Glycolipids form materials of considerable potential for a wide range of surfactant and thin film applications. Understanding the effect of glycolipid covalent structure on the properties of their thermotropic and lyotropic assemblies is a key step toward rational design of new glycolipid-based materials. Here, we perform molecular dynamics simulations of anhydrous bilayers of dodecyl β-maltoside, dodecyl β-cellobioside, dodecyl β-isomaltoside, and a C(12)C(10) branched β-maltoside. Specifically, we examine the consequences of chain branching and headgroup identity on the structure and dynamics of the lamellar assemblies. Chain branching of the glycolipid leads to measurable differences in the dimensions and interactions of the lamellar assembly, as well as a more fluid-like hydrophobic chain region. Substitution of the maltosyl headgroup of βMal-C(12) by an isomaltosyl moiety leads to a significant decrease in bilayer spacing as well as a markedly altered pattern of inter-headgroup hydrogen bonding. The distinctive simulated structures of the two regioisomers provide insight into the difference of ~90 °C in their observed clearing temperatures. For all four simulated glycolipid systems, with the exception of the sn-2 chain of the branched maltoside, the alkyl chains are ordered and exhibit a distinct tilt, consistent with recent crystallographic analysis of a branched chain Guerbet glycoside. These insights into structure-property relationships from simulation provide an important molecular basis for future design of synthetic glycolipid materials.
Polymorphisms of Helicobacter pylori cagA and vacA genes do exist and may contribute to differences in H. pylori infection and gastroduodenal diseases among races in the Malaysian population. This study was conducted to characterize the polymorphisms in H. pylori cagA and vacA in Malaysian population.
Eurycoma longifolia (EL) has been shown recently to protect against bone calcium loss in orchidectomised rats, the model for androgen-deficient osteoporosis. The mechanism behind this is unclear but it may be related to its ability to elevate testosterone levels or it may directly affect bone remodeling. The aim of this study is to determine the mechanism involved by investigating the effects of EL extract on serum testosterone levels, bone biomarkers, biomechanical strength and gene expression of Receptor Activator of Nuclear Factor kappa-B ligand (RANKL), Osteoprotegerin (OPG) and Macrophage-Colony Stimulating Factor (MCSF) in orchidectomised rats.
The interactions of p-cresol photocatalytic degradation components were studied by response surface methodology. The study was designed by central composite design using the irradiation time, pH, the amount of photocatalyst and the p-cresol concentration as variables. The design was performed to obtain photodegradation % as actual responses. The actual responses were fitted with linear, two factor interactions, cubic and quadratic model to select an appropriate model. The selected model was validated by analysis of variance which provided evidences such as high F-value (845.09), very low P-value (
This study was undertaken in order to identify the best culture strategy to expand and osteogenic differentiation of human bone marrow stem cells (hBMSCs) for subsequent bone tissue engineering. In this regard, the experiment was designed to evaluate whether it is feasible to bypass the expansion phase during hBMSCs differentiation towards osteogenic lineages by early induction, if not identification of suitable culture media for enhancement of hBMSCs expansion and osteogenic differentiation. It was found that introduction of osteogenic factors in alpha-minimum essential medium (αMEM) during expansion phase resulted in significant reduction of hBMSCs growth rate and osteogenic gene expressions. In an approach to identify suitable culture media, the growth and differentiation potential of hBMSCs were evaluated in αMEM, F12:DMEM (1:1; FD), and FD with growth factors. It was found that αMEM favors the expansion and osteogenic differentiation of hBMSCs compared to that in FD. However, supplementation of growth factors in FD, only during expansion phase, enhances the hBMSCs growth rate and significantly up-regulates the expression of CBFA-1 (the early markers of osteogenic differentiation) during expansion, and, other osteogenic genes at the end of induction compared to the cells in αMEM and FD. These results suggested that the expansion and differentiation phase of the hBMSCs should be separately and carefully timed. For bone tissue engineering, supplementation of growth factors in FD only during the expansion phase was sufficient to promote hBMSCs expansion and differentiation, and preferably the most efficient culture condition.
