bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Design of Fire Retardant Formulations: SMC Low Profile Formulations
Authors: Hernangil A. , Rodriguez M. , Leon L. M. , Ballestero J. , Alonso J. R. 
Published: April 2011

The problems originated by fire are important enough to carry out studies related to ignition, flame spread, combustibility, and smoke suppression for the purpose of obtaining materials with better fire behaviour. An improvement in fire properties can be achieved using fire retardants and smoke suppressants. Fire retardants can act by means of chemical reactions where the combustion presents radicals with high energy in the gas phase. They can also react physically by several methods: developing a layer which protects the material from ignition on the surface of the substrate, giving off non flammable gases such as H2O, CO2, SO2, HCl, etc., in order to dissolve the flammable gases and withdrawing the oxygen from the fire area in the gas phase, improving certain reactions such as endothermic ones or surface dehydrations. On the other hand, smoke suppressants can also act physically and chemically (by means of Red-Ox reactions) in the condensed and gas phases. The present work focuses on the study of SMC-LP(Sheet Moulding Compound Low Profile) materials which are widely used in sectors such as: automotive, transport and building. In SMC low profile process, the polyester resins are mixed with thermoplastic additives. In this way, the formulation obtained is called low profile due to the contraction inside the mould tends to zero. On the other hand, using the proper process it is possible to obtain fibre reinforced plastics formulations with different fire retardant and smoke suppressants. The main objective of the present work has been an exhaustive analysis of the possible effects and interactions in fire and mechanical properties due to the different fillers added. This study has been carried out by means of an experimental design with statistical analysis of the results. The scope is focused on a further optimisation of these sorts of materials, in order to obtain a wide range of suitable formulations.
A Semi-Analytical Method for the Calculation of the Elastic Micro-Fields in Plain Weave Fabric Composites Subjected to In-Plane Loading
Authors: Kuhn J. L. , Haan S. I. , Charalambides P. G. 
Published: April 2011

In this paper, a computationally efficient semi-analytical method is developed for the calculation of the elastic micro-fields dominating plain weave composites under remote in-plane loading. The framework needed to obtain analytical displacement estimates is derived using the Rayleigh-Ritz method for a composite plate with spatially varying laminate stiffnesses. The method is developed with the aid of a symmetric woven unit-cell geometry. Three separate boundary value problems, corresponding to remotely applied biaxial and uniaxial displacement, and simple shear boundary conditions are formulated. Unit-cell geometry and material characteristics for both polymer and ceramic matrix composites are incorporated in the formulation of the above boundary value problems. Extensive solution convergence studies are presented. As expected, convergence is shown to depend on the number of terms used in the Ritz series solution and the number of integration stations used to integrate the spatially laminate stiffnesses within the woven unit-cell geometry. Convergence results for the optimal selection of both of the above parameters are presented. The implications of the method's potential to yield accurate elastic microfields on the evolution of stress induced microdamage in woven systems is discussed.
A Variational Approach to Analyzing Laminates with Cracks and Viscoplasticity—The Model and its Validation
Authors: Gao Zhanjun , Xiang Xiaoyun 
Published: April 2011

For cross-ply laminates, matrix cracks and viscoplasticity of the 90 degree ply are two major forms of damage which affects the performance of the composite laminates, especially at high temperatures and under complicated loading patterns. To predict the durability of such kinds of materials, one of the tasks is to analyze stress distribution in each ply of the laminates taking into the interaction between the cracks and viscoplastic deformation. A unified viscoplasticity model is utilized together with the principle of minimum complementary energy to establish a general framework for cross-ply laminates containing cracks and undergoing general viscoplastic deformation. The problem is reduced to an ordinary differential equation for a stress function with an inhomogeneous "force" term related to the viscoplastic strain accumulation. An algorithm to solve the equation for the stress function is presented. The results are compared with those from the finite element method to validate the proposed approach. It is found that although the variational approach, like most of the analytical solutions, does not represent the near crack tip stress singularity field, it does provide fairly accurate through-thickness average stress within the 0 and 90 degree plies. In reality, local inelastic deformation occurs near the crack tip so that the stress is finite. If the local inelastic deformation near the crack tip is taken into consideration, the results from the variational approach match more closely with the finite element solution. Furthermore, the variational approach yields rather accurate in-plane shear stress along the interface between the 90 and 0 degree plies.
The Effective Elastic Properties in Anisotropic Composites with Ellipsoidal Inclusions
Authors: Demakos C. B. , Theocaris P. S. 
Published: April 2011

