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Green hydrogen produced by water splitting using renewable electricity is essential to achieve net-zero carbon emissions. Present water electrolysis technologies are uncompetitive with low-cost grey hydrogen produced from fossil fuels, limiting their scale-up potential. Disruptive processes that decouple the hydrogen and oxygen evolution reactions and produce them in separate cells or different stages emerge as a prospective route to reduce system cost by enabling operation without expensive membranes and sealing components. Some of these processes divide the hydrogen or oxygen evolution reactions into electrochemical and chemical sub-reactions, enabling them to achieve high efficiency. However, high efficiency has been demonstrated only in a batch process with thermal swings that present operational challenges. This work introduces a breakthrough process that produces hydrogen and oxygen in separate cells and supports continuous operation in a membraneless system. We demonstrate high faradaic and electrolytic efficiency and high rate operation in a near-neutral electrolyte of NaBr in water, whereby bromide is electro-oxidized to bromate concurrent with hydrogen evolution in one cell, and bromate is chemically reduced to bromide in a catalytic reaction that evolves oxygen in another cell. This process may lead the way to high-efficiency membraneless water electrolysis that overcomes the limitations of century-old membrane electrolysis.
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Functional Protein Engineering became the hallmark in biomolecule manipulation in the new millennium, building on and surpassing the underlying structural DNA manipulation and recombination techniques developed and employed in the last decades of 20th century. Because of their prominence in almost all biological processes, proteins represent extremely important targets for engineering enhanced or altered properties that can lead to improvements exploitable in healthcare, medicine, research, biotechnology, and industry. Synthetic protein structures and functions can now be designed on a computer and/or evolved using molecular display or directed evolution methods in the laboratory. This review will focus on the recent trends in protein engineering and the impact of this technology on recent progress in science, cancer- and immunotherapies, with the emphasis on the current achievements in basic protein research using synthetic antibody (sABs) produced by phage display pipeline in the Kossiakoff laboratory at the University of Chicago (KossLab). Finally, engineering of the highly specific binding modules, such as variants of Streptococcal protein G with ultra-high orthogonal affinity for natural and engineered antibody scaffolds, and their possible applications as a plug-and-play platform for research and immunotherapy will be described.
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Bacteriófagos , Pesquisa Biomédica , Anticorpos , Bacteriófagos/genética , Biotecnologia/métodos , Biblioteca de Peptídeos , Engenharia de Proteínas/métodos , ProteínasRESUMO
Polyglutamine (polyQ) diseases are characterized by an expansion of cytosine-adenine-guanine (CAG) trinucleotide repeats encoding for an uninterrupted prolonged polyQ tract. We previously identified TRMT2A as a strong modifier of polyQ-induced toxicity in an unbiased large-scale screen in Drosophila melanogaster. This work aimed at identifying and validating pharmacological TRMT2A inhibitors as treatment opportunities for polyQ diseases in humans. Computer-aided drug discovery was implemented to identify human TRMT2A inhibitors. Additionally, the crystal structure of one protein domain, the RNA recognition motif (RRM), was determined, and Biacore experiments with the RRM were performed. The identified molecules were validated for their potency to reduce polyQ aggregation and polyQ-induced cell death in human HEK293T cells and patient derived fibroblasts. Our work provides a first step towards pharmacological inhibition of this enzyme and indicates TRMT2A as a viable drug target for polyQ diseases.
