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Search Results: 1 - 10 of 8014 matches for " Norhayati Ahmad "
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Characterization and Modification of Mesoporous Silica Nanoparticles Prepared by Sol-Gel
Meysam Keshavarz,Norhayati Ahmad
Journal of Nanoparticles , 2013, DOI: 10.1155/2013/102823
Abstract: Mesoporous silica nanoparticles (MSNs) were synthesized by sol-gel reaction at normal pressure by using TEOS as a silica source and CTAB as a directing agent in ammonia solution at 323?K subsequently calcined at 823?K. Then inorganic pores were modified with metal-supported MSN with attention to the acidity, surface area, pore size, and ability of ion exchange. Crystalline size was shown to decrease up to 20 molar ratios of Si/Al followed by increasing while further adding nanoparticles-aluminium. Moreover, the XRD patterns revealed the mesostructured material for all with 2D hexagonal structure. The obtained results from the XRD patterns were confirmed by using BET and EDX. The BET surface areas revealed the spherical shape for all samples with a decrease in the pore volume and surface area for various AlMSNs which emphasized that the loading of Al and was compatible with XRD results. MSN was prepared by sol-gel methods followed by loading of Al in order to prepare AlMSN which possess strong Lewis acidic sites. This modification occurred by using various molar ratios of 0, 5, 10, 20, 50, and 100 Si/Al, respectively. The XRD patterns of various ratios of Si/Al were interpreted in terms of strain, nanocrystalline size, and distribution of the particle size by deriving Wiliamson Hall equation. 1. Introduction More than 10 years passed since the discovery of the so-called M41S mesoporous silica materials, and the synthesis of the mesoporous materials with different characterizes has been gaining increasing attention. This study attempts to reveal the dependence effect of various ratios of Si/Al additive on nanocrystalline size, residual stress and physicochemical property of mesostructure siliceous nanoparticles (MSN) which can give a better insight of its application on petroleum refinery and petrochemical industries. Moreover, the nobility of this research might be the utilization of XRD pattern to find out nanocrystalline size, residual stress, and microstructure. The surfactant-templating method has been extended to the synthesis of nonsilica oxide mesoporous materials [1–3]. Potential application of mesoporous transition metal oxides has been found in the fields of electromagnetic, photoelectronics, catalysis, and separation [4]. By using cationic surfactants with quaternary ammonium derivatives and then nonionic alkoxysilanes, a series of ordered mesoporous silicas had been synthesized [5–7] and the various alkaline or acidic [8–10] conditions were used. These experiments have shown better condensation of the silanol groups in mesoporous silica
A Matrix Variance Inequality for k-Functions
Norhayati Rosli,Wan Muhamad Amir W Ahmad
Matematika , 2007,
Abstract: In this paper a course of solving variational problem is considered. [2] obtained what appears to be specialized inequality for a variance, namely, that for a standard normal variable X , V ar[g(x)] ≥ E[g’(x)]2 . However both of the simplicity and usefulness of the inequality has generated a plethora of extensions, as well as alternative proofs. [5] had focused on a result of two random variables for the normal and gamma distribution. They obtained the result of normal distribution with k functions, without proving and the proof is presented here. This paper also extend the result obtained by [5] to the k functions for the gamma distribution.
Khan M. Farid?,Ismail,Norhayati,Yusof,Ahmad Pauzi M.?,Khan,Gul Majid?