Parallel series of ellipsoidal inclusions, aligned along their major axes, whose centers are arranged in arrays inside a matrix, result generally in an orthotropic composite. When these arrays of inclusions constitute stacks placed at equal spacings through the thickness of the composite, the material is transformed into a transversely isotropic material. Considering this simplified problem, the effective elastic properties, i.e., the longitudinal and transverse elastic and shear moduli, as well as the respective Poisson's ratios, are evaluated in this paper. The solution of the problem was made in terms of the aspect ratio of the inclusions, their volume fraction and, finally, the succession of the constituent phases inside the composite. Employing Eshelby's theory for the stress field around a single ellipsoidal inhomogeneity, which is surrounded by the effective anisotropic composite medium, and Mori-Tanaka's concept for considering the mutual interaction of the neighboring inclusions inside the matrix, we evaluated the effective properties of composites containing ellipsoidal inclusions parallel dispersed inside the matrix. The whole analysis provides, in a closed-form solution, interesting results concerning the anisotropy, as well as the stiffness of anisotropic composites, reinforced with ellipsoidal inclusions. These findings reveal that the anisotropy is merely increased in composites consisting of soft matrices and reinforced by hard needle-shaped inclusions, whereas the stiffness is affected by both the shape of inclusions, as well as by their mutual concentrations. Furthermore, introduction of different constituent phases inside the composites indicated that intense variations of stiffness occur, especially for composites consisting of hard matrices containing soft inclusions. The results of the paper concerning effective elastic properties of anisotropic composites with ellipsoidal inclusions can be applied in case of unidirectional discontinuous fiber composites, where the fibers are simulated by ellipsoidal inclusions. Also, the evaluation of the elastic properties in hard composites with enough soft inclusions provide information for the mechanical as well as the fracture behavior of hard composites weakened by internal through cracks.
Axial Compression of Empty and Foam Filled Composite Conical Shells
Authors: Gupta N. K. , Velmurugan R. 
Published: April 2011

Experimental and theoretical studies of axial compression of both empty and foam filled glass fibre/polyester resin truncated conical shells are presented. An analysis is carried out to determine the mean crushing load and the crush length, i.e., the shell length crushed in a cycle of progressive crushing of the shell. The mean crushing load is obtained by equating the total energy involved in a crush cycle to the work done by the applied load. The expression for crush length is obtained by minimizing the total potential energy with respect to the crush length. The shells were made of short, randomly oriented glass fibre mats with polyester resin, and their cone angles were 9.50°, 140°, 18.40°, 21° and 450°. These were subjected to axial compression in the Instron machine at a cross head velocity of 2 mm/min. Their typical deformation histories, load-deformation behaviour and energy absorption characteristics are presented and influence thereon of the infill foam is discussed. Standard tensile specimens were made with the same lay up sequence and number of layers as in the actual conical shells. These were subjected to uni-axial tension test in Instron machine to obtain their tensile properties. The analytical results obtained compared well with the experimental results.
A Study of Negative Poisson's Ratio in Randomly Oriented Quasi-Isotropic Composite Laminates
Authors: Yeh Hsien-Liang , Yeh Hsien-Yang , Zhang Ruguang 
Published: April 2011

In isotropic materials, it is known that values of Poisson's ratio larger than one half are thermodynamically inadmissible, for such values would lead to negative strain energy under certain loads. Although a negative Poisson's ratio is not forbidden by thermodynamics, it is rare in crystalline solids. With the development of modem fiber reinforced composite materials, the effective Poisson's ratio of laminated fiber reinforced composites shows a peculiar behavior as it becomes larger than one half or less than zero. In this article, a study of negative in-plane Poisson's ratio for a general class of randomly-oriented composite laminates is presented. A simple random statistical analysis has been presented. It is demonstrated that composite laminates with negative in-plane Poisson's ratio could be achieved by using the specific values of independent elastic constants E1, E2, G12, and v12 in each lamina. Also, the influence of the lamina material properties to the negative in-plane Poisson's ratio of the composite laminates is presented. The results from this statistical analysis provide a set of general guidelines for designing composite laminates with a special character-the negative in-plane Poisson's ratio.
Strength of Adhesively-Bonded Thbular Single Lap Carbon/Epoxy Composite-Steel Joints
Authors: Kim Young Goo , Oh Je Hoon , Lee Dai Gil 
Published: April 2011

