Motifs involved in interchain binding at the tail-end of spectrin

Segments 20-22 of alpha-spectrin and 1-3 of beta-spectrin are required for high avidity interchain binding at the tail-end of the molecule. Here, sequence analysis guided by the crystal structure of spectrin's repeating segments was used to redefine the boundaries of a repetitive beta segment that is critical for interchain binding and demonstrate the contribution of non-repetitive spectrin segments in high avidity interchain binding. Our results show that several motifs together are required for high avidity binding, indicating that interchain binding at the tail-end of the spectrin molecule depends on the long distance coordination of several different elements. We also explored the role of unusual motifs contained in beta segments involved in interchain binding. A row of basic residues and a row of small hydrophobic residues were found not to be required for interchain binding, suggesting that their conservation among species reflects functions unrelated to interchain binding. The octamer between segments beta 2 and beta 3 that maintains a specific register between true binding sites was found to have an indirect role in interchain binding by stabilizing neighboring segments. A 5-residue domain in segment beta 2 (EKPPK) was required for interchain binding because it sustains normal helix-helix interactions within segments beta 2.     

Process optimization of sweet potato pulp‐based biodegradable plastics using response surface methodology

Biodegradable plastics were produced from sweet potato pulp (SPP) and cationic starch (CS) or chitosan composite (CC) by compression molding and their mechanical properties were tested. A universal testing machine, Rockwell hardness tester, and Izod impact tester were used for testing the mechanical properties (flexural strength, Rockwell hardness, and Izod strength) of the plastics. A central composite second‐order design was used to study the effects of temperature, time, and moisture content on the flexural strength, Rockwell hardness, and Izod strength of SPP/CS and SPP/CC blended plastics. The flexural strength, Rockwell hardness, and Izod strength of SPP‐based plastics was 101.1–305.9 kg/cm², R29.0–R96.7, and 0.6–3.0 kg cm cm^?2, respectively. Regression analysis predicted the optimal mechanical properties (flexural strength, Rockwell hardness, and Izod strength) to be attained with a 150–160°C temperature, 15–20‐min reaction time, and 20–23% moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 423–434, 2002     

纤维增强塑料筋的性能与发展

本文详细介绍了纤维增强塑料筋（Fiber Reinforced Plastic Rebar，简称FRP筋）在国内外的发展概况及其基本物理力学性能，指出了目前的纤维增强塑料筋及其混凝土构件力学性能研究中存在的问题。     

Direct Observation of Triplet Reactions of Anthraquinone Vat Dyes Using Nanosecond Laser Photolysis

The triplet-triplet spectra of three commercial anthraquinone vat dyes (C.I. 67300, C.I. 59100 and C.I. 60515) were studied in solution at room temperature using laser photolysis. The triplet states of these dyes react with oxygen, and the rate constants for the quenching process were measured, together with the rates of energy transfer from the triplet state to anthracene. These observations are considered in relation to the photoreactivity of these dyes.     

Aldol condensation of butanal over alkali metal zeolites

Alkali metal zeolites and metal oxides were used for the aldol condensation of n-butanal to 2-ethyl-2-hexenal. The order of activity at 150 °C and 1 atm. was: CsNaY > NaY > LiNaY > MgO >Al₂O₃. Selectivity to 2-ethyl-2-hexenal was 100% for both pure and mixed isomer feed. Infrared spectroscopic studies showed that stable catalysts were produced by propene pretreatments which blocked Lewis acid sites. Adsorption of ammonia and carbon dioxide on CsNaY during aldol condensation of n-butanal causes a decrease in rate. This result, along with the order of activity, suggests that the presence of both acid and basic sites produce higher activity than strongly basic MgO.Work performed at San Jose State University.     

Optimum composition of blast furnace slag as deduced from liquidus data for the quaternary system CaO-MgO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>

On the basis of liquidus measurements in the system CaO-MgO-Al₂O₃-SiO₂ and previously published data, diagrams have been constructed at 5 pct Al₂O₃ intervals from 5 to 35 pct Al₂O₃. Liquidus temperatures and primary phase fields are shown. The optimum composition of a blast furnace slag for a given alumina content is indicated. At the optimum point, ordinary slags will be entirely liquid and will have maximum desulphurization potential and minimum viscosity. The relation of optimum composition of slags to the “plateau region” of the liquidus surface, and the application of these data on synthetic quaternary slags to actual slag compositions are discussed. Index of refraction of glasses is given as well as composition, temperature, and phase data for each mixture.     

Topological Repairing of 3D Digital Images

We present here a new randomized algorithm for repairing the topology of objects represented by 3D binary digital images. By “repairing the topology”, we mean a systematic way of modifying a given binary image in order to produce a similar binary image which is guaranteed to be well-composed. A 3D binary digital image is said to be well-composed if, and only if, the square faces shared by background and foreground voxels form a 2D manifold. Well-composed images enjoy some special properties which can make such images very desirable in practical applications. For instance, well-known algorithms for extracting surfaces from and thinning binary images can be simplified and optimized for speed if the input image is assumed to be well-composed. Furthermore, some algorithms for computing surface curvature and extracting adaptive triangulated surfaces, directly from the binary data, can only be applied to well-composed images. Finally, we introduce an extension of the aforementioned algorithm to repairing 3D digital multivalued images. Such an algorithm finds application in repairing segmented images resulting from multi-object segmentations of other 3D digital multivalued images.

Magnetic compass fault detection method for GPS/INS/magnetic compass integrated navigation systems

This paper proposes a magnetic compass fault detection method for GPS/INS/Magnetic compass integrated navigation systems. The fault is assumed to be caused by the hard iron and soft iron effect and modeled as an abrupt change in the magnetic compass output. In order to detect the fault, a test statistic related with only azimuth error measurement is determined. When a fault is detected, the GPS/INS/Magnetic compass integrated navigation system is changed into a GPS/INS integrated navigation system mode. In order to show the validity of the proposed method, computer simulation and van testing are carried out. The simulation and van test results show that the proposed navigation system gives more accurate outputs than the GPS/INS/Magnetic compass without the proposed method.     

A scaled thickness conditioning for solid- and solid-shell discretizations of thin-walled structures

The numerical discretization of thin shell structures yields ill-conditioned stiffness matrices due to an inherent large eigenvalue spectrum. Finite element parametrization that depends on shell thickness, like relative displacement shells, solid shells and other solid finite elements even add to the ill-conditioning by introducing high eigenmodes.To overcome this numerical issue we present a scaled thickness conditioning (STC) approach, a mechanically motivated preconditioner for thin-walled structures discretized with continuum based element formulations. The proposed approach is motivated by the scaled director conditioning (SDC) method for relative displacement shell elements. In contrast to SDC, the novel STC approach yields a preconditioner for the effective linear system. It is applicable independently of element technology employed, coupling to other physical fields, boundary conditions applied and additional algebraic constraints and can be easily extended to multilayer shell formulations.The effect of the proposed preconditioner on the conditioning of the effective stiffness matrix and its eigenvalue spectrum is studied. It is shown that the condition number of the modified system becomes almost independent from the aspect ratio of the employed elements. The improved conditioning has a positive influence on the convergence behavior of iterative linear solvers. In particular, in combination with algebraic multigrid preconditioners the number of iterations could be decreased by more than 85% for some examples and the computation time could be reduced by about 60%.