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Register a new userTypes, Synthesis, Sensing, Properties and Horizons
البوليميرات أنواعها، اصطناعها، خصائصها المحسة، و آفاقها المستقبلية
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Damascus University مقالة
Publication date
1999
fields
Physics
and research's language is
العربية
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Shamra Editor
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إن ظهور البوليميرات الحاصلة من ارتباط عدد كبير من الوحدات البنيوية أو المونوميرات المتماثلة على شكل سلاسل قد أضرم واحدة من أهم الثورات الصناعية في القرن العشرين. فالبوليميرات، بالإضافة الى المقاومة و اللدانة اللتين تضاهي بهما المعادن، فإنها تتفوق على هذه الأخيرة بالكثير من المزايا المهمة، فهي أخف منها، و تصنيعها أسهل، و سعرها العائد أخفض بكثير. و قد غزت البوليميرات حاليًا حياتنا اليومية: من السلع الاستهلاكية الأكثر شيوعًا الى أكثر التطبيقات تطورًا في قطاعات الفضاء و الملاحة الفضائية و استخدامها كصنانير جزيئية في اصطناع الأدوية و في تصعيد التفاعلات الكهركيميائية، و في الترشيح بالأغشية المدعومة. و في كيمياء الاستدال intercalation و في المحسات الكيميائية و الحيوية، و في التلاؤم الحيوي biocompatibility و في الترانزستورات العضوية و غيرها.
The evolution of Polymers which are produced by the binding of many structural units, i.e. monomers in series, has led to one of the most important revolution in the twentieth century. Besides their resistive and plastic properties which match those of metals, they are better than those in many characteristics as they are lighter, cheaper and above all easier to manufacture. Polymers are in every day life usage, starting from consumptional commedities (containors) through the most developed applications such as in space sectors and space navigation, and as molecular lock –and- key elements in medicine and chemical reaction activation and filtering, in addition to their use in intercalation chemistry and in biological sensors, biocompatibility and organic transistors among others.
References used
A. J. Nozil, Annu. Rev. Phys. Chem1978
H. Gerischer, J. Vacuum Sci. Technol1978
C. R. Fincher, Jr., M. Azoki, A. J. Heeger, & A. G. MacDiarmid, Phys. Rev. B1979
rate research
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Tow compounds have been synthesised: tetra butyl ammonium
alginate and dodecanoate sodium alginate ester.
The synthesis of compound (1) by transferring
sodium alginate to Alginic acid and then adjusted by tetra-butyl
ammonium hydroxide. The comp
ound (2) was synthesised from
tetra-butyl ammonium alginate according to Fisherest erification,
between tetra-butylammonium alginate and dodecanoic acid and
using (Amberlyst-15) as a hetrogeneous acid catalyst, and then the
product react with sodium carbonate.
Thick Films have been prepared by the chemical painting method from Tungsten Oxide nanopowdersas the source compound, which are prepared by milling in a high energy ball mill for variousspans of time (1-18h) on cleanedglasssubstratesunder limited the
rmal conditions. The temperature of the films have been changed from 25°C to 350°C. The films have been investigated for their sensing properties relating to 100 ppm ethanol vapor adsorption, using the (I–V) characteristics.The activation energy Ea for deposition films is deduced from the Arrhenius equation. The effect of the grain size and the thermal conditions on the sensing properties of the WO3thick films to ethanol vapor adsorption, as well as the correlations between The electrical conductivity of the WO3 thick films and the grain size of the material films are reported.The response time for films which have particle size about 70.54nm is defined at 300°C.
إن إنتاج الطاقة محليا له دور مضاعف في الاقتصاد أوّله تأمين متطلباته من الخدمات الطاقية المتنوعة، و ثانيا تكوين أحد أهم مصادره التمويلية في حال تحقيق فوائض في ميزان الطاقة. هذا ما انطبق بالفعل على النفط السوري خلال العقود السابقة إذ لعب دوراً استراتيج
ياً في الاقتصاد السوري. و لكن تتهدد الصناعة الطاقية في سورية اليوم بفقدان دورها هذا و ذلك نتيجة نهاية حقبة الفائض النفطي. هنا يقوم البحث على دراسة تطورات الصناعة النفطية في سورية و تأثير العجز النفطي على دور هذه الصناعة في التزود الطاقي من جهة، و في دعم توازنات الاقتصاد السوري من جهة أخرى. و من خلال تحليل الإمكانيات التي يتمتع بها الاقتصاد السوري و مصادر الطاقة الكامنة في سورية أمكن وضع استراتيجيات بديلة يمكن تحقيقها من خلال حزمة سياسات و إجراءات متكاملة. و خلص البحث إلى نتيجة مفادها أن نهاية النفط السوري قد تكون بداية للتفكير و العمل على إنشاء صناعة طاقية أكثر تطورا و استدامة في الاقتصاد في حال أحسن إدارة الموارد المتوفرة و استثمرت و استخدمت بالكفاءة المطلوبة.
Khans constitute one of the most important buildings throughout history, because of
their important role in the economic life.
They were marked by the enormity of construction, area, and also by details and
architectural elements either in the uni
que forms of gates, the interior spaces, courtyards
and openings internal windows and doors.
Khans gates formed unique architectural panels of beauty and richness by their
decoration. They formed an important subject worthy of studying and research.
Khans flourished significantly as Aleppo was one of the most important commercial cities
throughout history, because of its important geographical location, something which
distinguished it from other cities., especially during the Ottoman era, which saw the
construction of more than fifty Khans inside the city. These khans were established during
different periods of the Ottoman era, which seem similar in the general plan, but different
in details depending on the period of construction. This resulted in different models with
different details, as reflected in the varied forms of gates in size, decoration and
architectural details.
Khan gates in the sixteenth and seventeenth centuries were marked by the big
dimension, the intensity of motifs, and rich architectural details influenced clearly by the
Mamluk architecture.
In comparison, during the eighteenth and nineteenth centuries seemed more simple,
less massive than its predecessors, and even devoid of decoration.
The effects of European architecture were clear on the gates of Khans in the end of
the Ottoman era in the early twentieth century.
As a result, khans gates in Aleppo during the Ottoman era waere characterized by
diversity in size, configuration and architectural details, which must be recognized in any
restoration project, in order to preserve the original features and the characteristic of these
monuments.
This study has been performed in Agriculture Research Directorated Labs, Ministry of
Science and Technology/Iraq, aimed to use different formulations of weaning food
contained different concentrations of black rice flour, brown rice, peas and oat c
hips. Some
physical treatments like cleaning, peeling and milling to rice and and germination, chard,
peeling, drying and milling to peas were used to make these four formulations, which were
chosed depended on chemical analysis (moisture, protein, ash, fiber, carbohydrate, fat and
energy) in addition the estimation of some minerals (Ca, Fe and Zn) comparing with
recommendation of FAO weaning food and functional properties; like bulk density (BD),
foam capacity (FC) and swelling power (SP). Sensory evaluation was also conducted.
suggested questions
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