Using durian rind as bridging material to overcome fluid loss and lost circulation problems in drilling operations

Lost circulation is one of the drilling operational problems. It refers to the total or partial loss of drilling fluid into highly permeable zones or natural or induced fractures. This problem is likely to occur when the hydrostatic head pressure of drilling fluid in the hole exceeds the formation pressure. Today, managing lost circulation remains a significant challenge to oilwell drilling operations because it may contribute to high non-productive time. It is imperative to note that the overbalance pressure situation also can cause the invasion of mud filtrate into production zones which will result in formation damage. To address these problems, an experimental investigation has been done on durian rind as an alternative fluid loss and lost circulation materials in water-based mud. Durian rind was selected as a mud loss control material because it contains close to 20% pectin which may complement the formation of high quality mat-like bridges across openings of the formation. The test involved the use of standard mud testing equipment and a lost circulation test cell. Durian rind powder was prepared by cleaning and cutting the durian rind into small pieces of 1 to 2 cm, and then dried them in an oven at 60°C for 48 hours before grinding into five different sizes from coarse to ultra-fine while Hydro-plug, the commercial lost circulation material was supplied by Scomi Energy. The fluid loss test was conducted using a standard low pressure filter press while the bridging test was carried out at 100 psi of pressure difference and ambient temperature using a lost circulation cell. Fine durian in the water-based mud gave the best fluid loss control compared to coarse durian rind, fine and coarse Hydro-plug. The experimental results also showed that at 15 lb/bbl (42.8 kg/m3) optimum concentration, coarse and intermediate durian rind have outperformed Hydro-plug by showing an excellent control of mud losses in 1 and 2 mm simulated fractures

Correlation of antiangiogenic, antioxidant and cytotoxic activities of some Sudanese medicinal plants with phenolic and flavonoid contents

Background: Consumption of medicinal plants to overcome diseases is traditionally belongs to the characteristics of most cultures on this earth. Sudan has been a host and cradle to various ancient civilizations and developed a vast knowledge on traditional medicinal plants. The present study was undertaken to evaluate the antioxidant, antiangiogenic and cytotoxic activities of six Sudanese medicinal plants which have been traditionally used to treat neoplasia. Further the biological activities were correlated with phytochemical contents of the plant extracts. Methods: Different parts of the plants were subjected to sequential extraction method. Cytotoxicity of the extracts was determined by dimethylthiazol-2-yl)- 2,5diphenyl tetrazolium bromide (MTT) assay on 2 human cancer (colon and breast) and normal (endothelial and colon fibroblast) cells. Anti-angiogenic potential was tested using ex vivo rat aortic ring assay. DPPH (1,1-diphenyl-2-picrylhydrazyl) assay was conducted to screen the antioxidant capabilities of the extracts. Finally, total phenolic and flavonoid contents were estimated in the extracts using colorimetric assays. Results: The results indicated that out of 6 plants tested, 4 plants (Nicotiana glauca, Tephrosia apollinea, Combretum hartmannianum and Tamarix nilotica) exhibited remarkable anti-angiogenic activity by inhibiting the sprouting of microvessels more than 60%. However, the most potent antiangiogenic effect was recorded by ethanol extract of T. apollinea (94.62%). In addition, the plants exhibited significant antiproliferative effects against human breast (MCF-7) and colon (HCT 116) cancer cells while being non-cytotoxic to the tested normal cells. The IC₅₀ values determined for C. hartmannianum, N. gluaca and T. apollinea against MCF-7 cells were 8.48, 10.78 and 29.36 μg/ml, respectively. Whereas, the IC50 values estimated for N. gluaca, T. apollinea and C. hartmannianum against HCT 116 cells were 5.4, 20.2 and 27.2 μg/ml, respectively. These results were more or less equal to the standard reference drugs, tamoxifen (IC₅₀ = 6.67 μg/ml) and 5-fluorouracil (IC₅₀ = 3.9 μg/ml) tested against MCF-7 and HCT 116, respectively. Extracts of C. hartmannianum bark and N. glauca leaves demonstrated potent antioxidant effect with IC₅ₒs range from 9.4-22.4 and 13.4-30 μg/ml, respectively. Extracts of N. glauca leaves and T apollinea aerial parts demonstrated high amount of flavonoids range from 57.6-88.1 and 10.7-78 mg quercetin equivalent/g, respectively. Conclusions: These results are in good agreement with the ethnobotanical uses of the plants (N. glauca, T. apollinea, C. hartmannianum and T. nilotica) to cure the oxidative stress and paraneoplastic symptoms caused by the cancer. These findings endorse further investigations on these plants to determine the active principles and their mode of action.Loiy Elsir A Hassan, Mohamed B Khadeer Ahamed, Aman S Abdul Majid, Hussein M Baharetha, Nahdzatul S Muslim, Zeyad D Nassar, and Amin MS Abdul Maji

