Ultrasonic preparation, stability and thermal conductivity of a capped copper-methanol nanofluid.

This paper describes a two-step method to prepare novel copper-methanol nanofluids capped with a short chain molecule, (3-Aminopropyl)trimethoxysilane (APTMS). Two commercial nanopowders were dispersed at various powers using a 20 kHz ultrasonic probe into solutions of methanol and the capping agent. Ultrasonic energy input was measured by calorimetry with z-average diameters, intensity and number size distributions recorded by a dynamic light scattering technique. The stability of the dispersion was monitored visually, and quantified by recording the zeta potential. Dispersions of the bare powder were used as a control. Absorption spectroscopy was used to confirm the presence of the capping agent. The thermal conductivities of 0 to 10% wt./vol. (1.1% vol.) dispersions of the capped copper-methanol nanofluid were determined using a C-Therm analyzer. Optimum ultrasonic de-agglomeration conditions gave dispersions with a z-average particle size of <200 nm and a PdI of <0.2. The capped particles showed good stability; up to six months in some instances, and an average zeta potential of +38 mV was recorded. The thermal conductivity of the nanofluid increased with concentration, and an enhancement of 9% over the base fluid was found at 10% wt./vol. (1.1% vol.). This innovative work has demonstrated the ultrasonic preparation and stability of copper nanoparticles protected with APTMS; a short chain molecule which binds to copper and prevents oxidation. The protected particles can enhance the thermal conductivity of methanol with no interference from the capping ligand.

Comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida.

The comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida was investigated. In addition, variation in scale morphology across different body regions within each species was analysed. Although considerable morphological variation was observed among scales from different body regions in both species, scales of K. albida generally have pointed anterior ends, fewer posterior points and are more heavily imbricated than those of T. georgii, which are frequently rounded anteriorly, often have many posterior points and are separated farther within the skin. In all sampled body regions and individuals, scales of T. georgii are significantly broader and have a lower length-to-width aspect ratio than those of K. albida. Superficial to the scales are denticular plates, which are ossified formations occurring on the surface layer of the epidermis; these were observed and described for T. georgii, K. albida and blue marlin Makaira nigricans. Detailed scale descriptions allow for a more accurate characterization of the variation within and differences between these two species and could potentially be a valuable tool for investigating istiophorid systematics.

Secondary contact and asymmetrical gene flow in a cosmopolitan marine fish across the Benguela upwelling zone.

The combination of oceanographic barriers and habitat heterogeneity are known to reduce connectivity and leave specific genetic signatures in the demographic history of marine species. However, barriers to gene flow in the marine environment are almost never impermeable which inevitably allows secondary contact to occur. In this study, eight sampling sites (five along the South African coastline, one each in Angola, Senegal and Portugal) were chosen to examine the population genetic structure and phylogeographic history of the cosmopolitan bluefish (Pomatomus saltatrix), distributed across a large South-east Atlantic upwelling zone. Molecular analyses were applied to mtDNA cytochrome b, intron AM2B1 and 15 microsatellite loci. We detected uncharacteristically high genetic differentiation (FST 0.15-0.20; P<0.001) between the fish sampled from South Africa and the other sites, strongly influenced by five outlier microsatellite loci located in conserved intergenic regions. In addition, differentiation among the remaining East Atlantic sites was detected, although mtDNA indicated past isolation with subsequent secondary contact between these East Atlantic populations. We further identified secondary contact, with unidirectional gene flow from South Africa to Angola. The directional contact is likely explained by a combination of the northward flowing offshore current and endogenous incompatibilities restricting integration of certain regions of the genome and limiting gene flow to the south. The results confirm that the dynamic system associated with the Benguela current upwelling zone influences species distributions and population processes in the South-east Atlantic.

New evidence for the inverse dependence of mechanical and chemical effects on the frequency of ultrasound.

Acoustic cavitation has been the subject of research and discussion for many years and it is the underlying driving force for sonochemistry. The collapse of acoustic cavitation bubbles in water near to a surface can bring about significant surface modification in terms of the mechanical damage caused by the asymmetric collapse of the bubbles which cause erosion and abrasion. A second effect of acoustic cavitation is the formation of short lived radicals caused by the breakdown of water inside the bubble. For the first time the dependence of these effects has been observed on the surface of a plastic material as a function of ultrasonic frequency.

