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Open access

Fatima Hossain and Nuno Ferreira

Abstract

Objectives

Self-concept distortion has been extensively linked with decreasing mental health in gay and lesbian youth. Social context has been proposed to have a moderating effect on the development of a healthy self-concept. However, no good quality review has approached these concepts with regards to LGBT youth.

Methods

A systematic review was conducted on the relationship between social context and self-concept in gay and lesbian youth. Twenty studies were included in the review.

Results

Quality assessment of papers yielded moderate methodological strength. Findings implied that social context has considerable influence on self-concept development. Discrepancies in assessment methods, areas of social context examined, and one-dimensional nature of examining self-concept interferes with drawing explicit conclusions regarding the relationship between social context and self-concept.

Conclusion

Positivity of social context is not conclusively relatable to positive self-concept development, and similarly, a negative context is not predetermining of self-concept distortions. Building on resilience factors of gay and lesbian youth, working together with families, and advancing and utilizing available educational and community resources should mitigate the strength of overt and covert heterosexism hindering healthy self-concept development. Further longitudinal and cross-cultural research will be necessary to provide insight into the mechanisms of associations.

Open access

Shalu Choudhary and Sunil

Abstract

We show that the global non-linear stability threshold for convection in a double-diffusive couple-stress fluid saturating a porous medium is exactly the same as the linear instability boundary. The optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. It is also found that couple-stress fluid saturating a porous medium is thermally more stable than the ordinary viscous fluid, and the effects of couple-stress parameter (F ) , solute gradient ( S f ) and Brinkman number ( D a ) on the onset of convection is also analyzed.

Open access

Abdelmadjid Abdi, Khelifa Abbeche, Djamel Athmania and Mounir Bouassida

Abstract

This paper presents the results obtained from an experimental programme and numerical investigations conducted on model tests of strip footing resting on reinforced and unreinforced sand slopes. The study focused on the determination of ultimate bearing capacity of strip footing subjected to eccentric load located either towards or opposite to the slope facing. Strip footing models were tested under different eccentricities of vertical load. The obtained results from tests conducted on unreinforced sand slope showed that the increase in eccentricity of applied load towards the slope facing decreases the ultimate bearing capacity of footing. Predictions of the ultimate bearing capacity obtained by the effective width rule are in good agreement with those proposed from the consideration of total width of footing subjected to eccentric load. The ultimate bearing capacity of an eccentrically loaded footing on a reinforced sand slope can be derived from that of axially loaded footing resting on horizontal sand ground when adopting the effective width rule and the coefficient of reduction due to the slope. When increasing the distance between the footing border to the slope crest, for unreinforced and reinforced ground slope by geogrids, the ultimate bearing capacity of footing is no more affected by the slope ground.

Open access

Agata Józefiak, Silvia Nogales-Mérida, Zuzanna Mikołajczak, Mateusz Rawski, Bartosz Kierończyk and Jan Mazurkiewicz

Abstract

A 71–day–long experiment was conducted to evaluate the inclusion of 20% Hermetia illucens (HI) meal; Tenebrio molitor (TM) meal; Gryllodes sigillatus (GS) meal; and Blatta lateralis (BL) meal in comparison to a control diet without any insect-based materials that used fish meal as the main source of protein. A total of 1950 rainbow trout juveniles (53.39 ± 3.74 g) were used. The formulated diets were isonitrogenous (45%) and isoenergetic (10 MJ kg-1). The inclusion of a full-fat insect meal did not affect the survival rate during the experimental period. The growth performance was significantly improved in the BL and TM treatments, while in the HI treatment was not affected. However, the GS treatment had a negative effect on the growth performance. The villus height decreased in the TM and GS treatment groups and increased in the BL diet group. The total number of bacteria increased in all insect meal diet groups. The results of the experiment show that B. lateralis, T. molitor and H. illucens full-fat meals can be used as a partial fish meal replacement without negative effects on survival or growth performance parameters. Moreover, full-fat insect meals may be considered as a protein source and a functional feed component that may positively affect the histomorphological structure of the fish gastrointestinal tract and stimulate the expansion of beneficial bacterial populations in the gut.

Open access

Moataz Fathi, Magdy Abdelsalam, Ibrahim Al-Homidan, Tarek Ebeid, Mohamed Shehab-El-Deen, Mohamed Abd El-Razik, Osama Abou-Emera and Mohamed Mostafa