Karakteristik dan Pembentukan Batuan Beku di Pegunungan Jiwo, Bayat, Jawa Tengah

Pegunungan Jiwo, Bayat merupakan salah satu dari tiga wilayah di Jawa yang memperlihatkan adanya singkapan batuan-batuan metamorf yang berumur Pra-Tersier. Di atas batuan-batuan metamorf tersebut diendapkan tidak selaras batuan-batuan sedimen Tersier yang termasuk kedalam Formasi Wungkal-Gamping. Batuan-batuan metamorf maupun sedimen pada beberapa tempat diterobos oleh batuan-batuan beku diantaranya adalah gabro, diabas, basalt, dan diorite. Keberadaan batuan-batuan beku tersebut menjadi menarik karena sedikit terpisah dari jalur magmatic Pegunungan Selatan Jawa Timur. Batuan-batuan beku hasil kegiatan magmatisme tesebut di atas, hadir sebagai batuan beku plutonik (gabro, gabro mikro atau diabas, diorit), dan batuan beku vulkanik (basalt), yang hadir baik  sebai intrusi (retas) maupun lava. Sebagian besar batuan beku tersebut di permukaan dalam keadan lapuk, dan hanya sebagian kecil singkapan yang memperlihatkan keadaan yang fres atau segar, diantaranya pada beberapa inti batuan beku yang mengalamai pelapukan mengulit bawang (spheroidal weathering). Kenampakan mikroskopik, gabro dan gabro mikro umumnya memperlihatkan tekstur equigranular, kumulus, ofitik, subofitik, dan diabasik disusun oleh mineral-mineral primer plagioklas (±52-66%), Olivin (±0-14%), piroksen (±4-18%), mineral opak, baik kemungkinan primer maupun sekunder (±2-12%). Sebagian besar  gabro mengalami ubahan hidrotermal lemah-sedang, yang dicirikan oleh terubahnya beberapa mineral primer menjadi mineral-mineral klorit, silica, epidot, karbonat, serpentin,dan aktinolit. Basalt secara mikroskopik, memperlihatkan tekstur inequigranular, porfiritik-porfiroafanitik, disusun oleh mineral-mineral primer plagioklas, olivin, piroksen, mineral opak, baik kemungkinan primer maupun sekunder  dengan mineral sekunder seperti klorit dan  karbonat . Batuan-batuan beku di Pegunungan Jiwo tersebut, diperkirakan merupakan hasil magmatisme yang berumur Eosen Akhir-Miosen Awal (39,82±1,49 Ma sampai  13.852±5.45 juta tahun)  dan merupakan bagian dari busur kepulauan Sunda-Banda. Magmatisme tersebut disebabkan oleh adanya subduksi kearah utara lempeng Hindia-Australia di bawah bagian tenggara lempeng Eurasia yang dikenal sebagai Sundaland

The Mediating Effect of Job Satisfaction on Employee Loyalty: A Case Study of a Developer Company in Malaysia

Employees’ loyalty is being described as the ability of the employee or staff members of the organization to stay and contribute well in their jobs for such a long term. In the recent years, resignation of employees did show an increment in many companies in Malaysia. This research specifically study on a developer company which is one of the constructions developers company in Johor, Malaysia The purpose of this study is to investigate the factors of training, rewards and benefits and working condition as determinants toward employee loyalty and how job satisfaction mediate the relationship between independent variables and dependent variables as the factors that influence the employee loyalty in organizations. A stratified sampling method was adopted as the sampling method and questionnaires is chosen as the research instrument adopted previous researcher and adopt it into this research. Respondents of this research consists of 155 respondents who are employees of the developer company. In general, we conclude that employee loyalty in the developer company has positive relation between the working condition, rewards and benefits, training and job satisfaction and confirms the partial mediation of Job Satisfaction between the independent variables, rewards/benefits and training with employee loyalty.     Keywords: Employee Satisfaction, Employee Loyalty, Working Condition, Training, Malaysi

