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1.
Stress Health ; 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33277820

RESUMO

While researchers have begun to investigate theory and methods related to attenuating stress-related issues at work, one underexplored area is barriers to reporting stress-related concerns in the workplace. Research on organizational climate broadly covers psychosocial safety at work. However, the literature has not examined other, more specific factors such as stigma toward reporting stress-related concerns in the workplace. Using a prospective design, the current study examined the distinction between psychosocial safety climate (PSC) and stigmas surrounding reporting stress that may exist in organizations. Furthermore, we investigated whether PSC would buffer against the effects of such stigmas. The findings of this study indicate that stigma and PSC are distinct and can independently predict psychosocial outcomes. The results also indicate that PSC may play a role in attenuating the effects of these stigmas on some psychosocial outcomes. Implications and potential avenues for future research in this area are discussed. This article is protected by copyright. All rights reserved.

2.
Appl Psychol ; 2020 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-33362328

RESUMO

Workers and their families bear much of the economic burden of COVID-19. Even though they have declined somewhat, unemployment rates are considerably higher than before the start of the pandemic. Many workers also face uncertainty about their future employment prospects and increasing financial strain. At the same time, the workplace is a common source of transmission of COVID-19 and many jobs previously seen as relatively safe are now viewed as potentially hazardous. Thus, many workers face dual threats of economic stress and COVID-19 exposure. This paper develops a model of workers' responses to these dual threats, including risk perception and resource depletion as mediating factors that influence the relationship of economic stress and occupational risk factors with COVID-19 compliance-related attitudes, safe behavior at work, and physical and mental health outcomes. The paper also describes contextual moderators of these relationships at the individual, unit, and regional level. Directions for future research are discussed.

3.
Nanoscale ; 12(46): 23768-23779, 2020 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-33232431

RESUMO

The ability to tune the localized surface plasmon resonance (LSPR) of nanostructures is desirable for surface enhanced Raman spectroscopy (SERS), plasmon-assisted chemistry and other nanophotonic applications. Although historically the LSPR is mainly studied by optical techniques, with the recent advancement in electron monochromators and correctors, it has attracted considerable attention in transmission electron microscopy (TEM). Here, we use electron energy loss spectroscopy (EELS) in a scanning TEM to study individual gold nanodiscs and bowties in lithographic arrays with variable LSPRs by adjusting the size, interspacing, shape and dielectric environment during the nanofabrication process. We observe the strongest Raman signal enhancement when the LSPR frequency is close to the incident laser frequency in Raman spectroscopy. A simplified harmonic oscillator model is used to estimate SERS enhancement factor (EF) from EELS, bridging the connection between electron and photon excitation of plasmonic arrays. This work demonstrates that STEM-EELS shows promise for revealing the contributions of specific LSPR modes to SERS EF. Our results provide guidelines to fine-tune nanoparticle parameters to deliver the maximum signal enhancement in biosensing applications, such as early cancer detection.

4.
Adv Mater ; 32(37): e2003020, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32743836

RESUMO

Forming pits on molybdenum disulfide (MoS2 ) monolayers is desirable for (opto)electrical, catalytic, and biological applications. Thermal oxidation is a potentially scalable method to generate pits on monolayer MoS2 , and pits are assumed to preferentially form around undercoordinated sites, such as sulfur vacancies. However, studies on thermal oxidation of MoS2 monolayers have not considered the effect of adventitious carbon (C) that is ubiquitous and interacts with oxygen at elevated temperatures. Herein, the effect of adventitious C on the pit formation on MoS2 monolayers during thermal oxidation is studied. The in situ environmental transmission electron microscopy measurements herein show that pit formation is preferentially initiated at the interface between adventitious C nanoparticles and MoS2 , rather than only sulfur vacancies. Density functional theory (DFT) calculations reveal that the C/MoS2 interface favors the sequential adsorption of oxygen atoms with facile kinetics. These results illustrate the important role of adventitious C on pit formation on monolayer MoS2 .

5.
Occup Health Sci ; : 1-22, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32838031

RESUMO

Workers bear a heavy share of the burden of how countries contend with COVID-19; they face numerous serious threats to their occupational health ranging from those associated with direct exposure to the virus to those reflecting the conflicts between work and family demands. Ten experts were invited to comment on occupational health issues unique to their areas of expertise. The topics include work-family issues, occupational health issues faced by emergency medical personnel, the transition to telework, discrimination against Asian-Americans, work stressors, presenteeism, the need for supportive supervision, safety concerns, economic stressors, and reminders of death at work. Their comments describe the nature of the occupational health concerns created by COVID-19 and discuss both unanswered research questions and recommendations to help organizations reduce the impacts of COVID-19 on workers.

