One-pot synthesis of hydroxyapatite–silica nanopowder composite for hardness enhancement of glass ionomer cement (GIC)

Hydroxyapatite–silica nanopowder composite was prepared using one-pot sol–gel technique. The morphology of the powder consists of a mixture of spherical silica particles (～30 nm) embedded within the elongated hydroxyapatite (～103 nm). The synthesized nanoparticles were incorporated into commercial glass ionomer cement (GIC) and Vickers hardness was evaluated. Results shown that the addition of the nanopowder composite gave ～73% increment in the hardness compared to the pure GIC. Higher content of hydroxyapatite–silica nanopowder resulted in dense cement and produced a stronger GIC and the application of this material with improved hardness property might lead to extend the clinical indications, especially in stress bearing areas.     

PRODUCTION OF PALM OIL REFERENCE MATERIALS FOR THE DETERMINATION OF SOLID FAT CONTENT

ABSTRACT

Three palm oil reference materials were produced for solid fat content analysis employing the Malaysian Palm Oil Board (MPOB) Test Methods. Thirteen laboratories participated in the characterization study, where the solid fat content in palm oil, palm olein and palm stearin were identified at temperature range from 0 to 45C. The consensus values were calculated based on the acceptability of statistical results from collaborating laboratories. Both of the consensus values and their uncertainties (%) for each reference material are as follows: 71.12 ± 1.82% (0C), 54.07 ± 1.05% (10C), 37.44 ± 0.88% (15C), 24.18 ± 1.09% (20C), 13.32 ± 0.86% (25C), 7.64 ± 0.28% (30C), 4.05 ± 0.14% (35C) and 1.25 ± 0.49% (40C) for SFC of palm oil, 66.32 ± 1.93% (0C), 43.53 ± 1.32% (10C), 22.50 ± 0.78% (15C), 6.68 ± 1.14% (20C) and 1.40 ± 0.35% (25C) for SFC of palm olein, and 78.09 ± 1.23% (0C), 67.66 ± 0.71% (10C), 56.29 ± 1.18% (15C), 44.37 ± 1.13% (20C), 30.22 ± 1.25% (25C), 20.08 ± 0.58% (30C), 13.72 ± 0.32% (35C), 8.97 ± 0.72% (40C) and 5.06 ± 0.41% (45C) for solid fat content of palm stearin.

PRACTICAL APPLICATIONS

The implementation of the ISO 17025 accreditation should be encouraged for testing laboratories to assure the traceability of analysis performed. This accreditation requires the use of certified reference materials to ensure that the analysis performed is parallel to the ISO 17025 standards. However, the unavailability of palm oil reference materials will affect the implementation of such standards for laboratories that are performing palm oil analyses. Hence, this study is aimed to characterize and certify the palm oil reference materials for determination of solid fat content. The establishment of this study is hoped to increase the credibility of laboratories, which are involved in the palm oil analysis. This will also promote the Malaysia Palm Oil Board as a center for the certification of palm oil reference materials.     

Investigation of superhalogen behaviour of RuF n (n = 1–7) clusters: density functional theory (DFT) study

In the present investigation, interaction of ruthenium (Ru) atoms with fluorine (F) atoms was studied using the density functional theory utilizing B3LYP method. It was found that up to seven F atoms can bind to a single Ru atom which results in increase of electron affinities successively, reaching a peak value of 6·95 eV for RuF₆. Its stability and reactivity were also examined by using HOMO–LUMO gap, molecular orbital analysis and binding energy of these clusters. It is found that energy required for dissociation of F₂ molecules are higher than energy required for dissociation of F atoms. The unusual properties are attributed to the involvement of inner shell 4d-electrons, which not only allow RuF _n clusters to belong to the class of superhalogens but also show that its valence can exceed the nominal value of 1. The interaction of RuF₄ superhalogen with an alkali atom lithium (Li) were also studied which suggests that a new class of salt can be synthesized by reacting RuF₄ with Li.     

A NEW APPROACH TO PERFORMANCE ANALYSIS OF CHOPPER CONTROLLED D.C. MOTOR DRIVE

ABSTRACT

An analytical method for performance analysis of a d.c. separately excited motor fed from a chopper is presented. The motor input voltage is represented as a series of step-voltages with a time phase difference. The system equations are solved to obtain closed-form solutions for motor current and speed, for transient as well as steady state conditions. The method presented is superior to existing methods in that the solution is in closed-form, and does not make recourse to recursive numerical techniques. The solutions for steady state condition corresponding to any set of operating conditions (voltage, chopper duty factor, load torque) can be directly obtained. The computational effort and time needed is therefore extremely small as compared to other methods.     

