Research Department Explosive Research Articles

Theoretical and experimental study of bubble dynamics in underwater explosions

The development of analytical theory and experimental methods for understanding the correlation between the explosive properties and bubble dynamic characteristics in underwater explosions has important engineering application value for underwater weapons and ships. Based on the assumption of an instantaneous explosive detonation, we introduced the Jones–Wilkins–Lee equation of state to describe the high-pressure state in an explosion bubble and established the initial conditions for the bubble dynamics calculations. Considering the high-Mach-number flow and high pressure at the initial boundary of the explosion bubble, the Lezzi–Prosperetti equation with second-order Mach accuracy was used. Thus, an analytical model and a calculation method of the explosion bubble dynamics for an explosive detonation were established. This direct link between the detonation parameters and the bubble features is significant for the subtle design, selection, and optimization of explosives' properties. A micro-equivalent explosive bubble pulsation experiment was carried out in a water tank using a customized experimental system, which can offer nearly boundary-free condition to mitigate the reflective wave effects on bubbles. Three types of explosives were used in the experiment: the Research Department explosive (RDX), the Pentaerythritol tetranitrate (PETN), and the Hexanitrohexaazaisowurtzitane (CL20). Finally, the experimental results and the practicability of the experimental system were analyzed. The influence of the explosive type on the dynamic characteristics of the explosion bubbles and the differences between the theoretical and experimental results were compared. The results showed that the proposed explosion bubble dynamics model and calculation method have high accuracy and practicability. The proposed model can be used for explosives with known detonation parameters and equation of state parameters. The detonation parameters, velocity, and pressure are linked to the bubble features pulsation period and the maximum radius directly. The designed experimental system, which is capable of simulating an infinite water for the explosion of micro-equivalent explosives, was stable and easy to use. The work is significant for the subtle design, selection, and optimization of explosives' properties.

Polydopamine-based molecularly imprinted thin films for electro-chemical sensing of nitro-explosives in aqueous solutions

A sensitive electrochemical sensor was developed for the detection of nitro-explosives in aqueous solutions based on thin molecularly imprinted polydopamine films. Dopamine was identified in silico, based on DFT (density functional theory) calculations with the ωB97X-D/6-31G* basis set, as the best functional monomer and electropolymerized via cyclic voltammetry (CV) in the presence of carboxylic acid-based structural analogues ('dummy' templates) for two model nitro-explosives: TNT (2,4,6-trinitrotoluene) and RDX (Research Department eXplosive, 1,3,5-trinitroperhydro-1,3,5-triazine). This approach afforded a homogenous coverage of gold electrodes with imprinted films of tunable thickness. The electropolymerized molecularly imprinted polydopamine films allowed for a 105-fold sensitivity improvement over a bare gold electrode based on tracking the redox peaks of the targets by CV. This improved sensitivity is ascribed to the ability of the MIP to concentrate its target in proximity to the transduction element. The MIP films showed reproducible binding in phosphate buffer (10 mM, pH 7.4), with a dynamic range from 0.1 nM to 10 nM for both TNT and RDX and an increased selectivity over closely related structural analogues.

Ecotoxicological response of Scenedesmus obliquus to pure energetic compounds and metal ions found in wastewater streams from munitions manufacturing

