Removal of anionic surfactant from aqueous solutions by adsorption onto biochars: characterisation, kinetics, and mechanism.

Biochar, a waste biomass-derived adsorbent, holds promise for decentralised wastewater treatment. However, limited research exists on its efficacy in adsorbing anionic surfactants in wastewater. To address this, the adsorption of sodium dodecyl sulphate (SDS), a common anionic surfactant, was studied using various biochar types: rice husk biochar (RH-550 and RH-700), wheat straw biochar (WS-550 and WS-700) produced at 550°C and 700°C, wood-based biochar (OB), and activated carbon (AC) as a control. The study investigated the impact of pH (3-9), adsorbent loading (1-10 g/L), adsorbent size (<0.5-2.5 mm), contact time (5-180 min), and initial concentration (50-200 mg/L) on SDS removal. Under optimised conditions (100 mg/L SDS, 4 g/L adsorbent, 1-2 mm particle size, pH 8.3, and 180 min contact time), maximum SDS removals were RH-550 (78%), RH-700 (82.4%), WS-550 (89.5%), WS-700 (90.4%), AC (97%), and OB (88.4%). Among the tested adsorbent materials, WS-550 exhibited the highest SDS adsorption capacity at 66.23 mg/g compared to AC (80.65 mg/g), followed by RH-550 (49.75 mg/g), OB (45.87 mg/g), RH-700 (43.67 mg/g), and WS-700 (42.74 mg/g). SDS adsorption followed a pseudo-second-order kinetic model, indicating chemisorption on the adsorbent surface. The Freundlich isotherm model exhibited a better fit for the experimental data on SDS adsorption using all tested adsorbents except for RH-550. This study showed that biochars produced from agricultural and forestry residues are effective adsorbents for SDS in aqueous solutions and can be a promising sustainable and low-cost material for the treatment of greywater containing anionic surfactants (e.g. handwashing, laundry, kitchen, and bathroom greywaters).

Effect of rhizobium and gibberellin on the production of hydroponic green forage of red clover (Trifolium pratense L.) variety quiñequeli.

The purpose of the present investigation was to determine the effect of rhizobium and gibberellin on the production of hydroponic green forage from red clover (Trifolium pratense L.) variety quiñequeli, four variables were measured: plant height, biomass weight, grass weight and root weight. The treatments were T0: 0%, T1: 10%, T2: 20%, T3: 30% and T4: 40% of Rhizobium before germination and Gibberellin T0: 0g, T1: 2.4g; T2: 3.3g; T3: 4.3 and T4: 5.3g each treatment with 6 repetitions, three applications on days 5, 10, 15 and 20 of growth. Data were analyzed with DCA, ANOVA and DUNCAN's multiple comparisons test; the results obtained were: first measurement with rhizobium without gibberellin there were no statistical differences, second and third measurement with Gibberellin application did not present statistical differences and the fourth measurement presented statistical difference (α=0.05), average height of the plant with a mean of 12.82 cm, T4 was higher, in biomass a statistical difference was obtained with a mean of 3.056 kg, T3 was higher, weight of grass and root did not present statistical differences; concluding that the use of rhizobium and gibberellin could be a usable alternative in the production of hydroponic green fodder, to alleviate the problems of fodder scarcity in dry season, its use being recommended in high Andean livestock.

Computational design of mechanically coupled axle-rotor protein assemblies.

Natural molecular machines contain protein components that undergo motion relative to each other. Designing such mechanically constrained nanoscale protein architectures with internal degrees of freedom is an outstanding challenge for computational protein design. Here we explore the de novo construction of protein machinery from designed axle and rotor components with internal cyclic or dihedral symmetry. We find that the axle-rotor systems assemble in vitro and in vivo as designed. Using cryo-electron microscopy, we find that these systems populate conformationally variable relative orientations reflecting the symmetry of the coupled components and the computationally designed interface energy landscape. These mechanical systems with internal degrees of freedom are a step toward the design of genetically encodable nanomachines.

[Digestive diseases in the elderly]. / Enfermedades digestivas en el anciano.

This study was carried out in two phases. First a survey was done, interviewing 57 apparently healthy persons, who were older than 60 years. Information was collected about previous illnesses and any digestive symptoms. Then a prospective study was developed in 43 out patients seen previously in a gastroenterological centre (aged 60 or older). The frequency and type of digestive diseases for this group of patients was established. Nineteen (33.3%) of the former 57 patients from the survey referred frequent digestive discomfort, predominantly symptoms related to the upper gastrointestinal tract, like epigastric pain, meteorism, early satiety, abdominal distention and pyrosis. These symptoms could be in part expected due to the physiological changes seen in the elderly, mainly in the esophagus. In the prospective study, digestive diseases related to the upper gastrointestinal tract were the most common (46.5%), followed by diseases from the colon and rectum (23.2%) and those of the liver, biliar tract and pancreas (16.2%). Taking into account the high incidence of gastrointestinal symptoms in the elderly, we must make special efforts to extend and or complete studies related to the geriatric population in our country. We need to establish rules for the control, prevention and early detection of such illness in order to promote higher standard in the quality of the life of population which will increased considerably in the near future.