6.
Australas J Dermatol ; 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32840870

RESUMO

While a wide range of treatments exist for actinic keratosis and skin field cancerisation, the long-term benefits of the most common topical therapies are poorly defined. This report reviews the efficacy of the most commonly used topical therapies to treat regional or field lesions. Limited clinical and histopathological data are available on clearance rates at 12 months post-treatment for the most commonly used agents, with varied outcome measures making any comparison difficult. In general, total field clearance rates at 12 months are suboptimal for the most commonly employed agents. Given the increasing incidence of actinic keratosis and skin field cancerisation due to an ageing population, further research into the efficacy of therapies is critical to guide treatment choice.

7.
Adv Mater ; 32(36): e2003213, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32720366

RESUMO

Controlling the structure of graphene and graphene oxide (GO) phases is vitally important for any of its widespread intended applications: highly ordered arrangements of nanoparticles are needed for thin-film or membrane applications of GO, dispersed nanoparticles for composite materials, and 3D porous arrangements for hydrogels. By combining coarse-grained molecular dynamics and newly developed accurate models of GO, the driving forces that lead to the various morphologies are resolved. Two hydrophilic polymers, poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA), are used to illustrate the thermodynamically stable morphologies of GO and relevant dispersion mechanisms. GO self-assembly can be controlled by changing the degree of oxidation, varying from fully aggregated over graphitic domains to intercalated assemblies with polymer bilayers between sheets. The long-term stability of a dispersion is extremely important for many commercial applications of GO composites. For any degree of oxidation, GO does not disperse in PVA as a thermodynamic equilibrium product, whereas in PEG dispersions are only thermodynamically stable for highly oxidized GO. These findings-validated against the extensive literature on GO systems in organic solvents-furnish quantitative explanations for the empirically unpredictable aggregation characteristics of GO and provide computational methods to design directed synthesis routes for diverse self-assemblies and applications.

8.
J Occup Environ Med ; 62(5): 350-358, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32080015

RESUMO

OBJECTIVE: This study evaluates the motivational processes between employee occupational safety and health climates and behaviors using the Theory of Self-Determination in a sample of diverse small businesses. METHODS: We used cross-sectional data to assess whether employee safety/health intrinsic, identified, and external motives mediate the relationship between safety/health climate and behavior. RESULTS: All three types of motivation mediated the relationship between safety and health climates and behaviors. CONCLUSION: Small businesses seeking to engage employees in Total Worker Health efforts should build strong safety and health climates because of their influence on employees' motivation to participate in health promoting and health protective programs.

9.
Health Phys ; 118(4): 427-437, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31985514

RESUMO

The radiation safety culture of those working in university open-source radioactive material laboratories was assessed by conducting both surveys and behavioral observations. Baseline results (n = 82, 89% response rate) of assessed safety culture categories indicated safety practices and safety compliance were the most in need of improvement. Specific training based on these results was provided to laboratory members at Princeton University, with creative signage and a safety newsletter posted in and around laboratories for reinforcement, in a targeted effort to improve the radiation safety culture. Signage posted utilized pop cultural memes and other engaging graphics designed to raise awareness of appropriate safety practices and the minimum laboratory attire expected while working in radioactive material laboratories. Postintervention results (n = 38, 43% response rate) indicated improvement in 4 out of the 10 safety culture indicators considered as well as fewer instances of improper safety practices. Collaborative techniques and increased communication between researchers and radiation safety staff appear to have initiated an improvement in the radiation safety culture in open-source radioactive material laboratories at Princeton University.