Global population structure of the spiny dogfish Squalus acanthias, a temperate shark with an antitropical distribution.

The spiny dogfish (Squalus acanthias) is a temperate, coastal squaloid shark with an antitropical distribution in the Atlantic and Pacific oceans. The global population structure of this species is poorly understood, although individuals are known to undergo extensive migrations within coastal waters and across ocean basins. In this study, an analysis of the global population structure of the spiny dogfish was conducted using eight polymorphic nuclear microsatellite markers and a 566-bp fragment of the mitochondrial ND2 gene region. A low level of genetic divergence was found among collections from the Atlantic and South Pacific basins, whereas a high level of genetic divergence was found among Pacific Ocean collections. Two genetically distinct groups were recovered by both marker classes: one exclusive to North Pacific collections, and one including collections from the South Pacific and Atlantic locations. The strong genetic break across the equatorial Pacific coincides with major regional differences in the life-history characters of spiny dogfish, suggesting that spiny dogfish in areas on either side of the Pacific equator have been evolving independently for a considerable time. Phylogeographic analyses indicate that spiny dogfish populations had a Pacific origin, and that the North Atlantic was colonized as a result of a recent range expansion from the South American coast. Finally, the available data strongly argue for the taxonomic separation of the North Pacific spiny dogfish from S. acanthias and a re-evaluation of the specific status of S. acanthias is warranted.

Genetically monomorphic invasive populations of the rapa whelk, Rapana venosa.

Rapana venosa is a predatory marine gastropod native to the coastal waters of China, Korea, and Japan. Since the 1940s, R. venosa has been transported around the globe and introduced populations now exist in the Black Sea, the Mediterranean Sea, the Adriatic and Aegean seas, off the coasts of France and The Netherlands, in Chesapeake Bay, Virginia, USA, and in the Rio de la Plata between Uruguay and Argentina. This study surveyed variation in two mitochondrial gene regions to investigate the invasion pathways of R. venosa, identify likely sources for introduced populations, and evaluate current hypotheses of potential transportation vectors. Sequence data were obtained for the mitochondrial cytochrome c oxidase I and NADH dehydrogenase subunit 2 gene regions of 178 individuals from eight native locations and 106 individuals from 12 introduced locations. Collections from within the native range displayed very high levels of genetic variation while collections from all introduced populations showed a complete lack of genetic diversity; a single haplotype was common to all introduced individuals. This finding is consistent with the hypothesis that R. venosa was initially introduced into the Black Sea, and this Black Sea population then served as a source for the other secondary invasions by various introduction vectors including ballast water transport. Although non-native R. venosa populations currently appear to be thriving in their new environments, the lack of genetic variability raises questions regarding the evolutionary persistence of these populations.

Black walnut extract-induced laminitis in horses is associated with heterogeneous dysfunction of the laminar microvasculature.

REASONS FOR PERFORMING STUDY: Equine laminitis purportedly involves haemodynamic dysfunction at the level of the laminar vasculature. However, to date, no studies have been performed characterising the function of laminar arteries and veins during the prodromal stages of equine laminitis. HYPOTHESIS: That the prodromal stages of laminitis are associated with contractile dysfunction of the equine laminar vasculature. OBJECTIVE: To assess contractile function of laminar arteries and veins to phenylephrine (PE) and 5-hydroxytryptamine (5-HT). METHODS: Horses were administered black walnut heartwood extract (BWHE) or water (control horses) via nasogastric intubation. After euthanasia, laminar vessels (100-800 microm internal diameter) were isolated and mounted on small vessel myographs to assess contractile function. RESULTS: Contractile responses to PE or 5-HT were identical in laminar arteries isolated from either control horses or those administered BWHE. In contrast, responses to PE or 5-HT were significantly reduced in laminar veins isolated from BWHE-administered horses when compared with laminar veins isolated from control horses. CONCLUSIONS AND POTENTIAL RELEVANCE: These results are consistent with the prodromal stages of laminitis being associated with selective dysfunction of laminar veins. Further studies are required to discern the precise nature of this dysfunction and its potential relevance to the pathogenesis of acute laminitis in the horse and possible therapeutic targets for treatment.

