Thermal, rheological, and structural behaviors of natural and modified cassava starch granules, with sodium hypochlorite solutions

The use of chemically modified starches is widely accepted in various industries, with several applications. In this research, natural cassava starch granules were treated with standard sodium hypochlorite solution at 0.8, 2.0, and 5.0 g Cl/100 g starch. The native and modified starch samples were investigated by means of the following techniques: simultaneous thermogravimetry-differential thermal analysis, which allowed us to verify the thermal decomposition associated with endothermic or exothermic phenomena; and differential scanning calorimetry that was used to determine gelatinization enthalpy as well as the rapid viscoamylographic analysis that provided the pasting temperature and viscosity. By means of non-contact-atomic force microscopy method and X-ray powder patterns diffractometry, it was possible to observe the surface morphology, topography of starch granules, and alterations in the granules' crystallinity. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Structural relationships in the solid state of the anti-chagas agent (E)-phenylethenylbenzofuroxan

The crystal structure and the vibrational spectrum of a potential drug for Chagas`s disease treatment, the (E)-isomer of phenylethenylbenzofuroxan 1 (5(6)(E)-[(2-phenylethenyl)]benzo[1,2-c]1,2,5-oxadiazole N-oxide), are reported. In order to provide insights into structural relationships, quantum mechanical calculations were employed starting from crystal structure. These results have given theoretical support to state interesting structural features, such as the effect of some intermolecular contacts on the molecule conformation and the electronic delocalization decreasing through atoms of the benzofuroxan moiety. Furthermore, the MOGUL comparative analysis in the Cambridge Structural Database provided additional evidences on these structural behaviors of compound 1. Intermolecular contacts interfere on the intramolecular geometry, as, for instance, on the phenyl group orientation, which is twisted by 12.32(6)A degrees from the ethenylbenzofuroxan plane. The experimental Raman spectrum of compound 1 presents unexpected frequency shift and also anomalous Raman activities. At last, the molecule skeleton deformation and the characteristic vibrational modes were correlated by matching the experimental Raman spectrum to the calculated one.

Geotechnical and structural behavior of the railroad track in large-scale apparatus

This paper analyses the static and dynamic behavior of the railroad track model in laboratory. Measurements of stresses and strains on a large-scale railroad track apparatus were studied. The model includes: compacted soil, representing the final layers of platform, ballast layer, and ties (steel, wooden, and pre-stressed concrete). The soil and soil ballast interface were instrumented with pneumatic stress gauge. Settlement measurement device were positioned at the same levels as the load cells. Loads were applied by hydraulic actuators, statically and dynamically. After the prescribed number of load cycles, in pre-determined intervals, stresses and strains were measured. Observations indicate that stress and strain distributions, transmitted by wooden or steel ties, behave similarly. A more favorable behavior was observed with pre-stressed concrete mono block ties. Non-linear response was observed after a threshold numbers of cycles were surpassed, showing that the strain modulus increases with the numbers of cycles. © 2009 IOS Press.

Influence of ethanol and glycerol concentration over functional and structural properties of zein-oleic acid films

This study was performed in order to determine the effect of the addition of different concentrations of glycerol and ethanol over functional and structural properties of zein-oleic acid films. Films were prepared from zein and oleic acid formulations, containing: 0, 10, 20 and 30% (w/w) of glycerol as plasticizer and 75, 80, 85, 90 and 95% (v/v) of ethanol as zein solvent. Water vapor permeability (WVP) at 4 and 24 C, opacity, water solubility and structural behavior of the film were assessed. The film water barrier properties, WVP and water solubility, were increased when higher ethanol concentration and lower glycerol concentration were used. Furthermore, WVP at 4 C was lower than WVP at 24 C due to the crystalline solid state of oleic acid at lower temperatures. Likewise, opacity, homogeneity and structure of the composite film were improved as ethanol increased and glycerol lowered. © 2013 Elsevier B.V. All rights reserved.

Steel–concrete–steel sandwich system in Arctic offshore structure: Materials, experiments, and design

The gravity based structure (GBS) with external Steel–Concrete–Steel (SCS) sandwich ice-resistant wall has been developed for the Arctic oil and gas drilling. This paper firstly reported the experimental studies on the mechanical properties of steel and concretes under Arctic low temperature. With the test data, design equations were developed to incorporate the influences of the low temperature on these mechanical properties. Two types of Arctic GBS structure with flower-conical SCS sandwich shell type and plate type of ice-resistant wall have been developed for the Arctic offshore structure. Besides the studies on the materials, two SCS sandwich prototype shells and plates were, respectively, prepared and tested under patch loading that simulated the localized ice-contact pressure. The structural behaviors of the SCS sandwich structure under patch loading were reported and discussions were made on the influences of different parameters on the structural behavior of the structure. Analytical models were developed to predict the punching shear resistances of the SCS sandwich structure through modifying the code provisions. The accuracies of the developed analytical models were checked through validations against 27 tests in the literature. Corresponding design procedures on resistances of SCS sandwich structure were recommended based on these discussions and validations.

