► Hydrothermal carbonization was employed to upgrade fuel quality of waste biomass. ► The improved fuel qualities of the biochars are similar to those of lignite. ► Hydrothermal carbonization ...narrowed the differences among different biomasses. ► The biochars have the potential to be used as a coal substitutes for heat production.
The application of biomass-derived energy is gaining in importance due to decreasing supply of fossil fuels and growing environmental concerns. In this study, hydrothermal carbonization was used to upgrade waste biomass and increase its energy density at temperatures ranging from 150 to 375°C and a residence time of 30min. The produced biochars were characterized and their fuel qualities were evaluated. The biochars were found to be appropriate for direct combustion/co-combustion with low rank coals for heat production. Chemical analysis showed that the pre-treated biomass has improved fuel qualities compared to the raw biomass, such as decreased volatile matter/(volatile matter+fixed carbon) ratio, increased carbon content and lower ash content. The energy density of biochar increased with increasing hydrothermal temperature, with higher heating values close to that of lignite. The evolution of biomass under hydrothermal carbonization, as determined by FT-IR and 13C NMR, showed that most hemicellulose and cellulose were decomposed at below 250°C while the degradation of lignin only occurs at higher temperatures. The aromaticity of biochars increased with increasing temperature, and considerable amounts of lignin fragments remained in the biochars after supercritical water treatment. The biochars had increased ignition temperatures and higher combustion temperature regions compared to raw biomass feedstock. An optimum temperature of 250°C was found for hydrothermal carbonization of waste biomass for the production of biochars for heat generation. The present study showed that hydrothermal carbonization narrowed the differences in fuel qualities among different biomass feedstocks. It also offers a promising conversion process for the production of high energy density biochar which has potential applications in existing coal-fired boilers without modifications.
The sequence of heterocyclic bases on the interior of the DNA double helix constitutes the genetic code that drives the operation of all living organisms. With this said, it is not surprising that ...chemical modification of cellular DNA can have profound biological consequences. Therefore, the organic chemistry of DNA damage is fundamentally important to diverse fields including medicinal chemistry, toxicology, and biotechnology. This review is designed to provide a brief overview of the common types of chemical reactions that lead to DNA damage under physiological conditions.
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► Energy rich hydrochars were synthesized by HTC of palm empty fruit bunches. ► Formation of hydrochars relies on a dehydration and decarboxylation process. ► Hydrochars were ...characterized by FE-SEM, FTIR, BET, XRD and TGA-DTG. ► Hydrochar presented in this work has unique chemical properties. ► Potential applications of hydrochars include fuels, energy sources and adsorbents.
A carbon-rich solid product, denoted as hydrochar, was synthesized by hydrothermal carbonization (HTC) of palm oil empty fruit bunch (EFB), at different pre-treatment temperatures of 150, 250 and 350°C. The conversion of the raw biomass to its hydrochar occurred via dehydration and decarboxylation processes. The hydrochar produced at 350°C had the maximum energy-density (>27MJkg−1) with 68.52% of raw EFB energy retained in the char. To gain a detailed insight into the chemical and structural properties, carbonaceous hydrochar materials were characterized by FE-SEM, FT-IR, XRD and Brunauer–Emmett–Teller (BET) analyses. This work also investigated the influence of hydrothermally treated hydrochars on the co-combustion characteristics of low rank Indonesian coal. Conventional thermal gravimetric analysis (TGA) parameters, kinetics and activation energy of different hydrochar and coal blends were estimated. Our results show that solid hydrochars improve the combustion of low rank coals for energy generation.
Hydrothermal carbonization (HTC) of biomass involves contacting raw feedstock with hot, pressurized water. Through a variety of hydrolysis, dehydration, and decarboxylation processes, gaseous and ...water-soluble products are produced, in addition to water itself and a solid char. In this experimental effort, a 2 L Parr stirred pressure vessel was used to apply the HTC process to a mixed wood feedstock. The effects of the reaction conditions on product compositions and yields were examined by varying temperature over the range of 215−295 °C and varying reaction hold time over the range of 5−60 min. With increasing temperature and time, the amounts of gaseous products and produced water increased, while the amount of HTC char decreased. The energy density of the char increased with reaction severity. At reaction conditions of 255 °C for 30 min, the HTC char had 39% higher energy density than the raw biomass feedstock. Aqueous solutions from HTC experiments at lower temperatures (215−235 °C) contained significant levels of sugars. At higher temperatures (255−295 °C), greatly reduced concentrations of sugars were observed, while concentrations of acetic acid increased. A two-step HTC process involving low- and high-temperature regimes may be advantageous to maximize both the recovery of sugars and production of energy-dense char.