Atrazine effects on in vitro maturation and in vitro fertilization in the bovine oocyte.

The effect of low levels of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) on in vitro oocyte maturation, in vitro capacitation of sperm, or in vitro fertilization of bovine oocytes and on the quality of blastocyst formation was studied. Bovine oocytes collected from abattoir ovaries were matured, fertilized, and developed to the blastocyst stage in vitro. Embryos that reached a morula or blastocyst stage were stained with Hoechst 33258 stain to determine the number of blastomeres per embryo. Three bulls whose fertilization rates were proven consistent among straws were used for this study. Atrazine was tested at concentrations of 0.01, 0.1, 1, and 10 microM in either the maturation medium, sperm capacitation medium, or the fertilization medium. Because atrazine was dissolved in ethanol, an ethanol control was used to determine any possible effects of ethanol on the in vitro process. The addition of atrazine to both the maturation and fertilization media did not result in any significant difference in fertilization rates between the controls and the treatments. In the capacitation medium, a significant difference between the controls and the atrazine levels of 0.1, 1, and 10 microM was noted for one bull. Atrazine did not affect the number of blastomeres per embryo. There was not a significant difference (p>0.05) in the number of blastomeres per embryo between the controls and the different levels of atrazine in each medium. This study indicates that low levels of atrazine do not have an effect on in vitro fertilization rates or the number of blastomeres per embryo produced in vitro.

Reconciling patterns of inter-ocean molecular variance from four classes of molecular markers in blue marlin (Makaira nigricans).

Different classes of molecular markers occasionally yield discordant views of population structure within a species. Here, we examine the distribution of molecular variance from 14 polymorphic loci comprising four classes of molecular markers within approximately 400 blue marlin individuals (Makaira nigricans). Samples were collected from the Atlantic and Pacific Oceans over 5 years. Data from five hypervariable tetranucleotide microsatellite loci and restriction fragment length polymorphism (RFLP) analysis of whole molecule mitochondrial DNA (mtDNA) were reported and compared with previous analyses of allozyme and single-copy nuclear DNA (scnDNA) loci. Temporal variance in allele frequencies was nonsignificant in nearly all cases. Mitochondrial and microsatellite loci revealed striking phylogeographic partitioning among Atlantic and Pacific Ocean samples. A large cluster of alleles was present almost exclusively in Atlantic individuals at one microsatellite locus and for mtDNA, suggesting that, if gene flow occurs, it is likely to be unidirectional from Pacific to Atlantic oceans. Mitochondrial DNA inter-ocean divergence (FST) was almost four times greater than microsatellite or combined nuclear divergences including allozyme and scnDNA markers. Estimates of Neu varied by five orders of magnitude among marker classes. Using mathematical and computer simulation approaches, we show that substantially different distributions of FST are expected from marker classes that differ in mode of inheritance and rate of mutation, without influence of natural selection or sex-biased dispersal. Furthermore, divergent FST values can be reconciled by quantifying the balance between genetic drift, mutation and migration. These results illustrate the usefulness of a mitochondrial analysis of population history, and relative precision of nuclear estimates of gene flow based on a mean of several loci.

Tonic regulation of vascular tone by nitric oxide and chloride ions in rat isolated small coronary arteries.

We have investigated the involvement of Cl(-) in regulating vascular tone in rat isolated coronary arteries mounted on a small vessel myograph. Mechanical removal of the endothelium or inhibition of nitric oxide (NO) synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME, 10(-4) M) led to contraction of rat coronary arteries, and these contractions were sensitive to nicardipine (10(-6) M). This suggests that release of NO tonically inhibits a contractile mechanism that involves voltage-dependent Ca(2+) channels. In arteries contracted with L-NAME, switching the bathing solution to physiological saline solution with a reduced Cl(-) concentration potentiated the contraction. DIDS (5 x 10(-6)-3 x 10(-4) M) caused relaxation of L-NAME-induced tension (IC(50) = 55 +/- 10 microM), providing evidence for a role of Cl(-). SITS (10(-5)-5 x 10(-4) M) did not affect L-NAME-induced tension, suggesting that DIDS is not acting by inhibition of anion exchange. Mechanical removal of the endothelium led to contraction of arteries, which was sensitive to DIDS (IC(50) = 50 +/- 8 microM) and was not affected by SITS. This study suggests that, in rat coronary arteries, NO tonically suppresses a contractile mechanism that involves a Cl(-) conductance.

