bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and optical properties of Mg-Al layered double hydroxides precursor powders
Authors: Lin Chia-Hsuan , Chu Hsueh-Liang , Hwang Weng-Sing , Wang Moo-Chin , Ko Horng-Huey
Published: December 2017

The synthesis and optical properties of Mg-Al layered double hydroxide (LDH) precursor powders were investigated using X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution TEM (HRTEM), UV-transmission spectrometer, and fluorescence spectrophotometer. The FT-IR results show that the intense absorption at around 1363–1377 cm-1 can be assigned to the antisymmetric ν3 mode of interlayer carbonate anions because the LDH phase contains some CO32-. The XRD results show that all of the Mg-Al LDH precursor powders contain only a single phase of [Mg0.833Al0.167(OH)2](CO3)0.083·(H2O)0.75 but have broad and weak intensities of peaks. All of Mg-Al LDHs precursor powders before calcination have the same photoluminescence (PL) spectra. Moreover, these spectra were excited at λex = 235 nm, and the broad emission band was in the range 325-650 nm. In the range, there were relatively strong intensity at around 360, 407 and 510 nm, respectively.
Doping dependence of the contact resistivity of end-bonded metal contacts to thin heavily doped semiconductor nanowires
Authors: Shukkoor Anvar A. , Karmalkar Shreepad
Published: December 2017

We study the resistivity, ρcN, of end-bonded contacts to semiconductor NanoWires (NWs) of radius R = 5–10 nm over doping Nd = 1018–1020 cm−3. The study is important for NW device design and characterization. It reports realistic calculations of ρcN and highlights and explains how ρcN differs significantly from the resistivity ρcB of bulk contacts. First, the space-charge width in NW contacts is increased by the surrounding field which depends on R, contact geometry, and ambient dielectric; this width also depends on surface charge and dielectric confinement which reduces dopant ionization. Second, thin NWs have a low effective lifetime, τN, due to surface recombination. Third, NW contacts have a lesser image force barrier lowering due to the higher space-charge width. Due to these factors, apart from tunneling (which decides ρcB), space-charge region generation-recombination current also affects ρcN. As Nd is raised from 1018 to 1020 cm−3, ρcB falls rapidly, but ρcN varies slowly and may even increase up to 3–5 × 1018 and then falls rapidly. Further, ρcN/ρcB can be ≪1 at Nd = 1 × 1018 cm−3, reaches a peak ≫1 around Nd = 1 × 1019 cm−3, and → 1 at Nd = 1 × 1020 cm−3, e.g., for 0.8 V contact barrier on 10 nm thick n-type silicon NWs with τN = 1 ps embedded in SiO2, at T = 300 K, even a 10 nm contact extension yields a peak of 75 at Nd = 8 × 1018 cm−3. We study changes in ρcN/ρcB versus Nd behavior with R, contact geometry, ambient dielectric, surface charge, τN, T, tunneling mass, and barrier height.
Spin-orbit torque based magnetization switching in Pt/Cu/[Co/Ni]5 multilayer structures
Authors: Ostwal Vaibhav , Penumatcha Ashish , Hung Yu-Ming , Kent Andrew D. , Appenzeller Joerg
Published: December 2017

Spin-Orbit Torque (SOT) in Heavy Metal/Ferromagnet (HM/FM) structures provides an important tool to control the magnetization of FMs and has been an area of interest for memory and logic implementation. Spin transfer torque on the FM in such structures is attributed to two sources: (1) the Spin Hall effect in the HM and (2) the Rashba-effect at the HM/FM interface. In this work, we study the SOT in a Pt/[Co,Ni] structure and compare its strength with the SOT in a Pt/Cu/[Co,Ni] structure where copper, a metal with a low spin-orbit interaction, is inserted between the Pt (HM) layer and the [Co,Ni] (FM) layer. We use an AC harmonic measurement technique to measure the strength of the SOT on the magnetic thin-film layer. Our measurements show that a significant SOT is exerted on the magnetization even after a 6 nm thick copper layer is inserted between the HM and the FM. Also, we find that this torque can be used to switch a patterned magnetic layer in the presence of an external magnetic field.
In-situ transport and microstructural evolution in GaN Schottky diodes and epilayers exposed to swift heavy ion irradiation
Authors: Kumar Ashish , Singh R. , Kumar Parmod , Singh Udai B. , Asokan K. , Karaseov Platon A. , Titov Andrei I. , Kanjilal D.
Published: December 2017

