cssi/SciSciGPT-SciSciNet huggingface dataset:
Tribomechanical Properties of Ion Implanted Metals

A review of tribomechanical studies supported by surface analysis finds ion implantation capable of increasing the sliding wear resistance of ion implanted metals in two ways. First, it can reduce friction by modifying the surface composition (e.g. Ti+ into steel) or by promoting the growth of low friction oxide layers (e.g. N into Ti). Second, it can modify the subsurface composition and structure to resist fracture and debris formation. These modifications harden the surface, change its work-hardening behavior and/or increase residual stresses. Microindentation hardness measurements indicate that many but not all of the wear resistant surfaces are hardened by implantation; thus, surface hardness is a contributing but not necessarily a controlling factor in wear resistance. These mechanisms of wear reduction and the chemical and microstructural modifications responsible for them are discussed. Evidence for wear reduction through the migration of N during wear is critically reviewed. It is concluded that the principal benefit of ion implantation is to prevent or delay the formation of wear particles, thereby changing the wear mode during run-in and permitting metals to reach load-carrying capacities up to their elastic limits.
A Conceptual Change Model for Teaching Heat Energy, Heat Transfer and Insulation

This study examines the existing knowledge that pre-service elementary teachers (PSETs) have regarding heat energy, heat transfer and insulation. The PSETs' knowledge of heat energy was initially assessed by using an activity: determining which container would be best to keep hot water warm for the longest period of time. Results showed that PSETs could not explain the concept of insulation and heat transfer. Moreover, they held the misconception that a container deemed best to keep water warm would not be the best container to keep ice cream cold. To reconcile the misconceptions of PSETs, the researcher used the ED3U Conceptual Change Model (McComas, 1995) integrated with Posner, Strike, Hewson and Gertzog's (1982) conditions for accommodations for the designed instruction and discussions. Results show PSETs can understand the concepts better when analogy and daily life experiences are used.
Analyzing Path Dependence: Lessons from the Social Sciences

The study of path dependence has become a central research area in the disciplines of sociology and political science. These disciplines build on many insights initially formulated by economists. At the same time, however, soci ologists and political scientists offer their own distinctive contributions, some of which challenge the core assumptions of economics. In addition, they apply ideas of path dependence to the study of political and social outcomes that are not usually addressed in field of economics.
Physical properties and equations

As a natural science, the variability of river processes must be examined through the measurement of physical parameters. This chapter first describes dimensions and units (Section 2.1), physical properties of water (Section 2.2), and sediment (Section 2.3). The equations governing the motion of water and sediment from upland areas to oceans include kinematics of flow (Section 2.4), the equation of continuity (Section 2.5), the equation of motion (Section 2.6), and the concept of hydraulic and energy grade lines (Section 2.7). In this chapter and in the rest of the book, a solid diamond (♦) denotes equations and problems of particular significance. Problems with a double diamond (♦♦) are considered most important. Dimensions and units Physical properties are usually expressed in terms of the following fundamental dimensions: mass ( M ), length ( L ), time ( T ), and temperature ( T °). Throughout the text, the unit of mass is preferred to the corresponding unit of force. The fundamental dimensions are measurable parameters that can be quantified in fundamental units. In the SI system of units, the fundamental units of mass, length, time, and temperature are the kilogram (kg), the meter (m), the second (s), and degrees Kelvin (°K). Alternatively, the Celsius scale (°C) is commonly preferred because it refers to the freezing point of water at 0°C and the boiling point at 100°C. A Newton (N) is defined as the force required for accelerating 1 kg at 1 m/s 2 .
Propiedades emergentes: un reto para el químico intuitivo

En los ultimos anos varios autores han sugerido que una gran proporcion de las concepciones alternativas de los estudiantes de ciencias son el resultado de la aplicacion de razonamiento guiado por la intuicion o el sentido comun (Driver, Guesne, y Tiberghien, 1985; Driver et al., 1994; Viennot, 2001; Talanquer, 2002, 2005, 2006). Este tipo de razonamiento se basa en una serie de suposiciones sobre la naturaleza del mundo que nos rodea, y en el uso de estrategias de razonamiento que simplifican la toma de decisiones y la construccion de inferencias con base en la informacion disponible (Pozo y Gomez-Crespo, 1998; Furio y Furio, 2000; Campanario y Otero, 2000; de Cudmani, Pesa y Salinas, 2000; Hilton, 2002).
Everyone else is doing it (I think): The power of perception in fat talk

Fat talk (FT) involves critiquing one's own appearance in social conversations. Although peers are known to prompt FT behavior, there has been little exploration of the influence of mothers and research has not distinguished between self-reported FT and perceptions of FT. This study addresses this research gap by investigating the relationships between participants' FT and corresponding FT of both self-reported and perceived FT of their mothers and friends. A sample of 120 undergraduate women, along with their mothers and friends, reported their FT behavior. Hierarchical multiple regression analyses showed that friend-reported (but not mother-reported) FT and the daughters' perceived FT of both friends and mothers were significant predictors of daughter FT. However, daughters' perceptions of their friends' and mothers' FT predicted a significantly larger portion of variance than self-reported FT of friends and mothers. These results are important to consider when examining potential influences on the development of FT behavior.
Oxidation Adjacent to C X Bonds by Dehydrogenation