Poor adherence to prescribed medications is a major cause for treatment failure, particularly in chronic diseases such as hypertension. This study was conducted to assess adherence to medications in patients undergoing hypertensive treatment in the Primary Health Clinics of the Ministry of Health in Malaysia. Factors affecting adherence to medications were studied, and the effect of nonadherence to blood pressure control was assessed.
Research on joint torque reduction in robot manipulators has received considerable attention in recent years. Minimizing the computational complexity of torque optimization and the ability to calculate the magnitude of the joint torque accurately will result in a safe operation without overloading the joint actuators. This paper presents a mechanical design for a three dimensional planar redundant manipulator with the advantage of the reduction in the number of motors needed to control the joint angle, leading to a decrease in the weight of the manipulator. Many efforts have been focused on decreasing the weight of manipulators, such as using lightweight joints design or setting the actuators at the base of the manipulator and using tendons for the transmission of power to these joints. By using the design of this paper, only three motors are needed to control any n degrees of freedom in a three dimensional planar redundant manipulator instead of n motors. Therefore this design is very effective to decrease the weight of the manipulator as well as the number of motors needed to control the manipulator. In this paper, the torque of all the joints are calculated for the proposed manipulator (with three motors) and the conventional three dimensional planar manipulator (with one motor for each degree of freedom) to show the effectiveness of the proposed manipulator for decreasing the weight of the manipulator and minimizing driving joint torques.
MeSH terms: Algorithms; Attention; Automobile Driving; Body Weights and Measures; Robotics; Tendons; Torque
Magnetic Induction Tomography (MIT), which is also known as Electromagnetic Tomography (EMT) or Mutual Inductance Tomography, is among the imaging modalities of interest to many researchers around the world. This noninvasive modality applies an electromagnetic field and is sensitive to all three passive electromagnetic properties of a material that are conductivity, permittivity and permeability. MIT is categorized under the passive imaging family with an electrodeless technique through the use of excitation coils to induce an electromagnetic field in the material, which is then measured at the receiving side by sensors. The aim of this review is to discuss the challenges of the MIT technique and summarize the recent advancements in the transmitters and sensors, with a focus on applications in biological tissue imaging. It is hoped that this review will provide some valuable information on the MIT for those who have interest in this modality. The need of this knowledge may speed up the process of adopted of MIT as a medical imaging technology.
MeSH terms: Humans; Magnetics/instrumentation*; Organ Specificity*; Signal Processing, Computer-Assisted/instrumentation*; Tomography/instrumentation*; Biosensing Techniques/instrumentation*; Imaging, Three-Dimensional/instrumentation*
Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO(2), TiO(2), In(2)O(3), WO(x), AgVO(3), CdO, MoO(3), CuO, TeO(2) and Fe(2)O(3). Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research.
The past few years have witnessed increased interest among researchers in cluster-based protocols for homogeneous networks because of their better scalability and higher energy efficiency than other routing protocols. Given the limited capabilities of sensor nodes in terms of energy resources, processing and communication range, the cluster-based protocols should be compatible with these constraints in either the setup state or steady data transmission state. With focus on these constraints, we classify routing protocols according to their objectives and methods towards addressing the shortcomings of clustering process on each stage of cluster head selection, cluster formation, data aggregation and data communication. We summarize the techniques and methods used in these categories, while the weakness and strength of each protocol is pointed out in details. Furthermore, taxonomy of the protocols in each phase is given to provide a deeper understanding of current clustering approaches. Ultimately based on the existing research, a summary of the issues and solutions of the attributes and characteristics of clustering approaches and some open research areas in cluster-based routing protocols that can be further pursued are provided.
The title mol-ecule, C(10)H(9)NO, is almost planar with an r.m.s. deviation for all non-H atoms of 0.0115 Å. In the crystal, mol-ecules are connected through N-H⋯O hydrogen bonds into chains running along [021]. The chains are further connected via C-H⋯π inter-actions, forming layers in the bc plane.
