Sustainable Biocomposites for Structural Applications with Environmental Affinity.

In this work, we report a facile preparation of biocomposites using a chitosan matrix that is reinforced with morphed graphene in amounts from 1 to 5 wt % C. The composites are processed by milling and conventional sintering. The morphed graphene additions show clear improvements in mechanical properties, having a direct correlation with temperature in particular for 180 °C. Higher temperatures are detrimental to chitosan and the properties drop because chitosan degrades. Mechanical properties in the composite such as yield strength and compressive strength increase between 40 and 50% with respect to the pure chitosan samples. The Young's modulus presents a drop of approximately 10%, but the fracture toughness increases up to 3.5 fold. The properties of our sustainable composites are comparable to those seen in polymers such as polyethylene, polypropylene, nylon, and poly(methyl methacrylate), among other commodity or single use plastics. The enhancement in the mechanical properties is attributed to the morphed graphene embedded chitosan matrix that generates a network of intergranular "anchors" that hold the chitosan crystals in place, preventing failure. The composites can be molded into near-net-shape products, machined, or shaped using various methods including laser lithography. These studies demonstrate the feasibility of fabricating biocomposites with different architectures and sizes for disposable structural components. Both chitosan and the composites are compostable and biodegradable with the potential to sustain plant growth when discarded. In addition, morphed graphene and chitosan are produced from byproducts or waste, which may result in a negative carbon footprint on the environment.

Hybrid Cements with ZnO Additions: Hydration, Compressive Strength and Microstructure.

The effect of ZnO has already been studied for Portland cement, but the study of its impact on hybrid pastes is scarce. Thus, in this investigation, the influence of ZnO addition on hydration, compressive strength, microstructure, and structure of hybrid pastes is presented. The analyses were made by setting time tests, compressive strength tests, X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis with differential scanning calorimetry, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The results indicate that the setting time of the cements was delayed up to 39 min with additions of 3 wt% ZnO. Alternatively, the higher values of compressive strength were observed when 0.5 wt% ZnO was added to the cements for all curing days. In addition, no important differences in the microstructure of samples with different additions of ZnO were observed after 28 days of curing. It is expected that the use of ZnO contributes to the delay of the setting time and the increase of the compressive strength without negatively modifying the microstructure of hybrid pastes.

Bioaccumulation of Metals in Cultured Carp (Cyprinus carpio) from Lake Chapala, Mexico.

Chapala, the largest lake in Mexico, has a great potential for aquaculture and a community of some 2500 fishermen who are interested in this activity. However, diverse reports over the past two decades suggest that the fish there are contaminated with heavy metals, raising concern among consumers. Although more recent scientific studies have clarified that the metal content in the edible parts of fish is below allowable limits, the negative perception persists. The present study, therefore, was designed to evaluate the bioaccumulation of the metals Cu, Zn, Pb, As, and Cd in organs such as the muscles, liver, and gills of carp (Cyprinus carpio) cultured in Lake Chapala, and compared the results to fish cultured in a pond. Results after 473 days of monitoring showed that metal bioaccumulation in the muscles of the carp increased by 1.71, 0.50, and 12.36 µg/kg for Cu, Cd, and Pb, respectively, but Zn and As levels decreased by 7.84 and 131.7 µg/kg, respectively. The livers showed concentrations one or two times higher than the muscles in the case of Pb, Cu, Zn, and Cd. According to these results, the metal concentrations in the edible parts of these fish were below international standards for human consumption, and no significant differences were found between the bioaccumulation patterns in the muscles and livers of the carp cultured in the lake and those raised in the pond, except for Cd and Pb in the liver. Finally, no correlations were found between metal concentrations in the fish and lake sediments.

Ichthyofaunal list of the continental slope of the southern Gulf of Mexico.

Four oceanographic cruises were carried out between April 2011 and May 2013 on the continental slope of the southern Gulf of Mexico (GoM) in a depth range of 290 to 1200 m on board the R/V JUSTO SIERRA. A total of 91 trawls covered a total swept area of 170.49 hectares. We recorded 177 fish species belonging to 80 families. Fifteen species extended their distribution into the south of the gulf and 37 increased their depth ranges. Five species could have commercial importance: Aphanopuscarbo Lowe, 1839; Hydrolagusmirabilis (Collett, 1904); Helicolenusdactylopterus (Delaroche, 1809); Lophiusgastrophysus Miranda Ribeiro, 1915, and Merlucciusalbidus (Mitchill, 1818). The most abundant species were Polymixialowei Günther, 1859; Parasudistruculenta (Goode & Bean, 1896); M.albidus, Chlorophthalmusagassizi Bonaparte, 1840; Dibranchusatlanticus Peters, 1876; Nezumiaaequalis (Günther, 1878); Yarrellablackfordi Goode & Bean, 1896; and Laemonemabarbatulum Goode & Bean, 1883. High values of fish species richness, diversity, and evenness were registered throughout the study area. A high percentage of the fish species (97%) collected during this project are distributed in the entire GoM. Most of the species showed a wide depth distribution; however, a vertical zonation of species can be observed.

Descriptive, Longitudinal Study Results Applied to Statistical Models to Assess the Impact of Early Microbiological Cultures on the Economic Burden of Treatment for Infected Diabetic Foot Ulcers at a Mexican Public Health Facility.

Infection plays a critical role in health care and impacts the cost of the treatment of diabetic foot ulcers (DFU). To examine the cost reduction associated with the multidisciplinary treatment of infected DFU (IDFU) by obtaining early (ie, within 48 hours of admission) microbiological culture results, a descriptive, longitudinal study was conducted. Data were collected prospectively from patient medical charts of a cohort of 67 patients (mean age, 56.14 ± 12.3 years; mean duration of diabetes, 14.95 ± 8 years) with IDFU treated at a Mexican public health facility from January 1 to April 30, 2010. Information included demographic data (age, gender, marital status, time elapsed since first diagnosis of diabetes mellitus type 2 [DM2]), and the following clinical records: Wagner classification, bacterium type, antimicrobial resistance, length of hospital stay, and the antibiotic schedule utilized, as well as number and type of laboratory tests, medications, intravenous therapy, surgical and supportive treatment, type and number of specialists, and clinical outcome. Microcosting was used to calculate the unit cost of each medical treatment element. Using the Monte Carlo and Markov predictive simulation economical models, cost reduction associated with early identification of the specific microorganism through bacterial culture in IDFU was estimated. Based on the statistical results, differences between real and estimated costs when including early microbiological culture were identified and the number and type of most common species of infectious bacteria were detected. The total cost observed in the patient cohort was $502 438.04 USD, mean cost per patient was $7177.69 ± $5043.51 USD, and 72.75% of the total cost was associated with the hospital stay length. The cost of the entire treatment including antibiotics was $359 196.16 USD; based on the simulation of early microbiological culture, the model results showed cost could be reduced by 10% to 25% (in this study, the cost could be as low as $304 624.63 USD). The use of early microbiological cultures on IDFU to determine the appropriate antibiotic can reduce treatment costs by >30% if hospital stay is part of the consideration.