无机化学学报 , 1998,
Abstract: 自人类有历史记载以来,铜及其配合物即用作药物。铜是人体必需的金属元素。人体的正常代谢过程需要它们,但无法体内合成,因此,需要每天从饮食摄取和吸收。生物药学家和研究者以极大的努力彻底地了解铜及其配合物在生物体系中的作用,希望获得更多地信息以利于人类疾病的预防和治疗。本综述评述了铜在组织中的分配和代谢、铜依赖酶、在病态时铜的非正常代谢、铜配合物的药疗活性和抑制氧自由基的产生。
From Antarctica or Asia? New colonization scenario for Australian-New Guinean narrow mouth toads suggested from the findings on a mysterious genus Gastrophrynoides
Atsushi Kurabayashi, Masafumi Matsui, Daicus M Belabut, Hoi-Sen Yong, Norhayati Ahmad, Ahmad Sudin, Mitsuru Kuramoto, Amir Hamidy, Masayuki Sumida
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-175
Abstract: Six nuclear and two mitochondrial genes (approx. 8 kbp) were sequenced from 22 microhylid frog species representing eight subfamilies. The maximum likelihood and Bayesian analyses could not fully elucidate the subfamilial relationships, suggesting a rapid radiation of these taxa between 85 and 66 million years ago. In contrast, generic relationships of Asian microhylines were generally well resolved.Our results clearly showed that one of two problematic Asian genera, Phrynella, was nested in the clade of the Asian subfamily Microhylinae. By contrast, Gastrophrynoides occupied the most basal position of the Australian-New Guinean subfamily Asterophryinae. The estimated divergence of Gastrophrynoides from other asterophryine was unexpectedly around 48 million years ago. Although a colonization scenario via Antarctica to the Australian-New Guinean landmass has been suggested for Asterophryinae, our finding suggested a novel colonization route via Indo-Eurasia.Microhylidae is a large anuran family containing 487 species equivalent to 8% of all frogs [1]. This family belongs to the phylogenetically-nested anuran group, Neobatrachia, and forms Ranoides with Afrobatrachia (including the families, Arthroleptidae, Brevicipitidae, Hemisotidae, and Hyperoliidae) and Natatanura (= Ranidae sensu lato).Members of the Microhylidae occur in most continents and several large islands, i.e., Africa, Eurasia (not in the subcontinent of Europe), South and North America, Australia, New Guinea, and Madagascar. Since Frost et al. [1], the subfamilial classification of this family had been largely modified based on new findings from several molecular phylogenetic studies [2,3]. Consequently, eleven microhylid subfamilies are now recognized [4] and each subfamily generally occurs in one landmass area derived from the Gondwana supercontinent as follows: Asterophryinae (Australia-New Guinea); Cophylinae, Dyscophinae, and Scaphiophryninae (Madagascar); Gastrophryninae and Otophryninae (South an
Type 2 diabetes with good glycemic control have improved insulin response and lower non-esterified fatty acid level after a meal challenge  [PDF]
Norhayati Yahaya, Win Mar Kyi, Norhayati Mohd Noor, Wan Mohamed Wan Bebakar
Journal of Diabetes Mellitus (JDM) , 2012, DOI: 10.4236/jdm.2012.21001
Abstract: Background: Pathogenesis of type 2 diabetes (T2DM) involves defects in β-cell function with impaired first and second phase insulin response, and reduced insulin sensitivity. Diabetic dyslipidemia is an important and common risk factor for coronary heart disease (CHD). Aims: This study examined the effect of glycemic control on post prandial insulin and lipid parameters in response to a standardised meal challenge among Type 2 diabetes patients with good and poor glycemic control. Methods: We cross-sectionally studied 31 T2DM patients with good glycemic control and 32 T2DM patients with poor glycemic control. Subjects were given, after minimum 10 hours of fasting, a standard meal containing 58% fat. Fasting and serial postprandial blood samples were taken over 8 hours to determine levels of triglyceride, direct LDL-C, apoB lipoprotein, non-esterified-fatty-acid, insulin and blood glucose. Results: Post prandial NEFA was significantly higher in poor controlled diabetes patients compared to good control diabetes patients (p = 0.019), and post-hoc analysis showed significant difference from 3 hours post prandial to 4 hours post prandial, where p= 0.021. Although the difference in insulin between the 2 groups did not reach statistical significance (p =0.058), post-hoc analysis showed significant difference between the 2 groups from fasting to 1 hour post prandial (p = 0.034) despite postprandial glucose being significantly higher in poor controlled diabetes patients (p < 0.001), throughout the postprandial period. Conclusion: T2DM patients with good glycemic control have improved insulin response with lower non-esterified fatty acid.
