531 research outputs found
Geochemistry and Tectonic Setting of Neoproterozoic Rocks from the Arabian-Nubian Shield: Emphasis on the Eastern Desert of Egypt
The Neoproterozoic rocks of the Eastern Desert (ED) of Egypt represent the northwestern part of the Arabian-Nubian Shield (ANS), which was formed during the Pan-African orogenic cycle (950–450). Geochemistry of the different rock units has clarified their compositional variations, tectonic settings, and origins. The ages of these rock units were reported to predict the crustal evolution of the ANS. Island arc volcanic rocks and ophiolitic sequences formed between 700 and 800 Ma, and then, they were obducted in the earlier stage of the Pan-African orogeny. The post-collision stage was characterized by the emplacement of large masses of Dokhan volcanics (610–560 Ma) and shallow level A-type granites (610–550 Ma). Neoproterozoic ophiolites fall geochemically and tectonically into two separate groups: MORB-like ophiolites and SSZ ophiolites of fore-arc tectonic setting. Intra-oceanic island arcs and related inter-arc volcaniclastic sediments are followed by the incorporations of ophiolite fragments into the volcaniclastic matrix to form “ophiolitic mélange” through tectonic and/or concurrent sedimentary and tectonic processes. The “gneissic domes” that are metamorphic core complexes were previously interpreted to represent a pre-Neoproterozoic. However, recent age data argued that the ED gneissic rocks are juvenile in origin and Neoproterozoic. Granitoid rocks in the ED include older and younger types. Most of the older granitoids are of I-type character, displaying metaluminous, calcalkaline geochemical characteristics plot in the area of volcanic arc granites (VAG), whereas most of the younger granitoids are mainly alkaline of A-type granites and of within-plate tectonic setting (WPG). Nonmetamorphosed Dokhan volcanics and Hammamat molasse sediments formed during the final post-collisional phases
Work-Nonwork Factors as Explanatory Variables of Industrial Attitudes and Behaviour in a Developing Country: The Case of the Sudanese Blue-Collar Worker
The subject matter of this research project has been the attitudes and behaviour of the Sudanese industrial worker. The objective is to test the thesis that, given the novelty of the industrialization process in most of the developing countries, nonwork factors i.e. , workers' experience in the wider society, are more important in shaping attitudes to work than the immediate experience of it. This hypothesis was tested via exploring (i) the priorities, goals and preferences which the Sudanese industrial worker pursues in his employment, (ii) the importance of working in his life (his central life interests), his commitment to wage-employment and the ways in which these are related to his experience on the job, (iii) the similarities and differences workers may exhibit vis-a-vis their orientations and commitment to work along their skill levels and (vi) the ways in which workers' orientations and commitment to work are constrained by their social experience outside the work domain
Shapiro and parametric resonances in coupled Josephson junctions
The effect of microwave irradiation on the phase dynamics of intrinsic
Josephson junctions in high temperature superconductors is investigated. We
compare the current-voltage characteristics for a stack of coupled Josephson
junctions under external irradiation calculated in the framework of CCJJ and
CCJJ+DC models.Comment: 4 pages, Manuscript for Dubna-Nano 2012, submitted for Journal of
Physics:Conference Serie
Phenolic Compounds from Artichoke (Cynara scolymus L.) By-products and their Antimicrobial Activities
Cynara scolymus L. is a medicinal plant frequently used in traditional medicine for liver diseases. The aim of this study is to evaluate the antimicrobial activity of the different parts of Artichoke. Maximum antimicrobial activity was observed with methanolic extract of bound phenols for (bract and heart) against Gram negative bacteria. The MIC values for bound phenols from heart were (63?g/ml). Whereas, the bound phenols for bracts was ranged from (312 and 486?g/ml) against Gram negative and (486?g/ml) against Gram positive. Free phenols of the heart of artichoke showed the lowest MIC (204 to 206) ?g/mL for microorganism Gram positive and Gram negative. Therefore, this study indicate that the free phenolic extract from bracts of Cynara scolymus L. might be of interest within the developing market of nutritional ingredients and is capable of yielding nutritional supplements with antimicrobial activities. Key words: artichoke wastes, antibacterial effect
A Comparative Study on the Active Constituents, Antioxidant Capacity and Anti-Cancer Activity of Cruciferous Vegetable Residues
أجريت هذه الدراسة لتقييم كفاءة وفعالية مخلفات أربعة أنواع من خضروات العائلة الصليبية (البراسيكا) تم ستخلاصهم بمذيبين (الميانولي - المائي) وهم كاتالي البروكولي ، كرنب بروكسل ، القرنبيط ، الفجل الأحمر. وتم تقييم المستخلصات من حيث محتواها الكلي من المركبات الفعالة مثل الفينولات و الفلاڤونيدات والتانينات وڤيتامين سي واتعرف عليها بالـ HPLC ودراسة نشاطاتها المضادة للأكسدة بأكثر من طريقة مثل الـ DPPH· والـ Fe2+-chelating والـ Reducing power وكذلك دراسة كفاءتها في كبح جماح ومنع إنتشار وتكاثر ثلاثة أنواع من الخلايا السرطانية للإنسان علي النطاق المعملي مثل خلايا سرطان الكبد HePG2 و خلايا سرطان القولون HTC116 وخلايا سرطان الثدي MCF7. أظهرت النتائج أن المستخلص الميثانولي لمخلفات البروكولي وكرنب بروكسيل أعطي أعلي محتوي من المركبات الفعالة و أعلي نشاط مضاد للأكسدة في كبح جماح الشق الحر الـ DPPH· و وأعلي قدرات إختزلية ضد الحديديك الـ Reducing power. بينما أظهر المستخلص المائي لكل من كرنب بروكسيل والقرنبيط اعلى نشاط في عملية خلب الحديدوز الـ Fe2+-chelating. أكد تحليل HPLC للتعرف علي المركبات الفينولية الموجودة في مستخلصات مخلفات خضروات البراسيكا التي تم التعرف