CS Gas Research Articles

Structural analysis and theoretical studies of 2-(2-chlorobenzylidene) malononitrile (CS) “a riot controlling agent”

In solvent methanol, malononitrile and 2-chlorobenzaldehyde were stirred in the presence of base piperidine to synthesise the target chemical 2-(2-chlorobenzylidene) malononitrile (CS). The crystal structure of the target compound C10H5ClN2 has been elucidated through X-ray crystallographic analysis. It crystallises in the monoclinic crystal system within the P21 space group, containing four molecules per asymmetric unit. The unit cell dimensions are a = 3.8825(3) Å, b = 21.0202(18) Å, c = 21.3481(18) Å, and β = 95.096(4)°. The phenyl and malononitrile groups, which make up the molecular components, are each planar but slanted towards one another at a dihedral angle of 12.7° (4). Besides this, target molecule is also stabilized by hydrogen bonding, halogen bonding and π stacking interactions. Solid-state structure has been analysed through Hirshfeld surface analysis, including the evaluation of the different energy frameworks, indicating that the molecular sheets are primarily formed by hydrogen bonds and halogen bonds and the stabilization is dominated via the electrostatic energy contribution. Fingerprint plots were carried out to study the relative contribution of noncovalent interactions in the target compound CS. Further, the density functional theory calculations were employed using B3LYP hybrid functional with 6-311++G level basic set to optimize the structural coordinates in gas phase and in different solvents (chloroform, water, and methanol). The chemically active regions of the target compound were identified by the analysis of molecular electrostatic potential surface. Further, from PASS analysis and literature reports, molecular docking of title compounds was carried out with human transient receptor potential ankyrin 1 ion channel (hTRPA1) (PDB-ID 6PQO). ΔGb (docking energy) and inhibition constant was calculated to be −7.53 kcal/mol and 3.33 μM respectively, with the target ion channel.

Organocatalytic Synthesis of (Hetero)arylidene Malononitriles Using a More Sustainable, Greener, and Scalable Strategy.

The establishment of a green and sustainable Knoevenagel condensation reaction in organic chemistry is still crucial. This work aimed to provide a newly developed metal-free and halogen-free catalytic methodology for the synthesis of CS and (hetero-) arylidene malononitriles in the laboratory and industrial scale. The Knoevenagel condensation reaction of various carbonyl groups with malononitrile was investigated in ethanol, an ecofriendly medium, in the presence of seven nitrogen-based organocatalysts. A comparative study was conducted using two as-obtained and four commercially available nitrogen-based organocatalysts in Knoevenagel condensation reactions. The synthesis of CS gas (2-chlorobenzylidene malononitrile) using a closed catalytic system was optimized based on their efficiency and greener approach. The conversion of 100% and excellent yields were obtained in a short time. The products could be crystallized directly from the reaction mixture. After separating pure products, the residue solution was employed directly in the next run without any concentration, activation, purification, or separation. Furthermore, the synthesis of 2-chlorobenzylidenemahmonitrile (CS) was carried out on a large scale using imidazole as a selected nitrogen-based catalyst, afforded crystalline products with 95 ± 2% yield in five consecutive runs. Energy efficiency, cost saving, greener conditions, using only 5 mol% of organocatalyst, high recyclability of catalyst, prevention of waste, recycling extractant by a rotary evaporator for non-crystallized products, demonstrated the potential commercial production of CS using imidazole in ethanol as an efficient and highly recyclable catalytic system.

Reduction of Oxygen Production by Algal Cells in the Presence of O-Chlorobenzylidene Malononitrile.