The energetic compounds 1-methoxy-2,4-dinitrobenzene (DNAN), nitroguanidine (NQ), 3-nitro-1,2,4-triazole-5-one (NTO) and 1,3,5-trinitro-1,3,5-triazinane (Research Department Explosive, RDX) are widely used for explosive formulations production. Wastewater streams from industrial munition facilities are rich in nitrogen and contain considerable amounts of residual energetic compounds and metals such as zinc, nickel and copper. As such, these wastewater streams require physicochemical and/or biological treatment to meet regulatory discharge limits. The high nitrogen content of these streams makes them an attractive nutrient source for growing biomass such as microalgae. In previous studies we have identified some wastewater streams suitable for microalgal growth with minimal or no prior treatment, while others have shown moderate to high growth inhibition. The current study aims to elucidate the toxicity response of microalgae by performing growth-inhibition assays using solutions of single compounds and mixtures of energetic compounds and heavy metals. Using the freshwater green microalga Scenedesmus obliquus (S. obliquus) (ATCC® 11477) as a model organism, a microwell-plate growth-inhibition test procedure was performed to assess potential growth inhibition effects by DNAN, NQ, NTO, RDX, Zn, Ni and Cu. For the three metals tested, the order of growth rate inhibition effect on S. obliquus was Ni > Cu > Zn. The EC50s of Ni, Cu and Zn for S. obliquus were 0.08 mg/L, 0.26 mg/L and 10.13 mg/L, respectively. The effective concentrations for 50% growth inhibition (EC50) were 4.86 mg/L for DNAN and 8,700 mg/L for NTO. Conversely, RDX exhibited no toxicity below its solubility limit, and NQ had a mild toxic effect on S. obliquus with an EC20 of 303.3 mg/L.

NTO Sensing by Fluorescence Quenching of a Pyoverdine Siderophore-A Mechanistic Approach.

In this study, a siderophore, pyoverdine (PVD), has been isolated from Pseudomonas sp. and used to develop a fluorescence quenching-based sensor for efficient detection of nitrotriazolone (NTO) in aqueous media, in contrast to other explosives such as research department explosive (RDX), picric acid, and trinitrotoulene (TNT). The siderophore PVD exhibited enhanced fluorescence quenching above 50% at 470 nm for a minimal concentration (38 nM) of NTO. The limit of detection estimated from interpolating the graph of fluorescence intensity (at 470 nm) versus NTO concentration is found to be 12 nM corresponding to 18% quenching. The time delay fluorescence spectroscopy of the PVD–NTO solution showed a negligible change of 0.09 ns between the minimum and maximum NTO concentrations. The in silico absorption at the emission peak of static fluorescence remains invariant upon the addition of NTO. The computational studies revealed the formation of inter- and intramolecular hydrogen-bonding interactions between the energetically stable complexes of PVD and NTO. Although the analysis of Stern–Volmer plots and computational studies imply that the quenching mechanism is a combination of both dynamic and static quenching, the latter is dominant over the earlier. The static quenching is attributed to ground-state complex formation, as supported by the computational analysis.

Laboratory experiment of stemming impact on rock fragmentation by a high explosive

Ten blasts with cylindrical granite specimens were carried out in four groups with different specific charges and different constraint conditions. All rock specimens came from a granite quarry and they were cylinders with a diameter of 240 mm and a length of 300 mm. Three specific charges—0.2, 0.3 and 0.6 kg/m3 with Research Department Explosive (RDX) as a package charge—were used, and two constraint conditions were tested. In the first constraint condition the rock specimen had a free surface, but a larger steel tube was placed outside the specimen; in the second one the specimen had a free surface and there was no steel tube or other obstacle outside the specimen. Each group included at least one specimen with stemming and at least one without stemming. During blasting, a high-speed camera was used to film the blasting process, and after each blast all fragments including fine materials were collected, sieved and analyzed. The results indicated that: (1) stemmed blasts yielded much better (finer) fragmentation than unstemmed blasts at a constant specific charge, (2) unstemmed blast wasted at least 25% explosive energy in fragmentation, compared with stemmed blasts, and (3) higher specific charge resulted in better fragmentation in either stemmed blasts or unstemmed ones.

The Secret History of RDX: The Super-Explosive That Helped Win World War II by Colin F. Baxter

