Hasil untuk "Environmental sciences"

A. Sedgwick, Luling Wu, Hai-Hao Han et al.

In this review we will explore recent advances in the design and application of excited-state intramolecular proton-transfer (ESIPT) based fluorescent probes. Fluorescence based sensors and imaging agents (probes) are important in biology, physiology, pharmacology, and environmental science for the selective detection of biologically and/or environmentally important species. The development of ESIPT-based fluorescence probes is particularly attractive due to their unique properties, which include a large Stokes shift, environmental sensitivity and potential for ratiometric sensing.

D. Leung, M. Boguniewicz, M. Howell et al.

F. Geels

K. Lewis

We are experiencing an antimicrobial resistance (AMR) crisis, brought on by the drying up of the antibiotic discovery pipeline and the resulting unchecked spread of resistant pathogens. Traditional methods of screening environmental isolates or compound libraries have not produced a new drug in over 30 years. Antibiotic discovery is uniquely difficult due to a highly restrictive penetration barrier and other mechanisms that allow bacteria to survive in the presence of toxic compounds. In this Perspective, we analyze the challenges facing discovery and discuss an emerging new platform for antibiotic discovery. The penetration barrier makes screening conventional synthetic compound libraries largely impractical, and actinomycetes, the main source of natural product compounds, have been overmined. The emerging platform is based on understanding the rules that guide the permeation of molecules into bacteria and on advances in microbiology, which enable us to identify and access attractive groups of secondary metabolite producers. Establishing this platform will enable reliable production of lead compounds to combat AMR.

Fan Ma, M. Hanna

J.R. Jensen

B. McGill, B. Enquist, E. Weiher et al.

B. Smit, J. Wandel

This paper reviews the concept of adaptation of human communities to global changes, especially climate change, in the context of adaptive capacity and vulnerability. It focuses on scholarship that contributes to practical implementation of adaptations at the community scale. In numerous social science fields, adaptations are considered as responses to risks associated with the interaction of environmental hazards and human vulnerability or adaptive capacity. In the climate change field, adaptation analyses have been undertaken for several distinct purposes. Impact assessments assume adaptations to estimate damages to longer term climate scenarios with and without adjustments. Evaluations of specified adaptation options aim to identify preferred measures. Vulnerability indices seek to provide relative vulnerability scores for countries, regions or communities. The main purpose of participatory vulnerability assessments is to identify adaptation strategies that are feasible and practical in communities. The distinctive features of adaptation analyses with this purpose are outlined, and common elements of this approach are described. Practical adaptation initiatives tend to focus on risks that are already problematic, climate is considered together with other environmental and social stresses, and adaptations are mostly integrated or mainstreamed into other resource management, disaster preparedness and sustainable development programs. r 2006 Elsevier Ltd. All rights reserved.

F. Fisher

C. Daughton, T. Ternes

During the last three decades, the impact of chemical pollution has focused almost exclusively on the conventional "priority" pollutants, especially those acutely toxic/carcinogenic pesticides and industrial intermediates displaying persistence in the environment. This spectrum of chemicals, however, is only one piece of the larger puzzle in "holistic" risk assessment. Another diverse group of bioactive chemicals receiving comparatively little attention as potential environmental pollutants includes the pharmaceuticals and active ingredients in personal care products (in this review collectively termed PPCPs), both human and veterinary, including not just prescription drugs and biologics, but also diagnostic agents, "nutraceuticals," fragrances, sun-screen agents, and numerous others. These compounds and their bioactive metabolites can be continually introduced to the aquatic environment as complex mixtures via a number of routes but primarily by both untreated and treated sewage. Aquatic pollution is particularly troublesome because aquatic organisms are captive to continual life-cycle, multigenerational exposure. The possibility for continual but undetectable or unnoticed effects on aquatic organisms is particularly worrisome because effects could accumulate so slowly that major change goes undetected until the cumulative level of these effects finally cascades to irreversible change--change that would otherwise be attributed to natural adaptation or ecologic succession. As opposed to the conventional, persistent priority pollutants, PPCPs need not be persistent if they are continually introduced to surface waters, even at low parts-per-trillion/parts-per-billion concentrations (ng-microg/L). Even though some PPCPs are extremely persistent and introduced to the environment in very high quantities and perhaps have already gained ubiquity worldwide, others could act as if they were persistent, simply because their continual infusion into the aquatic environment serves to sustain perpetual life-cycle exposures for aquatic organisms. This review attempts to synthesize the literature on environmental origin, distribution/occurrence, and effects and to catalyze a more focused discussion in the environmental science community.

S. Running, R. Nemani, F. Heinsch et al.

M. Kent, P. Coker

W Evan Rivers, J. Stribling, M. Barbour et al.

武彦 福島

J. Murray

F. Berkes

C. Freeman

I. Annis

I. Wilson

Frideni Yushandiana Putri G.F., Kusuma Nizar Angga, Winarko Ronny et al.

Gold (Au) and silver (Ag) are commonly co-extracted from low-sulphidation epithermal (LSE) ores by alkaline cyanidation, yet their dissolution behaviors often diverge despite close mineralogical association. This study investigates Au–Ag cyanidation in ore from the Mount Muro LSE deposit, Central Kalimantan, Indonesia, through integrated mineralogical characterization, diagnostic leaching, time-resolved cyanidation, residue analysis, and kinetic modeling. Diagnostic leaching indicates that ~80% of Au is cyanide-accessible at P₈₀ ≈ 75 μm, whereas only ~54% of Ag occurs in free-milling domains, with the remainder hosted in sulfide and Cu–Ag sulfosalt phases. Continuous cyanidation confirms this contrast: Au dissolves rapidly and reaches a plateau of ~87% recovery, while Ag extraction proceeds more gradually to ~78%. Residue analysis shows that unrecovered Au and Ag are concentrated in fine fractions (<38 μm), demonstrating control by mineralogical locking, partial passivation, and micro-scale diffusional barriers rather than reagent insufficiency. Shrinking Core Model diagnosis identifies mixed kinetic control for Au and diffusion-dominated control for Ag. Despite differing dominant mechanisms, kinetic model discrimination shows that both metals are best described by the Ling model, capturing non-linear, accessibility-controlled dissolution. These results highlight evolving surface accessibility as the primary control on cyanidation performance in mildly refractory LSE ores.