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1.
J Pain ; : 104574, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38788887

RESUMO

Social determinants of health play a key role in health disparities. Dysmenorrhea is a highly prevalent and impactful public health problem affecting reproductive-age females. Systematically examining social determinants of health (SDoH) in dysmenorrhea is important for identifying gaps in the literature and informing research, policy, and clinical practice to reduce the public health burden associated with dysmenorrhea. The purpose of this systematic review was to synthesize the literature on SDoH and dysmenorrhea. The review protocol was prospectively registered. We searched Medline, EMBASE, CINAHL, PsycINFO, Scopus, and Google Scholar through February 2024 using search strategies informed by the literature. Screening of the articles, data extraction, and risk-of-bias (RoB) assessment were conducted independently by at least 2 reviewers on the Covidence platform. Among 2,594 unique records screened, 166 met eligibility criteria and were included for data extraction and RoB assessment. Evidence suggests traumatic experiences, toxic environmental exposures, female genital mutilation, job-related stress, lack of menstrual education, and low social support were associated with worse dysmenorrhea outcomes. However, evidence was equivocal regarding the relationships between dysmenorrhea outcomes and SDoH factors, including socioeconomic status, geographical location, race/ethnicity, employment, and religion. Nearly all articles (99.4%) had a high or very high overall RoB. The relationships between SDoH and dysmenorrhea outcomes were often inconsistent and complicated by heterogeneous study populations and methodologies. More rigorous research examining SDoH in dysmenorrhea is needed to inform policy and clinical practice. PERSPECTIVE: This systematic review synthesizes evidence linking SDoH and dysmenorrhea. The relationships between SDoH and dysmenorrhea were often equivocal and complicated by heterogeneous study populations and methodologies. We identify directions for future research and SDoH factors that could be addressed clinically (eg, trauma, menstrual education, and occupational stress).

2.
Toxicol Sci ; 199(2): 172-193, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38547404

RESUMO

Formaldehyde is recognized as carcinogenic for the portal of entry sites, though conclusions are mixed regarding lymphohematopoietic (LHP) cancers. This systematic review assesses the likelihood of a causal relationship between formaldehyde and LHP cancers by integrating components recommended by NASEM. Four experimental rodent bioassays and 16 observational studies in humans were included following the implementation of the a priori protocol. All studies were assessed for risk of bias (RoB), and meta-analyses were conducted on epidemiological studies, followed by a structured assessment of causation based on GRADE and Bradford Hill. RoB analysis identified systemic limitations precluding confidence in the epidemiological evidence due to inadequate characterization of formaldehyde exposure and a failure to adequately adjust for confounders or effect modifiers, thus suggesting that effect estimates are likely to be impacted by systemic bias. Mixed findings were reported in individual studies; meta-analyses did not identify significant associations between formaldehyde inhalation (when measured as ever/never exposure) and LHP outcomes, with meta-SMRs ranging from 0.50 to 1.51, depending on LHP subtype. No associations with LHP-related lesions were reported in reliable animal bioassays. No biologically plausible explanation linking the inhalation of FA and LHP was identified, supported primarily by the lack of systemic distribution and in vivo genotoxicity. In conclusion, the inconsistent associations reported in a subset of the evidence were not considered causal when integrated with the totality of the epidemiological evidence, toxicological data, and considerations of biological plausibility. The impact of systemic biases identified herein could be quantitatively assessed to better inform causality and use in risk assessment.


