Ag2S nanoparticles (NPs) emerge as a unique system that simultaneously features in vivo near‐infrared (NIR) imaging, remote heating, and low toxicity thermal sensing. In this work, their capabilities ...are extended into the fields of optical coherence tomography (OCT), as contrast agents, and NIR probes in both ex vivo and in vivo experiments in eyeballs. The new dual property for ocular imaging is obtained by the preparation of Ag2S NPs ensembles with a biocompatible amphiphilic block copolymer. Rather than a classical ligand exchange, where surface traps may arise due to incomplete replacement of surface sites, the use of this polymer provides a protective extra layer that preserves the photoluminescence properties of the NPs, and the procedure allows for the controlled preparation of submicrometric scattering centers. The resulting NPs ensembles show extraordinary colloidal stability with time and biocompatibility, enhancing the contrast in OCT with simultaneous NIR imaging in the second biological window.
In recent years, Ag2S nanoparticles have shown great potential in nanomedicine, specifically in areas such as near‐infrared (NIR) imaging, photothermal therapy, and photoluminescence nanothermometry. In this work, biocompatible and size‐controlled ensembles of Ag2S nanoparticles demonstrate their great dual performance as bright NIR probes and enhancers of the optical coherence tomography signals in ex vivo and in vivo studies.
Low-pH cements are designed to be used in underground repositories for high level waste. When they are based on Ordinary Portland Cements (OPC), high mineral admixture contents must be used which ...significantly modify their microstructure properties and performance. This paper evaluates the microstructure evolution of low-pH cement pastes based on OPC plus silica fume and/or fly ashes, using Mid-Infrared and Near-Infrared spectroscopy to detect cement pastes mainly composed of high polymerized C-A-S-H gels with low C/S ratios. In addition, the lower pore solution pH of these special cementitious materials have been monitored with embedded metallic sensors. Besides, as the use of reinforced concrete can be required in underground repositories, the influence of low-pH cementitious materials on steel reinforcement corrosion was analysed. Due to their lower pore solution pH and their different pore solution chemical composition a clear influence on steel reinforcement corrosion was detected.
Fire has been an integral part of ecosystem functioning in many biomes for a long time, but the increased intensity and frequency of wildfires often affect plant diversity and carbon storage. ...Prescribed burning is one of the alternatives to forest fuel management where the fire is controlled and carried out under a determined set of weather conditions and objectives. The effect of prescribed burning on plant diversity and carbon (C) storage has not been studied widely. The objective of this study was to evaluate the effect of prescribed burning on plant diversity indices, biomass stocks, and soil C storage in the tropical highland forests of Southern Mexico. We assessed plant diversity and carbon stocks at 21 sampling sites: seven with prescribed burning, seven non-burning, and seven with wildfires. We calculated tree biodiversity indices, stand structural properties, and species composition among burning treatments. We quantified C stocks in vegetation biomass by using an allometric equation and forest litter by direct sampling. We analyzed 252 soil samples for soil organic C content and other properties. The results showed that the biodiversity index was higher in sites with prescribed burning (Shannon index, H = 1.26) and non-burning (H = 1.14) than in wildfire sites (H = 0.36). There was a greater similarity in plant species composition between non-burning and prescribed burning sites compared to wildfire sites. Prescribed burning showed a positive effect on soil carbon storage (183.9 Mg C ha−1) when compared to wildfire (144.3 Mg C ha−1), but the difference was not statistically significant (p > 0.05) in biomass stocks. Prescribed burning in this study conserved plant diversity as well as soil carbon stocks compared to non-burning, the opposite of what we found in wildfires.
Ag
S nanoparticles (NPs) emerge as a unique system that simultaneously features in vivo near-infrared (NIR) imaging, remote heating, and low toxicity thermal sensing. In this work, their capabilities ...are extended into the fields of optical coherence tomography (OCT), as contrast agents, and NIR probes in both ex vivo and in vivo experiments in eyeballs. The new dual property for ocular imaging is obtained by the preparation of Ag
S NPs ensembles with a biocompatible amphiphilic block copolymer. Rather than a classical ligand exchange, where surface traps may arise due to incomplete replacement of surface sites, the use of this polymer provides a protective extra layer that preserves the photoluminescence properties of the NPs, and the procedure allows for the controlled preparation of submicrometric scattering centers. The resulting NPs ensembles show extraordinary colloidal stability with time and biocompatibility, enhancing the contrast in OCT with simultaneous NIR imaging in the second biological window.
