explosives
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The sensitivity to friction for a selection of primary explosives has been studied using a small BAM friction apparatus. The probit analysis was used for the construction of a sensitivity curve for each primary explosive tested. Two groups of primary explosives were chosen for measurement (a) the most commonly used industrially produced primary explosives (e.g. lead azide, tetrazene, dinol, lead styphnate) and (b) the most produced improvised primary explosives (e.g. triacetone triperoxide, hexamethylenetriperoxide diamine, mercury fulminate, acetylides of heavy metals). A knowledge of friction sensitivity is very important for determining manipulation safety for primary explosives. All the primary explosives tested were carefully characterised (synthesis procedure, shape and size of crystals). The sensitivity curves obtained represent a unique set of data, which cannot be found anywhere else in the available literature.
- MeSH
- faktografické databáze MeSH
- heterocyklické sloučeniny monocyklické MeSH
- krystalizace MeSH
- mikroskopie elektronová rastrovací MeSH
- peroxidy MeSH
- spektrofotometrie infračervená MeSH
- tření MeSH
- velikost částic MeSH
- vlhkost MeSH
- výbušné látky chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A novel portable device for fast and sensitive analysis of explosives in environmental samples is presented. The developed system consists of miniaturized microcolumn liquid chromatograph, photolytic converter and chemiluminescence detector. The device is able to determine selectively nitramine- and nitroester- and most of nitroaromates-based explosives as well as inorganic nitrates at trace concentrations in water or soil extracts in less than 8 min. The device allows to analyze various environmental samples such as soils or water materials without previous preconcentration. Because of internal power supply, the device ensures 12h of continuous operation. Limits of detection of compounds of interest are in the range of concentrations from 5.0 × 10(-9)M to 8.0 × 10(-5)M for a signal-to-noise ratio of 3. Limits of quantification are in the range of concentrations from 1.7 × 10(-8)M to 2.7 × 10(-4)M for a signal-to-noise ratio of 10. The repeatability of the method (RSD=2.9-5.6%) was determined by repeated injections (n=10) of the standard samples during 4h.
- MeSH
- aniliny analýza MeSH
- chromatografie kapalinová přístrojové vybavení metody MeSH
- dusičnany analýza MeSH
- kyselina peroxydusitá analýza MeSH
- luminiscenční měření MeSH
- nitrobenzeny analýza MeSH
- poměr signál - šum MeSH
- půda chemie MeSH
- voda chemie MeSH
- výbušné látky analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- exploze prevence a kontrola zákonodárství a právo MeSH
- lidé MeSH
- terorismus prevence a kontrola zákonodárství a právo MeSH
- urgentní zdravotnické služby organizace a řízení pracovní síly MeSH
- záchranné práce metody organizace a řízení pracovní síly MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Česká republika MeSH
In this paper, the decomposition reaction models and thermal hazard properties of 1,3,5-trinitro-1,3,5-triazinane (RDX) and its PBXs bonded by Formex P1, Semtex 1A, C4, Viton A and Fluorel polymer matrices have been investigated based on isoconversional and combined kinetic analysis methods. The established kinetic triplets are used to predict the constant decomposition rate temperature profiles, the critical radius for thermal explosion and isothermal behavior at a temperature of 82°C. It has been found that the effect of the polymer matrices on the decomposition mechanism of RDX is significant resulting in very different reaction models. The Formex P1, Semtex and C4 could make decomposition process of RDX follow a phase boundary controlled reaction mechanism, whereas the Viton A and Fluorel make its reaction model shifts to a two dimensional Avrami-Erofeev nucleation and growth model. According to isothermal simulations, the threshold cook-off time until loss of functionality at 82°C for RDX-C4 and RDX-FM is less than 500 days, while it is more than 700 days for the others. Unlike simulated isothermal curves, when considering the charge properties and heat of decomposition, RDX-FM and RDX-C4 are better than RDX-SE in storage safety at arbitrary surrounding temperature.
Invoking the known link between impact sensitivity and compressibility, we have expanded upon an earlier preliminary study of the significance of the available free space per molecule in the unit cell, ΔV. We express ΔV as V(eff) - V(int), where V(eff) corresponds to zero free space, V(eff) = molecular mass/density. V(int) is the intrinsic gas phase molecular volume. We demonstrate that V(int) can be appropriately defined as the volume enclosed by the 0.003 au contour of the molecule's electronic density; this produces packing coefficients that have the range and average value found crystallographically. Measured impact sensitivities show an overall tendency to increase as ΔV becomes larger. For nitramines, the dependence upon ΔV is rather weak; we interpret this as indicating that a single overriding factor dominates their initiation mechanism, e.g., N-NO(2) rupture. (An analogous situation appears to hold for many organic azides.) In addition to the conceptual significance of identifying ΔV as a factor in impact sensitivity, the present results allow rough estimates of relative sensitivities that are not known.