α,β-Unsaturated carbonyl compounds are versatile intermediates in the synthesis of pharmaceuticals and biologically active compounds. This chapter summarizes different oxidation methods available for dehydrogenation adjacent to carbonyl groups to access α,β-unsaturated carbonyl compounds. Historically important stoichiometric methods include sequential halogenation/dehydrohalogenation, elimination reactions that use sulfur and selenium reagents, and dichlorodicyanoquinone (DDQ)-mediated dehydrogenation. The use of hypervalent iodine reagents, such as 2-iodoxybenzoic acid (IBX), in α,β-dehydrogenation reactions has grown significantly, as have catalytic dehydrogenation methods, such as Pd-catalyzed methods capable of O 2 or other desirable stoichiometric oxidants. An overview of each of these methods is presented, together with selected synthetic applications. The relative merits of the individual methods are also considered.
How can a strong currency or drop in oil prices raise inflation and the black-market premium?

Abstract Based on the case of Venezuela, an oil exporter with a multiple exchange rate regime, this paper explains two counterintuitive phenomena. First, a fall in oil revenue can drive a steep rise in inflation by reducing foreign exchange for imports and raising the fiscal deficit financed by money growth. Second, when foreign exchange is rationed, a devaluation of the official exchange rate could produce a transitory fall in inflation by reducing the fiscal deficit and subsidies for buying foreign exchange. The paper also shows that the black market exchange rate can be rising far faster than overall inflation if it is driven by prices in the most distorted goods markets. The channels emphasized in this paper for determining inflation and the black market exchange rate are novel in the literature and may provide avenues of future research on commodity exporters and foreign exchange constraints.
Heterogeneous Computing Meets Near-Memory Acceleration and High-Level Synthesis in the Post-Moore Era

As the trends driven by Moore’s law come to an end, increased heterogeneity at all levels of computing is required to deliver the computing performance needed for emerging applications, leading to the proliferation of various application- or domain-specific accelerators. This in turn demands more memory bandwidth, as heterogeneous computing with accelerators consumes data at a much higher rate than traditional homogeneous computing, limiting the computing performance. To tackle this challenge, this article presents a conceptual near-memory acceleration architecture; demonstrates its practicality and plausibility using a recent experimental platform from IBM, as well as its potential impact on performance and energy efficiency; and discusses the need for adopting a high-level synthesis approach for such a near-memory acceleration architecture. Subsequently, this article concludes with future research directions for broad adoption of near-memory acceleration.
Selfies as postfeminist pedagogy: the production of traditional femininity in the US South

This article describes a study of selfies posted on Instagram by a group of predominantly white, college women at a large public university in the US South. Selfies are used as data to explore how ...
CHAPTER TWO – Some Tools of the Economist

Publisher Summary This chapter discusses the varied viewpoints of economists. Economists have difficulty in providing a satisfactory short definition of their subject. Some economists see economic processes constantly moving toward a state of equilibrium, while others see a constant tendency toward disequilibrium—a series of booms and busts until, in the final bust, capitalism itself would collapse. Mainstream contemporary economists try to escape such grand-scale rhetoric or myth-making, whether the myth is Smith's Invisible Hand of the Market or Marx's Class Struggle. They seek a more humble, less ideological economics. They see economies as an orderly way of explaining and resolving the disparities between human wants and scarce resources, or between greedy man and stingy nature. Given that basic fact about the human condition, people constantly face the problem of choice. Some economists feel that the backlog of past economic titans is fast diminishing and that economics itself is on a declining curve. Yet it might be too soon to despair. New sets of problems are coming along, and new breakthroughs are desperately needed on old problems.
Reflections on the Transition from Practice to Academia … the Nuts and Bolts

ABSTRACT This paper builds on the self-reflections reported earlier by David E. Stout about what he has learned (thus far) about being an accounting academic (Stout 2016). As the title implies, thi...
Factorization of Operators with Angularly Constrained Spectra

For arbitrary angular sectors W1 and W2 of the complex plane, we characterize AB : F(A) ⊂ W1. and F(B) ⊂ W2. This encompasses a number of classical results, such as Lyapunov theorems.
Human trabecular meshwork cell survival is dependent on perfusion rate

Purpose. To determine whether suppression of flow may be detrimental to trabecular cell survival and to the morphologic characteristics of the trabecular meshwork. Methods. The anterior segments of normal human eye bank eyes were placed in perfusion organ culture. The effect of various perfusion rates of culture medium, and of the constant flow and constant pressure methods of delivery of culture medium, were studied. Trabecular cell survival was determined by quantitation of cell nuclei in histologic sections and by morphologic observation. Results. Trabecular meshworks with perfusion rates of 1 //1/minute and higher had significantly more trabecular cells than meshworks with lower perfusion rates. A significant loss of trabecular cells was found in meshworks cultured with the constant pressure technique when compared with fellow eyes cultured with the constant flow of medium. Those constant pressure cultured meshworks with surviving cells had higher flow rates than those with necrotic cells. Conclusions. A minimum perfusion rate of 1 //1/minute is required for trabecular cell survival in perfusion organ culture. Constant pressure perfusion of medium is unsuccessful in maintaining trabecular cells in longterm culture if low perfusion rates occur. Constant flow appears to mimic the in vivo situation more closely. Invest Ophthalmol Vis Sci. 1996; 37:1204-1208.
The Problem of Relevant Detail

