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A new and efficient catalytic hydrolysis of aliphatic and aromatic thiolates under ambient conditions is presented. Previously, we have demonstrated (Ganguly et al.

Flavodiiron nitric oxide reductases (FNORs) protect microbes from nitrosative stress under anaerobic conditions by mediating the reduction of nitric oxide (NO) to nitrous oxide (N2O). The proposed mechanism for the catalytic reduction of NO by FNORs involves a dinitrosyldiiron intermediate with a [hs-{FeNO}7]2 formulation, which produces N2O and a diferric species. Moreover, both NO and hydrogen sulfide (H2S) have been implicated in several similar physiological functions in biology and are also known to cross paths in cell signaling. Here we report the synthesis, spectroscopic and theoretical characterization, and N2O production activity of an unprecedented monohydrosulfidodinitrosyldiiron compound, with a [(HS)hs-{FeNO}7/hs-{FeNO}7] formulation, that models the key dinitrosyl intermediate of FNORs. The generation of N2O from this unique compound follows a semireduced pathway, where one-electron reduction generates a reactive hs-{FeNO}8 center via the occupation of an Fe-NO antibonding orbital. In contrast to the well-known reactivity of H2S and NO, the coordinated hydrosulfide remains unreactive toward NO and acts only as a spectator ligand during the NO reduction process.

A detailed study for the synthesis of dinickel(II)-thiolate and dinickel(II)-hydrosulfide complexes and the complete characterization of the relevant intermediates involved in the C-S bond cleavage of thiolates are presented. Hydrated Ni(II) salts mediate the hydrolytic C-S bond cleavage of thiolates (NaSR/RSH; R = Me, Et, nBu, tBu), albeit inefficiently, to yield a mixture of a dinickel(II)-hydrosulfide complex, [Ni2(BPMP)(μ-SH)(DMF)2]2+ (1), and the corresponding dinickel(II)-thiolate complexes, such as [Ni2(BPMP)(μ-SEt)(ClO4)]1+ (2) (HBPMP is 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol). A systematic study for the reactivity of thiolates with Ni(II) was therefore pursued which finally yielded 1 as a pure product which has been characterized in comparison with the dinickel(II)-dichloride complex, [Ni2(BPMP)(Cl)2(MeOH)2]1+ (3). While the reaction of thiolates with anhydrous Ni(OTf)2 in dry conditions could only yield [Ni2(BPMP)(OTf)2]1+ (5) instead of the expected dinickel(II)-thiolate compound, the C-S bond cleavage could be suppressed by the use of a chelating thiol, such as PhCOSH, to yield [Ni2(BPMP)(SCOPh)2]1+ (6). Finally, with the suitable choice of a monodentate thiol, a dinickel(II)-monothiolate complex, [Ni2(BPMP)(SPh)(DMF)(MeOH)(H2O)]2+ (7), was isolated as a pure product within 1 h of reaction, which after a longer time of reaction yielded 1 and PhOH. Complex 7 may thus be regarded as the intermediate that precedes the C-S bond cleavage and is generated by the reaction of a thiolate with an initially formed dinickel(II)-solvento complex, [Ni2(BPMP)(MeOH)2(H2O)2]3+(4). Selected dinickel(II) complexes were explored further for the scope of substitution reactions, and the results include the isolation of a dinickel(II)-bis(thiolate) complex, [Ni2(BPMP)(μ-SPh)2]1+ (8).

The synthesis and characterization of a series of new binuclear Zn(II) complexes bearing (i) terminal H2O/OH, (ii) bridging thiolates, (iii) bridging thiocarboxylates, (iv) bridging carboxylates, and (v) bridging carboxylate bearing free thiol groups are presented. Unlike the previously reported Co(II) and Fe(II) mediated desulfurization of thiolates to yield binuclear Co(II)/Fe(II)-hydrosulfide complexes by us (Jana et al., Inorg. Chem., 2018, 57, 617; Pal et al., Dalton Trans., 2019, 48, 5903), Zn(II) was found to be incapable of mediating the C–S bond cleavage of thiolates and thus allowed the isolation of binuclear Zn(II)–thiolate complexes. These binuclear Zn(II)–thiolate complexes were further examined for chemical oxidation of the coordinated thiolates and insertion of neutral sulfur into the Zn(II)–thiolate bonds. Interestingly, the latter reactivity study demonstrated the formation of a new binuclear Zn(II) complex featuring a bridging S32− unit which was generated via a redox reaction involving the bridging thiolates and the externally added elemental sulfur.

