Food web pathway determines how selenium affects aquatic ecosystems: a San Francisco Bay case study

Chemical contaminants disrupt ecosystems, but specific effects may be under-appreciated when poorly known processes such as uptake mechanisms, uptake via diet, food preferences, and food web dynamics are influential. Here we show that a combination of food web structure and the physiology of trace element accumulation explain why some species in San Francisco Bay are threatened by a relatively low level of selenium contamination and some are not. Bivalves and crustacean zooplankton form the base of two dominant food webs in estuaries. The dominant bivalve Potamocorbula amurensis has a 10-fold slower rate constant of loss for selenium than do common crustaceans such as copepods and the mysid Neomysis mercedis (rate constant of loss, ke = 0.025, 0.155, and 0.25 d(-1), respectively). The result is much higher selenium concentrations in the bivalve than in the crustaceans. Stable isotope analyses show that this difference is propagated up the respective food webs in San Francisco Bay. Several predators of bivalves have tissue concentrations of selenium that exceed thresholds thought to be associated with teratogenesis or reproductive failure (liver Se >15 microg g(-1) dry weight). Deformities typical of selenium-induced teratogenesis were observed in one of these species. Concentrations of selenium in tissues of predators of zooplankton are less than the thresholds. Basic physiological and ecological processes can drive wide differences in exposure and effects among species, but such processes are rarely considered in traditional evaluations of contaminant impacts.     

Characterization of Tantalum–Titanium Powders with Universal Powder Bed (UPB) System for Electron Beam Melting Process

Russian Journal of Non-Ferrous Metals - Electron beam melting (EBM) is a powder bed fusion additive manufacturing (AM) technique that produces three-dimensional (3D) parts by fusing metallic...     

Shape selective cracking ofn-octane and 2,2,4-trimethylpentane over an alumina-pillared clay

A mixture ofn-octane (nC₈) and 2, 2, 4-trimethylpentane (224-TMP) was cracked over an alumina-pillared montmorillonite (Al-PILC) acid catalyst as a means of characterising its pore structure and shape selectivity. The shape selectivity of the catalyst was quantified by a time dependent parameter analogous to the constraint index, called the selectivity ratio (SR), and defined as log (fraction of nC₈ remaining)/log (fraction of 224-TMP remaining). The SR was measured over Al-PILC, a 0.16 wt% Pt loaded Al-PILC, a Y zeolite, and an amorphous silicaalumina. The SR was greater over Al-PILC compared with Y-zeolite even though the pore openings of the Al-PILC were of similar or larger size than those in the Y-zeolite. Doping AlPILC with Pt caused a large increase in the SR. As found with constraint index measurements, internal pore dimensions and reaction mechanisms appear to be the determinants of SR. However, SR is better capable of discriminating larger pore microporous materials.     

Visible Light Triggered CO2 Liberation from Silver Nanocrystals Incorporated Metal–Organic Frameworks

Widespread deployment of metal–organic frameworks (MOFs) for CO₂ capture remains challenging due to the great energy‐penalty associated with their regeneration. To overcome this challenge, a new type of photodynamic carbon capture material synthesized by incorporating Ag nanocrystals with UiO‐66 (Ag/UiO‐66) framework is presented. Upon the irradiation of visible light, Ag nanocrystals within the composites serve as “nanoheaters” to convert photon energy into thermal energy locally. Driven by such light‐induced localized heat (LLH), the adsorbed CO₂ within MOFs is remotely released. The CO₂ desorption capacity of such Ag/UiO‐66 composites can be readily regulated by control over their Ag contents and the applied light intensity. Up to 90.5% of CO₂ desorption is achieved under the investigated conditions. Distinct from the traditional light‐responsive MOFs for gas trigger release, currently developed LLH‐driven CO₂ release method not only offers a promising solution to the heat‐insulating nature of MOFs, but also demonstrates a potentially low energy method to remotely regenerate MOF adsorbents given the utilization of naturally abundant visible light as efficient stimulus.     

β-Caryophyllene Induces Apoptosis and Inhibits Angiogenesis in Colorectal Cancer Models

Beta-Caryophyllene (BCP), a naturally occurring sesquiterpene abundantly found in cloves, hops, and cannabis, is the active candidate of a relatively new group of vascular-inhibiting compounds that aim to block existing tumor blood vessels. Previously, we have reported the anti-cancer properties of BCP by utilizing a series of in-vitro anti-tumor-related assays using human colorectal carcinoma cells. The present study aimed to investigate the effects of BCP on in-vitro, ex-vivo, and in-vivo models of anti-angiogenic assays and evaluate its anti-cancer activity in xenograft tumor (both ectopic and orthotopic) mice models of human colorectal cancer. Computational structural analysis and an apoptosis antibody array were also performed to understand the molecular players underlying this effect. BCP exhibited strong anti-angiogenic activity by blocking the migration of endothelial cells, tube-like network formation, suppression of vascular endothelial growth factor (VEGF) secretion from human umbilical vein endothelial cells and sprouting of rat aorta microvessels. BCP has a probable binding at Site#0 on the surface of VEGFR2. Moreover, BCP significantly deformed the vascularization architecture compared to the negative control in a chick embryo chorioallantoic membrane assay. BCP showed a remarkable reduction in tumor size and fluorescence molecular tomography signal intensity in all the mice treated with BCP, in a dose-dependent relationship, in ectopic and orthotopic tumor xenograft models, respectively. The histological analysis of the tumor from BCP-treated mice revealed a clear reduction of the density of vascularization. In addition, BCP induced apoptosis through downregulation of HSP60, HTRA, survivin, and XIAP, along with the upregulation of p21 expressions. These results suggest that BCP acts at multiple stages of angiogenesis and could be used as a promising therapeutic candidate to halt the growth of colorectal tumor cells.