Reviewed by: The Secret History of RDX: The Super-Explosive That Helped Win World War II by Colin F. Baxter Rich Hamerla (bio) The Secret History of RDX: The Super-Explosive That Helped Win World War II. By Colin F. Baxter. Lexington: University Press of Kentucky, 2018. Pp. x+204. $45. In The Secret History of RDX: The Super-Explosive That Helped Win World War II, Colin F. Baxter presents the story of the development of RDX (Research Department Explosive), which begins at the Woolrich Arsenal in London in 1941. Baxter hopes this study will contribute to the “History from the Middle” of the Second World War, as opposed to the usual accounts that focus on activity at the top (leadership and campaigns), or the bottom (small-unit histories and solider/sailor biographies). The story takes us from London to Canada and, most importantly, to the Holston Ordinance Works near Kingsport, Tennessee, United States. The British, looking to procure a more powerful explosive for the war, achieved this by working with its own scientists and military personnel and with her allies in Canada and the United States. While initially developed to replace older explosives used in bombs—Amatol—which made up approximately 30 percent of the munitions’ weight when an equivalent German bomb was 50 percent explosive by weight, RDX and its spinoffs were, the author argues, on par with more familiar technologies that helped in the war for the Allies. RDX-based products such as Composition B2 and C-4 were used in a variety of applications, including the biggest non-nuclear air-dropped bombs during the war: the 14,000 pound Tallboys and the 22,000 pound Grand Slams. Torpex, another RDX byproduct, was a crucial ingredient used in confronting the U-Boat threat to Great Britain. Baxter commits an entire chapter to this subject, which is arguably the best in the book. Baxter emphasizes familiar themes in the history of the relationships between governments, modern militaries, science, and technology. For example, all Allied militaries were skeptical of civilian scientists’ ability to understand military needs, which was coupled with a military culture characterized by a pervasive anxiety over secrecy. This caused friction between various ordinance personnel, government research committees, and civilian-dominated councils. In the end, though, relationships smoothed and the Tennessee Eastman Company was hired to develop RDX production processes, which it did on a massive scale, from a production output of 60 tons a week by British manufacturing in 1941 to 340 tons per day in the United States by the end of the war. While an interesting and useful book from a scholarly perspective, The Secret History of RDX also includes several anecdotes that many military veterans will find familiar and amusing, this reviewer included. One occurred in 1944 when bomber crews were taken in by a rumor begun by senior [End Page 366] officers concerned over mishandling the new RDX-based munitions. This led young bomber crews to believe that Composition B2 (RDX) bombs were exceptionally fragile and prone to exploding if handled too roughly. On one particularly turbulent mission to Germany on 20 April, the nervous bombardiers dumped 2,472 of 6,344 bombs into the English Channel rather than risk delivering them to their targets. Based on this and similar incidents, ordnance officers and crews were then told to disregard information that suggested RDX bombs required special, delicate handling. The outcome of this change-in-message resulted in a predictable fiasco just a few months later when, on 15 July, a detail of American airmen found themselves delivering a load of 500-pound bombs to an ammo dump in Suffolk, England on a Saturday night. The young men, sure the munitions were safe and anxious to complete their work before a night on the town, disregarded standard unloading procedures. The driver of one of the trucks put the vehicle in reverse, gunned the engine and slammed on the breaks, jettisoning the cargo onto the tarmac. The crew was successful in quickly unloading the bombs, but in doing so, 12,000 tons of RDX-based explosives went off, killing five airmen in an explosion that could be heard miles away. Generally, then, this...

Prediction of energetic properties of carboranyl tetrazoles based on DFT study

Compounds which are rich in boron and nitrogen have the potential to find application as high-energy material. In the present article quantum-chemical calculations (DFT B3LYP/6-311 + G*) of geometric and electronic structures, enthalpies of formation, highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO) energies and the detonation properties of 22 molecules of carboranyl tetrazoles were carried out. The method of the estimation of enthalpies of formation of carboranyl tetrazoles based on full energies of the molecules and semi empirical parameters for solid carbon (graphite) and boron was proposed. The enthalpies of formation of carboranyl tetrazoles were evaluated. Theoretical terahertz frequencies for potential high-energy density materials (HEDMs) were computed which allows the opportunity for the remote detection of these compounds. According to the results of calculations the most promising HEDMs among studied compounds were found to be 9,12-bis(2-(5-phenyl-tetrazol-2-yl)propyl)-o-carborane; 9,10-bis(2-(5-phenyl-tetrazol-2-yl)propyl)-m-carborane; 5,5’-(butan-1,4-diyl)-{9,12-bis[2-(tetrazol-2-yl)prop-1-yl]-о-carborane}. Based on the calculated frontier molecular orbital energy gap these energetic materials are even less impact sensitive than classical diaminotrinitrobenzene (DATB) and trinitroaniline (TNA). These compounds are characterized by the maxima magnitudes of the evaluation of the enthalpies of formation (EOF) and can be considered as promising HEDMs as their EOF values are notably higher than those of well-known trinitrotoluene (TNT) and hexogen (RDX, Research Department eXplosive).

