The effect of pH on the functionalization of nylon fabric with carbon nanotubes.

Single walled carbon nanotubes (SWCNTs) were dispersed in water and attached to nylon fabrics by a dip-drying procedure; scanning electron microscopy and Raman spectroscopy suggest the attachment of the SWCNTs. The electrical resistance of the functionalized fabrics is found to be pH-dependent, which is correlated with the quantity of SWCNTs dispersed in water at different values of pH. This can be further ascribed to the influence of the pK(a) of the acid (e.g., acetic acid in this study) used to tune pH. The acid may affect the dispersion of SWCNTs through two different mechanisms: (1) the free protons may protonate the amine and/or sulfonate group in the dye molecules, resulting in a variety of interactions among the dye molecules, SWCNTs and water molecules and (2) the resulting ions may increase the ionic strength of the solution, compressing the electric double layers of SWCNT colloids and thus impairing their stability. The former possibility is ruled out by data obtained using X-ray photoelectron spectroscopy, Raman spectroscopy, and ultraviolet-visible-near infrared spectroscopy; thus the latter is proposed to account for the experimental results. The colour strength of the functionalized fabrics increases with increasing pH, which is in agreement with their measured electrical properties.

Tumor necrosis factor-alpha induction by reovirus serotype 3.

We have reported previously that reovirus, when used in combination with 1,3-bis(chloroethyl)-1-nitrosourea (BCNU) chemotherapy, mediates the rejection of murine ascites tumors. Surviving animals reject a challenge with the same, but not a different, tumor, which suggests that tumor-specific immunity is induced by the treatment regimen. The present study was designed to characterize the interaction between reovirus and murine peritoneal macrophages, both in vitro and in vivo, to determine whether such a relationship may play a role in immune modulation resulting in tumor rejection. The results demonstrated that reovirus can efficiently infect peritoneal macrophages in vitro and stimulate the secretion of tumor necrosis factor-alpha (TNF-alpha). In vivo administration of reovirus, however, did not produce high levels of infection in peritoneal exudate cells, even though the cells were stimulated to express detectable levels of membrane TNF-alpha. These results suggested that infection is not necessary for TNF-alpha expression and this hypothesis was supported by the observation that this expression was also stimulated in vitro by UV-inactivated reovirus. These findings suggest that one mechanism for immune stimulation by reovirus may be through the induction of TNF-alpha.

Collaborative study of the USP dissolution test for prednisone tablets with Apparatus 2.

Five lots of prednisone tablets that disintegrate within 5 min were collaboratively studied by 11 laboratories using USP Apparatus 2 under carefully controlled conditions. One lot gave complete dissolution. The reproducibility and repeatability of Apparatus 2 for the four lots still dissolving at the end of the test were 2.6 and 1.6% of label claim, respectively, for the 11 laboratories.

Systematic error associated with apparatus 2 of the USP dissolution test V: Interaction of two tableted prednisone formulations with glass and plastic vessels.

Recently marketed glass vessels that are uniform and pass USP specifications were compared with uniform plastic vessels that also pass USP specifications. Two lots of prednisone tablets, Tablet 1 and Tablet 2, were tested in both types of vessels. Tablet 1 gave higher results (+12.7% of label claim) in glass vessels at 50 rpm but gave equivalent results in either vessel at 75 rpm. Tablet 2 gave equivalent results in either vessel at 50 rpm but gave higher results (+22% of label claim) in glass vessels at 75 rpm. The type of vessel used to obtain dissolution results for tablets should be specified.

Systematic error associated with apparatus 2 of the USP dissolution test IV: effect of air dissolved in the dissolution medium.

Acceptable concentrations of gases in a medium are not well defined in USP dissolution tests. A sample of 10-mg prednisone tablets, known to be sensitive to dissolved gases, was tested with batches of purified water that contained different concentrations of air. The data suggest that the results from Apparatus 2 can be influenced by the concentration of air in the dissolution medium unless the medium remains unsaturated with air for the duration of the test. The repeatability of means of six results was markedly improved when the air concentration in the medium was accurately controlled at the beginning of the test.

Systematic error associated with apparatus 2 of the USP dissolution test III: limitations of calibrators and the USP suitability test.

The calibrator tablets now used in the USP suitability test do not reveal common sources of systematic error associated with Apparatus 2. When the apparatus was operated under conditions near or beyond USP tolerances, changes in the results of the USP calibrators were slight, whereas those of several samples of commercial prednisone tablets were significant. Thus, the USP calibrators and requirements do not guarantee suitability of the equipment for general dissolution testing of drug products.

Systematic error associated with apparatus 2 of the USP dissolution test II: Effects of deviations in vessel curvature from that of a sphere.

Dissolution vessels made from glass or plastic are recognized by the USP as being suitable for dissolution testing. Glass vessels with a bottom inside curvature flatter than that of a sphere can cause a high bias in dissolution results; vessels with a steeper curvature can cause a low bias. The inside bottom curvature of plastic vessels adhered closely to the curvature of a sphere. The plastic vessels are preferable for use if the drug is not adsorbed and the vessel is not attacked by the dissolution medium. Bias in results between individual positions of a dissolution apparatus was traced to two shafts which were not vertical.