A systematic investigation of radiation hardness of Schottky barrier diodes and GaN epitaxial layers is carried out by employing in-situ electrical resistivity and cross sectional transmission electron microscopy (XTEM) microstructure measurements. The change in the current transport mechanism of Au/n-GaN Schottky barrier diodes due to irradiation is reported. The role of irradiation temperature and ion type was also investigated. Creation of damage is studied in low and medium electron energy loss regimes by selecting different ions, Ag (200 MeV) and O (100 MeV) at various fluences at two irradiation temperatures (80 K and 300 K). GaN resistivity increases up to 6 orders of magnitude under heavy Ag ions. Light O ion irradiation has a much lower influence on sheet resistance. The presence of isolated defect clusters in irradiated GaN epilayers is evident in XTEM investigation which is explained on the basis of the thermal spike model.
High energy proton induced radiation damage of rare earth permanent magnet quadrupoles
Authors: Schanz M. , Endres M. , Löwe K. , Lienig T. , Deppert O. , Lang P. M. , Varentsov D. , Hoffmann D. H. H. , Gutfleisch O.
Published: December 2017

Permanent magnet quadrupoles (PMQs) are an alternative to common electromagnetic quadrupoles especially for fixed rigidity beam transport scenarios at particle accelerators. Using those magnets for experimental setups can result in certain scenarios, in which a PMQ itself may be exposed to a large amount of primary and secondary particles with a broad energy spectrum, interacting with the magnetic material and affecting its magnetic properties. One specific scenario is proton microscopy, where a proton beam traverses an object and a collimator in which a part of the beam is scattered and deflected into PMQs used as part of a diagnostic system. During the commissioning of the PRIOR (Proton Microscope for Facility for Antiproton and Ion Research) high energy proton microscope facility prototype at Gesellschaft für Schwerionenforschung in 2014, a significant reduction of the image quality was observed which was partially attributed to the demagnetization of the used PMQ lenses and the corresponding decrease of the field quality. In order to study this phenomenon, Monte Carlo simulations were carried out and spare units manufactured from the same magnetic material—single wedges and a fully assembled PMQ module—were deliberately irradiated by a 3.6 GeV intense proton beam. The performed investigations have shown that in proton radiography applications the above described scattering may result in a high irradiation dose in the PMQ magnets. This did not only decrease the overall magnetic strength of the PMQs but also caused a significant degradation of the field quality of an assembled PMQ module by increasing the parasitic multipole field harmonics which effectively makes PMQs impractical for proton radiography applications or similar scenarios.
Tunable multiple emissions in manganese-concentrated sulfide through simultaneous tailoring of Mn-site coordination and Mn-Mn pair geometry
Authors: Chen Zitao , Song Enhai , Ye Shi , Zhang Qinyuan
Published: December 2017

In contrast to generally single-band visible emission feature from Mn2+, simultaneous visible (VIS) and near-infrared (NIR) multiple emissions are demonstrated in Mn2+ concentrated sulfide (MnS) by only involving a single crystallographic site. Upon varying the Mn2+-site coordination and/or Mn-Mn pairs geometry in different structural MnS, the multiple emissions from divalent manganese can be easily tuned from 575 to 720 nm (VIS) or from 880 to 900 or 1380 nm (NIR), respectively. The excitation spectroscopy and the luminescent decay, together with crystal structural analyses, are employed to investigate the electronic transition and the excited state dynamics of these Mn2+ concentrated systems. It is found that the VIS and NIR emissions can be ascribed to the isolated Mn2+ ion and exchange coupled Mn-Mn pair center, respectively. The effect of crystal field and bridging geometry, as well as temperature on the exchange coupled Mn2+ pairs NIR emissive center, is also investigated in detail. This work not only provides keen insights into the de-excitation pathway of Mn2+-concentrated material, but also offers the possibilities of designing a novel NIR emitting source for various photonic applications.
Near band edge photoluminescence of ZnO nanowires: Optimization via surface engineering
Authors: Yan Danhua , Zhang Wenrui , Cen Jiajie , Stavitski Eli , Sadowski Jerzy T. , Vescovo Elio , Walter Andrew , Attenkofer Klaus , Stacchiola Darío J. , Liu Mingzhao
Published: December 2017