In recent years, welcome attention has been directed to population structure in mathematical models, improving substantially upon the overly aggregated characterizations of classical interest. This conference, in honor of Kenneth Cooke and his contributions to theories involving age structure, social structure, and delays, is testament to the modern trend, and to the recognition that simplistic theories that ignore population structure often are seriously flawed in their predictions.
A Groundless Clash of Freedoms?: The Religious Freedom of the Religiously Affiliated University and the Freedom of Faculty to Organize Under the NLRA

This article deals with the clash between faculty, especially adjunct faculty, wishing to use the processes of the National Labor Relations Board to organize at religiously affiliated universities and the objection of some of those universities who claim that the NLRB will violate their religious freedom under the Religion Clauses of the First Amendment and/or the Religious Freedom Restoration Act. This objection is based on the Supreme Court’s opinion in NLRB v. Catholic Bishop of Chicago where the Court invoked the “avoidance” doctrine to avoid deciding the First Amendment issues by deciding that Congress did not intend the NLRB to have jurisdiction over high schools operated by a church and where religious authority was pervasive. This objection, supported by two divided Circuits, wants to extend this “avoidance” mechanism to religiously affiliated universities where there is no such church authority and no pervasive religious atmosphere. The NLRB’s Pacific Lutheran University opinion seeks to preserve its jurisdiction in such cases. The effective right of many thousands of professors to organize is at issue. This article criticizes this extension of the avoidance doctrine as an evasion of a court’s duty to say what the law is and examines, on the merits, the constitutional and RFRA claims to show that the exercise of NLRB jurisdiction will in fact neither violate the Religion Clauses nor the RFRA.
Increasing dietary nitrate has no effects on bone loss in ovariectomized rats

ScopeEvidence suggests a diet rich in fruits and vegetables reduce bone loss in older adults, although the specific compounds responsible are not known. The objective of the present study was to in...
Stable Genetic Transformation and Heterologous Expression in the Nitrogen-fixing Plant Endosymbiont Frankia alni ACN14a

Abstract Genus Frankia is comprised primarily of nitrogen-fixing actinobacteria that form root nodule symbioses with a group of hosts known as the actinorhizal plants. These plants are evolutionarily closely related to the legumes, which are nodulated by the rhizobia. Both host groups utilize homologs of nodulation genes for root-nodule symbiosis, derived from common plant ancestors. However the corresponding endosymbionts, Frankia and the rhizobia, are distantly related groups of bacteria, leading to questions of their symbiotic mechanisms and evolutionary history. To date, a stable system of genetic transformation has been lacking in Frankia. Here, we report the successful electrotransformation of Frankia alni ACN14a, by means of replicating plasmids expressing chloramphenicol-resistance for selection, and the use of GFP as a marker of gene expression. We have identified type IV methyl-directed restriction systems, highly-expressed in a range of actinobacteria, as a likely barrier to Frankia transformation and circumvented this barrier by using unmethylated plasmids, which allowed the transformation of F. alni as well as the maintenance of the plasmid. During nitrogen limitation, Frankia differentiates into two cell types: the vegetative hyphae and nitrogen-fixing vesicles. When the plasmid transformation system was used with expression of egfp under the control of the nif gene cluster promoter, it was possible to demonstrate by fluorescence imaging the expression of nitrogen fixation in vesicles but not hyphae in nitrogen-limited culture. Importance To date, the study of Frankia-actinorhizal symbioses has been complicated by the lack of genetic tools for manipulation of Frankia, especially stable genetic transformation. The transformation system reported here, particularly coupled with marker genes, can be used to differentiate patterns of gene expression between Frankia hyphae and vesicles in symbiosis or in free-living conditions. This will enable deeper comparisons between Frankia-actinorhizal symbioses and rhizobia-legume symbioses in terms of molecular signaling and metabolic exchange that will broaden understanding of the evolution of these symbioses and potentially make possible their application in agriculture. The development of transformation methods will allow further down-stream applications including gene knock-outs and complementation that will, in turn, open up a much broader range of experiments into Frankia and its symbioses.
On the Description of Rheological Properties of Viscoelastic Continua, II. Proof that Oldroyd's 1950 Formalism Includes All 'Simple Fluids'.