Packaging materials play an essential role in the preservation and marketing of food and other products. To improve their conservation capacity, antimicrobial agents that inhibit bacterial growth are ...used. Biopolymers such as starch and chitosan are a sustainable alternative for the generation of films for packaging that can also serve as a support for preservatives and antimicrobial agents. These substances can replace packaging of synthetic origin and maintain good functional properties to ensure the quality of food products. Films based on a mixture of corn starch and chitosan were developed by the casting method and the effect of incorporating cellulose nanocrystals (CNC) at different concentrations (0 to 10%
/
) was studied. The effect of the incorporation of CNC on the rheological, mechanical, thermal and barrier properties, as well as the antimicrobial activity of nanocomposite films, was evaluated. A significant modification of the functional and antimicrobial properties of the starch-chitosan films was observed with an increase in the concentration of nanomaterials. The films with CNC in a range of 0.5 to 5% presented the best performance. In line with the physicochemical characteristics which are desired in antimicrobial materials, this study can serve as a guide for the development this type of packaging for food use.
A bending vector sensor based on a ring laser and super-mode interference in a seven-core fiber (SCF) is presented. The super-mode interference is originated via a Mach–Zehnder interferometer ...constructed with an SCF spliced between two single-mode fibers. The interference modulates the cavity laser losses of an erbium-doped ring cavity laser. As the interferometer structure is bent, the interference pattern suffers a wavelength shift, reconfiguring the cavity losses and tuning the laser emission. When the interferometer structure is bent in different directions, the cavity losses are rearranged differently depending on the direction, resulting in different laser outputs. Relating the laser output emission to the bending position, a bending vector sensor is obtained. The identification of the bending direction is related to the peak intensity, whereas the curvature magnitude to the wavelength peak.
•Demonstration of a laser bending sensor based on interference in a seven-core fiber.•Determination of four bending directions with behavior of more than those directions.•Favorable temporal stability with minimal fluctuations in wavelength and intensity.
Calcium aluminate cement (CAC) is less commonly used as ordinary Portland cements (OPCs) for structural concrete, is relatively expensive, but may have certain advantages when used for solidification ...of wastes; it introduces rapid strength gain and has a higher resistance to chemical attack than OPC. However, the most widely identified degradation process suffered by CAC is the so‐called conversion of hexagonal calcium aluminate hydrate to a cubic form. Mixes of CAC with silica fume (SF) or fly ash (FA) represent an interesting alternative for the stabilization of CAC hydrates, which might be attributed to a microstructure based mainly on aluminosilicates. This paper deals with the microstructure of cement pastes fabricated with binders of CAC–SF and CAC–FA, and their evolution over time. Mid infrared and near infrared spectroscopy have been used to assess the microstructure of these formulations. Microstructural characterization was completed by backscattering electron microscopy observation and microanalysis.
This study aims to analyze the effects of supercritical carbonation (CO2 at 20 MPa and 318 K) on the physicochemical properties of ordinary Portland cement pastes. The evolution of the main ...crystalline phases of the cement pastes during carbonation was determined by means of X-ray diffraction and thermogravimetric analysis. The pore structure was analyzed by low-temperature N2 adsorption−desorption and mercury intrusion porosimetry techniques. Finally, the microstructure of the samples was observed by using scanning electron microscopy coupled with energy-dispersive X-ray detection for chemical analysis. For a natural carbonation process, diffusion of CO2 into the pores of the cement paste is considered as the rate-controlling step. Instead, the accelerated reaction kinetics of calcium carbonate precipitation in the supercritical process was chemically controlled by the detachment of calcium ions from solid portlandite or CSH gel. The total pore volume of the studied cement pastes decreased with carbonation, which was associated with the deposition of the formed CaCO3. Samples carbonated under the supercritical conditions developed a higher volume of gel pores than those obtained by natural carbonation.
Liver cirrhosis is one of the main leading causes of death in Mexico. Some chronic liver diseases (CLD) are Alcoholic Liver Disease (ALD), Autoimmune Liver Disease (AILD), Hepatitis B (HBV), ...Hepatitis C (HCV), and Non-Alcoholic Steatohepatitis (NASH). In Mexico, ALD and HCV are the leading causes of CLD. Objective: To analyze the incidence of CLD in a liver unit (LU) over 25 years.
Clinical records of patients who attended for the first time to LU, from January 1995 to December 2019 were reviewed. There were 2780 patients with CLD, and 2668 filled the inclusion criteria with available clinical records. The diagnosis of CLD was made according to international guidelines. Inclusion criteria: patients with CLD in their first visit, with or without cirrhosis. Exclusion criteria: acute liver disease, <18 years old. Patients were divided by etiology. This study was observational, descriptive and the sampling was carried out in a non-probabilistic and convenient way. Intervals of time were group A (GA) 1995-2003, group B (GB) 2004-2011 and group C (GC) 2012-2019. A one-way ANOVA was used to determine the differences between these groups.