Assuntos
Laboratórios , Proteção Radiológica , Gestão da Segurança/métodos , Universidades , Humanos , Inquéritos e Questionários
10.
Nat Nanotechnol ; 15(2): 154-161, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31988506

RESUMO

Atherosclerosis is the process that underlies heart attack and stroke. A characteristic feature of the atherosclerotic plaque is the accumulation of apoptotic cells in the necrotic core. Prophagocytic antibody-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells; however, these therapies can cause off-target clearance of healthy tissues, which leads to toxicities such as anaemia. Here we developed a macrophage-specific nanotherapy based on single-walled carbon nanotubes loaded with a chemical inhibitor of the antiphagocytic CD47-SIRPα signalling axis. We demonstrate that these single-walled carbon nanotubes accumulate within the atherosclerotic plaque, reactivate lesional phagocytosis and reduce the plaque burden in atheroprone apolipoprotein-E-deficient mice without compromising safety, and thereby overcome a key translational barrier for this class of drugs. Single-cell RNA sequencing analysis reveals that prophagocytic single-walled carbon nanotubes decrease the expression of inflammatory genes linked to cytokine and chemokine pathways in lesional macrophages, which demonstrates the potential of 'Trojan horse' nanoparticles to prevent atherosclerotic cardiovascular disease.


Assuntos
Aterosclerose/metabolismo , Macrófagos , Nanotubos de Carbono , Fagocitose/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Animais , Antígeno CD47/metabolismo , Fármacos Cardiovasculares/química , Fármacos Cardiovasculares/farmacologia , Modelos Animais de Doenças , Feminino , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Masculino , Camundongos Transgênicos , Nanomedicina/métodos , Proteína Tirosina Fosfatase não Receptora Tipo 6/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Receptores Imunológicos/metabolismo
11.
J Safety Res ; 70: 181-191, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31847993

RESUMO

INTRODUCTION: Workplace accidents and injuries can be quite costly to both individual employees and their organizations. While safety climate (i.e., perceptions of policies and procedures related to safety that should reflect an organization's value of safety) has been established as a predictor of safety behaviors, less research has considered the possible negative pressures that could result from an environment that emphasizes safety. Though organizations may intend to create a positive safety climate, concerns about being treated differently if an employee were to be involved in a safety incident may result in unintended, but detrimental safety and health outcomes. METHOD: This study investigated the stigma associated with being involved in a safety-related incident in relation to self-reported safety behaviors and psychological health outcomes. The data were acquired through a two-wave prospective design, surveying workers from Amazon Mechanical Turk (MTurk; N = 528) who indicated they were exposed to at least one physical work stressor (e.g., heavy lifting; air quality; standing for extended periods) a few times each month or more. RESULTS: When controlling for safety climate, safety stigma was related to decreased safety compliance and poorer psychological health. There was a marginally significant interaction between safety stigma and safety motivation in relation to safety compliance. CONCLUSIONS: These findings suggest that experiencing pressure to work safely, for fear of being evaluated negatively, may actually come at the cost of employees' safety compliance and psychological health. Practical applications: These results may be useful in assessing and intervening to improve an organization's safety climate. Organizations should closely examine the climate for safety to ensure that positive aspects of safety are not undermined by a stigmatizing pressure associated with safety in the work environment.


Assuntos
Acidentes de Trabalho/psicologia , Gestão da Segurança/estatística & dados numéricos , Estigma Social , Local de Trabalho/psicologia , Acidentes de Trabalho/estatística & dados numéricos , Humanos , Estudos Prospectivos , Gestão da Segurança/normas , Autorrelato
12.
Nanomaterials (Basel) ; 9(11)2019 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-31717827

RESUMO

More than ever before, materials-driven product innovations in industry and shorter time-to-market introductions for new products require high advancement rates and a tight coupling between research, development and manufacturing [...].

14.
Sci Adv ; 5(8): eaaw3415, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31497642

RESUMO

Topological surface states (TSSs) in a topological insulator are expected to be able to produce a spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is conductive because it can completely suppress the TSSs, but it should be present if the ferromagnet is insulating. This study reports TSS-induced switching in a bilayer consisting of a topological insulator Bi2Se3 and an insulating ferromagnet BaFe12O19. A charge current in Bi2Se3 can switch the magnetization in BaFe12O19 up and down. When the magnetization is switched by a field, a current in Bi2Se3 can reduce the switching field by ~4000 Oe. The switching efficiency at 3 K is 300 times higher than at room temperature; it is ~30 times higher than in Pt/BaFe12O19. These strong effects originate from the presence of more pronounced TSSs at low temperatures due to enhanced surface conductivity and reduced bulk conductivity.