Reduction of nitric oxide (NO) to nitrous oxide (N2O) is associated with immense biological and health implications. Flavodiiron nitric oxide reductases (FNORs) are diiron containing enzymes that catalyze the two electron reduction of NO to N2O and help certain pathogenic bacteria to survive under “nitrosative stress” in anaerobic growth conditions. Consequently, invading bacteria can proliferate inside the body of mammals by bypassing the immune defense mechanism involving NO and may thus lead to harmful infections. Various mechanisms, namely the direct reduction, semireduction, superreduction and hyponitrite mechanisms, have been proposed over time for catalytic NO reduction by FNORs. Model studies in relation to the diiron active site of FNORs have immensely helped to replicate the minimal structure–reactivity relationship and to understand the mechanism of NO reduction. A brief overview of the FNOR activity and the proposed reaction mechanisms followed by a systematic description and detailed analysis of the model studies is presented, which describes the development in the area of NO reduction by diiron complexes and its implications. A great deal of successful modeling chemistry as well as the shortcomings related to the synthesis and reactivity studies is discussed in detail. Finally, future prospects in this particular area of research are proposed, which in due course may bring more clarity in the understanding of this important redox reaction.

A unique Co(II)- and Fe(II)-mediated complete desulfurization of disulfides of the type RS-SR and RC(O)S-SC(O)R to yield the corresponding alcohols (ROH) and carboxylic acids (RCOOH), respectively, along with the formation of a dicobalt(II)/diiron(II)-hydrosulfide complex, [M

The synthesis and a detailed reactivity study of a binuclear zinc(II) bis(benzenethiolate) complex, [Zn

Flavodiiron nitric oxide reductases (FNORs) protect microbes from nitrosative stress under anaerobic conditions by mediating the reduction of nitric oxide (NO) to nitrous oxide (N

This article outlines a set of plug-in tools running on MATLAB to automatically import, preprocess, and evaluate the quality of electro-encephalography (EEG) data stored using the Brain Imaging Data Structure BIDS-EEG standard. As a proof of concept, we apply several possible data quality metrics to 30 EEG studies (sets of compatible datasets) currently available in BIDS-EEG format on the OpenNeuro.org platform. The bids-matlab-tools plug-in for EEGLAB (sccn.ucsd.edu/EEGLAB) checks for the presence of information needed for analysis, then applies preprocessing pipelines that compute data quality metrics and retain dataset portions (e.g., those channels and time points) that appear suitable for analysis. These and other data measures and visualizations will be made available to the EEG community through a new NEMAR.org web portal now under development to support the use of the OpenNeuro.org data archive by the human electrophysiology research community.

While the attempted synthesis of diiron(ii)-hydrosulfide complexes using HS- produced an insoluble precipitate, the reaction of Fe(BF4)2·6H2O, Et3N and HN-Et-HPTB with RSH (R = tBu, CH2Ph) yielded the desired complex, [Fe2(N-Et-HPTB)(SH)(H2O)](BF4)2 (1a). The synthesis, one electron oxidation and dioxygen activity of 1a in comparison with an analogous chloride complex, [Fe2(N-Et-HPTB)(Cl)(DMF)2](BF4)2 (2), are described.

