Widespread reliance on credit increasingly defines realities of economic citizenship in American society. This article theorizes the racial politics of credit expansion. It examines the federal ...initiative in the 1960s and ’70s to broaden financial access for poor renters in communities of color, which unintentionally sparked the rise of new state-level credit agencies. Drawing on historical evidence, much of it never used before, the author’s findings reveal the contentious politics at the heart of this policy shift. Doing so highlights the constitutive whiteness of credit and also illuminates how the project of expanding credit to marginalized groups tests the categorical seams of markets in the public imagination: such initiatives fuel racial contestation around taken-for-granted market rules, which draws governing officials toward increasingly speculative and convoluted financial instruments as a means of rule-bending subversion. Ultimately, this article sheds much-needed light on, and encourages further research into, the racial stratification of the state’s market-making power.
Bioenergy, derived from biomass and/or biological (or biomass-derived) waste residues, has been acknowledged as a sustainable and clean burning source of renewable energy with the potential to reduce ...our reliance on fossil fuels (such as oil and natural gas). However, many bioenergy processes require some form of pre-treatment and/or upgrading procedure for biomass to generate a modified residue with more suitable properties and render it more compatible with the specific energy conversion route chosen. Many of these pre-treatments (or upgrading procedures) involve some form of substantive heating of the biomass to achieve this modification. Microwave (MW) heating has attracted much attention in recent years due to the advantages associated with dielectric heating effects. These advantages include rapid and efficient heating in a controlled environment, increasing processing rates and substantially shortening reaction times by up to 80%. However, despite this interest, the growth of industrial MW heating applications for bioenergy production has been hindered by a lack of understanding of the fundamentals of the MW heating mechanism when applied to biomass and waste residues. This article presents a review of the current scientific literature associated with the application of microwave heating for both the pre-treatment and upgrading of various biomass feedstocks across different bioenergy conversion pathways including thermal and biochemical processes. The fundamentals behind microwave heating will be explained, as well as discussion of the imperative areas which require further research and development to bridge the gap between fundamental science in the laboratory and the successful application of this technology at a commercial scale.
The folded 3D structures of peptides and proteins provide excellent starting points for the design of synthetic molecules that mimic key epitopes (or surface patches) involved in protein−protein and ...protein−nucleic acid interactions. Protein epitope mimetics (PEMs) may recapitulate not only the structural and conformational properties of the target epitope but also their biological activities. By transferring the epitope from a recombinant to a synthetic scaffold that can be produced by parallel combinatorial methods, it is possible to optimize properties through iterative cycles of library synthesis and screening, and even to evolve new biological activities. One very interesting scaffold is found in β-hairpin motifs, which are used by many proteins to mediate molecular recognition events. This motif is readily amenable to PEM design, for example, by transplanting hairpin loop sequences from folded proteins onto hairpin-stabilizing templates, such as the dipeptide d-Pro-l-Pro. In addition, β-hairpin peptidomimetics can also be exploited to mimic other types of epitopes, such as those based on α-helical secondary structures. The size and shape of β-hairpin PEMs appear well suited for the design of inhibitors of both protein−protein and protein−nucleic acid interactions, endeavors that have so far proven difficult using small “drug-like” molecules. In recent work, it was shown that β-hairpin PEMs can be designed that mimic the canonical conformations of antibody hypervariable loops, suggesting that novel small-molecule antibody mimics may be feasible. Using naturally occurring peptides as starting points, β-hairpin mimetics have been discovered that possess antimicrobial activity, while others are potent inhibitors of the chemokine receptor CXCR4. β-Hairpin PEMs have also been designed and optimized that mimic an α-helical epitope in p53 and so block its interaction with HDM2. A crystal structure of one HDM2−mimetic complex revealed how the surface of the protein had adapted to the shape of the hairpin, thereby enhancing inhibitor affinity. Small folded RNA motifs also make interesting targets for inhibitor design. For example, β-hairpin mimetics have been designed and optimized that bind with high affinity and good selectivity to the TAR and RRE RNA motifs from HIV-1. Solution structures of the mimetics both free and bound to the RNA target provided some surprises, as well as an improved understanding of the mechanisms of binding. These mimetics represent still a relatively new family of RNA-binding molecules, but clearly one with potential for development into novel antiviral agents.
The paper reviews how the concept of sustainable development has played out in industrialized countries since 1987. It examines the theory and practice of sustainable development in the context of ...three criticisms (it is vague, attracts hypocrites and fosters delusions), and argues for an approach to sustainability that is integrative, is action-oriented, goes beyond technical fixes, incorporates a recognition of the social construction of sustainable development, and engages local communities in new ways. The paper concludes with a description of an approach to sustainability that attempts to incorporate these characteristics.
•Flocculants are divided into three groups: chemical, natural and grafted flocculants.•Methods of wastewater treatment: coagulation–flocculation and direct flocculation.•Flocculating efficiency of ...bio-flocculants is comparable to chemical flocculants.•Flocculating mechanisms: charge neutralisation, bridging and electrostatic patching.
Flocculation is an essential phenomenon in industrial wastewater treatment. Inorganic coagulants (salts of multivalent metals) are being commonly used due to its low cost and ease of use. However, their application is constrained with low flocculating efficiency and the presence of residue metal concentration in the treated water. Organic polymeric flocculants are widely used nowadays due to its remarkable ability to flocculate efficiently with low dosage. However, its application is associated with lack of biodegradability and dispersion of monomers residue in water that may represent a health hazard. Therefore, biopolymers based flocculants have been attracting wide interest of researchers because they have the advantages of biodegradability and environmental friendly. But, natural flocculants are needed in large dosage due to its moderate flocculating efficiency and shorter shelf life. Thus, in order to combine the best properties of both, synthetic polymers are grafted onto the backbone of natural polymers to obtain tailor-made grafted flocculants. This paper gives an overview of the development of different types of flocculants that were being investigated for treatment of industrial wastewater. Furthermore, their flocculation performance will be reviewed and the flocculation mechanism will be discussed.
