Upgrading of bio-oil: Effect of light aldehydes on acetic acid removal via esterification

Since fast pyrolysis derived bio-oils are not a simple hydrocarbon mixture, but rather contain a variety of oxygenated compounds including acids and aldehydes, upgrading is required in order to use bio-oils as transportation fuels. Esterification is one of the attractive routes to convert acids contained in bio-oil to more desirable esters. Although organic acid esterification is a simple reaction, no work has been reported as to whether the presence of other reactive oxygenated compounds such as aldehydes affect the reaction. In this study of bio-oil model compounds, the impact of acetaldehyde and propionaldehyde on acetic acid esterification was investigated on organic–inorganic mesoporous silica functionalized with propylsulfonic acid groups. No impact of these two aldehydes on acetic acid consumption was seen at 100 °C, regardless of the concentration of ethanol used. However, at 70 °C and 50 °C, the conversion of acetic acid was observed to be lowered during the reaction in the presence of the aldehydes. When either of the aldehydes were present, the acetic acid conversion was about 6% and 28% lower than that in its absence at 70 °C and 50 °C, respectively. It appears that the more significant aldehyde impact on acetic acid conversion seen at the lower reaction temperatures was due to the esterification rate being slow relative to the rapid competitive acetalization rate of the aldehydes with ethanol.     

Probing chirality of a lipid tubular by confocal Raman microscopy

The chiral phospholipids 1,2-bis-(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9 PC) can self assemble into lipid nanotubules. This hollow cylindrical supramolecular structure shows promise in a number of biotechnological applications. The mechanism of lipid tubule formation was initiated by assembling of lipid bilayer sheets from amphiphilic solution. Upon cooling, small ribbons were detached from the sheets and rolled up into helical tubules. The lipid tubules obtained were 0.6-0.8 microm in diameter and approximately 50 microm in length. Raman spectra of individual polymerized lipid tubules were measured by focused laser excitation of 532 nm leading to intense and reproducible Raman spectra. The chirality of lipid tubules was investigated by atomic force microscopy (AFM) and confocal Raman microscopy. We report the Raman mapping images revealing helical tubular profiles of C=C stretching and C[triple bond]C stretching of lipid tubules. Circular dichroism property of lipid tubules has also been probed with a 532 nm laser.     

Lead associated caries development in children living in a lead contaminated area, Thailand

In an observational cross-sectional design, a sample of 292 children aged 6-11 years from two primary schools around a shipyard area, known to be an area contaminated with lead (from the industry), were examined to verify the cariogenicity of lead. The number of decayed and filled surfaces on deciduous teeth (dfs), and the number of decayed, missing, and filled surfaces on permanent teeth (DMFS), the salivary flow rate, pH, buffer capacity, oral hygiene, Lactobacillus spp. and mutans streptococci counts were recorded. The mean (range) of DMFS and dfs were respectively 1.3 (range 0-17) and 13.2 (range 0-45); and the geometric mean blood lead level (PbB) and SD were 7.2 and 1.5 microg/dl. The level of dfs, but not DMFS correlated with the blood lead level (R(s)=0.25, p=0.00 / R(s)=0.09, p=0.14). The odds ratio for DMFS>or=1 and dfs>5 for a doubling of PbB after adjusting for other factors were 1.28 (95%CI, 0.81-2.04; p value=0.35) and 2.39 (95%CI, 1.36-4.20; p value=0.004), respectively. The cariogenicity of lead is evident in deciduous teeth but not in permanent teeth for this age group.     

Translationally controlled tumor protein against apoptosis from 2-hydroxy-ethyl methacrylate in human dental pulp cells

2-Hydroxy-ethyl methacrylate (HEMA) is a major monomer released from resin-base dental restorative materials. HEMA is cytotoxic to pulp cells and leads to apoptosis. This study examined the effect of Translationally Controlled Tumor Protein (TCTP) against apoptosis from HEMA. TCTP from banana prawn (Penaeus merguiensis) was cloned and the protein was purified. It significantly increased the number of viable of HEMA-treated cells compared to HEMA-treated cells alone. Flow cytometry indicated the addition of TCTP at 10 μg/ml to 8 and 10 mM HEMA decreased the apoptotic cells from 20 to 10%. The proliferative property and anti-apoptotic activity against HEMA was concentration dependent. It was interesting that the added TCTP was not detected inside the cells and the native human TCTP was decreased after treated with HEMA and TCTP (20 μg/ml) + HEMA(10 mM) for 24 h. These results provided preliminary information, which may contribute to the development of less toxic dental materials.     