15.
Biomaterials ; 218: 119342, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31326657

RESUMO

The prognosis for glioblastoma (GBM) remains depressingly low. The biological barriers of the brain present a major challenge to achieving adequate drug concentrations for GBM therapy. To address this, we explore the potential of the nose-to-brain direct transport pathway to bypass the blood-brain barrier, and to enable targeted delivery of theranostic polyfunctional gold-iron oxide nanoparticles (polyGIONs) surface loaded with therapeutic miRNAs (miR-100 and antimiR-21) to GBMs in mice. These nanoformulations would thus allow presensitization of GBM cells to the systemically delivered chemotherapy drug temozolomide (TMZ), as well as in vivo multimodality molecular and anatomic imaging of nanoparticle delivery, trafficking, and treatment effects. First, we synthesized GIONs coated with ß-cyclodextrin-chitosan (CD-CS) hybrid polymer, and co-loaded with miR-100 and antimiR-21. Then we decorated their surface with PEG-T7 peptide using CD-adamantane host-guest chemistry. The resultant polyGIONs showed efficient miRNA loading with enhanced serum stability. We characterized them for particle size, PDI, polymer functionalization, charge and release using dynamic light scattering analysis, TEM and qRT-PCR. For in vivo intranasal delivery, we used U87-MG GBM cell-derived orthotopic xenograft models in mice. Intranasal delivery resulted in efficient accumulation of Cy5-miRNAs in mice treated with T7-targeted polyGIONs, as demonstrated by in vivo optical fluorescence and MR imaging. We measured the therapeutic response of these FLUC-EGFP labelled U87-MG GBMs using bioluminescence imaging. Overall, there was a significant increase in survival of mice co-treated with T7-polyGIONs loaded with miR-100/antimiR-21 plus systemic TMZ, compared to the untreated control group, or the animals receiving non-targeted polyGIONs-miR-100/antimiR-21, or TMZ alone. Once translated clinically, this novel theranostic nanoformulation and its associated intranasal delivery strategy will have a strong potential to potentiate the effects of TMZ treatment in GBM patients.


Assuntos
Compostos Férricos/química , Glioblastoma/tratamento farmacológico , Ouro/química , MicroRNAs/química , Temozolomida/uso terapêutico , Animais , Linhagem Celular Tumoral , Quitosana/química , Sistemas de Liberação de Medicamentos/métodos , Resistencia a Medicamentos Antineoplásicos , Humanos , Camundongos , Nanomedicina Teranóstica , Ensaios Antitumorais Modelo de Xenoenxerto , beta-Ciclodextrinas/química
16.
ACS Appl Mater Interfaces ; 11(30): 26863-26871, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31310093

RESUMO

With promising activity and stability for the oxygen reduction reaction (ORR), transition metal nitrides are an interesting class of non-platinum group catalysts for polymer electrolyte membrane fuel cells. Here, we report an active thin-film nickel nitride catalyst synthesized through a reactive sputtering method. In rotating disk electrode testing in a 0.1 M HClO4 electrolyte, the crystalline nickel nitride film achieved high activity and selectivity to four-electron ORR. It also exhibited good stability during 10 and 40 h chronoamperometry measurements in acid and alkaline electrolyte, respectively. A combined experiment-theory approach, with detailed ex situ materials characterization and density functional theory calculations, provides insight into the structure of the catalyst and its surface during catalysis. Design strategies for activity and stability improvement through alloying and nanostructuring are discussed.

17.
J Chem Inf Model ; 59(6): 2741-2745, 2019 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-31018633

RESUMO

Graphene oxide (GO) is an amorphous 2D material, which has found widespread use in the fields of chemistry, physics, and materials science due to its similarity to graphene with the benefit of being far easier to synthesize and process. However, the standard of GO characterization is very poor because its structure is irregular, being sensitive to the preparation method, and it has a propensity to transform due to its reactive nature. Atomistic simulations of GO are common, but the nanostructure in these simulations is often based on little evidence or thought. We have written a computer program to generate graphene oxide nanostructures for general purpose atomistic simulation based on theoretical and experimental evidence. The structures generated offer a significant improvement to the current standard of randomly placed oxidized functional groups and successfully recreate the two-phase nature of oxidized and unoxidized graphene domains observed in microscopy experiments. Using this model, we reveal new features of GO structure and predict that a critical point in the oxidation reaction exists as the oxidized region reaches a percolation threshold. Even by a conservative estimate, we show that, if the carbon to oxygen ratio is kept above 6, a continuous aromatic network will remain, preserving many of graphene's desirable properties, irrespective of the oxidation method or the size distribution of graphene sheets. This is an experimentally achievable degree of oxidation and should aid better GO synthesis for many applications.