Webs of Culture: Applying InterculturalCommunication Theory to Understand Distributed Decision-Making Processes
Norhayati Zakaria,Derrick Cogburn
International Business Research , 2009, DOI: 10.5539/ibr.v1n3p115
Abstract: The overarching research question in this paper is: What is the influence of high-versus-low context cultural orientations on effective participation in globally distributed collaboration using email? Two subsidiary research questions follow: (1) What discernable patterns of cultural variation are evident in the email messages, and (2) What is the effect of cultural variation on the contribution of Civil Society during the following stages of the decision-making process: (a) problem identification, (b) proposal making and generation of ideas, (c) response to ideas and deliberation, and (d) solution. To answer these questions, we will apply Edward Hall’s (1976) intercultural communication theory as the primary lens. Specifically, we will employ a cultural dimension called “context” which explains the variations in terms of high-context-versus-low context. Other literature in this domain will also be used to explore the various aspects of cultural impacts. The main objective of this paper is to propose a research design that uses content analysis to look at the World Summit on Information Society (WSIS) public archival email messages. From this source material, we will apply intercultural communication theory in order to provide descriptive statistical analysis and in-depth descriptions for each of the decision-making stages described above, from a cultural stance. At the completion of this study, we hope to be able to demonstrate specific impacts that high context and low context cultural backgrounds have on globally distributed collaboration, and to suggest some fertile areas for future research such as how to minimize the different cultures’ drawbacks and maximize their positive advantages to facilitate globally distributed collaboration.
Designing Vivaldi Antenna with Various Sizes using CST Software
Lecture Notes in Engineering and Computer Science , 2011,
Norhayati Soin,Burhanuddin Yeop Majlis
Journal of Physical Science , 2006,
Abstract: This paper presents the results of simulation study on the effect of the temperature and concentration of the kalium hydroxide (KOH) etchants on the corner-undercutting phenomenon with respect to the formation of the silicon (100) corrugated diaphragm using KOH anisotropic etching. The Intellisuite process simulation software has been used in this study. Based on the geometrical etched structure of the convex corners and the emergent of the new silicon planes, the convex corner-undercutting phenomenon is found to be much more pronounced with increasing temperature and decreasing concentration of the KOH etchants.
Desulphurization of Transportation Fuels by Per-Formic Acid Oxidant Using MoOx Loaded on ZSM-5 Catalyst  [PDF]
Waqas Ahmad, Imtiaz Ahmad
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.512011
Desulphurization of model and real oil samples was investigated using performic acid as oxidant assisted by air as co-oxidant. The catalysts used were Mo-oxide supported on ZSM-5 zeolite, which was synthesized in the laboratory and characterized by FT-IR, XRD, SEM and SSA analysis. In case of model oil, the optimum condition determined for complete oxidation of all the model compounds including thiophene, DBT and 4,6-DMDBT were; 60?C, 60 min, ambient pressure and air flow rate of 100 mL/min. The oxidation reactivity decreased from 4,6-DMDBT to DBT and thiophene, which was found to follow pseudo first order kinetics. The real oil sample used in the study included untreated naphtha (NP), light gas oil (LGO), heavy gas oil (HGO) and Athabasca bitumen (Bit.). In case of NP and LGO the sulfur removal of above 78% was attained whereas in case of HGO and Bit. samples about 60% of desulfurization was achieved.
Intelligent City and Information-based Society: Implementation Based on and the Social Impact Indicators
Norhayati Abd. Mukti,Jalaluddin Abd Malik
Asian Journal of Information Technology , 2012,
Abstract: Intelligent city and information society concepts represent two vital and related applications in succeeding the developing of the city of 21 century. Intelligent city is equipped with infrastructure and infostructure technology, and mechanical technology. However. Intelligent city is impossible to be established if its population does not possess any characteristics of information society`s utilization and manipulation of information and information technology benefits for the peace of life. For example, electronic government is one of the applications which manipulates information and information technology benefits. Generally, information society that applies the electronic government possesses higher potential and motivation in all aspects of development. The aspect of facilities (technoware), database creation and information utilization (infoware) for the peace of social and economic, individual organization and culture (orgaware), positive minded (mindware), and strong social relation locally and globally. All those aspects become free indicators that provide indication and value to the characteristics or information society, from homo sapiens to homo intelligent (information based society) which depend on main indicators such as data, information knowledge, vision and wisdom. Basically, information and communication technology (ICT) and aspect of cognition support this potential. Thus, the objective of this paper is to analyse and illustrate the social impact of information society indicators (as mentioned above) in Malaysia. The Petagon method (Nijkamp & Pepping 1998), the INEXSK method (Mansell & When 1988), the techno economic method (Asian and Pacific Centre for Transfer Technology 1988) and the Johoko-Shakai index method (Ito 1980) are applied in order to the background of information society in Malaysia.
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