Assuntos
Formaldeído , Exposição por Inalação , Formaldeído/toxicidade , Humanos , Animais , Exposição por Inalação/efeitos adversos , Neoplasias Hematológicas/induzido quimicamente , Neoplasias Hematológicas/epidemiologia , Medição de Risco , Carcinógenos/toxicidade
3.
PEC Innov ; 4: 100267, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38414869

RESUMO

Objective: Palliative care communication skills help tailor care to patients' goals. With a palliative care physician shortage, non-physicians must gain these serious illness communication skills. Historically, trainings have targeted physician-only groups; our goal was to train interprofessional teams. Methods: Workshops were conducted to teach palliative care communication skills and interprofessional communication. Participants completed surveys which included questions from the Interpersonal Reactivity Index, the Ekman Faces tool, the Consultation and Relational Empathy measure, open-ended questions about empathy, and measures of effective interprofessional practice. Results: Participants felt the workshop improved their ability to listen (p < 0.001), understand patients' concerns (p < 0.001), and show compassion (p = 0.008). It increased the perceived value of peer observation (p < 0.001) and ability to reflect (p = 0.02) during complex conversations. Different types of professionals adopted different communication goals, though all affirmed the importance of active listening. Participants felt they improved their ability to work within an interprofessional team. Conclusions: The course effectively trained 71 clinicians, the majority non-physicians, in serious illness communication and interprofessional team communication skills, and could be reproduced in similar settings. Innovation: We adapted an approach common to physician-only trainings to diverse interprofessional groups, added a team-based component using Applied Improvisation, and demonstrated its effectiveness.

4.
Small ; 20(5): e2304424, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37726235

RESUMO

Peptide assemblies are promising nanomaterials, with their properties and technological applications being highly hinged on their supramolecular architectures. Here, how changing the chirality of the terminal charged residues of an amphiphilic hexapeptide sequence Ac-I4 K2 -NH2 gives rise to distinct nanostructures and supramolecular handedness is reported. Microscopic imaging and neutron scattering measurements show thin nanofibrils, thick nanofibrils, and wide nanotubes self-assembled from four stereoisomers. Spectroscopic and solid-state nuclear magnetic resonance (NMR) analyses reveal that these isomeric peptides adopt similar anti-parallel ß-sheet secondary structures. Further theoretical calculations demonstrate that the chiral alterations of the two C-terminal lysine residues cause the formation of diverse single ß-strand conformations, and the final self-assembled nanostructures and handedness are determined by the twisting direction and degree of single ß-strands. This work not only lays a useful foundation for the fabrication of diverse peptide nanostructures by manipulating the chirality of specific residues but also provides a framework for predicting the supramolecular structures and handedness of peptide assemblies from single molecule conformations.


Assuntos
Lateralidade Funcional , Nanoestruturas , Peptídeos/química , Nanoestruturas/química , Isomerismo , Estrutura Secundária de Proteína
5.
Arch Womens Ment Health ; 26(6): 719-735, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37632569

RESUMO

Dysmenorrhea is characterized by pelvic pain associated with menstruation. Similar to people with other pain conditions, females who experience dysmenorrhea report increased psychological distress. However, the pooled magnitude of this association has not been quantified across studies. Accordingly, this meta-analytic review quantifies the magnitude of the associations between dysmenorrhea severity and psychological distress. We conducted a systematic search of the literature using PsycINFO, PubMed, CINHAL, Embase, and Web of Science. Analyzed studies provided observational data on dysmenorrhea severity and anxiety symptoms, depressive symptoms, and/or global psychological distress. A total of 44 studies were included, and three random-effects meta-analyses were conducted, with average pooled effect sizes calculated using Person's r. We found significant, positive associations between measures of dysmenorrhea severity and measures of depressive symptoms (r = 0.216), anxiety symptoms (r = 0.207), and global psychological distress (r = 0.311). Our review suggests that females with greater dysmenorrhea severity experience greater psychological distress. Future directions include defining a clinically meaningful dysmenorrhea severity threshold, understanding the mechanisms and directionality underlying the dysmenorrhea-psychological distress relationship, and designing and testing interventions to jointly address dysmenorrhea and psychological distress.


