Tailored SWCNT functionalization optimized for compatibility with epoxy matrices.

We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by in situ diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture.

Characterization of two New York City Jewish populations at six short tandem repeat loci.

The Hasidic and non-Hasidic Jewish communities of New York City represent two subpopulations with long-documented histories of restrictive marriage patterns and a high degree of endogamy. As part of a continuing study into their genetic structure, allele frequencies were determined for the six tetrameric short tandem repeat (STR) loci: FESFPS, F13AO1, vWA, CSF1PO, TPOX, and THO1. All loci were tested for Hardy-Weinberg equilibrium (HWE) by three tests: chi-square analysis, Monte Carlo chi-square analysis. and the exact test. The non-Hasidic population failed to meet HWE at the F13A01, FESFPS, and CSF1PO loci by all three tests. The Hasidic population also failed to meet HWE at the same loci by some of the tests. Comparison of the Hasidic to the non-Hasidic population using an R x C contingency table demonstrated a similarity at only the vWA locus. Significant differences exist when comparing the two Jewish populations to a reference Caucasian population.

Imaging in the preoperative assessment of conjoined twins.

Conjoined twins are rare and present a unique challenge to pediatric surgeons and radiologists. Planning of surgical separation is aided by accurate preoperative imaging. Such twins are classified according to the most prominent site of connection: the thorax (thoracopagus), abdomen (omphalopagus), sacrum (pygopagus), pelvis (ischiopagus), skull (craniopagus), face (cephalopagus), or back (rachipagus). The area of fusion largely determines the imaging modalities used. Thoracic conjunction is most common and requires cardiac assessment. Magnetic resonance imaging and computed tomography provide excellent anatomic and bone detail, demonstrating organ position, shared viscera, and limited vascular anatomy. Contrast material radiography allows evaluation of the gastrointestinal and urogenital tracts, and a shared liver requires assessment of anatomy, vascularization, and biliary drainage. Angiography helps define specific vascular supply, which is useful in determining the distribution of shared structures between the twins at surgery. Each set of conjoined twins is unique. An imaging strategy to accurately define anatomic fusion, vascular anomalies, and other associated abnormalities is important for surgical planning and prognostic information.

Anomalous Vibrational Dependence of the Rotational and Hyperfine Parameters in the B(4)Pi-X(4)Sigma(-) Transition of NbO.

The laser excitation spectrum of jet-cooled NbO in the region 16 000-18 000 cm(-1) has been recorded at high resolution, giving rotational and hyperfine constants for the levels v=0-3 of the B(4)Pi state and v=1 of the X(4)Sigma(-) state; zero gaps have also been measured at low resolution for some weaker bands involving higher vibrational levels. Taken together with the laser data for the B-X (0,0) band from Adam et al. (J. Chem. Phys. 94, 6240-6262 (1994)) and the Fourier transform emission data for the doublet manifold from Launila et al. (J. Mol. Spectrosc. 186, 131-143 (1997)), the new data give a very complete picture of the vibrational energy level pattern in this region. Strong irregularities in the vibrational dependences of the B(4)Pi rotational and hyperfine constants can be interpreted in terms of spin-orbit interaction between the B(4)Pi state and the f(2)Pi, e(2)Phi, and d(2)Delta states. The interaction is strong enough that all three doublet states can be seen in absorption from the X(4)Sigma(-) ground state, adding to the complexity of the spectrum. The hitherto unknown sigmadeltasigma* (4)Delta state is estimated to lie near 17 500 cm(-1), from the change of sign in the spin-rotation parameter gamma of the B(4)Pi state between v=2 and 3. Copyright 2001 Academic Press.

D1S80 allele frequencies in Hasidic and non-Hasidic New York City Jewish populations.

Allele frequencies were determined for the VNTR locus D1S80 in Hasidic and non-Hasidic Ashkenazi New York City Jewish subpopulations. Samples were amplified via the polymerase chain reaction and underwent genotyping using polyacrylamide gel electrophoresis. In the Hasidic population 14 alleles were observed as opposed to 19 alleles in the non-Hasidic community. Both populations were tested for Hardy-Weinberg equilibrium. The frequency data obtained can be used for comparison to other populations and for allele and genotype frequency estimates in genetic marker profiling of evidentiary specimens.

HLA-DQA1 and polymarker allele frequencies in two New York City Jewish populations.

Allele and genotype frequencies were determined for the HLA-DQA1 and Amplitype Polymarker loci (low density lipoprotein receptor (LDLR), glycophorin A (GYPA), hemoglobin G gammaglobin (HBGG), D7S8, and group-specific component (Gc)) in Hasidic and non-Hasidic Ashkenazi New York City Jewish subpopulations. For all loci tested, except HBGG, the 2 subpopulations meet the assumption of Hardy-Weinberg equilibrium. Comparison of various allele and genotype frequencies for the Hasidic and the non-Hasidic groups showed no significant differences. Comparison of the various allele frequencies in the two subpopulations to another Caucasian group revealed significant differences at the HLA-DQA1 and D7S8 loci in the Hasidic group. These frequency data can be used for comparison to other populations and for frequency estimates in DNA profiling.