Actin gene family evolution and the phylogeny of coleoid cephalopods (Mollusca: Cephalopoda).

Phylogenetic analysis conducted on a 784-bp fragment of 82 actin gene sequences of 44 coleoid cephalopod taxa, along with results obtained from genomic Southern blot analysis, confirmed the presence of at least three distinct actin loci in coleoids. Actin isoforms were characteri zed through phylogenetic analysis of representative cephalopod sequences from each of the three isoforms, along with translated actin cDNA sequences from a diverse array of metazoan taxa downloaded from GenBank. One of the three isoforms found in cephalopods was closely related to actin sequences expressed in the muscular tissues of other molluscs. A second isoform was most similar to cytoplasmic-specific actin amino acid sequences. The muscle type actins of molluscs were found to be distinct from those of arthropods, suggesting at least two independent derivations of muscle actins in the protostome lineage, although statistical support for this conclusion was lacking. Parsimony and maximum-likelihood analyses of two of the isoforms from which >30 orthologous coleoid sequences had been obtained (one of the cytoplasmic actins and the muscle actin) supported the monophyly of several higher-level coleoid taxa. These included the superorders Octopodiformes and Decapodiformes, the order Octopoda, the octopod suborder Incirrata, and the teuthoid suborder Myopsida. The monophyly of several taxonomic groups within the Decapodiformes was not supported, including the orders Teuthoidea and Sepioidea and the teuthoid suborder Oegopsida. Parametric bootstrap analysis conducted on the simulated cytoplasmic actin data set provided statistical support to reject the monophyly of the Sepioidea. Although parametric bootstrap analysis of the muscle actin isoform did not reject sepioid monophyly at the 5% level, the results (rejection at P: = 0.068) were certainly suggestive of sepioid nonmonophyly.

Electromyographic activity of the lumbar extensor muscles: effect of angle and hand position during Roman chair exercise.

OBJECTIVE: To evaluate the effects of angle and hand position during variable-angle Roman chair (VARC) back extension exercise on lumbar paraspinal electromyographic (EMG) activity. DESIGN: Descriptive, repeated measures. SETTING: University-based musculoskeletal research laboratory. PARTICIPANTS: Two female and eight male volunteers recruited from a university setting. INTERVENTION AND OUTCOME MEASURES: Surface integrated EMG activity was recorded from the L3-L4 paraspinal region during 24 10-second repetitions of dynamic back extension exercise, each consisting of a unique VARC angle (six total) and subject hand position (four total). Lumbar paraspinal surface integrated EMG activity measured in millivolts per repetition was used for analysis. RESULTS: Significant lumbar paraspinal EMG activity was evident during each of the 24 repetitions (p < or = .05), with a 104% increase in activity noted between the lowest and highest. EMG activity increased progressively among hand positions and as the VARC angle became more horizontal. VARC angle affected EMG activity more than hand position, but the greatest impact on EMG activity was produced by modifying both angle and hand position. CONCLUSION: Lumbar paraspinal EMG activity can be altered during VARC back extension exercise by changing angle and hand position. Clinicians can use these data to develop progressive resistance exercise programs using the VARC apparatus.

Pelvic restraint effect on lumbar gluteal and hamstring muscle electromyographic activation.