Status epilepticus after C-4 ingestion: using liquid chromatography to quantify toxicity

Context: C-4, a commonly used explosive in military operations, is sometimes consumed by soldiers as a rite of passage. The primary component of C-4 is cyclotrimethylenetrinitramine, or Research Department Explosive (RDX), which causes euphoria along with nausea, vomiting, renal injury, encephalopathy and convulsions when consumed in toxic amounts. We present a case of status epilepticus caused by known ingestion of C-4, in which serum levels of the compound were measured with high-performance liquid chromatography (HPLC).Case details: A 22-year-old active-duty male with no prior medical history was brought to the ED with convulsions that only minimally improved traditional anti-epileptic treatment. EEG showed persistent epileptiform activity despite initial management. Continuous propofol infusion, lacosamide and levitiracetam eventually broke the seizures. The patient eventually reported consuming a piece of C-4 four hours prior to the start of his seizure activity.Results: HPLC showed a peak RDX concentration of 3.06 μg/ml. RDX concentration at cessation of seizure activity was 2.43 μg/ml.Conclusion: Per our review of the literature, this is the first case where the explosive's toxicity could directly be measured over time in a human patient. C-4 poisoning must be considered when assessing sudden onset epileptiform activity in soldiers with access to this substance.

Trace detection of research department explosive (RDX) using electrochemical gas sensor

Scientific interest in the detection of the high-explosive research department explosive (RDX) continues to escalate from a national security perspective. In this article, selective and sensitive detection of trace RDX is demonstrated. The screening system is based on a concentrator front end and electrochemical potentiometric gas sensor as the backend. Preferential hydrocarbon and nitrogen oxide(s) mixed potential sensors with integrated heaters were used to capture the signature of the explosive. Quantitative measurements based on hydrocarbon and nitrogen oxide sensor responses indicated that the detector sensitivity scaled proportionally with the mass of RDX (down to 20ng). The sensitivity was found to depend on the flow rate. The sensitivity was found to increase with increasing flow rate. A 42% increase in sensitivity was observed with a flow rate of 500ml/min. This detection technique has the potential to become an orthogonal technique to the existing explosive screening technologies for reducing the number of false positives/false negatives in a cost-effective manner.

Chemical ionization mass spectrometry using carbon nanotube field emission electron sources.

A novel chemical ionization (CI) source has been developed based on a carbon nanotube (CNT) field emission electron source. The CNT-based electron source was evaluated and compared with a standard filament thermionic electron source in a commercial explosives trace detection desktop mass spectrometer. This work demonstrates the first reported use of a CNT-based ion source capable of collecting CI mass spectra. Both positive and negative modes were investigated. Spectra were collected for a standard mass spectrometer calibration compound, perfluorotributylamine (PFTBA), as well as trace explosives including trinitrotoluene (TNT), Research Department explosive (RDX), and pentaerythritol tetranitrate (PETN). The electrical characteristics, lifetime at operating pressure, and power requirements of the CNT-based electron source are reported. The CNT field emission electron sources demonstrated an average lifetime of 320 h when operated in constant emission mode under elevated CI pressures. The ability of the CNT field emission source to cycle on and off can provide enhanced lifetime and reduced power consumption without sacrificing performance and detection capabilities. Graphical Abstract ᅟ.