Chemical compounds, such as the CS gas employed in military operations, have a number of characteristics that impact the ecosystem by upsetting its natural balance. In this work, the toxicity limit and microorganism's reaction to the oxidative stress induced by O-chlorobenzylidenemalonitrile, a chemical found in CS gas, were assessed in relation to the green algae Chlorella pyrenoidosa. A number of parameters, including the cell growth curve, the percent inhibition in yield, the dry cell weight, the percentage viability and productivity of algal biomass flocculation activity, and the change in oxygen production, were analyzed in order to comprehend the toxicological mechanisms of O-chlorobenzylidenemalonitrile on algal culture. Using fluorescence and Fourier transform infrared spectroscopy (FTIR), the content of chlorophyll pigments was determined. The values obtained for pH during the adaptation period of the C. pyrenoidosa culture were between 6.0 and 6.8, O2 had values between 6.5 and 7.0 mg/L, and the conductivity was 165-210 µS/cm. For the 20 µg/mL O-chlorobenzylidenemalonitrile concentration, the cell viability percentage was over 97.4%, and for the 150 µg/mL O-chlorobenzylidenemalonitrile concentration was 74%. The ECb50 value for C. pyrenoidosa was determined from the slope of the calibration curve; it was estimated by extrapolation to the value of 298.24 µg/mL. With the help of this study, basic information on the toxicity of O-chlorobenzylidenemalonitrile to aquatic creatures will be available, which will serve as a foundation for evaluating the possible effects on aquatic ecosystems. The management of the decontamination of the impacted areas could take the results into consideration.

Synthesis, Purity Check, Hydrolysis and Removal of o-Chlorobenzyliden Malononitrile (CBM) by Biological Selective Media.

The removal yield of organic substances present in water depends on the environmental conditions, on the chemical composition of the water and on the chemical substance dissolved in the water, which constitutes the substrate of the metabolic activities of the microalgae that use these substances in the biochemical reactions of cellular enzyme complexes. o-Chlorobenzylidene malononitrile (CS, to use its military designation) was synthesized in-house, for research purposes, by a condensing reaction between o-chlorobenzaldehide and malononitrilein the presence of diethylamine. The detection, identification and confirmation of o-chlorobenzylidenemalononitrile (coded CBM in this experimental study) was performed using gas chromatography-mass spectrometry (GC-MS) and the purity of CBM was 99%. The biodegradation capacity in the samples that contained the biological suspension, after 24 h and 96 h of incubation, was determined via GC-MS analysis, and no evidence of the presence of CBM or some metabolites of CBM was detected. In the parallel samples, a hydrolysis process of CBM at room temperature, without biological treatment, revealed two main metabolites, malononitrile and o-chlorobenzaldehyde, respectively. This study is focused on evaluating the biodegradation capacity of o-chlorobenzylidene malononitrile in the presence of a biological material, culture of Chlorella sp., in comparison with a classical hydrolysis process. The tests performed indicate that the suspension of Chlorella sp. consumed the entire amount of CBM and metabolites from the analyzed samples. The tests prove that the biological material can be used to decontaminate the affected areas.

Retrospective on Waco

The year 2023 marks the thirtieth anniversary of the deaths of eighty-two Branch Davidians, including their twenty-two children, and four agents with the Bureau of Alcohol, Tobacco, and Firearms (ATF) in a conflict at the Branch Davidians’ Mount Carmel Center property outside Waco, Texas. After the shootout between ATF agents and Branch Davidians on February 28, 1993, FBI agents took over and presided over a siege that lasted fifty-one days. The siege ended on April 19, 1993 with the FBI’s tank and CS gas assault on the Branch Davidians’ residence for six hours that concluded in a massive fire. In this “Retrospective on Waco,” Texas journalist Dick J. Reavis, author of The Ashes of Waco (1995), shares his observations on the conflict at Mount Carmel Center, and on the recent book, Waco: David Koresh, the Branch Davidians, and a Legacy of Rage (2023), by Jeff Guinn. Despite all the books written since 1993, no definitive account of the complex events at Mount Carmel Center has been published.

Noxious effects of riot control agents on the ocular surface: Pathogenic mechanisms and management.