Assuntos
Dismenorreia , Angústia Psicológica , Feminino , Humanos , Dor Pélvica , Menstruação , Ansiedade
6.
J Phys Chem B ; 127(33): 7394-7407, 2023 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-37555779

RESUMO

By mixing ionic liquids (ILs), it is possible to fine-tune their bulk and interfacial structure. This alters their physical properties and solvation behavior and is a simple way to prepare a collection of ILs whose properties can be tuned to optimize a specific application. In this study, mixtures of perfluorinated and alkylated ILs have been prepared, and links between composition, properties, and nanostructure have been investigated. These different classes of ILs vary substantially in the flexibility and polarizability of their chains. Thus, a range of useful structural and physical property variations are accessible through mixing that will expand the library of IL mixtures available in an area that to this point has received relatively little attention. In the experiments presented herein, the physical properties and bulk structure of mixtures of 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM][Tf2N] and 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM-F13][Tf2N] have been prepared. The bulk liquid structure was investigated using a combination of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) experiments in combination with atomistic molecular dynamics simulations and the measurement of density and viscosity. We observed that the addition of [C8MIM-F13][Tf2N] to [C8MIM][Tf2N] causes changes in the nanostructure of the IL mixtures that are dependent on composition so that variation in the characteristic short-range correlations is observed as a function of composition. Thus, while the length scales associated with the apolar regions (polar non-polar peak─PNPP) increase with the proportion of [C8MIM-F13][Tf2N] in the mixtures, perhaps surprisingly given the greater volume of the fluorocarbon chains, the length scale of the charge-ordering peak decreases. Interestingly, consideration of the contact peak shows that its origins are both in the direct anion···cation contact length scale and the nature (and hence volume) of the chains appended to the imidazolium cation.

7.
Biomacromolecules ; 24(6): 2847-2855, 2023 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-37257089

RESUMO

Self-sorting in functionalized dipeptide systems can be driven by the chirality of a single amino acid, both at a high pH in the micellar state and at a low pH in the gel state. The structures formed are affected to some degree by the relative concentrations of each component showing the complexity of such an approach. The structures underpinning the gel network are predefined by the micellar structures at a high pH. Here, we describe the systems prepared from two dipeptide-based gelators that differ only by the chirality of one of the amino acids. We provide firm evidence for self-sorting in the micellar and gel phases using small-angle neutron scattering and cryo-transmission electron microscopy (cryo-TEM), showing that complete self-sorting occurs across a range of relative concentrations.


Assuntos
Dipeptídeos , Micelas , Dipeptídeos/química , Microscopia Eletrônica de Transmissão , Microscopia Crioeletrônica , Aminoácidos
8.
Pain Med ; 24(9): 1086-1099, 2023 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-37154693

RESUMO

Dysmenorrhea is pelvic pain associated with menstruation and is one of the most common pain conditions among reproductive-age women. It is commonly treated with medications, complementary and alternative medicine, and self-management techniques. However, there is increased focus on psychological interventions which modify thoughts, beliefs, emotions, and behavioral responses to dysmenorrhea. This review examined the efficacy of psychological interventions on dysmenorrhea pain severity and interference. We conducted a systematic search of the literature using PsycINFO, PubMed, CINHAL, and Embase. A total of 22 studies were included; 21 examined within-group improvement (ie, within-group analysis) and 14 examined between-group improvement (ie, between-group analysis). Random-effects meta-analyses were conducted on pain severity and interference, with average effect sizes calculated using Hedges's g. Within-group analyses showed decreased pain severity and interference at post-treatment (g = 0.986 and 0.949, respectively) and first follow-up (g = 1.239 and 0.842, respectively). Between-group analyses showed decreased pain severity at post-treatment (g = 0.909) and decreased pain severity and interference at first follow-up (g = 0.964 and 0.884, respectively) compared to control groups. This review supports the efficacy of psychological interventions for dysmenorrhea, but conclusions are tempered by suboptimal methodological quality of the included studies and high heterogeneity across studies. Additional, rigorous research is needed to determine the clinical utility of psychological interventions for dysmenorrhea.