The reduction of NO to N2O by flavodiiron nitric oxide reductases (FNORs) is related to the disruption of the defense mechanism in mammals against invading pathogens. The proposed mechanism for this catalytic reaction involves both nonheme mono- and dinitrosyl diiron(II) species as the key intermediates. Recently, we reported an initial account for NO reduction activity of an unprecedented mononitrosyl diiron(II) complex, [Fe2(N-Et-HPTB)(NO)(DMF)3](BF4)3 (1) (N-Et-HPTB is the anion of N,N,N',N'-tetrakis(2-(l-ethylbenzimidazolyl))-2-hydroxy-1,3-diaminopropane; DMF = dimethylformamide) with [FeII{FeNO}7] formulation [Jana et al. J. Am. Chem. Soc. 2017, 139, 14380]. Here we report the full account for the selective synthesis, characterization, and reactivity of FNOR model complexes, which include a dinitrosyl diiron(II) complex, [Fe2(N-Et-HPTB)(NO)2(DMF)2](BF4)3 (2) with [{FeNO}7]2 formulation and a related, mixed-valent diiron(II, III) complex, [Fe2(N-Et-HPTB)(OH)(DMF)3](BF4)3 (3). Importantly, whereas complex 2 is able to produce 89% of N2O via a semireduced mechanism (1 equiv of CoCp2 per dimer = 50% of NO reduced), complex 1, under the same conditions (0.5 equiv of CoCp2 per dimer = 50% of NO reduced), generates only ∼50% of N2O. The mononitrosyl complex therefore requires superreduction for quantitative N2O generation, which constitutes an interesting dichotomy between 1 and 2. Reaction products obtained after N2O generation by 2 using 1 and 2 equiv of reductant were characterized by molecular structure determination and electron paramagnetic resonance spectroscopy. Despite several available literature reports on N2O generation by diiron complexes, this is the first case where the end products from these reactions could be characterized unambiguously, which clarifies a number of tantalizing observations about the nature of these products in the literature.

Desulfurization of organosulfur compounds is a highly important reaction because of its relevance to the hydrodesulfurization (HDS) process of fossil fuels. A reaction system involving Co(BF4)2·6H2O and the dinucleating ligands HBPMP or HPhBIMP has been developed that could desulfurize a large number of thiophenes, sulfides, and thiols to generate the complexes [Co2(BPMP)(μ2-SH)(MeCN)](BF4)2 (1a), [Co2(BPMP)(SH)2](BF4) (1b), and [Co2(PhBIMP)(μ2-SH)(X)](BF4)2 [X = DMF (2a), MeCN (2c)], while the substrates are mostly converted to the corresponding alcohols/phenols. This convenient desulfurization process has been demonstrated for 25 substrates in 6 different solvents at room temperature.

A reaction system involving Fe(BF4)2·6H2O and two dinucleating ligands, HBPMP and HPhBIMP, mediates the desulfurization of aliphatic and aromatic thiols at room temperature. This rare C-S bond cleavage reaction produces two nonheme diiron(II) complexes, [Fe2(BPMP)(SH)2(MeOH)2]1+ (1a) and [Fe2(PhBIMP)(μ-SH)(DMF)]2+ (2a), possibly via an active species similar to [Fe2(PhBIMP)(H2O)2(DMF)2]3+ (2c), while the thiols are converted to the corresponding alcohols/phenols. In the case of thioacetic acid, a bidentate chelating organosulfur substrate, the use of HBPMP produces the corresponding bis-thiocarboxylato bridged complex, [Fe2(BPMP)(CH3COS)2]1+ (1b), instead of 1a. However, the use of HPhBIMP allows the Fe(II) mediated desulfurization of thioacetic acid as well to yield 2a, along with the formation of [Fe2(PhBIMP)(CH3COS)(MeCN)]2+ (2b). This convenient desulfurization reaction has been demonstrated for different substrates in different solvents along with the structural and spectroscopic characterizations of the diiron(II)-hydrosulfide complexes in comparison with two isostructural chloride complexes, [Fe2(BPMP)(Cl)2(MeOH)2]1+ (1c) and [Fe2(PhBIMP)(μ-Cl)(DMF)]2+ (2d). The role of the individual reactants in the desulfurization process has been thoroughly investigated using control reactions, and on the basis of these results and the identification of intermediate species, such as [Fe2(PhBIMP)(StBu)(DMF)3]2+ and [Fe2(PhBIMP)(StBu)(H2O)(DMF)2]2+, in solution by mass spectrometry, a possible mechanism has been proposed.

There is a growing demand for low-cost and effective test solutions to support state-of-the-art analog and mixed-signal systems that are continuously increasing in complexity and functionality, while decreasing in product cost. This innovative practice session highlights various aspects of design for test (DfT) in high-complexity, analog-dominated systems with three talks that focus on: DfT in power management integrated circuits (ICs), an alternative testing method to analog test bus, and pre-silicon built-in self-test (BIST) verification, where BIST is used to monitor complex mixed-signal systems. These talks will be given by industry experts from Dialog Semiconductor, Xilinx, and Texas Instruments.

