Effect of particle size on three dimensional printed mesh structures

Three dimensional printing is a unique technique that can print complex 3D structures that cannot be produced by other means, especially for rapid prototyping purpose. In this study, 3D mesh structures are created by three dimensional printing with four different TiNiHf powder sizes. Mesh structure green strength and surface smoothness are characterized in order to produce high quality 3D structures. Binder spreading time and spreading rate in the TiNiHf powders are measured in order to understand binder penetration difference in the mesh structures. The study shows that smaller TiNiHf particle size produces higher mesh structure green strength and surface smoothness, consistent with the observation that binder spreading is slower for smaller TiNiHf particles.     

Comparison of the Impact of γ-Oryzanol and Corn Steryl Ferulates on the Polymerization of Soybean Oil During Frying

Corn steryl ferulates (CSF), oryzanol, a combination of equal amounts of CSF and oryzanol, and ferulic acid were added to refined, bleached, deodorized, soybean oil at a concentration of 8.1–8.4 μmol/g oil, which corresponded to 0.5% (w/w) for the steryl ferulates. The rate of polymerized triacylglycerol (PTAG) formation was determined in three replicate, two-day frying experiments using a miniature frying protocol with potato cubes. Oryzanol and ferulic acid slightly inhibited PTAG formation on the first day of frying. However, the two treatments were not significantly different from the SBO control on the second day of frying. CSF and the combination of CSF and oryzanol significantly inhibited PTAG formation on both days of frying, but the combination was slightly more effective on the second day of frying. Tocopherol degradation in SBO with added oryzanol or ferulic acid proceeded more rapidly compared to the control. However, CSF and the combination of CSF and oryzanol appeared to protect tocopherols from degradation. In addition, CSF was more stable to frying compared to oryzanol, but when CSF and oryzanol were combined, CSF protected oryzanol from degradation.     

Identification of A/H5N1 influenza viruses using a single gene diagnostic microarray

In previous work, a simple diagnostic DNA microarray that targeted only the matrix gene segment of influenza A (MChip) was developed and evaluated with patient samples. In this work, the analytical utility of the MChip for detection and subtyping of an emerging virus was evaluated with a diverse set of A/H5N1 influenza viruses. A total of 43 different highly pathogenic A/H5N1 viral isolates that were collected from diverse geographic locations, including Vietnam, Nigeria, Indonesia, and Kazakhstan, representing human, feline, and a variety of avian infections spanning the time period 2003-2006 were used in this study. A probabilistic artificial neural network was developed for automated microarray image interpretation through pattern recognition. The microarray assay and subsequent subtype assignment by the artificial neural network resulted in correct identification of 24 "unknown" A/H5N1 positive samples with no false positives. Analysis of a data set composed of A/H5N1, A/H3N2, and A/H1N1 positive samples and negative controls resulted in a clinical sensitivity of 97% and a clinical specificity of 100%.     

Preformulation studies for an ultrashort-acting neuromuscular blocking agent GW280430A. I. Buffer and cosolvent effects on the solution stability

GW280430A is an ultrashort-acting neuromuscular blocking agent targeted at muscle relaxation to facilitate surgical intubation. The objective of this work was to study the buffer and cosolvent effects on the solution stability of GW280430A. The buffer catalytic effect was examined in citrate, malate, tartrate, and glycine by measuring the rate of degradation of GW280430A (0.2 mg/mL) at constant pH (3), ionic strength (0.15 M), and various buffer concentrations (0.01-0.05 M). The temperature dependence of the buffer catalytic effect and the degradation of the GW280430A in cosolvent (ethanol, propylene glycol, polyethylene glycol 400, N,N-dimethylacetamide)/water mixtures were studied at 40, 50, and 60°C. The loss of parent drug was monitored by reverse-phase high-performance liquid chromatography. The degradation of GW280430A followed first-order kinetics in all buffer solutions. Significant buffer-catalyzed hydrolysis of GW280430A was observed with citrate, tartrate, and malate buffers, but not in glycine-buffered solutions. The activation energies in all buffered drug solutions ranged from 70 to 80 kJ/mol and decreased with increasing buffer concentration. GW280430A degradation was primarily through ester hydrolysis and followed first-order kinetics in aqueous solutions. In cosolvent/water mixtures, new degradation products were observed, indicating a chemical reaction between GW280430A and cosolvents. The reaction activation energies in the cosolvent/water mixtures ranged from 75 to 85 kJ/mol, with the longest t_0.9 at 5°C equal to approximately 12 months and at 25°C equal to 36 days. Consideration should be given to the incorporation of glycine or a low concentration of citrate, malate, or tartrate buffer in the parenteral formulation development of GW280430A. Cosolvents prolonged the predicted t_0.9 for GW280430A in solution, but the enhancement was not significant enough to pursue a liquid formulation.     