Abstract

This research aimed to study the effect of dietary eucalyptus (Eucalyptus camaldulensis) leaves powder (EL) on growth performance, blood parameters, immune response and caecal microbiota in 84 growing Jabali and V-Line rabbits raised under high environmental temperature. The experiment started at 10 weeks of age and lasted 6 weeks. Rabbits were randomly distributed into three dietary eucalyptus treatments; control (no EL) and two supplemented groups with 0.1% and 0.2% EL powder. Rabbits were weighed at the beginning and at the end of the experiment. Feed intake, weight gain and feed conversion ratio were determined. Cell-mediated immune response was evaluated. At the end of the experiment, 54 rabbits were slaughtered (nine rabbits/sub-group). The results showed that the high level of EL (0.2%) had a negative effect on growth performance, dressing%, mid part% and significantly increased cell mediated response. Rabbits fed the high level of EL showed shortening in caecum length. Significant linear reduction of total bacterial count and E. coli was observed in both groups given either 0.1% or 0.2% EL compared to the control group. Similar trend was found in the percentage of Salmonella sp detection in both breeds. Jabali rabbits were significantly heavier than V-line rabbits and had better FCR and carcass traits except for fore part %. Additionally, they showed lower total microbial count. The current study indicated that EL could be utilized as an effective feed additive to improve cellular immunity and to reduce caecal bacterial counts in rabbits raised under high ambient temperature.

Open access

Chenchen Han, Weidong Gao and Lifen Chen

Abstract

During the air flow twisting process of jet vortex spinning, the moving characteristics of flexible free-end fiber are complex. In this paper, the finite element model of the fiber is established based on elastic thin rod element. According to the air pressure and velocity distribution in the airflow twisting chamber of jet vortex spinning, this paper analyzes the undetermined coefficients of the finite element kinetic differential equation of the free-end fiber following the principle of mechanical equilibrium, energy conservation, mass conservation and momentum conservation. Based on numerical simulation, this paper gets the trajectory of the free-end fiber. Finally, the theoretical result of the free-end fiber trajectory by finite element simulating is tested by an experimental method. This paper has proposed a new method to study the movement of the fiber and learn about the process and principle of jet vortex spinning.

Open access

Feichao Zhu, Bin Yu, Juanjuan Su and Jian Han

Abstract

With aim to improve the mechanical and thermal properties of poly (lactic acid) (PLA) melt-blown nonwovens (MBs), polyamide 11 (PA11) was melt blended with PLA at the weight proportions of PLA/PA11 (95/5, 90/10, 85/15, 80/20), and the corresponding PLA/PA11 MBs were also manufactured. The crystallization, thermal and rheological behaviors of PLA/PA11 blends were investigated. PLA/PA11 MBs were also characterized by morphology and mechanical properties. The results indicated that PA11, as globular dispersed phases, formed confined crystals and could improve the thermal stability of PLA matrix. The viscosity of PLA/PA11 blends was slightly increased but the rheological behaviors of “shear-thinning” kept unchanged in comparison with PLA. The average diameter of PLA/PA11 MB fibers was slightly increased, whereas the toughness of PLA/PA11 MBs including the strength and elongation were efficiently enhanced compared with those of PLA MBs.

Open access

Grzegorz Szparaga, Magdalena Brzezińska, Ewelina Pabjańczyk-Wlazło, Michał Puchalski, Sławomir Sztajnowski and Izabella Krucińska

Abstract

The results of studies assessing the influence of the addition of carbon nanofillers, such as multiwalled carbon nanotubes (MWCNTs) and graphene oxide (GO) that differ in size and structure, on the molecular and supramolecular structure and properties of alginate fibers that might be prospective precursors for carbon fiber (PCF) industry are presented in this article. The investigation was carried out by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), and tension testing. In the frame of the current study, two types of alginate fibers were examined and compared: alginic acid and calcium alginate fibers. Alginic acid fibers were formed by chemical treatment of calcium alginate fibers with hydrochloric acid due to the fact that Ca2+ ions presented in the fibers were expected to adversely affect the prospective carbonization process. This investigation brought important conclusions about the influence of nanofillers on the physical properties of the final material. Understanding the link between the incorporation of carbon nanostructures and a possible influence on the formation of ordered carbon structures in the precursor fibers brings an important opportunity to get insights into the application of alginate fibers as a prospective base material for obtaining cost-efficient carbon fibers.

Open access

Nithyaprakash Venkatasamy and Saravanan Dhandapani

Abstract

Garment cling fit is a proximal fit that emphasizes close clinging contour lines of the apparel maintained by it on the human body in regular postures and while performing primary movements. To understand the nature of interface between ease reduction treatments and structural constructs, three-dimensional (3D) modeling of human body using body mapping concept and ease reduction treatment’s role in explaining the garment strain patterns in cling fit conditions were investigated. We report the impact of ease reduction treatment that defines the proportions and measurements of the cling fit pattern with reference to human body surface profile.

Open access

Deniz Mutlu Ala and Gamze Gülşen Bakıcı

Abstract

Needle penetration force (NPF) is one of the main factors, which is used to determine fabric sewability. In this study, it was aimed to investigate sewability (based on NPF) of 1 × 1 rib knitted fabrics, which were produced by the separate ends of yarns. 18 types of fabrics were knitted with Ne 30/1 yarns with variations of stitch density and number of separate ends, whereas the other parameters were constant. Sewability tests were applied to fabrics after pretreatment and relaxation procedures by using the L&M sewability tester. As a result, it was seen that the number of separate ends and the stitch density have influence on the needle penetration values of 1 × 1 rib knitted fabrics.