Assuntos
Dismenorreia , Intervenção Psicossocial , Feminino , Humanos , Dismenorreia/terapia , Dor Pélvica
9.
ACS Nano ; 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36608273

RESUMO

The rational design of lipid nanoparticles (LNPs) for enhanced gene delivery remains challenging because of incomplete knowledge of their formulation-structure relationship that impacts their intracellular behavior and consequent function. Small-angle neutron scattering has been used in this work to investigate the structure of LNPs encapsulating plasmid DNA upon their acidification (from pH 7.4 to 4.0), as would be encountered during endocytosis. The results revealed the acidification-induced structure evolution (AISE) of the LNPs on different dimension scales, involving protonation of the ionizable lipid, volume expansion and redistribution of aqueous and lipid components. A similarity analysis using an LNP's structural feature space showed a strong positive correlation between function (measured by intracellular luciferase expression) and the extent of AISE, which was further enhanced by the fraction of unsaturated helper lipid. Our findings reveal molecular and nanoscale changes occurring during AISE that underpin the LNPs' formulation-nanostructure-function relationship, aiding the rational design of application-directed gene delivery vehicles.

10.
Curr Opin Psychol ; 49: 101510, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36459929
11.
J Am Chem Soc ; 144(47): 21544-21554, 2022 11 30.
Artigo em Inglês | MEDLINE | ID: mdl-36345816

RESUMO

Peptide self-assembly is a hierarchical process during which secondary structures formed in the initial stages play a critical role in determining the subsequent assembling processes and final structural ordering. Unusual secondary structures hold promise as a source to develop novel supramolecular architectures with unique properties. In this work, we report the design of a new peptide self-assembly strategy based on unusual α-sheet secondary structures. In light of the strong propensity of leucine toward forming helical conformations and its high hydrophobicity, we design two short amphiphilic peptides Ac-LDLLDLK-NH2 and Ac-DLLDLLDK-NH2 with alternating l- and d-form amino acids. Microscopic imaging, neutron scattering, and spectroscopic measurements indicate that the two heterochiral peptides form highly ordered wide nanotubes and helical ribbons with monolayer thickness, in sharp contrast to twisted nanofibrils formed by the homochiral peptide Ac-LLLLK-NH2. Molecular dynamics simulations from monomers to trimers reveal that the two heteropeptides fold into α-sheets instead of ß-sheets, which readily pack into tubular architectures in oligomer simulations. Simulated circular dichroism spectra based on α-sheet oligomers validate the proposed α-sheet secondary structures. These results form an important basis for the rational design of higher-order peptide assemblies with novel properties based on unusual α-sheet secondary structures.


Assuntos
Aminoácidos , Peptídeos , Peptídeos/química , Estrutura Secundária de Proteína , Dicroísmo Circular , Conformação Proteica em Folha beta
12.
3D Print Med ; 8(1): 34, 2022 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-36371509

RESUMO

BACKGROUND: Like most hospitals, our hospital experienced COVID-19 pandemic-related supply chain shortages. Our additive manufacturing lab's capacity to offset these shortages was soon overwhelmed, leading to a need to improve the efficiency of our existing workflow. We undertook a work system analysis guided by the Systems Engineering Initiative for Patient Safety (SEIPS) construct which is based on human factors and quality improvement principles. Our objective was to understand the inefficiencies in project submission, review, and acceptance decisions, and make systematic improvements to optimize lab operations. METHODS: Contextual inquiry (interviews and workflow analysis) revealed suboptimal characteristics of the system, specifically, reliance on a single person to facilitate work and, at times, fractured communication with project sponsors, with root causes related to the project intake and evaluation process as identified through SEIPS tools. As interventions, the analysis led us to: 1) enhance an existing but underused project submission form, 2) design and implement an internal project scorecard to standardize evaluation of requests, and 3) distribute the responsibility of submission evaluation across lab members. We implemented these interventions in May 2021 for new projects and compare them to our baseline February 1, 2018 through - April 30, 2021 performance (1184 days). RESULTS: All project requests were submitted using the enhanced project submission form and all received a standardized evaluation with the project scorecard. Prior to interventions, we completed 35/79 (44%) of projects, compared to 12/20 (60%) of projects after interventions were implemented. Time to review new submissions was reduced from an average of 58 days to 4 days. A more distributed team responsibility structure permitted improved workflow with no increase in staffing, allowing the Lab Manager to devote more time to engineering rather than administrative/decision tasks. CONCLUSIONS: By optimizing our workflows utilizing a human factors approach, we improved the work system of our additive manufacturing lab to be responsive to the urgent needs of the pandemic. The current workflow provides insights for labs aiming to meet the growing demand for point-of-care manufacturing.

