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- 저자 : Alkhalaf, Salem (검색결과 5 건)
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( Alkhalaf Norah. S. ),김석찬 ( Seok Chan Kim ) 한국공업화학회 2018 공업화학 Vol.29 No.3
DMT 생산과정의 부산물로서 폐기 처리되어 왔던 methyl 4-formylbenzoate (MFB)를 출발 물질로 하여 고급 형광 증백제 family와 동일한 4,4’-di((E)-styryl)-1,1’-biphenyl 기본 골격을 갖고 aromatic ester가 도입된 새로운 형광 증백제 (fluorescent whitening agent) 후보 물질 6종을 합성하였다. 후보 물질 6종은 MFB 및 그의 유도체와 tetraethyl biphenyl-4,4’-diylbis(methylene)diphosphonate와 Wittig-Horner 반응을 이용하여 합성하였다. 합성된 6종에 대하여 형광증 백제로의 가능성을 확인하기 위하여 UV 스펙트럼을 기록하여 흡광 계수를 얻었으며, 6종 모두 전반적으로 기존 상용제품(log ε 4.85)과 유사한 몰 흡광 계수(log ε 4.59~5.00)를 보여주고 있다. 특별히 화합물 디메톡시 페닐그룹을 갖는 16, 17은 기존 상용 제품보다 우수한 몰흡광 계수를 나타내고 있어 상용화를 위한 현장 테스트를 진행할 예정이다. Methyl 4-formylbenzoate (MFB), a by-product of the DMT production process, which has been disposed, was used as a starting material for the synthesis of six new fluorescent whitening agent’s candidates with 4,4’-di((E)-styryl)-1,1’-biphenyl skeleton attached with an aromatic ester, the same as that of the commercial product family. All candidates were synthesized by the reaction of MFB, and its derivatives with tetraethyl biphenyl-4,4’-diylbis(methylene)diphosphonate using Wittig-Horner reaction. UV spectra for all candidates were recorded and the data were used for calculating the molar absorptivity in order to confirm the usability as a fluorescent whitening agent. All of them showed overall molar extinction coefficients (log ε 4.59~5.00) similar to those of conventional commercial products (log ε 4.85). In particular, compounds 16 and 17 having a dimethoxyphenyl group exhibited a molar extinction coefficient superior to those of conventional commercial products, and thus a field testing for commercialization will be conducted.
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Matrix Formation in Univariate and Multivariate General Linear Models
Arwa A. Alkhalaf International Journal of Computer ScienceNetwork S 2024 International journal of computer science and netw Vol.24 No.4
This paper offers an overview of matrix formation and calculation techniques within the framework of General Linear Models (GLMs). It takes a sequential approach, beginning with a detailed exploration of matrix formation and calculation methods in regression analysis and univariate analysis of variance (ANOVA). Subsequently, it extends the discussion to cover multivariate analysis of variance (MANOVA). The primary objective of this study was to provide a clear and accessible explanation of the underlying matrices that play a crucial role in GLMs. Through linking, essentially different statistical methods, by fundamental principles and algebraic foundations that underpin the GLM estimation. Insights presented here aim to assist researchers, statisticians, and data analysts in enhancing their understanding of GLMs and their practical implementation in diverse research domains. This paper contributes to a better comprehension of the matrix-based techniques that can be extended to GLMs.
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Management of the energy harvesting for MEMS/NEMS via newmark current method
Shang, Kun,Shan, Huafeng,Alkhalaf, Salem,Marzouki, Riadh,Khadimallah, Mohamed Amine Techno-Press 2022 Advances in nano research Vol.12 No.6
The free and forced vibration in addition to electric energy harvesting of a piezoelectric disk resting on two-parameter foundation modeled by modified couple stress as well as Kirchhoff plate theory is probed. The governing equations and boundary conditions are obtained using Hamilton's principle. Then, the free and forced vibration are solved using numerical solutions, generalized differential quadrature method (GDQM) and Newmark-beta method. The forced vibration is resulted from a base excitation load. Also, the possible voltage which can be harvested from this system is obtained using generalized integral quadrature method. The validity of the formulation and solution procedure is confirmed using a compassion study. The impact of parameters such as length effect, inner to outer radius ratio, and foundations parameters on the free and forced vibration as well as energy harvesting is investigated in detail. This paper can be a basis for future studies in the area of piezoelectric harvesters in small scales.
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Al-Jehani Hosam,Alhamid May Adel,Alkhalaf Yousef,Alabbas Faisal 대한신경중재치료의학회 2020 Neurointervention Vol.15 No.3
Free-floating thrombus (FFT) is a rare condition with unknown etiology as described by many case reports presented in previous literature. The patients usually present symptomatically while the other few patients remain asymptomatic and are usually discovered incidentally on computed tomography angiography (CTA). Most of the cases reported in the literature are of FFT in the internal carotid artery. We present a 59-year-old female as a case of FFT in the vertebral artery which was coincidently discovered on CTA in a patient initially presenting with an anterior circulation stroke. This case highlights the importance of early contrast-based vascular imaging in patients presenting with large vessel strokes that are cardioembolic in nature and the unique utilization of a direct aspiration first pass technique (ADAPT) for revascularization. Included herein an extensive review of the literature about the decision making in patients with FFT and a devised proposed practical approach to this entity.
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