Riot Control Agents (RCAs) are chemical compounds used by law enforcement agencies to quell violent demonstrations as an alternative to lethal force and as part of police/military training. They are also known as tear gases because of the hallmark ocular irritation and lacrimation they cause. The most common RCAs include oleoresin capsicum (contained in Mace and pepper spray), chlorobenzylidene malononitrile, dibenzoxazepine, and chloroacetophenone (previously the main content of Mace); some of which have been in use for decades. Their immediate incapacitating effects are mediated through polymodal afferent fibers innervating the corneal surface, inducing the release of peptides that cause neurogenic inflammation. Although previously thought to have only transient effects on exposed patients more severe complications such as corneal stromal opacities, corneal neovascularization, neurotrophic keratopathy, conjunctival necrosis, and pseudopterygium can occur. Concerningly, the lack of research and specific therapies restrict the current management to decontamination and symptom-tailored support. This manuscript will provide an overview of the toxic mechanisms of RCAs, their clinical manifestations, and current therapy after exposure to tear gases.

Enhancement of thermionic emission and conversion characteristics using polarization- and band-engineered n-type AlGaN/GaN cathodes

Enhanced thermionic emission (TE) and conversion characteristics are observed by controlling spontaneous and piezoelectric polarization and the band diagram of n-type AlGaN/GaN thermionic cathodes. Reduction in the electron affinity and work function by the insertion of an N-polarity thin n-type AlGaN (n-AlGaN) film including tensile biaxial strain is confirmed by an ultraviolet photoemission spectroscopy analysis. The obtained TE current from N-polarity n-AlGaN films grown on an n-type GaN (n-GaN) substrate is 0.29 mA at 500 °C in a Cs gas atmosphere in the vacuum gap between the cathode and a stainless steel anode. This TE current is 5.0 times and 1.6 times higher than that from the surface of Ga-polarity n-GaN substrate and that of the Ga-polarity n-AlGaN film on the substrate, respectively.

The Contamination Effects and Toxicological Characterization of o-Chlorobenzylidene Manolonitrile

Toxicological characterization and global assessment of the toxicity of some chemicals used in the specific technique of the defense and public order system (e.g. o-chlorobenzylidene manolonitrile which enters the composition of the CS gas) is especially useful for environmental protection. Based on the results obtained, the toxicological characterization (acute lethal toxicity) and the harmful potential of some toxic substances, individual or in mixture, against euythermal sweet fish are established. The tests performed aim to change the behavior of the species studied in the presence of chlorobenzylidene manolonitrile, a substance used in the technique of defense and public order system. The tests established the toxicity values of acute lethal concentration LC50 and serve to further determine the maximum allowable concentration that inhibits the development of normal fish fauna in contaminated waters. The test results allow the toxicological characterization and measurement of the acute lethal toxicity of an inhibitor, in order to make more efficient its elimination from the contaminated environment.

Observation of Cesium (nD 5/2+6S 1/2) Ultralong-Range Rydberg-Ground MoleculesSupported by the National Key R&D Program of China (Grant No. 2017YFA0304203), the National Natural Science Foundation of China (Grant Nos. 11434007, 61835007, 61675123, 61775124, and 11904215), Changjiang Scholars and Innovative Research Team in Universities of Ministry of Education of China (Grant No. IRT 17R70), and the 1331 Project.

Ultralong-range Cs2 Rydberg-ground molecules (nD 5/2 + 6S 1/2 F) (33 ≤ n ≤ 39, F = 3 or 4) are investigated by a two-photon photo-association spectroscopy of an ultracold Cs gas. Two vibrational ground molecular spectra of triplet 3 Σ and hyperfine mixed singlet-triplet 1,3 Σ molecular states and their corresponding binding energies are attained. The experimental observations are simulated by an effective Hamiltonian including low energy electron scattering pseudopotentials, the spin-orbit interaction of the Rydberg atom, and the hyperfine interaction of the ground-state atom. The zero-energy singlet and triplet s-wave scattering lengths are extracted by comparing the experimental observations and calculations. Dependences of the measured binding energies on the effective principal quantum number, n eff = n − δD (δD is the quantum defect of Rydberg D state), yield the scaling of , for deep triplet potential and , for shallow mixed singlet-triplet potential well. The simulations of low-energy Rydberg electron scattering show agreement well with the experimental measurements.

