High-efficiency Bidirectional Buck-Boost Converter for Residential Energy Storage System

This paper proposes a bidirectional dc-dc converter for residential micro-grid applications. The proposed converter can operate over an input voltage range that overlaps the output voltage range. This converter uses two snubber capacitors to reduce the switch turn-off losses, a dc-blocking capacitor to reduce the input/output filter size, and a 1:1 transformer to reduce core loss. The windings of the transformer are connected in parallel and in reverse-coupled configuration to suppress magnetic flux swing in the core. Zero-voltage turn-on of the switch is achieved by operating the converter in discontinuous conduction mode. The experimental converter was designed to operate at a switching frequency of 40-210 kHz, an input voltage of 48 V, an output voltage of 36-60 V, and an output power of 50-500 W. The power conversion efficiency for boost conversion to 60 V was >= 98.3% in the entire power range. The efficiency for buck conversion to 36 V was >= 98.4% in the entire power range. The output voltage ripple at full load was <3.59 V-p.p for boost conversion (60 V) and 1.35 V-p.p for buck conversion (36 V) with the reduced input/output filter. The experimental results indicate that the proposed converter is well-suited to smart-grid energy storage systems that require high efficiency, small size, and overlapping input and output voltage ranges.11Ysciescopu

Facile Method to Prepare for the Ni2P Nanostructures with Controlled Crystallinity and Morphology as Anode Materials of Lithium-Ion Batteries

Conversion reaction materials (transition metal oxides, sulfides, phosphides, etc.) are attractive in the field of lithium-ion batteries because of their high theoretical capacity and low cost. However, the realization of these materials in lithium-ion batteries is impeded by large voltage hysteresis, high polarization, inferior cycle stability, rate capability, irreversible capacity loss in first cycling, and dramatic volume change during redox reactions. One method to overcome these problems is the introduction of amorphous materials. This work introduces a facile method to synthesize amorphous and crystalline dinickel phosphide (Ni2P) nanoparticle clusters with identical morphology and presents a direct comparison of the two materials as anode materials for rechargeable lithium-ion batteries. To assess the effect of crystallinity and hierarchical structure of nanomaterials, it is crucial to conserve other factors including size, morphology, and ligand of nanoparticles. Although it is rarely studied about synthetic methods of well-controlled Ni2P nanomaterials to meet the above criteria, we synthesized amorphous, crystalline Ni2P, and self-assembled Ni2P nanoparticle clusters via thermal decomposition of nickel-surfactant complex. Interestingly, simple modulation of the quantity of nickel acetylacetonate produced amorphous, crystalline, and self-assembled Ni2P nanoparticles. A 0.357 M nickel-trioctylphosphine (TOP) solution leads to a reaction temperature limitation (similar to 315 degrees C) by the nickel precursor, and crystalline Ni2P (c-Ni2P) nanoparticles clusters are generated. On the contrary, a lower concentration (0.1 M) does not accompany a temperature limitation and hence high reaction temperature (330 degrees C) can be exploited for the self-assembly of Ni2P (s-Ni2P) nanoparticle clusters. Amorphous Ni2P (a-Ni2P) nanoparticle clusters are generated with a high concentration (0.714 M) of nickel-TOP solution and a temperature limitation (similar to 290 degrees C). The a-Ni2P nanoparticle cluster electrode exhibits higher capacities and Coulombic efficiency than the electrode based on c-Ni2P nanoparticle clusters. In addition, the amorphous structure of Ni2P can reduce irreversible capacity and voltage hysteresis upon cycling. The amorphous morphology of Ni2P also improves the rate capability, resulting in superior performance to those of c-Ni2P nanoparticle clusters in terms of electrode performance

Novel PEMFC Cathodes Prepared by Pulse Deposition

A pulse electrodeposition method of preparing thin platinum catalyst layers for polymer electrolyte membrane fuel cell (PEMFC) cathodes has been developed through surface activation of the gas diffusion layer (GDL) by a wetting agent. The performance of the catalyst layer was optimized by wetting agent type, immersion time in the wetting agent, and pulse deposition parameters such as total charge density, peak current density, and duty cycle ratio. The Toff time played a more important role than the Ton time in determining the electrode characteristics such as high concentration of Pt, smaller particle size, and loading. Pt cathodes prepared using a peak current density of 400 mA/cm2 with a duty cycle of 10.7% and total charge density of 6 C/cm2 resulted in a thin platinum catalyst layer (1.92 µm) and uniformly distributed platinum nanoparticles (3–4 nm) on the GDL surface. Novel cathodes with Pt loading of 0.33 mg/cm2 prepared in the present study exhibited 746 mA/cm2 at 0.7 V