Zinc oxide (ZnO) nanowire arrays have potential applications for various devices such as ultra-violet light emitting diodes and lasers, where photoluminescence of intense near band edge emission without defect emissions is usually desired. Here, we demonstrate, counter-intuitively, that the near band edge emission may become dominant by introducing certain surface defects to ZnO nanowires via surface engineering. Specifically, near band edge emission (NBE) is effectively enhanced after a low pressure O2 plasma treatment that sputters off surface oxygen species to produce a reduced and oxygen vacancy-rich surface. The effect is attributed to the lowered surface valence band maximum of the reduced ZnO surface that creates an accumulative band bending, which screens the photo-generated minority carriers (holes) from reaching or being trapped by the surface defects.
Frequency-dependent hydrodynamic interaction between two solid spheres
Authors: Jung Gerhard , Schmid Friederike
Published: December 2017

Hydrodynamic interactions play an important role in many areas of soft matter science. In simulations with implicit solvent, various techniques such as Brownian or Stokesian dynamics explicitly include hydrodynamic interactions a posteriori by using hydrodynamic diffusion tensors derived from the Stokes equation. However, this equation assumes the interaction to be instantaneous which is an idealized approximation and only valid on long time scales. In the present paper, we go one step further and analyze the time-dependence of hydrodynamic interactions between finite-sized particles in a compressible fluid on the basis of the linearized Navier-Stokes equation. The theoretical results show that at high frequencies, the compressibility of the fluid has a significant impact on the frequency-dependent pair interactions. The predictions of hydrodynamic theory are compared to molecular dynamics simulations of two nanocolloids in a Lennard-Jones fluid. For this system, we reconstruct memory functions by extending the inverse Volterra technique. The simulation data agree very well with the theory, therefore, the theory can be used to implement dynamically consistent hydrodynamic interactions in the increasingly popular field of non-Markovian modeling.
Enhanced supercapacitance of activated vertical graphene nanosheets in hybrid electrolyte
Authors: Ghosh Subrata , Sahoo Gopinath , Polaki S. R. , Krishna Nanda Gopala , Kamruddin M. , Mathews Tom
Published: December 2017

Supercapacitors are becoming the workhorse for emerging energy storage applications due to their higher power density and superior cycle life compared to conventional batteries. The performance of supercapacitors depends on the electrode material, type of electrolyte, and interaction between them. Owing to the beneficial interconnected porous structure with multiple conducting channels, vertical graphene nanosheets (VGN) have proved to be leading supercapacitor electrode materials. Herein, we demonstrate a novel approach based on the combination of surface activation and a new organo-aqueous hybrid electrolyte, tetraethylammonium tetrafluoroborate in H2SO4, to achieve significant enhancement in supercapacitor performance of VGN. As-synthesized VGN exhibits an excellent supercapacitance of 0.64 mF/cm2 in H2SO4. However, identification of a novel electrolyte for performance enhancement is the subject of current research. The present manuscript demonstrates the potential of the hybrid electrolyte in enhancing the areal capacitance (1.99 mF/cm2) with excellent retention (only 5.4% loss after 5000 cycles) and Coulombic efficiency (93.1%). In addition, a five-fold enhancement in the capacitance of VGNs (0.64 to 3.31 mF/cm2) with a reduced internal resistance is achieved by the combination of KOH activation and the hybrid electrolyte.
Conduction band fluctuation scattering due to alloy clustering in barrier layers in InAlN/GaN heterostructures
Authors: Li Qun , Chen Qian , Chong Jing
Published: December 2017

In InAlN/GaN heterostructures, alloy clustering-induced InAlN conduction band fluctuations interact with electrons penetrating into the barrier layers and thus affect the electron transport. Based on the statistical description of InAlN compositional distribution, a theoretical model of the conduction band fluctuation scattering (CBFS) is presented. The model calculations show that the CBFS-limited mobility decreases with increasing two-dimensional electron gas sheet density and is inversely proportional to the squared standard deviation of In distribution. The AlN interfacial layer can effectively suppress the CBFS via decreasing the penetration probability. This model is directed towards understanding the transport properties in heterostructure materials with columnar clusters.
Plasmonic and metallic optical properties of Au/SiO2 metal-insulator films
Authors: Battie Yann , En Naciri Aotmane , Vergnat Michel
Published: December 2017

