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Fulltext A Robust and Fast Computation Touchless Palm Print Recognition System Using LHEAT and the IFkNCN Classifier

Jaafar H, Ibrahim S, Ramli DA

Comput Intell Neurosci, 2015;2015:360217.
PMID: 26113861 DOI: 10.1155/2015/360217

Mobile implementation is a current trend in biometric design. This paper proposes a new approach to palm print recognition, in which smart phones are used to capture palm print images at a distance. A touchless system was developed because of public demand for privacy and sanitation. Robust hand tracking, image enhancement, and fast computation processing algorithms are required for effective touchless and mobile-based recognition. In this project, hand tracking and the region of interest (ROI) extraction method were discussed. A sliding neighborhood operation with local histogram equalization, followed by a local adaptive thresholding or LHEAT approach, was proposed in the image enhancement stage to manage low-quality palm print images. To accelerate the recognition process, a new classifier, improved fuzzy-based k nearest centroid neighbor (IFkNCN), was implemented. By removing outliers and reducing the amount of training data, this classifier exhibited faster computation. Our experimental results demonstrate that a touchless palm print system using LHEAT and IFkNCN achieves a promising recognition rate of 98.64%.
A case of a hand burns associated with a "wrap-around" pulse oximeter in an infant

Hisham A, Hafizuddin Bin Salleh M, Ibrahim S, Mohd Yussof SJ

Int Wound J, 2020 Aug;17(4):1097-1098.
PMID: 32333718 DOI: 10.1111/iwj.13375
A comparative fluid flow characterisation in a low frequency/high power sonoreactor and mechanical stirred vessel

Sajjadi B, Raman AA, Ibrahim S

Ultrason Sonochem, 2015 Nov;27:359-73.
PMID: 26186855 DOI: 10.1016/j.ultsonch.2015.04.034

This study aims at analysing the jet-like acoustic streaming generated under low-frequency and high-power ultrasound irradiation and comparing it with fluid streaming generated by traditional mechanical mixing. The main characteristics of fluid flow, which include radial, axial and tangential terms of velocity and their effects on fluid flow pattern, pressure distribution, axial mixing time and turbulence intensity were considered at different power inputs. Both 3D CFD simulation and Particle Image Velocimetry (PIV) were used in this study. The CFD results indicated that the jet-like acoustic streaming reached the velocity magnitude of 145 cm/s at 400 W, which reduced the mixing time to 1.38 s. However, the minimum mixing time of 3.18 s corresponding to the impeller rotational speed of 800 RPM was observed for mechanical stirring. A uniform axial flow pattern was generated under ultrasound irradiation whereas the tangential flow pattern was more prominent in the stirred vessel. Besides, the highest turbulence was observed in the vicinity of the ultrasound transducer and impeller with the values of 138% and 82% for the ultrasonicator and stirred vessel, respectively. The predicted fluid flow pattern under ultrasound irradiation was in a reasonable agreement with that obtained from PIV, with a reasonable accuracy.
Fulltext A preliminary appraisal of the effect of pumping on seawater intrusion and upconing in a small tropical island using 2D resistivity technique

Kura NU, Ramli MF, Ibrahim S, Sulaiman WN, Zaudi MA, Aris AZ

ScientificWorldJournal, 2014;2014:796425.
PMID: 25574493 DOI: 10.1155/2014/796425