Femur fractures in relatively low speed frontal crashes: the possible role of muscle forces.

In a sample of relatively low speed frontal collisions (mean collision speed change of 40.7 kph) the only major injury suffered by the partly or fully restrained occupant was a femur fracture. However, femur load measurements from standardized barrier crash tests for similar vehicles at a greater speed change (mean of 56.3 kph) showed that in almost all the cases, the occupant's femur would not have fractured because the loads were below fracture threshold. In order to address this discrepancy, the load in the femurs of the occupants in the crash sample were estimated and compared with the femur fracture threshold. Femur load was estimated by inspecting the scene and measuring deformations in each vehicle, defining occupant points of contact and interior surface intrusion, and calculating crash change in velocity and deceleration. From this data, the measured femoral loads from standardized crash test data in a comparable vehicle were scaled to the actual crash by considering crash deceleration, occupant weight, and restraint use. All the occupants (7 males, average age 26.7 years, 13 females, average age 36 years) sustained at least a transverse midshaft fracture of the femur with comminution, which is characteristic of axial compressive impact, causing bending and impaction of the femur. However, the estimated average maximum axial load was 8187 N (S.D. = 4343N), and the average probability for fracture was only 19% (based on the femur fracture risk criteria). In 13 crashes the fracture probability was less than 10%. Two factors were considered to explain the discrepancy. The occupant's femur was out of position (typically the driver's right front leg on the brake) and did not impact the knee bolster, instead hitting stiffer regions of the dashboard. Also, since most victims were drivers with their foot on the brake to avoid the collision, additional compressive force on the femur probably resulted from muscle contraction due to bracing for impact. Adding the estimated muscle load on the femur to the estimated external load increased the femur loads beyond threshold, explaining the fracture in all but one case. Since crash tests using dummies cannot simulate out of position occupants or muscle contraction loading, they may underestimate the total load acting on the femur during actual impacts where the driver is bracing for the crash. These results may have implications for altering knee bolster design to accommodate out of position occupants and the additional load caused by muscle forces during bracing.     

Vapor deposition method for sensitivity studies on engineered surface-enhanced Raman scattering-active substrates

The design and optimization of a vapor-phase analyte deposition method for limit of detection (LOD) studies on engineered surface-enhanced Raman scattering (SERS)-active substrates is presented. The vapor deposition method was designed to overcome current challenges in quantitative analysis of lithographically produced SERS substrates that are relatively small (hundreds of square micrometers). A custom-built flow cell was used to deposit benzenethiol from the vapor phase onto SERS-active Ag thin films, as the control substrates, and nanoaperture arrays that were generated by electron-beam lithography. The surface coverage of benzenethiol as a function of time was monitored using the ring stretching mode 1070-cm(-1) band and the trend was fit to Langmuir adsorption kinetics. The method was deemed reliable based on agreement between the LOD determined on the control substrates and previously reported values for those substrates. Application of the new method to a 20 x 20 microm(2) nanoaperture array yielded a LOD of 4.2 +/- 0.3 amol.     

Colloidal dispersion and rheology study of nanoparticles

The effects of dispersant ammonium poly(methacrylic acid) (PMAA-NH₄) and poly(acrylic acid) (PAA) on nano-Al₂O₃ particle dispersion have been investigated. Under the same dispersion viscosity, Al₂O₃ of 38 nm size requires 20 times more PAA dispersant than Al₂O₃ of 0.2 μm size but with only 9 times specific surface area increase. For the same carboxylic acid group to Al₂O₃ mole ratio, the PAA dispersant adsorbs more readily onto nano-Al₂O₃ particles than the PMAA-NH₄ dispersant and has better dispersion efficiency. Rheology measurements confirm the better dispersion and higher dispersion efficiency when PAA is used. Maximum solids loading has been predicted for each suspension based on the rheological data; this predication capability can serve as the important guidance for future dispersion designs.     

CHARACTERIZATION OF DESULFURESATION EXTRACTS FROM MIDWESTERN U.S. COALS

ABSTRACT

Coals from Midwestern States were extracted using two different processes, viz., a supercritical extraction process and a perchloroethylene coal refining process. The objectives of these processes are the selective removal of sulfur and nitrogen compounds from high-sulfur coals. The solvent extracts were analyzed using gas chromatography/mass spectrometry as well as wet chemical analysis. The extracted organosulfur compounds varied, depending upon the extraction process, extraction conditions, type of solvent, type of coal, and degree of weathering. The experimental results are compared among the types of coal as well as among the different processes, from viewpoints of chemical and molecular interaction.     

Improving GIS applicability: European challenges

Announcement

Improving GIS applicability: European challenges