Binding of RDX to Cell Wall Components of Pinus sylvestris and Picea glauca and Three-Year Mineralisation Study of Tissue-Associated RDX Residues

Contamination of soils with the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, Research Department Explosive) as a result of military applications is a large-area problem globally. Since coniferous trees dominate the vegetation of large areas of military land in Central Europe, particularly in Germany, the long-term fate of 14C-RDX in the conifers Scots pine and Dwarf Alberta spruce was studied. Acetic acid was the most effective solvent for the removal of extractable RDX residues from homogenates of RDX-laden tree material (85%, 80–90% and 64–80% for roots, wood and needles, respectively). On average, only a fifth of RDX-derived 14C was bound in non-extractable residues (NER). Within the main cell wall compartments, lignin was the dominant binding site for NER (needles: 32–62%; roots: 38–42%). Hemicellulose (needles: 11–18%; roots: 6–11%) and cellulose (needles: 12–24%; roots: 1–2%) were less involved in binding and a considerable proportion of NER (needles: 15–24%; roots: 59–51%) was indigestible. After three-year incubation in rot chambers, mineralisation of tree-associated 14C-RDX to 14CO2 clearly dominated the mass balance in both tree species with 48–83%. 13–33% of 14C-RDX-derived radioactivity remained in an unleachable form and the remobilisation by water leaching was negligible (< 2%).

상세 모델링을 통한 RDX 연소 동특성 분석

수명이 도래한 고에너지물질의 처리를 위해 환경오염 및 안전성, 처리용량 등을 고려해야 하며, 현재 가장 주목 받고 있는 처리방식은 소각처리공정이다. 그러나 처리대상 고에너지물질의 종류가 매우 다양하고, 특성 또한 다르기 때문에 범용적 기술개발이 힘든 실정이다. 본 연구는 상세 수학적모델링 및 동적모사를 통하여 가장 널리 사용되는 고에너지물질의 하나인 고폭약(research department explosive, RDX)을 플러그흐름반응기(plug flow reactor, PFR)에서 소각 시 반응기 내부의 물리-화학적 변화를 예측하였다. 본 연구에서 사용된 RDX반응은 263개의 상세한 기초반응식으로 이루어져 있으며 43개의 성분이 반응에 관여한다. 모사결과 반응기 내부온도를 제어하여 RDX의 민감성을 통제할 수 있었다. 반응기 내부온도를 1,200 K로 유지 할 때 RDX는 분해반응만 일어나 폭발과 같은 큰 에너지 방출을 막을 수 있었으나 공급되는 열원이 높아져 1,300 K이상 반응기 온도가 증가 시에는 3,000 K 이상의 온도상승을 수반하는 발화반응이 일어났다. 본 연구를 통하여 반응기의 운전온도변화에 따른 RDX반응 특성을 제시함으로써 효율적인 RDX소각로 공정설계 및 운전에 기초가 될 것으로 사료된다. In the treatment of spent high energetic materials, the issues such as environmental pollution, safety as well as working capacity should be carefully considered and well examined. In this regard, incineration has been recommended as one of the most promising processes for the disposal of such explosives. Due to the fact that high energetic materials encompass various types and their different characteristics, the technology development dealing with various materials is not an easy task. In this study, rigorous modeling and dynamic simulation was carried out to predict dynamic physico-chemical phenomena for research department explosive (RDX). Plug flow reactor was employed to describe the incinerator with 263 elementary reactions and 43 chemical species. Simulation results showed that safe operations can be achieved mainly by controlling the reactor temperature. At 1,200 K, only thermal decomposition (combustion) occurred, whereas increasing temperature to 1,300 K, caused the reaction rates to increase drastically, which led to ignition. The temperature further increased to 3,000 K which was the maximum temperature recorded for the entire process. Case studies for different operating temperatures were also executed and it was concluded that the modeling approach and simulation results will serve as a basis for the effective design and operation of RDX incinerator.