The existing knowledge regarding seawater intrusion and particularly upconing, in which both problems are linked to pumping, entirely relies on theoretical assumptions. Therefore, in this paper, an attempt is made to capture the effects of pumping on seawater intrusion and upconing using 2D resistivity measurement. For this work, two positions, one perpendicular and the other parallel to the sea, were chosen as profile line for resistivity measurement in the coastal area near the pumping wells of Kapas Island, Malaysia. Subsequently, water was pumped out of two pumping wells simultaneously for about five straight hours. Then, immediately after the pumping stopped, resistivity measurements were taken along the two stationed profile lines. This was followed by additional measurements after four and eight hours. The results showed an upconing with low resistivity of about 1-10 Ωm just beneath the pumping well along the first profile line that was taken just after the pumping stopped. The resistivity image also shows an intrusion of saline water (water enriched with diluted salt) from the sea coming towards the pumping well with resistivity values ranging between 10 and 25 Ωm. The subsequent measurements show the recovery of freshwater in the aquifer and how the saline water is gradually diluted or pushed out of the aquifer. Similarly the line parallel to the sea (L2) reveals almost the same result as the first line. However, in the second and third measurements, there were some significant variations which were contrary to the expectation that the freshwater may completely flush out the saline water from the aquifer. These two time series lines show that as the areas with the lowest resistivity (1 Ωm) shrink with time, the low resistivity (10 Ωm) tends to take over almost the entire area implying that the freshwater-saltwater equilibrium zone has already been altered. These results have clearly enhanced our current understanding and add more scientific weight to the theoretical assumptions on the effects of pumping on seawater intrusion and upconing.
A rare case of diplopodia and syndactyly: anatomical and surgical considerations

Kadir KH, Abdul Rashid AH, Das S, Ibrahim S

J Foot Ankle Surg, 2011 Mar-Apr;50(2):252-6.
PMID: 21354013 DOI: 10.1053/j.jfas.2010.10.017

Diplopodia is a rare congenital disorder that has not been extensively discussed in textbooks, and case reports appear to be the main source of information. Although the exact cause of diplopodia remains unknown, the presence of extra digits as well as metatarsals and tarsals allows it to be differentiated from pedal polydactyly. Syndactyly refers to the congenital fusion of the digits. Concomitant bilateral syndactyly and diplopodia is extremely unusual, and in this report we describe a case of right diplopodia and left polydactyly combined with bilateral manual syndactyly in a 15-year-old girl who was ultimately treated with through-the-knee amputation. Radiological examination of the right leg revealed tibial hypoplasia and the right foot displayed 8 digits with corresponding metatarsals and tarsals, whereas the left leg revealed 2 extra digits on the medial aspect of the foot with corresponding metatarsal and tarsal bones. Anatomical dissection of the right foot revealed that it was divided into halves consisting of 8 toes with corresponding metatarsals and tarsals, as well as tibial hypoplasia and absence of the great toe. Diplopodia associated with tibial hypoplasia and syndactyly can be treated surgically, and the present case report details the clinical, radiological, and anatomical elements of this rare deformity.
Fulltext A review of the recent trend in the synthesis of carbon nanomaterials derived from oil palm by-product materials

Zakaria NZJ, Rozali S, Mubarak NM, Ibrahim S

Biomass Convers Biorefin, 2022 Feb 11.
PMID: 35194538 DOI: 10.1007/s13399-022-02430-3

Grown only in humid tropical conditions, the palm tree provides high-quality oil essential for cooking and personal care or biofuel in the energy sector. After the refining process, this demand could cause numerous oil palm biomass waste management problems. However, the emergence of carbon nanomaterials or CNMs could be a great way to put this waste to a good cause. The composition of the palm waste can be used as a green precursor or starting materials for synthesizing CNMs. Hence, this review paper summarizes the recent progress for the CNMs production for the past 10 years. This review paper extensively discusses the method for processing CNMs, chemical vapor deposition, pyrolysis, and microwave by the current synthesis method. The parameters and conditions of the synthesis are also analyzed. The application of the CNMs from palm oil and future recommendations are also highlighted. Generally, this paper could be a handy guide in assisting the researchers in exploring economic yet simple procedures in synthesizing carbon-based nanostructured materials derived from palm oil that can fulfill the required applications.
Access and Affordability of Medicines in Malaysia: Need for a National Pricing Policy

Wong SL, Ibrahim S, Abdul Kadir N, Mohd Salleh S

Appl Health Econ Health Policy, 2019 10;17(5):641-654.
PMID: 31093937 DOI: 10.1007/s40258-019-00480-9

