Magnetic, electronic, and electrochemical properties of high-voltage spinel cathodes for lithium-ion batteries

textLithium-ion technology has revolutionized the electronics and electric vehicle industry in the past two decades. First commercialized by Sony in 1991, the lithium-ion battery is composed of three main components: (i) the cathode, (ii) the anode, and (iii) the electrolyte. Graphitic carbon remains the most widely used anode material due to its low voltage vs. the Li/Li+ redox couple and high specific capacity. However, there are several popular cathode materials, including layered oxides, spinel oxides, and polyanion materials. In an effort to increase the energy density of lithium-ion batteries, much focus is given to improving the gravimetric charge capacity and the overall cell voltage. The latter must be accomplished by employing high-voltage cathodes, the most promising of which is the lithium manganese nickel oxide spinel with a specific capacity of 146 mAh/g and a redox voltage of 4.7 V vs. Li/Li+. However, there are still several problems with this material that must be understood and overcome in order to develop high-voltage spinel as a viable commercial cathode. Physical property measurements can reveal the underlying electronic and atomic interactions in the solid in order to better understand high-voltage spinel and its odd behavior. Novel magnetic techniques have been developed, which reliably indicate the degree of Mn-Ni ordering and quantitative determination of the concentration of the Mn3+ ion. Measurements of several physical properties as a function of lithium content were also undertaken to determine the effects of Mn-Ni ordering on the electronic conductivity and the importance of electron-ion interactions. In addition to understanding the physical properties of high voltage spinel, the understanding of the solid state chemistry and unique structure was utilized to realize a new full cell construction technique. The spinel structure offers a unique way to deal with first cycle irreversible capacity loss in full cells stemming from solid-electrolyte interphase (SEI) layer growth on the anode surface. To that end, a novel microwave-assisted chemical lithiation process was developed using non-toxic and air-stable chemicals. New composite anode chemistry was combined with a pre-lithiated spinel cathode to demonstrate the feasibility of this approach to realizing practical next-generation Li-ion cells.Materials Science and Engineerin

The Beck Initiative : training school-based mental health staff in cognitive therapy

A growing literature supports cognitive therapy (CT) as an efficacious treatment for youth struggling with emotional or behavioral problems. Recently, work in this area has extended the dissemination of CT to school-based settings. The current study has two aims: 1) to examine the development of therapists’ knowledge and skills in CT, an evidence-based approach to promoting student well-being, and 2) to examine patterns of narrative feedback provided to therapists participating in the program. As expected, school therapists trained in CT demonstrated significant gains in their knowledge of CT theory and in their demonstration of CT skills, with the majority of therapists surpassing the accepted threshold of competency in CT. In addition, an examination of feedback content suggested that narrative feedback provided to therapists most frequently consisted of positive feedback and instructions for future sessions. Suggestions for future research regarding dissemination of CT are discussed in light of increasing broad access to evidence based practices.peer-reviewe

2-Phenyl-3-(trimethyl­sil­yl)propan-1-aminium chloride

The title compound, C12H22NSi+·Cl−, contains two formula units in the asymmetric unit and is a hydro­chloride salt in which the amine N atom is protonated and the NH3 + group forms hydrogen bonds with the Cl− anion, forming a ribbon in the c-axis direction

2-(4-Hy­droxy­phen­yl)-3-(trimethyl­sil­yl)propanaminium chloride

In the title crystal structure, C12H22NOSi+·Cl−, anions and cations are linked via O—H⋯Cl, N—H⋯Cl and N—H⋯O hydrogen bonds to form a two-dimensional network parallel to (101). Within the hydrogen-bonded network, R 4 2(22) ring motifs are stacked along [010]

The impact of conjunctival flap method and drainage cannula diameter on bleb survival in the rabbit model