고농축 복합화약 시뮬란트: Exact/Dechlorane 현탁계의 유변물성

에너지 고분자인 poly(BAMO-AMMO)와 유사한 특성을 갖는 폴리에틸렌 플라스토머인 Exact를 고분자 결합제로, RDX(research department explosive)와 유사한 특성을 갖는 dechlorane을 충전제로 사용한 고농축 복합화약 시뮬란트 현탁계의 유변물성을 연구하였다. 회분식 용융혼련기를 사용하여 현탁계의 혼화거동을 조사하였는데 상당한 점성소산열이 발생하였다. 충전율이 70 v% 이상에서는 토크의 지속적인 감소가 있었는데 이는 벽면 미끌어짐 현상에 기인한다고 사료되었다. SEM 관찰 결과 충전제 입자들은 잘 분산되어 있었고 혼화 조건의 영향은 크지 않은 것으로 판단되었다. 현탁계의 뚜렷한 전단박화(shear thinning) 특성으로 인하여 낮은 전단속도의 평판-평판 레오미터에서 측정이 어려운 고충전 현탁계도 높은 전단속도의 모세관 레오미터에서 유변물성 측정이 가능하였다. The rheology of highly concentrated polymer bonded explosive (PBX) simulant was studied. An energy material, polyethylene plastomer (Exact<TEX>$^{TM}$</TEX>) having similar properties to poly(BAMO-AMMO) was selected as a binder. Dechlorane with similar properties to RDX (Research Department eXplosive) was chosen as a filler. Mixing behavior in a batch melt mixer was investigated. During mixing a large amount of heat of viscous dissipation was generated and a continuous decrease in torque was observed when the filler content was above 70 v%. It was believed due to wall slip phenomena. From the SEM images, the fillers were well dispersed and the effect of mixing condition affected slightly on the dispersion. Owing to distinct shear thinning behavior of the suspensions, measuring viscosity of highly filled suspensions was possible in a high shear rate capillary rheometer though it was impossible even in a low shear rate plateplate rheometer.

미세구조 해석을 통한 고농축 복합화약 시뮬란트의 유변물성 예측

고분자 결합제로 vinyl acetate(VA) 함량이 각각 30, 60%인 poly(ethylene-co-vinyl acetate)(EVA)를 사용하여 고농축 복합화약 시뮬란트의 유변학적 특성을 연구하였다. 충전제로는 탄산칼슘 및 research department explosive (RDX)와 물리적 특성이 유사한 Dechlorane을 사용하였다. 회분식 용융 혼련기를 사용하여 농축 현탁계를 혼련하였는데 최대 75 v%까지 충전이 가능하였다. 동적 기계적 물성 변화를 측정한 결과 Dechlorane이 탄산칼슘보다 결합제수지와 더 높은 상호작용을 보였다. 일정 전단속도 방식과 일정 전단응력 방식의 평판-평판 레오미터를 사용하여 현탁계의 미세구조의 변화가 유변물성에 미치는 영향을 조사하였고, Krieger-Dougherty 식을 사용하여 최대 충전 부피분율 및 고유점도를 구하였다. EVA31/Dechlorane 현탁계의 최대 충전 부피분율은 약 70 v%이고, 혼련시 전단응력이 약 2000 Pa 정도 부가되는 것이 적절함을 알 수 있었다. The rheological properties of highly concentrated polymer bonded explosive simulant were studied by using poly(ethylene-co-vinyl acetate) with 30 and 60% vinyl acetate (VA) content as a binder, respectively. Calcium carbonate and Dechlorane, whose physical properties are similar to resarch department explosive (RDX)'s, were used as fillers. The suspensions were mixed in a batch melt mixer and it was possible to fill 75 v% at maximum. From dynamic mechanical analysis, Dechlorane showed higher interaction with binder resins than that with calcium carbonate fillers. The effects of microstructural change on the rheological properties of the suspensions were investigated by a plate-plate rheometer with constant shear rate and constant shear stress modes, respectively. The theoretical maximum packing fraction of EVA31/Dechlorane suspension obtained from Krieger-Dougherty equation was 70 v% and it was thought that 2000 Pa was proper shear stress condition for this melt processing.