The static tensile load bearing capability of adhesively-bonded tubular single lap joints if calculated using the linear mechanical adhesive properties is usually less than the experimentally determined one because the majority of the load transfer of adhesively-bonded joints is accomplished by the nonlinear behavior of the rubber-toughened epoxy adhesive. In this paper, both nonlinear mechanical properties and fabrication residual thermal stresses of adhesive were included in the stress calculation of adhesively-bonded tubular single lap carbon/epoxy composite-steel joints. During calculation, nonlinear tensile properties of adhesive were approximated by an exponential equation that was represented by the initial tensile modulus and ultimate tensile strength of adhesive obtained from tensile tests. From the tensile tests and the stress analyses of adhesively-bonded tubular single lap carbon/epoxy composite-steel joints with respect to stacking angles of carbon/epoxy composite adherends, the failure model for the adhesively-bonded tubular single lap carbon/epoxy composite-steel joint under the axial tensile load was proposed with considering fabrication residual thermal stresses.
Sleep Quality and Quality of Life in Adults With Type 2 Diabetes
Authors: Luyster Faith S. , Dunbar-Jacob Jacqueline 
Published: April 2011

Purpose The purpose of this study was to examine the relationship between sleep quality and health-related and diabetes-related quality of life in adults with type 2 diabetes. Methods Three hundred individuals with type 2 diabetes (mean age 63.9 years) completed questionnaires assessing sleep quality, health-related quality of life, diabetes-related quality of life, comorbidities, and depressive symptoms. Results More than half of the participants (55%) were “poor sleepers” according to the Pittsburgh Sleep Quality Index. After controlling for covariates, poor sleep quality was found to be a significant predictor of lower health-related quality of life as indicated by lower scores on both the physical and mental component scores of the Medical Outcomes Study 36-item Short Form health survey (SF-36). Poor sleep quality was also associated with worse diabetes-related quality of life, in particular lower scores on the Diabetes Quality of Life measure total score and the Satisfaction With Treatment and Diabetes Impact subscale scores. Conclusions These results suggest that poor sleep is common in type 2 diabetes and may adversely impact quality of life. Interventions to improve sleep hygiene can be suggested to patients by diabetes educators as part of diabetes self-management education programs.
Nursing Practice Patterns: Timing of Insulin Administration and Glucose Monitoring in the Hospital
Authors: Freeland Barbara , Penprase Barbara B. , Anthony Maureen 
Published: April 2011

Purpose The purpose of this study was to describe diabetes nursing practice patterns related to the timing of morning insulin administration, blood glucose monitoring, and meal intake for patients with type 2 diabetes and to report how frequently nurses were able to meet the expected standard of care. Methods Observations were made of 50 incidents of morning diabetes care on medical-surgical units in an acute care setting. Timeliness of rapid-acting insulin administration and glucose monitoring in relation to the morning meal were evaluated, as were the subsequent prelunch glucose levels. Results Patients did not receive rapid-acting insulin with in the standard recommended time of 10 minutes premeal/postmeal 84% of the time, nor did they receive glucose monitoring within the recommended 30 minutes premeal 57% of the time. There was no significant relationship found between timely insulin administration and glucose monitoring. There were no significant relationships found between care activities and prelunch glucose control or glucose variability. Conclusions Coordinating insulin administration, glucose monitoring, and meal delivery within the tight time frames required for rapid-acting insulin is a significant challenge not being met. Timeliness of diabetes nursing care is not the sole determining factor to good glucose control in hospitalized patients. Standards regarding timing of these activities need to be evaluated.
BCL-2 (-938C > A) polymorphism is associated with breast cancer susceptibility
Authors: Zhang Ning , Li Xiaoyan , Tao Kai , Jiang Liyu , Ma Tingting , Yan Shi , Yuan Cunzhong , Moran Meena S , Liang Faming , Haffty Bruce G , Yang Qifeng 
Published: April 2011

Abstract

Background

BCL-2 (B-cell leukemia/lymphoma 2) gene has been demonstrated to be associated with breast cancer development and a single nucleotide polymorphism (SNP; -938C > A) has been identified recently. To investigate whether this polymorphism functions as a modifier of breast cancer development, we analyzed the distribution of genotype frequency, as well as the association of genotype with clinicopathological characteristics. Furthermore, we also studied the effects of this SNP on Bcl-2 expression in vitro.

Methods
We genotyped the BCL-2 (-938C > A) in 114 patients and 107 controls, and analyzed the estrogen receptor (ER), progestogen receptor (PR), C-erbB2 and Ki67 status with immunohistochemistry (IHC). Different Bcl-2 protein levels in breast cancer cell lines were determined using western blot. Logistic regression model was applied in statistical analysis.

