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At least 451 records · Page 25Linked to original sources
PubMed1994

Non-explosive blast injury of the ear.

Non-explosive blast injury of the ear refers to the otological trauma caused by a blow to the ear that seals the external auditory meatus. It results in a sudden increase of air pressure within the ear canal that strikes the tympanic membrane. The present study portrays the various aspects of middle and inner ear damage in 91 patients resulting from an assault we entitled a 'non-explosive blast injury' to the ear. Sixty cases were caused by a slap or a fist, 13 patients suffered sport accidents, mostly in ball games, and 18 patients were injured during swimming and water sports activities. The common symptoms were hearing loss, earache, tinnitus, vertigo and otorrhoea. All 91 patients presented with acute perforations of their eardrums. The mean conductive hearing loss was 11.2 dB. A high tone sensorineural hearing loss was detected in only 20 per cent of the patients. A spontaneous closure of the perforation with a conservative management approach was observed in 94.8 per cent of the patients. Healing of the perforation was always associated with closure of the air-bone gap, while the results of the sensorineural hearing loss recovery were less favourable.

Adolescent↗
PubMed2001

Performance evaluation of an in-injection port thermal desorption/gas chromatographic/negative ion chemical ionization mass spectrometric method for trace explosive vapor analysis.

A gas chromatographic method utilizing thermal desorption of Tenax TA and sol-gel sorbent traps has been developed and validated for the analysis of trace explosive vapor with negative ion chemical ionization mass spectrometric detection. Sorbent tubes were packed with Tenax TA and sorbent particles prepared in-house by the sol-gel process. Thermal desorption was performed within a split/splitless injection port with minimal instrument modification. Performance was characterized by relative thermal desorption recovery, precision (reproducibility), linearity of the calibration, and method detection limits. Method validation was performed with a series of dinitrotoluenes, dinitrobenzene, trinitrotoluene, trinitrobenzene, two aminodinitrotoluenes, three nitroesters, and two nitramines. The performance of Tenax TA and the sol-gel sorbents is evaluated based on the method validation data. The method was applied to the analysis of trace explosive vapor collected and concentrated with sol-gel solid sorbent traps from the headspace of a smokeless gunpowder sample.

Journal Article↗
PubMed2006

Determination of peroxide-based explosives using liquid chromatography with on-line infrared detection.

A nondestructive analytical method for peroxide-based explosives determination in solid samples is described. Reversed-phase high-performance liquid chromatography in combination with on-line Fourier transform infrared (FT-IR) detection is used for the analysis of triacetonetriperoxide (TATP) and hexamethylenetriperoxide diamine (HMTD). In contrast to other liquid chromatographic methods with optical detection, no derivatization or decomposition of the peroxides is required. The peroxides are identified and quantified via their characteristic absorption spectra in the mid-infrared range of the electromagnetic spectrum. The detection limit of 0.5 mmol L-1 for HMTD and 1 mmol L-1 for TATP allows the identification of the explosives in complex matrixes.

Journal Article↗
PubMed2000

Separation and detection of explosives on a microchip using micellar electrokinetic chromatography and indirect laser-induced fluorescence

A new approach for sensitive detection on a microfabricated chip is presented. Indirect laser-induced-fluorescence (IDLIF) was used to detect explosive compounds after separation by micellar electrokinetic chromatography (MEKC). The detection setup was used in an epifluorescence configuration with excitation provided by a near-IR diode laser operating at 750 nm. To achieve indirect detection, a low concentration of a dye (5 microM Cy7) was added to the running buffer as a visualizing agent. Using this methodology, a sample containing 14 explosives (EPA 8330 mixture) was examined. Concentrations of 1 ppm of trinitrobenzene (TNB), trinitrotoluene (TNT), dinitrobenzene (DNB), tetryl, and 2,4-dinitrotoluene (2,4-DNT) could be detected with S/N ratios between 3 and 10. Analyses showing 10 peaks, with plate numbers on the order of 60000, were completed within 60 s using a 65 mm long separation channel. The three isomers of nitrotoluene (2-, 3-, and 4-nitrotoluene) were not resolved. Additionally, the two nitramines (HMX and RDX) could only be detected at much higher concentrations, likely due to the low fluorescence quenching efficiencies of these compounds. The analysis method was also used to separate and detect nitroaromatic compounds in extracts from spiked soil samples. The presence of 1 ppm (1 microg of analyte/1 g of soil) of TNB, DNB, TNT, tetryl, 2,4-DNT, 2,6-DNT, 2-NH2-4,6-DNT, and 4-NH2-2,6-DNT could readily be detected. In the interest of increasing the sensitivity of the analysis, various on-chip injection schemes were evaluated. It was found that a 250 microm double-T injector gave a 35% increase in peak signal compared to a straight-cross injector, which is less than expected based on injected volume.