Temperature and strain feedback control for shape memory alloy actuated composite plate

There are several input variables that can be used to control the deflection of a shape memory alloy (SMA) composite system such as the resistance or temperature of the SMA actuator and position or strain of the composite plate. It is common to control the actuator directly, however SMA is nonlinear and it exhibits hysteresis which may result in inaccurate control of the plate’s deflection. Thus controlling the plate’s deflection may be more effective by using input measurement from the composite plate. The aim of this study is to propose the optimal feedback variable deflection control of a fiberglass composite plate system using SMA actuators. Two types of variables were investigated which were temperature of the SMA actuator and strain of the composite plate. The feedback control system for SMA actuated composite plate was implemented with different types of sensors; thermocouple and strain gauge. When current is supplied to the SMA actuator, it will contract and produce a force that will deflect the composite plate. During this process, the SMA actuator’s temperature changes with the current supplied and the strain of the composite plate changes during deflection due to torsion and bending. Thus, it is proposed to use these variables as the input to the feedback of the smart composite plate system to control the movement of the plate. Using the adopted control technique of the experimental test bench presented here, the strain feedback system was more effective and energy efficient compared to the temperature feedback for the control of morphing composite plate

Ergogenic, anti-diabetic and antioxidant attributes of selected Malaysian herbs: characterisation of flavonoids and correlation of functional activities

In the present work, aqueous ethanolic (60% ethanol) extracts from selected Malaysian herbs including Murraya koenigii L. Spreng, Lawsonia inermis L., Cosmos caudatus Kunth, Piper betle L., and P. sarmentosum Roxb. were evaluated for their ergogenic, anti-diabetic and antioxidant potentials. Results showed that the analysed herbs had ergogenic property and were able to activate 5'AMP-activated protein kinase (AMPK) in a concentration dependant manner. The highest AMPK activation was exhibited by M. koenigii extract which showed no significant (p > 0.05) difference with green tea (positive control). For anti-diabetic potential, the highest α-glucosidase inhibition was exhibited by M. koenigii extract with IC50 of 43.35 ± 7.5 μg/mL, which was higher than acarbose (positive control). The determinations of free radical scavenging activity and total phenolics content (TPC) indicated that the analysed herbs had good antioxidant activity. However, C. caudatus extract showed superior antioxidant activity with IC50 against free radical and TPC of 21.12 ± 3.20 μg/mL and 221.61 ± 7.49 mg GAE/g, respectively. RP-HPLC analysis established the presence of flavonoids in the herbs wherein L. inermis contained the highest flavonoid (catechin, epicatechin, naringin and rutin) content (668.87 mg/kg of extract). Correlations between the analyses were conducted, and revealed incoherent trends. Overall, M. koenigii was noted to be the most potent herb for enhancement of AMPK activity and α-glucosidase inhibition but exhibited moderate antioxidant activity. These results revealed that the selected herbs could be potential sources of natural ergogenic and anti-diabetic/antioxidant agents due to their rich profile of phenolics. Further analysis in vivo should be carried out to further elucidate the mechanism of actions of these herbs as ergogenic aids and anti-diabetic/antioxidant agents

