipnya dalam melakukan suatu komunikasi yang ditekankan adalah faktor kelompok, sehingga komunikasi menjadi lebih luas. Dalam usaha menyampaikan informasi, komunikasi dalam kelompok tidak seperti komunikasi antar pribadi. 3. Komunikasi massa Komunikasi massa dilakukan dengan melalui alat, yaitu media massa yang meliputi cetak dan elektronik.

Structure and Morphology of Neodymium-doped Cerium........

Oxide Solid Solution Prepared by a Combined SimplePolymer Heating and D.C.-Magnetron Sputtering Method. Neodymium-doped Cerium Oxide (NDC) solid solution is attractive alternative material to replace yttria-stabillizedzirconia (YSZ) used as an electrolyte for solid-oxide fuel cells (SOFCs). In this study Nd-Ce02 nanoparticIeswith Nd of 3, 6 and 9 at.!at.-% were synthesized by simple polymer heating. The NDC thin films were deposited onsilicon substrates by using target made from the nanoparticIes. Deposition process was carried out by D.C.-magnetronsputtering at temperature as low as 375°C. XRD pattern was used to confirm solid solubility and structural properties ofthe films. The results indicated that all samples are single phase solid solution with cubic fluorite structure. Their latticeparameters increase with increasing Nd content. It was also found that the mean grain size decrease with increasing Ndcontent. SEM analysis showed that NDC thin films have dense and uniform thickness. These results revealed that thenanoparticIes and thin films of NDC solid solution are successfully prepared by a combined simple polymer heating andD.C.-Magnetron Sputtering method at low temperature.Keywords: Cerium oxide, D.C. magnetron sputtering, nanoparticIes, polymer heating. I. Nurhasanahl, M. Abdullah2, and Khairurrijae1Department of Physics, Faculty of Mathematics and Natural Sciences,Diponegoro University, Semarang, 50275, Indonesia2 Physics of Electronics Materials Research Division, Faculty of Mathematics and Natural Sciences,Institut Teknologi Bandung, Bandung 40132, Indonesia.

Zircon Supported Copper Catalysts for the Steam Reforming of Methanol

Steam reforming of methanol (SRM) is known as one of the most favorable catalytic processes for producinghydrogen. Current research on zirconia, Zro2 supported copper catalyst revealed that CuO/zr02 as an active catalyst forthe SRM. Zircon, ZrSi04 is available from the by-product of tin mining. In the work presented here, the catalyticproperties of CuO/ZrSi04 with various copper oxide compositions ranging from 2.70% (catalyst I), 4.12% (catalyst II),and 7.12 %-mass (catalyst III), synthesized by an incipient wetness impregnation technique, were investigated tomethanol conversion, selectivity towards CO formation, and effect of ZnO addition (7.83%CuO/8.01%ZnO/ZrSi04 =catalyst V). The catalytic activity was obtained using a fixed bed reactor and the zircon supported catalyst activity wascompared to those of CuO/ZnO/AI203 catalyst (catalyst IV) and commercial Kujang LTSC catalyst. An X-ray powderdiffraction (XRD) analysis was done to identify the abundant phases of the catalysts. The catalysts topography andparticle diameter were measured with scanning electron microscopy (SEM) and composition of the catalysts wasmeasured by SEM-EDX, scanning electron microscope-energy dispersive using X-ray analysis. The results of thisresearch provide information on the possibility of using zircon (ZrSi04) as solid support for SRM catalysts.Keywords: Steam reforming of methanol; incipient wetness impregnation technique; CuO/ZrSi04; CO formation. M. Widiastri, Fendy, and I N. MarsihInorganic and Physical Chemistry Group, Faculty of Mathematics and Natural Sciences,Institut Teknologi Bandung, fl. Ganesha 10 Bandung 40132, Indonesia

Physical Identification of Binary System of Gliclazide-Hydrophilic Polymers Using X-Ray Diffraction