Membrane-bound alkaline phosphatase from ectopic mineralization and rat bone marrow cell culture

Cells from rat bone marrow exhibit the proliferation-differentiation sequence of osteoblasts, form mineralized extracellular matrix in vitro and release alkaline phosphatase into the medium. Membrane-bound alkaline phosphatase was obtained by method that is easy to reproduce, simpler and fast when compared with the method used to obtain the enzyme from rat osseous plate. The membrane-bound alkaline phosphatase from cultures of rat bone marrow cells has a MWr of about 120 kDa and specific PNPP activity of 1200 U/tng. The ecto-enzyme is anchored to the plasma membrane by the GPI anchor and can be released by PIPLC (selective treatment) or polidocanol (0.2 mg/mL protein and 1% (w/v) detergent). The apparent optimum pH for PNPP hydrolysis by the enzyme was pH 10. This fraction hydrolyzes ATP (240 U/mg), ADP (350 U/ mg), glucose 1-phosphate (1100 U/mg), glucose 6-phosphate (340 Wing), fructose 6-phosphate (460 U/mg), pyrophosphate (330 U/mg) and (3glycerophosphate (600 U/mg). Cooperative effects were observed for the hydrolysis of PPi and beta-glycerophosphate. PNPPase activity was inhibited by 0.1 mM vanadate (46%), 0.1 mM ZnCl2 (68%), 1 mM levamisole (66%), 1 mM arsenate (44%), 10 mM phosphate (21%) and 1 mM theophylline (72%). We report the biochemical characterization of membrane-bound alkaline phosphatase obtained from rat bone marrow cells cultures, using a method that is simple, rapid and easy to reproduce. Its properties are compared with those of rat osseous plate enzyme and revealed that the alkaline phosphatase obtained has some kinetics and structural behaviors with higher levels of enzymatic activity, facilitating the comprehension of the mineralization process and its function. (c) 2006 Elsevier B.V. All rights reserved.

When small is different: The case of membranes inside tubes

Recently, classical elasticity theory for thin sheets was used to demonstrate the existence of a universal structural behavior describing the confinement of sheets inside cylindrical tubes. However, this kind of formalism was derived to describe macroscopic systems. A natural question is whether this behavior still holds at nanoscale. In this work, we have investigated through molecular dynamics simulations the structural behavior of graphene and boron nitride single layers confined into nanotubes. Our results show that the class of universality observed at macroscale is no longer observed at nanoscale. The origin of this discrepancy is addressed in terms of the relative importance of forces and energies at macro and nano scales. © 2012 Materials Research Society.

Unraveling the Conformational Determinants of Peptide Dendrimers Using Molecular Dynamics Simulations

Peptide dendrimers are synthetic tree-like molecules composed of amino acids. There are at least two kinds of preferential structural behaviors exhibited by these molecules, which acquire either compact or noncompact shapes. However, the key structural determinants of such behaviors remained, until now, unstudied. Herein, we conduct a comprehensive investigation of the structural determinants of peptide dendrimers by employing long molecular dynamics simulations to characterize an extended set of third generation dendrimers. Our results clearly show that a trade-off between electrostatic effects and hydrogen bond formation controls structure acquisition in these systems. Moreover, by selectively changing the dendrimers charge we are able to manipulate the exhibited compactness. In contrast, the length of branching residues does not seem to be a major structural determinant. Our results are in accordance with the most recent experimental evidence and shed some light on the key molecular level interactions controlling structure acquisition in these systems. Thus, the results presented constitute valuable insights that can contribute to the development of truly tailor-made dendritic systems.

A Unique Prestressed Concrete Pedestrian Bridge in Spain

This paper describes the so-called Kiss Bridge. This structure resembles a kiss, a subtle touch of structures. The beams have been structurally designed to adapt the Japanese art of paper folding called "origami." The material used for constructing the floating beams is white reinforced concrete in the form of folded shells. The two geometrically different parts have distinct structural behaviors. The length of the main pathway of both structures is over 60 m. The pedestrian bridge crosses an artificial rainwater channel with a skew of 45° with respect to the referred channel. The joint between the cantilever structure and the Y-shaped one is located over the middle of the channel. Each stretch has different transversal sections. The pedestrian bridge is made with prestressed self-compacting reinforced concrete of 60 MPa. The foundation is shallow, comprising footings and footing beams made of 25 MPa conventional concrete. The cantilever structure with its foundations is designed as a semi-integral bridge whereas the Y-shaped one is an integral structure. The dynamic behavior of the structure was carefully studied to ensure that the dynamic loads generated by pedestrians do not cause excessive vibrations, especially to the cantilever structure, which could present dynamic interactions with the pedestrians walking. The bridge was recognized, in the 2014 edition of the fib Awards for Outstanding Concrete Structures, for having made a valuable contribution to the image and promotion of concrete structures.

