How diverse are the samples used to study intimate relationships? A systematic review.

The social and behavioral sciences have long suffered from a lack of diversity in the samples used to study a broad array of phenomena. In an attempt to move toward a more contextually-informed approach, multiple subfields have undertaken meta-science studies of the diversity and inclusion of underrepresented groups in their body of literature. The current study is a systematic review of the field of relationship science aimed at examining the state of diversity and inclusion in this field. Relationship-focused papers published in five top relationship science journals from 2014-2018 (N = 559 articles, containing 771 unique studies) were reviewed. Studies were coded for research methods (e.g., sample source, dyadic data, observational data, experimental design) and sample characteristics (e.g., age, education, income, race/ethnicity, sexual orientation). Results indicate that the modal participant in a study of romantic relationships is 30 years old, White, American, middle-class, college educated, and involved in a different-sex, same-race relationship. Additionally, only 74 studies (10%) focused on traditionally underrepresented groups (i.e., non-White, low-income, and/or sexual and gender minorities). Findings underscore the need for greater inclusion of underrepresented groups to ensure the validity and credibility of relationship science. We conclude with general recommendations for the field.

Utilization of Agave durangensis leaves by Bacillus cereus 4N for polyhydroxybutyrate (PHB) biosynthesis.

Lignocellulosic wastes may provide a means to economize polyhydroxybutyrate (PHB) production. This study has proposed the use of Agave durangensis leaves obtained from the artisanal mezcal industry as a novel substrate for this aim. Results revealed an increase in PHB biosynthesis (0.32 g/L) and improvement in %PHB (16.79-19.51%) by Bacillus cereus 4N when A. durangensis leaves used as carbon source were physically pre-treated by ultrasound for 30 min (ADL + US30') and thermally pre-treated (ADL + Q). Chemical analyses and SEM studies revealed compositional and morphological changes when A. durangensis leaves were physically pre-treated. Also, elemental analysis of growth media showed that carbon/nitrogen ratios of 14-21, and low nitrogen, hydrogen, and protein content were well-suited for PHB biosynthesis. Confocal microscopy revealed morphological changes in the bacterial cell and carbonosome structure under the influence of different substrates. Finally, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analyses showed that homopolymeric PHB with a high thermal-resistance (271.94-272.89 °C) was produced. Therefore, the present study demonstrates the potential use of physically pre-treated A. durangensis leaves to produce PHB. These results promote the development of a circular economy in Mexico, where lignocellulosic wastes can be employed to produce value-added biotechnological products.

Electrospun Polyvinylpyrrolidone-Gelatin and Cellulose Acetate Bi-Layer Scaffold Loaded with Gentamicin as Possible Wound Dressing.

Acceleration of wound healing can be achieved with the use of wound dressings. Through the electrospinning technique, a polymeric scaffold composed of two layers was processed: a gelatin and polyvinylpyrrolidone layer with gentamicin, and a second layer of cellulose acetate. The conditions for the electrospinning process were standardized for voltage parameters, feed flow and the distance from the injector to the collector. Once the values of the main variables for the electrospinning were optimized, a three-hour processing time was established to allow the separation of the material from the collector. The obtained material was characterized by observations on scanning electron microscopy, Fourier transform infrared spectroscopy and thermal analysis; contact angle measurement was performed to evaluate wettability properties, and antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus were evaluated using the Kirby-Bauer test. The obtained fibers that form the bi-layer scaffold present diameters from 100 to 300 nm. The scaffold presents chemical composition, thermal stability, wettability characteristics and antibacterial activity that fulfill the proposal from this study, based on obtaining a scaffold that could be used as a drug delivery vehicle and a wound dressing material.

Efficient recovery of thermostable polyhydroxybutyrate (PHB) by a rapid and solvent-free extraction protocol assisted by ultrasound.