Chemical composition of enamel and dentine in primary teeth in children from Thailand exposed to lead

Enamel and dentine in teeth of children with high blood levels of lead were analyzed by means of secondary ion mass spectrometry (SIMS) and X-ray micro-analyses (XRMA) and compare with teeth from children with low blood levels of lead. The SIMS analysis revealed detectable levels of Pb in dentine close to the pulp. The XRMA analyses could not detect any lead. There were no differences found in lead level in enamel of high lead level exposed teeth from low level exposed. The results confirm that children with high blood levels of lead have an uptake of lead in dentine close to the pulp.     

Effect of arc current on characteristics of nanocarbons prepared by cryogenic arc discharge method

A variety of nanocarbons (nanohorns, nanoflowers and nanoclusters) could be prepared by arc discharge in cryogenic nitrogen with either graphite–graphite or iron–graphite electrodes manipulated by a strategy of automatic electrode delivering. Based on local thermal equilibrium assumption, magneto-hydrodynamic equations were taken into account for estimating the arc power efficiency of 60–84%, depending on the electrode combination. The effects of arc current on the morphology and yield of nanocarbons were investigated within a range of 75–150 A. Transmission electron microscopic analyses revealed that the synthesized product consisted of single-walled carbon nanohorns and multi-walled carbon nanoflowers with nominal diameters of 100–200 nm when graphite–graphite electrodes were employed but nanoclusters containing Fe nanoparticles inside carbon nanoshells with smaller size of 70–120 nm were mainly synthesized by iron–graphite electrodes subject to arc discharge in cryogenic nitrogen.     

Simultaneous HPLC–DAD quantification of vitamins A and E content in raw,pasteurized, and UHT cow’s milk and their changes during storage

An improved extraction and HPLC method for the simultaneous extraction and quantitation of retinol, α-tocopherol, α-tocotrienol, and β-carotene was developed to analyze commercial whole/semi-skim/skim samples of raw/pasteurized/UHT milk in transparent plastic/glass bottles and Tetra Brik? containers. The sample preparation method required prior saponification at 40 °C for 15 min followed by n-hexane extraction. An isocratic acetonitrile/methanol (65:35 v/v) mobile phase, C₁₈ analytical column, and UV detector were chosen for HPLC quantification. The liposoluble vitamin content in raw, pasteurized conventional/organic, and UHT milk ranged 0.055–5.540 (retinol), 0.135–1.410 (α-tocopherol), and 0.040–0.850 mg/L (β-carotene). No significant differences (p > 0.05) were observed on losses of retinol, α-tocopherol, and β-carotene content in UHT whole milk after 5 days at 4 °C in the dark. After 14 days at 4 °C in the dark, the contents of retinol, α-tocopherol, and β-carotene remained higher in milk with higher fat content and were higher in unopened containers. In UHT whole milk, samples containing 0.02 % NaN₃, retinol (33 %), and α-tocopherol (11 %) but not β-carotene (2 %) decreased significantly (p < 0.05).     

Mesoporous Silicon Nitride Synthesis Via the Carbothermal Reduction and Nitridation of Carbonized Silica/RF Gel Composite

Silicon nitride (Si₃N₄), a high-temperature structural ceramic, was synthesized in a mesoporous form by a simple approach. At first, silica/resorcinol–formaldehyde (RF) gel was formed via sol–gel polycondensation process, using resorcinol and formaldehyde as sources for porous RF structure and amino propyl trimethoxysilane as a precursor for silica. Pyrolysis of the dried gel at 250°C for 2 h following by at 750°C for 4 h resulted in silica/carbon composite that could be converted into mesoporous Si₃N₄ or Si₃N₄/silicon carbide composite via the carbothermal reduction and nitridation process at 1450°C. Significant increase in surface area of the products, comparing with that of the conventional Si₃N₄ granules, was observed. The content of silica in the starting composite was found to be a critical factor influencing both phase and porosity of the obtained product.