Perceptions of police use of force: the importance of trust

PurposeThe range of tactical force options available to police is increasing, while public debate about police use of force is never far from the headlines. This paper aims to examine what factors shape how people accept police use of force.Design/methodology/approachThe authors use two online experiments to test whether different force options affected judgments about the acceptability of police action and to explore the role of trust and legitimacy in people's judgments.FindingsThe authors found across both studies that respondents judged scenarios involving a weapon (baton, CS spray, Taser) as less acceptable compared to scenarios that did not (talking down, handcuffs), but they did not draw much distinction between the specific weapon used. In study 1, exposure to different police tactics had no effect on trust and legitimacy. In study 2, prior perceptions of trust were strong predictors of acceptability judgments.Originality/valueThere is a comparative paucity of British-based empirical research examining public attitudes toward different use of force resolutions by police. In this paper, the authors explore how use of force affects people's views of police at a time in which the nature and scope of force applications, how these are understood and indeed the basic enterprise of policing itself is being reconsidered and renegotiated.

Adsorption kinetic modeling of toxic vapors on activated carbon in the batch reactor

The compound ortho-chlorobenzylidene malononitrile (OCM) is the defining component of tear gas commonly referred to as CS gas. In present work, at first, OCM was changed from solid state to aerosol form (vapor) using thermal technique and then the kinetics of adsorption of OCM aerosol on a cylindrical activated carbon was experimentally investigated. For this purpose, an experimental setup was designed and manufactured for measurement of adsorbed-gas equilibrium pressure. The effects of the initial weight of OCM (3–15 mg) and time of adsorption were studied. The kinetic adsorption data were correlated with eight different models in order to select the best model for this system. The kinetic adsorption data were well described by fractal-like pseudo-first order (FL-PFO) with high correlation coefficient (average R2 > 0.9963) and the appropriate physical interpretation of model coefficients. In addition, the t test results confirm the high capability of FL-PFO model for the analysis of the kinetic data. The obtained results showed that the equilibrium adsorption time significantly increased and the adsorption rate coefficient decreased (to a minimum value) with increasing initial weight of OCM. Also, the analysis of adsorption data for this system confirms that there are heterogeneous sites in the adsorbent surface with different adsorption energies.

Airway Obstruction and Patchy Parenchymal Infiltrations Related to Tear Gas Exposure

A 50 year old nonsmoker female patient with respiratory complaints including phlegm and effort-related dyspnea admitted to the hospital. Anamnesis pointed out neither occupational nor hobby-related exposures. However, she mentioned several intense tear gas exposures, and describe dyspnea and wheezing right after these exposures. Computed tomography of the lung showed patchy areas of consolidation and ground glass opacity. Pulmonary function tests revealed an FEV1/FVC ratio of 67%. Chlorobenzylidene malononitrile (CS) gas related pulmonary involvement was evident due to the lack of lesions on previous radiographs, improvement of her complaints and respiratory function test, and regression of the parenchymal lesions after ceasing the exposure. This case is presented to emphasize the importance of taking detailed anamnesis of the patient and to demonstrate the negative impacts of physical and social environment on human health, and more specifically to suggest that the riot control gases used are not as harmless as believed.

Police use of force during street protests: A pressing public mental health concern.