Journal Article↗
PubMed1999

Synthesis, Characterization, and Explosive Properties of the Nitrogen-Rich Borazine [H(3)N(3)B(3)(N(3))(3)].

The azidoborazines [Me(3)N(3)B(2)(Me)(2)B(N(3))] and [H(3)N(3)B(3)(N(3))(3)] were prepared from the combination of Me(3)SiN(3) and the chloroborazines [Me(3)N(3)B(2)(Me)(2)BCl] and (H(3)N(3)B(3)Cl(3)). The compounds have been characterized by analytical and spectroscopic methods. The molecular structure of [H(3)N(3)B(3)(N(3))(3)] has been confirmed by single-crystal X-ray diffraction techniques: triclinic space group P&onemacr; with a = 8.579(1) Å, b = 9.182(1) Å, c = 12.043(1) Å, alpha = 104.62(1) degrees, beta = 90.26(1) degrees, gamma = 110.74(1) degrees, and Z = 4. The thermal behavior of the azides have been examined by TGA/DTA. The explosion sensitivity of [H(3)N(3)B(3)(N(3))(3)], which contains 82.58% nitrogen by weight, has been accessed by drop weight impact, spark, and friction tests. These measurements indicate that [H(3)N(3)B(3)(N(3))(3)] is a relatively sensitive explosive. The Staudinger reactivity of the azides with Ph(3)P was examined, and [H(3)N(3)B(3)(N(3))(3)] was found to produce [Ph(3)P=NH(2)](N(3)). The molecular structure of this compound was determined by single-crystal X-ray diffraction techniques: orthorhombic space group P2(1)2(1)2(1) with a = 10.649(2) Å, b = 11.737(3) Å, c = 13.364(4) Å, alpha = beta = gamma = 90 degrees, Z = 4.

Journal Article↗
PubMed2005

Decomposition of triacetone triperoxide is an entropic explosion.

Both X-ray crystallography and electronic structure calculations using the cc-pVDZ basis set at the DFT B3LYP level were employed to study the explosive properties of triacetone triperoxide (TATP) and diacetone diperoxide (DADP). The thermal decomposition pathway of TATP was investigated by a series of calculations that identified transition states, intermediates, and the final products. Counterintuitively, these calculations predict that the explosion of TATP is not a thermochemically highly favored event. It rather involves entropy burst, which is the result of formation of one ozone and three acetone molecules from every molecule of TATP in the solid state.

Journal Article↗
PubMed2005

Canard explosion and coherent biresonance in the rate oscillation of CO oxidation on platinum surface.

The relationship between canard explosion and coherent biresonance is analyzed by numerically investigating a temporal dynamical model of CO oxidation on Pt surface. Canard explosion, manifesting itself by a dramatic change in the amplitude and period of a periodic orbit within a very narrow interval of a control parameter, is the result of multiple time scales in a dynamical system and is common in excitable systems. Coherent biresonance, namely, two peaks on the signal-to-noise ratio (SNR) curve when varying noise intensity, is a novel phenomenon of coherent resonance which is well-known in excitable systems. When the control parameter is varied from a stable fixed point, crossing the supercritical Hopf bifurcation, one of the peaks that corresponds to relatively larger noise intensity, keeps a constant height and position, while the other becomes higher and moves to lower noise level. When we consider the case in which two control parameters are perturbed by independent noise simultaneously, an interesting picture of one valley between two ridges appears on the 3D surface of SNR.

Carbon Monoxide↗
PubMed1997

Risperidone and explosive aggressive autism.

Many autistic patients with mental retardation have difficulties with explosivity and aggression. They often prove resistant to various pharmacotherapeutic interventions. In this study, 11 male outpatients (mean 18.3 years) were administered risperidone in an open-label fashion. The risperidone was started at 0.5 mg daily, and titrated upwards until maximum clinical benefit occurred. Serial clinical interviews were conducted, and Conners Parent-Teacher Questionnaires (short form) were completed by the caretakers. Substantial clinical improvement was noted almost immediately in each patient, with aggression, self-injury, explosivity, and poor sleep hygiene most improved. The modal dose for optimal response was 0.5 mg bid. Weight gain was a significant side effect (average velocity of 0.47 kg per week), while none of the patients experienced extrapyramidal side effects.

Activities of Daily Living↗
PubMed1970

Explosive nucleosynthesis in stars.