A statistically significant difference was found in the AILD, ALD and NASH groups, as determined by a one-way ANOVA (p=0.036, p=0.011 and p=<0.00). A Tukey post hoc test showed that AILD cases in GB were higher than GA (p=0.029). The same trend was observed in ALD cases, which also showed an increase between the GA and GC (p=0.012). For NASH cases, each period showed an increase (p=0.005AB, p=<0.001AC, p=0.013BC). HCV and HBV showed no statistically significant changes (Figure).
In Mexico, there is scarce information on the incidence of CLD. This study showed a higher NASH incidence (43%) than the previously reported (29%)1 as well as prevalence (23%)2 in cirrhotic patients. The incidence of HAI in this study was 17%, similar to a previous study of 16%1 in cirrhotic. Previously reported prevalence was 7.3%2 in cirrhotic patients. ALD incidence was 15%, previously reported in 23%1, and a prevalence of 31%2 in cirrhotic patients. HCV incidence had no significant changes (16%), but it was lower than previously reported (22%)1.
This is the first study that reports an incidence of CLD in patients with or without cirrhosis. In the northeast of the country, the incidence of NASH has increased significantly during the last 25 years, becoming the most common CLD. This study found an AILD incidence similar to a previous report.1 ALD showed moderate elevation compared to NASH, and HCV began to decrease.
The authors declare that there is no conflict of interest.
ABSTRACT Tropical forests plays a vital role in mitigating atmospheric CO2 but the retention capacity of such ecosystems has changed greatly due to increasing anthropogenic pressures, of which ...firewood extraction is the main one activity in rural areas. The purpose of this research was to evaluate the biomass stocks of pine and oak forests with different pressure of fuelwood extraction in Chiapas, Mexico. The study was carried out in four locations in the state of Chiapas, southern Mexico; two of them with high extraction levels and the other two with lower extraction levels. Pine and Oak forests are the predominant forest types in the region. A total of sixteen plots of 400 m2 were established to measure the biomass stocks of the trees with > 7.5 cm DBH. Published allometric equations were used to quantify the biomass stocks. The average biomass of the pine forest with low fuelwood extraction was 213.4 Mg ha-1, and that of the oak forest was 189.5 Mg ha-1. On the other hand, the biomass stocks of the pine forest with high fuelwood extraction was 138.2 Mg ha-1, and that of the oak forest was 92.0 Mg ha-1. Communities with agricultural diversification like apiculture and agroforestry practices were found more effective in forest biomass conservation when compared to those who are only dedicated to Milpa cultivation and extensive bovine livestock production. The adoption of silvopasture systems, the use of crop residues and the use of ecological cooking stoves can be the alternatives to reduce forest fuelwood extraction.
RESUMO As florestas tropicais desempenham um papel vital na mitigação do CO2 atmosférico, mas a sua capacidade de retenção mudou devido ao aumento das pressões antropogênicas, das quais a extração de lenha é a principal atividade nas áreas rurais. O objetivo deste estudo foi avaliar o estoque de biomassa nas florestas de pinus e carvalho com diferente pressão na extração de lenha em Chiapas, México. O estudo foi realizado em quatro localidades no Estado de Chiapas, sul do México, duas com maior extração de lenha e duas com menor extração. Florestas de pinus e carvalho predominam na região. Um total de dezesseis parcelas de 400 m2 foram estabelecidas para medir os estoques de biomassa das árvores com DAP > 7,5 cm. A biomassa foi calculada mediante equações alométricas publicadas. O estoque médio de biomassa na floresta de pinus com menor extração de lenha foi de 213,4 Mg ha-1 e da floresta de carvalho foi de 189,5 Mg ha-1. Por outro lado, o estoque de biomassa em florestas de pinus com maior extração de lenha foi de 138,2 Mg ha-1 e da floresta de carvalho foi de 92,0 Mg ha-1. Comunidades com diversidade agrícola, como apicultura e práticas florestais, foram consideradas mais eficazes na conservação da biomassa florestal quando comparadas com aquelas que se dedicam ao cultivo exclusivo de Milpa e à produção extensiva de gado bovino. O estabelecimento de sistemas silvipastoris, uso dos resíduos agrícolas e o uso de fogões ecológicos podem ser alternativas para reduzir a extração de lenha florestal.
PDF