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Roquin and Regnase-1 proteins bind and post-transcriptionally regulate proinflammatory target messenger RNAs to maintain immune homeostasis. Either the sanroque mutation in Roquin-1 or loss of Regnase-1 cause systemic lupus erythematosus-like phenotypes. Analyzing mice with T cells that lack expression of Roquin-1, its paralog Roquin-2 and Regnase-1 proteins, we detect overlapping or unique phenotypes by comparing individual and combined inactivation. These comprised spontaneous activation, metabolic reprogramming and persistence of T cells leading to autoimmunity. Here, we define an interaction surface in Roquin-1 for binding to Regnase-1 that included the sanroque residue. Mutations in Roquin-1 impairing this interaction and cooperative regulation of targets induced T follicular helper cells, germinal center B cells and autoantibody formation. These mutations also improved the functionality of tumor-specific T cells by promoting their accumulation in the tumor and reducing expression of exhaustion markers. Our data reveal the physical interaction of Roquin-1 with Regnase-1 as a hub to control self-reactivity and effector functions in immune cell therapies.
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Autoimunidade , Citotoxicidade Imunológica , Imunoterapia Adotiva , Melanoma Experimental/terapia , Proteínas Repressoras/metabolismo , Ribonucleases/metabolismo , Neoplasias Cutâneas/terapia , Linfócitos T/transplante , Ubiquitina-Proteína Ligases/metabolismo , Animais , Feminino , Células HEK293 , Células HeLa , Humanos , Imunidade Humoral , Masculino , Melanoma Experimental/genética , Melanoma Experimental/imunologia , Melanoma Experimental/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Fenótipo , Ligação Proteica , Proteínas Repressoras/genética , Ribonucleases/genética , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Microambiente Tumoral , Ubiquitina-Proteína Ligases/genéticaRESUMO
The structures of two new molecular complexes of antimony pentafluoride with pyridine (Py) and acetonitrile (AN), SbF5·Py and Sb2F10·AN, and a molecular complex of antimony trifluoride Sb2F6·Py and its ionic derivative [HPy]+[Sb2F7]- in the solid state have been determined by single crystal X-ray structural analysis. The complexes Sb2F10·AN and Sb2F6·Py are the first structurally characterized compounds of dimeric antimony fluorides. To reveal the nature of bonding in the complexes and their stability, DFT computations of the electronic structure and thermodynamic characteristics were performed, in particular the analysis of the electrostatic potentials, the orbital interactions and the topology. The results indicate that the intermolecular Sbâ¯F interactions can be described as a network of pnictogen bonds.
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The latest progress in alkaline anion-exchange membranes has led to the expectation that less costly catalysts than those of the platinum-group metals may be used in anion-exchange membrane fuel cell devices. In this work, we compare structural properties and the catalytic activity for the hydrogen-oxidation reaction (HOR) for carbon-supported nanoparticles of Ni, Ni3Co, Ni3Cu, and Ni3Fe, synthesized by chemical and solvothermal reduction of metal precursors. The catalysts are well dispersed on the carbon support, with particle diameter in the order of 10 nm, and covered by a layer of oxides and hydroxides. The activity for the HOR was assessed by voltammetry in hydrogen-saturated aqueous solutions of 0.1 mol dm-1 KOH. A substantial activation by potential cycling of the pristine catalysts synthesized by solvothermal reduction is necessary before these become active for the HOR; in situ Raman spectroscopy shows that after activation the surface of the Ni/C, Ni3Fe, and Ni3Co catalysts is fully reduced at 0 V, whereas the surface of the Ni3Cu catalyst is not. The activation procedure had a smaller but negative impact on the catalysts synthesized by chemical reduction. After activation, the exchange-current densities normalized with respect to the ECSA (electrochemically active surface area) were approximately independent of composition but relatively high compared to catalysts of larger particle diameter.