Recent calculations provide convincing evidence that the naturally occurring nuclei were produced in explosions. The required temperature, density and expansion rate strongly suggest that before the explosion the objects were ordinary evolved massive stars. We review these new developments and present a new table indicating our hypothesis concerning the origin of the nuclei in the mass range 20 < or = A < or = 62.

Journal Article↗
PubMed2006

A novel explosive process is required for the gamma-ray burst GRB 060614.

Over the past decade, our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly, thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (> 2 s) GRBs are associated with the explosive deaths of massive stars ('collapsars', ref. 1), which produce accompanying supernovae; the short-duration (< or = 2 s) GRBs have a different origin, which has been argued to be the merger of two compact objects. Here we report optical observations of GRB 060614 (duration approximately 100 s, ref. 10) that rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive collapsar that powers a GRB without any associated supernova, or a new type of 'engine', as long-lived as the collapsar but without a massive star. We also show that the properties of the host galaxy (redshift z = 0.125) distinguish it from other long-duration GRB hosts and suggest that an entirely new type of GRB progenitor may be required.

Journal Article↗
PubMed2006

Colonic explosion during endoscopic polypectomy: avoidable complication or bad luck?

We were confronted recently by an intraluminal colonic explosion during a colonic polypectomy procedure using snare loop electrocautery, probably caused by the presence of hydrogen and/or methane in combustible concentrations. Our patient needed immediate surgery, when several lacerations were found in the colon: a right hemicolectomy and a partial sigmoid resection with primary anastomoses were performed. Colonic bacteria, rests of fecal fluids, certain cleansing solutions, and oxygen insufflation are the main factors involved in cases of colonic explosion. We describe this dramatic event in our patient and discuss whether this complication might be avoidable in the future.

Adenoma↗
PubMed2005

Concerted and sequential Coulomb explosion processes of N2O in intense laser fields by coincidence momentum imaging.

The Coulomb explosion dynamics of N2O in intense laser fields (800 nm, 60 fs, approximately 0.16 PWcm2) is studied by the coincidence momentum imaging method. From the momentum correlation maps obtained for the three-body fragmentation pathway, N2O3+-->N++N++O+, the ultrafast structural deformation dynamics of N2O prior to the Coulomb explosion is extracted. It is revealed that the internuclear N-N and N-O distances stretch simultaneously as the bond angle less than approximately N-N-O decreases. In addition, two curved thin distributions are identified in the momentum correlation maps, and are interpreted well as those originating from the sequential dissociation pathway, N2O3+-->N++NO2+-->N++N++O+.

Journal Article↗
PubMed2006

Explosive photodissociation of methane induced by ultrafast intense laser.

A new type of molecular fragmentation induced by femtosecond intense laser at the intensity of 2 x 10(14) W/cm2 is reported. For the parent molecule of methane, ethylene, n-butane, and 1-butene, fluorescence from H (n = 3-->2), CH (A 2Delta, B 2Sigma-, and C 2Sigma+-->X 2Pi), or C2 (d 3Pi g-->a 3Pi u) is observed in the spectrum. It shows that the fragmentation is a universal property of neutral molecule in the intense laser field. Unlike breaking only one or two chemical bonds in conventional UV photodissociation, the fragmentation caused by the intense laser undergoes vigorous changes, breaking most of the bonds in the molecule, like an explosion. The fragments are neutral species and cannot be produced through Coulomb explosion of multiply charged ion. The laser power dependence of CH (A-->X) emission of methane on a log-log scale has a slope of 10 +/- 1. The fragmentation is thus explained as multiple channel dissociation of the superexcited state of parent molecule, which is created by multiphoton excitation.

Journal Article↗
PubMed2002

Beyond the Rayleigh instability limit for multicharged finite systems: from fission to Coulomb explosion.

We address the stability of multicharged finite systems driven by Coulomb forces beyond the Rayleigh instability limit. Our exploration of the nuclear dynamics of heavily charged Morse clusters enabled us to vary the range of the pair potential and of the fissibility parameter, which results in distinct fragmentation patterns and in the angular distributions of the fragments. The Rayleigh instability limit separates between nearly binary (or tertiary) spatially unisotropic fission and spatially isotropic Coulomb explosion into a large number of small, ionic fragments. Implications are addressed for a broad spectrum of dynamics in chemical physics, radiation physics of ultracold gases, and biophysics, involving the fission of clusters and droplets, the realization of Coulomb explosion of molecular clusters, the isotropic expansion of optical molasses, and the Coulomb instability of "isolated" proteins.

Journal Article↗
PubMed2003

The complexity of alternative splicing of hagoromo mRNAs is increased in an explosively speciated lineage in East African cichlids.