Effects of cholesterol and 25-hydroxycholesterol on smooth muscle cell and endothelial cell growth.

Auto-oxidation products of cholesterol may play a role in atherogenesis. In order to determine whether cholesterol or 25-hydroxycholesterol, a cholesterol auto-oxidation product, affected growth of vessel wall cells, sparse and confluent cultures of rabbit thoracic aorta smooth muscle cells and human umbilical vein endothelial cells were exposed to these compounds for 88 hr. The compounds were administered at 10(-4), 10(-5), 10(-6) or 10(-7) M in either ethanol or fetal bovine serum (FBS) vehicle. Cells were counted electronically, and the results were expressed as the percent growth in experimental vs control wells. Cholesterol did not inhibit cell growth under any experimental condition. 25-Hydroxycholesterol had the following effects: inhibited confluent smooth muscle cell growth at 10(-4) M in ethanol vehicle only; inhibited sparse smooth muscle cell growth in a dose-related manner at 10(-4), 10(-5) and 10(-6) M in ethanol vehicle, but in FBS vehicle inhibited at only 10(-4) and 10(-5) M; inhibited confluent human umbilical vein endothelial cells at 10(-4) M in ethanol vehicle only; and inhibited sparse human umbilical vein endothelial cell growth at 10(-4) and 10(-5) M in ethanol vehicle only. Thus, rabbit aortic smooth muscle cell growth was more sensitive to inhibition by 25-hydroxycholesterol than human umbilical vein endothelial cell growth was.

Liquid chromatographic determination of thalidomide in tablets, capsules, and raw materials.

A simple, isocratic liquid chromatographic method for assay of thalidomide in tablets, capsules, and raw materials was developed. The method uses a Nova-Pak octadecylsilane bonded-phase column (150 x 3.9 mm, 4 microns particle size), a mobile phase of acetonitrile-water (15 + 85), a flow rate of 1 mL/min, detection at 237 nm, and phenacetin as internal standard. Phosphoric acid was used in preparation of sample solutions to inhibit thalidomide hydrolysis. Assays ranged from 99.3 to 100.4% in raw materials from 4 manufacturers, from 79.7 to 104.8% in tablets from 7 manufacturers, and from 75.3 to 102.6% in capsules from 4 manufacturers. Assay method precisions for triplicate analyses on 5 days were 0.30% for tablets, 0.22% for capsules, and 0.22% for raw materials. Recovery from simulated tablet formulations was 100%. The method has been used to analyze individual tablets and capsules for determination of content uniformity.

The fabrication of aspherical microlenses using focused ion-beam techniques.

Aspheric lenses are the most common method for correcting for spherical aberrations but, in microlens production, highly-controlled lens profiles are hard to achieve. We demonstrate a technique for creating bespoke, highly-accurate aspheric or spherical profile silicon microlens moulds, of almost any footprint, using focused ion-beam milling. Along with this, we present a method of removing induced ion-beam damage in silicon, via a hydrofluoric acid etch, helping to recover the surface's optical and chemical properties. In this paper, we demonstrate that our milled and etched moulds have a roughness of 4.0-4.1 nm, meaning they scatter less than 1% of light, down to wavelengths of 51 nm, showing that the moulds are suitable to make lenses that are able to handle light from UV up to infra-red. Using empirical experiments and computer simulations, we show that increasing the ion-dose when milling increases the amount of gallium a hydrofluoric acid etch can remove, by increasing the degree of amorphisation within the surface. For doses above 3000 µC/cm(2) this restores previous surface properties, reducing adhesion to the mould, allowing for a cleaner release and enabling higher quality lenses to be made. Our technique is used to make aspheric microlenses of down to 3 µm in size, but with a potential to make lenses smaller than 1 µm.

Investigation of slice thickness and shape milled by a focused ion beam for three-dimensional reconstruction of microstructures.

Three-dimensional reconstructions of microstructures produced by focused ion beam (FIB) milling usually assume a uniform slice thickness with flat and parallel surfaces. Measurement of the actual slice thickness and profile is difficult, and is often simply ignored. This paper reports the use of artificial 3D structures of known geometry to enable the full 3D profile of a sequence of slices produced by FIB to be measured for the first time. A transient period at the beginning of a milling process is observed in which the actual slice thickness varies by as much as ±50% from the target thickness (with significantly greater error near the base of the slice), before settling to a ±20% variation as the milling progresses. Although SEM images appear to show flat milled surfaces perpendicular to the top surface, the development of a curved, tapering milled surface is also observed. This profile is then maintained through the milling process with the bottom of the slice lagging the top by up to three slice thicknesses.

Unexplained excess of electronlike events from a 1-GeV neutrino beam.

The MiniBooNE Collaboration observes unexplained electronlike events in the reconstructed neutrino energy range from 200 to 475 MeV. With 6.46x10;{20} protons on target, 544 electronlike events are observed in this energy range, compared to an expectation of 415.2+/-43.4 events, corresponding to an excess of 128.8+/-20.4+/-38.3 events. The shape of the excess in several kinematic variables is consistent with being due to either nu_{e} and nu[over ]_{e} charged-current scattering or nu_{mu} neutral-current scattering with a photon in the final state. No significant excess of events is observed in the reconstructed neutrino energy range from 475 to 1250 MeV, where 408 events are observed compared to an expectation of 385.9+/-35.7 events.