It is proved that the following two classes of idealized incompressible materials are identical: (i) materials for which theCartesian extra-stress tensor is expressible as a one-particle functional of theCartesian deformation gradient tensor subject to a ‘material objectivity’ condition; (ii) materials for which the contravariant body extra-stress tensor is expressible as an isotropic one-particle functional of the covariant body metric tensor. From the close relationship of the body tensor formalism (ii) to the convected-component formalism ofOldroyd (discussed in paper I) it follows that all ‘Simple Fluids’ (i) are included inOldroyds formalism.
Bullying Victimization as a Strain: Examining Changes in Bullying Victimization and Delinquency among Korean Students from a Developmental General Strain Theory Perspective:

Objectives:Using a developmental extension of Agnew’s general strain theory (GST), the current study aims to assess the within-individual associations between bullying victimization and delinquency...
The effects of common structural variants on 3D chromatin structure.

Three-dimensional spatial organization of chromosomes is defined by highly self-interacting regions 0.1–1 Mb in size termed Topological Associating Domains (TADs). Genetic factors that explain dynamic variation in TAD structure are not understood. We hypothesize that common structural variation (SV) in the human population can disrupt regulatory sequences and thereby influence TAD formation. To determine the effects of SVs on 3D chromatin organization, we performed chromosome conformation capture sequencing (Hi-C) of lymphoblastoid cell lines from 19 subjects for which SVs had been previously characterized in the 1000 genomes project. We tested the effects of common deletion polymorphisms on TAD structure by linear regression analysis of nearby quantitative chromatin interactions (contacts) within 240 kb of the deletion, and we specifically tested the hypothesis that deletions at TAD boundaries (TBs) could result in large-scale alterations in chromatin conformation. Large (> 10 kb) deletions had significant effects on long-range chromatin interactions. Deletions were associated with increased contacts that span the deleted region and this effect was driven by large deletions that were not located within a TAD boundary (nonTB). Some deletions at TBs, including a 80 kb deletion of the genes CFHR1 and CFHR3, had detectable effects on chromatin contacts. However for TB deletions overall, we did not detect a pattern of effects that was consistent in magnitude or direction. Large inversions in the population had a distinguishable signature characterized by a rearrangement of contacts that span its breakpoints. Our study demonstrates that common SVs in the population impact long-range chromatin structure, and deletions and inversions have distinct signatures. However, the effects that we observe are subtle and variable between loci. Genome-wide analysis of chromatin conformation in large cohorts will be needed to quantify the influence of common SVs on chromatin structure.
The distributions of low birth weight rates and progesterone utilization rates during early -pregnancy in patients with different types of hypospadias

Objectives Our clinical trial started around the "two-hit" hypothesis,compared and an-alyzedthe low birth weight rates and progesterone utilization rates during early-pregnancy in patients with different types of hypospadias,because of "low birth weight" and " progesterone utilization during early pregnancy" are reasonable representations of "gene susceptibility" and "endocrine disruptor",so to discuss the etiology of hypospadias through this way.Methods According to the information from the registration forms of 97 boys firstly enrolled between May 2012 to December 2013 at the urological department of Soochow University affiliated children's hospital,and all these patients had met criteria of this trial,we divided them in to different groups due to the position of urethral orifice,generating the data of low birth weight rates and progesterone utilization rates in each group,and then used SPSS statistical software to do chi-square test and Kendall,Spearman rank correlation analysis.Results Pearson X2 =12.160,P ＜ 0.05 could confirm that there existed a differential distribution of low birth weight rates in groups with different types of hypospadias from the aspect of statistics,π =0.332,P ＜ 0.01 ; rs =0.350,P ≤0.01,could confirm that there existed a rank correlation of low birth weight rates in groups with different types of hypospadias from the aspect of statistics,which was the higher rate in the group,the severer of the patients in it ; Pearson X2 =11.004,P ＜ 0.05,could confirm that there existed a differential distribution of progesterone utilization rates in groups with different types of hypospadias from the aspect of statistics,π =0.304,P ＜ 0.01 ; rs =0.320,P ＜ 0.01,could confirm that there existed a rank correlation of progesterone utilization rates in groups with different types of hypospadias from the aspect of statistics,which was the higher rate in the group,the severer of the patients in it.Conclusions The existing differential distribution and rank correlation of low birth weight rates in groups with different types of hypospadias elucidated the first part of the "two-hit" hypothesis,which is that hypospadias needs "gene susceptibility" ; The existing differential distribution and rank correlation of progesterone utilization during early pregnancy in groups with different types of hypospadias elucidated the second part of the "two-hit" hypothesis,which is that besides gene susceptibility,hypospadias also needs particular environments exposure during the early stage of human embryonic development. Key words: Hypospadias ; Birth Weight ; Progesterone
Detection of the thietane precursor in the UVA formation of the DNA 6-4 photoadduct.