In this paper, the optical properties and the growth mechanism of Au/SiO2 metal-insulator films (MIFs) are investigated by combining ellipsometry and transmission electron microscopy. The ellipsometric measurements, analyzed by using effective medium theories, show that the growth mechanism involves a Volmer-Weber growth mode while the morphology and the optical properties of Au/SiO2 MIFs are directly related to the percolation of the Au nanostructures. Indeed, below the percolation threshold of Au, the MIFs consist of ellipsoidal Au inclusions embedded in a SiO2 matrix. These insulating films present anisotropic plasmonic properties, attributed to the asymmetric interactions between nanaoparticles (NPs), which can be modeled according to the interacted shape distributed nanoparticle effective medium theory. At the percolation threshold of Au, an insulator-to-metal transition is observed. The MIFs simultaneously exhibit plasmonic and metallic optical properties, which can be described by the Bruggeman theory. The density of free electrons increases and the MIFs become more and more conductive as the Au volume fraction increases. We also demonstrate that for a high Au volume fraction, Bruggeman and Maxwell Garnett theories converge toward the same results, suggesting that the film is composed of isolated SiO2 inclusion embedded in a gold matrix.
Effects of collector plasma in the relativistic backward wave oscillator
Authors: Miao Tianze , Bai Xianchen , Sun Jun , Zhang Xiaowei , Cao Yibing , Wu Ping , Shi Yanchao , Shao Hao
Published: December 2017

The effects of a collector plasma in a relativistic backward wave oscillator are investigated using a numerical simulation. Analyzing mainly the diffusion process, the results show a fast plasma diffusion occurring as one of the most important reasons for pulse shortening. In this process, the fast plasma affects the modulation of the intense relativistic electron beams, leads to drifting of the microwave frequency, absorbs gigawatts of microwave power, and finally causes pulse shortening. Here, the mechanism underpinning fast diffusion is mainly attributed to the standing wave pattern of the microwave field in the interaction region and the space charge effect. This paper reveals the change in the system after pulse shortening caused by fast diffusion and suggests a measure to control this process by restraining the collector plasma.
Tuning the metamagnetism in a metallic helical antiferromagnet
Authors: Ma S. C. , Liu K. , Ma C. C. , Ge Q. , Zhang J. T. , Hu Y. F. , Liu E. K. , Zhong Z. C.
Published: December 2017

The antiferromagnetic (AFM)-ferromagnetic (FM) conversion in martensite was observed in Mn/Ni-substitution upon FM elements, such as Fe or Co, in MnNiGe helical antiferromagnets. Here, we report an AFM-FM conversion and consequently a sharp magnetic-field-driven metamagnetic martensitic transformation from paramagnetic (PM) austenite to FM martensite in the Ni- and Mn-substituted MnNiGe alloys with indium, a non-magnetic and large-sized main group element. Accordingly, a giant magnetocaloric effect such that a twofold increase of the magnetic entropy change in MnNi0.92GeIn0.08 and even a nearly threefold increase in the Mn0.92NiGeIn0.08 alloy is obtained with respect to the MnNiGe0.95In0.05 alloy. The origin of AFM-FM conversion and resultantly sharp magnetic-field-induced PM-FM metamagnetic transformation is discussed based on the first-principles calculations and X-ray absorption spectroscopic results.
Metal organic framework Cu9Cl2(cpa)6 as tunable molecular magnet
Authors: Hamilton Heather S. C. , Farmer William M. , Skinner Samuel F. , ter Haar Leonard W.
Published: December 2017

Chemical modifications of the magnetic metal organic framework (MOF) Cu9X2(cpa)6·42H2O (X = F, Cl, Br; cpa = anion of 2-carboxypentonicacid) have been investigated as a means of modifying, in a tunable manner, the magnetism of this 2-D material best described as a triangles-in-triangles (TIT) or triangulated-Kagomé-latttice (TKL). Since numerous theoretical studies have already attempted to describe the enigmatic ground state of this Heisenberg lattice, tunable chemical modifications should provide an excellent opportunity to expand this class of materials for studies concerning fundamental physics of frustrated spins, and applications such as adiabatic demagnetization refrigeration (ADR) that depend on the magnetocaloric effect (MCE). The chemical modification investigated is the intercalation of d- and f-orbital ions into the voids of the framework (channels of nearly 20 Å diameter). Magnetic measurements in the temperature range 1.8 – 300 K confirm signature features of TKL magnetism in intercalated samples persist, specifically: i) large negative Weiss constant (θCW); ii) absence of a phase transition down to 1.8 K; iii) minimum in χMT; iv) low temperature χMT values increasingly divergent at low fields indicating net ferromagnetic correlations; and, v) increasing field dependence of magnetization at low temperatures suggestive of intermediate plateaus, or ferrimagnetism, not saturation.
On the discrimination between nucleation and propagation in nanomagnetic logic devices
Authors: Ziemys Grazvydas , Csaba Gyorgy , Becherer Markus
Published: December 2017