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AIMS: Valid measures to identify harmful alcohol use are important. Alcohol Use Disorders Identification Test (AUDIT) is a validated questionnaire used to self-report harmful drinking in several cultures and settings. Phosphatidylethanol 16:0/18:1 (PEth) is a direct alcohol biomarker measuring alcohol consumption levels. The aim of this study was to investigate how PEth levels correlate with AUDIT-QF and weekly grams of alcohol consumed among patients in two urban hospitals. In addition, we wanted to investigate the predictive value of PEth in identifying harmful alcohol use as defined by AUDIT-QF and weekly grams of alcohol cutoffs. METHODS: A cross-sectional study comprising acute medically ill patients with measurable PEth levels (≥0.030 µM) admitted to two urban hospitals in Oslo, Norway (N = 931) and Moscow, Russia (N = 953) was conducted using PEth concentrations in whole blood, sociodemographic data and AUDIT-QF questionnaires. RESULTS: PEth levels from patients with measurable PEth were found to be positively correlated with AUDIT-QF scores, with PEth cutpoints of 0.128 µM (Oslo) and 0.270 µM (Moscow) providing optimal discrimination for harmful alcohol use defined by AUDIT-QF (the difference between cities probably reflecting different national drinking patterns in QF). When converting AUDIT-QF into weekly grams of alcohol consumed, the predictive value of PEth improved, with optimal PEth cutpoints of 0.327 (Oslo) and 0.396 (Moscow) µM discriminating between harmful and non-harmful alcohol use as defined in grams (≥350 grams/week). CONCLUSIONS: By using PEth levels and converting AUDIT-QF into weekly grams of alcohol it was possible to get an improved rapid and sensitive determination of harmful alcohol use among hospitalized patients.
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Consumo de Bebidas Alcoólicas/sangue , Glicerofosfolipídeos/sangue , Biomarcadores/sangue , Estudos Transversais , Feminino , Hospitais , Humanos , Masculino , Noruega/epidemiologia , Valor Preditivo dos Testes , Curva ROC , Federação Russa/epidemiologia , AutorrelatoRESUMO
OBJECTIVES: The use of psychoactive prescription medication is increasing in the general population. This is a cause for concern, particularly among the elderly, where physiological changes related to senescence increase the risk for adverse effects. While previous studies regarding psychoactive substance use have generally been population based, we sought to determine the frequency of such use among acutely hospitalised patients. SETTING: Two emergency departments (EDs), one in Oslo and one in Moscow, admitting patients to Departments of Internal Medicine. PARTICIPANTS: 5583 patients aged ≥18 years participated, distributed evenly between genders and study locations. Patients unable to give informed consent were excluded. The study sites did not admit patients with surgical conditions and/or injuries. PRIMARY AND SECONDARY OUTCOMES: The presence of psychoactive substances was determined through blood analysis using liquid chromatography-mass spectrometry. Secondary outcomes comprised demographic data (including age, gender, employment and marital status), degree of psychological distress, concurrent alcohol use, and self-reported alcohol, psychoactive drug and illicit substance use. RESULTS: 32.3% in Oslo and 12% in Moscow were positive for one or more psychoactive medicinal drugs (benzodiazepines, z-hypnotics, opioids or barbiturates). In Oslo, medicinal drug use was associated with being aged 61 to 70 years (OR 2.40, 95% CI 1.61 to 3.58) compared with 18 to 40 years, and psychological distress (OR 2.61, 95% CI 2.06 to 3.30). In Moscow, psychoactive medicinal drug use was also associated with psychological distress (OR 1.68, 95% CI 1.18 to 2.39), and was less common among patients aged 41 to 60 years (OR 0.62, 95% CI 0.43 to 0.88) than among patients aged 18 to 40 years. CONCLUSION: A significant proportion of admitted patients used one or more psychoactive medicinal drugs, in particular benzodiazepines (Oslo and Moscow) and opiates (Oslo). We suggest formalised screening for inappropriate prescription drug use and increased adherence to clinical prescription guidelines.
