research centers


Search results: Found 3

Listing 1 - 3 of 3
Sort by

Article
Preparation of Nd – Fluoride Laser Glass and Investigation of its Characteristics

Authors: Ziyad H. Rasheed --- Saad S. Rahmatallah
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2009 Volume: 15 Issue: 1 Pages: 3537-3552
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

Fluorophosphate neodymium laser glass has been prepared by discontinuous melting technique. Special melting and casting conditions were followed to prevent devitrification of glass samples. Furnace melting followed by slow cooling resulted formation of non vitreous glass. Problems of high viscosity melt and incomplete solubility and immiscibility of glass components were encountered by adjusting composition of glass components. X-ray diffraction analysis of the prepared glass samples proved the formation of amorphous phase. The prepared Nd – fluoride glass has low refractive index which is an important parameter for high power laser application. Optical properties of Nd – fluoride glass samples were investigated. UV – visible spectra showed almost total absorbance of light at wave length below 400 nm, while in the visible range a typical spectrum of Nd3+ ions covers the entire range. Infra – red spectral properties of these samples were studied. Transmission of the glass was found to be dependent on neodymium concentration.

زجاج ليزر النيودميوم الفلوروفوسفاتي تم تحضيره بطريقة الصهر الغير مستمر. وقد اتبعت ظروف خاصة لعمليتي الصهر و الصب (القولبة) لمنع حدوث ظاهرة التبلور في نماذج الزجاج. عند إجراء عملية الصهر في الفرن يتبع ذلك التبريد البطئ لوحظ حدوث ظاهرة التبلور(اللازجاجية) في نماذج الزجاج. تم معالجة مشكلتي اللزوجة العالية للمنصهر وعدم الذوبانية الكاملة والامتزاج التام لمكونات الخليط الزجاجي بالسيطرة على مكونات الخليط الزجاجي. أظهرت نتيجة الفحص بطريقة حيود الأشعة السينية إن النماذج الزجاجية المحضرة عشوائية التركيب والتكوين. إن نماذج زجاج النيودميوم- الفلوريدي المحضرة كانت تتميز بانخفاض معامل الانكسار الضوئي وهو شرط مهم في تطبيقات زجاج القدرة العالية. الخواص الضوئية لزجاج النيودميوم- الفلوريدي جرت دراستها حيث تبين إن الضوء يمتص كليا في منطقة الطول ألموجي الأقل من 400 نانومتر من الطيف المرئي – فوق البنفسجي بينما في منطقة الضوء المرئي فان طيف ايون النيودميوم يغطي غالبية المدى من الطول ألموجي. أما الخواص الضوئية للزجاج في منطقة تحت الحمراء فقد تمت دراستها حيث وجد إن نفوذية الضوء تعتمد على تركيز النيودميوم وبدرجات مختلفة وحسب الطول ألموجي.


Article
Water sorption of newly formulated resin-modified and conventional glass ionomer cements

Authors: Shatha S.Al-Ameer --- Saad S.Rahmatallah --- Monadle R. Hadi
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2010 Volume: 22 Issue: 4 Pages: 28-31
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

ABSTRACT
Background: Chemical bonding of glass ionomer cements to tooth structure may be affected by dimensional
changes associated with water absorbed by the material when it is in service inside the oral environment. The aim of
this work was to measure the amount of water absorbed by new formulated cements and compare it with cements
with old formula and two commercial cements.
MATERIALS AND METHODS: Four types of cements were prepared, two were resin-modified light-cured(1 and 2)and
two were conventional chemical-cured (4 and 5). Two commercial cements were used, the first was light-cured
cement 3 (Vivaglass) and the second was chemical-cured cement 6 (Nikang). Five specimens with 9mm diameter
and 4mm height were produced for each type of cement. The weight of each specimen was recorded after 24
hours before immersing in distilled water using very sensitive weight measuring balance with a precision ± 2 mg. A
desiccator was used to absorb water from the specimen material for 24 hours. Then the weight of each specimen
was recorded. The specimens were immersed in 20 milliliters of distilled water at room temperature (25ºC ± 2). The
weight of each specimen was then recorded after different immersing times of five minutes, 10 minutes, 15 minutes,
30 minutes, 60 minutes, one day, three days, one week, 10 day, and two weeks, until no more water absorbed. The
value of water sorption was calculated and the final value was rounded to the nearest 0.1mg/cm2.
RESULTS: Resin modified cements showed higher values of water sorption than those of conventional types of glass
ionomer cements. The highest value of short-term water sorption test was recorded for cements (5) followed by
cement (2). While the lowest value of water sorption was recorded for cement (3)
CONCLUSSION: Resin-modified cements absorb more water than conventional cements. Changing the powder
formula had no clear effect on water sorption, while the resinous components of the liquid had direct effect on
water sorption of the tested cements.
Key words: Water sorption, resin-modified glass ionomer cement, conventional glass ionomer cement. (J Bagh Coll
Dentistry 2010;22(4):28-31).

Keywords


Article
Fluoride release from newly formulated resin-modified and conventional glass ionomer cements

Authors: Shatha S.Al-Ameer --- Saad S.Rahmatallah --- Monadle R. Hadi
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2010 Volume: 22 Issue: 4 Pages: 32-35
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

ABSTRACT
Background: Glass ionomer cement has been used as a restorative material for its chemical bonding to tooth
structure and fluoride release to the surrounding tooth structure. The aim of this study was to see if increasing the
fluoride contents in the cement powder increases the amounts of fluoride released from the set cement.
Materials and Methods: Two types of cements were prepared with increased fluoride contents: cement (1) as lightcured
resin-modified and cement (2) as chemical-cured conventional glass ionomer cements. Two commercial
cements were used for comparison, cement (3) was light-cured (Vivaglass), and cement (4) was chemically-cured
(Nikang). Five specimens for each type of cement were used as discs of 6mm diameter × 3mm height. The
specimens were immersed in artificial saliva solution for 1 day, 1week, 2 weeks, 1 month and 2 months. The amount
of fluoride ions released in the saliva solution was then measured using fluoride ion specific electrode connected to
an ion- analyzer.
Results: The experimental cements (1 and 2) showed increased amounts of fluoride release than commercial
cements (3 and 4). The total amount of fluoride release from the resin-modified cement (1) was more than that of
conventional cement (2) through the time of test.
Conclusion: Fluoride release of prepared cements was higher than that of commercial cements. Increasing fluoride
contents within the cement formula led to increased fluoride release of the set cement.
Key words: Fluoride, resin, glass ionomer cement. (J Bagh Coll Dentistry 2010;22(4):32-35).

Keywords

Listing 1 - 3 of 3
Sort by
Narrow your search

Resource type

article (3)


Language

English (3)


Year
From To Submit

2010 (2)

2009 (1)