The formation of binary system in pharmaceutical solid state is aimed to improve the physicochemicalcharacteristics of active compound, such as its solubility. To identify the physical change of the binary system includingcrystallinity or particle morphology, there are many methods can be applied. In present report, we study the physicalinteraction of the binary system of gliclazide and hydrophilic polymers. In this binary system, gliclazide was eitherdispersed or mixed with polyvinyl pirrolidone (PVP K30) or polyethylene glycol (PEG 6000). The dispersion system ofgliclazide in the polymeric carriers was prepared by solvation-evaporation method, using dichloromethane/methylenechloride as an organic solvent. The physical characterization of both dispersed and mixed of gliclazide was studied usingX-ray diffraction at interval 6-50°/28. As a comparison, the same procedure was performed for pure gliclazide. Toconfirm the diffractogram of this binary system, Fourier Transform Infrared (FT-IR) spectroscopy was carried out aswell. Both diffarctogram and FT-IR spectra revealed that there was no new compound formed in the solid dispersionsystem of gliclazide:PEG 6000 and gliclazide:PVP K30. In contrast, the solubility as well as the dissolution rate ofgliclazide in the presence of both hydrophilic polymers was increased as compared to pure gliclazide. We concludetherefore that solvatation followed by evaporation of gliclazide in the presence of either PEG 6000 or PVP K30 did notalter its crystalline characteristic. The improved of gliclazide solubility in the binary system might due to othermechanism such as increased in the wettability and the hydrophylicity effect of the polymers.Keywords: Solid dispersion, gliclazide, binary system, X-ray diffractometry, FT-IR spectroscopy, solubility, dissolution. H. Rachmawati, Yatinasari, Faizatun, S. A. SyarieResearch Group of Pharmaceutics, Institut Teknologi Bandung, Bandung 40/32 Indonesia

Synthesis and Characterization of In-situ Copper-Niobium Carbide Com posite

In this work, synthesis of copper matrix composite powder reinforced by in situ niobium carbide particle wasprepared by mechanical alloying of elemental powder and subsequent heat treatment. Elemental powders of Cu-Nb-Ccorrespond to Cu-40wt%Nb-1O%wtC composition was milled for 54 hours at room temperature in a planetary ball mill.The effect of heat treatment temperature on the formation of niobium carbide was analyzed. Characterization by X-raydiffraction was done on the milled powder and heat-treated powder in order to investigate NbC formation. Resultsindicate that NbC began to precipitate after mechanical alloying for about 54h with heat treatment temperature of 900°Cand lOOO°C.Keywords: X-ray diffraction, in situ composite, mechanical alloying, copper matrix composite. H. Zuhailawati R.Othmanl, D.L. Buil, M. Umemoto2I School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia,14300 Nibong Tebal, Penang, Malaysia2Department of Production Systems Engineering, Toyohashi University of Technology, Japan

Deuterium Labeling and Neutron Scattering for Structural Biology

Neutron scattering applications in structural biology are strongly enhanced by deuterium labeling either of theaqueous solvent or of the macromolecules themselves, or both. In protein crystallography deuteration of the solvent andprotein allows a clear visualization of hydrogen sites (deuterium atoms) as well as increasing signal/noise in thediffraction data. This allows crystals as small as 0.lmm3 to be used. In small angle scattering and reflectometrydeuteration of the aqueous solvent allows one to exploit manipulate the contrast between different componentscomplexes such as proteins, nucleic acids or lipids. In the case of multi-protein complexes the in vivo deuteration ofindividual protein sub-units allows an even more sophisticated contrast variation to be performed.Keywords: Structural biology, neutron scattering, deuterium labeling, contrast variation. Peter Timminslnstitut Laue-Langevin, BP 156, 6 rue Jules Horowitz38042 Grenoble Cedex 9, France

