Growth of 1D TiO2nanostructures on Ti substrates incorporated with residual stress through humid oxidation and their characterizations.

Different Ti substrates, such as particles (as-received and ball milled), plate and TEM grid were oxidized for the growth of one dimensional (1D) TiO2nanostructures. The Ti substrates were oxidized for 4 h at temperatures of 700 °C-750 °C in humid and dry Ar containing 5 ppm of O2. The effects of residual stress on the growth of 1D TiO2nanostructures were investigated. The residual stress inside the Ti particles was measured by XRD-sin2ψtechnique. The oxidized Ti substrates were characterized using field emission scanning electron microscope equipped with energy dispersive x-ray spectroscope, transmission electron microscope, x-ray diffractometer and x-ray photoelectron spectroscope. Results revealed that humid environment enhances the growth of 1D TiO2nanostructures. Four different types of 1D morphologies obtained during humid oxidation, e.g. stacked, ribbon, plateau and lamp-post shaped nanostructures. The presence of residual stress significantly enhances the density and coverage of 1D nanostructures. The as-grown TiO2nanostructures possess tetragonal rutile structure having length up to 10µm along the 〈1 0 1〉 directions. During initial stage of oxidation, a TiO2layer is formed on Ti substrate. Lower valence oxides (Ti3O5, Ti2O3and TiO) then form underneath the TiO2layer and induce stress at the interface of oxide layers. The induced stress plays significant role on the growth of 1D TiO2nanostructures. The induced stress is relaxed by creating new surfaces in the form of 1D TiO2nanostructures. A diffusion based model is proposed to explain the mechanism of 1D TiO2growth during humid oxidation of Ti. The 1D TiO2nanostructures and TiO2layer is formed by the interstitial diffusion of Ti4+ions to the surface and reacts with the surface adsorbed hydroxide ions (OH-). Lower valence oxides are formed at the metal-oxide interface by the reaction between diffused oxygen ions and Ti ions.

Comparative Study between Conventional Method and Endonasal Endoscopic Resection of Juvenile Nasopharyngeal Angiofibroma.

Juvenile Nasopharyngeal Angiofibroma (JNA) is an uncommon, benign and extremely vascular tumour which accounts for 0.05-0.5% of all head and neck tumours. Now a day, endoscopic excision is a preferred surgery for early cases. This study was done with the aim to compare the outcomes and complications between endoscopic and conventional surgery of JNA. This cross sectional observational study was conducted in the Department of Otolaryngology & Head-Neck Surgery at Mymensingh Medical College Hospital, Mymensingh and Bangabandhu Sheikh Mujib Medical University, Dhaka from 8 March 2014 to 7 March, 2015. A total number of 20 cases were purposively selected and patient with intracranial extension were excluded from the study. Data was analyzed with SPSS software. Among the 20 patients, maximum 18(90%) were in 2nd decade, age was ranging from 11-33 years, mean 16.17 years. Maximum patients 13(65%) came with nasal obstruction and epistaxis and majority 13(65%) of them were in stage II. Endoscopic excision was done in 12(60%) cases and conventional surgery was done in 7(35%) cases. Mean hospital stay of endoscopic and conventional group was 4.62 vs. 10.23 days. Mean blood loss and mean operative time were 528.12ml vs. 1050ml and 2 hours 17 minutes vs. 3 hours 28 minutes respectively. Per-operative and postoperative complication were more (53.85%) in conventional surgery group. Endoscopic excision of nasopharyngeal angiofibroma is more preferable due to less operative time, less hospital stay, less per-operative blood loss and less complications. But in advanced cases conventional surgery and combined surgery is preferred.

Magneto-structural coupling in [Formula: see text].

[Formula: see text] compound is well Known to show the frustration of the spin structure. At 12 K, [Formula: see text] distorts to break symmetry of the degenerated frustrated spin states by the spin-Peierls-like phase transition, accompanying with the antiferromagnetic ordering. On the other hand, [Formula: see text] undergoes a Jahn-Teller phase transition at a temperature of 310 K, differing from the low temperature ferrimagnetic transition temperature [Formula: see text] of about 60 K. It is also reported that [Formula: see text] shows another magnetic phase transition at about 30 K. These two phase transitions accompanying with the lattice change can be understood by the magneto-elastic interactions. Two interactions, the Jahn-Teller interaction and the spin-Peierls-like interaction are co-exist in [Formula: see text] system. In this report the [Formula: see text] compounds with x = 0.8, 0.6 and 1 are investigated by the X-ray diffraction measurements. From these measurements the crystal structures are determined. The full width at half maximum and integrated intensity give the fruitful information for magnetic elastic interactions.

Valvular heart disease in pregnancy: maternal and fetal outcome.

The aim of this study was to evaluate the maternal and fetal outcome of pregnancy in Valvular Heart Disease (VHD). A better understanding of the effects of valvular abnormalities on pregnancy outcome is of value for risk assessment and the design of a therapeutic plan from the available information of a series of patient. A multicenter prospective study was carried out over a period of 5 years (2005-2009) involving 60 pregnant patients with valvular heart disease. Thirty eight patients (64%) had single valve involvement and mitral stenosis was the most predominant lesion (50%). Ten patients (16.7%) had undergone interventional and surgical correction prior to the pregnancy. Fourteen (24%) patients were identified as a NYHA class III-IV. Women with VHD had 8.35% pulmonary edema, 15.03% developed different types arrhythmia. The incidence of preterm birth and small for gestational age newborn was 11.69% and 13.36% respectively. There was one (1.67%) maternal death. Pregnancy in women with valvular heart disease is associated with remarkable unfavourable effect on maternal and fetal outcome which are related to severity of disease.

Anesthetic and surgical factors affecting open heart surgery patients leading to cerebrovascular accident--retrospective study at King Khalid University Hospital.

Stroke after coronary bypass grafting (CABG) is often disabling. The incidence of ischemic stroke may approach 3% to 5%. Several risk factors have been identified including previous history of stroke, prolonged cardiopulmonary bypass time, and postoperative atrial fibrillation. Retrospective study during the period 1992-1995 was undertaken to determine the incidence, risk factors of neurological deficit after open-heart surgery at King Khalid University Hospital, Riyadh, Saudi Arabia. There were 350 patients who were subjected to CABG, 10 patients (2.8%) were found to suffer from cerebrovascular accidents (CVA) following open-heart surgery. In 18 patients, the complaint lasted more than 24 hours (stroke), while 2 patients developed transient ischemic attacks (TIA). Five factors were found to be associated with increased risk of post cardiac surgery CVA. These factors are postoperative atrial fibrillation, carotid bruit, past history of heart failure, past history of CVA and smoking. The authors concluded that it is necessary to start a prospective study to verify the area of improvement with regards to technique, selection of patients and mode of perfusion during cardiopulmonary bypass (CPB).