Purpose To examine the effect of cannula diameter and conjunctival flap method on bleb survival in rabbits undergoing cannula-based glaucoma filtration surgery (GFS). Methods Twelve New Zealand White rabbits underwent GFS in both eyes. The twenty-four eyes were divided into four groups. Two of the four groups (N = 12) received limbus-based con- junctival flaps (LBCF), and the other two (N = 12) received fornix-based conjunctival flaps (FBCF). Six FBCF rabbit eyes were implanted with 22-gauge drainage tubes, and the other six were implanted with 26-gauge tubes. Likewise, six LBCF rabbits received 22-gauge drainage tubes and six received 26-gauge tubes. Filtration blebs were evaluated every three days by a masked observer. Bleb failure was defined as the primary endpoint in this study and was recorded after two consecutive flat bleb evaluations. Results Group 1 (LBCF, 22- gauge cannula) had a mean bleb survival time (Mean ± SD) of 18.7 ± 2.9 days. Group 2 (LBCF, 26-gauge cannula) also had a mean bleb survival time of 18.7 ± 2.9 days. Group 3 (FBCF, 22-gauge cannula) had a mean bleb survival time of 19.2 ± 3.8 days. Group 4 (FBCF, 26-gauge cannula) had a mean bleb survival time of 19.7 ± 4.1 days. A 2-way analysis of variance showed that neither surgical approach nor cannula gauge made a statistically significant difference in bleb survival time (P = 0.634 and P = 0.874). Additionally, there was no significant interaction between cannula gauge and conjunctival flap approach (P = 0.874), suggesting that there was not a combination of drainage gauge and conjunctival flap method that produced superior bleb survival. Conclusion Limbus and fornix-based conjunctival flaps are equally effective in promoting bleb survival using both 22 and 26-gauge cannulas in the rabbit model. The 26-gauge drainage tube may be preferred because its smaller size facilitates the implantation process, reducing the risk of corneal contact

Genotype, haplotype and copy-number variation in worldwide human populations

Genome-wide patterns of variation across individuals provide a powerful source of data for uncovering the history of migration, range expansion, and adaptation of the human species. However, high-resolution surveys of variation in genotype, haplotype and copy number have generally focused on a small number of population groups(1-3). Here we report the analysis of high-quality genotypes at 525,910 single-nucleotide polymorphisms ( SNPs) and 396 copy-number-variable loci in a worldwide sample of 29 populations. Analysis of SNP genotypes yields strongly supported fine-scale inferences about population structure. Increasing linkage disequilibrium is observed with increasing geographic distance from Africa, as expected under a serial founder effect for the out-of-Africa spread of human populations. New approaches for haplotype analysis produce inferences about population structure that complement results based on unphased SNPs. Despite a difference from SNPs in the frequency spectrum of the copy-number variants (CNVs) detected-including a comparatively large number of CNVs in previously unexamined populations from Oceania and the Americas-the global distribution of CNVs largely accords with population structure analyses for SNP data sets of similar size. Our results produce new inferences about inter-population variation, support the utility of CNVs in human population-genetic research, and serve as a genomic resource for human-genetic studies in diverse worldwide populations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62552/1/nature06742.pd

A Meta-Analysis of Effects of Bt Crops on Honey Bees (Hymenoptera: Apidae)

L.) are the most important pollinators of many agricultural crops worldwide and are a key test species used in the tiered safety assessment of genetically engineered insect-resistant crops. There is concern that widespread planting of these transgenic crops could harm honey bee populations.We conducted a meta-analysis of 25 studies that independently assessed potential effects of Bt Cry proteins on honey bee survival (or mortality). Our results show that Bt Cry proteins used in genetically modified crops commercialized for control of lepidopteran and coleopteran pests do not negatively affect the survival of either honey bee larvae or adults in laboratory settings.Although the additional stresses that honey bees face in the field could, in principle, modify their susceptibility to Cry proteins or lead to indirect effects, our findings support safety assessments that have not detected any direct negative effects of Bt crops for this vital insect pollinator

Managing software engineers and their knowledge

This chapter begins by reviewing the history of software engineering as a profession, especially the so-called software crisis and responses to it, to help focus on what it is that software engineers do. This leads into a discussion of the areas in software engineering that are problematic as a basis for considering knowledge management issues. Some of the previous work on knowledge management in software engineering is then examined, much of it not actually going under a knowledge management title, but rather “learning” or “expertise”. The chapter goes on to consider the potential for knowledge management in software engineering and the different types of knowledge management solutions and strategies that might be adopted, and it touches on the crucial importance of cultural issues. It concludes with a list of challenges that knowledge management in software engineering needs to address