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Transtornos Relacionados ao Uso de Substâncias , Adolescente , Adulto , Idoso , Consumo de Bebidas Alcoólicas , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Moscou/epidemiologia , Prevalência , Psicotrópicos , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Adulto JovemRESUMO
Weakly or "partially" bonded molecules are an important link between the chemical and van der Waals interactions. Molecular structures of six new SbBr3 -Py complexes in the solid state have been determined by single-crystal X-ray diffraction analysis. In all complexes all Sb atoms adopt a pseudo-octahedral coordination geometry which is completed by additional Sbâ â â Br contacts shorter than the sum of the van der Waals radii, with Br-Sbâ â â Br angles close to 180°. To reveal the nature of Sb-Br and Sb-N interactions, the DFT calculations were performed followed by the analysis of the electrostatic potentials, the orbital interactions and the topological analysis. Based on Natural Bond Orbital (NBO) analysis, the Sb-Br interactions range from the covalent bonds to the pnictogen bonds. A simple structural parameter, non-covalence criterion (NCC) is defined as a ratio of the atom-atom distance to the linear combination of sums of covalent and van der Waals radii. NCC correlates with E(2) values for Sb-N, Sb-Cl and Sb-Br bonds, and appears to be useful criterion for a preliminary evaluation of the bonding situation.
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Adenylate/uridylate-rich elements (AREs) are the most common cis-regulatory elements in the 3'-untranslated region (UTR) of mRNAs, where they fine-tune turnover by mediating mRNA decay. They increase plasticity and efficacy of mRNA regulation and are recognized by several ARE-specific RNA-binding proteins (RBPs). Typically, AREs are short linear motifs with a high content of complementary A and U nucleotides and often occur in multiple copies. Although thermodynamically rather unstable, the high AU-content might enable transient secondary structure formation and modify mRNA regulation by RBPs. We have recently suggested that the immunoregulatory RBP Roquin recognizes folded AREs as constitutive decay elements (CDEs), resulting in shape-specific ARE-mediated mRNA degradation. However, the structural evidence for a CDE-like recognition of AREs by Roquin is still lacking. We here present structures of CDE-like folded AREs, both in their free and protein-bound form. Moreover, the AREs in the UCP3 3'-UTR are additionally bound by the canonical ARE-binding protein AUF1 in their linear form, adopting an alternative binding-interface compared to the recognition of their CDE structure by Roquin. Strikingly, our findings thus suggest that AREs can be recognized in multiple ways, allowing control over mRNA regulation by adapting distinct conformational states, thus providing differential accessibility to regulatory RBPs.
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Elementos Ricos em Adenilato e Uridilato , Proteínas de Ligação a RNA/química , Ubiquitina-Proteína Ligases/química , Sítios de Ligação , Células HEK293 , Humanos , Simulação de Acoplamento Molecular , Motivos de Nucleotídeos , Ligação Proteica , Proteínas de Ligação a RNA/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The two most common types of ERP-based protocols to detect concealed information are the 3-stimulus protocol (3SP) and Complex Trial Protocol (CTP). Both protocols traditionally include presentation of a target (a stimulus with assigned significance requiring a unique behavioral response). The intention of the target presentation is forcing subjects to pay attention to all stimuli, especially to guilty knowledge stimuli, called probes. It was unclear though, how the presence of a targets influences probe recognition, and thus, the concealed information test (CIT) effect-the difference in P300 response to the probe and Irrelevant (crime-unrelated) stimuli. The question of target necessity was first raised in relation to the 3SP, and it was found that although omitting target stimuli reduced P300 amplitudes for all probe and irrelevant stimuli, the CIT effect was not reduced. The current study investigated how the presence or absence of the target/nontarget discrimination in the CTP affects the CIT effect, by comparing two CTP groups both with (T) and without (NT) the target/nontarget discrimination. The results demonstrated that this discrimination significantly increases the P300 effect. We found a greater P300 CIT effect in the T group than in the NT group, suggesting that for field use, it is better to retain the target discrimination in the CTP. CIT effects were also seen with P300 latency, but not reaction time.
