Microstructure and carbon storage capacity of hydrated magnesium carbonates synthesized from different sources and conditions

Recently, the mineral carbonation via the reaction of CO2 with saline aquafers received much attention as one of the most promising ways for geologic CO2 storage. This paper reports microstructure and carbon storage capacity of hydrated magnesium carbonates (HMCs) synthesized from different sources, i.e., reject brine and commercial Mg(OH)2 slurry, and under different conditions, i.e., pH (8–14) and Mg(OH)2:CO2 molar ratio (1:1–1:7). Results show that dypingite (Mg5(CO3)4(OH)2·5H2O) is the main phase forming at lower Mg(OH)2:CO2 ratios. An increase in the Mg(OH)2:CO2 ratio and/or pH leads to the precipitation of nesquehonite (MgCO3·3H2O). A unique “house of cards” texture, involving formation of the rosette-like dypingite flakes on the surface of nesquehonite needles, is discovered under elevated pH and Mg(OH)2:CO2 ratios. HMCs synthesized from reject brine exhibit a much higher carbon storage capacity of 82.6% than that produced from the commercial Mg(OH)2 slurry (43.7%). Findings from this study advance understanding of mineral recovery from reject brine and the capture and long-term storage of CO2 in the form of HMCs

Investigation of the properties of MgO recovered from reject brine obtained from desalination plants

In addition to its use in various applications such as those in the agriculture, pharmaceutical and refractory industries, MgO is being investigated as a cement binder due to the low calcination temperatures used during its production and its ability to gain strength by absorbing CO2in construction products. Similar to the dry-route, the reactivity of MgO synthesized from waste water or reject brine via the calcination of the precipitated Mg(OH)2depends on the calcination conditions. This study investigated the influence of two bases, namely ammonia solution (NH4OH) and sodium hydroxide (NaOH), on the properties of Mg(OH)2precipitated and consequently the characteristics of MgO produced under different calcination conditions. The energy consumption of the production of reactive MgO from reject brine via the addition of NH4OH and NaOH was also reported and compared with the industrial production routes to assess the sustainability of the production procedure. The final products were characterized in terms of their specific surface area (SSA) and microstructure. Results indicated that Mg(OH)2synthesized via the addition of NH4OH into reject brine generated a more porous, flake-like morphology than those obtained via the use of NaOH. The SSA and reactivity of NH4OH-based MgO demonstrated a sharper decrease with increasing temperature and duration compared to NaOH-based MgO. Out of all samples, NH4OH-based MgO calcined at 500 °C for 2 h revealed the highest reactivity (SSA of 78.8 m2/g), which was higher than NaOH-based MgO (SSA of 51.4 m2/g)

Coculture of stem cells from apical papilla and human umbilical vein endothelial cell under hypoxia increases the formation of three-dimensional vessel-like structures in vitro

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Linear, Deterministic, and Order-Invariant Initialization Methods for the K-Means Clustering Algorithm

Over the past five decades, k-means has become the clustering algorithm of choice in many application domains primarily due to its simplicity, time/space efficiency, and invariance to the ordering of the data points. Unfortunately, the algorithm's sensitivity to the initial selection of the cluster centers remains to be its most serious drawback. Numerous initialization methods have been proposed to address this drawback. Many of these methods, however, have time complexity superlinear in the number of data points, which makes them impractical for large data sets. On the other hand, linear methods are often random and/or sensitive to the ordering of the data points. These methods are generally unreliable in that the quality of their results is unpredictable. Therefore, it is common practice to perform multiple runs of such methods and take the output of the run that produces the best results. Such a practice, however, greatly increases the computational requirements of the otherwise highly efficient k-means algorithm. In this chapter, we investigate the empirical performance of six linear, deterministic (non-random), and order-invariant k-means initialization methods on a large and diverse collection of data sets from the UCI Machine Learning Repository. The results demonstrate that two relatively unknown hierarchical initialization methods due to Su and Dy outperform the remaining four methods with respect to two objective effectiveness criteria. In addition, a recent method due to Erisoglu et al. performs surprisingly poorly.Comment: 21 pages, 2 figures, 5 tables, Partitional Clustering Algorithms (Springer, 2014). arXiv admin note: substantial text overlap with arXiv:1304.7465, arXiv:1209.196

