Nguyen Ngoc Trung

Single phase Si1-xGex nanocrystals and the shifting of the E1 direct energy transition.

We report preparation and characterization of Si1-xGex alloys with varied composition x of a large range from 0-1. The materials have been obtained by co-sputtering, followed by a heat treatment process at 600, 800, and 1000 °C for 30 min in a nitrogen gas atmosphere. X-ray diffraction data have revealed the formation of single-phase nanoparticles in the face-centered cubic (FCC) structure of Si1-xGex alloys. We found that lattice constant a of the Si1-xGex alloys increased linearly with the composition parameter x. Average diameters of the single-phase nanoparticles were estimated to be between 3-10 nm. Further evidence of FCC single-phase [Formula: see text] nanoparticles has been obtained by high resolution transmission electron microscopy. From absorption spectra, the gradual shift of the direct phononless transition identified for the E1 point in the Brillouin zone of bulk Ge is observed in single-phase Si1-xGex nanoparticles as a function of the composition parameter x.

Thoracic Paravertebral Analgesia for Treatment Blunt Chest Trauma withMultiple Rib Fractures

Multiple rib fracture (MRF) causes severe pain that compromise respiratory mechanics. We evaluated the efficacy of thoracic paravertebral block with bupivacaine -fentanyl mixture in patients with unilateral MRF. The study was carried out on 172 blunt chest trauma patients in prospective nonrandomized case series. An initial bolus dose of 0.3 ml/kg of bupivacaine 0.25% plus fentanyl 2 μg/ml was used following by continuous infusion with 0.1 ml/kg/h of bupivacaine 0.125% plus fentanyl 2 μg/ml. Pain severity was assessed by visual analogue scale (VAS) at rest and during coughing; bedside spirometry was measured 5 times in 3 consecutive days after paravertebral block. Traffic accidents (69.1%) was major reason for blunt chest trauma; the number of ribs fracture ranged from 3-5 (76.1%) and 6-8 (23.9%). The rate of hemothorax, pneumothorax and the combination hemothorax-pneumothorax were 64.5%, 7.6% and 27.9% respectively. There was significant improvement in pain score at rest and during coughing, respiratory rate, FVC and FEV1 (p<0.05) 30 min after initial bolus dose, which were sustained during continuous thoracic paravertebral infusion 72 h (p<0.05). The rate of analgesic rescue by paracetamol infusion was 6.4%. No patient had respiratory depression or respiratory failure or signs of local anesthetic toxicity. The result shows that thoracic paravertebral analgesia with bupivacaine and fentanyl provided a good efficacy for pain management in patients with unilateral MRF.

Investigation of the Transformation of a Modified Iron Oxide Structure During Redox Reaction

Iron oxides can be used for the storage of hydrogen based on their redox reaction. Iron oxides were synthesized by the sol-gel method was a structure transformation of maghemite γ-Fe2O3 into hematite α-Fe2O3 during calcinations process could be observed. The addition of a Mo6+ cation by the preparation method results in the substitution of Mo6+ into the Fe2O3 structure and formation of Fe2(MoO4)3. There was a formation of two crystalline phases Fe2O3 and ZrO2 separately incase of the addition of Zr4+cation into Fe2O3.During redox reaction, the structure of Fe2O3 was converted into Fe and regenerated Fe3O4. There was a transformation of Fe2 (MoO4)3 into Fe2Mo3O8 phases after reduction. However ZrO2 was did not change its structure during redox reaction. The Zr-Fe2O3 very easy to be reduced into Fe and convenience formed hydrogen in the oxidation.

Effect of Fe doped on superhydrophilic properties and antibacterial activity of TiO2 thin film preparared by sol-gel dip coating

In this paper, we present some studies Fe undoped and doped on TiO 2 thin films is prepared by sol-gel dip coating technique. Effects of doped iron on the characteristics of the films were studied using RAMAN spectra. Morphology surface of thin film are investigated by FESEM. Superhydrophilic properties and antibacterial activity of modified TiO 2 films were evaluated by studying under visible light and UV irradiation. The superhydrophilic efficiency of modified TiO 2 films by this method is affected by the concentration of doped iron. Keywords: Sol-gel dip coating, Superhydrophilic, Antibacterial, Visible light, UV irradiation.

Behaviour investigation of hematite nanorods synthesised by hydrothermal method use in hydrogen fuel storage

For the first time, hematite nanorods were successfully synthesised using iron nitrate precursors in the presence of cation SO4−2. This is also the first time that an investigation into hematite nanorods behaviour for hydrogen fuel storage has been carried out. Microspheres constructed with α-FeOOH nanorods were synthesised via a novel hydrothermal method using a mixture of Fe(NO3)3 · 4H2O and Na2SO4 as the initial material. The α-FeOOH was transformed into hematite (α-Fe2O3) nanorods through an annealing process at 600°C for 2 h. The influence of different anions on the formation of hematite α-Fe2O3 nanorods was investigated. Experimental results proved that the addition of Na2SO4 solution controlled the morphology of α-Fe2O3. Its structure and morphology were investigated using XRD, SEM and Raman techniques. The kinetic curve of hydrogen generation of some hematite morphology samples was examined by redox cycle and the hydrogen fuel was formed by oxidation with water vapour. Although the nanorod morphology of hematite samples was damaged during redox cycles, the samples demonstrated high activity for hydrogen generation in comparison with precipitation and sol gel samples. The ratio of H2/Fe of nanorod samples for two redox cycles was 1.91% and 1.76%, respectively. Thus, hematite nanorods are a promising material for storage of hydrogen fuel.