Polyblends ofPoly(vinyl alcohol) and POIY(E-caprolactone) and Their Properties

The increasing volume of plastic has caused the serious problem in environment. One way to solve thisproblem is preparation of new plastic materials which can be decomposed by microorganisms in environment. Theseplastics may be prepared from non-biodegradable material by modification of theirs physical and chemical properties,preparation of theirs copolymers and polyblends. The main problem in preparation of polyblends is compatibilitybetween polymers mixtures. In this work has focused on preparation of polyblends between poly(vinyl alcohol) (PYA)and poly(e-caprolactone) (PCL) in various compositions by casting of polymers solution. Characterizations ofpolyblends were carried out by analysis of functional groups (FTIR), thermal property (DSC and TGAlDTA),mechanical properties (Tensile tester), and crystallinity (XRD). The results of polyblends showed that the compatibleand homogeneous polyblends were obtained in solvent composition (dimethyl sulfoxide / tetrahydrofurane)(DMSOffHF) of 3:I and PCL ratio in polyblends less than 15 % (w/w). The absorption intensity of carbonyl and alkylgroups observed in 1725 cm-l and 2940 cm-1 increased with increasing PCL composition in polyblends. The meltingpoint (Tm) and fusion enthalpy (MIm) for PCL region in polyblends decreased with decreasing PCL composition, butmelting point (Tm) and fusion of enthalpy (MIm) for PYA region increased. The total fusion enthalpy value obtained byobservation was smaller than that of calculation value, indicating the presence of interaction between PCL and PYA toform a part of compatible polyblends with more amorphous structure. The mechanical properties of polyblends tended todecrease with increasing PCL ratio in polyblends. These results were supported by analysis of crystallinity with using X-raydiffraction.Keywords: Poly(vinyl alcohol), poly(e-caproplactone), polyblends, and compatibility. I M. Arcana and L. AliaInorganic and Physical Chemistry Research Groups, Faculty of Mathematic and Natural Sciences,Institut Teknologi Bandung, Indonesia

Preparation of Self-assembly Mesoporous Ti02 Using Block Copolymer Pluronic PE6200 Template

In this research, nanocrystal mesoporous TiOz powders were synthesized by sol-gel method, with TiCl4 as aprecursor in methanol solution. Block copolymer Pluronic PE 6200 was used as pores template. It was found that fromthe XRD measurements, both at 400°C and 450°C calcination temperatures, resulted in nanocrystal TiOz with anatasephase. Based on Nz adsorption characterization (BET method), TiOz samples have surface area 108 mZ/g and 88 mZ/g for400°C and 450°C calcination temperatures respectively. From Small-angle Neutron Scattering (SANS) patterns, it isinvestigated that TiOz samples have mesoporous structure where the pore order degree depend on the calcinationtemperature.Keywords: Titanium dioxide, mesoporous material, sol-gel method, self-assembly, block copolymer, SANS. W. Septina, B. Yuliarto, and NugrahaMaterial Processing Laboratory, Engineering Physics Department, Institut Teknologi Bandung,

The Synthesis and Characterization of Titania Nanotubes Formed at Various Anodisation Time

One-dimensional (10) nanostructured titania such as nanowires, nanorod and nanotubes have attractedconsiderable attention recently due to their unique physical properties and their potential application in waterphotoelectrolysis, photocatalysis, gas sensing, and photovoltaic. In this work, a simple anodisation method has beendeveloped to fabricate titania nanotubes in 1M Na2S04 containing various amount of NH4F. The dimension of the titaniananotube produced depend on tlle electrochemical process parameter: composition of the electrolyte, pH of theelectrolyte and time of anodisation. As for this paper, the effect of fluoride content and anodisation time on theformation of titania nanotube was discussed in detaiL The nanotubes formed were analyzed by field emission scanningelectron microscope (FESEM) and X-Ray diffraction (XRO). The minimum fluoride content that is required to formnice well ordered nanotube for sample anodized for 30 minutes is O.3g whereas for 120 minutes is O.lg.Keywords: titania nanotube, fluoride, anodizationPACS: 61.46.Fg. S. Sreekantan, L. M. Hung, Z. Lockman, Z. A. Ahmad and A. F. Mohd NoorSchool of Materials & Mineral Resource Engineering, Universiti Sains Malaysia14300, Nibong Tebal, Seberang Perai Selatan, Malaysia

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