Einstein's theory of general relativity states that clocks at different gravitational potentials tick at different rates relative to lab coordinates-an effect known as the gravitational redshift
. As ...fundamental probes of space and time, atomic clocks have long served to test this prediction at distance scales from 30 centimetres to thousands of kilometres
. Ultimately, clocks will enable the study of the union of general relativity and quantum mechanics once they become sensitive to the finite wavefunction of quantum objects oscillating in curved space-time. Towards this regime, we measure a linear frequency gradient consistent with the gravitational redshift within a single millimetre-scale sample of ultracold strontium. Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10
. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.
We conduct frequency comparisons between a state-of-the-art strontium optical lattice clock, a cryogenic crystalline silicon cavity, and a hydrogen maser to set new bounds on the coupling of ...ultralight dark matter to standard model particles and fields in the mass range of 10−16−10−21 eV. The key advantage of this two-part ratio comparison is the differential sensitivity to time variation of both the fine-structure constant and the electron mass, achieving a substantially improved limit on the moduli of ultralight dark matter, particularly at higher masses than typical atomic spectroscopic results. Furthermore, we demonstrate an extension of the search range to even higher masses by use of dynamical decoupling techniques. These results highlight the importance of using the best-performing atomic clocks for fundamental physics applications, as all-optical timescales are increasingly integrated with, and will eventually supplant, existing microwave timescales.
Conservation organizations are asked to be responsive to a number of ethical obligations beyond that of the conservation of biodiversity: the reduction of poverty, the imperative of social justice ...and cultural integrity, and the improvement in human livelihoods. Yet how a conservation project is designed and structured can negatively impact people’s access to resources, privilege one group of people over another, or protect some species at a cost to others. Ideological conflict among nature protectionists, advocates for indigenous people, those promoting a pro-poor agenda, and those seeking to move conservation into the economic mainstream has characterized the conservation debate. I argue that in practice, most conservation programs should adopt a pluralistic and pragmatic approach, adopting multiple goals and making decisions on the basis of what works. Choosing among approaches requires an appreciation of trade-offs, and consideration of biological, social, and cultural values. Ultimately conservation approaches must be sustainable – ecologically, culturally, socially, economically and politically – otherwise they will fail both practically and ethically.
Conformationally constrained peptidomimetics have been developed to mimic interfacial epitopes and target a wide selection of protein-protein interactions. ß-Hairpin mimetics based on constrained ...macrocyclic peptides have provided access to excellent structural mimics of ß-hairpin epitopes and found applications as interaction inhibitors in many areas of biology and medicinal chemistry. Recently, ß-hairpin peptidomimetics and naturally occurring ß-hairpin-shaped peptides have also been discovered with potent antimicrobial activity and novel mechanisms of action, targeting essential outer membrane protein (OMP) complexes in Gram-negative bacteria. This includes the Lpt complex, required for transporting LPS to the cell surface during OM biogenesis and the BAM complex that folds OMPs and inserts them into the OM bilayer. The Lpt complex is a macromolecular superstructure comprising seven different proteins (LptA-LptG) that spans the entire bacterial cell envelope, whereas the BAM complex is a folding machine comprising a ß-barrel OMP (BamA) and four different lipoproteins (BamB-BamE). Folded synthetic and natural ß-hairpin-shaped peptides appear well-suited for interacting with proteins within the Lpt and BAM complexes that are rich in ß-structure. Recent progress in identifying antibiotics targeting these complexes are reviewed here. Already a clinical candidate has been developed (murepavadin) that targets LptD, with potent antimicrobial activity specifically against pseudmonads. The ability of folded synthetic ß-hairpin epitope mimetics to interact with ß-barrel and ß-jellyroll domains in the Lpt and Bam complexes represent new avenues for antibiotic discovery, which may lead to the development of much needed new antimicrobials to combat the rise of drug-resistant pathogenic Gram-negative bacteria.
NG2-expressing glia (NG2 glia) are a uniformly distributed and mitotically active pool of cells in the central nervous system (CNS). In addition to serving as progenitors of myelinating ...oligodendrocytes, NG2 glia might also fulfill physiological roles in CNS homeostasis, although the mechanistic nature of such roles remains unclear. Here, we report that ablation of NG2 glia in the prefrontal cortex (PFC) of the adult brain causes deficits in excitatory glutamatergic neurotransmission and astrocytic extracellular glutamate uptake and induces depressive-like behaviors in mice. We show in parallel that chronic social stress causes NG2 glia density to decrease in areas critical to Major Depressive Disorder (MDD) pathophysiology at the time of symptom emergence in stress-susceptible mice. Finally, we demonstrate that loss of NG2 glial secretion of fibroblast growth factor 2 (FGF2) suffices to induce the same behavioral deficits. Our findings outline a pathway and role for NG2 glia in CNS homeostasis and mood disorders.
•NG2 glia loss affects the glutaminergic systems in the PFC•NG2 glia loss in the PFC induces behavioral deficits via loss of secreted FGF2•NG2 glia density is reduced in subjects with MDD and in susceptible mice after SDSP•Restoration of NG2 glia density rescues cellular and behavioral aberrations
Functional contribution of glia to the pathophysiology of mental disorders is poorly understood. Birey and colleagues describe a role for NG2 glial cell in mediating CNS homeostasis, the loss of which leads to the emergence of depressive-like behaviors in mice.
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