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Enganação , Discriminação Psicológica/fisiologia , Potenciais Evocados P300/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Desempenho Psicomotor/fisiologia , Adolescente , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Previous research (Herring et al., 2011) indicated that certain types of incongruent verbal priming enhance responding to the subsequent (primed) stimuli. By priming participants in a P300-based Concealed Information Test (CIT), we examined the possible enhancement effects of priming stimuli in the P300 based Complex Trial Protocol (CTP) for face recognition. Participants were divided into two groups: one group with priming and one control group without. The probe (Pr) and irrelevants (Iall) of the two groups were faces, namely, pictures of the actor Tom Cruise (Pr) and of other unknown faces (Iall). One group had priming before Pr/Iall and one control group had no priming. The priming group was called the non-identical priming (NIP) group in which the verbal priming item (the name, "Bill Smith") is identical with neither Pr nor any of the Ialls. The group without priming is the control group which is called the non-priming group (NP) that simply experiences the basic Complex Trial Protocol. Results were that non-identical priming produced larger CIT effects than the control group, which is consistent with earlier findings. Also, the amplitude of the probe of the NIP group is larger than that of the NP group, while their irrelevants didn't show any significant difference. This means that the incongruent verbal priming did enhance the P300 CIT effect for the probe, which could further improve the accuracy of CTP for the concealed information test.
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Associação , Córtex Cerebral/fisiologia , Potenciais Evocados P300/fisiologia , Reconhecimento Facial/fisiologia , Adolescente , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Projetos de Pesquisa , Adulto JovemRESUMO
Engineered recombinant antibody-based reagents are rapidly supplanting traditionally derived antibodies in many cell biological applications. A particularly powerful aspect of these engineered reagents is that other modules having myriad functions can be attached to them either chemically or through molecular fusions. However, these processes can be cumbersome and do not lend themselves to high throughput applications. Consequently, we have endeavored to develop a platform that can introduce multiple functionalities into a class of Fab-based affinity reagents in a "plug and play" fashion. This platform exploits the ultra-tight binding interaction between affinity matured variants of a Fab scaffold (FabS ) and a domain of an immunoglobulin binding protein, protein G (GA1). GA1 is easily genetically manipulatable facilitating the ability to link these modules together like beads on a string with adjustable spacing to produce multivalent and bi-specific entities. GA1 can also be fused to other proteins or be chemically modified to engage other types of functional components. To demonstrate the utility for the Fab-GA1 platform, we applied it to a detection proximity assay based on the ß-lactamase (BL) split enzyme system. We also show the bi-specific capabilities of the module by using it in context of a Bi-specific T-cell engager (BiTE), which is a therapeutic assemblage that induces cell killing by crosslinking T-cells to cancer cells. We show that GA1-Fab modules are easily engineered into potent cell-killing BiTE-like assemblages and have the advantage of interchanging Fabs directed against different cell surface cancer-related targets in a plug and play fashion.
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Fragmentos Fab das Imunoglobulinas/genética , Proteínas do Tecido Nervoso/genética , Engenharia de Proteínas/métodos , Linhagem Celular , Humanos , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/metabolismo , Modelos Moleculares , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/metabolismo , Conformação Proteica , Domínios Proteicos , Proteínas Recombinantes/metabolismoRESUMO
Well-known research showed that the skin conductance response (SCR) of the Autonomic Nervous System (ANS) in the Concealed Information Test (CIT) is usually augmented in participants who are financially and motivationally incentivized to beat the CIT. This is not what happens with Reaction Time (RT)-based CITs, P300 CITs based on the 3-stimulus protocol, nor on the P300-based complex trial protocol for detection of malingering (however these tests differ from forensic CITs). The present report follows up the Rosenfeld et al. (1, 2) study of motivated malingerers instructed how to beat the test, with uninstructed motivated (paid and unpaid) and unmotivated ("simple malingering") subjects, using episodic and semantic memory probes. The Test of Memory Malingering (TOMM) validated behavioral differences among groups. The "CIT effect" (probe-minus-irrelevant P300 differences) did not differ among incentive groups, although as previously, semantic memory-evoked P300s exceeded episodic memory evoked P300s. An effect of specific test-beating instructions was found to enhance the CIT effect for semantic information.