عليها أن المستخلص الميثانولي يمتلك كميات مرتفعة من الكاتشين والروتين والكيوماريك والبنزويك و الليتيولين. كما أظهر المستخلص الميثانولي لمخلفات كرنب بروكسيل تأثيراً مثبطاً و مانع للإنتشار وقاتل مع كافة أنواع الخلايا السرطانية وكان ذلك متبوعاً بالبروكولي والفجل الاحمر على التوالي. أكدت هذه النتائج أن مخلفات كرنب بروكسيل تحتوي على مركبات كيميائية فعالة يمكنها أن تمنع تكاثر الخلايا السرطانية. لذلك ، اقترحت هذه النتائج أن مخلفات خضروات البراسيكا يمكن إستخدامها كمضادات أكسدة قوية ومضادة لإنتشار الخلايا السرطانية وذلك في تطبيقات الصناعات الغذائية و الدوائية.This study is pointed out to estimate the effectiveness of two solvents in the extraction and evaluating the active ingredients and their antioxidant activity as well as anti-cancer efficiency. Therefore, residues from four different Brassica vegetables viz. broccoli, Brussels sprout, cauliflower, and red cherry radish were extracted using two procedures methods: methanolic and water crude extracts. Methanol extracts showed the highest content of total phenolic (TP), total flavonoids (TF), and total tannins (TT) for broccoli and Brussels sprouts residues. Methanolic extract of broccoli and Brussels sprouts residues showed the highest DPPH· scavenging activity (IC50 = 15.39 and 18.64 µg/ml). The methanol and water extracts of Brussels sprout residues showed the highest chelating activity (IC50 = 11.77 and 5.94 µg/ml) and exhibited the highest reducing power (EC50 =14.38 and 20.18 µg/ml) with broccoli respectively. The HPLC analysis of phenolic compounds confirmed that the methanol extract of all the residues examined possessed high amounts of catchine, rutin, cumaric, benzoic, and luteolin. The methanol extract at 100 µg/ml of Brussels sprouts residues displayed a rise cytotoxic effect on HePG2 (80.40%), MCF7 (75.49%) and HCT116 (22.74%) followed by broccoli and red cherry radish, respectively. This result confirmed that Brussels sprouts residue contain effective chemical compounds that can inhibit the proliferation of cancer cells. Therefore, these results proposed that those Brassica vegetable residues might be beneficial as a potent antioxidant and anticancer agents and strongly recommended as fixing in constituent's food applications and pharmaceutical industries
The behaviour of polyurethane foam beams reinforced with thin walled steel sections for use in bus structures
The thesis is directed to the theoretical determination of the
behaviour of rigid skin polyurethane foam beams reinforced with thin
walled steel sections. The aim is to enable the designer to predict
the behaviour of bus body structure during accident situations in order
to build safe buses.
A literature search has revealed that very little work has been
done in this particular field of research. Thus a preliminary test
programme was made to investigate the beam behaviour in bending
particularly at high deflection. The test results shown in Chapter 1
gave promising results for continuing the research.
Chapter 2 is directed to elastic analysis of composite beams. One
of the advanced methods to predict the elastic stiffness of sandwich
beams is the interfacial shear method. This assumes an interfacial
shear between the core and the faces of sandwich beams. So, by
considering a similar assumption, i.e. an interfacial shear between
the matrix and the reinforcement, an analysis was made to predict the
stiffness of composite beams. Although this method highly overestimated
the stiffness, it represents a good basis for the inelastic bending
analysis which is more important for the present study.
Chapter • 3 shows the inelastic bending analysis of composite beams.
This analysis is based on TIMOSHENKO and JAMES curvature area method.
The experimental verification of the theory is shown in Chapter 4.
The theory shows good agreement with the experimental results. The
shape of the reinforcement was optimised for uniaxial bending. This
optimum composite section showed a weight saving when it was compared
with equivalent energy absorbing rectangular steel tube.
Impact tests were made using a pendulum designed specially to test
cantilever beams at different speed and impact energies. The test
results are presented in Chapter 5. These results showed that the
composite beams behaviour is similar for both static and dynamic loading.
To compare the composite beam with the constituent beams, the
large deflection behaviour of thin walled channel section beams made of
thin sheet steel has been investigated. The experiments consisted of
cantilever bending tests with the beam loaded through the shear centre
and through the centroid. When loaded through the shear centre the
beam buckling took place in the compression flange at the root of the
cantilever. When loaded through the centroid however, it was noted
that the compression flange buckled at a fixed distance from the fixed
end. The general theory of thin walled beams developed by Vlasov was
applied to the problem and indicated that the maximum compression stress
at the free edge of the flange would be a maximum at some distance from
the fixed end. The value of the maximum compression stress obtained
by the general linear theory was small and its position did not coincide
with the experimental position. The Vlasov analysis has been modified
to include the increase in the twisting moment due to the lateral
deformation- of the beam along its length. Good agreement between the
modified theory and experiment both for the position of the maximum
compressive stress and for the twist of the cantilever at three points
along its length.
Because of the very low torsional stiffness of thin walled channel
sections, the small deflection theory is only applicable for small
bending loads applied through the centroid and the modified theory
should be used for practical loading cases.Ph
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