OBJECTIVE: To evaluate the influence of pelvic restraint on electromyographic activation (neural drive) of the lumbar extensor, gluteal, and hamstring muscles during submaximal dynamic lumbar extension in an upright seated position. DESIGN: Randomized, balanced, crossover trial comparing the electromyographic activation of the lumbar, gluteal, and hamstring muscles during dynamic lumbar extension exercise with and without pelvic restraint. SETTING: Research laboratory at a private research university. SUBJECTS: Twelve apparently healthy men (ages 18 to 50 yrs). INTERVENTION: Dynamic lumbar extension exercises. MAIN OUTCOME MEASURE: Electromyographic recordings. RESULTS: Pelvic restraint did not influence the relative activation of the lumbar, gluteal, or hamstring muscle groups (p< or =.05) during submaximal dynamic lumbar extension exercise. The relative activation of the gluteal muscles was significantly lower than that of the lumbar extensor and hamstring muscle groups. CONCLUSIONS: Pelvic restraint is not a requirement to promote neural drive to the lumbar musculature during submaximal dynamic lumbar extension exercise performed in an upright seated position. Submaximal lumbar extension exercise reduces the relative contribution of the gluteal muscles compared with a maximal voluntary isometric contraction.

Endoscopic cauterization for treatment of fourth branchial cleft sinuses.

Fourth branchial cleft sinuses are rare, and the nature of their origin is controversial. Clinical presentation is varied because they may present as asymptomatic neck masses, recurrent neck abscesses, or suppurative thyroiditis. We describe herein 7 children who presented with abscesses on the left side of their necks, 3 of whom had abscesses that involved the thyroid gland. Direct laryngoscopy revealed that all 7 children had a sinus tract opening into the apex of the piriform sinus. Endoscopic obliteration of this tract was achieved using an insulated electrocautery probe either when the abscess was initially incised and drained or 4 to 6 weeks later. All 7 children recovered uneventfully. Four of the 7 children were followed up for more than 18 months without recurrence.

Quantification of full-range-of-motion unilateral and bilateral knee flexion and extension torque ratios.

OBJECTIVES: To evaluate the reliability and variability of repeated measurements of isometric knee flexion and extension strength, to quantify the extent of measurement error that may occur due to gravity, and to quantify isometric knee flexion/extension torque ratios at multiple angles through a full range of motion. DESIGN: Reliability assessment. SETTING: A university exercise center. PARTICIPANTS: Seventy-seven healthy men and women recruited from a university and surrounding community. INTERVENTION: Isometric knee flexion and extension strength tests. MAIN OUTCOME MEASURES: Knee flexion/extension strength was measured at 6 degrees, 24 degrees, 42 degrees, 60 degrees, 78 degrees, 96 degrees, and 108 of knee flexion. Before each contraction, subjects were instructed to completely relax the limbs to measure the mass of the lower leg. Torque values obtained during relaxation at each angle were added to or subtracted from "Total Torque" (TTQ) at peak exertion. The adjusted value was recorded as "Net Muscular Torque" (NMT). RESULTS: Reliability for the unilateral and bilateral tests was high (r =.88 to r=.98) and measurement variability low (SEM%=5.1% to 12.6%). There was a statistically significant difference at each angle of measurement between the TTQ and NMT values for both knee flexion and extension. Knee flexion/extension ratios were highly dependent on the angle tested, ranging from 1.30 (at 60) to .31 (at 1080). CONCLUSIONS: Isometric testing, using standardized angles, can reliably quantify knee flexion/extension strength. Furthermore, these findings emphasize the importance of correcting for the mass of the lower leg when assessing muscle function. Angle-specific knee flexion/extension torque ratios should provide clinicians with a more precise method of evaluating muscular balance (imbalance) throughout the range of motion.

Peroxynitrite-mediated vasorelaxation: evidence against the formation of circulating S-nitrosothiols.

Peroxynitrite-induced relaxation of isolated vessels may involve the formation of S-nitrosothiols. This study characterized the hemodynamic effects of systemically injected peroxynitrite in penotobarbital sodium-anesthetized rats and determined whether these effects were due to the formation of S-nitrosothiols. We utilized L-penicillamine, which attenuates the hemodynamic effects of systemically injected S-nitrosothiols. The hemodynamic effects of peroxynitrite and the S-nitrosothiols L-S-nitrosocysteine, L-S-nitrosoglutathione, and S-nitrosoalbumin were determined before and 25 min after the administration of L-penicillamine or saline. Peroxynitrite and the S-nitrosothiols produced dose-dependent reductions in mean arterial pressure and mesenteric and hindquarter vascular resistances. The hypotensive and vasodilator effects of the S-nitrosothiols were significantly reduced by L-penicillamine. In contrast, the hemodynamic actions of peroxynitrite were unaffected by L-penicillamine. Therefore, peroxynitrite produces hypotensive and vasodilator responses in anesthetized rats that are unlikely to be due to the formation of circulating S-nitrosothiols. The mechanisms by which peroxynitrite produces vasodilatation in vivo remain to be determined.