The effect of local anaesthetics on the thermal sensitivity of HTC cells.

Local anaesthetics caused death of HTC cells, and the order of toxicity (dibucaine > tetracaine > procaine) correlated with their oil:water partition coefficients. Cytotoxic effects of hyperthermia were enhanced by subtoxic levels of anaesthetics and again, their potency was related to the oil:water partition coefficients. DPH fluidity in plasma membranes at 37 degrees C was increased by dibucaine and tetracaine but not by procaine up to 5mM. At 43 degrees C, plasma membrane fluidity was increased by dibucaine but not by tetracaine or procaine. The results suggest that fluidisation of the hydrophobic core of the membrane may contribute to anaesthetic potentiation of heat cell death.

Effect of dietary modulation of membrane lipid composition on the thermostability of HTC cells and of a membrane enzyme.

Growth of hepatoma tissue culture (HTC) cells in the presence of linoleic (18:2) or arachidonic (20:4) acids for 36 h caused an increased cell thermosensitivity. Plasma membrane-rich fractions were purified (15-20-fold) with high yield (30%) from control and fatty acid-supplemented cells. Contamination with membranes from mitochondria, lysosomes and endoplasmic reticulum was low. Supplementation significantly increased the level of the supplemented fatty acid and decreased the level of oleic acid (18:1) in plasma membrane phospholipids (PL), causing a significant decrease in the oleic acid:PUFA (polyunsaturated fatty acid) ratio. No significant changes occurred in other parameters such as cholesterol:PL, cholesterol:protein or PL:protein ratios. Plasma membranes from PUFA-supplemented cells exhibited a lower membrane order, compared with control cell membranes, as determined by DPH fluorescence polarization over the temperature range 4-40 degrees C. Isothermal inactivation of alkaline phosphodiesterase I in plasma membranes from control and supplemented cells showed curvilinear kinetics. The change in membrane composition and order following supplementation with arachidonic acid was associated with increased thermosensitivity of this enzyme. These data are discussed with respect to the suggestion that the plasma membrane may be a target for cellular thermal injury and death.

A 4-year controlled clinical study into the use of a ceramic hydroxylapatite implant material for the treatment of periodontal bone defects.

10 patients with chronic adult periodontitis who had greater than 1 tooth with infra-bony pockets were treated at the test defects by periodontal flap procedures with implantation of hydroxylapatite particles; the control defects were treated by the same surgical procedures but without the implant. A total of 58 test defects and 59 control defects were treated. Each defect had measurements carried out at given sites on the involved tooth surfaces, the sites being considered for subsequent tabulation purposes under the category of shallow (less than 3 mm) moderate (3-6 mm) and deep (greater than 6 mm) initial pocket depths. There were 146 and 152 shallow sites, 216 and 241 moderate sites and 140 and 133 deep sites, at test and control sites, respectively. Measurements of recession, probing pocket depths and probing attachment levels were made at 6 months and 1, 2, 3 and 4 years. At all sites over the period of the study, for the moderate and deep initial pockets there was a significant reduction in probing depths and an increase in the probing attachment levels. At the 4th year of assessment for the initially deep pockets, the reduction in probing depths was significantly greater for the sites treated with the implant material. In view of the difficult clinical problem posed by the treatment of teeth with deeper periodontal bone defects, further research using either this type of implant material or similar material should be considered.

Neural networks in forensic science.

Neural networks were developed to study and mimic the functioning of the human brain. Humans are good at pattern recognition; the question is how good neural networks are at it, particularly with problems of forensic science interest. Simulation experiments with a type of neural network known as a Hopfield net indicate that it may have value for the storage of toolmark patterns (including bullet striation patterns) and for the subsequent retrieval of the matching pattern using another mark by the same tool for input. Another type of neural network, the back-propagation network (BPN), is useful for applications similar to those for which standard statistical methods of pattern classification can be used. This would be an appropriate approach to the matching of general component patterns, such as gas chromatograms of gasoline, or pyrolysis patterns from materials of forensic science interest, such as paint. The BPN may provide better results than statistical methods, but it is currently necessary to try both to determine which would be best for any given situation.

Carcinoid tumour of the thymus with Cushing's syndrome.

A 29-yr-old male developed Cushing's syndrome with severe hypokalaemia, alkalosis and hypernatraemia. He died with Pseudomonas septicaemia and Nocardia pneumonia. At autopsy he was found to have a carcinoid tumour of the thymus which was not suspected before death, and marked bilateral hyperplasia of the adrenal cortex.

Extramedullary Plasmacytoma of the Gastro-intestinal Tract.

A case of plasmacytoma affecting the terminal small bowel is described. This is a rare condition, and its importance lies in its relationship to other myelomatous pathological conditions. In the case reported it would appear that the tumour arose primarily in the small bowel and that the bone marrow remained normal.