In this paper we present the extensive nucleation and propagation characterization of fabricated nanomagnets by applying ns-range magnetic field pulses. For that, an artificial nucleation center (ANC) is created by focused ion beam irradiation (FIB) of a 50 x 50 nm area at the side of a Co/Pt island as typically used in Nanomagnetic Logic with perpendicular anisotropy (pNML). Laser-Kerr Microscope is applied for statistical evaluation of the switching probability of the whole magnet, while the wide-field-Kerr microscopy is employed to discriminate between the nucleation process (which takes place at the irradiated ANC area) and the domain wall propagation process along the magnet. We show that the nanomagnet can be treated as a single Stoner-Wolfhart particle above 100 ns field-pulse width, as the whole magnetization is switched during the field-pulse. By contrary, for field-pulse width below 100 ns, the domain wall (DW) motion is the limiting process hindering full magnetization reversal on that time-scale. However, the nucleation still follows the Arrhenius law. The results allow precise understanding of the reversal process and highlight the need for faster DW speed in pNML materials.
Self-trapped holes in β-Ga2O3 crystals
Authors: Kananen B. E. , Giles N. C. , Halliburton L. E. , Foundos G. K. , Chang K. B. , Stevens K. T.
Published: December 2017

We have experimentally observed self-trapped holes (STHs) in a β-Ga2O3 crystal using electron paramagnetic resonance (EPR). These STHs are an intrinsic defect in this wide-band-gap semiconductor and may serve as a significant deterrent to producing usable p-type material. In our study, an as-grown undoped n-type β-Ga2O3 crystal was initially irradiated near room temperature with high-energy neutrons. This produced gallium vacancies (acceptors) and lowered the Fermi level. The STHs (i.e., small polarons) were then formed during a subsequent irradiation at 77 K with x rays. Warming the crystal above 90 K destroyed the STHs. This low thermal stability is a strong indicator that the STH is the correct assignment for these new defects. The S = 1/2 EPR spectrum from the STHs is easily observed near 30 K. A holelike angular dependence of the g matrix (the principal values are 2.0026, 2.0072, and 2.0461) suggests that the defect's unpaired spin is localized on one oxygen ion in a nonbonding p orbital aligned near the a direction in the crystal. The EPR spectrum also has resolved hyperfine structure due to equal and nearly isotropic interactions with 69,71Ga nuclei at two neighboring Ga sites. With the magnetic field along the a direction, the hyperfine parameters are 0.92 mT for the 69Ga nuclei and 1.16 mT for the 71Ga nuclei.
Excitations of interface pinned domain walls in constrained geometries
Authors: Martins S. M. S. B. , Oliveira L. L. , Rebouças G. O. G. , Dantas Ana L. , Carriço A. S.
Published: December 2017

We report a theoretical investigation of the equilibrium pattern and the spectra of head-to-head and Neel domain walls of flat Fe and Py stripes, exchange coupled with a vicinal antiferromagnetic substrate. We show that the domain wall excitation spectrum is tunable by the strength of the interface field. Furthermore, strong interface coupling favors localized wall excitations.
Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator
Authors: Shen Yi , Liu Yi , Ye Mao , Zhang Huang , Wang Wei , Xia Liansheng , Wang Zhiwen , Yang Chao , Shi Jinshui , Zhang Linwen , Deng Jianjun
Published: December 2017

A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.
Reef fish at a remote tropical island (Principe Island, Gulf of Guinea): disentangling taxonomic, functional and phylogenetic diversity patterns with depth
Authors: Tuya F. , Herrero-Barrencua A. , Bosch N. E. , Abreu A. D. , Haroun R.
Published: December 2017