Fibrin sheath formation around long-term haemodialysis catheter is a common cause of failed dialysis access. Treatment options include pharmacological and mechanical methods. This paper reports a case of failed dialysis access due to fibrin sheath encasement. Pharmacologic thrombolysis, mechanical disruption using guide wire and catheter exchange had failed to address the issue. Eventually, fibrin sheath stripping using the loop snare technique was able to successfully restore the catheter function.
Radiology is a relatively high-cost and high-maintenance aspect of medicine. Expertise is constantly required, from acquisition to its use and quality assurance programmes. However, it is an integral part of healthcare practice, from disease diagnosis, surveillance and prevention to treatment monitoring. It is alarming that two thirds of the world is deficient in or lacks even basic diagnostic imaging. Developing and underdeveloped countries need help in improving medical imaging. Help is coming from various organisations, which are extending hands-on teaching and imparting knowledge, as well as training trainers to increase the pool of skilled practitioners in the use of imaging equipment and other aspects of radiology services. The scene for social radiology is changing and set to positively impact the world in the (near) future.
Diagnosing acute appendicitis in children can be difficult due to atypical presenting symptoms. While there are reported cases of acute appendicitis or appendiceal masses causing unilateral hydronephrosis, bilateral hydronephrosis as a complication of appendiceal mass is very rare. We report a case of a child who presented with cardinal symptomatology associated with the urogenital tract. Ultrasound (US) investigation showed a pelvic mass causing bilateral hydronephrosis. An initial diagnosis of a pelvic teratoma was made based on the US and computed tomography (CT) scan findings. The final diagnosis of an appendiceal mass causing bilateral hydronephrosis was established intraoperatively.
This fMRI study is about modelling the effective connectivity between Heschl's gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. MATERIALS #ENTITYSTARTX00026;
Dengue is the most important mosquito-borne viral disease. In the absence of specific drugs or vaccines, control focuses on suppressing the principal mosquito vector, Aedes aegypti, yet current methods have not proven adequate to control the disease. New methods are therefore urgently needed, for example genetics-based sterile-male-release methods. However, this requires that lab-reared, modified mosquitoes be able to survive and disperse adequately in the field.
Southeast Asian deforestation rates are among the world's highest and threaten to drive many forest-dependent species to extinction. Climate change is expected to interact with deforestation to amplify this risk. Here we examine whether regional incentives for sustainable forest management will be effective in improving threatened mammal conservation, in isolation and when combined with global climate change mitigation.
MeSH terms: Animals; Borneo; Climate*; Conservation of Natural Resources*; Gases/analysis*; Geography; Malaysia; Models, Biological; Nesting Behavior; Population Dynamics; Regression Analysis; Species Specificity; Trees/physiology*; Reproducibility of Results; Greenhouse Effect/prevention & control*; Ecosystem*; Pongo/physiology*
Burkholderia pseudomallei, a Gram-negative saprophytic bacterium, is the causative agent of the potentially fatal melioidosis disease in humans. In this study, environmental parameters including temperature, nutrient content, pH and the presence of glucose were shown to play a role in in vitro biofilm formation by 28 B. pseudomallei clinical isolates, including four isolates with large colony variants (LCVs) and small colony variants (SCVs) morphotypes. Enhanced biofilm formation was observed when the isolates were tested in LB medium, at 30 °C, at pH 7.2, and in the presence of as little as 2 mM glucose respectively. It was also shown that all SVCs displayed significantly greater capacity to form biofilms than the corresponding LCVs when cultured in LB at 37 °C. In addition, octanoyl-homoserine lactone (C(8)-HSL), a quorum sensing molecule, was identified by mass spectrometry analysis in bacterial isolates referred to as LCV CTH, LCV VIT, SCV TOM, SCV CTH, 1 and 3, and the presence of other AHL's with higher masses; decanoyl-homoserine lactone (C(10)-HSL) and dodecanoyl-homoserine lactone (C(12)-HSL) were also found in all tested strain in this study. Last but not least, we had successfully acquired two Bacillus sp. soil isolates, termed KW and SA respectively, which possessed strong AHLs degradation activity. Biofilm formation of B. pseudomallei isolates was significantly decreased after treated with culture supernatants of KW and SA strains, demonstrating that AHLs may play a role in B. pseudomallei biofilm formation.