The pharmacological regulation of cellular mitophagy

Small molecules are pharmacological tools of considerable value for dissecting complex biological processes and identifying potential therapeutic interventions. Recently, the cellular quality-control process of mitophagy has attracted considerable research interest; however, the limited availability of suitable chemical probes has restricted our understanding of the molecular mechanisms involved. Current approaches to initiate mitophagy include acute dissipation of the mitochondrial membrane potential (ΔΨm) by mitochondrial uncouplers (for example, FCCP/CCCP) and the use of antimycin A and oligomycin to impair respiration. Both approaches impair mitochondrial homeostasis and therefore limit the scope for dissection of subtle, bioenergy-related regulatory phenomena. Recently, novel mitophagy activators acting independently of the respiration collapse have been reported, offering new opportunities to understand the process and potential for therapeutic exploitation. We have summarized the current status of mitophagy modulators and analyzed the available chemical tools, commenting on their advantages, limitations and current applications

Influence of Exposure to Imidacloprid on Survivorship, Reproduction and Vitellin Content of the Carmine Spider Mite, Tetranychus cinnabarinus

Occasional reports linking neonicotinoid insecticide applications to field population outbreaks of the spider mite have been a topic of concern for integrated pest management programs. To elucidate the impacts of a neonicotinoid insecticide on the carmine spider mite, Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), the survivorship, reproduction, and vitellin contents of the mite were investigated after exposure to various concentrations of imidacloprid on the V. unguiculata leaf discs at 25°C, 80% RH and a photoperiod of 14:10 (L:D) in the laboratory. The results showed that the field-relevant dose of imidacloprid did not significantly affect the hatch rate of eggs or pre-imaginal survivorship of the mite, while sublethal doses of imidacloprid, previously determined for Myzus persicae, led to a significant increase in the hatch rate of eggs and pre-imaginal survivorship of the mite compared to the untreated control. Adult longevity and fecundity of T. cinnabarinus for imidacloprid-treated populations were slightly prolonged and increased, respectively, but the difference from the untreated control was not significant. The vitellin content in eggs increased significantly after exposure to imidacloprid. Imidacloprid may be one of the major reasons for the outbreak of T. cinnabarinus in the field

Phytochemicals as antibiotic alternatives to promote growth and enhance host health

There are heightened concerns globally on emerging drug-resistant superbugs and the lack of new antibiotics for treating human and animal diseases. For the agricultural industry, there is an urgent need to develop strategies to replace antibiotics for food-producing animals, especially poultry and livestock. The 2nd International Symposium on Alternatives to Antibiotics was held at the World Organization for Animal Health in Paris, France, December 12-15, 2016 to discuss recent scientific developments on strategic antibiotic-free management plans, to evaluate regional differences in policies regarding the reduction of antibiotics in animal agriculture and to develop antibiotic alternatives to combat the global increase in antibiotic resistance. More than 270 participants from academia, government research institutions, regulatory agencies, and private animal industries from >25 different countries came together to discuss recent research and promising novel technologies that could provide alternatives to antibiotics for use in animal health and production; assess challenges associated with their commercialization; and devise actionable strategies to facilitate the development of alternatives to antibiotic growth promoters (AGPs) without hampering animal production. The 3-day meeting consisted of four scientific sessions including vaccines, microbial products, phytochemicals, immune-related products, and innovative drugs, chemicals and enzymes, followed by the last session on regulation and funding. Each session was followed by an expert panel discussion that included industry representatives and session speakers. The session on phytochemicals included talks describing recent research achievements, with examples of successful agricultural use of various phytochemicals as antibiotic alternatives and their mode of action in major agricultural animals (poultry, swine and ruminants). Scientists from industry and academia and government research institutes shared their experience in developing and applying potential antibiotic-alternative phytochemicals commercially to reduce AGPs and to develop a sustainable animal production system in the absence of antibiotics.Fil: Lillehoj, Hyun. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Liu, Yanhong. University of California; Estados UnidosFil: Calsamiglia, Sergio. Universitat Autònoma de Barcelona; EspañaFil: Fernandez Miyakawa, Mariano Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; ArgentinaFil: Chi, Fang. Amlan International; Estados UnidosFil: Cravens, Ron L.. Amlan International; Estados UnidosFil: Oh, Sungtaek. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Gay, Cyril G.. United States Department of Agriculture. Agricultural Research Service; Argentin

Highly Sensitive and Compact THz heterodyne receiver based on HEB and QCL at 2.7 THz

We present the development of a highly sensitive and compact HEB/QCL heterodyne detection system. The HEB mixer is a NbN nano-bridge mounted in an integrated lens-antenna configuration. The local oscillator is a low power consumption and low beam divergence 3 rd order distributed feedback quantum cascade laser with single mode emission at the target frequency of 2.7 THz. A new quasi-optical coupling scheme between the mixer and the local oscillator has been developed that allows the removal of the beam splitter and therefore a better transmission of the RF signal and a more compact detection system. The lowest uncorrected double side band receiver noise temperature of this system is about 880 K