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energy such as wind and solar energy has attracted enormous interest for its significant roles in mitigating CO 2 emissions and reducing dependence on petrochemicals. [1,2] At the heart of the CO 2 conversion technology, electrocatalysts are needed to promote a critical reaction, CO 2 reduction reaction (CO 2 RR) that determines the efficiency and selectivity. To date, the electrocatalysts have confronted severe bottlenecks issue: poor selectivity about various accessory products in CO 2 conversion process, and loss of efficiency toward competing hydrogen evolution. [3] The former involves associated multielectron transfer process and is difficult to accurately control the reaction process by external conditions, [4] while the latter is mainly due to the fact that the equilibrium potentials for most of the CO 2 RR are very close to hydrogen evolution reaction (HER) toward undesirable side-products in aqueous electrolytes, which degrades the electrocatalytic performance during the CO 2 RR process. [5,6] Therefore, CO 2 RR is much more complex than other energy-related electrochemical reactions such as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and it is still a great challenge to design and synthesize electrocatalytic materials with higher product selectivity and catalytic activity for CO 2 RR.Among the electrocatalysts including metals oxides and metal-doped carbon materials, single-atom catalysts (SACs) represent an exciting class of catalysts with monodispersed metal catalytic centers and have emerged as the frontier science in both homogeneous and heterogeneous catalysis, including CO 2 conversion. [7][8][9][10] This type of catalysts contains M-N-C moiety with single atoms and is common in building metalorganic frameworks (MOFs), [11] covalent organic frameworks (COFs) [12] with transition metal macrocyclic clusters, such as porphyrin, phthalocyanine, and tetraazannulene, as well as metal-doped carbon materials [13] (e.g., graphene, carbon nanotubes, fullerene). In nature, the biomolecules, like chlorophyll (Mg-porphyrin) in leaves, and iron porphyrins in cytochrome c oxidase in blood cells, have similar structures as SACs, with special ability in photosynthesis and transforming CO 2 from cells with high efficiency and selectivity. [14] Through the selection of appropriate motifs, the construction principles of Direct conversion of CO 2 into carbon-neutral fuels or industrial chemicals holds a great promise for renewable energy storage and mitigation of greenhouse gas emission. However, experimentally finding an electrocatalyst for specific final products with high efficiency and high selectivity poses serious challenges due to multiple electron transfer, complicated intermediates, and numerous reaction pathways in electrocatalytic CO 2 reduction. Here, an intrinsic descriptor that correlates the catalytic activity with the topological, bonding, and electronic structures of catalytic centers on M-N-C based single-atom catalysts is discovered. The "volcano"-shaped relationships betwee...

Carbon nanomaterials are promising metal-free catalysts for energy conversion and storage, but the catalysts are usually developed via traditional trial-and-error methods. To rationally design and accelerate the search for the highly-efficient catalysts, it is necessary to establish design principles for the carbon-based catalysts. This review focuses on the theoretical analysis and material design of the metal-free carbon nanomaterials as efficient photo-/electro-catalysts to facilitate the critical chemical reactions in clean and sustainable energy technologies, including oxygen reduction reaction in fuel cells, oxygen evolution reaction in metal-air batteries, iodine reduction reaction in dye-sensitized solar cells, hydrogen evolution reaction in water splitting, and carbon dioxide reduction in artificial photosynthesis. Basic catalytic principles, computationally guided design approaches and intrinsic descriptors, catalytic material design strategies, and future directions are discussed for the rational design and synthesis of highly efficient carbon-based catalysts for clean energy technologies.

Schizophrenia (SZ) is a neuropsychiatric disorder that affects about 1% of the adult population. Numerous genes have been implicated in SZ susceptibility. MicroRNAs (miRNA) are small RNA molecules that regulate the translation of mRNAs via interactions with their 3' untranslated regions. Identification of known miRNA targets on all human genes indicated that miRNA-346 targets SZ susceptibility genes listed in the SchizophreniaGene database, twice as frequently than expected relative to other genes in the genome. The gene encoding this miRNA, miR-346, is located in intron 2 of the glutamate receptor ionotropic delta 1 (GRID1) gene, which has been previously implicated in SZ susceptibility. We used quantitative real-time PCR to determine the expression levels of miR-346 and GRID1 using brain RNA samples from the Stanley Array Collection, Stanley Medical Research Institute. Expression of both miR-346 and GRID1 is lower in SZ patients than that in normal controls (P=0.017 and 0.086, respectively). However, the expression of miR-346 and GRID1 is less correlated in SZ patients than in bipolar patients or in normal controls. This study implicates the importance of a miRNA in SZ.

