On the structure of rigid semistable sheaves on algebraic surfaces

LetS be a smooth projective surface, letK be the canonical class ofS and letH be an ample divisor such thatH • K < 0. We prove that for any rigid sheafF (Ext¹ (F, F) = 0) that is Mumford-Takemoto semistable with respect toH there exists an exceptional set (E ₁ ,..., E _n ) of sheaves onS such thatF can be constructed from {E _i } by means of a finite sequence of extensions. Translated fromMatematicheskie Zametki, Vol. 64, No. 5, pp. 692–700, November, 1998. The author wishes to express his gratitude to S. A. Kuleshov for useful discussions and to A. N. Rudakov and A. L. Gorodentsev for their attention to the present work. This research was partially supported by the Russian Foundation for Basic Research under grant No. 96-01-01323 and by the INTAS Foundation.     

The newton filtration and d-determination of bifurcation problems related to C0 contact equivalence

In this paper, from the Newton filtration’s point of view, we construct the singular Riemannian metric and use the method in singular theory to study the bifurcation problems, and give the sufficient condition of d-determination of bifurcation problems with respect to C ⁰ contact equivalence. The special cases of the main result in this paper are the results of Sun Weizhi and Zou Jiancheng.     

剪切壁流有旁支管道及一小球时的流动计算

本文研究了旁支管道附近的剪切流场变化；计算时考虑到小球的存在．本文采用了《有限元程序自动生成系统》，整个计算所用工作量极少．     

An electron microscopic study of the archaeal feast/famine regulatory protein: 6. The cylindrical assembly form

Using a microcrystal of the feast/famine regulatory protein (FFRP) pot0434017 (FL11), a cryo-electron micrograph was taken, showing a projection of cylinder-like assemblies packed parallel to each other. This electron micrograph was processed in the Fourier space by selecting spots reflecting the packing and, in addition, those reflecting stacking of units inside the cylinders. Twenty seven subimages were selected, each containing three cylinders of 24 discs each, running nearly parallel to each other. By averaging these images and in combination with another average showing a different view [Ishijima, S. A., Clowney, L., and Suzuki, M. (2004) Proc. Jpn. Acad., Ser. B 80, 183–188], some details of the 3D structure of the cylindrical assembly form are discussed.     

Blood, Sweat, and Tears. Toward a Rehabilitation of the INADEQUATE Experiment

The double-quantum-filtered carbon–carbon correlation experiment (INADEQUATE) can be accelerated significantly through a reduction in the spin–lattice relaxation times by dissolving oxygen gas in the solution. The effect is enhanced by lowering the temperature and by pressurizing the sample tube with oxygen. This offers a fourfold reduction in the relaxation times of the carbon-13 resonances in the 125-MHz spectrum of methyl salicylate. The addition of perfluorotertiarybutanol (related to the artificial blood substitutes) increases the amount of oxygen that can be dissolved, so that without oxygen pressurization, similar reductions in the relaxation times can be achieved. The nuclear Overhauser enhancements are only slightly reduced by addition of oxygen. Polarization transfer from the directly attached protons (INEPT) further increases the sensitivity if at least one of the two coupled carbon sites is protonated, principally because theprotonspin–lattice relaxation times of oxygenated samples are shortened by the relaxation agent. These modest improvements in sensitivity are in general complementary to existing enhancement schemes.     

Incorporation of a lipophilic series,as coenzyme Q Homologs,din phospholipid vesicles

The incorporation of Coenzyme Q† homologs into phospholipid vesicles to achieve a concentration close to the quinone content of mitochondria has been studied with different methods. The results obtained can be summarized as follows: (a) stirring does not lead to comparable incorporation of the various CoQs tested; (b) ultrasonic irradiation results in a homogeneous incorporation both of the naturally occurring homologs of Coenzyme Q (polyisoprenoid chainlength ranging from ten to six units) and of the nonphysiological shorter chain homologs; (c) ethanol injection, which is a simple, rapid, and inexpensive technique, gives results comparable to those obtained by ultrasonication.     

