Alaptide from synchrotron powder diffraction data

The title compound [systematic name: (8S)-8-methyl-6,9-diaza­spiro­[4.5]decane-7,10-dione], C9H14N2O2, consists of two connected rings, viz. a piperazine-2,5-dione (DKP) ring and a five-membered ring. The DKP ring adopts a slight boat conformation and the bonded methyl group is in an equatorial position. The five-membered ring is in an envelope conformation. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds link mol­ecules into chains running parallel to the c axis

Data RTG práškové difrakce monohydrátu dusičnanu tetrazenu, C2H9N11O4

X-ray powder diffraction data, unit-cell parameters, and space group for tetrazene nitrate monohydrate, C2H9N11O4, are reported [a = 5.205(1) Å, b = 13.932(3) Å, c = 14.196(4) Å, β = 97.826(3)°, unit-cell volume V = 1019.8(4) Å3, Z = 4, and space group P21/c]. All measured lines were indexed and are consistent with the P21/c space group. No detectable impurities were observed.Uvádíme rentgenová prášková difrakční data, parametry jednotkové buňky a prostorovou grupu pro monohydrát dusičnanu tetrazen, C2H9N11O4 [a = 5,205(1) Å, b = 13,932(3) Å, c = 14,196(4) Å, β = 97,826(3)°, objem jednotkové buňky V = 1019,8(4) Å3, Z = 4 a prostorová grupa P21/c]. Všechny naměřené čáry byly indexovány a odpovídají prostorové skupině P21/c. Nebyly pozorovány žádné detekovatelné nečistoty

The IR and Raman spectra of polyaniline adsorbed on the glass surface; comparison of experimental, empirical force field, and quantum chemical results

Vibrational spectra of the oligomeric models of polyaniline (PANI) were explored by quantum chemical and molecular mechanical tools. First, calibration calculations were performed on aniline sample where several computational models were compared with measured IR and Raman spectra. Based on this ‘calibration’, the ωB97XD/6-31G(d,p) level was used for optimization and spectra determination of powder polymer and PANI deposited on the glass surface. From the individual models of PANI it was found that spectral shape converge relatively fast with the length of oligomeric chain and octamers can be considered as the structures, which recover most of the spectral properties – both shape and intensities of individual peaks. As suggested by Stejskal, vibrational spectra provided by saturated chains consisting purely from aniline building blocks do not correlate with experimental values. However, the increasing amount of quinonic structures improves the agreement of computed spectra with experimental one substantially. The best correspondence occurs for the quinone:aniline ratio 1:3. This conclusion also follows from the fitted Raman spectrum calculated for the set of decameric structures – saturated and oxidized to three subsequent states (0, 2+, 4+, and 6+) where expansion coefficient of the 4+ state, which corresponds to two quinonic units clearly dominate.Web of Science57574

Dusičnan tetraamminměďnatý a jeho vlivy na dusičnan amonný

Tetraamminecopper(II) nitrate(V) (TACN) is a complex copper salt which is easily formed when ammonium nitrate (AN) comes into contact with copper. It is considered to be an unwanted contaminant of AN because of its sensitivity to mechanical stimuli and significant explosive properties. The formation of TACN by the reaction of copper with molten ammonium nitrate(V) was demonstrated by powder diffraction. Friction and impact sensitivity testing was performed and field experiments were then conducted to reveal the detonation parameters of TACN and its initiation capability towards ammonium nitrate. The dependence of the detonation velocity on charge diameter was revealed and the ideal detonation velocity of 3500 m.s(-1) at 0.87 g.cm(-3) was measured. AN with the addition of 16 wt.% of TACN was found to detonate when initiated with a small booster charge. Moreover, TACN was able to initiate detonation in fertilizer grade ammonium nitrate(V) under massive steel confinement. TACN should be therefore considered as a possible contributory initiation source in some large scale accidents. In this article, some properties of TACN are revealed which could be useful for the investigation of accidents.Dusičnan tetraaminměďnatý (TACN) je komplexní měďnatá sůl, která se snadno tvoří při styku dusičnanu amonného (AN) s mědí. TACN se považuje za nežádaný kontaminant dusičnanu amonného pro svou zvýšenou citlivost k mechanickým podnětům a vlastnosti výbušiny. Tvorba TACN reakcí mědi s roztaveným dusičnanem amonným byla prokázána práškovou difrakcí. Byly provedeny testy citlivosti ke tření a k nárazu a dále byly provedeny experimenty ke zjištění výbušinářských vlastností TACN a objasnění jeho iniciační schopnosti vůči dusičnanu amonnému. Byla popsána závislost detonační rychlosti na průměru nálože a byla změřena maximální detonační rychlost 3500 m.s(-1) při hustotě 0,87 g.cm(-3). Bylo zjištěno, že dusičnan amonný s přídavkem 16 % (hmot.) TACN detonuje při iniciaci malou počinovou náloží. Kromě toho je TACN schopen iniciovat dusičnan amonný v masivním ocelovém obalu. TACN by proto měl být považován za jeden z možných iniciačních zdrojů u některých velkých nehod. V tomto článku jsou popsány některé vlastnosti TACN, které by mohli být užitečné při vyšetřování nehod

Kracejici roboti lokalizuji miny.