Reactions of CuCl, CuCl2 and CuBr2 with 1,3,5-tri-tert-butyl-1,3,5-triazacyclohexane (tBu3tach) resulted in the formation of [(tBu3tach-H)+(CuCl2)] (1), [(tBu3tach)(CuCl2)] (2) and [(tBu3tach-H)+(CuBr2)] (3) respectively. Interestingly, CuBr was found to mediate the cleavage of the C–N bonds of tBu3tach in a vast range of solvents, namely, chloroform, dichloromethane, tetrahydrofuran, acetonitrile and methanol to yield [Cu4Br4(tBuNCH2)4] (4) and stands as an example of C–N bond cleavage of 1,3,5-triazacyclohexane rings by copper salts. Compounds 1 and 3 contains amidinium cations and are unstable in solution towards the release of copper. The release of copper from 3 in solution was confirmed by the isolation of the compound, [CuBr(MeCN)] (5). Formation of the amidinium cations [(tBu3tach-H)+] in 1 and 3 may be avoided by the use of PPh3 to yield [(tBu3tach)Cu(PPh3)](PF6) (6), while the coordinated N-tert-butylmethanimine (tBuNCH2) in 4 could be replaced by PPh3 to yield [Cu4Br4(PPh3)4] (7). Complexes 1–7 are characterized by a combination of single crystal X-ray structure determination and/or elemental analysis, NMR, IR, and UV–Vis spectroscopy, and Mass spectrometry.

In this paper we analyze the performance of the computational neuroscience tool NEURON on Intel Knights Corner processors. Knights Corner was the many core processor that was followed by Knights Landing processors. NEURON is a widely used simulation environment for modeling individual neurons and network of neurons. NEURON is used to simulate large models requiring high performance computing, and understanding performance of NEURON on many core processors is of interest to the neuroscience community, as well as to the high performance computing community. NEURON supports parallelization using Message Passing Interface (MPI) library. Parallel performance of NEURON has been analyzed on various types of high performance resources. We analyze the performance and load balance of NEURON for two different size problems on Knights Corner. We use the TAU and Vampir tool to analyze load imbalance issues of these runs. We compare performance on the host SandyBridge processors of Knights Corner versus on the Many Integrated Core (MIC) cores of Knights Corner.

Considering the necessity to build up corporate social responsibility (CSR) activities in general and sustainability in particular under statutory obligations, Ministry of Corporate Affairs, Government of India had notified in Companies Act 2013 (section 135) that every public limited company and private limited company having net worth of more than 500 crore or turnover more than 1000 crore or net profit more than 5 crore needs to comply with CSR rules (i.e., contributing 2% or more for the welfare of society following the prescribed guidelines under Schedule VII). The chapter focuses on CSR activities of companies registered under BSE SENSEX and evaluating their current status in CSR activities from the perspective of the broad heading of planet and people. A detailed analysis is done to highlight the current situation of the companies towards sustainable development through corporate sustainability index and statistical tools like Kruskal-Wallis test and Mann-Whitney U test to represent the contributions of these companies towards the environmental responsibilities. The study of CSR reveals the endeavors of surveyed companies towards the holistic development covering the noteworthy issue of environmental protection and sustainability; however, a continuous vigil from the regulatory bodies is the need of the hour to ensure that adherence to CSR practices should not only be in mere form but in true spirits.

This work looks at analyzing I/O traffic of users’ jobs on a HPC machine for a period of time. Monitoring tools are collecting the data in a continuous basis on the HPC system. We looked at aggregate I/O data usage patterns of users’ jobs on the system both on the parallel shared Lustre file system and the node-local SSDs. Data mining tools are then applied to analyze the I/O usage pattern data in an attempt to tie the data to particular codes that produced those I/O behaviors from users’ jobs.