Measurement of numicro and nue events in an off-axis horn-focused neutrino beam.

We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beam line at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle (6.3 degrees) with respect to the NuMI beam axis. Samples of charged-current quasielastic numicro and nue interactions are analyzed and found to be in agreement with expectation. This provides a direct verification of the expected pion and kaon contributions to the neutrino flux and validates the modeling of the NuMI off-axis beam.

Search for muon neutrino and antineutrino disappearance in MiniBooNE.

The MiniBooNE Collaboration reports a search for nu_{micro} and nu[over]_{micro} disappearance in the Deltam;{2} region of 0.5-40 eV;{2}. These measurements are important for constraining models with extra types of neutrinos, extra dimensions, and CPT violation. Fits to the shape of the nu_{micro} and nu[over]_{micro} energy spectra reveal no evidence for disappearance at the 90% confidence level (C.L.) in either mode. The test of nu[over]_{micro} disappearance probes a region below Deltam;{2} = 40 eV;{2} never explored before.

Measurement of the ratio of the numu charged-current single-pion production to quasielastic scattering with a 0.8 GeV neutrino beam on mineral oil.

Using high statistics samples of charged-current numu interactions, the MiniBooNE [corrected] Collaboration reports a measurement of the single-charged-pion production to quasielastic cross section ratio on mineral oil (CH2), both with and without corrections for hadron reinteractions in the target nucleus. The result is provided as a function of neutrino energy in the range 0.4 GeV

Measurement of muon neutrino quasielastic scattering on carbon.

The observation of neutrino oscillations is clear evidence for physics beyond the standard model. To make precise measurements of this phenomenon, neutrino oscillation experiments, including MiniBooNE, require an accurate description of neutrino charged current quasielastic (CCQE) cross sections to predict signal samples. Using a high-statistics sample of nu_(mu) CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events observed in a carbon-based detector. The extracted parameters include an effective axial mass, M_(A)(eff)=1.23+/-0.20 GeV, that describes the four-momentum dependence of the axial-vector form factor of the nucleon, and a Pauli-suppression parameter, kappa=1.019+/-0.011. Such a modified Fermi gas model may also be used by future accelerator-based experiments measuring neutrino oscillations on nuclear targets.

Search for electron neutrino appearance at the Delta m2 approximately 1 eV2 scale.

The MiniBooNE Collaboration reports first results of a search for nu e appearance in a nu mu beam. With two largely independent analyses, we observe no significant excess of events above the background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two-neutrino appearance-only oscillation model.

Cellular integrity is required for inhibition of initiation of cellular DNA synthesis by reovirus type 3.

Synchronized HeLa cells, primed for entry into the synthesis phase by amethopterin, were prevented from initiating DNA synthesis 9 h after infection with reovirus type 3. However, nuclei isolated from synchronized cells infected with reovirus for 9 or 16 h demonstrated a restored ability to synthesize DNA. The addition of enucleated cytoplasmic extracts from infected or uninfected cells did not affect this restored capacity for synthesis. The addition of ribonucleotide triphosphates to nuclei isolated from infected cells stimulated additional DNA synthesis, suggesting that these nuclei were competent to initiate new rounds of DNA replication. Permeabilization of infected cells did not restore the ability of these cells to synthesize DNA. Nucleoids isolated from intact or permeabilized cells, infected for 9 or 16 h displayed an increased rate of sedimentation when compared with nucleoids isolated from uninfected cells. Nucleoids isolated from the nuclei of infected cells demonstrated a rate of sedimentation similar to that of nucleoids isolated from the nuclei of uninfected cells. The inhibition of initiation of cellular DNA synthesis by reovirus type 3 appears not to have been due to a permanent alteration of the replication complex, but this inhibition could be reversed by the removal of that complex from factors unique to the structural or metabolic integrity of the infected cell.

Characteristics of reovirus-mediated chemoimmunotherapy of murine L1210 leukemia.

We have previously demonstrated the ability of reovirus to function synergistically with chemotherapy in the treatment of murine EL-4 lymphoma. This study characterizes this treatment regimen in the therapy of L1210 leukemia. Animals with an estimated tumor burden of 10(7) cells were treated with 9 mg/kg 1,3-bis(2-chloroethyl)-1-nitrosourea. Reovirus type 3, which had been quantitated either by particles or plaque-forming units (pfu), was administered 48 h after chemotherapy. Complete remission of tumor was observed in 80% of the animals which received either 10(11) particles or 10(9) pfu of reovirus. Cured animals were resistant to challenge with homologous tumor, but were susceptible to challenge with heterologous tumor. Reovirus undergoes limited replication at the tumor site, and virus-specific antibody appears only after disappearance of reovirus-infected cells and virus from the ascites fluid. Reovirus appears to function therapeutically by inducing a tumor-specific cytolytic immune response.