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The vast majority of platforms for the detection of viral or bacterial antigens rely on immunoassays, typically ELISA or sandwich ELISA, that are contingent on the availability of suitable monoclonal antibodies (mAbs). This is a major bottleneck, since the generation and production of mAbs is time-consuming and expensive. Synthetic antibody fragments (sFabs) generated by phage-display selection offer an alternative with many advantages over Fabs obtained from natural antibodies using hybridoma technology. Unlike mAbs, sFabs are generated using phage display, allowing selection for binding to specific strains or for pan-specificity, for identification of structural epitopes or unique protein conformations and even for complexes. Further, they can easily be produced in Escherichia coli in large quantities and engineered for purposes of detection technologies and other applications. Here, the use of phage-display selection to generate a pan-specific Fab (MJ20), based on a Herceptin Fab scaffold, with the ability to bind selectively and with high affinity to the C-terminal domains of the nucleoproteins (NPs) from all five known strains of the Ebola virus is reported. The high-resolution crystal structure of the complex of MJ20 with the antigen from the Bundibugyo strain of the Ebola virus reveals the basis for pan-specificity and illustrates how the phage-display technology can be used to manufacture suitable Fabs for use in diagnostic or therapeutic applications.
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Complexo Antígeno-Anticorpo/química , Ebolavirus/química , Fragmentos Fab das Imunoglobulinas/química , Nucleoproteínas/química , Técnicas de Visualização da Superfície Celular , Cristalografia por Raios X , Humanos , Fragmentos de Imunoglobulinas/química , Biblioteca de Peptídeos , Ligação Proteica , Domínios ProteicosRESUMO
The ubiquitously expressed RNA-binding proteins Roquin-1 and Roquin-2 are essential for appropriate immune cell function and postnatal survival of mice. Roquin proteins repress target mRNAs by recognizing secondary structures in their 3'-UTRs and by inducing mRNA decay. However, it is unknown if other cellular proteins contribute to target control. To identify cofactors of Roquin, we used RNA interference to screen ~1500 genes involved in RNA-binding or mRNA degradation, and identified NUFIP2 as a cofactor of Roquin-induced mRNA decay. NUFIP2 binds directly and with high affinity to Roquin, which stabilizes NUFIP2 in cells. Post-transcriptional repression of human ICOS by endogenous Roquin proteins requires two neighboring non-canonical stem-loops in the ICOS 3'-UTR. This unconventional cis-element as well as another tandem loop known to confer Roquin-mediated regulation of the Ox40 3'-UTR, are bound cooperatively by Roquin and NUFIP2. NUFIP2 therefore emerges as a cofactor that contributes to mRNA target recognition by Roquin.
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Linfócitos T CD4-Positivos/imunologia , Proteína Coestimuladora de Linfócitos T Induzíveis/genética , Proteínas Nucleares/genética , Proteínas de Ligação a RNA/genética , Receptores OX40/genética , Proteínas Repressoras/genética , Ubiquitina-Proteína Ligases/genética , Sequência de Aminoácidos , Animais , Sítios de Ligação , Linfócitos T CD4-Positivos/citologia , Regulação da Expressão Gênica , Células HEK293 , Células HeLa , Humanos , Proteína Coestimuladora de Linfócitos T Induzíveis/antagonistas & inibidores , Proteína Coestimuladora de Linfócitos T Induzíveis/imunologia , Sequências Repetidas Invertidas , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/imunologia , Conformação de Ácido Nucleico , Cultura Primária de Células , Ligação Proteica , Estabilidade de RNA , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/imunologia , Receptores OX40/antagonistas & inibidores , Receptores OX40/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Repressoras/imunologia , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Ubiquitina-Proteína Ligases/imunologiaRESUMO
Previous research indicated that the skin conductance response of the autonomic nervous system in the Concealed Information Test (CIT) is typically increased in subjects who are financially and otherwise incentivized to defeat the CIT (the paradoxical "motivational impairment" effect). This is not the case for RT-based CITs, nor P300 tests based on the three-stimulus protocol for detection of cognitive malingering (although these are not the same as CITs). The present report is the first attempt to study the effect of financial motivation on the P300-based Complex Trial Protocol using both episodic and semantic memory probe and irrelevant stimuli. The Test of Memory Malingering (TOMM) was used to validate behavioral differences between the two groups we created by offering one (paid) group but not another (unpaid) group a financial reward for beating our tests. Group behavioral differences on the TOMM did confirm group manipulations. Probe-minus-irrelevant P300 differences did not differ between groups, although as previously, semantic memory-evoked P300s were larger than episodic memory-evoked P300s.
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Córtex Cerebral/fisiologia , Potenciais Evocados P300 , Memória Episódica , Memória/fisiologia , Motivação/fisiologia , Recompensa , Semântica , Adolescente , Adulto , Enganação , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Tempo de Reação , Adulto JovemRESUMO
Complex beryllium amidoboranes Mx [Be(NH2 BH3 )x+2 ] (M = Li-Cs, x = 1,2) have been computationally studied at M06-2X/def2-TZVPPD//B3LYP/def2-TZVPPD level of theory. Compounds are predicted to be stable at room temperature but release H2 on heating. Agostic Be HB bonds play an important role in stabilization of oligomeric beryllium imidoboranes. Polymeric imidoborane, hydrogen, and ammonia are expected as major thermal decomposition products of complex beryllium amidoboranes. Ammonia evolution is predicted to proceed at slightly higher temperatures than hydrogen evolution. Based on thermodynamic analysis, Li[Be(NH2 BH3 )3 ] and Li2 [Be(NH2 BH3 )4 ] are the most perspective synthetic targets. Synthetic approaches to these potentially efficient hydrogen storage materials have been proposed. © 2016 Wiley Periodicals, Inc.
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A systematic structural study of complexes formed by aluminium and gallium trihalides with 4,4'-bipyridine (bipy) in 2 : 1, 1 : 1, and 1 : 2 stoichiometric ratios has been performed. Molecular structures of 11 complexes in the solid state have been determined for the first time. Complexes of 2 : 1 composition are molecular, while complexes of 1 : 1 composition form metal-organic frameworks of different kinds: an ionic 3D network (three interpenetrated lvt nets for AlCl3bipy), an ionic 2D network for AlBr3bipy and GaBr3bipy and a 1D coordination polymer in the case of GaCl3bipy. Thus, the nature of the Lewis acid plays a critical role in the structural type of the complex in the solid state. Incorporation of excess bipy molecules into (GaCl3bipy)∞ (formation of crystallosolvate) leads to an unprecedented change of the molecular structure from a non-ionic 1D coordination polymer to an ionic 2D metal organic framework [GaCl2bipy2](+)[GaCl4](-)·2bipy. As indicated by the temperature-dependent XRD study, removal of bipy by heating in a vacuum restores the non-ionic 1D structure. Quantum chemical computations for simple cluster model systems (up to eight Al and Ga atoms) reveal that ionic forms are slightly favourable, although the energy differences between the ionic and non-ionic structures are not large. These theoretical predictions are in good agreement with experimental findings. Thus, even relatively simple cluster models may be used to indicate the structural preferences in the solid state. Both experimental and computational IR frequency shifts of the in-plane ring bending mode of bipy upon complexation correlate well with the M-N bond distances in the complexes.
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Clostridium litorale is a Gram-positive, rod-shaped, and spore-forming bacterium, which is able to use amino acids such as glycine, sarcosine, proline, and betaine as single carbon and energy sources via Stickland reactions. The genome consists of a circular chromosome (3.41 Mb) and a circular plasmid (27 kb).