Assuntos
Grafite/química , Nanoestruturas/química , Modelos Moleculares , Conformação Molecular
18.
ACS Nano ; 13(3): 2858-2869, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30714717

RESUMO

Nanoparticles' enhanced permeation and retention (EPR) variations due to tumor heterogeneity in naturally occurring brain tumors are commonly neglected in preclinical nanomedicine studies. Recent pathological studies have shown striking similarities between brain tumors in humans and dogs, indicating that canine brain tumors may be a valuable model to evaluate nanoparticles' EPR in this context. We recruited canine clinical cases with spontaneous brain tumors to investigate nanoparticles' EPR in different brain tumor pathologies using surface-enhanced Raman spectroscopy (SERS). We used gold nanoparticles due to their surface plasmon effect that enables their sensitive and microscopic resolution detection using the SERS technique. Raman microscopy of the resected tumors showed heterogeneous EPR of nanoparticles into oligodendrogliomas and meningiomas of different grades, without any detectable traces in necrotic parts of the tumors or normal brain. Raman observations were confirmed by scanning electron microscopy (SEM) and X-ray elemental analyses, which enabled localization of individual nanoparticles embedded in tumor tissues. Our results demonstrate nanoparticles' EPR and its variations in clinically relevant, spontaneous brain tumors. Such heterogeneities should be considered alongside routine preoperative imaging and histopathological analyses in order to accelerate clinical management of brain tumors using nanomedicine approaches.


Assuntos
Neoplasias Encefálicas/química , Neoplasias Encefálicas/diagnóstico por imagem , Nanomedicina , Nanopartículas/química , Animais , Análise Química do Sangue , Neoplasias Encefálicas/cirurgia , Cães , Ouro/química , Imagem por Ressonância Magnética , Tamanho da Partícula , Dióxido de Silício/química , Propriedades de Superfície
19.
Phys Chem Chem Phys ; 21(10): 5716-5722, 2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30801077

RESUMO

Mechanical exfoliation techniques are widely used to create high quality graphene samples for analytical use. Increasingly, mechanical methods are used to create large quantities of graphene, yet there is surprisingly little molecular insight into the mechanisms involved. We study the exfoliation of graphene with sticky tape using molecular dynamics. This is made possible by using a recently developed molecular dynamics forcefield, GraFF, to represent graphene's dispersion interactions. For nano-sized flakes we observe two different mechanisms depending on the polymer-adhesive used. A peeling mechanism which mixes shearing and normal mode exfoliation promotes synthesis of graphene rather than many-layered graphite. Armed with this new chemical insight we discuss the experimental methods that could preferentially produce graphene by mechanical exfoliation. We also introduce a mathematical model describing the repeated exfoliation of graphite.

20.
Cell Death Discov ; 4: 113, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30534421

RESUMO

Glioblastoma is the most common yet most lethal of primary brain cancers with a one-year post-diagnosis survival rate of 65% and a five-year survival rate of barely 5%. Recently the U.S. Food and Drug Administration approved a novel fourth approach (in addition to surgery, radiation therapy, and chemotherapy) to treating glioblastoma; namely, tumor treating fields (TTFields). TTFields involves the delivery of alternating electric fields to the tumor but its mechanisms of action are not fully understood. Current theories involve TTFields disrupting mitosis due to interference with proper mitotic spindle assembly. We show that TTFields also alters cellular membrane structure thus rendering it more permeant to chemotherapeutics. Increased membrane permeability through the imposition of TTFields was shown by several approaches. For example, increased permeability was indicated through increased bioluminescence with TTFields exposure or with the increased binding and ingress of membrane-associating reagents such as Dextran-FITC or ethidium D or with the demonstration by scanning electron microscopy of augmented number and sizes of holes on the cellular membrane. Further investigations showed that increases in bioluminescence and membrane hole production with TTFields exposure disappeared by 24 h after cessation of alternating electric fields thus demonstrating that this phenomenom is reversible. Preliminary investigations showed that TTFields did not induce membrane holes in normal human fibroblasts thus suggesting that the phenomenom was specific to cancer cells. With TTFields, we present evidence showing augmented membrane accessibility by compounds such as 5-aminolevulinic acid, a reagent used intraoperatively to delineate tumor from normal tissue in glioblastoma patients. In addition, this mechanism helps to explain previous reports of additive and synergistic effects between TTFields and other chemotherapies. These findings have implications for the design of combination therapies in glioblastoma and other cancers and may significantly alter standard of care strategies for these diseases.

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