13.
Langmuir ; 38(39): 11845-11859, 2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-36121768

RESUMO

We report the synthesis of a new conjugated polymer bearing crown ether moieties, poly[(N(1-aza-[18]crown-6)carbamido)thiophene-2,5-diyl-alt-1,4-phenylene] (BG2). In water, BG2 forms a dispersion with a slightly cloudy appearance. We have studied the effect of adding surfactants, with different polar head groups, on these polymer-polymer aggregates. Special attention is given to the system with the anionic surfactant, sodium dodecyl sulfate (SDS). The combination of photophysical techniques with electrical conductivity, NMR (1H, 13C, and 27Na), DFT calculations, molecular dynamics simulations, and small-angle neutron scattering (SANS) provides a detailed picture on the behavior of the SDS/BG2 system in aqueous solution and in thin films. NMR, electric conductivity, and DFT results suggest that hydrophilic interactions occur between the polar headgroup of the surfactant (OSO3- Na+) and the aza-[18]-crown-6 moiety. DFT calculations confirmed the capability of BG2 to form stable complexes with the Na+ cations, where the cation can be either inside the azacrown cavity or sandwiched between the cavity and the polymer chain, which seem to determine the position of the surfactant hydrocarbon chain and, therefore, be responsible for the disruption of the BG2 aggregates and subsequent increase in the photoluminescence quantum yields. SANS measurements, made with hydrogenated and deuterated SDS in D2O, clearly show how micron-sized aggregates of BG2 are broken down by SDS and then how BG2 becomes preferentially incorporated within joint colloidal particles of BG2 and SDS with increasing [SDS]/[BG2] molar ratio.

14.
J Appl Crystallogr ; 55(Pt 4): 966-977, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35974738

RESUMO

A general method to invert parameter distributions of a polydisperse system using data acquired from a small-angle scattering (SAS) experiment is presented. The forward problem, i.e. calculating the scattering intensity given the distributions of any causal parameters of a theoretical model, is generalized as a multi-linear map, characterized by a high-dimensional Green tensor that represents the complete scattering physics. The inverse problem, i.e. finding the maximum-likelihood estimation of the parameter distributions (in free form) given the scattering intensity (either a curve or an image) acquired from an experiment, is formulated as a constrained nonlinear programming (NLP) problem. This NLP problem is solved with high accuracy and efficiency via several theoretical and computational enhancements, such as an automatic data scaling for accuracy preservation and GPU acceleration for large-scale multi-parameter systems. Six numerical examples are presented, including both synthetic tests and solutions to real neutron and X-ray data sets, where the method is compared with several existing methods in terms of their generality, accuracy and computational cost. These examples show that SAS inversion is subject to a high degree of non-uniqueness of solution or structural ambiguity. With an ultra-high accuracy, the method can yield a series of near-optimal solutions that fit data to different acceptable levels.