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Effects of Ceramide and Dihydroceramide Stereochemistry at C‑3 on the Phase Behavior and Permeability of Skin Lipid Membranes

Ceramides (Cer) are key components of the skin permeability barrier. Sphingosine-based CerNS and dihydrosphingosine-based CerNdS (dihydroCer) have two chiral centers; however, the importance of the correct stereochemistry in the skin barrier Cer is unknown. We investigated the role of the configuration at C-3 of CerNS and CerNdS in the organization and permeability of model skin lipid membranes. Unnatural l-<i>threo</i>-CerNS and l-<i>threo</i>-CerNdS with 24-C acyl chains were synthesized and, along with their natural d-<i>erythro</i>-isomers, incorporated into membranes composed of major stratum corneum lipids (Cer, free fatty acids, cholesterol, and cholesteryl sulfate). The membrane microstructure was investigated by X-ray powder diffraction and infrared spectroscopy, including deuterated free fatty acids. Inversion of the C-3 configuration in CerNS and CerNdS increased phase transition temperatures, had no significant effects on lamellar phases, but also decreased the proportion of orthorhombic packing and decreased lipid mixing in the model membranes. These changes in membrane organization resulted in membrane permeabilities that ranged from unchanged to 5-fold higher (depending on the permeability markers, namely, water loss, electrical impedance, flux of theophylline, and flux of indomethacin) compared to membranes with natural CerNS/NdS isomers. Thus, the physiological d-<i>erythro</i> stereochemistry of skin Cer and dihydroCer appears to be essential for their correct barrier function

Analytická charakterizace improvizované výbušiny erythritol tetranitrátu

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [15N4] tetranitrate. In the case of powder diffraction, recently published data were verified, and 1H, 13C, and 15N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories.Ester kyseliny dusičné, erythritol tetranitrát (ETN) je bílá krystalická látka s charakterem brizantní výbušiny. Ačkoliv nikdy nenalezla průmyslové nebo vojenské využití, stala se jednou z nejčastěji vyráběných improvizovaných výbušin. Následující studie shrnuje výsledky analýzy několika analytických metod, které jsou využívány v kriminalistických laboratořích. Výsledky FTIR a Ramanovy apektrometrie rozšiřují doposud publikované výsledky přiřazením vibračních módů jednotlivým pásům ve spektru s využitím erythritol [15N4] tetranitrátu. Zároveň došlo k verifikaci nedávno publikovaných výsledků práškové difrakce a k detailní analýze 1H, 13C a 15N NMR spektra. Úspěšně byla rovněž technika tandemové hmotnostní spektrometrie s elektrosprejovou ionizací. Uvedené metody je možné využít k rychlé a spolehlivé detekci vzorků s obsahem erythritol tetranitrátu v kriminalistických laboratořích

Tetrazen–Characterizace jeho polymorfů

The reinvestigation of tetrazene single crystalline material by means of X-ray methods resulted in a slightly different structure when compared to previously published data. Reaction conditions responsible for different crystalline modification formation were investigated. Newly described C form was found to be the primary reaction product and the combined action of temperature and the presence of water over time is required for the transition to the A form. Both forms were described by X-ray powder diffraction. Tetrazene was also subjected to infrared and Raman spectroscopy, which allowed differentiating between the forms. The molecule was isotopically labeled with 15N atoms at two different locations (ring and nitrogen sidechain) and employed in assigning vibrational modes to the resulting bands. Differences between sensitivities to mechanical stimuli of the two modifications were investigated and found industrially insignificant. In the same vein, the performance of either modification in primer composition and primer was identical.Opětovné zkoumání tetrazenového monokrystalu pomocí rentgenových metod vedlo k mírně odlišné struktuře ve srovnání s dříve publikovanými údaji. Byly zkoumány reakční podmínky zodpovědné za odlišný vznik krystalických modifikací. Bylo zjištěno, že nově popsaná forma C je primárním reakčním produktem a pro přechod na formu A je nutné kombinované působení teploty a přítomnosti vody v čase. Obě formy byly popsány pomocí rentgenové práškové difrakce. Tetrazen byl rovněž podroben infračervené a Ramanově spektroskopii, což umožnilo formy rozlišit. Molekula byla izotopicky značena atomy 15N na dvou různých místech (kruh a postranní dusíkatý řetězec) a využita při přiřazování vibračních módů výsledným pásům. Byly zkoumány rozdíly mezi citlivostí obou modifikací na mechanické podněty, které byly shledány jako průmyslově nevýznamné. Podobně pak byla i funkčnost obou modifikací v zápalkových složích a zápalkách identická

Orthocuproplatinum, Pt 3 Cu, a new mineral from the Lubero region, North Kivu, Democratic Republic of the Congo

Orthocuproplatinum, Pt 3 Cu, is a new mineral from the Lubero region of North Kivu, Democratic Republic of the Congo. The mineral, which has a synthetic analogue, occurs as a 1.5-mm-long alluvial grain in a heavy-mineral concentrate, together with the holotype specimen of kitagohaite, Pt 7 Cu. The grain of orthocuproplatinum has a rim of hongshiite, PtCu, and abundant inclusions of calcite. Opaque and metallic, orthocuproplatinum has a whitish colour in reflected light and slightly perceptible anisotropy. The crystal structure of orthocuproplatinum is orthorhombic, space group Cmmm. Its unit-cell parameters: a = 7.681(1) Å; b = 5.4318(8) Å; c = 2.7502(4) Å; V = 114.74(3) Å 3 ;Z = 2. The calculated density is 17.866 g cm −3 .The strongest diffraction lines are [d in Å(I)]: 2.337 (11), 2.236 (100), 2.217 (97), 1.932 (61), 1.920 (30), 1.362 (36), 1.169 (24), 1.161 (23). The Vickers hardness is 243 kg mm −2 (VHN 25 ), corresponding to a Mohs hardness of 4. The empirical formula of orthocuproplatinum, calculated from a mean value of 12 electron-probe microanalyses that gave 12.9 wt% Cu and 87.3 wt% Pt, is Pt 2.76 Cu 1.24 on the basis of 4 atoms.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe