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At least 1,495 records · Page 83

Opportunities for Neutrino Physics at the Spallation Neutron Source: A White Paper

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this document, the product of a workshop at the SNS in May 2012, we describe this free, high-quality stopped-pion neutrino source and outline various physics that could be done using it. We describe without prioritization some specific experimental configurations that could address these physics topics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Accessing (Ba 1-x Sr x )Al 2 Si 2 O 8 :Eu Phosphors for Solid State White Lighting via Microwave-assisted Preparation: Tuning Emission Color by Coordination Environment

The preparation of Eu 2+ -substituted barium aluminum silicates is achieved using a rapid microwave-assisted preparation. The phase evolution of two BaAl 2 Si 2 O 8 :Eu 2+ polymorphs, the higher temperature hexagonal phase (hexacelsian), and the lower temperature monoclinic phase (celsian), is explored by varying the ramp time and soak time. This preparation method significantly reduces the reaction time needed to form these phases compared to conventional solid state routes. The luminescent properties of the two phases are identified under UV excitation with the hexagonal phase emitting in the UV region (λ em = 372 nm) and the monoclinic phase emitting in the blue region (λ em = 438 nm). The differences in optical properties of the two polymorphs are correlated to the coordination number and arrangement of the alkali earth site. The optical properties of the monoclinic phase can be further tuned through the substitution of Sr 2+ , forming the solid solution (Ba 1–x Sr x )Al 2 Si 2 O 8 :Eu 2+ . Changes in the crystal structure due to Sr 2+ substitution produce a surprising blue-shift in the emission spectrum, which is explained by a greater dispersion of bond lengths in the (Ba/Sr)–O polyhedra. The entire monoclinic solid solution exhibits excellent quantum yields of nearly 90 %, owing to the structural rigidity provided by the highly connected tetrahedral network.

Brgoch, Jakoah↗

Adipocyte-specific deficiency of Nfe2l1 disrupts plasticity of white adipose tissues and metabolic homeostasis in mice

Highlights: • Nfe2l1(f)-KO mice exhibit diminished subcutaneous adipose tissues. • Nfe2l1(f)-KO mice show severe adipocyte hypertrophy and adipose inflammation. • Nfe2l1(f)-KO mice develop glucose intolerance and insulin resistance. The maintenance of healthy adipose tissues is essential for efficient regulation of energy homeostasis. Nuclear factor-erythroid 2-related factor 1 (NFE2L1, also known as Nrf1), a CNC-bZIP protein, is a master regulator of the cellular adaptive response to stresses. To investigate the role of NFE2L1 in adipocytes, we bred a line of mice with adipocyte-specific Nfe2l1 knockout (Nfe2l1(f)-KO), and found that Nfe2l1(f)-KO mice exhibited a dramatically reduced subcutaneous adipose tissue (SAT) mass, insulin resistance, adipocyte hypertrophy, and severe adipose inflammation. Mechanistic studies revealed that Nfe2l1 deficiency may disturb the expression of lipolytic genes in adipocytes, leading to adipocyte hypertrophy followed by inflammation, pyroptosis, and insulin resistance. Our findings reveal a novel role for NFE2L1 in regulating adipose tissue plasticity and energy homeostasis.

60 APPLIED LIFE SCIENCES↗

Vitamin D receptor ligands attenuate the inflammatory profile of IL-1β-stimulated human white preadipocytes via modulating the NF-κB and unfolded protein response pathways

Highlights: • IL-1β enhances the inflammatory profile of preadipocytes by post-translationally modifying relA of the NF-κB pathway. • Vitamin D ligands inhibit expression of pro-inflammatory factors in IL-1β-stimulated preadipocytes by decreasing phosphorylation or increasing methylation of relA. • Vitamin D ligands reduce secretion of proinflammatory factors from IL-1β-stimulated preadipocytes by increasing eIF-2α phosphorylation in the UPR pathway. Metaflammation in adipose tissue, which is characterized by increased local gene expression and secretion of pro-inflammatory factors, may contribute to the increased risk of metabolic complications in obesity. It has been suggested that IL-1β might induce metaflammation in adipose tissue via modulating the NF-κB signaling pathway. In our study, the mRNA and secretion levels of major pro-inflammatory factors including IL (interleukin)-1β, IL-6, IL-8, MCP (monocyte chemoattractant protein)-1 and RANTES (regulated on activation, normal T cell expressed and secreted) were measured as indicators of the inflammatory profile. We herein showed that IL-1β could induce adipose tissue metaflammation by enhancing the inflammatory profile of preadipocytes. Moreover, IL-1β could enhance pro-inflammatory gene expression by increasing the phosphorylation or decreasing the methylation of relA (NF-κB p65) of the NF-κB signaling pathway. VDR (vitamin D receptor) ligands have been shown to have anti-inflammatory properties in adipocytes. Likewise, our study demonstrated that the inflammatory profile of IL-1β-stimulated preadipocytes is significantly attenuated by VDR ligands 1α,25(OH){sub 2}D{sub 3}, ZK159222 and ZK191785. Importantly, we showed that ZK159222 and ZK191785 could inhibit pro-inflammatory gene expression by decreasing the phosphorylation or increasing the methylation of relA. Furthermore, pro-inflammatory secretion could be reduced by 1α,25(OH){sub 2}D{sub 3}, ZK159222 and ZK191785 via increasing the phosphorylation of eIF (eukaryotic translation initiation factor)-2α of the UPR (unfolded protein response) pathway. These observations suggest that the VDR ligands may be considered potential anti-inflammatory treatments for obesity associated metabolic complications.

60 APPLIED LIFE SCIENCES↗

Impact of gamma-ray irradiation on hardened white Portland cement pastes exposed to atmosphere

Samples of matured hardened cement paste were exposed to an environment with gamma-ray irradiation, which induces a natural carbonation process. After a dose of approximately 5 x 10{sup 4} kGy, the physical properties, microstructure, and phase composition of the irradiated hardened cement paste samples are compared with those of reference samples exposed to an identical environment without gamma-ray irradiation. Experiments confirm that aragonite and vaterite are preferentially formed under irradiation and that the bending strength is dramatically increased after gamma-ray irradiation. Based on field-emission scanning electron microscopy observations, X-ray scattering profiles, and water vapor sorption isotherm data, it is concluded that vaterite formed on C–S–H plays a role in strengthening the structure of C–S–H via pseudomorphs.

36 MATERIALS SCIENCE↗