15.
Phys Chem Chem Phys ; 24(26): 15811-15823, 2022 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-35762383

RESUMO

The preparation of mixtures of ionic liquids (ILs) represents an attractive strategy to tune their properties, an important aspect of which is to understand how the structure of the bulk varies with composition. In this study, small-angle neutron scattering (SANS) was used to probe mixtures of methylimidazolium-based ionic liquids [Cnmim][Tf2N] with [C2mim][Tf2N]) (n = 4, 6, 8 and 10) and of [Cmmim][Tf2N] with [C12mim][Tf2N] (m = 2, 4, 6 and 8). Mixtures were prepared in both contrasts, which is to say that one component would be fully hydrogenated while the other was fully deuterated, and vice versa. Data were fitted using a range of appropriate models, of which the Teubner-Strey model provided most useful information and the pure materials showed a nascent Polar Non-polar Peak (PNPP) for n = 6, which became more evident as n increased. In the mixtures [Cnmim]x[C2mim]1-x[Tf2N], the PNPP was evident for n = 10 and 8, nascent for n = 6 and absent for n = 4, with percolation showing a very strong dependence on the chain length of the added IL, [Cnmim][Tf2N]. In contrast, while the ability of [C12mim][Tf2N] to form percolated structures was damped when mixed with [Cmmim][Tf2N], as m increased from 2 to 6, this effect was less strong. However, data obtained for mixtures of [C12mim][Tf2N] and [C8mim][Tf2N], both of which percolate as pure materials, did not fit easily in any of the models applied to the previous systems and gave results that depended on the contrast used. Complementary small-angle X-ray scattering (SAXS) data, however, showed the expected evolution and behaviour of the PNPP, COP and CP, revealing that the unexpected observations were due to an adventitious matching out of isotopic contrasts. As well as revealing details of the structures of these IL mixtures, the results also point to complementary strategies for generating bulk percolated structures as a function of cation chain length.

17.
Front Hum Neurosci ; 16: 809905, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35496064

RESUMO

Introduction: Cognitive impairment is a highly prevalent non-motor feature of Parkinson's disease (PD). A better understanding of the underlying pathophysiology may help in identifying therapeutic targets to prevent or treat dementia. This study sought to identify metabolic alterations in the prefrontal cortex (PFC), a key region for cognitive functioning that has been implicated in cognitive dysfunction in PD. Methods: Proton Magnetic Resonance Spectroscopy was used to investigate metabolic changes in the PFC of a cohort of cognitively normal individuals without PD (CTL), as well as PD participants with either normal cognition (PD-NC), mild cognitive impairment (PD-MCI), or dementia (PDD). Ratios to Creatine (Cre) resonance were obtained for glutamate (Glu), glutamine and glutamate combined (Glx), N-acetylaspartate (NAA), myoinositol (mI), and total choline (Cho), and correlated with cognitive scores across multiple domains (executive function, learning and memory, language, attention, visuospatial function, and global cognition) administered to the PD participants only. Results: When individuals retain cognitive capabilities, the presence of Parkinson's disease does not create metabolic disturbances in the PFC. However, when cognitive symptoms are present, PFC Glu/Cre ratios decrease with significant differences between the PD-NC and PPD groups. In addition, Glu/Cre ratios and memory scores were marginally associated, but not after Bonferroni correction. Conclusion: These preliminary findings indicate that fluctuations in prefrontal glutamate may constitute a biomarker for the progression of cognitive impairments in PD. We caution for larger MRS investigations of carefully defined PD groups.