Evaluation of the diuretic potentials of naringenin in hypercholesterolemic rats

Purpose: To investigate the diuretic potentials of naringenin (NGN) in obesity induced in rats by high fat diet (HFD).Methods: To prepare HFD, normal pellet diet was crushed and thoroughly mixed with cholesterol powder (1 % w/w). The mixture was mixed with some water and made into pellets which were then oven-baked to dry. Four groups of male Wistar albino rats (n = 6) were used for the study. Normal control (group I) received normal pellet diet. Group 2 (HFD-only) was fed HFD for 28 days, while Groups 3 and 4 were co-administered HFD and NGN at doses of 50 and 100 mg/kg, respectively. All treatments were given orally, and lasted for 28 days. Twenty-four hours after the last dose of NGN, blood was collected from all rats and total cholesterol levels determined to confirm obesity. Thereafter, the rats were placed in metabolic cages and urine samples were collected at two time-points (5 and 24 h) for measurement of urine volume, urinary pH, conductivity and electrolyte levels (Na, K and Cl).Results: Treatment with HFD resulted in significantly (p < 0.05) increased serum cholesterol level (178.83 ± 5.43 mg/dL) when compared to normal control rats (88.17 ± 4.04 mg/dL). It also led to decrease in urinary volume (~50 %) at both time points (5 and 24 h) and in excretion of urinary electrolytes (sodium, potassium and chloride ions). However, the changes in these parameters were significantly reversed by NGN administration (p < 0.05).Conclusion: These results demonstrate the diuretic activity of NGN in HFD-induced obese rats. Thus, NGN can be further explored for use in combination with hypolipidemic agents to tackle obesity.Keywords: High-fat diet, Hypercholesterolemia, Naringenin, Obesit

Altered cellular infiltration and cytokine levels during early Mycobacterium tuberculosis sigC mutant infection are associated with late-stage disease attenuation and milder immunopathology in mice

<p>Abstract</p> <p>Background</p> <p>Mouse virulence assessments of certain <it>Mycobacterium tuberculosis </it>mutants have revealed an immunopathology defect in which high tissue CFU counts are observed but the tissue pathology and lethality are reduced. <it>M. tuberculosis </it>mutants which grow and persist in the mouse lungs, but have attenuated disease progression, have the immunopathology (<it>imp</it>) phenotype. The antigenic properties of these strains may alter the progression of disease due to a reduction in host immune cell recruitment to the lungs resulting in disease attenuation and prolonged host survival.</p> <p>Results</p> <p>In this study we focused on the mouse immune response to one such mutant; the <it>M. tuberculosis </it>Δ<it>sigC </it>mutant. Aerosol infection of DBA/2 and SCID mice with the <it>M. tuberculosis </it>Δ<it>sigC </it>mutant, complemented mutant and wild type strain showed proliferation of mutant bacilli in mouse lungs, but with decreased inflammation and mortality in DBA/2 mice. SCID mice shared the same phenotype as the DBA/2 mice in response to the Δ<it>sigC </it>mutant, however, they succumbed to the infection faster. Bronchoalveolar lavage (BAL) fluid analysis revealed elevated numbers of infiltrating neutrophils in the lungs of mice infected with wild type and complemented Δ<it>sigC </it>mutant strains but not in mice infected with the Δ<it>sigC </it>mutant. In addition, DBA/2 mice infected with the Δ<it>sigC </it>mutant had reduced levels of TNF-α, IL-1β, IL-6 and IFN-γ in the lungs. Similarly, there was a reduction in proinflammatory cytokines in the lungs of SCID mice. In contrast to the mouse model, the Δ<it>sigC </it>mutant had reduced initial growth in guinea pig lungs. A possible mechanism of attenuation in the Δ<it>sigC </it>mutant may be a reduction in neutrophilic-influx in the alveolar spaces of the lungs, and decreased proinflammatory cytokine secretion. In contrast to mouse data, the <it>M. tuberculosis </it>Δ<it>sigC </it>mutant proliferates slowly in guinea pig lungs, a setting characterized by caseating necrosis.</p> <p>Conclusion</p> <p>Our observations suggest that the immunopathology phenotype is associated with the inability to trigger a strong early immune response, resulting in disease attenuation. While macrophages and T cells have been shown to be important in containing <it>M. tuberculosis </it>disease our study has shown that neutrophils may also play an important role in the containment of this organism.</p

Modelling and PID value search for antilock braking system (ABS) of a passenger vehicle

This paper presents the methodologies use in determining the PID value of an Antilock Brake System (ABS) of a Malaysian made passenger vehicle. The research work involves experimental work for data acquisitions, development of braking model, parameter tuning for both simulation model parameter and PID values search. A Malaysian made car is equipped with instrumentation used to collect vehicle behaviour during normal and hard braking manoeuvres. The data collected are the vehicle’s stopping distance and longitudinal speed. The data during the normal braking are used to validate a two degree of freedom (2 DOF) of vehicle’s braking model, while the data collected during the hard braking are used to search for the PID value used to control the operation of the ABS system. The developed simulation model of a braking system correlates well with the experimental data and the tuning done on the PID algorithm indicates that the ABS is controlled by the PI system