BACKGROUND: High medicines prices are a barrier to medicines access, and their impact is greater in developing countries.
OBJECTIVE: This study assessed the availability, prices and affordability of medicines in public and private sectors in Malaysia to understand the pharmaceutical environment and guide policy recommendations.
METHODS: This nationwide cross-sectional study adapted the World Health Organization/Health Action International (WHO/HAI) methodology. A total of 87 premises from both public and private sectors participated in this study. Data on 50 medicines were collected to analyze availability, prices and affordability. Medicine prices were compared against the international reference prices (IRPs), and affordability was assessed by daily income level.
RESULTS: In the public sector, the average availability of generics (74.8%) was higher than that of the originator brand name products (19.4%). However, in the private sector, the availability of originator brands was higher (52.2%) than generics (49.1%). Procurement prices in the public sector were up to 1.5 times the IRPs, but up to 8.4 times in the private sector. The study also observed large price variation across medicines in the private sector. Median retail mark-ups in private hospitals (generics 166.9%; originators 51.0%) were higher than in retail pharmacies (generics 94.7%; originators 22.4%). Generics were generally affordable, but originator brands were unaffordable.
CONCLUSION: Current policies on generic medicines need to be strengthened to improve the availability and use of generics in the country. High medicine prices and large price variation in the current free market suggest that coherent pricing policies and regulations are needed to safeguard the accessibility and affordability of medicines for the people.
Add-on rosiglitazone therapy improves plasminogen activity and high-density lipoprotein cholesterol in type 2 diabetes mellitus

Mustaffa N, Ibrahim S, Abdullah WZ, Yusof Z

Blood Coagul Fibrinolysis, 2011 Sep;22(6):512-20.
PMID: 21537159 DOI: 10.1097/MBC.0b013e32834740ba

Rosiglitazone is an oral hypoglycaemic agent of the thiazolidinedione group. This study aimed to assess changes in the diabetic prothrombotic state via plasminogen activity and changes in surrogate markers of atherosclerotic burden via ankle-brachial pressure index (ABPI) measurements after rosiglitazone was added to a pre-existing type 2 diabetes mellitus treatment regime. A nonblinded interventional study was designed. Fifty-nine patients were enrolled. Rosiglitazone-naïve patients were prescribed oral rosiglitazone 4 mg daily for 10 weeks. ABPI, plasminogen activity, glycosylated haemoglobin (HbA1c) and fasting lipid profile were measured pretreatment and post-treatment. Forty-eight patients completed the study. At the end of this study, mean plasminogen activity improvement was nearly 16% (P<0.05), mean ABPI improvement was 0.01 (P=0.439), mean HbA1c reduction was 0.51% (P<0.05), mean total cholesterol (TC) increase was 0.36 mmol/l (P<0.05), mean high-density lipoprotein cholesterol (HDL-C) increase was 0.15 mmol/l (P<0.05) and mean low-density lipoprotein cholesterol increased by 0.19 mmol/l (P=0.098). Rosiglitazone significantly improved plasminogen activity. There was also significant HbA1c reduction, and rise in both TC and HDL-C. Thus, rosiglitazone potentially improves the atherosclerotic burden and prothrombotic state. In future, more studies are needed to confirm the relationship between rosiglitazone, fibrinolytic system and atheromatous reduction in type 2 diabetes mellitus.
Fulltext An approach for Web service selection based on confidence level of decision maker