0-1 Quadratic programming approach for optimum solutions of two scheduling problems

Two scheduling problems are considered: (1) scheduling n jobs non-preemptively on a single machine to minimize total weighted earliness and tardiness (WET); (2) scheduling n jobs non-preemptively on two parallel identical processors to minimize weighted mean flow time. In the second problem, a pre-ordering of the jobs is assumed that must be satisfied for any set of jobs scheduled on each specific machine. Both problems are known to be NP-complete. A 0-1 quadratic assignment formulation of the problems is presented. An equivalent 0-1 mixed integer linear programming approach for the problems are considered and a numerical example is given. The formulations presented enable one to use optimal and heuristic available algorithms of 0-1 quadratic assignment for the problems considered here.     

A Novell Backstepping Nonlinear Controller Design for Nonlinear Vibration Systems

Introducing basic design methodology for developing backstepping nonlinear controller for vibration control system. With a simplified second-order system model of nonlinear vibration system (Duffing’s equation), where, the process has illustrated the backstepping design step-by-step. Backstepping is a novel nonlinear design tool, which is based on constructing the Lyapunov function for the closed-loop systems and guarantees the stability and tracking performance through energy dissipation. In general, this ...     

Intraoperative dialysis during liver transplantation with citrate dialysate

Liver transplantation for acutely ill patients with fulminant liver failure carries high intraoperative and immediate postoperative risks. These are increased with the presence of concomitant acute kidney injury (AKI) and intraoperative dialysis is sometimes required to allow the transplant to proceed. The derangements in the procoagulant and anticoagulant pathways during fulminant liver failure can lead to difficulties with anticoagulation during dialysis, especially when continued in the operating room. Systemic anticoagulation is unsafe and regional citrate anticoagulation in the absence of a functional liver carries the risk of citrate toxicity. Citrate dialysate, a new dialysate with citric acid can be used for anticoagulation in patients who cannot tolerate heparin or regional citrate. We report a case of a 40-year-old female with acetaminophen-induced fulminant liver failure with associated AKI who underwent intraoperative dialytic support during liver transplantation anticoagulated with citrate dialysate during the entire procedure. The patient tolerated the procedure well without any signs of citrate toxicity and maintained adequate anticoagulation for patency of the dialysis circuit. Citrate dialysate is a safe alternative for intradialytic support of liver transplantation in fulminant liver failure.     

Proteome-wide screening for the analysis of protein targeting of <i>Chlamydia pneumoniae</i> in endoplasmic reticulum of host cells and their possible implication in lung cancer development

Available reports have confirmed a link between bacterial infection and the progression of different types of cancers, including colon, lungs, and prostate cancer. Here we report the Chlamydia pneumonia proteins targeting in endoplasmic reticulum (ER) using in-silico approaches and their possible role in lung cancer etiology. We predicted 48 proteins that target human ER, which may be associated with protein folding and protein-protein interactions during infection. The results showed C. pneumoniae proteins targeting human ER and their implications in lung cancer growth. These targeted proteins may be involved in competitive interactions between host and bacterial proteins, which may change the usual pathway functions and trigger the development of lung cancer. Moreover, C. pneumoniae unfolded protein accumulation in the human ER possibly induces ER stress, consequently activating the unfolded protein response (UPR), and providing a favorable microenvironment for cancer growth. The current study showed the C. pneumoniae protein targeting in ER of host cell and their implication in lung cancer growth. These results may help researchers better manage lung cancer and establish a molecular mechanism for C. pneumoniae lung cancer association.     

The effect of positive/negative ion on the dust grain charging process in a Vasyliunas-Cairns (VC)-distributed dusty plasma system

Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting results. In this paper, we consider a low-temperature non- equilibrium multispecies plasma model, which consists of Vasyliunas–Cairns (VC) distributed electrons, negative/positive streaming ions, and negatively-charged dust grains to explain the charging mechanism of dust grains. The main theme of this work is to derive expressions of currents for negatively-charged dust grains (considering an equilibrium state position) in the plasma environment comprised of electrons and positive/negative streaming ions using the VC distribution function. Our proposed model shows that the dust grain surface potential is significantly affected by different plasma parameters such as the negative ion streaming velocity (S_n), positive ion streaming velocity (S_i), spectral indices of VC distribution, negative ion charging state (Z_n), positive ion charging state (Z_i), and negative ion number density (ρ).