고농축 복합화약 시뮬란트의 유변학적 특성: 벽면 미끄러짐, 틱소트로피, 유동불안정성

고분자 결합제로 hydroxyl terminated polybutadiene(HTPB)와 폴리에틸렌 플라스토머인 Exact를 사용한 고농축 복합화약 시뮬란트의 유변학적 특성을 연구하였다. 충전제로서 설탕 및 research department explosive(RDX)와 물리적 특성이 유사한 Dechlorane을 사용하였다. HTPB 사용시에는 가소제로 diethyl hexyl adipate(DEHA or DOA)를 첨가하기도 하였다. 농축 현탁계의 혼화는 시그마 블레이드가 장착된 회분식 혼련기(Rheomix 600, Haake) 를 사용하였고 유변학적 물성은 평판-평판 레오미터 및 모세관 레오미터를 이용하였다. 고농축 결합제/충전제 현탁계의 벽면 미끄러짐 현상, 전단 히스테리시스에 따른 틱소트로피 거동, 전단속도 및 충전제 첨가에 따른 유동불안정성 변화를 조사하였다. The rheological characteristics of highly concentrated polymer bonded explosive simulant were studied. Hydroxyl terminated polybutadiene (HTPB) and polyethylene plastomer (Exact) were used as binders. Sugar and Dechlorane particles whose physical properties are similar to research department explosive (RDX) were used as fillers. When HTPB was used, diethyl hexyl adipate (DEHA or DOA) was used as a plasticizer together for some cases. Highly concentrated suspensions were mixed in a batch melt mixer (Rheomixer 600, Haake) and rheological properties were measured by plate-plate and capillary rheometers. Wall slip phenomena, thixotropy with shear hysteresis, and flow instability were investigated as shear rate and amount of fillers changed.

Preparation and Characteristics of Rat Anti-1,3,5-Trinitroperhydro-1,3,5-Triazine (RDX) Monoclonal Antibody and Detection of RDX Using Surface Plasmon Resonance Immunosensor

In this paper, we develop a method of detecting 1,3,5-trinitroperhydro-1,3,5-triazine [research department explosive (RDX)]. RDX is one of the main components of plastic explosives. Initially, we prepare an anti-RDX monoclonal antibody that specifically binds to RDX. The antibody is prepared from hybridoma cells that are prepared by the iliac lymph node method. The dissociation constant of the antibody against RDX is estimated to be 9.6 nM from the results of indirect competitive enzyme-linked immunosorbent assay. We fabricate a sensor chip on which RDX analogues are immobilized through a self-assembled monolayer with oligo(ethylene glycol) chains. High reliability and low false recognition rate are particularly required for sensors used for detecting explosives. Therefore, the nonspecific adsorption of the fabricated sensor chip is evaluated to confirm whether the sensor chip inhibits this nonspecific adsorption. The response characteristics of the prepared antibody against RDX are examined by indirect competitive assay. Under an incubation time of 0 min in the indirect competitive assay, a detection limit of 40 ppt is realized at a sample injection duration of 6 min.

Silver nano-entities through ultrafast double ablation in aqueous media for surface enhanced Raman scattering and photonics applications

We have fabricated stable silver nanoparticles (NPs) and nanostructures (NSs) effectively through double ablation of bulk silver substrate immersed in double distilled water using ∼2 ps laser pulses. The effects of multiple/double/single ablation on silver substrates via surface morphology studies along with average size distribution of Ag NPs were investigated. Prepared Ag NPs in solution exhibited yellow color with an absorption peak near 410 nm, assigned to localized surface Plasmon resonance of nano-sized silver. Depending on the ablation parameters average sizes observed were ∼13 nm/∼17 nm in multiple/double ablation case and ∼7 nm in single ablation case. High resolution transmission electron microscope studies highlighted that most of the Ag NPs were spherical and polycrystalline in nature. Surface morphology of the substrates was characterized by field emission scanning electron microscope and atomic force microscope. A different scenario was observed in the double ablation case compared to single/multiple ablation case. Double ablation resulted in dome like NSs on the substrate with dimensions of few hundreds of nanometers while single ablation did not. Nonlinear optical (NLO) properties of Ag NPs were investigated using Z-scan technique with ∼2 ps pulses and corresponding NLO coefficients were obtained. Surface enhanced Raman scattering (SERS) studies on multiple/double ablated Ag substrates with adsorbed Rhodamine 6G molecules were carried out using excitation wavelengths of 532 nm, 785 nm, and three orders of enhancement in Raman signal intensity was observed. Furthermore, influence of laser fluence on the fabrication of SERS active Ag substrates with double ablation was also investigated. In this case, Raman spectra of adsorbed Research Department eXplosive (RDX) molecules on ablated surfaces were recorded for 532 nm and 785 nm excitation. Enhancements up to 460 were observed from substrates fabricated at fluences of 12 J/cm2, 16 J/cm2 with excitation wavelengths of 532 nm and 785 nm, respectively.