Khezrian M, Jahan A, Kadir WM, Ibrahim S

PLoS One, 2014;9(6):e97831.
PMID: 24897426 DOI: 10.1371/journal.pone.0097831

Web services today are among the most widely used groups for Service Oriented Architecture (SOA). Service selection is one of the most significant current discussions in SOA, which evaluates discovered services and chooses the best candidate from them. Although a majority of service selection techniques apply Quality of Service (QoS), the behaviour of QoS-based service selection leads to service selection problems in Multi-Criteria Decision Making (MCDM). In the existing works, the confidence level of decision makers is neglected and does not consider their expertise in assessing Web services. In this paper, we employ the VIKOR (VIšekriterijumskoKOmpromisnoRangiranje) method, which is absent in the literature for service selection, but is well-known in other research. We propose a QoS-based approach that deals with service selection by applying VIKOR with improvement of features. This research determines the weights of criteria based on user preference and accounts for the confidence level of decision makers. The proposed approach is illustrated by an example in order to demonstrate and validate the model. The results of this research may facilitate service consumers to attain a more efficient decision when selecting the appropriate service.
Fulltext An approach for developing integrated undergraduate medical curriculum

Akram A, Rizwan F, Sattar K, Hadi JIS, Meo SA

Pak J Med Sci, 2018 9 8;34(4):804-810.
PMID: 30190732 DOI: 10.12669/pjms.344.14565

Background and Objectives: Medical schools are to develop integrated medical curricula because the term 'integrated curriculum' has grown up and flourished globally and it has become mandatory to align the medical education with the global concept in Pakistan. This paper aims to present a guideline to design an undergraduate integrated medical curriculum.
Methods: Various themes are used to develop integrated curriculum which are basic medical science, simulation skills, clinical science, personality development, research, entrepreneurship and pre specialization. Each theme is subdivided, termed a module and its contents primarily focus on particular aspect.
Results: Knowledge, skill and attitude, embodied in themes or modules, are planted in specific way that they have horizontal as well as vertical integration. There is no boundary of various traditional disciplines in template of five years curriculum. For example, diagnosis is a theme which carries contents from medicine, surgery, orthopedics etc.
Conclusion: The blueprint introduced in this paper would help medical educators to draft integrated medical curricula for those institutions which intend to switch their medical programs from traditional to integrated one.
An efficient and economical treatment for batik textile wastewater containing high levels of silicate and organic pollutants using a sequential process of acidification, magnesium oxide, and palm shell-based activated carbon application

Birgani PM, Ranjbar N, Abdullah RC, Wong KT, Lee G, Ibrahim S, et al.

J Environ Manage, 2016 Dec 15;184(Pt 2):229-239.
PMID: 27717677 DOI: 10.1016/j.jenvman.2016.09.066

Considering the chemical properties of batik effluents, an efficient and economical treatment process was established to treat batik wastewater containing not only high levels of Si and chemical oxygen demand (COD), but also toxic heavy metals. After mixing the effluents obtained from the boiling and soaking steps in the batik process, acidification using concentrated hydrochloric acid (conc. HCl) was conducted to polymerize the silicate under acidic conditions. Consequently, sludge was produced and floated. XRD and FT-IR analyses showed that wax molecules were coordinated by hydrogen bonding with silica (SiO2). The acidification process removed ∼78-95% of COD and ∼45-50% of Si, depending on the pH. In the next stage, magnesium oxide (MgO) was applied to remove heavy metals completely and almost 90% of the Si in the liquid phase. During this step, about 70% of COD was removed in the hydrogel that arose as a consequence of the crosslinking characteristics of the formed nano-composite, such as magnesium silicate or montmorillonite. The hydrogel was composed mainly of waxes with polymeric properties. Then, the remaining Si (∼300 mg/L) in the wastewater combined with the effluents from the rinsing steps was further treated using 50 mg/L MgO. As a final step, palm-shell activated carbon (PSAC) was used to remove the remaining COD to
An elbow dislocation in a child with missed medial epicondyle fracture and late ulnar nerve palsy

Haflah NH, Ibrahim S, Sapuan J, Abdullah S

J Pediatr Orthop B, 2010 Sep;19(5):459-61.
PMID: 20555271 DOI: 10.1097/BPB.0b013e32833b6032

Elbow dislocations associated with a medial epicondyle fracture and ulnar nerve palsy are uncommon injuries. We present the case of an 11-year-old girl with an elbow dislocation treated by closed manual reduction. The medial epicondyle fracture was missed initially until she developed an ulnar nerve palsy 2 months later. Intraoperatively we discovered the bony epicondyle piercing the joint capsule and compressing the ulnar nerve. Removal of the bony fragment relieved her symptoms and she returned to normal activities at 1 year follow-up. We would like to highlight this rare occurrence and present the detailed history and management of this case.
Fulltext An extendable optical fibre probe survey meter for naturally occurring radioactive material (NORM) and other weak emitters

Zubair HT, Bradley DA, Khairina MD, Oresegun A, Basaif A, Othman J, et al.