Notwithstanding the central biological role of the (6-4) photoadduct in the induction of skin cancer by sunlight, crucial mechanistic details about its formation have evaded characterization despite efforts spanning more than half a century. 4-Thiothymidine (4tT) has been widely used as an important model system to study its mechanism of formation, but the excited-state precursor, the intermediate species, and the time scale leading to the formation of the (6-4) photoadduct have remained elusive. Herein, steady-state and time-resolved spectroscopic techniques are combined with new and reported quantum-chemical calculations to demonstrate the excited state leading to the formation of the thietane intermediate, its rate, and the formation of the (6-4) photoadduct using the 5’-TT(4tT)T(4tT)TT-3’ DNA oligonucleotide. Efficient, sub-1 ps intersystem crossing leads to the population of a triplet minimum of the thietane intermediate in as short as 3 ps, which intersystem crosses to its ground state and rearranges to form the (6-4) photoadduct. The mechanisms of formation of the (6-4) photoproducts in DNA damage by sunlight is still debated. Here the authors show, by optical spectroscopies and computations, the details of the formation of a (6-4) photoadduct via the thietane intermediate in a single-stranded DNA oligonucleotide.
Detection of presymptomatic Alzheimer's disease through breath biomarkers.

Introduction Novel sensors were developed to detect exhaled volatile organic compounds to aid in the diagnosis of mild cognitive impairment associated with early stage Alzheimer's disease (AD). The sensors were sensitive to a rat model that combined the human apolipoprotein E (APOE)4 gene with aging and the Western diet. Methods Gas sensors fabricated from molecularly imprinted polymer-graphene were engineered to react with alkanes and small fatty acids associated with lipid peroxidation. With a detection sensitivity in parts per trillion the sensors were tested against the breath of wild-type and APOE4 male rats. Resting state BOLD functional connectivity was used to assess hippocampal function. Results Only APOE4 rats, and not wild-type controls, tested positive to several small hydrocarbons and presented with reduced functional coupling in hippocampal circuitry. Discussion These results are proof-of-concept toward the development of sensors that can be used as breath detectors in the diagnosis, prognosis, and treatment of presymptomatic AD.
Estimates of Workload Associated With Suicide Risk Alerts After Implementation of Risk-Prediction Model.

This cohort study attempts to validate the Mental Health Research Network suicide risk–prediction model and estimate associated workloads.
Dermoscopy image analysis in the age of deep learning

Dermoscopy is a non-invasive skin imaging technique that permits visualization of features of pigmented melanocytic neoplasms that are not discernable by examination with the naked eye. While studies on the automated analysis of dermoscopy images date back to the mid-1990s, because of various factors (lack of publicly available datasets, open-source software, computational power, etc.), the field progressed rather slowly in its first two decades. With the release of a large public dataset by the International Skin Imaging Collaboration in 2016, development of open-source software for convolutional neural networks, and the availability of inexpensive graphics processing units, dermoscopy image analysis has recently become a very active research field. In this talk, I will first present a historical overview of dermoscopy image analysis and then discuss the latest developments in this field that were prompted by the deep learning revolution.
Making Good on Vaca'S Promise: Apportioning Back Pay to Achieve Remedial Goals

This article considers the apportionment of damages when two parties are liable, but each is responsible for a different duty to the plaintiff, and each has potentially a different degree of culpability for the injury. Employees may bring a hybrid section 301 action when they have been discharged counter to a collective bargaining agreement and the union fails to resolve the matter to the employee’s satisfaction. In this hybrid action, the employee sues both the employer on the collective bargaining agreement and the union for breach of its duty to represent the employee fairly. In Vaca v. Sipes, the United States Supreme Court held that liability need be apportioned according to the damage caused by the fault of each. Lower courts generally interpreted this language as assigning to unions liability for attorney’s fees and assigning liability to employers for all back pay. However, in Bowen v. United States Postal Service, the Supreme Court held that a union can be liable for some back pay, a significantly greater portion of the damage award. Apportioning chonologically assigns most of the backpay award to unions because of the prolonged length of time from arbitration to the issue being resolved at judgment. The article examines the dimensions of the apportionment problem, critically examines the decision in Bowen, and sets forth a proposal for apportioning damages. This proposed rule for apportioning liability for back pay awards between unions and employers offers significant advantages over the strictly chronological method.
Adding alfalfa to an annual crop rotation shifts the composition and functional responses of tomato rhizosphere microbial communities

Abstract Alfalfa (Medicago sativa L.) is widely cultivated to reduce nitrogen (N) fertilizer inputs for the subsequent crop and can improve soil nitrogen (N) availability and crop yields, widely referred to as the “rotation effect.” The soil mechanisms behind these effects may be due to changes associated with the rhizosphere microbial community of alfalfa. We hypothesized that a compositionally and functionally distinct microbial community would colonize the rhizosphere of tomato plants grown following alfalfa, compared to following maize, and that some of the microbial groups would be carried over from the alfalfa. We also hypothesized that including alfalfa in rotation would lead to greater abundance of genes associated with nitrogen cycling in the tomato rhizosphere. Amplicon sequencing targeting the 16s rDNA gene of bacteria and ITS of fungi were employed to characterize the functional and compositional diversity of the rhizosphere microbial community in two systems under tomato cultivation at the Russell Ranch Sustainable Agriculture Facility Century Experiment (Davis, CA, USA): i) maize-tomato rotation in which we sampled tomatoes (CMT); and ii) alfalfa-maize-tomato rotation in which we sampled tomatoes (AMTT) and alfalfa (AMTA). Bacterial and fungal communities were significantly different among the three systems, with AMTA showing the greatest differences from the others, consistent with the importance of plant species in recruiting specific rhizosphere microbial communities. Changes between the tomato systems were primarily due to increased abundances of bacterial groups Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes and the fungal group Glomeromycota that includes arbuscular mycorrhizal fungi. The abundance of bacterial and fungal genera, Niastella, Kribbella and Preussia was similar in AMTA and AMTT but not in CMT, which suggests a carry-over effect from alfalfa to the subsequent tomato crop rhizosphere. Groups enriched or carried over into tomato included taxa with the ability to enhance soil nutrient availability, plant growth promotion, and suppress harmful effects of pathogens. Genes encoding enzymes related to denitrification were significantly less abundant in the tomato rhizosphere following alfalfa than maize. Improving our understanding of how crop rotation influences soil microbial community composition and functions could enable the designing of crop rotations to foster the proliferation of specific beneficial microbial groups.
Heterotropic Roles of Divalent Cations in the Establishment of Allostery and Affinity Maturation of Integrin αXβ2