Antimicrobial peptide from Bacillus subtilis CSB138: characterization, killing kinetics, and synergistic potency

We studied the prospect of synergy between the antimicrobial peptide p138c and non-peptide antibiotics for increasing the potency and bacterial killing kinetics of these agents. The production of p138c was maximized in the late exponential growth phase of Bacillus subtilis CSB138. Purification of p138c resulted in a total of 4800 arbitrary units (AU) with 19.15-fold and 3.2% recovery. Peptide p138c was thermo-tolerant up to 50 &deg;C and stable at pH 5.8 to 11. The biochemical nature of p138c was determined by a bioassay, similar to tricine-SDS-PAGE, indicating inhibition at 3 kDa. The amino acid sequence of p138c was Gly-Leu-Glu-Glu-Thr-Val-Tyr-Ile-Tyr-Gly-Ala-Asn-Met-X-Ser. Potency and killing kinetics against vancomycin-resistant Staphylococcus aureus improved considerably when p138c was synergized with oxacillin, ampicillin, and penicillin G. The minimal inhibitory concentration (MIC) of p138c showed a 4-, 8-, and 16-fold improvement when p138c was combined with oxacillin, ampicillin, and penicillin G, respectively. The fractional inhibitory concentration index for the combination of p138c and oxacillin, ampicillin, and penicillin G was 0.3125, 0.25, and 0.09, respectively. Synergy with non-peptide antibiotics resulted in enhanced killing kinetics of p138c. Hence, the synergy between antimicrobial peptide and non-peptide antibiotics may enhance the potency and bacterial killing kinetics, providing more potent and rapidly acting agents for therapeutic use. [Int Microbiol 20(1):43-53 (2017)]Keywords: Bacillus subtilis &middot; antimicrobial peptides &middot; killing kinetic

Large‐Scale, Ultrapliable, and Free‐Standing Nanomembranes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97443/1/adma_201204619_sm_suppl.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97443/2/2167_ftp.pd

Resting-state EEG activity related to impulsivity in gambling disorder

Background and aims Impulsivity is a core feature of gambling disorder (GD) and is related to the treatment response. Thus, it is of interest to determine objective neurobiological markers associated with impulsivity in GD. We explored resting-state electroencephalographic (EEG) activity in patients with GD according to the degree of impulsivity. Methods In total, 109 GD subjects were divided into three groups according to Barratt impulsiveness scale-11 (BIS-11) scores: high (HI; 25th percentile of BIS-11 scores, n = 29), middle (MI; 26th–74th percentile, n = 57), and low-impulsivity (LI) groups (75th percentile, n = 23). We used generalized estimating equations to analyze differences in EEG absolute power considering group (HI, MI, and LI), brain region (frontal, central, and posterior), and hemisphere (left, midline, and right) for each frequency band (delta, theta, alpha, beta, and gamma). Results The results indicated that GD patients in the HI group showed decreased theta absolute power, and decreased alpha and beta absolute power in the left, right, particularly midline frontocentral regions. Discussion and conclusions This study is a novel attempt to reveal impulsive features in GD by neurophysiological methods. The results suggest different EEG patterns among GD patients according to the degree of impulsivity, raising the possibility of neurophysiological objective features in GD and helping clinicians in treating GD patients with impulsive features

Giant Magnetic Fluctuations at the Critical Endpoint in Insulating HoMnO3

Although abundant research has focused recently on the quantum criticality of itinerant magnets, critical phenomena of insulating magnets in the vicinity of critical endpoints (CEP's) have rarely been revealed. Here we observe an emergent CEP at 2.05 T and 2.2 K with a suppressed thermal conductivity and concomitant strong critical fluctuations evident via a divergent magnetic susceptibility (e.g., ????????(2.05 T,2.2 K)/????????(3 T,2.2 K)&#8776;23,500%, comparable to the critical opalescence in water) in the hexagonal insulating antiferromagnet HoMnO3. &#169; 2013 American Physical Society.open1