The upscaling of zeolitic materials to technical catalysts implies the formulation of the active phase with additives that can affect catalytic performance. As an alternative, we herein present ...fibrillar ZrO2/HZSM-5 composites prepared by electrospinning where HZSM-5 zeolite aggregates are joint through inert ZrO2 fibers. For zeolite loadings of 5, 10 and 20 wt% and SiO2/Al2O3 ratios of 30, 50 and 80, well-dispersed zeolite aggregates smaller than 1.5 μm have been observed. The ZrO2/HZSM-5 composites were tested as catalysts in the dimethyl ether-to-olefins (DTO) process. The maximum olefin selectivity (ca. 70%) but fastest deactivation was observed for a zeolite loading of 5 wt%, with side reaction extent being promoted when increasing zeolite loading or density of acid sites. A comparison with a technical catalyst suggested that secondary reactions are limited due to the homogeneous distribution of the zeolite in the fibrillary material and to the higher accessibility of zeolite crystals.
Display omitted
•HZSM-5 aggregates are homogeneously distributed along ZrO2 fibers in the composite.•Accessibility to zeolite acid sites is not affected by zeolite loading or acid site density.•The ZrO2/HZSM-5 fibrillar composites show significant activity for the DTO process.•The ZrO2/HZSM-5 composites reduce side reactions compared to agglomerated catalysts.
This study examined longitudinal effects of adolescent and parent cultural stress on adolescent and parent emotional well‐being and health behaviors via trajectories of adolescent and parent family ...functioning. Recent immigrant Latino adolescents (Mage = 14.51) and parents (Mage = 41.09; N = 302) completed measures of these constructs. Latent growth modeling indicated that adolescent and parent family functioning remained stable over time. Early levels of family functioning predicted adolescent and parent outcomes. Baseline adolescent cultural stress predicted lower positive adolescent and parent family functioning. Latent class growth analyses produced a two‐class solution for family functioning. Adolescents and parents in the low family functioning class reported low family functioning over time. Adolescents and parents in the high family functioning class experienced increases in family functioning.
•No study have documented the predictors of ND among adolescent WP and cigarette smokers.•There were some commonalities and differences in predictors of ND milestones between WP and cigarette ...smokers.•Commonalities were the age of initiation and sibling tobacco use.•Differences were the role of physical activity and body mass index (BMI).•Smoking cessation interventions targeting youth should address modifiable and tobacco use-specific factors.
Identifying the factors associated with nicotine dependence (ND) is essential to prevent initiation and continued use, and to promote cessation among youth. This study aims to document the predictors of the appearance of initial ND symptoms and full ND syndrome among adolescent waterpipe (WP) and cigarette smokers.
A 6-year longitudinal study was conducted among 8th and 9th graders from 38 schools in Lebanon. The analysis sample included exclusive-WP (n = 228) and exclusive-cigarette smokers (n = 139). Weighted Cox proportional hazards models were used to characterizing predictors of initial ND symptoms and full ND syndrome.
Predictors of experiencing initial ND symptoms among WP smokers included low maternal educational level, having a sibling who smoked WP, low physical activity, high body mass index (BMI), smoking initiation at a younger age. For cigarette smokers these were being male, younger, having lower BMI, having a sibling who smoked cigarettes, living in a crowded household, and smoking daily. Among WP smokers, predictors of developing full ND syndrome include being younger, believing that WP smokers have more friends, depression, high levels of impulsivity, and initiating smoking at a younger age. For cigarette smokers, predictors of full ND syndrome were being younger and initiating smoking at a younger age.
Smoking cessation and prevention interventions targeting youth should address modifiable, and tobacco use-specific factors that influence the development of ND among young WP and cigarette smokers. They also need to start at a younger age to target those most vulnerable to developing life-long addiction to tobacco products.
Abstract This study examined longitudinal effects of cultural stress (a latent factor comprised of bicultural stress, ethnic discrimination, and negative context of reception) on depressive symptoms ...and a range of externalizing behaviors among recently (≤5 years in the U.S. at baseline) immigrated Hispanic adolescents. A sample of 302 adolescents (53% boys; mean age 14.51 years) completed baseline measures of perceived ethnic discrimination, bicultural stress, and perceived negative context of reception; and outcome measures of depressive symptoms, cigarette smoking, alcohol use, aggressive behavior, and rule-breaking behavior six months post-baseline. A path analysis indicated that higher cultural stress scores predicted higher levels of all outcomes. These effects were consistent across genders, but varied by study site. Specifically, higher cultural stress scores increased depressive symptoms among participants in Miami, but not in Los Angeles. Findings suggest that cultural stress is a clinically relevant predictor of depressive symptoms and externalizing behaviors among Hispanic immigrant adolescents.
Participating in a drinking game (DG) is common practice among university students and can increase students' risk for heavy drinking. Given the theoretical link between motivations to drink and ...alcohol use, careful consideration should be given to students' motivations to play DGs. In this study, we examined the factor structure, internal consistency, and concurrent validity of a revised version of the motives for playing drinking games (MPDG) scale, the MPDG-33.
University students (n = 3345, Mage = 19.77 years, SDage = 1.53; 68.8% = women; 59.6% = White) from 12 U.S. universities completed a confidential online self-report survey that included the MPDG-33 and questions regarding their frequency of DG participation and typical drink consumption while playing DGs.
Confirmatory factor analysis indicated the 7-factor model fit the data adequately, and all items had statistically significant factor loadings on their predicted factor. All subscales had adequate to excellent internal consistency and were positively correlated with the frequency of DG participation and the typical number of drinks consumed while playing DGs (though the correlations were small).
Findings suggest that the MPDG-33 can be reliably used in research and clinical settings to assess U.S. university students' motives for playing DGs.