Sci Rep, 2023 Jul 24;13(1):11918.
PMID: 37488183 DOI: 10.1038/s41598-023-39180-9

We have developed a radioluminescence-based survey meter for use in industries in which there is involvement in naturally occurring radioactive material (NORM), also in support of those needing to detect other weak emitters of radiation. The functionality of the system confronts particular shortcomings of the handheld survey meters that are currently being made use of. The device couples a LYSO:Ce scintillator with a photodetector via a polymer optical fibre waveguide, allowing for "intrinsically safe" inspection within pipework, separators, valves and other such component pieces. The small-diameter optical fibre probe is electrically passive, immune to electromagnetic interference, and chemically inert. The readout circuit is entirely incorporated within a handheld casing housing a silicon photomultiplier (SiPM) detection circuit and a microprocessor circuit connected to an LCD display. A 15 m long flexible PMMA optical fibre waveguide is butt coupled to an ABS plastic probe that retains the LYSO:Ce scintillator. Initial tests have included the use of lab-based mixed gamma-ray sources, measurements being made in concert with a reference conventional GM survey-meter. Characterization, via NORM sources at a decontamination facility, has shown useful sensitivity, covering the dose-rate range 0.10- to 28 µSv h-1 (R-squared 0.966), extending to 80 µSv/h as demonstrated in use of a Cs-137 source. The system is shown to provide an effective tool for detection of radioactivity within hard to access locations, in particular for sources emitting at low radiation levels, down to values that approach background.
An integrated assessment of seawater intrusion in a small tropical island using geophysical, geochemical, and geostatistical techniques

Kura NU, Ramli MF, Ibrahim S, Sulaiman WN, Aris AZ

Environ Sci Pollut Res Int, 2014;21(11):7047-64.
PMID: 24532282 DOI: 10.1007/s11356-014-2598-0

In this study, geophysics, geochemistry, and geostatistical techniques were integrated to assess seawater intrusion in Kapas Island due to its geological complexity and multiple contamination sources. Five resistivity profiles were measured using an electric resistivity technique. The results reveal very low resistivity <1 Ωm, suggesting either marine clay deposit or seawater intrusion or both along the majority of the resistivity images. As a result, geochemistry was further employed to verify the resistivity evidence. The Chadha and Stiff diagrams classify the island groundwater into Ca-HCO3, Ca-Na-HCO3, Na-HCO3, and Na-Cl water types, with Ca-HCO3 as the dominant. The Mg(2+)/Mg(2+)+Ca(2+), HCO3 (-)/anion, Cl(-)/HCO3 (-), Na(+)/Cl(-), and SO4 (2-)/Cl(-) ratios show that some sampling sites are affected by seawater intrusion; these sampling sites fall within the same areas that show low-resistivity values. The resulting ratios and resistivity values were then used in the geographical information system (GIS) environment to create the geostatistical map of individual indicators. These maps were then overlaid to create the final map showing seawater-affected areas. The final map successfully delineates the area that is actually undergoing seawater intrusion. The proposed technique is not area specific, and hence, it can work in any place with similar completed characteristics or under the influence of multiple contaminants so as to distinguish the area that is truly affected by any targeted pollutants from the rest. This information would provide managers and policy makers with the knowledge of the current situation and will serve as a guide and standard in water research for sustainable management plan.
An overview of groundwater chemistry studies in Malaysia