Effects of age, physical training, and physical fitness on coronary heart disease risk factors in older track athletes at twenty-year follow-up.

OBJECTIVE: To compare current coronary heart disease (CHD) risk factor values in older athletes with mid-life measures and to examine the associations between changes in CHD risk factors with aging, physical training, and physical fitness. DESIGN: Prospective study with three longitudinal evaluation points: initial (T1), 10-year (T2), and 20-year (T3). Subjects were selected because of their elite status in Masters track competition. SETTING: University and medical center laboratories. PARTICIPANTS: Participants were 60 to 92 years of age and included 21 of the initial 27 subjects. At T3, subjects were divided into three groups, based on physical activity levels: high intensity (H), remained elite in national and international competition (n = 9); moderate intensity (M) continued frequent rigorous endurance training but rarely competed (n = 10); and low intensity (L) greatly reduced their training volume and intensity (n = 2). MEASUREMENTS: Smoking history; family history of coronary or cerebrovascular disease; resting blood pressure; resting electrocardiogram (ECG); serum total cholesterol, plasma glucose; body weight, % body fat, body mass index, waist:hip ratio; training pace and mileage; maximal oxygen consumption VO2 max). MAIN RESULTS: Several risk factors (smoking, diabetes, obesity) were never present, and the prevalence of other risk factors (family history of cardiovascular disease, abnormal resting ECG) remained low through T3 (< or = 14% of subjects). Mean systolic and diastolic blood pressure remained low without medication, but diastolic blood pressure measurements had the greatest redistribution between evaluation periods of any risk factor (r = .16, P = .479, T1 to T2). Mean total cholesterol was lower at T2 (-13%, P = .005) and T3 (-14%, P = .019) compared with T1. Change in VO2 max was correlated with changes in body weight (r = -.44, P = .048) and % fat (r = -.52, P = .015) from T1 to T2, whereas age was correlated to changes in systolic blood pressure (r = -.61, P = .003) and total cholesterol (r = -.49, P = .023) from T2 to T3. CONCLUSIONS: The prevalence of CHD risk factors remained low, and mean risk factor values remained low and generally stable in older athletes who had maintained habitual exercise training.

'Total evidence' refutes the inclusion of Perkinsus species in the phylum Apicomplexa.

The phylogenetic affinities of the oyster pathogen Perkinsus marinus were investigated with morphology, 18S-like rDNA data and actin sequence data. Morphological investigations revealed that Perkinsus species do not have a conoid and that other criteria which have been used to place them in the Apicomplexa are general to alveolates. When considered separately, 18S-like rDNA and actin data sets each support a closer affinity for Perkinsus marinus with the dinoflagellates. However, each of these separate analyses possess their own biases and weaknesses. Use of the phylogenetic principle of 'total evidence' in which data sets are combined in simultaneous analysis yielded a more robust hypothesis that is stable both to character and taxonomic sampling. The resulting cladogram strongly corroborates the placement of Perkinsus species with the Dinoflagellida and not with the Apicomplexa.

Phylogenetic analysis of Perkinsus based on actin gene sequences.

Perkinsus species presently are classified within the phylum Apicomplexa. This placement, however, is controversial. Based upon morphological observations and phylogenetic analyses of the small subunit ribosomal RNA gene, it has been suggested that Perkinsus may be more closely related to dinoflagellates. To reevaluate the phylogenetic position of Perkinsus, we obtained nucleotide sequence data for actin genes from Perkinsus marinus and 2 dinoflagellates, Prorocentrum minimum and Amphidinium carterae. Results indicated that there are 2 closely related actin genes in the genome of P. marinus. Phylogenetic comparisons of these actin gene fragments of P. marinus to available actin gene sequences for several ciliates and apicomplexans and to the 2 actin gene sequences from dinoflagellates obtained in this study supported a closer affinity of P. marinus to dinoflagellates than to apicomplexans.