18.
J Colloid Interface Sci ; 620: 346-355, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35429712

RESUMO

HYPOTHESIS: As compared to common aliphatic surfactants, increasing the number of pendant or incorporated aromatic groups in a surfactant is expected to offer significant enhancement in the affinity for graphene surfaces. The basis for enhanced graphene-philicity of aromatic surfactants is that they can develop appreciable π - π interactions with graphene. Furthermore, charged (anionic) surfactants are expected to confer electrostatic stabilization on surfactant-graphene composites. Hence, it is expected that anionic aromatic surfactants combine these two properties for effective stabilization of graphene dispersions in water. EXPERIMENTAL: The properties of two custom made graphene-compatible surfactants carrying two and three aromatic moieties in the hydrophobic tails, namely DC3Ph2 (sodium 1,4-dioxo-1,4-bis(3-phenylpropoxy)butane-2-sulfonate) and TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate) were compared with other common ionic commercial surfactants. Air-water (a/w) surface tension measurements were used to assess the surfactant adsorption and interfacial packing in the absence and presence of graphene. The surfactant coverage index for graphene (Ф) was calculated using surfactant headgroup areas derived from a/w surface tension data, chain volumes, and molecular fragment volumes from literature. FINDINGS: Increasing the number of aromatic groups and tails per surfactant was shown to increase the ability of surfactants to pack and fill space, as expressed by Ф. Comparison between the values of Ф for surfactants of different chain structure and architecture showed that the affinity for graphene increased with Ф. Hence, there is an implicit link between surfactant-graphene compatibility and the identity, chemical composition and architecture of the surfactant chains.


Assuntos
Grafite , Tensoativos , Sódio , Tensão Superficial , Tensoativos/química , Água/química
19.
J Colloid Interface Sci ; 618: 78-87, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35334364

RESUMO

HYPOTHESIS: Nonionic alkyl ethoxylate surfactants are widely used in agrochemicals to facilitate the permeation of systemic herbicides and fungicides across the plant waxy film. Industrial grade surfactants are often highly mixed and how the mixing affects their interactions with pesticides and wax films remains largely unexplored. A better understanding could enable design of mixed nonionic surfactants for herbicides and fungicides to maximize their efficiency and reduce wastage whilst controlling their impact on plant wax films. EXPERIMENT: In this study, nonionic surfactants with general structure n-oxyethylene glycol monododecyl ether (C12En) were used to form surfactant mixtures with the same average ethoxylate numbers but different hydrophilic-lipophilic balance (HLB) values. Their mixed micellar systems were then used to solubilize a herbicide diuron (DN) and a fungicide cyprodinil (CP), followed by plant wax solubilization upon contact with wax films. These processes were monitored by 1H NMR and SANS. FINDING: Pesticide solubilization made surfactant micelles effectively more hydrophobic but subsequent wax dissolution caused pesticide release and the restoration of the micellar amphiphilicity. Nonionic surfactants with lower HLBs form larger nanoaggregates, show enhanced wettability, and have better ability to solubilize and permeate pesticides across the wax film, but may cause significant damage to plant growth. These observations help explain why herbicides applied on weeds would benefit from surfactants with lower HLB values while fungicides require surfactants with HLBs to balance between delivery efficiency and potential phytotoxicity risks.


Assuntos
Fungicidas Industriais , Herbicidas , Praguicidas , Herbicidas/química , Micelas , Praguicidas/química , Solubilidade , Tensoativos/química , Ceras
20.
J Am Coll Health ; : 1-12, 2022 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-35298356

RESUMO

OBJECTIVE: The COVID-19 pandemic has disrupted people's lives around the world, including college students. This cross-sectional study aimed to 1) describe psychological distress, coping, and expectancies of undergraduates during COVID-19 "stay-at-home" orders and 2) examine the associations among these variables. PARTICIPANTS AND METHODS: Midwestern US undergraduates (N = 186) completed measures of psychological distress, coping behaviors, and expectancies in March-April 2020 during the initial round of "stay-at-home" orders. RESULTS: Students engaged in approach coping and disease prevention behaviors and had low expectations for contracting COVID-19. Most students reported clinically significant depression or anxiety. Adherence to disease prevention behaviors was associated with less stress but more anxiety. Positive expectancies and approach coping were associated with less distress. Avoidance coping was associated with more distress. CONCLUSIONS: This study describes the toll that COVID-19 has had on college students. Continued attention to the mental health of college students during the pandemic is imperative.

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