Colloidal behavior of aqueous montmorillonite suspensions in the presence of non-ionic polymer

In this paper we characterized at first, the rheological behavior of the bentonite suspensions and the aqueous solutions of polyethylene oxide (PEO), then we were investigated the influence of this polymer in a water-based drilling fluid model (6% of bentonite suspension). The objective is to exhibit how the non ionic polymer with molecular weight 6×103 g/mol. of varying concentration mass (0.7%, 1%, 2% et 3%) significantly alter the rheological properties (yield stress, viscosity, loss and elastic modulus) of the bentonite suspensions. The rheological measurements made in simple shear and in dynamic on the mixture (water-bentonite-PEO), showed rheological properties of bentonite suspensions both in the presence and absence of non-ionic polymer. The PEO presents an affinity for the bentonite particles slowing down their kinetic aggregation. The analysis by X-rays diffraction also allowed understanding the structure of this mixture. It had revealed the intercalation between of the clay platelets on one hand, and the links bridges assured by the chains of polymer between bentonite particles beyond a critical concentration in PEO on the other hand. The Herschel- Bulkley rheological model is used for the correlation of our experimental result

The Personalization of Clopidogrel Antiplatelet Therapy: The Role of Integrative Pharmacogenetics and Pharmacometabolomics

Dual antiplatelet therapy of aspirin and clopidogrel is pivotal for patients undergoing percutaneous coronary intervention. However, the variable platelets reactivity response to clopidogrel may lead to outcome failure and recurrence of cardiovascular events. Although many genetic and nongenetic factors are known, great portion of clopidogrel variable platelets reactivity remain unexplained which challenges the personalization of clopidogrel therapy. Current methods for clopidogrel personalization include CYP2C19 genotyping, pharmacokinetics, and platelets function testing. However, these methods lack precise prediction of clopidogrel outcome, often leading to insufficient prediction. Pharmacometabolomics which is an approach to identify novel biomarkers of drug response or toxicity in biofluids has been investigated to predict drug response. The advantage of pharmacometabolomics is that it does not only predict the response but also provide extensive information on the metabolic pathways implicated with the response. Integrating pharmacogenetics with pharmacometabolomics can give insight on unknown genetic and nongenetic factors associated with the response.This review aimed to review the literature on factors associated with the variable platelets reactivity response to clopidogrel, as well as appraising current methods for the personalization of clopidogrel therapy. We also aimed to review the literature on using pharmacometabolomics approach to predict drug response, as well as discussing the plausibility of using it to predict clopidogrel outcome

Pengaruh Pemberian Ekstrak Tinta Cumi (Squid Ink) Terhadap Aterosklerosis

Squid ink consists of DHI, DHICA, and 2-carboxyl indole that improve lipid profile and remove foam cells in blood vessel walls. This study was aimed to analyze the effect of squid ink on atherosclerosis-induced Wistar rats. This was an experimental study. We used randomized controlled trial with pre-post test design for lipid profile assessment and randomized post-test only control design for blood vessel evaluation (foam cells in layers of coronary artery). Samples were 27 Wistar rats, divided into three groups; all were atherosclerosis-induced with initial injection of 0.006mg iv adrenalin on day 1, followed by standard diet and egg yolk until day 30. Squid ink extract was given to group P1 and P2 on days 15-30 in different doses, but not to control group. Data were analyzed by using Saphiro-Wilk test and paired t-test. The results showed that P2 group had decreased means of total cholesterol (-33.62 mg/dl), triglyceride (-28.00 mg/dl), and LDL cholesterol (-28.16 mg/dl), but an increased mean of HDL cholesterol (11.60 mg/dl). There were decreased numbers of foam cells in the layers of coronary arteries of P1 and P2 group compared to the control group. Conclusion: Squid ink extract could lower total cholesterol, triglyceride, and LDL cholesterol levels, and increase HDL cholesterol level. Moreover, it could remove foam cells from the layers of coronary arteries.Keywords: squid ink, atherosclerosis, lipid profile, foam cells Asbtrak: Tinta cumi memiliki kandungan DHI, DHICA, dan 2-carboxyl indole yang dapat memperbaiki profil lipid dan mengurangi sel busa pembuluh darah. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian ekstrak tinta cumi terhadap tikus yang diinduksi aterosklerosis. Jenis penelitian ialah eksperimental dengan randomized controlled with pre-post test design untuk penilaian profil lipid dan post test only design untuk penilaian pembuluh darah (sel busa dalam dinding arteri koronaria). Sampel terdiri dari 27 tikus Wistar jantan, dibagi secara random menjadi tiga kelompok; kesemuanya diberi induksi aterosklerosis dengan injeksi inisial adrenalin 0,006 mg iv pada hari ke-1, dilanjutkan diet standar dan diet kuning telur sampai hari ke-30. Tikus kelompok kontrol tidak diberikan ekstrak tinta cumi; tikus kelompok perlakuan 1 dan perlakuan 2 diberikan tambahan ekstrak tinta cumi pada hari ke 16 sampai hari ke 30 dengan dosis yang berbeda. Analisis data dengan uji Saphiro-Wilk dan uji paired t-test. Hasil penelitian memperlihatkan penurunan rerata setelah perlakuan pada kelompok P2 ialah kolesterol total (-33,62 mg/dl), trigliserida (-28,00 mg/dl), dan kolesterol LDL (-28,16 mg/dl), serta peningkatan rerata kolesterol HDL (11,60 mg/dl). Terdapat penurunan jumlah sel busa kelompok perlakuan P1 dan P2 dibandingkan kelompok kontrol. Simpulan: Pemberian ekstrak tinta cumi menurunkan kadar kolesterol total, trigliserida dan kolesterol LDL, meningkatkan kadar kolesterol HDL, serta menurunkan jumlah sel busa dalam dinding arteri koronaria

Loss of UGP2 in brain leads to a severe epileptic encephalopathy, emphasizing that bi-allelic isoform-specific start-loss mutations of essential genes can cause genetic diseases.

Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders, resulting in early-onset, therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy, severe developmental delay, progressive microcephaly, visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent, homozygous variant (chr2:64083454A > G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform, which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells, leading to altered glycogen metabolism, upregulated unfolded protein response and premature neuronal differentiation, as modeled during pluripotent stem cell differentiation in vitro. In contrast, the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly, it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease, even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies

Simple control scheme buck-boost DC-DC converter for stand alone PV application system

In this paper a buck-boost dc-dc converter for pv application is proposed, which is mainly composed of a buck – boost converter, PV panel, load and a battery. Existing dc-dc converter can convert the power from the PV panel, but unfortunately the PV panel can only provide power when there is a high intensity of light. In order to provide power supply to the load without any interruption, buck-boost dc-dc converter is introduced. The power intermittency issue of PV panel can be overcome with the aid of a secondary supply which is in this case, the batter. The integration system between the primary and the secondary supply is controlled by a simple proposed control scheme. Battery act as a power in the low voltage side while PV panel is taking over in the high voltage side. Buck-boost converter is operated either is buck or boost mode according to the performance of the PV panel. This paper is presented the simple control scheme to decide the mode suitable for the buck and boost mode. Various conditions are simulated to verify the working operation of the buck-boost converter and to representing solar panel in real life. Simulation and experimental are carried out to verify the system

A New Optimal DTC Switching Strategy for Open-End Windings Induction Machine using Dual Inverter

Since the early 1980s, fast torque dynamic control has been a subject of research in AC drives. To achieve superior torque dynamic control, two major techniques are used, namely Field Oriented Control (FOC) and Direct Torque Control (DTC), spurred on by rapid advances in embedded computing systems. Both approaches employ the space vector modulation (SVM) technique to perform the voltage source inverter into over modulation region for producing the fastest torque dynamic response. However, the motor current tends to increase beyond its limit (which can damage the power switches) during the torque dynamic condition, due to inappropriate flux level (i.e. at rated stator flux). Moreover, the torque dynamic response will be slower, particularly at high speed operations since the increase of stator flux will produce negative torque slopes more often. The proposed research aims to formulate an optimal switching modulator and produce the fastest torque dynamic response. In formulating the optimal switching modulator, the effects of selecting different voltage vectors on torque dynamic responses will be investigated. With greater number of voltage vectors offered in dual inverters, the identification of the most optimal voltage vectors for producing the fastest torque dynamic responses will be carried out based on the investigation. The main benefit of the proposed strategy is that it provides superior fast torque dynamic response which is the main requirements for many AC drive applications, e.g. traction drives, electric transportations and vehicles

NUMERICAL EXPERIMENT ON EFFECT OF SURFACE ROUGHNESS FOR HEAT AND FLOW AROUND TWO CONTACTING PARTICLES

The aim of the present work is to establish a model of heat transfer between particles by using the numerical simulation that can be incorporated in the discrete element method (DEM). The contact heat transfer between particles can be regarded as a contact thermal resistance problem. In the thermal resistance model, the local characteristics, e.g. exact contact area and heat flux distribution on particle surface, are important. However, it is difficult to measure such factors in detail. Accordingly, the authors utilized a numerical simulation. The thermal resistance was modeled by placing a small solid block between the contacting areas in the simulation. The small solid thickness represents the surface roughness and the width represents the contact force. The simulated temperature profile along the center line through two particle’s centers well agreed with measured one

Self-tuning Fuzzy Logic Controller Based on Takagi-Sugeno Applied to Induction Motor Drives

Fuzzy logic controller has been the main focus for many researchers and industries in motor drives. The popularity of Fuzzy Logic Controller (FLC) is due to its reliability and ability to handle parameters changes during load or disturbance. Fuzzy logic design can be visualized in two categories, mamdani design or Takagi-Sugeno (TS). Mamdani type can facilitate the design process, however it require high computational burden especially with big number of rules and experimental testing. This paper, develop Self-Tuning (ST) mechanism based on Takagi-Sugeno (TS) fuzzy type. The mechanism tunes the input scaling factor of speed fuzzy control of Induction Motor (IM) drives Based on the speed error and changes of error. A comparison study is done between the standard TS and the ST-TS based on simulations approaches considering different speed operations. Speed response characteristics such as rise time, overshoot, and settling time are compared for ST-TS and TS. It was shown that ST-TS has optimum results compared to the standard TS. The significance of the proposed method is that, optimum computational burden reduction is achieved