Kura NU, Ramli MF, Sulaiman WNA, Ibrahim S, Aris AZ

Environ Sci Pollut Res Int, 2018 Mar;25(8):7231-7249.
PMID: 26686857 DOI: 10.1007/s11356-015-5957-6

In this paper, numerous studies on groundwater in Malaysia were reviewed with the aim of evaluating past trends and the current status for discerning the sustainability of the water resources in the country. It was found that most of the previous groundwater studies (44 %) focused on the islands and mostly concentrated on qualitative assessment with more emphasis being placed on seawater intrusion studies. This was then followed by inland-based studies, with Selangor state leading the studies which reflected the current water challenges facing the state. From a methodological perspective, geophysics, graphical methods, and statistical analysis are the dominant techniques (38, 25, and 25 %) respectively. The geophysical methods especially the 2D resistivity method cut across many subjects such as seawater intrusion studies, quantitative assessment, and hydraulic parameters estimation. The statistical techniques used include multivariate statistical analysis techniques and ANOVA among others, most of which are quality related studies using major ions, in situ parameters, and heavy metals. Conversely, numerical techniques like MODFLOW were somewhat less admired which is likely due to their complexity in nature and high data demand. This work will facilitate researchers in identifying the specific areas which need improvement and focus, while, at the same time, provide policymakers and managers with an executive summary and knowledge of the current situation in groundwater studies and where more work needs to be done for sustainable development.
Fulltext Analysis of sequence variations in low-density lipoprotein receptor gene among Malaysian patients with familial hypercholesterolemia

Al-Khateeb A, Zahri MK, Mohamed MS, Sasongko TH, Ibrahim S, Yusof Z, et al.

BMC Med Genet, 2011;12:40.
PMID: 21418584 DOI: 10.1186/1471-2350-12-40

Familial hypercholesterolemia is a genetic disorder mainly caused by defects in the low-density lipoprotein receptor gene. Few and limited analyses of familial hypercholesterolemia have been performed in Malaysia, and the underlying mutations therefore remain largely unknown.We studied a group of 154 unrelated FH patients from a northern area of Malaysia (Kelantan). The promoter region and exons 2-15 of the LDLR gene were screened by denaturing high-performance liquid chromatography to detect short deletions and nucleotide substitutions, and by multiplex ligation-dependent probe amplification to detect large rearrangements.
Fulltext Angular Deformities of the Knee in Children Treated with Guided Growth

Jamil K, Yahaya MY, Abd-Rasid AF, Ibrahim S, Abdul-Rashid AH

Malays Orthop J, 2021 Jul;15(2):26-35.
PMID: 34429819 DOI: 10.5704/MOJ.2107.005

Introduction: The guided growth technique is an alternative to corrective osteotomy for treating angular deformities of the extremities. It has the advantage of being minimally invasive and is effective in a growing child. This study reports on the outcome of guided growth technique using a plate in correcting knee angular deformities.
Material and Methods: We conducted a retrospective study of children with angular deformity of the knee treated by the guided growth technique from January 2010 to December 2015 in a tertiary centre. The guided growth technique was done using either the flexible titanium plate (8-plate) or the 2-hole reconstruction plate. Correction of deformity was assessed on radiographs by evaluating the mechanical axis deviation and tibiofemoral angle. The implants were removed once deformity correction was achieved.
Results: A total of 17 patients (27 knees) were evaluated. Twenty-two knees (81.5%) achieved complete correction of the deformity. The median age was 4.0 (interquartile range 3.0-6.0) years and the median Body Mass Index (BMI) was 26.0 (25.0-28.0). There were 7 unilateral and 10 bilateral deformities with different pathologies (14 tibia vara, 3 genu valgus). The median rate of correction was 0.71° per month. One patient (1 knee) had screw pull-out and two patients (4 knees) had broken screws in the proximal tibia. Three patients (5 knees) failed to achieve complete correction and were subsequently treated with corrective osteotomies. Out of five patients (8 knees) who were followed-up for at least 12 months after removal of hardware, two had rebound deformities. No permanent growth retardation occurred in our patients.
Conclusion: Our outcome for guided growth to correct knee angular deformity was similar to other studies. Guided growth is safe to perform in children below 12 years old and has good outcome in idiopathic genu valgus and Langeskiold II for tibia vara. Patients should be observed for recurrence until skeletal maturity following implant removal.
Fulltext Anxiety Reaction in Children During Cast Removal using Oscillating Saw versus Cast Shear - A Randomised, Prospective Trial