Úvod: Celosvětově je zábavní pyrotechnika používána především během oslav a svátků. S nárůstem jejího užívání dochází i ke vzrůstající četnosti úrazů. Petardy způsobují poranění oka trojím mechanismem: popálením, otřesením a výbuchem a průnikem cizích tělísek do oka. Incidence v různých státech se liší. Kazuistika: 49letému pacientovi při silvestrovské oslavě vystřelila petarda přímo do oka. Na Oční klinice FNHK byla provedena revize s nálezem dilacerace skléry a rohovky, ztráty uveální tkáně a čočky, hemorhagické ablace choroidey. Pooperačně byla podávána celková i lokální protizánětlivá terapie. Diskuze: Nejčastěji jsou postiženi mladí muži, kteří s petardami před úrazem přímo manipulují. Alkohol bývá prokázán v menšině případů. Většina poranění je mírných, asi jedna pětina úrazů je těžkých s následkem výrazného snížení zrakové ostrosti. Závěr: Oční úrazy petardou jsou vzácné, ale mohou způsobit velmi vážná poranění, které jsme popsali i v naší kazuistice. U našeho pacienta došlo k těžkému snížení zrakové ostrosti a omezení v osobním i pracovním životě.
Introduction: In different places across the world, bangers and explosives are used during celebrations and holidays. With increasing usage of fireworks increases also frequency of injuries. Explosives may cause three types of ocular injury: burns, blast or concussion effects and injuries related to foreign bodies penetrating into the eye. Incidence varies in different countries. Case: A 49-year-old man got injured during New Year’s Eve celebrations. A banger exploded directly into his left eye. At the Ophthalmology Clinic of University Hospital Hradec Králové a revision was conducted with finding of dilaceration of sclera and cornea, loss of uveal tissue and lens, haemorrhagic ablation of choroidea. Postoperatively systematic and local anti-inflammatory therapy was used. Discussion: Usually these injuries are most common at young men, who are actively working with explosives before getting hurt. Alcohol is proven in minority of cases. Most of the injuries are mild, about one fifth of injuries are severe with significant loss of vision. Conclusion: Ocular injuries from fireworks are rare but can result in a very serious condition, like we described in our case-report. Our patient’s injury resulted in severe loss of vision and problems not only in personal but also in professional life.
- Klíčová slova
- zábavní pyrotechnika,
- MeSH
- antiflogistika aplikace a dávkování terapeutické užití MeSH
- exploze * MeSH
- incidence MeSH
- lidé středního věku MeSH
- lidé MeSH
- popálení oka etiologie terapie MeSH
- poranění oka * etiologie chirurgie terapie MeSH
- úrazy v domácnosti MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The aim of this cross-sectional study was to examine relationships of external load variables between beach and indoor volleyball amongst individual positions on the team. The movements of eight beach and fourteen indoor female volleyball players were recorded during elite playoff matches; in total, 2,336 three-dimensional trajectories were analyzed. Time-outs and intervals between rallies or sets were excluded from active play time. In both beach and indoor volleyball, 80% of rallies lasted up to 10 s, and players covered 4.5 to 10 m of court during 60% of rally play. Differences in dependent variables of external load were found between independent variables of sports and player positions (p < 0.05). The distance covered in beach volleyball rallies and Player LoadTM parameters was significantly higher by up to 23%. The unstable court surface with sand in beach volleyball elevated explosive Player LoadTM (accelerations in all three orthogonal planes of motion higher than 3.5 m/s3) in beach volleyball players compared to those of players on stable flooring in indoor. While beach volleyball blocker and defender positions showed no significant difference in parameters between each other, they differed in all parameters when compared to player positions in indoor volleyball. Indoor blocker and libero reached higher loads than setter, outside and opposite positions in various parameters. Factors that influence external load include the larger relative court areas covered by each player in beach volleyball, complexity of players' roles, and game strategy. This data adds to the knowledge of elite match demands in female volleyball. Specified agility-drill distances and times are essential for training optimization and must be supported by scientific observation. Researchers, coaches, and conditioning specialists should find this helpful for achieving a higher degree of training regulation.
- MeSH
- lidé MeSH
- operantní podmiňování MeSH
- průřezové studie MeSH
- volejbal * MeSH
- výbušné látky * MeSH
- zrychlení MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