Street protests are a common means of civic expression and occur across the globe. In the past few years, millions of citizens have attended street protests worldwide. Sometimes however, street protests can constitute significantly stressful and violent contexts. Research has highlighted the physical health impact of street protests due to clashes between protesters and law enforcement or use of CS gas [[1]Dimitroglou Y. Rachiotis G. Hadjichristodoulou C Exposure to the riot control agent CS and potential health effects: a systematic review of the evidence.Int J Environ Res Public Health. 2015; 12: 1397-1411Crossref PubMed Scopus (16) Google Scholar]. In addition, police use of less-lethal weapons, such as rubber pellet launchers, is known to cause severe ocular injuries [[2]Chauvin A. Bourges J.L. Korobelnik J.F Ocular injuries caused by less-lethal weapons in France.Lancet. 2019; 394: 1616-1617Summary Full Text Full Text PDF PubMed Scopus (6) Google Scholar]. Besides these physical health effects, research has recently shifted focus on the mental health aspects of streets protests. For instance, the 2019 Hong-Kong anti-extradition bill protests is responsible for increased probable depression and suspected PTSD prevalence rates among the Hong-Kong population [[3]Ni M.Y. Yao X.I. Leung K.S.M. et al.Depression and post-traumatic stress during major social unrest in Hong Kong: a 10-year prospective cohort study.Lancet. 2020; https://doi.org/10.1016/S0140-6736(19)33160-5Summary Full Text Full Text PDF Scopus (76) Google Scholar]. These mental health consequences were attributed to the stressful context of mass street protests as they happened in Hong-Kong (e.g. lootings). Yet, increased use of force by Hong Kong law enforcement in 2019 (e.g. 16,000 rounds of teargas fired vs. 87 in the Occupy Central protests of 2014 [[4]2,393 students arrested since June; 16,000 rounds of tear gas fired 2019. Available from: https://www.thestandard.com.hk/breaking-news/section/3/138217/2,393-students-arrested-since-June;-16,000-rounds-of-tear-gas-fired [Accessed 23rd January 2020].Google Scholar]), could partly explain the rise in probable PTSD and depression cases. Besides physical health consequences, the traumatic nature of police use of force may have lasting mental health consequences on citizens. Thus, police use of force may constitute a risk factor for public mental health, but the issue remains under-researched. In a recent study conducted among 523 Yellow Vests protesters in France, we assessed self-reported exposure to police violence-related traumas (yes/no items; physical abuse, rubber pellet ammunitions), to other protest-related traumas (e.g. physical injury, custody) as well as post-traumatic stress and depression symptoms [[5]Celebi E. Adam-Troian J. Mahfud Y. Positive links between exposure to police violence, PTSD, and depression symptoms among yellow vests protesters in France.J Interpers Violence. 2020; (Advance Online Publication)PubMed Google Scholar]. Across analyses and despite adjustment on a range of potential confounds (demographics, political orientation, custody and hospitalization) a systematic negative association between exposure to police violence and mental health symptoms was observed. More specifically, compared to non-exposed protesters, those exposed to at least one form of police violence were 1.54 times more likely to suffer from severe depressive symptoms and 2.58 more likely to meet the criteria for a tentative PTSD diagnosis. Therefore, we argue that police use of force during street protests may have mental health consequences for exposed individuals. Epidemiological investigations should be conducted using longitudinal designs to assess whether police use of force is a risk factor for population mental health. Given the prevalence of police use of force during street protests, there could be important implications for public mental health. All authors designed the study and revised the manuscript. JAT and YM collected the data. JAT and EC analysed the data. JAT drafted the manuscript. None. Ethic approval was obtained from Sehir University ethics board (n°29–2019).

Determination of the Purity of o-Chlorobenzylidene Malononitrile by Multiple Analysis Methods

Determination of the Purity of o-Chlorobenzylidene Malononitrile by Multiple Analysis Methods

Exocomets: A spectroscopic survey

Context.While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) aroundβPic in the early 1980s, only ∼20 stars have been reported to host exocomet-like events.Aims.We aim to expand the sample of known exocomet-host stars, as well as to monitor the hot-gas environment around stars with previously known exocometary activity.Methods.We have obtained high-resolution optical spectra of a heterogeneous sample of 117 main-sequence stars in the spectral type range from B8 to G8. The data were collected in 14 observing campaigns over the course of two years from both hemispheres. We analysed the Ca IIK&H and Na ID lines in order to search for non-photospheric absorptions that originated in the circumstellar environment and for variable events that could be caused by the outgassing of exocomet-like bodies.Results.We detected non-photospheric absorptions towards 50% of the sample, thus attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas was detected in the metallic lines inspected via narrow stable absorptions and/or variable blue- and red-shifted absorption events. Such variable events were found in 18 stars in the Ca IIand/or Na Ilines; six of them are reported in the context of this work for the first time. In some cases, the variations we report in the Ca IIK line are similar to those observed inβPic. While we do not find a significant trend in the age or location of the stars, we do find that the probability of finding CS gas in stars with largervsiniis higher. We also find a weak trend with the presence of near-infrared excess and with anomalous (λBoo-like) abundances, but this would require confirmation by expanding the sample.

