Properties of a CaCu3−xMn4+xO12 system synthesized via a solid-state reaction

Zainal Arifin Ahmad 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.6

Effect of rice husk ash and silica fume in ternary system on the properties of blended cement paste and concrete

Zainal Arifin Ahmad,Bun Kim Ngun,Hasmaliza Mohamad,Etsuo Sakai 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

The effects of rice husk ash (RHA) and fume silica (SF) in both binary and ternary systems on the properties of cement pastes and the compressive strength of concretes were studied. The amount of cement replacement in both systems was 15%. The free calcium hydroxide (Ca(OH)2) content was analyzed using XRD and TG/DTA for the hardened cement pastes. The results showed that the amount of Ca(OH)2 decreased significantly the curing ages for all blended cement pastes. At 28 days, the amount of Ca(OH)2 in OPC is 17.31%, 8.18% in RHA and 6.43% in SF replacements, respectively. The ternary system similarly indicates a significant reduction of Ca(OH)2 content. The compressive strength of concretes was improved significantly by blending the aforementioned materials in both systems. In the ternary system, the concretes containing 7.5%SF and 7.5% RHA gave remarkable improvement in the compressive strength. For example after 90 days curing, the strength is 57.8 MPa whilst only 47.5 MPa for OPC. Therefore, the application of proper ratios of RHA and SF in a ternary system is able to increase the properties of the concrete.

Prevalence of Depression in Breast Cancer Survivors: a Systematic Review of Observational Studies

Zainal, Nor Zuraida,Nik-Jaafar, Nik Ruzyanei,Baharudin, Azlin,Sabki, Zuraida Ahmad,Ng, Chong Guan Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.4

Background: Depression is common in breast cancer patients. The aim of this paper was to make a systematic review of its prevalence and associated factors oin breast cancer survivors. Materials and Methods: An extensive systematic electronic review (PUBMED, CINAHL, PsyINFO and Ovid) and handsearch were carried out to retrieve published articles up to November 2012, using Depression OR Dysthymia AND (Cancer OR Tumor OR Neoplasms as the keywords. Information about the design of the studies, measuring scale, characteristics of the participants, prevalence of depression and its associated factors from the included studies were extracted and summarized. Results: We identified 32 eligible studies that recruited 10,826 breast cancer survivors. Most were cross-sectional or prospective designed. The most frequent instrument used to screen depression was the Center for Epidemiological Studies for Depression (CES-D, n=11 studies) followed by the Beck Depression Inventory (BDI, n=6 studies) and the Hospital Anxiety and Depression Scale (HADS, n=6 studies). CES-D returned about similar prevalence of depression (median=22%, range=13-56%) with BDI (median=22%, range=17-48%) but higher than HADS (median=10%, range=1-22%). Depression was associated with several socio-demographic variables, cancer-related factors, treatment-related factors, subject psychological factors, lifestyle factors, social support and quality of life. Conclusions: Breast cancer survivors are at risk for depression so that detection of associated factors is important in clinical practice.

Reliability and Validity of the Malay Version of the Breast-Impact of Treatment Scale (MVBITS) in Breast Cancer Women undergoing Chemotherapy

Zainal, Nor Zuraida,Shuib, Norley,Bustam, Anita Zarina,Sabki, Zuraida Ahmad,Guan, Ng Chong Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1

Background: Body image dissatisfaction among breast cancer survivors has been associated with psychological stress resultant from breast cancer and resultant surgery. This study aimed to examine the psychometric properties of the Malay Version of the Breast-Impact of Treatment Scale (MVBITS) and to investigate the associations of retained factors with the Hospital Anxiety and Depression Scale (HADS) and the Rosenberg Self-Esteem Scale (RSES). Materials and Methods: The MVBITS was 'forward-backward' translated from English to Malay and then administered to 70 female breast cancer patients who came to the Oncology Clinic of University Malaya Medical Centre, Kuala Lumpur, Malaysia to undergo chemotherapy. Principal component analysis (PCA) with varimax rotation was performed to explore the factor structure of the MVBITS. Associations of retained factors were estimated with reference to Spearman correlation coefficients. Results: The internal consistency reliability of MVBITS was good (Cronbach's alpha 0.945) and showed temporal stability over a 3-week period. Principal component analysis suggested two factors termed as 'Intrusion' and 'Avoidance' domains. These factors explained 70.3% of the variance. Factor 1 comprised the effects of breast cancer treatment on the emotion and thought, while Factor 2 informed attempts to limit exposure of the body to self or others. The Factor 1 of MVBITS was positively correlated with total, depression and anxiety sub-scores of HADS. Factor 2 was positively correlated with total and anxiety sub-scores of HADS. MVBITS was also positively correlated with the RSES scores. Conclusions: The results showed that the Malay Version of Breast-Impact of Treatment Scale possesses satisfactory psychometric properties suggesting that this instrument is appropriate for assessment of body change stress among female breast cancer patients in Malaysia.