Investigation of high cycle and Very-High-Cycle Fatigue behaviors for a structural steel with smooth and notched specimens

The high cycle and Very-High-Cycle Fatigue (VHCF) properties of a structural steel with smooth and notched specimens were studied by employing a rotary bending machine with frequency of 52.5 Hz. For smooth specimens, VHCF failure did occur at fatigue cycles of 7.1 x 10(8) with the related S-N curve of stepwise tendency. Scanning Electron Microscopy (SEM) was used for the observations of the fracture surfaces It shows that for smooth specimens the crack origination is surface mode in the failure regime of less than 10(7) cycles While at VHCF regime, the material failed from the nonmetallic inclusion lies in the interior of material, leading to the formation of fisheye pattern. The dimensions of crack initiation region were measured and discussed with respect to the number of cycles to failure. The mechanism analysis by means of low temperature fracture technique shows that the nonmetallic inclusion in the interior of specimen tends to debond from surrounding matrix and form a crack. The crack propagates and results to the final failure. The stress intensity factor and fatigue strength were calculated to investigate the crack initiation properties. VHCF study on the notched specimens shows that the obtained S-N curve decreases continuously. SEM analysis reveals that multiple crack origins are dominant on specimen surface and that fatigue crack tends to initiate from the surface of the specimen. Based on the fatigue tests and observations, a model of crack initiation was used to describe the transition of fatigue initiation site from subsurface to surface for smooth and notched specimens. The model reveals the influences of load, grain size, inclusion size and surface notch on the crack initiation transition. (C) 2010 Elsevier Ltd. All rights reserved

Structural characteristics and redox behaviors of Ce1-xCuxOy solid solutions

Nanosized Ce1-xCuxOy materials were prepared by complexation-combustion method. The structural characteristics and redox behaviors were investigated using X-ray diffraction (XRD), temperature programmed reduction (H-2-TPR), UV-Vis, and Raman spectroscopies. In XRD patterns, no evidence of CuO diffraction peaks are observed for the Ce1-xCuxOy samples calcinated at 650 degreesC for 5 h, until the Cu/(Ce + Cu) ratio is higher than 0.4. The stepwise decrease of the 2theta value of CeO2 in Ce1-xCuxOy with the increasing of Cu concentration suggests that the CU2+ ions incorporate into the CeO2 lattice to form Ce1-xCuxOy solid solutions for low Cu/(Ce + Cu) ratios (x less than or equal to 0.1). The CuO phase begins to segregate from the solid solutions with the further increasing of Cu/(Ce+Cu) ratio. The Raman mode at 1176 cm(-1) ascribed to the enhanced defects appears for CeO2 and the Ce0.9Cu0.1Oy solid solution. Compared with CeO2 alone, the Raman mode of cubic CeO2 shifts from 462 to 443 cm(-1) for the Ce0.9Cu0.1Oy solid solution. The H-2 consumption of the fresh Ce0.95Cu0.05Oy is 1.65 times higher than that needed to reduce CuO to Cu, and it increases to 2.4 after a reoxidation of the partially reduced Ce0.95Cu0.05Oy at 300 degreesC, which indicates that the CeO2 phase is also extensively reduced. Compared with the high Cu/(Ce+Cu) ratio sample Ce0.7Cu0.3Oy, the Ce0.9Cu0.1Oy solid solution shows high and stable redox property even after different reoxidation temperatures. When the reoxidation temperature exceeds 200 degreesC, the a peak (similar to170 degreesC) ascribed to the reduction of surface oxygen disappears, and the P peak (similar to190 degreesC) ascribed to the reduction of Cu2+ species and the partial reduction of bulk CeO2 shifts to higher temperatures with the H-2 consumption 1.16 times higher than that for fresh sample. The result demonstrates that the redox property of the CeO2 is Significantly improved by forming the Ce1-xCuxOy solid solutions.

Influence of intermolecular entanglements on the glass transition and structural relaxation behaviors of macromolecules. 2. Polystyrene and phenolphthalein poly(ether sulfone)

The effect of entanglements on the glass transition and structural relaxation behaviors has been studied for polystyrene (PS) and phenolphthalein poly(ether sulfone) (PES-C) samples by fast evaporation of the solution of concentrations varying from above the overlapping concentration to far below it, and compared to the results we have studied previously in PC. It has been found that for all the polymers we have studied, in the concentrated solution region, the T-g of the samples obtained from solution are independent of the change of concentration and are very close to that of normal bulk samples, whereas in the dilute solution region the T-g of the samples decrease with the logarithm of decreasing concentration. The critical concentrations that divide the two distinct regions for the three polymers are 0.9% g/mL for PC, 0.1% g/mL for PS, and 1% g/mL for PES-C. The decrease of T-g of the samples is interpreted by the decrease of intermolecular entanglements as the isolation of polymer chains, and the entanglement of polymer chains restrained the mobility of the segments. The structural relaxation behavior of the polymers is also found to be different from that of normal bulk samples. The enthalpies of single-chain samples are lower than that of the bulk ones, which correspond to the lower glass transition temperature; the peaks are lower and broader, and the relaxed enthalpy is much lower as compared to that of bulk samples. In the three polymers we have studied, the influence of change of entanglements on both the decrease in glass transition temperature and relaxed enthalpy is the most significant for PS and the least for PES-C. It is indicated that the interactions in the flexible polymers are weak; thus, the restraint of the entanglements on the mobility of the segments plays a more important role in the flexible polymers, and the change of entanglement in the flexible polymers has a more significant influence on the physical properties.

Influence of entanglements an the glass transition and structural relaxation behaviors of macromolecules. 1. Polycarbonate

We obtained the single-chain polycarbonate sample, by a new fast evaporation method and found that the polycarbonate sample obtained by this method is completely amorphous, while the polycarbonate sample obtained by other methods all have a certain degree of crystallinity. The glass transition temperature (T-g) of the sample decreases with the decreasing of concentration when the concentration of the prepared solution is below the critical value. The critical concentration we obtained from the T-g dependence of concentration is 0.9% g/mL and is in accord with that obtained by viscometry and light scattering methods directly from the solution. The structural relaxation behavior is found also different from that of a normal bulk sample of polycarbonate. The enthalpic peak of the single-chain sample is lower: than that of the bulk one, which corresponds to the lower glass transition temperature. The peak of the single-chain sample is lower and broader, and the relaxed enthalpy is much lower compared with that of the bulk sample. These results have been explained in terms of the effect of entanglement on the mobility of the segments in polymer and the compact conformation in the single-chain sample.

Concurrent multi-scale modeling of civil infrastructures for analyses on structural deterioration—Part I : Modeling methodology and strategy

This paper aims to develop the methodology and strategy for concurrent finite element modeling of civil infrastructures at the different scale levels for the purposes of analyses of structural deteriorating. The modeling strategy and method were investigated to develop the concurrent multi-scale model of structural behavior (CMSM-of-SB) in which the global structural behavior and nonlinear damage features of local details in a large complicated structure could be concurrently analyzed in order to meet the needs of structural-state evaluation as well as structural deteriorating. In the proposed method, the “large-scale” modeling is adopted for the global structure with linear responses between stress and strain and the “small-scale” modeling is available for nonlinear damage analyses of the local welded details. A longitudinal truss in steel bridge decks was selected as a case to study how a CMSM-of-SB was developed. The reduced-scale specimen of the longitudinal truss was studied in the laboratory to measure its dynamic and static behavior in global truss and local welded details, while the multi-scale models using constraint equations and substructuring were developed for numerical simulation. The comparison of dynamic and static response between the calculated results by different models indicated that the proposed multi-scale model was found to be the most efficient and accurate. The verification of the model with results from the tested truss under the specific loading showed that, responses at the material scale in the vicinity of local details as well as structural global behaviors could be obtained and fit well with the measured results. The proposed concurrent multi-scale modeling strategy and implementation procedures were applied to Runyang cable-stayed bridge (RYCB) and the CMSM-of-SB of the bridge deck system was accordingly constructed as a practical application.

The HealthyTexts study : A randomized controlled trial to improve skin cancer prevention behaviors among young people

Several randomized trials have found behavior change programs delivered via text messaging to be efficacious to improve preventive health behaviors such as physical activity and stopping smoking; however few have assessed its value in skin cancer prevention or early detection. The HealthyTexts study enrolled 678 participants 18–42 years, and assigned them to receive 21 text messages about skin cancer prevention, skin self-examination or physical activity(attention control) over the course of one year. Baseline data have been collected and outcomes will be assessed at three months and twelve months post intervention. The trial aims to increase the mean overall sun protection habits index score from 2.3 to 2.7 with a standard deviation of 0.5 (effect size of 0.5) and the proportion of people who conduct a whole-body skin self-examination by an absolute 10%. This paper describes the study design and participants' baseline characteristics. In addition, participants' goals for their health, and strategies they apply to achieve those goals are summarized.