An Unusual Microdomain Factor Controls Interaction of Organic Halides with the Palladium Phase and Influences Catalytic Activity in the Mizoroki-Heck Reaction.

In this work, using a combination of scanning and transmission electron microscopy (SEM and TEM), the transformations of palladium-containing species in imidazolium ionic liquids in reaction mixtures of the Mizoroki-Heck reaction and in related organic media are studied to understand a challenging question of the relative reactivity of organic halides as key substrates in modern catalytic technologies. The microscopy technique detects the formation of a stable nanosized palladium phase under the action of an aryl (Ar) halide capable of forming microcompartments in an ionic liquid. For the first time, the correlation between the reactivity of the aryl halide and the microdomain structure is observed: Ar-I (well-developed microdomains) > Ar-Br (microphase present) > Ar-Cl (minor amount of microphase). Previously, it is assumed that molecular level factors, namely, carbon-halogen bond strength and the ease of bond breakage, are the sole factors determining the reactivity of aryl halides in catalytic transformations. The present work reports a new factor connected with the nature of the organic substrates used and their ability to form a microdomain structure and concentrate metallic species, highlighting the importance of considering both the molecular and microscale properties of the reaction mixtures.

Inside Block Copolymer Micelles-Tracing Interfacial Influences on Crosslinking Efficiency in Nanoscale Confined Spaces.

Recently, several studies have demonstrated the excellent capabilities of tip-enhanced Raman spectroscopyfor in-depth investigations of structural properties of matter with unprecedented resolution and chemical specificity. These capabilities are utilized here to study the internal structure of core-crosslinked micelles, which are formed by self-assembly of the diblock terpolymer poly(ethylene oxide)-block-poly(furfuryl glycidylether-co-tert-butylglycidyl ether). Supplementing force-volume atomic force microscopy experiments address additionally the nanomechanical properties. Particularly, TERS enables investigating the underlying principles influencing the homogeneity and efficiency of the Diels-Alder core-crosslinking process in the confined hydrophobic core. While the central core region is homogenously crosslinked, a breakdown of the crosslinking reaction is observed in the core-corona interfacial region. The results corroborate that a strong crosslinking efficiency is directly correlated to the formation of a mixed zone of the glycidyl ether and PEO corona blocks reaching ≈5 nm into the core region. Concomitantly a strong exclusion of the encapsulated bismaleimide crosslinker from the interfacial region is observed. It is conceivable that a changed structure, chemical composition and altered nanomechanical properties of this interfacial region may also influence the crosslinking efficiency across the entire core region by a modification of the solubility of the crosslinker in the interfacial core-corona region.

Enhanced Catalysis under 2D Silica: A CO Oxidation Study.

Interfacially confined microenvironments have recently gained attention in catalysis, as they can be used to modulate reaction chemistry. The emergence of a 2D nanospace at the interface between a 2D material and its support can promote varying kinetic and energetic schemes based on molecular level confinement effects imposed in this reduced volume. We report on the use of a 2D oxide cover, bilayer silica, on catalytically active Pd(111) undergoing the CO oxidation reaction. We "uncover" mechanistic insights about the structure-activity relationship with and without a 2D silica overlayer using in situ IR and X-ray spectroscopy and mass spectrometry methods. We find that the CO oxidation reaction on Pd(111) benefits from confinement effects imposed on surface adsorbates under 2D silica. This interaction results in a lower and more dispersed coverage of CO adsorbates with restricted CO adsorption geometries, which promote oxygen adsorption and lay the foundation for the formation of a reactive surface oxide that produces higher CO2 formation rates than Pd alone.

In Situ Probing of the Particle-Mediated Mechanism of WO3 -Networked Structures Grown inside Confined Mesoporous Channels.

Nanocasting, using ordered mesoporous silica or carbon as a hard template, has enormous potential for preparing novel mesoporous materials with new structures and compositions. Although a variety of mesoporous materials have been synthesized in recent years, the growth mechanism of nanostructures in a confined space, such as mesoporous channels, is not well understood, which hampers the controlled synthesis and further application of mesoporous materials. Here, the nucleation and growth of WO3 -networked mesostructures within an ordered mesoporous matrix, using an in situ transmission electron microscopy heating technique and in situ synchrotron small-angle X-ray scattering spectroscopy, are probed. It is found that the formation of WO3 mesostructures involves a particle-mediated transformation and coalescence mechanism. The liquid-like particle-mediated aggregation and mesoscale transformation process can occur in ≈10 nm confined mesoporous channels, which is completely unexpected. The detailed mechanistic study will be of great help for experimental design and to exploit a variety of mesoporous materials for diverse applications, such as catalysis, absorption, separation, energy storage, biomedicine, and nanooptics.

Comparison of Airway Management Methods in Entrapped Patients: A Manikin Study.

INTRODUCTION: Endotracheal intubation remains one of the most challenging skills in prehospital care. There is a minimal amount of data on the optimal technique to use when managing the airway of an entrapped patient. We hypothesized that use of a blindly placed device would result in both the shortest time to airway management and highest success rate. METHODS: A difficult airway manikin was placed in a cervical collar and secured upside down in an overturned vehicle. Experienced paramedics and prehospital registered nurses used four different methods to secure the airway: direct laryngoscopy, digital intubation, King LT-D, and CMAC video laryngoscopy. Each participant was given three opportunities to secure the airway using each technique in random order. A study investigator timed each attempt and confirmed successful placement, which was determined upon inflation of the manikin's lungs. Intubation success rates were analyzed using a general estimating equations model to account for repeated measures and a linear mixed effects model for average time. RESULTS: Twenty-two prehospital providers participated in the study. The one-pass success rate for the King LT-D was significantly higher than direct laryngoscopy (OR 0.048, CI 0.006-0.351, p < 0.01) and digital intubation (OR 0.040, CI 0.005-0.297, p < 0.01). However, there was no statistical difference between the one-pass success rate of the King LT-D and CMAC video laryngoscopy (OR 0.302, 95% CI 0.026-3.44, p = 0.33). The one-pass median placement time of the King LT-D (22 seconds, IQR 17-26) was significantly lower (p < 0.001) than direct laryngoscopy (60 seconds, IQR 42-75), digital intubation (38 seconds, IQR 26-74), and the CMAC (51 seconds, IQR 43-76). CONCLUSIONS: In this study, while the King LT-D offered the quickest airway placement, success rates were not significantly greater than intubation using the CMAC video laryngoscope. Intubation using direct laryngoscopy and digital intubation were less successful and took more time. Use of a blindly placed device or a video laryngoscope may provide the best avenues for airway management of entrapped patients.

Evaluation of RPE-Select: A Web-Based Respiratory Protective Equipment Selector Tool.

This article describes the evaluation of an open-access web-based respiratory protective equipment selector tool (RPE-Select, accessible at http://www.healthyworkinglives.com/rpe-selector). This tool is based on the principles of the COSHH-Essentials (C-E) control banding (CB) tool, which was developed for the exposure risk management of hazardous chemicals in the workplace by small and medium sized enterprises (SMEs) and general practice H&S professionals. RPE-Select can be used for identifying adequate and suitable RPE for dusts, fibres, mist (solvent, water, and oil based), sprays, volatile solids, fumes, gases, vapours, and actual or potential oxygen deficiency. It can be applied for substances and products with safety data sheets as well as for a large number of commonly encountered process-generated substances (PGS), such as poultry house dusts or welding fume. Potential international usability has been built-in by using the Hazard Statements developed for the Globally Harmonised System (GHS) and providing recommended RPE in picture form as well as with a written specification. Illustration helps to compensate for the variabilities in assigned protection factors across the world. RPE-Select uses easily understandable descriptions/explanations and an interactive stepwise flow for providing input/answers at each step. The output of the selection process is a report summarising the user input data and a selection of RPE, including types of filters where applicable, from which the user can select the appropriate one for each wearer. In addition, each report includes 'Dos' and 'Don'ts' for the recommended RPE. RPE-Select outcomes, based on up to 20 hypothetical use scenarios, were evaluated in comparison with other available RPE selection processes and tools, and by 32 independent users with a broad range of familiarities with industrial use scenarios in general and respiratory protection in particular. For scenarios involving substances having safety data sheets, 87% of RPE-Select outcomes resulted in a 'safe' RPE selection, while 98% 'safe' outcomes were achieved for scenarios involving process-generated substances. Reasons for the outliers were examined. User comments and opinions on the mechanics and usability of RPE-Select are also presented.

Distinct selectivity inside self-assembled coordination cages.

Supramolecular containers have long been applied to regulate organic reactions with distinct selectivity, owing to their diverse functions such as the ability to pose a guest molecule(s) with a certain orientation and conformation. In this review, we try to illustrate how self-assembled coordination cages could achieve this goal. Two representative cage hosts, namely, self-assembled Pd(II)-ligand octahedral coordination cages ([Pd6L4]12+) and self-assembled Ga(III)-ligand tetrahedral coordination cages ([Ga4L6]12-) are selected as the pilot hosts that this mini review covers. Representative works in this area are presented here in brief.

Identifying the contribution of charge effects to airborne transmission of aerosols in confined spaces.

Aerosols in indoor air have various adverse effects on human health. Considering the use of forced ventilation and fan mixing (individually and in combination), the variation in charge number and their effects on aerosol transmission in confined spaces were explored in this study with the distinction of particle sources. In the case of sources originating from the external space, natural penetration acquires a greater number of negative charges. Forced ventilation of a confined space acts on the fate of particles in the neighboring confined space, while the internal fan has a negligible effect on both the number concentration and charge number of particles in the exterior. The combination of forced ventilation and fan mixing increases charge numbers, altering the lifetime of particles in the external regional environment by deposition or adsorption, particularly for neutralized particles. In the case of sources originating from the interior area, application of an internal fan weakens the ventilation effect from forced ventilation, resulting in internal particle loss by depositing on internal surfaces due to electrostatic charge, increasing the potential risk of resuspension. Additionally, source origin is associated with particle fate, and the charge generated under the action of external forces contributes to the transmission pathways and the fate of the particles in the air. This study investigates the transmission pathways and the fate of aerosols from the perspective of charge number, hopefully contributing to an in-depth understanding of the transmission mechanisms of toxic substances in confined spaces with aerosols as carriers.

Unusual Pd nanoparticle dispersion in microenvironment for p-nitrophenol and methylene blue catalytic reduction.

Palladium based catalysts are highly attractive for catalytic reactions. However, the catalytic activity is dependent on the dispersion and size of Pd nanoparticles (NPs). Herein, an efficient strategy is developed to regulate the size and dispersion of Pd NPs in nanoconfined spaces provided by Santa Barbara Amorphous-15 (SBA-15) occluded with template. The Pd precursor is introduced to the confined spaces between the template and silica walls in as-synthesized SBA-15 (AS) by grinding. Subsequent reduction allow template removal and precursor conversion to Pd0 in single step and avoids aggregation that take place in calcined SBA-15 (CS). Our results show that up to 1.0 wt% of Pd can be well dispersed in confined spaces of AS (denoted as 1.0PdAS), while sever aggregation take place from CS with the same Pd loading (denoted as1.0PdCS). We also demonstrated that 1.0PdAS is highly efficient for catalytic reduction of p-nitrophenol (P-NP) and Methylene blue (MB) with rate constant of 0.4924 and 0.626 min-1, respectively, which is superior than 1.0PdCS attributed to well dispersed and smaller size (3 nm) Pd NPs. Furthermore, no change in the rate constant of P-NP (0.4924 min-1) and MB (0.626 min-1) after regeneration presents good stability of 1.0PdAS in catalytic reactions.

Fabrication of 3-D confined spaces with Au NPs: Superior dispersion and catalytic activity.

Gold nanoparticles (Au NPs) as an active noble-metal site have received great attention because of its superior catalytic activity in diverse reactions. However, the activity of Au NPs is strongly dependent on its size and dispersion degree. Therefore, we developed an efficient solid-state reduction (SSR) strategy for the first time to promote the dispersion degree and size of Au NPs in template-occluded KIT-6 (AK) as a support by taking advantage of (i) 3-dimentonal cubic mesoporous structure of support (ii) confined spaces present between template (Pluronic (P) 123) and silica wall of AK where Au NPs locate (iii) interaction of both P123 as template and silica walls of AK with Au NPs highly efficient for Au NPs dispersion and (iv) SSR strategy which avoids competitive adsorption of solvent in the conventional fabrication process. The results revealed that Au-based AK (AuAK) has much better dispersion of Au NPs with smaller sizes than template-free KIT-6 (CK). Moreover, the catalytic activity of AuAK in reduction reactions of p-nitrophenol (P-NP) to p-aminophenol (P-AP) and Methylene blue (MB) to Leuco MB (LMB) is superior than AuCK as well as to those Au-catalysts synthesized via conventional strategies previously. The catalytic performance is also related well with characterization results.

Asphyxiation death caused by oxygen-depleting cargo on a ship.

The extreme danger associated with entering enclosed spaces loaded with oxygen-depleting organic cargo in ships and tanks is obviously underestimated, both among crew and management. We present a case report to highlight this occupational hazard and to increase the knowledge about the imperative precautions, in order to prevent future accidents. An experienced customs officer was found lifeless at the bottom of the unattended cargo hold on a ship loaded with woodchips. The oxygen content in the cargo atmosphere was below 2%, which is incompatible with life. Forensic autopsy revealed injuries related to the fall, and there were no positive toxicological findings in blood, lung or urine. Management and workers must be taught about the extreme rapidity of developing unconsciousness and asphyxiant death when entering enclosed spaces loaded with oxygen-depleting cargo. Even a single inhalation can result in unconsciousness and death. Dozens of annual deaths and severe injuries can easily be prevented if simple precautions are followed.

Neuroelectrophysiological mechanism of disabling brain injury resulting from exposure of rat to blast in a tightly closed compartment / 解放军医学杂志

ObjectiveTo explore the dynamic changes in disabling brain injury in a closed compartment, and its underlying neuroelectrophysiological mechanism after exposure of rats to blast. MethodsSixty-eight SD rats were randomly divided into control group, OTB group ( blast in an open space), and ECB group (blast in a tightly closed compartment). ECB and OTB groups were exposed to blast in a closed chamber simulating the cabin of an armored vehicle and OT (outside of the cabin) with 600-mg detonator electric blasting and 21.5-cm away from the detonating point. The changes of disabled ischemic area of the brain and evoked potential before and 1, 3, 5, 8, 12, 24h and 72h after the blast injury were observed. ResultsThe incapability score of ECB and OTB rats reached the same level (25%). With 3, 5-triphenyltetrazolium chloride staining, it was found that the infarct area in OTB group appeared 5h after explosion, reaching the climax at 12h, and disappearing at 72h. In the ECB group, the area of infarct appeared 3h after injury, and still existed till 72h after injury. In ECB group, the N1 latency of sensory evoked potential (SEP) and motor evoked potential (MEP) was longer than that of control group 5 and 8 hours after explosion respectively, and the changes in sensation appeared earlier than those of motor function. ConclusionsThe blast wave in EC shows a characteristic of a complex blast wave, and its damage to the brain can be more severe, which is caused more by ECB than by OTB. The size of infarct area and latency of evoked potential might contribute to the brain incapability.

Elaboração de instrumento para identificação de fatores de risco psicossocial associados à atuação em espaços confinados / Elaboration of an instrument to identify psychosocial risk factors associated with working in confined spaces

No Brasil, são poucas as pesquisas desenvolvidas sobre mensuração dos fatores de risco psicossocial no trabalho em espaço confinado. Na maior parte dos estudos envolvendo essa temática são utilizados instrumentos para ambientes ou contextos em geral, sem considerar as especificidades do local. Dessa forma, é relevante a disponibilização de instrumentos específicos que possam auxiliar a construção do conhecimento em saúde do trabalhador. O objetivo deste estudo foi elaborar um instrumento de percepção dos fatores de risco psicossocial para trabalhadores que, dentre suas atividades laborais, executam atividades em espaços confinados. Trata-se de investigação metodológica desenvolvida junto à trabalhadores brasileiros de uma empresa de grau de nível elétrico 3, seguindo quatro etapas: 1) revisão da literatura e entrevista com trabalhadores para identificação dos atributos associados à percepção dos fatores de risco psicossocial no trabalho em espaço confinado; 2) categorização das falas em classes e elaboração dos itens; 3) validação semântica dos itens e escala de resposta e 4) validação de conteúdo dos mesmos com especialistas da área e com trabalhadores. Participaram das entrevistas e da validação semântica 50 e 18 trabalhadores, respectivamente. Da etapa de validação de conteúdo participaram 22 juízes, sendo 16 especialistas em fatores de risco psicossocial ou elaboração e validação de instrumentos e seis representantes da população que analisaram a relevância, a representatividade, a clareza e o formato dos itens, assim como das questões de caracterização dos trabalhadores. As variáveis de caracterização foram descritas por distribuições de frequências e medidas de tendência central e de dispersão. A validação semântica foi conduzida mediante aplicação de questionários DISABKIDS® adaptados com resultados apresentados em frequências absolutas e percentuais. O conteúdo das entrevistas foi organizado em corpus linguístico com as falas categorizadas segundo o referencial teórico adotado. O software Interface de R pour les Analyses Multidimensionnelles de Textes et de Questionnaires foi utilizado para auxiliar a categorização das falas em classes. A validade de conteúdo foi analisada pelo Índice de Validade de Conteúdo. As falas foram categorizadas em cinco classes associadas aos atributos de risco psicossocial no trabalho: carga e ritmo de trabalho e papel na organização e relacionados ao trabalhador: planejamento das tarefas; relações interpessoais no ambiente de trabalho e interface casa-trabalho, a partir dos quais foram elaborados 46 itens. As sugestões, na validação semântica, geraram mudanças na forma da redação de 24 e acréscimo de seis itens. Na validação de conteúdo as sugestões geraram mudanças na forma e na redação de 36 e exclusão de sete, totalizando 45, que foram redistribuídos em oito atributos de risco psicossocial, nos cinco anteriores mais ambiente e equipamentos; função e cultura organizacional e latitude de decisão/controle. Estes foram distribuídos nos domínios "contexto" e "conteúdo". Os itens foram considerados importantes pelos participantes e pelos juízes desde sua primeira concepção e os resultados corroboraram sua aplicabilidade. O instrumento elaborado, dando voz aos trabalhadores, considera os aspectos psicossociais a partir de sua percepção e poderá subsidiar tomada de decisão no gerenciamento do trabalho em espaço confinado e na promoção da saúde mental dessa população

In Brazil, few studies have been carried out on the measurement of psychosocial risk factors related to work in confined spaces. In most studies involving this theme, instruments are used for environments or contexts in general, without considering the specificities of the place. Therefore, it is relevant to make specific instruments available that may help the construction of knowledge on workers' health. The aim of this study was to design an instrument for the perception of psychosocial risk factors for workers who, in their work activities, perform activities in confined spaces. This was a methodological study developed with Brazilian workers of a level 3 electrical company, following four stages: 1) literature review and interview with workers to identify the attributes associated with the perception of the psychosocial risk factors in confined space work; 2) categorization of the statements into classes and elaboration of items; 3) semantic validation of the items and response scale and 4) content validation of these with specialists of the area and with workers. A total of 50 workers participated in the interviews and 18 in the semantic validation. Regarding the content validation stage, 22 judges participated, of which 16 were specialists in psychosocial risk factors or the design and validation of instruments and six representatives of the population, who analyzed the relevance, representativeness, clarity and format of the items as well as the questions for the characterization of the workers. The characterization variables were described by frequency distributions and measures of central tendency and dispersion. Semantic validation was carried out through the application of adapted DISABKIDS® questionnaires, with the results presented in absolute frequencies and percentages. The content of the interviews was organized in a linguistic corpus with the statements categorized according to the theoretical framework adopted. The R interface for multidimensional analysis of texts and questionnaires software was used to support the categorization of the statements into classes. The content validity was analyzed through the Content Validity Index. The statements were categorized into five classes associated with the psychosocial risk at work attributes: workload and rhythm and role in organization, and related to the worker: task planning; interpersonal relations at work and homework interface, from which 46 items were designed. The suggestions in the semantic validation generated changes in the writing of 24 items and an increase of six items. In the content validation the suggestions generated changes in the form and in the writing of 36 items and the exclusion of seven, totaling 45 items, which were redistributed in eight psychosocial risk attributes, these being the five previous as well as environment and equipment; organizational function and culture; and latitude in decisions/control. These were distributed in the "context" and "content" domains. The items were considered important by the participants and the judges from their first concept and the results corroborated their applicability. The elaborated instrument, giving voice to the workers, considers the psychosocial aspects based on their perception and may support decision making in the management of work in confined spaces and in the promotion of the mental health of this population

El ambiente laboral como fuente de exposición a humo de tabaco ambiental: Estudio en trabajadores de bares y restaurantes de Santiago, Chile / The work environment as a source of exposure to secondhand smoke: a study in workers of bars and restaurants of Santiago, Chile

Background: Secondhand smoke (SHS) is an established cause of morbidity and mortality among non-smokers. The workplace is an important source of exposure, especially among workers of restaurants, bars and nightclubs. Aim: To estimate the daily occupational exposure to SHS among non-smoking workers of bars and restaurants of Santiago, Chile. Material and Methods: Environmental vapor-phase nico-tine was measured for 95 non-smoking workers of bars and restaurants of Santiago, using passive personal samplers during a daily work shift and outside the workplace. Results: The median occupational exposure to air nicotine was 9.18 µg/m³ (P25-P75 3.15-25.67 µg/m³). Higher concentrations were found among workers of places with no smoking restrictions (22.72 µg/m³; P25-P75 5.73-34.85 µg/m³), bar workers (20.75 µg/m³, P25-P75 5.03-44.67 µg/m³), waiters (20.57 µg/m³, PP25-P75 5.66-42.73 µg/m3) and bartenders (10.37 µg/m³, P25-P75 9.75-25.67 µg/m³). The median concentration of nicotine outside the workplace was 1.79 µg/m³ (P25-P75 1.02-3.00 µg/m³). Occupational exposure was 4.77 times higher compared to the non-work exposure. Conclusions: Workers of bars and restaurants are exposed to high levels of SHS at the workplace. Moreover, occupational exposure among these non-smoking workers is, in most cases, the main source of daily exposure to this pollutant.