Localized surface plasmons (LSPs) in metal nanostructures have attracted much attentionfor their role in generating non-equilibrium hot carriers (HCs) for photochemistry 1-3 , photodetection 4,5 and photoluminescence 6 . In addition to optical excitation, LSPs and HC dynamics can be driven electrically via inelastic tunneling. LSP-mediated light emission in tunnel junctions 7-13 commonly features photon energies below the threshold set by the applied voltage bias. Recent work [14][15][16][17][18] has reported photon energies significantly above that threshold, while the underlying physical origin remains elusive. Proposed mechanisms include higher-order electron-plasmon and electron-electron interactions 15,17-20 , and blackbody radiation of hot electrons 16,21 . We report measurements of light emission in tunnel junctions of different plasmonic materials and reveal that HCs generated by nonradiative decay of electrically excited plasmons play a key role in above-threshold light emission. We observed the crossover from above-to below-threshold light emission regime by controlling the tunneling current. There is a giant material dependence of the photon yield, as much as four orders of magnitude, much greater than the plasmon-enhanced radiative efficiency of the tunneling gap. The spectral features of light emission are consistent with a proposed mechanism that incorporates the plasmonic field enhancement and a non-equilibrium HC distribution parametrized by a bias-dependent Boltzmann factor. The effective temperatures of HCs are found to correlate with the bias voltage, rather than the dissipated electrical power. Electrically driven HC generation (above 2000 K under modest voltage) and plasmon-enhanced light emission could open new strategies for chemistry, optoelectronics and quantum optics.Electrically driven light emission from tunnel junctions is of great interest for a variety of technologies requiring efficient optoelectronic integration and conversion at the nanoscale, such

Synopsis Changes in metabolic processes play a critical role in the survival or death of cells subjected to various stresses. Here, we have investigated the effects of endoplasmic reticulum (ER) stress on cellular metabolism. A major difficulty in studying metabolic responses to ER stress is that ER stress normally leads to apoptosis and metabolic changes observed in dying cells may be misleading. Therefore, we have used IL-3-dependent Bak−/− Bax−/− hematopoietic cells which do not die in the presence of the ER stress-inducing drug, tunicamycin. Tunicamycin-treated Bak−/−Bax−/− cells remain viable but cease growth, arresting in G1 and undergoing autophagy in the absence of apoptosis. In these cells we used NMR-based stable isotope resolved metabolomics (SIRM) to determine the metabolic effects of tunicamycin. Glucose was found to be the major carbon source for energy production and anabolic metabolism. Following tunicamycin exposure, glucose uptake and lactate production are greatly reduced. Decreased 13C labeling in several cellular metabolites suggests that mitochondrial function in cells undergoing ER stress is compromised. Consistent with this, mitochondrial membrane potential, oxygen consumption, and cellular ATP level are much lower compared with untreated cells. Importantly, the effects of tunicamycin on cellular metabolic processes may be related to a reduction of cell surface Glut-1 levels which, in turn, may reflect decreased Akt signaling. These results suggest that ER stress exerts profound effects on several central metabolic processes which may help explain cell death arising from ER stress in normal cells.

Almost 20 years ago, Emami et al. presented a comprehensive set of dose tolerance limits for normal tissue organs to therapeutic radiation, which has proven essential to the field of radiation oncology. The paradigm of stereotactic body radiotherapy (SBRT) has dramatically different dosing schemes but, to date, there has still been no comprehensive set of SBRT normal organ dose tolerance limits. As an initial step toward that goal, we performed an extensive review of the literature to compare dose limits utilized and reported in existing publications. The impact on dose tolerance limits of some key aspects of the methods and materials of the various authors is discussed. We have organized a table of 500 dose tolerance limits of normal structures for SBRT. We still observed several dose limits that are unknown or not validated. Data for SBRT dose tolerance limits are still preliminary and further clinical trials and validation are required. This manuscript presents an extensive collection of normal organ dose tolerance limits to facilitate both clinical application and further research.PACS numbers: 87.53.Ly, 87.55.dk

This paper proposes a sequencing algorithm for intensity-modulated radiation therapy with a multileaf collimator in the static mode. The algorithm aims to minimize the number of segments in a delivery sequence. For a machine with a long verification and recording overhead time (e.g., 15 s per segment), minimizing the number of segments is equivalent to minimizing the delivery time. The proposed new algorithm is based on checking numerous candidates for a segment and selecting the candidate that results in a residual intensity matrix with the least complexity. When there is more than one candidate resulting in the same complexity, the candidate with the largest size is selected. The complexity of an intensity matrix is measured in the new algorithm in terms of the number of segments in the delivery sequence obtained by using a published algorithm. The beam delivery efficiency of the proposed algorithm and the influence of different published algorithms used to calculate the complexity of an intensity matrix were tested with clinical intensity-modulated beams. The results show that no matter which published algorithm is used to calculate the complexity of an intensity matrix, the sequence generated by the algorithm proposed here is always more efficient than that generated by the published algorithm itself. The results also show that the algorithm used to calculate the complexity of an intensity matrix affects the efficiency of beam delivery. The delivery sequences are frequently most efficient when the algorithm of Bortfeld et al. is used to calculate the complexity of an intensity matrix. Because no single variation is most efficient for all beams tested, we suggest implementing multiple variations of our algorithm.