Direct fluorometric analysis of a newly synthesised fluorescein-labelled marker for glomerular filtration rate

There is an obvious and growing medical need for an accurate determination of kidney function in the diagnosis and management of renal diseases. The glomerular filtration rate (GFR) is the accepted gold standard measurement of kidney function. Several approaches to estimate the GFR are available, but most of them are inconvenient and, therefore, of limited acceptance. A new method of quantification with fluorescein-isothiocyanate (FITC) sinistrin (FS), a novel GFR marker, has been evaluated. The method is based on the fluorescence label of FS and can be performed with a standard fluorometer. To control the interference of protein with the fluorescence signal, a calibration function was developed. The accuracy of the fluorometric method established is comparable to the so-called gold standard of enzymatic determination of polyfructosan. Moreover, FS is easy to handle and requires low-cost instruments. Our results demonstrate the potential of the direct fluorometric analysis of the new FITC-labelled marker of being a precise, simple, rapid and cost-effective method for diagnosing disturbed kidney function and monitoring its treatment efficacy. The dramatic decrease in analytical effort will result in a significantly higher acceptability of GFR determination.     

Preparation and characterization of modified polyphenylsulfone membranes with hydrophilic property for filtration of aqueous media

In the present research, the low water flux of polyphenylsulfone membranes was addressed, and a novel improvement in their water permeation and fouling resistance was achieved using polyethylene glycol (PEG) as the hydrophilic additive. Scanning electron microscopy and field emission scanning electron microscopy, atomic force microscopy, attenuated total reflection Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and tensile test were applied for the investigation of membrane morphology, surface topography, surface chemical structure, thermal stability, and mechanical properties, respectively. Moreover, the relative hydrophilicity/hydrophobicity of the membranes was assessed via determination of membrane water uptake capacity and water contact angle. The membrane performance was studied and compared by determination of pure water flux and filtration of canned beans production wastewater as well as bovine serum albumin solution. The filtration results indicated a remarkable pure water flux and 100% turbidity rejection provided by the polyphenylsulfone/PEG 20 000 membrane. In addition, it was confirmed that the amount of residual PEG within the membrane was increased with increasing PEG molecular weight and concentration.     

Semi‐Interpenetrating Polymer Network Biomimetic Structure Enables Superelastic and Thermostable Nanofibrous Aerogels for Cascade Filtration of PM2.5

Particulate matter (PM) has taken heavy tolls on the global economy and public health, calling for air filters that can remove PM from high‐temperature emission sources. However, creating desirable filter media capable of capturing polydisperse fine particles (PFPs) effectively and enduringly, while also withstanding high speed airstream, is extremely challenging. Here, a biomimetic and bottom‐up strategy to prepare superelastic, strong, and thermostable nanofibrous aerogels (NFAs) as cascade filters by assembling semi‐interpenetrating polymer network (semi‐IPN)‐based nanofibers into a gradient architecture is reported. Inspired by the robust loofah sponges originating from stiff cellulose networks, the mechanical property of NFAs is enhanced via tailoring the chain flexibility of heat‐resistant semi‐IPNs. Further constructing a gradient cellular architecture endows NFAs with a versatile cascade filtration behavior for capturing polydisperse fine particles. The resultant semi‐IPN‐based gradient NFAs exhibit temperature‐invariant superelasticity, a high compressive stress (7.9 kPa) and modulus (12 kPa), high filtration efficiency (>99.97%, PM_0.3), low pressure drop (≈50% that of membranes), and ultrahigh dust‐holding capacity (114 g m^?2). The fabrication of this attractive material paves the way for designing next‐generation air filters for industrial dust removal.     

Alternative sample preparation prior to two-dimensional electrophoresis protein analysis on solid lipid nanoparticles

The proteins adsorbing onto the surface of intravenously injected drug carriers are regarded as a key factor determining the organ distribution. Depending on the particle surface properties, certain proteins will be preferentially adsorbed, leading to the adherence of the particle to cells with the appropriate receptor. Therefore, the knowledge of the protein adsorption pattern and the correlation to in vivo behavior opens the perspective for the development of intravenous colloidal carriers for drug targeting. After incubation in plasma, the adsorbed proteins were analyzed using two-dimensional polyacrylamide gel electrophoresesis (2-D PAGE, 2-DE). The purpose of the present study was to develop an alternative separation method to separate solid lipid nanoparticles (SLN) carriers from plasma by gel filtration prior to 2-D PAGE. Via the specific absorption coefficients and a two-equation system, elution fractions were identified being practically plasma-free. This allows protein analysis on SLN which are typically in density too close to the density value of water to be separated by the standard centrifugation method. The SLN used for establishing the gel filtration were prepared in a way that they had a sufficiently low density to be additionally separated by centrifugation. The adsorption patterns obtained after separation with both methods were qualitatively and quantitatively identical, showing the suitability of the gel filtration.