Thermal stability of an explosive detonator

Mercuric 5-nitrotetrazole is a possible replacement for lead azide. The thermal decomposition peak maximum ranged from 185 to 270°C as the heating rate increased from 0.1 to 100°C min⁻¹. The activation energy and frequency factor for thermal decomposition were determined from dynamic and isothermal DSC and isothermal TG data; the average values were 38.8 kcal mol⁻¹ and 3.56×10¹⁴ s⁻¹. A half-life experiment confirmed the kinetic constants and indicated that the decomposition reaction was first order. The heat of explosion was determined by a pressure DSC test and found to be 2587 J g⁻¹. The linear coefficient of expansion was 37±2×10⁻⁶°C⁻¹ from −60 to 160°C and indicated secondary transitions near −10 and 90°C. The specific heat was 0.0003154T+0.1339 in the region −40–90°C. The critical temperature for a slab with a half-thickness of 0.035 cm was calculated to be 232 °C.     

L-对甲苯磺酰乳酸乙酯合成物产率的化学分析法

建立了采用 K2 Cr O4 - K2 Cr2 O7混合指示剂测定 L-对甲苯磺酰乳酸乙酯合成物产率的化学分析方法 ,K2 Cr O4 - K2 Cr2 O7的最佳配比为 K2 Cr O4 ∶ K2 Cr2 O7=6∶ 1 (m/m) ,体系的最佳酸度为 p H5.8,测得 L-乳酸乙酯与甲苯磺酰氯反应制备的 L-对甲苯磺酰乳酸乙酯的产率为 94.0 %。     

Efficient Diketopyrrolopyrrole‐Based Small‐Molecule Bulk‐Heterojunction Solar Cells with Different Electron‐Donating End‐Groups

A series of small molecules that contained identical π‐spacers (ethyne), a central diketopyrrolopyrrole (DPP) unit, and different aromatic electron‐donating end‐groups were synthesized and used in organic solar cells (OSCs) to study the effect of electron‐donating groups on the device performance. The three compounds, DPP‐A‐Ph , DPP‐A‐Na , and DPP‐A‐An , possessed intense absorption bands that covered a wide range, from 350 to 750 nm, and relatively low HOMO energy levels, from ?5.50 to ?5.55 eV. DPP‐A‐An , which contained anthracene end‐groups, demonstrated a stronger absorbance and a higher hole mobility than DPP‐A‐Ph , which contained phenyl groups, and DPP‐A‐Na , which contained naphthalene units. The power‐conversion efficiencies (PCEs) of OSCs based on organic:PC₇₁BM blends (1:1, w/w) with a processed DIO additive were 3.93 % for DPP‐A‐An , 3.02 % for DPP‐Na , and 2.26 % for DPP‐A‐Ph . These findings suggest that a DPP core that is functionalized with electron‐donating capping groups constitutes a promising new class of solution‐processable small molecules for OSC applications.     

Balancing admission control,speedup, and waiting in service systems

Queueing Systems - Consider a population of customers, each of which needs to decide independently when to arrive to a facility that provides a service during a fixed period of time, say a day....     

Self-averaging radiative transfer for parabolic waves

A systematic derivations of self-averaging scaling limits of parabolic waves in terms of the Wigner distribution function is presented. The convergence of the Wigner distribution to one of the six deterministic radiative transfer equations is established. One of the main contributions of this Note is a unified framework for space–time scaling limits that lead to radiative transfer. To cite this article: A.C. Fannjiang, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Electrical Wavelength Switching of Ultrashort Pulses in a Mode-Locked Er-Doped Fiber Ring Laser with Fiber Gratings

Electrical wavelength switching of picosecond pulses was demonstrated in an actively mode-locked Er-doped fiber ring laser with fiber gratings by changing the electrical driving frequency of the modulator. Laser pulses switchable between two wavelengths spaced from 0.5 to 18 nm apart were achieved. The switching speed between the two wavelengths was of the order of several hundred kilohertz.     

Free surface Nvier-Stokes flows with simultaneous heat transfer and solidification/melting

A mathematical model to analyse some key aspects of the metal cast process is described involving the filling of the mould by liquid metal and simultaneously, undergoing both cooling and solidification (re-melting) phase change. A computational solution procedure based upon a finite volume discretisation approach, on both structured and unstructured meshes, is described. The overall flow solution procedure is based on the pressure correction algorithm SIMPLE suitably adapted to: (a) solve for the free surface with minimal smearing by the SEA algorithm, and (b) solve for the solidification/melting phase change using an enthalpy conservation algorithm developed by Voller, but with its root in the work of Crank many years ago.Dedicated to Professor J. Crank on the occasion of his 80th birthday     

A thermal analysis evaluation of the low temperature synthesis of BaBiO3

Thermal decomposition of metal-organic precursors for the mixed oxide BaBiO₃ was studied using TG and EGA. Precursors produced by polyesterification of bifunctional acids with ethylene glycol (Pechini process) decomposed about 100°C higher than those without the diol. BaCO₃ was identified by IR and XRD as a reaction intermediate. EGA proved that the amount of BaCO₃ was below 10% of the total barium, and that the barium exists mainly as a nitro-compound up to 650°C. Phase-pure BaBiO₃ with a moderately high surface area (1.4 m²/g) could be synthesised from a citrate precursor by the Pechini process at around 850°C.     

Use of p-nitrobenzyloxycarbonyl (pNZ) as a permanent protecting group in the synthesis of Kahalalide F analogs

p-Nitrobenzyloxycarbonyl (pNZ) is used for the permanent protection of ornithine in the synthesis of derivatives of the anti-tumor cyclodepsipeptide Kahalalide F that contain acid labile residues.