Results
We found that homozygous AA genotype was associated with an increased risk (AA vs AC+CC) by 2.37-fold for breast cancer development and significant association was observed between nodal status and different genotypes of BCL-2 (-938C > A) (p = 0.014). AA genotype was more likely to develop into lobular breast cancer (p = 0.036). The result of western blot analysis indicated that allele A was associated with the lower level of Bcl-2 expression in breast cancer cell lines.

Conclusions
AA genotype of BCL-2 (-938C > A) is associated with susceptibility of breast cancer, and this genotype is only associated with the nodal status and pathological diagnosis of breast cancer. The polymorphism has an effect on Bcl-2 expression but needs further investigation.
Plasmodium Cysteine Repeat Modular Proteins 3 and 4 are essential for malaria parasite transmission from the mosquito to the host
Authors: Douradinha Bruno , Augustijn Kevin D , Moore Sally G , Ramesar Jai , Mota Maria M , Waters Andrew P , Janse Chris J , Thompson Joanne 
Published: April 2011

AbstractBackgroundThePlasmodiumCysteine Repeat Modular Proteins (PCRMP) are a family of four conserved proteins of malaria parasites, that contain a number of motifs implicated in host-parasite interactions. Analysis of mutants of the rodent parasitePlasmodium bergheilacking expression of PCRMP1 or 2 showed that these proteins are essential for targeting ofP. bergheisporozoites to the mosquito salivary gland and, hence, for transmission from the mosquito to the mouse.MethodsIn this work, the role of the remaining PCRMP family members, PCRMP3 and 4, has been investigated throughout thePlasmodiumlife cycle by generation and analysis ofP. bergheigene deletion mutants, Δpcrmp3 and Δpcrmp4. The role of PCRMP members during the transmission and hepatic stages of thePlasmodiumlifecycle has been evaluated by light- and electron microscopy and by analysis of liver stage development in HEPG2 cellsin vitroand by infecting mice with mutant sporozoites. In addition, mice were immunized with live Δpcrmp3 and Δpcrmp4 sporozoites to evaluate their immunization potential as a genetically-attenuated parasite-based vaccine.ResultsDisruption ofpcrmp3andpcrmp4inP. bergheirevealed that they are also essential for transmission of the parasite through the mosquito vector, although acting in a distinct way topbcrmp1and2. Mutants lacking expression of PCRMP3 or PCRMP4 show normal blood stage development and oocyst formation in the mosquito and develop into morphologically normal sporozoites, but these have a defect in egress from oocysts and do not enter the salivary glands. Sporozoites extracted from oocysts perform gliding motility and invade and infect hepatocytes but do not undergo further development and proliferation. Furthermore, the study shows that immunization with Δcrmp3and Δcrmp4sporozoites does not confer protective immunity upon subsequent challenge.ConclusionsPCRMP3 and 4 play multiple roles during thePlasmodiumlife cycle; they are essential for the establishment of sporozoite infection in the mosquito salivary gland, and subsequently for development in hepatocytes. However, although Δpcrmp3and Δpcrmp4parasites are completely growth-impaired in the liver, immunization with live sporozoites does not induce the protective immune responses that have been shown for other genetically-attenuated parasites.
Stability and rheology of dilute TiO2-water nanofluids
Authors: Penkavova Vera , Tihon Jaroslav , Wein Ondrej 
Published: April 2011

AbstractThe apparent wall slip (AWS) effect, accompanying the flow of colloidal dispersions in confined geometries, can be an important factor for the applications of nanofluids in heat transfer and microfluidics. In this study, a series of dilute TiO2 aqueous dispersions were prepared and tested for the possible presence of the AWS effect by means of a novel viscometric technique. The nanofluids, prepared from TiO2 rutile or anatase nanopowders by ultrasonic dispersing in water, were stabilized by adjusting the pH to the maximum zeta potential. The resulting stable nanofluid samples were dilute, below 0.7 vol.%. All the samples manifest Newtonian behavior with the fluidities almost unaffected by the presence of the dispersed phase. No case of important slip contribution was detected: the Navier slip coefficient of approximately 2 mm Pa-1 s-1 would affect the apparent fluidity data in a 100-μm gap by less than 1%.
Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers
Authors: Mercatelli Luca , Sani Elisa , Zaccanti Giovanni , Martelli Fabrizio , Di Ninni Paola , Barison Simona , Pagura Cesare , Agresti Filippo , Jafrancesco David 
Published: April 2011

AbstractIn the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device.
PACS
78.40.Ri, 78.35.+c, 78.67.Bf, 88.40.fh, 88.40.fr, 81.05.U.