Microstructure Evolution and Shear Strength Study of Sn–9Zn and Sn–8Zn–3Bi on Cu Substrate

Ramani Mayappan,Zainal Arifin Ahmad 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.1

In electronics assembly, solder joints not only serve as mechanical supporters-, but also as heat removers. Therefore, solder joint reliability is a major concern not only during production, but also during the life time of electronic products. It can be pointed out that reliability of solder joint determines the lifetime of electronics products. This issue becomes more important with the use of Pb-free soldering alloys. This study focuses on the reliability of Sn–9Zn and Sn–8Zn–3Bi lead-free solder joints with Cu substrates. This study deals with interface intermetallic morphology, solder joint strength and fracture surface analysis after isothermal aging at 50, 100, and 150°C for 100, 250, and 500 h. For all aging conditions, a flat Cu 5 Zn 8 intermetallic was formed, and as the aging conditions increased, Cu atoms diffused through the intermetallic to form isolated Cu5 Zn8 intermetallics in the bulk solder. Furthermore, Sn atoms from bulk the solder diffused through the intermetallic to form Cu6 Sn5 on the Cu side. The formation of a thick Cu5 Zn8 intermetallic and the diffusion of Sn and Zn atoms created a depletion zone near the solder/intermetallic boundary, which weakened the joint strength. As the intermetallic layer thickness increased, the joint strength decreased as the aging increased. The fracture path generally occurred at the bulk solder/intermetallic boundary under all aging conditions.

A New Optimum Design for a Single Input Fuzzy Controller Applied to DC to AC Converters

Shahrin Md. Ayob,Zainal Salam,Naziha Ahmad Azli 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.3

In this paper, the design of an optimum single input Fuzzy controller for application in dc to ac converters is presented. Contrary to conventional Fuzzy controllers, the proposed controller has a smaller number of rules and tuning parameters but is capable of performing identically to a conventional controller. These benefits lead to a simpler controller design. The controller is designed as a PI controller for small-signal disturbances. However, for optimum large-signal performance, heuristic tuning is used. The tuning is less complicated and hence optimum large-signal performance is achievable. The system is simulated and a hardware prototype was developed for comparison purposes.

A Hybrid of Back Propagation Neural Network and Genetic Algorithm for Optimization of Collagen Extraction from Malaysian Cultured Catfish (Hybrid Clarias sp.)

Peck Loo Kiew,Zainal Ahmad,Mashitah Mat Don 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.2

Fractional factorial design (FFD) was applied to evaluate the effects of various process parameters in influencing the extraction efficiency of pepsin soluble collagen (PSC) from muscles of cultured catfish (Clarias gariepinus×C. macrocephalus). Result of the first order factorial design showed that acetic acid concentration, acid extraction time, acetic acid to muscles ratio, and stirring speed posed significant effect (P<0.05) on the yield of PSC obtained at the end of the extraction process. Two different artificial intelligence techniques namely artificial neural network (ANN) and genetic algorithm (GA) were then integrated for optimizing the extraction conditions to obtain the highest yield of PSC. The ANN was trained using the back propagation algorithm. A model was successfully generated with R2 value of 0.9527 and MSE value of 0.1672 for unseen data set, implying a good generalization of the network. Input parameters of the established ANN model were subsequently optimized using GA. The hybrid of ANN-GA model predicted a maximum extraction yield of PSC at 238.25 mg/g under the following conditions: an acetic acid concentration of 0.70 M, the acetic acid to muscles ratio of 25.78 mL/g,and the stirring speed of 432.50 rpm. Verification of the optimization showed the percentage error differences between the experimental and predicted values were less than 5%, indicating excellent modeling, predicting ability and optimization by the ANN-GA model.

PWM DC-AC Converter Regulation using a Multi-Loop Single Input Fuzzy PI Controller

Shahrin Md. Ayob,Naziha Ahmad Azli,Zainal Salam 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1

This paper presents a PWM dc-ac converter regulation using a Single Input Fuzzy PI Controller (SIFPIC). The SIFPIC is derived from the signed distanced method, which is a simplification of a conventional fuzzy controller. The simplification results in a one-dimensional rule table, that allows its control surface to be approximated by a piecewise linear relationship. The controller multi-loop structure is comprised of an outer voltage and an inner current feedback loop. To verify the performance of the SIFPIC, a low power PWM dc-ac converter prototype is constructed and the proposed control algorithm is implemented. The experimental results show that the SIFPIC performance is comparable to a conventional Fuzzy PI controller, but with a much reduced computation time.

A New Optimum Design for a Single Input Fuzzy Controller Applied to DC to AC Converters

Ayob, Shahrin Md.,Salam, Zainal,Azli, Naziha Ahmad The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.3

In this paper, the design of an optimum single input Fuzzy controller for application in dc to ac converters is presented. Contrary to conventional Fuzzy controllers, the proposed controller has a smaller number of rules and tuning parameters but is capable of performing identically to a conventional controller. These benefits lead to a simpler controller design. The controller is designed as a PI controller for small-signal disturbances. However, for optimum large-signal performance, heuristic tuning is used. The tuning is less complicated and hence optimum large-signal performance is achievable. The system is simulated and a hardware prototype was developed for comparison purposes.

PWM DC-AC Converter Regulation using a Multi-Loop Single Input Fuzzy PI Controller

Ayob, Shahrin Md.,Azli, Naziha Ahmad,Salam, Zainal The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.1

This paper presents a PWM dc-ac converter regulation using a Single Input Fuzzy PI Controller (SIFPIC). The SIFPIC is derived from the signed distanced method, which is a simplification of a conventional fuzzy controller. The simplification results in a one-dimensional rule table, that allows its control surface to be approximated by a piecewise linear relationship. The controller multi-loop structure is comprised of an outer voltage and an inner current feedback loop. To verify the performance of the SIFPIC, a low power PWM dc-ac converter prototype is constructed and the proposed control algorithm is implemented. The experimental results show that the SIFPIC performance is comparable to a conventional Fuzzy PI controller, but with a much reduced computation time.