Apurinic/apyrimidinic (AP) sites, that is, abasic sites, are among the most frequently induced DNA lesions. Spontaneous or DNA glycosylase-mediated β-elimination of the 3′-phosphoryl group can lead ...to strand cleavages at AP sites to yield a highly reactive, electrophilic 3′-phospho-α,β-unsaturated aldehyde (3′-PUA) remnant. The latter can react with amine or thiol groups of biological small molecules, DNA, and proteins to yield various damaged 3′-end products. Considering its high intracellular concentration, glutathione (GSH) may conjugate with 3′-PUA to yield 3-glutathionyl-2,3-dideoxyribose (GS-ddR), which may constitute a significant, yet previously unrecognized endogenous lesion. Here, we developed a liquid chromatography tandem mass spectroscopy method, in combination with the use of a stable isotope-labeled internal standard, to quantify GS-ddR in genomic DNA of cultured human cells. Our results revealed the presence of GS-ddR in the DNA of untreated cells, and its level was augmented in cells upon exposure to an alkylating agent, N-methyl-N-nitrosourea (MNU). In addition, inhibition of AP endonuclease (APE1) led to an elevated level of GS-ddR in the DNA of MNU-treated cells. Together, we reported here, for the first time, the presence of appreciable levels of GS-ddR in cellular DNA, the induction of GS-ddR by a DNA alkylating agent, and the role of APE1 in modulating its level in human cells.
Background Clinically relevant postoperative pancreatic fistulas (CR-POPF) are serious inherent risks of pancreatic resection. Preoperative CR-POPF risk assessment is currently inadequate and rarely ...disqualifies patients who need resection. The best evaluation of risk occurs intraoperatively, and should guide fistula prevention and response measures thereafter. We sought to develop a risk prediction tool for CR-POPF that features intraoperative assessment and reveals associated clinical and economic significance. Study Design Based on International Study Group of Pancreatic Fistula classification, recognized risk factors for CR-POPF (small duct, soft pancreas, high-risk pathology, excessive blood loss) were evaluated during pancreaticoduodenectomy. An optimal risk score range model, selected from 3 different constructs, was first derived (n = 233) and then validated prospectively (n = 212). Clinical and economic outcomes were evaluated across 4 ranges of scores (negligible risk, 0 points; low risk, 1 to 2; intermediate risk, 3 to 6; high risk, 7 to 10). Results Clinically relevant postoperative pancreatic fistulas occurred in 13% of patients. The incidence was greatest with excessive blood loss. Duct size <5 mm was associated with increased fistula rates that rose with even smaller ducts. These factors, together with soft pancreatic parenchyma and certain disease pathologies, afforded a highly predictive 10-point Fistula Risk Score. Risk scores strongly correlated with fistula development (p < 0.001). Notably, patients with scores of 0 points never developed a CR-POPF, while fistulas occurred in all patients with scores of 9 or 10. Other clinical and economic outcomes segregated by risk profile across the 4 risk strata. Conclusions A simple 10-point Fistula Risk Score derived during pancreaticoduodenectomy accurately predicts subsequent CR-POPF. It can be readily learned and broadly deployed. This prediction tool can help surgeons anticipate, identify, and manage this ominous complication from the outset.
•Hydrothermal carbonization (HTC) of biomass was conducted continuously in a TSE-based reactor system.•The fast HTC (FHTC) reactor system produces hydrochar in higher yields than a batch reactor ...system.•Severity factor (SF) is a useful metric for characterizing reaction conditions in different reactor systems.
Hydrothermal carbonization (HTC) has become an accepted means of converting a wide variety of lignocellulosic feedstocks into solid hydrochars, which have improved physical and chemical properties compared to raw biomass. To date, HTC applications have involved batch or semi-continuous process systems, which has limited their economic viability. The work presented here describes a fully-continuous HTC process, made possible by use of a specially modified twin-screw extruder (TSE). The reaction time within this fast HTC (FHTC) reactor system is very short (20–30sec) as compared to a typical batch reactor. Therefore, the concept of reaction ‘severity factor’ is used when comparing the FHTC products with those produced in other reactor systems. While solid hydrochar produced in the FHTC system has different physical properties than hydrochar from batch reactor systems, these materials exhibit similar energy densification and pelletization behavior, when produced under comparable severity conditions. However, total hydrochar yields are considerably higher from the FHTC reactor compared to batch reactor systems. This is a consequence of the de-pressurization process in the FHTC system, whereby most water-soluble organic products are retained in the hydrochar, rather than exiting the process in a separate aqueous product stream. FHTC treatment of loblolly pine at a severity factor of 5.3 (290°C) produced a hydrochar yield of nearly 85% (based on dry feedstock mass). Condensation of the flashed vapor products provided a relatively clean water stream, containing only 1.2% organics – primarily furfural and acetic acid. Recovery of these organics and recycling of the condensed water would further improve the cost-effectiveness of FHTC operations.