Nowadays, there are great research interest in polyhydroxybutyrate (PHB) recovery protocols that reduce the use of organic solvents and efficiently recover this bacterial biopolymer. The present study reports an extraction protocol assisted by ultrasound, which is a rapid protocol that increases the amount of polymeric matter extracted, reduces the cellular digestion step with sodium hypochlorite and eliminates the use of organic solvents. Likewise, characterization studies by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) demonstrated that the biopolymer recovered by this protocol is PHB homopolymer with a major thermal-resistance and crystalline properties. Besides, in this study are reported the thermic and crystalline differences between the PHB obtained from the fermentation of complex carbohydrates (agavins) and simple sugars. The biopolymer obtained by this rapid extraction protocol would be suitable for ecological and biomedical applications, due to the low melting temperature, less than 50% crystallinity, and the lack of lipopolysaccharides. Therefore, this extraction protocol might represent an alternative to the traditional protocol based on NaOCl-chloroform and is part of the green trend to improve the PHB production.

Cr(VI) adsorption from aqueous solution by fungal bioremediation based using Rhizopus sp.

The highly toxic species of Chromium in its hexavalent state is an important hazard to the flora and fauna, causing a rupture in balance especially in aquatic environments. The removal of Cr(VI) ions from aqueous solutions using fungal biomass of Rhizopus sp. was investigated under batch experiments. The biomass was produced and treated with NaCl to compare pre-treated and untreated biosorbents capacity. Adsorption of Cr(VI) was investigated with a 23 experimental design to determine the best operational parameters including pH [2.0-4.0], temperature [20-40 °C] and agitation [50-150 rpm]. Maximum Cr(VI) uptake (99%) indicated that pH 2.0 is the optimal for Cr(VI) removal. Linear and non-linear kinetic models were evaluated. The best fitting for linear kinetics was the pseudo-second order linear equation and the Elovich model in its non-linear form, suggesting chemisorption as the controlling step of adsorption. Results followed Langmuir isotherm equation, the qm was 9.95 (mg·g-1) for Rhizopus sp. + NaCl. Thermodynamic parameters were calculated using the adsorption equilibrium constant obtained from Langmuir isotherm and indicated that the adsorption process was spontaneous and endothermic. The surface characteristics of the biomass were analyzed by Fourier transform infrared (FTIR) spectra; the analysis showed the involvement of amino groups in the bonding with Cr(VI). SEM and EDX analysis confirmed the presence of Cr in the biomass after adsorption. The results of these experiments may be utilized for modeling, simulation, and scale-up processes in the future.

Biosorption of lead (II) and cadmium (II) using Escherichia coli genetically engineered with mice metallothionein I.

Contamination caused by heavy metals in wastewater has a high potential of risk because they easily penetrate in to the trofic chain accumulating as organometallic compounds. In this work, the expression of mice metallothionein in E. coli (pMt-Thio) was examined as a strategy to enhance metal biosorption efficiency of bacterial biosorbents for Pb(II) and Cd(II) ions. The results showed that pMt-Thio led to significant increase in overall biosorption capacity, especially for biosorption of Pb. Isotherms and kinetic of biosorption were evaluated in this designed system. The influence of metal concentration in solution is discussed in terms of Langmuir and Freundlich isotherm and constants. The Langmuir model was found to correlate better with the experiment data. The biomass showed maximum capacities according to Langmuir adsorption model of 28.14 mgPb/gpMt-Thio and 24.27 mgCd/gpMt-Thio. The study proved that pMt-Thio is a suitable material for the removal of the heavy metal ions studied from aqueous solutions, achieving removal efficiencies higher than 90% for Pb(II) and higher than 40% for Cd(II), and could be considered as a potential material for treating effluent polluted with Cd(II) and Pb(II) ions.

Biosorption of Pb2+ and Cd2+ in a fixed bed column with immobilised Chorella sp. biomass.

The biosorption of Pb2+ and Cd2+ in a fixed bed column by immobilised Chlorella sp. was characterised in a fixed bed column. Effect of initial concentration of Pb2+ and Cd2+, pH, and pellet size on the biosorption capacity was studied, at laboratory scale, using a factorial experiment design 2(3), in a 10 cm heightx1 cm of diameter continuous flow column packed with immobilised biomass. Equilibrium uptake of Pb2+ and Cd2+, increased with increasing initial metal ion concentration. It was favoured to pH 5, with a pellet of 5 mm of diameter. Langmuir model described the biosorption equilibrium of both metals.The biosorption of each single cation was studied too in a large column (50 cm heightx5 cm of diameter) at bench scale with a range of flow of 40 to 80 mL min(-1). The mass transfer coefficient was determined fitting the experimental data to continuity equations that were discretised in the radial terms with orthogonal collocation method.