The ecology of reef fish varies with depth, although patterns in diversity remain largely undescribed, in particular the complementarity of their taxonomic, functional and phylogenetic facets. In the present study we investigated patterns of taxonomic, functional and phylogenetic diversity of fish on 21 reefs, at depths ranging from 3 to 31m, at Príncipe Island (Gulf of Guinea). Taxonomic and functional diversity decreased monotonically with depth; the pattern was less accentuated for phylogenetic diversity. Functional diversity was saturated at high levels of taxonomic diversity, reflecting redundancy in species traits, particularly at the shallower reefs. Functional diversity increased linearly with phylogenetic diversity; thus, increasing niche availability seems to translate into a larger diversity of phylogenies. Dissimilarities in the structure and composition of fish assemblages among reefs were correlated with differences in depth, including a progressive turnover in species. Depth affected the functional traits of nearshore reef fish. Trophic breadth decreased with depth; carnivores and planktivores increased with depth, whereas herbivores decreased with depth. Small-sized fusiform fish dominated on the shallowest reefs. In summary, the present study demonstrated decays in biodiversity, from different perspectives, of reef fish with depth, which are connected with shifts in fish traits.
SbcC-SbcD and ExoI process convergent forks to complete chromosome replication
Authors: Wendel Brian M. , Cole Jessica M. , Courcelle Charmain T. , Courcelle Justin
Published: December 2017

Significance

SbcC-SbcD and ExoI belong to a class of highly conserved nucleases that are critical to genome stability, but whose cellular function remains poorly understood. Human homologs of these proteins are essential for viability and normal development, and lead to severe developmental abnormalities and cancer predisposition when mutated. Here we show that these enzymes process DNA intermediates at sites where replication forks converge and are required for chromosome replication to complete normally. Cells lacking these gene products are unable to complete replication normally, and rely on an aberrant recombinational mechanism to maintain viability that leads to genomic instability and amplifications at these sites, similar to that seen in human cancers where these genes have been found to be inactivated.
Spatial decay in transient heat conduction for general elongated regions
Authors: Knops R. , Quintanilla R.
Published: December 2017

Zanaboni’s procedure for establishing Saint-Venant’s principle is extended to anisotropic homogeneous transient heat conduction on regions that are successively embedded in each other to become indefinitely elongated. No further geometrical restrictions are imposed. The boundary of each region is maintained at zero temperature apart from the common surface of intersection which is heated to the same temperature assumed to be of bounded time variation. Heat sources are absent. Subject to these conditions, the thermal energy, supposed bounded in each region, becomes vanishingly small in those parts of the regions sufficiently remote from the heated common surface. As with the original treatment, the proof involves certain monotone bounded sequences, and does not depend upon differential inequalities or the maximum principle. A definition of an elongated region is presented.
Effects of Cyclophosphamide and/or Doxorubicin in a Murine Model of Postchemotherapy Cognitive Impairment
Authors: Flanigan Timothy J , Anderson Julie E , Elayan Ikram , Allen Antiño R , Ferguson Sherry A
Published: December 2017

Postchemotherapy cognitive impairment, or PCCI, is a common complaint, particularly among breast cancer patients. However, the exact nature of PCCI appears complex. To model the human condition, ovariectomized C57BL/6J mice were treated intravenous weekly for 4 weeks with saline, 2 mg/kg doxorubicin (DOX), 50 mg/kg cyclophosphamide (CYP), or DOX + CYP. For the subsequent 10 weeks, mice were assessed on several behavioral tests, including those measuring spatial learning and memory. After sacrifice, hippocampal spine density and morphology in the dentate gyrus, CA1, and CA3 regions were measured. Additionally, hippocampal levels of total glutathione, glutathione disulfide, MnSOD, CuZnSOD, and cytokines were measured. Body weight decreased in all groups during treatment, but recovered post-treatment. Most behaviors were unaffected by drug treatment: Open field activity, motor coordination, grip strength, water maze and Barnes maze performance, buried food test performance, and novel object and object location recognition tests. There were some significant effects of CYP and DOX + CYP treatment during the initial test of home cage behavior, but these did not persist into the second and third test times. Density of stubby spines, but not mushroom or thin spines, in the dentate gyrus was significantly decreased in the DOX, CYP, and DOX + CYP treatment groups. There were no significant effects in the CA1 or CA3 regions. CuZnSOD levels were significantly increased in DOX + CYP-treated mice; other hippocampal antioxidant levels were unaffected. Most cytokines showed no treatment-related effects, but IL-1β, IL-6, and IL-12 were slightly reduced in mice treated with DOX + CYP. Although the animal model, route of exposure, and DOX and CYP doses used here were reflective of human exposure, there were only sporadic effects due to chemotherapeutic treatment.
Fungicide Resistance in Botrytis fragariae and Species Prevalence in the Mid-Atlantic United States
Authors: Dowling Madeline E. , Hu Meng-Jun , Schnabel Guido
Published: December 2017

