Strong External Electric Fields Reduce Explosive Sensitivity: A Theoretical Investigation into the Reaction Selectivity in NH2NO2∙∙∙NH3.

Controlling the selectivity of a detonation initiation reaction of explosive is essential to reduce sensitivity, and it seems impossible to reduce it by strengthening the external electric field. To verify this, the effects of external electric fields on the initiation reactions in NH2NO2∙∙∙NH3, a model system of the nitroamine explosive with alkaline additive, were investigated at the MP2/6-311++G(2d,p) and CCSD(T)/6-311++G(2d,p) levels. The concerted effect in the intermolecular hydrogen exchange is characterized by an index of the imaginary vibrations. Due to the weakened concerted effects by the electric field along the -x-direction opposite to the "reaction axis", the dominant reaction changes from the intermolecular hydrogen exchange to 1,3-intramolecular hydrogen transference with the increase in the field strengths. Furthermore, the stronger the field strengths, the higher the barrier heights become, indicating the lower sensitivities. Therefore, by increasing the field strength and adjusting the orientation between the field and "reaction axis", not only can the reaction selectivity be controlled, but the sensitivity can also be reduced, in particular under a super-strong field. Thus, a traditional concept, in which the explosive is dangerous under the super-strong external electric field, is theoretically broken. Compared to the neutral medium, a low sensitivity of the explosive with alkaline can be achieved under the stronger field. Employing atoms in molecules, reduced density gradient, and surface electrostatic potentials, the origin of the reaction selectivity and sensitivity change is revealed. This work provides a new idea for the technical improvement regarding adding the external electric field into the explosive system.

Experimental and theoretical investigation into the response to shock wave for booster explosives JO9C, JH14, JH6, and insensitive RDX.

In order to reduce the vulnerability, the responses to shock waves for booster explosives JO9C, JH14, JH6, and insensitive RDX were evaluated using shock wave partition loading test. To explain the experimental results, molecular dynamics simulation, intermolecular interaction and bond dissociation energy (BDE), and shock initiation pressures were evaluated using the B3LYP, MP2 (full), and M06-2X methods with the 6-311 + + G(2df,2p) basis set. The order of the responsivity is JO9C > JH14 > JH6 > insensitive RDX. The binding energies follow the order of JH14* ≈ JO9C* < insensitive RDX* < JH6*. The interaction energies and BDEs are in RDX∙∙∙(CH3COOCa)+ > RDX∙∙∙CH3COOH > RDX∙∙∙CH2FCH2F. Thus, it can be inferred that for the RDX-based explosives, the stronger the binding energy, intermolecular interaction, and BDE are, the more insensitive the booster is, and thus, the larger energy has to be consumed to overcome the above three kinds of energies during the initiation process, leading to the smaller energy output and weaker response. However, it should be noted that it is mainly the density and the type of explosive that influence the depth of the dent produced on the steel witness block. The essence of the responses to shock waves is revealed by the reduced density gradient, atoms in molecules, and surface electrostatic potentials. HIGHLIGHTS: • Response of booster to shock wave was evaluated by shock wave partition loading test. • Responsivity to shock wave is explained by binding energy, intermolecular interaction, and BDE. • Shock initiation pressures were evaluated. • Essence of responses to shock wave is revealed by RDG, AIM and ESP.

Glycated albumin based photonic crystal sensors for detection of lipopolysaccharides and discrimination of Gram-negative bacteria.

We present two types of two-dimensional (2D) photonic crystals (PC) hydrogel sensors based on glycated albumin (G-alb) as a proof-of-concept for utilizing recognition between G-alb and bacterial cell surface lipopolysaccharides (LPS) to detect and discriminate Gram-negative bacteria. The G-alb functionalized PC-G-alb hydrogel provides recognition of different LPS via hydrogen bonding and can discriminate different Gram-negative bacteria based on their LPS types. The hydrogel delivered LOD of 0.87 ng mL-1 for E.coli LPS, 153 CFU mL-1 for E.coli, 1.22 ng mL-1 for P.aeruginosa LPS and 225 CFU mL-1 for P.aeruginosa. On the other hand, LPS bioimprinted hydrogel (PC-G-alb-LPSimp) provides selective recognition of E.coli LPS with LOD 0.76 ng mL-1 and for E.coli 58 CFU mL-1, via generation of flexible specific cavities for E.coli and its LPS. The two hydrogels showed remarkable recoveries for both LPS and Gram-negative bacteria in the relevant samples of milk, orange juice, river water, and serum with a short response time of 6-12 min. In the binding process, the hydrogels shrink, and 2D PC particle spacing decreases with diffraction shift from green to blue. The diffraction shifts can be visually observed, measured through Debye's diffraction ring diameter by a laser pointer or determined from a spectrometer.

Development of Molecularly Imprinted 2D Photonic Crystal Hydrogel Sensor for Detection of L-Kynurenine in Human Serum.

l-Kynurenine (KYN) is a metabolite of the Kynurenine pathway and is a known potential marker of immune suppressant disorders and cancer. Here, we present a molecularly imprinted two dimensional (2D) Photonic crystal (PC) hydrogel sensor for the detection of L-KYN in human serum. The sensor utilizes polystyrene-based 2D PC colloidal arrays (2D PCCA) hydrogel with methacrylic acid as the functional monomer which can imprint the L-KYN template by hydrogen bonding. After removal of the template, the resulting nanocavities in the hydrogel can selectively bind and recognize L-KYN in the serum samples. The binding is selective for L-KYN, which is revealed by shrinkage of the hydrogel volume and decrease in the particle spacing that can be easily monitored through changes in the Debye diffraction ring diameter using a LASER pointer. The sensor demonstrates visible red to green color shift upon binding to L-KYN. The 2D PC sensor demonstrates the limit of detection (LOD) of 50  nM, linear relationship of particle spacing versus L-KYN concentration range (50-1000  nM) with the analytical recovery of up to 92 % in the spiked serum samples. The sensor can distinguish between L-KYN and D-KYN and is re-usable up to five times. The sensor is available for the rapid and quantitative detection of L-KYN in the human serum.