Mohamed-Zain NA, Jamil K, Penafort R, Singh A, Ibrahim S, Abdul-Rashid AH

Malays Orthop J, 2021 Jul;15(2):122-128.
PMID: 34429832 DOI: 10.5704/MOJ.2107.018

Introduction: To compare the anxiety levels demonstrated by children during cast removal procedure between oscillating saw vs cast shear methods.
Material and methods: A randomised prospective study of 102 children (mean age 8.3 ± 3.5 years) with fractures involving upper or lower limbs. Children undergoing removal of cast were divided into 2 groups; either by an oscillating saw or a cast cutting shear. The level of anxiety was assessed by recording the heart rate with a portable fingertip pulse oximeter before, during and after removal of the cast. Objective assessment was performed by documenting the fear level on Children's Fear Scale (CFS).
Results: There was a significant increase in the heart rate of children during cast removal while using the oscillating saw compared to cast shear (p<0.05). The noise level produced by the saw exceeded 80 dB (mean 103.3 dB). The fear level was significantly lower in the cast shear group (p<0.05).
Conclusion: The noise produced by the oscillating saw was associated with an increased anxiety level in children undergoing cast removal. Cast shear is a simple and inexpensive instrument that can be used for cast removal in overly anxious children.
Fulltext Application of geophysical techniques for 3D geohazard mapping to delineate cavities and potential sinkholes in the northern part of Kuala Lumpur, Malaysia

Bakhshipour Z, Huat BB, Ibrahim S, Asadi A, Kura NU

ScientificWorldJournal, 2013;2013:629476.
PMID: 24501583 DOI: 10.1155/2013/629476

This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems.
Arsenite removal using a pilot system of ultrasound and ultraviolet followed by microfiltration

Cui M, Jang M, Ibrahim S, Park B, Cho E, Khim J

Ultrason Sonochem, 2014 Jul;21(4):1527-34.
PMID: 24500068 DOI: 10.1016/j.ultsonch.2014.01.001

Batch and continuous-flow pilot tests using ultrasound (US), ultraviolet (UV) and a combination of US and UV were conducted to determine the oxidation rates of arsenite [As(III)]. Compared to the single processes of US or UV, the combined US/UV system was more effective for As(III) oxidation with a synergy index of more than 1.5. A high rate constant of As(III) removal was obtained as ferrous [Fe(II)] ions existed. Like the pseudo-Fenton reaction, Fe(II) species can participate in the production of additional ·OH by reacting with H2O2 produced by US, before being oxidized to Fe(III). From the results of batch tests, the optimum molar ratio of Fe(II)/As(III) and pH were found to be 83 and 6-9.5, respectively. Similarly, the continuous-flow pilot tests showed that US/UV system could remove As(III) below the regulation [10 μg L(-1) as total As (Astot)] at 91 of molar ratio [Fe(II)/As(III)] and 3-h HRT. The continuous-stirred-tank-reactor (CSTR) modeling showed that the scavenging effect of anionic species (Cl(-) and CO3(2-)) for ·OH might prevail in the single processes, whereas it is insignificant in the combined process. Without using chemicals, microfiltration (MF) was adopted to treat sludge produced in oxidation step. In terms of an engineering aspect, the operational critical flux (CF) and cycle time were also optimized through the continuous-flow tests of MF system. As an energy-utilizing oxidation technique that does not require a catalyst, the combined energy system employing US/UV followed by MF could be a promising alternative for treating As(III) and Fe(II) simultaneously.

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