Objective
The aims of this study are to investigate (1) how family response to acculturation (e.g., accusations of assimilation) is related to anxiety and depressive symptomatology for Latinx ...emerging adults. This study's goal is also to analyze (2) the extent to which ethnic identity components and gender moderate the respective associations.
Method
Cross‐sectional survey was completed by 200 Latinx emerging adults. Inclusion criteria involved reading English, ages 18–25, currently reside in Maricopa or Miami‐Dade Counties and self‐identify as Latinx. Analysis used hierarchical multiple regression and moderation analyses.
Results
Findings indicate that higher familial accusations of assimilation were associated with higher symptoms of depression and anxiety. Moderation analyses indicate that gender had a statistically significant interaction with accusations of assimilation in relation to symptoms of both depression and anxiety. A significant three‐way interaction between ethnic identity exploration, gender, and intracultural accusations of assimilation in relation to symptoms of depression interaction among men was found.
Conclusion
Findings from the study add to literature on the effect of intragroup marginalization on Latinx mental health and highlight gender differences. The ethnic identity component of exploration is found to be a protective factor for men which wanes over increasing levels of accusation of assimilation.
Many bridges and other structures worldwide present a lack of maintenance or a need for rehabilitation. The first step in the rehabilitation process is to perform a bridge inspection to know the ...bridge′s current state. Routine bridge inspections are usually based only on visual recognition. In this paper, a methodology for bridge inspections in communication routes using images acquired by unmanned aerial vehicle (UAV) flights is proposed. This provides access to the upper parts of the structure safely and without traffic disruptions. Then, a standardized and systematized novel image acquisition protocol is applied for data acquisition. Afterwards, the images are studied by civil engineers for damage identification and description. Then, specific structural inspection forms are completed using the acquired information. Recommendations about the need of new and more detailed inspections should be included at this stage when needed. The suggested methodology was tested on two railway bridges in France. Image acquisition of these structures was performed using an UAV for its ability to provide an expert assessment of the damage level. The main advantage of this method is that it makes it possible to safely accurately identify diverse damages in structures without the need for a specialised engineer to go to the site. Moreover, the videos can be watched by as many engineers as needed with no personal movement. The main objective of this work is to describe the systematized methodology for the development of bridge inspection tasks using a UAV system. According to this proposal, the in situ inspection by a specialised engineer is replaced by images and videos obtained from an UAV flight by a trained flight operator. To this aim, a systematized image/videos acquisition method is defined for the study of the morphology and typology of the structural elements of the inspected bridges. Additionally, specific inspection forms are proposed for every type of structural element. The recorded information will allow structural engineers to perform a postanalysis of the damage affecting the bridges and to evaluate the subsequent recommendations.
Polyacrylonitrile (PAN) is one of the materials most often used for carbonization. PAN nanofiber mats, created by electrospinning, are an especially interesting source to gain carbon nanofibers. A ...well-known problem in this process is fixing the PAN nanofiber mats during the stabilization process which is necessary to avoid contraction of the fibers, correlated with an undesired increase in the diameter and undesired bending. Fixing this issue typically results in breaks in the nanofiber mats if the tension is too high, or it is not strong enough to keep the fibers as straight as in the original state. This article suggests a novel method to overcome this problem by electrospinning on an aluminum substrate on which the nanofiber mat adheres rigidly, stabilizing the composite and carbonizing afterwards either with or without the aluminum substrate to gain either a pure carbon nanofiber mat or a metal/carbon composite.
Objective
Identifying and understanding determinants of alcohol use behavior among Hispanic immigrants is an increasingly significant public health concern. Although prior research has examined ...associations of cultural stressors with alcohol use among Hispanics, few studies have tested these associations among recent adult immigrants. As such, this study aimed to examine (a) the association of immigration stress on alcohol use severity among recently immigrated Hispanic adults (≤ 1 year in the United States) and (b) the moderating effects of gender, immigration status, and social support.
Method
A hierarchical multiple regression and moderation analyses were conducted on a sample of 527 participants in South Florida.
Results
Results indicated that, after controlling for demographic variables, preimmigration drinking behavior, and dimensions of social support, the association of higher immigration stress with higher alcohol use severity was statistically significant. Moderation analyses indicated that immigration stress had a statistically significant association with alcohol use severity among men, but not women. Also, dimensions of social support consistently reduced the deleterious effect of immigration stress on alcohol use severity.
Conclusion
This study adds to the scarce literature on cultural stressors and alcohol use among recent Hispanic immigrants. Findings suggest that it may be important to design gender‐specific interventions and that increasing levels of social support may offset the effects of immigration stress on alcohol use.
Hispanic emerging adults are often exposed to ethnic discrimination, yet little is known about coping resources that may mitigate the effects of ethnic discrimination on psychological stress in this ...rapidly growing population. As such, this study aims to examine (1) the associations of ethnic discrimination, distress tolerance, and optimism with psychological stress and (2) the moderating effects of distress tolerance and optimism on the association between ethnic discrimination and psychological stress. Data were drawn from a cross-sectional study of 200 Hispanic adults ages 18–25, recruited from two urban counties in Arizona and Florida. Hierarchical multiple regression and moderation analyses were utilized to examine these associations and moderated effects. Findings indicated that higher optimism was associated with lower psychological stress. Conversely, higher ethnic discrimination was associated with higher psychological stress. Moderation analyses indicated that both distress tolerance and optimism moderated the association between ethnic discrimination and psychological stress. These study findings add to the limited literature on ethnic discrimination among Hispanic emerging adults and suggest that distress tolerance may be a key intrapersonal factor that can protect Hispanic emerging adults against the psychological stress often resulting from ethnic discrimination.
PDF