Health risks of exposure to CS gas (tear gas): an update for healthcare practitioners in Hong Kong.

Health risks of exposure to CS gas (tear gas): an update for healthcare practitioners in Hong Kong.

Effect of coherent population trapping in a compact microfabricated Cs gas cell pumped by intra-cavity contacted VCSELs with rhomboidal oxide current aperture

Miniature laser source based on intracavity-contacted vertical-cavity surface-emitting laser with rhomboidal oxide current aperture was investigated for coherent population trapping (CPT) resonance excitation in microfabricated 133Cs gas cell filled with Ne buffer gas under the pressure of 300 torr. The cell operation temperature was 90°C. The laser output power was 550 μW at bias current of 3.2 mA and 65°C. The short-term stability of ∼2.5·10-11 at the measurement time of 1 sec was estimated from CPT resonance signal measurements.

Extensive Exposure to Tear Gases in Ankara.

The most common chemical substances used as mass control agents are chloroacetophenone, chlorobenzylidene malononitrile, and oleoresin capsicum. These agents not only have local and rapid effects but also have systemic and long-term effects. The aim of the present study was to discuss the patterns of tear gas exposure and to investigate its effects on respiratory functions. A face-to-face survey was conducted in 86 individuals who had been exposed to tear gas indoor and outdoor during the public protests in June 2013. The most frequently reported respiratory complaints included cough, dyspnea, phlegm, and chest pain. Spirometry measurements including forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were also performed. Indoor exposers have lower mean % predicted FVC and FEV1 values than outdoor exposers. All complaints and signs were more common in indoor exposure to tear gas than in outdoor exposure. Safety of the chemicals used as mass control agents during protests is doubtful as these agents are associated with several health risks.

Latent turn-on fluorescent probe for the detection of toxic malononitrile in water and its practical applications

A latent turn-on fluorescent probe for the detection of malononitrile (NCCH2CN), a precursor of hydrogen cyanide (HCN) in the mammalian tissue metabolism, is developed based on reaction-based fluorophore generation for the first time. Malononitrile is utilized within a wide spectrum of academic and industrial applications, and it is a key reagent to make o-chlorobenzylidene malononitrile (CS gas; tear gas), which is used for riot control. Due to its extensive use as well as potential health risks and the environmental pollution, malononitrile monitoring method has been required. In this paper, we discovered that our key sensing platform, 6-(dimethylamino)-3-hydroxy-2-naphthaldehyde (named Mal-P1), responds sensitively and selectively towards malononitrile. The Knoevenagel condensation induced benzo [g]coumarin formation of Mal-P1 with malononitrile showed significant fluorescence turn-on response. In addition, Mal-P1 showed the malononitrile sensing ability in environmental samples (real water, CS gas) and imaging ability in biological sample (HeLa cell line) using fluorescence microscopy with low cytotoxicity. The successful demonstrations will facilitate further applications in a variety of fields.

An all-sapphire Cs gas cell for a chip-scale atomic clock

We realized a Cs gas cell for a chip-scale atomic clock fabricated from single-crystal sapphire chips, which have extremely-low gas penetration coefficients. The coherent population trapping (CPT) resonance spectrum was evaluated to validate the developed sapphire Cs gas cell. A CPT resonance with a contrast of 1.5%, a frequency shift (from the Cs hyperfine transition frequency) of 55.9 kHz, and a full width at half maximum of 2.2 kHz was obtained at an incident light intensity of 40 μW cm−2. The frequency shift was mainly caused by the collision between Ne sealed in the gas cell and Cs atoms. From the experimental results, the pressure of Ne was estimated to be 10.7 kPa.