Synthesis and reactivity of a series of thiolate/thiocarboxylate bridged dicobalt(II) complexes were investigated in comparison with their carboxylate bridged analogues bearing free thiol/hydroxyl groups. Upon one-electron oxidation, complexes [Co2(N-Et-HPTB)(μ-SR1)](BF4)2 (R1 = Ph, 1a; Et, 1b; Py, 1c) and [Co2(N-Et-HPTB)(μ-SCOR2)](BF4)2 (R2 = Ph, 2a; Me, 2b) yielded [Co2(N-Et-HPTB)(DMF)2](BF4)3 (6) (DMF = dimethylformamide) along with the corresponding disulfides (where N-Et-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane). Unlike the inertness of carboxylate bridged complexes [Co2(N-Et-HPTB)(μ-O2C-R3-SH)](BF4)2 (R3 = Ph, 3a; CH2CH2, 3b) and [Co2(N-Et-HPTB)(μ-O2CR4)](BF4)2 (R4 = Ph, 4a; Me, 4b; CH2CH2CH2OH, 5) toward O2, the bridging ethanethiolate in 1b was oxidized to yield a sulfinate bridged complex, [Co2(N-Et-HPTB)(μ-O2SEt)](BF4)2 (10). Detailed investigation of the synthetic aspects of 1a-1c led to the discovery of a C-S bond cleavage reaction and yielded the dicobalt(II) complexes [Co2(N-Et-HPTB)(SH)(H2O)](BF4)2 (8a), [Co2(N-CH2Py-HPTB)(SH)(H2O)](BF4)2 (8b) (where N-CH2Py-HPTB is the anion of N,N,N',N'-tetrakis[2-(1-picolylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane)), and [Co2(N-Et-HPTB)(μ-S)](BF4) (9). Both 8a and 8b feature nonheme dinuclear Co(II) units containing a terminal hydrosulfide. The present study thus reports comparative redox reactions for a rare class of 16 dicobalt(II) complexes and introduces a selective synthetic strategy for the synthesis of unprecedented dicobalt(II) complexes featuring only one terminal hydrosulfide.

Reaction of [Fe

Science Gateways provide user environments and a set of supporting services that help researchers make effective and enhanced use of a diverse set of computing, storage, and related resources. Gateways provide the services and tools users require to enable their scientific exploration, which includes tasks such as running computer simulations or performing data analysis. Historically gateways have been constructed to support the workflow of individual users, but collaboration between users has become an increasingly important part of the discovery process. This trend has created a driving need for gateways to support data sharing between users. For example, a chemistry research group may want to run simulations collaboratively, analyze experimental data or tune parameter studies based on simulation output generated by peers, whether as a default capability, or through explicit creation of sharing privileges. As another example, students in a classroom setting may be required to share their simulation output or data analysis results with the instructor. However most existing gateways (including the popularly used XSEDE gateways SEAGrid, Ultrascan, CIPRES, and NSG), do not support direct data sharing, so users have to handle these collaborations outside the gateway environment. Given the importance of collaboration in current scientific practice, user collaboration should be a prime consideration in building science gateways. In this work, we present design considerations and implementation of a generic model that can be used to describe and handle a diverse set of user collaboration use cases that arise in gateways, based on general requirements gathered from the SEAGrid, CIPRES, and NSG gateways. We then describe the integration of this sharing service into these gateways. Though the model and the system were tested and used in the context of Science Gateways, the concepts are universally applicable to any domain, and the service can support data sharing in a wide variety of use cases.

The Comet petascale supercomputer was put into production as an XSEDE resource in early 2015 with the goal of serving a much larger user community than HPC systems of similar size. The Comet project set an audacious goal of reaching over 10,000 users in its four years of planned operation. That goal was achieved in less than two years, due in large part to the adoption of policies that favor smaller allocations and science gateways. Here we describe our experiences in operating and supporting Comet, highlight some of the important science that it has enabled, and provide some practical lessons that we have learned by operating a system designed for the long tail of science.

Two non-heme iron-nitrosyl species, [Fe2(N-Et-HPTB)(O2CPh)(NO)2](BF4)2 (1a) and [Fe2(N-Et-HPTB)(DMF)2(NO)(OH)](BF4)3 (2a), are characterized by FTIR and resonance Raman spectroscopy. Binding of NO is reversible in both complexes, which are prone to NO photolysis under visible light illumination. Photoproduction of N2O occurs in high yield for 1a but not 2a. Low-temperature FTIR photolysis experiments with 1a in acetonitrile do not reveal any intermediate species, but in THF at room temperature, a new {FeNO}(7) species quickly forms under illumination and exhibits a ν(NO) vibration indicative of nitroxyl-like character. This metastable species reacts further under illumination to produce N2O. A reaction mechanism is proposed, and implications for NO reduction in flavodiiron proteins are discussed.