Computational Studies on Nitro Derivatives of 1-Hydroxy-1,2,4-triazole

Thermodynamic properties and energetics of the nitro derivatives of 1-hydroxy-1,2,4-triazole, viz. 1-hydroxy-3-nitro-1,2,4-triazole (A), 1-hydroxy-5-nitro-1,2,4-triazole (B), and 1-hydroxy-3,5-dinitro-1,2,4-triazole (C), are considered for a detailed computational study during the present investigation using a density functional theory B3LYP/6-311G(d,p) method as implemented in the Gaussian 03 suite of programs. Heats of formation and other thermodynamic properties for all of the compounds considered were determined. Studies revealed that these compounds possess the requisite properties for use as high-density energetic materials. Detonation velocity (D) and detonation pressure (P) of the title compounds were evaluated using the Kamlet-Jacobs method based on the crystal densities calculated at the DFT(B3LYP)/6-311G(d,p) level incorporating the electrostatic interaction. Calculation showed that these compounds yielded a detonation pressure and detonation velocity in the range of 27–35 GPa and ∼8 km/s, respectively, at loading densities of 1.60–1.90 g/cm3. The calculated values are comparable to the values determined for powerful commercial explosives such as Research Department Explosive (RDX) (34.10 GPa, 8.75 km/s, 1.80 g/cm3), High Melting Explosive (HMX) (39.00 GPa, 9.11 km/s, 1.89 g/cm3), and Trinitrotoluene (TNT) (21.00 GPa, 6.93 km/s, 1.64 g/cm3).

Prevention of nonspecific adsorption onto a poly(dimethylsiloxane) microchannel in a microsensor chip by using a self-assembled monolayer

Poly (dimethylsiloxane) (PDMS) is meant to be utilized for a miniaturized sensor system. However, protein and biospecies often adsorb onto a PDMS surface nonspecifically. This matter is a serious challenge in the study of miniaturized sensor systems. We provide the solution, which is a prevention technique of nonspecific adsorption onto a PDMS microchip by using a functionalized silane compound self-assembled monolayer. Two demonstrations for bacteria and explosives were examined by atomic force microscopy and x-ray photoelectron spectroscopy. It was found that 1H, 1H, 2H, 2H-Perfluorooctyltriethoxysilane self-assembled monolayer on PDMS effectively blocked the nonspecific adsorption of Escherichia coli (O157:H7) and explosives such as 2, 4, 6-trinitrotoluene and 1, 3, 5-trinitroperhydro-1,3,5-triazine (RDX, Research Department Explosive).

Voltammetric determination of nitroaromatic and nitramine explosives contamination in soil

The contamination of soil by nitroaromatic and nitramine explosives is widespread during the manufacture, testing and disposal of explosives and ammunitions. The analysis for the presence of trace explosive contaminants in soil becomes important in the light of their effect on the growth of different varieties of plants and crops. 2,4,6-Trinitrotoluene (TNT), cyclotrimethylene trinitramine (Research Department explosive, RDX) and cyclotetramethylene tetranitramine (high melting point explosive, HMX), other related explosive compounds and their by-products must be monitored in soil and surrounding waterways since these are mutagenic, toxic and persistent pollutants that can leach from the contaminated soil to accumulate in the food chain. In this study, a voltammetric method has been developed for the determination of explosive such as RDX, HMX and TNT. The electrochemical redox behavior of RDX, HMX and TNT was studied through cyclic voltammetry and quantitative determination was carried out by using square wave voltammetry technique. Calibration curves were drawn and were linear in the range of 63–129 ppm for RDX with a detection limit of 10 ppm, 49–182 ppm for HMX with a detection limit of 1 ppm and 38–139 ppm for TNT with a detection limit of 1 ppm. This method was applied to determine the contaminations in several soil samples that yielded a relative error of 1% in the concentrations.