SummaryAllosteric activation and silencing of leukointegrins transpire through highly complex structural changes between and within domains, mediating integrin affinity and bidirectional allostery relay. However, the landscape of these conformational changes, which is essential for elaborating integrin dynamics on cell surfaces and designing leukointegrin specific small molecules, has not yet been mapped. Herein we combine biophysical approaches and cell-based affinity assays to fine-tune the conformational dynamism and adhesiveness of a leukocyte integrin, αXβ2, using its physiological cofactor Mg2+. Stepwise addition of Mg2+ revealed two mutually coupled events for the αXβ2 ligand-binding domain—called the αX I-domain—corresponding to allostery establishment and affinity maturation. Electrostatic alterations in the statistically co-evolved Mg2+-binding site establish long-range couplings, leading to pH and Mg2+-occupancy dependent bimodal stability change in the αX I-domain fold. The ligand-binding sensorgrams revealed composite affinity events for the αX I-domain accounting for the multiplicity of conformational states existing in the solution. This bi-faceted transition appears to progressively amalgamate the adhesiveness and allostery within the structural interconversion zone. This work highlights how the intrinsically flexible architecture endows a dynamic continuum to the αI-domain structure on the intact integrin platform, thereby progressively regulating allostery establishment and affinity maturation. This dynamic characteristic appears as a specialization of the αX I-domain and is consistent with its rapid equilibration between open and closed conformations, facilitating rapid upregulation of leukocyte adhesiveness and activation.
Transforming rate capability through self-heating of energy-dense and next-generation batteries

Abstract We demonstrate that an energy-dense, 288 Wh kg−1 lithium-ion battery can provide 152 Wh kg−1 energy and 1056 W kg−1 power at ultralow temperatures such as −40 or −50 °C, contrary to virtually no performance expected under two simultaneous extremes: 4.04 mAh cm−2 cathode loading and −40 °C. Unleashing this huge potential of current battery materials is achieved through a self-heating structure by embedding a micron-thin nickel foil in the electrochemical energy storage cell. The heating process from −40 to 10 °C consumes only 5.1% of battery energy and takes 77 s. Further, based on the chemistry agnostic nature of self-heating, we present a generic chart to transform rate capability of lithium-ion and lithium metal batteries. These illustrative examples point to a new era of battery structure innovation, significantly broadening the performance envelopes of existing and emerging battery materials for electrified transportation.
Synchronized Cell-Cycle Induction of Engrafting Long-Term Repopulating Stem Cells

We have recently defined the window for marrow stem cell homing into nonablated hosts as the first 24 hours posttransplant. Within this homing window, donor cells rapidly cleared from the peripheral blood and lungs and plateaued in the marrow. We have now assessed the cell-cycle status of the engrafting cells capable of contributing to long-term hematopoiesis using administration of hydroxyurea (HU), a chemotherapy agent with S-phase cell-cycle specificity. HU was given at very short periods following a male bone marrow transplant (0, 3, 6, 12, and 15 hours) into female nonablated hosts, and donor cell engraftment was analyzed after 6 weeks. The data show that quickly after transplant (12 hours), greater than half of the engrafting cells capable of contributing long-term to all levels of the hematopoietic hierarchy are in S-phase. Analysis after 6 weeks included whole bone marrow, peripheral blood, primitive cells with high proliferative potential, and mature lineage-restricted marrow cells. These donor cells appear to be naturally synchronized. When HU was administered at any of the other time points, there was little evidence of cell death 6 weeks postengraftment.
Contribution of a conserved arginine near the active site of Escherichia coli D-serine dehydratase to cofactor affinity and catalytic activity.