The adaptive radiation of cichlid fishes in the lakes of East Africa is a prime example of speciation. The choice of cichlid mates on the basis of a variety of coloration represents a potential basis for speciation that led to adaptive radiation. Here, we characterize the cichlid homolog of the zebrafish hagoromo (hag) gene that was recently cloned and characterized from a pigmentation mutant. Although only one hag mRNA was reported in zebrafish, cichlids express nine different hag mRNAs resulting from alternative splicing. The hag mRNAs are expressed between the myotome and the epidermis where pigment cells are located, suggesting the cichlid hag gene is involved in pigmentation. The hag mRNA splicing pattern does not fluctuate among individuals from each of two species, suggesting that alternative splice site choice is fixed within species. Furthermore, cichlids in lineages that underwent explosive speciation expressed a greater variety of hag mRNAs than those in lineages that did not undergo such a degree of speciation, suggesting that species in the explosively speciated lineage acquired a complex regulatory mechanism of alternative splicing over a very short evolutionary period. Here, we provide an example in which alternative splicing may play a role in mate choice, leading to cichlid speciation through diversification of gene function by production of multiple mRNAs from a single gene.

Africa, Eastern↗
PubMed1982

Periodic explosions by positive feedback in a rising foam column.

An aqueous foam rising adiabatically in a column suffers a drop in temperature. Under appropriate conditions, such a column periodically explodes. We here trace this explosion to the tight thermal coupling between the foam and its enclosing glass column. When the surface surfactant concentration is unbuffered by micelles, a positive feedback exists between the flow of heat from the walls into the foam and the thermal conductivity of the foam itself. In our highly expanded foam, heat is conducted through the foam cells' interior primarily by the heat-pipe effect. Such an effect is retarded by a dense layer of surfactant molecules. Heat absorption causes cell expansion, which, in a foam unbuffered by micelles, causes a reduction in surface concentration of surfactant molecules and, hence, in an increase in thermal conductivity. This interpretation of our observed periodic explosions is in agreement with all of our observations.

Journal Article↗
PubMed1995

Could a nearby supernova explosion have caused a mass extinction?

We examine the possibility that a nearby supernova explosion could have caused one or more of the mass extinctions identified by paleontologists. We discuss the possible rate of such events in the light of the recent suggested identification of Geminga as a supernova remnant less than 100 parsec (pc) away and the discovery of a millisecond pulsar about 150 pc away and observations of SN 1987A. The fluxes of gamma-radiation and charged cosmic rays on the Earth are estimated, and their effects on the Earth's ozone layer are discussed. A supernova explosion of the order of 10 pc away could be expected as often as every few hundred million years and could destroy the ozone layer for hundreds of years, letting in potentially lethal solar ultraviolet radiation. In addition to effects on land ecology, this could entail mass destruction of plankton and reef communities, with disastrous consequences for marine life as well. A supernova extinction should be distinguishable from a meteorite impact such as the one that presumably killed the dinosaurs at the "KT boundary." The recent argument that the KT event was exceedingly large and thus quite rare supports the need for other catastrophic events.

Journal Article↗
PubMed1999

Acute and residual effects of vibratory stimulation on explosive strength in elite and amateur athletes.

Fourteen elite and 14 amateur athletes were subjected to vibratory stimulation during bilateral biceps curl exercises of explosive strength exertion. The athletes performed two separate series of three sets of exercises in random order. The second set of one series was administered with superimposed vibration of 44 Hz and an acceleration of about 30 m x s(-2) transmitted through the two-arms handle to the arm muscles. The mechanical power of each repetition was measured by the 'Power Teach' instrument. The maximal and mean power values for each set were automatically recorded and shown on the screen. The acute effect was evaluated as the difference between the mean and peak power output in the second (with vibratory stimulation) and first (without vibratory stimulation) sets. Similarly, the residual effect was taken to be the difference between the power values of the third (after vibratory stimulation) and the first (before vibratory stimulation) sets. The results were subjected to a repeated-measures analysis of variance with group as a between-participants factor. The results showed that exercise mode (with vs without vibratory stimulation) resulted in a significant immediate effect for mean power and for maximal power. The factor group (elite vs amateurs) resulted in a significant effect for maximal power only. The increase in explosive strength exertion attributed to vibratory stimulation was 30.1 and 29.8 W (10.4% and 10.2%) for maximal and mean power respectively in the elite group, and 20.0 and 25.9 W (7.9% and 10.7%) respectively in the amateur athletes. Vibratory stimulation resulted in an insignificant residual effect.

Adolescent↗