Biofuels are of rapidly growing interest for reasons of energy security, diversity, and sustainability – as well as for greenhouse gas mitigation. In recent years, the U.S. has enacted regulations – ...and adopted aggressive goals – to encourage increased usage of biofuels. Individual States (especially California) have taken even stronger positions with respect to biofuels. Initial efforts have focused mainly on ethanol, produced via fermentation of sugars from grains (especially corn). Today's R&D focus is on “2nd Generation Biofuels” that are produced from a variety of biomass feedstocks utilizing a wide range of conversion technologies. This paper summarizes policy and regulatory drivers for biofuels in the U.S., describes usage trends and projections, and highlights major R&D efforts to promote development and commercialization of 2nd Generation Biofuels. R&D is being conducted in many areas, including biomass resource assessment, development of new biomass feedstocks, improved conversion technologies, and integration of systems. Other important considerations include fuel quality and specifications, as well as requirements for blending, distribution, and storage. Considerable R&D, policy, and regulatory efforts are also focused on the energy and environmental consequences of biofuels. This includes not only direct emissions associated with vehicular uses, but also the fuels' life-cycle impacts with respect to total energy usage, greenhouse gas emissions, and multi-media effects. Due to the wide diversity of biomass feedstocks, conversion technologies, and systems integration approaches, the life-cycle impacts of biofuels can vary widely.
In 2014, the Association for Multicultural Counseling and Development (AMCD) appointed a committee to revise the Multicultural Counseling Competencies developed by Sue, Arredondo, and McDavis in and ...operationalized by Arredondo et al. in . This article reflects the updated competencies, titled the Multicultural and Social Justice Counseling Competencies (MSJCC; Ratts, Singh, Nassar‐McMillan, Butler, & McCullough, ), which were endorsed by AMCD on June 29, 2015, and by the American Counseling Association on July 20, 2015. A conceptual framework of the MSJCC visually depicts the relationships among the competencies' key constructs: multicultural and social justice praxis, quadrants, domains, and competencies. Implications are discussed.
En 2014, la Asociación para la Consejería y el Desarrollo Multicultural (AMCD, en sus siglas en inglés) formó un comité para revisar las Competencias en Consejería Multicultural desarrolladas por Sue, Arredondo y McDavis en 1992 y operacionalizadas por Arredondo et al. en 1996. Este artículo refleja las competencias actualizadas, denominadas Competencias en Consejería Multicultural y de Justicia Social (MSJCC, en sus siglas en inglés; Ratts, Singh, Nassar‐McMillan, Butler, & McCullough, 2015a), que fueron avaladas por la AMCD el 29 de junio de 2015 y por la Asociación Americana de Consejería el 20 de julio de 2015. Un marco conceptual de las MSJCC muestra visualmente las relaciones entre los constructos principales de las competencias: la praxis multicultural y en justicia social, los cuadrantes, dominios y competencias. Se discuten las implicaciones.
Synthetic scheme for the formation pathway of metallic nickel nanoparticles supported on the hydrochar derived from lignin-rich precursory biomass.
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•Well-dispersed metallic nickel ...nanoparticles were fabricated on the hydrochar as catalysts.•The role of concentration of precursory nickel ions and calcination temperature were probed.•The average grain size of the metallic Ni NPs can be manipulated between 8 and 13 nm.•The catalysts exhibited enhanced catalytic activity for hydrogen production and tar reduction.
The synthesis of carbon-based nanomaterials, ideally produced via facile, inexpensive approaches, using sustainable resources as precursors, with modulated structures, morphologies and functionalities is still challenging for energy applications. This work developed a mild one-step hydrothermal synthesis route for the fabrication of highly dispersed metallic nickel nanoparticles on hydrothermal carbons derived from waste biomass. The roles of precursor nickel ion concentration and calcination temperature in modulating the morphology, location and crystalline size of the nickel nanoparticles as well as the metal-support interactions have been delineated. The average grain size of the metallic nickel nanocrystals on the resultant Ni0.5@HCOp nanocatalysts could be tuned to 8–13 nm by varying the preparation conditions. The catalytic abilities of the Ni-based nanocatalysts towards hydrogen-rich syngas production and tar reduction were then tested in a two-stage reactor system using sewage sludge as biomass feedstock. The catalytic tests showed that the Ni0.5@HCOp catalyst calcined at 700 °C was shown to have stronger metal-support interactions compared to other Ni-based nanocomposites, which provided better suppression of coke deposition and resistance of nickel agglomeration during the catalytic gasification process. This highly active catalyst promoted formation of hydrogen-rich syngas, with up to 109.2 g H2/kg sludge, and tar yields as low as 2.12 mg g−1.
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