Abstract We have employed site-directed mutagenesis to investigate the contribution of a conserved arginyl residue to the catalytic activity and cofactor affinity of D-serine dehydratase, a model pyridoxal 5'-phosphate (vitamin B6) enzyme. Replacement of R-120 in the active site peptide of D-serine dehydratase by L decreased the affinity of the enzyme for pyridoxal 5'-phosphate by 20-fold and reduced turnover by 5-8-fold. kappa cat displayed modified substrate alpha-deuterium isotope effects and altered dependence on both temperature and pH. Analysis of the pH rate profiles of DSD and the R-120----L variant indicated that R-120 interacts electrostatically with catalytically essential ionizable groups at the active site of wild type D-serine dehydratase. The decrease in cofactor affinity observed for DSD(R120L) was not accompanied by significant perturbations in the UV, CD, or 31P NMR spectrum of the holoenzyme, suggesting that the contribution of R-120 to pyridoxal phosphate affinity may be indirect or else involve an interaction with a cofactor functional group other than the 5'-phosphoryl moiety. The properties of two other site-directed variants of D-serine dehydratase indicated that the pyridoxal 5'-phosphate:K-118 Schiff base was indifferent to a small change in the shape of the side chain at position 117 (I-117----L), whereas replacement of K-118 by H resulted in undetectable levels of enzyme. A poor ability to bind cofactor may have rendered DSD(K118H) susceptible to intracellular proteolysis.
A Problem for Pericles

Although ancient Greece perhaps affords the earliest examples of comparative law in action, Zaleukos and Lykourgas being said to have traveled widely gathering information about customary and written law in preparation for the drafting of their codes,' modern Anglo-American comparatists, with a few notable exceptions,2 have left the law of ancient Greece to be studied by archaeologists, philosophers and historians. However, even though these students produced excellent studies, work by jurists is needed. Professor Kelsen's studies in international and maritime law illustrate the benefits to be gained by such study. In homage to him, this modest essay-tracing a few ideas generated in a conversation between Pericles and Protagoras-is presented.
NanI Sialidase, CcpA, and CodY Work Together To Regulate Epsilon Toxin Production by Clostridium perfringens Type D Strain CN3718

ABSTRACT Clostridium perfringens type D strains are usually associated with diseases of livestock, and their virulence requires the production of epsilon toxin (ETX). We previously showed (J. Li, S. Sayeed, S. Robertson, J. Chen, and B. A. McClane, PLoS Pathog 7:e1002429, 2011, http://dx.doi.org/10.1371/journal.ppat.1002429) that BMC202, a nanI null mutant of type D strain CN3718, produces less ETX than wild-type CN3718 does. The current study proved that the lower ETX production by strain BMC202 is due to nanI gene disruption, since both genetic and physical (NanI or sialic acid) complementation increased ETX production by BMC202. Furthermore, a sialidase inhibitor that interfered with NanI activity also reduced ETX production by wild-type CN3718. The NanI effect on ETX production was shown to involve reductions in codY and ccpA gene transcription levels in BMC202 versus wild-type CN3718. Similar to CodY, CcpA was found to positively control ETX production. A double codY ccpA null mutant produced even less ETX than a codY or ccpA single null mutant. CcpA bound directly to sequences upstream of the etx or codY start codon, and bioinformatics identified putative CcpA-binding cre sites immediately upstream of both the codY and etx start codons, suggesting possible direct CcpA regulatory effects. A ccpA mutation also decreased codY transcription, suggesting that CcpA effects on ETX production can be both direct and indirect, including effects on codY transcription. Collectively, these results suggest that NanI, CcpA, and CodY work together to regulate ETX production, with NanI-generated sialic acid from the intestines possibly signaling type D strains to upregulate their ETX production and induce disease. IMPORTANCE Clostridium perfringens NanI was previously shown to increase ETX binding to, and cytotoxicity for, MDCK host cells. The current study demonstrates that NanI also regulates ETX production via increased transcription of genes encoding the CodY and CcpA global regulators. Results obtained using single ccpA or codY null mutants and a ccpA codY double null mutant showed that codY and ccpA regulate ETX production independently of one another but that ccpA also affects codY transcription. Electrophoretic mobility shift assays and bioinformatic analyses suggest that both CodY and CcpA may directly regulate etx transcription. Collectively, results of this study suggest that sialic acid generated by NanI from intestinal sources signals ETX-producing C. perfringens strains, via CcpA and CodY, to upregulate ETX production and cause disease.
Identification of drug-resistant subpopulations in canine hemangiosarcoma

Canine hemangiosarcoma is a rapidly progressive disease that is poorly responsive to conventional chemotherapy. Despite numerous attempts to advance treatment options and improve outcomes, drug resistance remains a hurdle to successful therapy. To address this problem, we used recently characterized progenitor cell populations derived from canine hemangiosarcoma cell lines and grown as non-adherent spheres to identify potential drug resistance mechanisms as well as drug-resistant cell populations. Cells from sphere-forming cultures displayed enhanced resistance to chemotherapy drugs, expansion of dye-excluding side populations and altered ATP-binding cassette (ABC) transporter expression. Invasion studies demonstrated variability between cell lines as well as between sphere and monolayer cell populations. Collectively, our results suggest that sphere cell populations contain distinct subpopulations of drug-resistant cells that utilize multiple mechanisms to evade cytotoxic drugs. Our approach represents a new tool for the study of drug resistance in hemangiosarcoma, which could alter approaches for treating this disease.
Chiral sum frequency generation for in situ probing proton exchange in antiparallel β-sheets at interfaces.

Studying hydrogen/deuterium (H/D) exchange in proteins can provide valuable insight on protein structure and dynamics. Several techniques are available for probing H/D exchange in the bulk solution, including NMR, mass spectroscopy, and Fourier transform infrared spectroscopy. However, probing H/D exchange at interfaces is challenging because it requires surface-selective methods. Here, we introduce the combination of in situ chiral sum frequency generation (cSFG) spectroscopy and ab initio simulations of cSFG spectra as a powerful methodology to probe the dynamics of H/D exchange at interfaces. This method is applied to characterize H/D exchange in the antiparallel β-sheet peptide LK7β. We report here for the first time that the rate of D-to-H exchange is about 1 order of magnitude faster than H-to-D exchange in the antiparallel structure at the air/water interface, which is consistent with the existing knowledge that O–H/D dissociation in water is the rate-limiting step, and breaking the O–D bond is slo...
Versatile approach to synthesis of 2-D hexagonal ultra-large-pore periodic mesoporous organosilicas

Periodic mesoporous organosilicas (PMOs) with methylene (–CH2–), ethylene (–CH2CH2–), ethenylene (–CHCH–) and phenylene (–C6H4–) framework groups were synthesized with 2-dimensional hexagonal structures of very large cylindrical mesopores. A combination of a commercially available triblock copolymer Pluronic P123 (EO20PO70EO20) with a judiciously chosen micelle swelling agent (cyclohexane and 1,3,5-triisopropylbenzene) was used as a micellar template, and the initial step of the synthesis was performed at temperature between 10 and 18 °C, followed by a hydrothermal treatment at 100–150 °C. The PMOs were characterized using small-angle X-ray scattering (SAXS), nitrogen adsorption, transmission electron microscopy, and solid-state 29Si NMR. For all PMO compositions, the formation of 2-D hexagonal structures with (100) interplanar spacing, d100, up to 21–26 nm was achieved, which is at least seven nanometres larger than d100 reported earlier for any PMO. The nominal (BJH) pore diameters up to 20–27 nm were achieved for the considered compositions of PMOs with 2-D hexagonal ordering, while even larger pore sizes were sometimes attained for disordered or weakly ordered structures. The mesopores exhibited constrictions or narrow entrances that were widened by increasing the hydrothermal treatment temperature. The pore diameter tended to increase as an initial synthesis temperature decreased, allowing for the pore size adjustment, but the useful temperature range depended on the bridging group. The present work suggests that the low-temperature micelle-templated synthesis with judicious selected swelling agents is a general pathway to ultra-large-pore 2-D hexagonal PMOs with both aliphatic and aromatic bridging groups.
A first course in computational science: (why a math book isn't enough)

There is a change underway in the CS curriculum that reflects a renewed emphasis upon solving applications. Computational science applies solution methods to various scientific models. However, following a computational science approach means more than just using formulas out of a math book. It means having a scientific mindset, understanding and using a scientific approach, thoroughly testing both the theoretical models and the specific implementation of these models, knowing when to use analytic methods instead of numerical ones, using graphics to improve understanding, and knowing how to explain the results of these models to others. This paper addresses what has been learned in designing and teaching a first course in computational science at the undergraduate level.
Acclimation to sublethal exposures to a model nonpolar narcotic : population growth kinetics and membrane lipid alterations in Tetrahymena pyriformis

Abstract Tetrahymena pyriformis has been shown to acclimate (i.e. phenotypic change) to the presence of sublethal levels of hydrophobic organic chemicals considered to act via nonpolar narcosis mode of toxic action. The theoretical site of action for narcosis is the cellular membrane. The objective of this work was to parallel population growth kinetics with molecular toxicology to investigate acclimation. To this end naive and pre-exposed populations of ciliates were exposed to sublethal concentrations of the model nonpolar narcotic, 1-octanol. A control, solvent control, and three sublethal concentrations of 1-octanol were tested. Naive populations exposed to 1-octanol exhibited a concentration dependent lag phase in growth where there was no growth followed by growth at rates similar to control populations. Pre-exposed populations transferred to the same or a lower concentration did not exhibit a lag phase and grew at rates equal to control populations. Pre-exposed populations transferred to a higher concentration exhibited a lag phase in growth. This lag phase was shorter for pre-exposed populations than for naive populations. The relative percent of the following fatty acid methyl esters (FAMEs) did not change with 1-octanol exposure: 12:0, 14:0, 15:0, iso15:0, and 17:0. However, an increase was observed for FAMEs 16:0 and 18:0 with exposure to 1-octanol. Conversely, with exposure there was a decrease for the following FAMEs: 16:1, 18:1, and 18:2Δ6,11. The overall decrease in the number of π-bonds is thought to be related to a net decrease in overall fluidity. Additionally, there was an increase in the ratio of 16/18 carbon FAMEs implicating physical accommodation of the compound within the membrane. Molecular changes are directly correlated with the population growth trends.