Separation of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane and 1,3,5-trinitro-1,3,5- triazacyclohexane by molecularly imprinted solid-phase extraction.

Synthesis of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane and 1,3,5-trinitro-1,3,5-triazacyclohexane by the Bachmann process leads to a mixture of both. The separation of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane and 1,3,5-trinitro-1,3,5-triazacyclohexane from their mixture is difficult because the sizes and physical properties of these homologous compounds are similar. For this purpose, seven molecularly imprinted polymers have been synthesized for each explosive, and a selective solid-phase extraction procedure has been developed. A molecularly imprinted polymer, synthesized with 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane as the template, methacrylic acid as the monomer and trimethylolpropane trimethacrylate as the cross-linking agent in a molar ratio of 1:8:8 showed the best separation capability. A packed cartridge containing this polymer can be reused for 23 solid-phase extraction cycles without repacking, and the total separation capability toward 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane reached 6.81 mg per gram of polymer. 1,3,5-Trinitro-1,3,5-triazacyclohexane was not detected in the separated 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane by high-performance liquid chromatography and vice versa. This newly developed method had the advantages of high recovery (100%) and purity, environmental friendliness, and room temperature operability. This study showed that some molecularly imprinted polymers that cannot absorb target analytes well in the solvent in which the polymers were polymerized might have high-binding capacity for the analytes and show imprinting effects in other solvents.

Synthesis of novel pleuromutilin derivatives. Part 1: preliminary studies of antituberculosis activity.

The worldwide threat from tuberculosis (TB) has resulted in great demand for new drugs, particularly those that can treat multidrug-resistant TB. We synthesized novel pleuromutilin derivatives with N-benzylamine side chain substituted at the C14 position and evaluated their activity in vitro against a virulent strain of Mycobacterium tuberculosis (H37Rv). The primary assay results showed that five compounds inhibited the H37Rv at 20µM, with a MIC of one of the analogues as low as 7.2µM.

[Middle segment pancreatectomy for the benign tumors of the neck and body of the pancreas (report of 15 cases)].

OBJECTIVE: To study the clinical application value of middle segment pancreatectomy in the treatment of benign tumors of the amphi-neck of the pancreas. METHODS: Fifteen cases were retrospectively analyzed treated from November 2005 to June 2009. There were 3 male and 12 female aging from 30 to 50 years. They all received middle segment pancreatectomy for benign tumors of the amphi-neck of the pancreas. RESULTS: There was no death during perioperative period. All the 15 patients received middle segment pancreatectomy. Fourteen of them received the closure of broken ends of pancreatic head, pancreaticojejunostomy (mono-anastomosis) and the rest one received dipl-anastomosis. Postoperative pathology showed that in the 15 patients, 1 got solid-pseudopapillary tumor of the pancreas, 3 got non-functional islet cell tumor, 11 got cystadenoma of pancreas. Three of them got pancreatic fistula and were self cured in 3 months. Follow-up visits to all the patients kept in the following 2 to 45 months. There was no death. No patients got new-onset diabetes and pancreatic pseudocyst. And their tumors were not relapsed. CONCLUSIONS: There is an exact therapeutic effect of middle segment pancreatectomy for benign tumors of the amphi-neck of the pancreas. The treatment has little function damage to patients' endocrine and external secretion. The incidence rate of pancreatic fistula in middle segment pancreatectomy is higher than that in pancreaticoduodenectomy. As long as the drainage is kept unobstructed, most of the pancreatic fistula can be self cured.

[Gene therapy targeting for carcinoma regulated by E2F-1 promoter].

OBJECTIVE: To study the selective effect to tumor cells mediated by a recombinant adenoviral vector carrying E2F-1 promoter. METHODS: The AdEasy-1 adenoviral vector system was used in this experiment. Several recombinant adenovirus with tumor-targeting E2F-1 promoter were constructed and then the E2F-1 promoter gene was checked by PCR and sequencing. The two adenovirus expressing GFP gene which is regulated by E2F-1 promoter or CMV promoter were used to respectively transfect tumor cells and non-proliferating normal cells, then observed and analyzed the different results caused by different promoters. Vpr gene was cloned into the targeting recombinant adenovirus. The new adenovirus named rvAdE2F-1/vpr was used to transfect tumor cells SMMC-7721, LS174T and non-proliferating normal cells H292, L-02. The surviving rate of each group was registered; the level of E2F-1 protein expressed in normal and tumor cell lines were checked by Western Blot. RESULT: E2F-1 promoter can regulate the downstream gene GFP selectively expressed in LS174T and its activity in LS174T was similar with CMV promoter's; Vpr gene regulated by E2F-1 promoter can suppress the proliferation of tumor cells and no toxicity to normal cells; In all of the tumor cells, a much higher level of E2F-1 was expressed compared with normal cell lines. E2F-1 promoter's activity correlated well with E2F-1 protein levels. CONCLUSIONS: E2F-1 promoter can control a selective cell killing to cancer cells, with no effect to normal cells. The system of E2F-1 promoter is a useful method for tumor-targeting gene therapy.