Botrytis fragariae was recently described causing gray mold of strawberry in Germany and the United States. The goal of the present study was to determine its prevalence, distribution, and sensitivity to fungicides in strawberry fields of five states. In total, 188 Botrytis isolates were obtained from flowers and fruit collected from the states of Maryland (n = 35), Virginia (n = 38), North Carolina (n = 46), South Carolina (n = 41), and Georgia (n = 28). Only 13 of these were fruit samples and came from South Carolina (n = 5) and Georgia (n = 8). B. fragariae made up 35.1% of the entire collection, and composed close to half of the Botrytis population in North Carolina (43.4%), South Carolina (61.0%), and Georgia (42.9%). One isolate of B. mali was also found, and the rest of the isolates were B. cinerea (sensu lato). B. fragariae and B. cinerea were found coexisting in 11 fields, while other field samples consisted of only B. fragariae (n = 3) or only B. cinerea (n = 10) isolates. B. fragariae isolates with resistance to one or more fungicides were found, and resistance profiles differed from those of B. cinerea, in that no resistance to cyprodinil (FRAC 8) or boscalid and other FRAC 7 botryticides was detected. We detected B. fragariae resistance to the active ingredients thiophanate-methyl, iprodione, fludioxonil, and fenhexamid. We also detected B. fragariae isolates with resistance to up to four chemical classes of fungicides, though most isolates were resistant to one or two chemical classes. In conclusion, isolates of the newly detected species B. fragariae were commonly found on strawberry flowers in the Mid-Atlantic United States, and have developed resistance to many of the most commonly used botryticides. Though the relevance of this species to pre- and postharvest fruit infections is unknown, fludioxonil applications may give this species a competitive advantage over B. cinerea. Controlling this fungus with FRAC 7 fungicides may be an effective way of limiting its spread in strawberry fields.
Engaging Nursing Students: Integrating Evidence-Based Inquiry, Informatics, and Clinical Practice
Authors: Keiffer Melanie R.
Published: December 2017

The nursing research class requires faculty to create a spirit of inquiry while integrating technology, flexibility, and responsiveness to student needs. This article discusses new pedagogies to actively engage students in the evidence-based nursing process and the achievement of course learning outcomes. Through course exemplar, the author demonstrates a creative method to engage traditional baccalaureate nursing students in a nursing project that links evidence to improved patient outcomes.
Developing Resident-Sensitive Quality Measures: A Model From Pediatric Emergency Medicine
Authors: Schumacher Daniel J. , Holmboe Eric S. , van der Vleuten Cees , Busari Jamiu O. , Carraccio Carol
Published: December 2017

Purpose

To begin closing the gap with respect to quality measures available for use among residents, the authors sought to identify and develop resident-sensitive quality measures (RSQMs) for use in the pediatric emergency department (PED) setting.

Method

In May 2016, the authors reviewed National Quality Measures Clearinghouse (NQMC) measures to identify resident-sensitive measures. To create additional measures focused on common, acute illnesses (acute asthma exacerbation, bronchiolitis, closed head injury [CHI]) in the PED, the authors used a nominal group technique (NGT) and Delphi process from September to December 2016. To achieve a local focus for developing these measures, all NGT and Delphi participants were from Cincinnati Children’s Hospital Medical Center. Delphi participants rated measures developed through the NGT in two areas: importance of measure to quality care and likelihood that measure represents the work of a resident.

Results

The review of NQMC measures identified 28 of 183 as being potentially resident sensitive. The NGT produced 67 measures for asthma, 46 for bronchiolitis, and 48 for CHI. These were used in the first round of the Delphi process. After two rounds, 18 measures for asthma, 21 for bronchiolitis, and 21 for CHI met automatic inclusion criteria. In round three, participants categorized the potential final measures by their top 10 and next 5.

Conclusions

This study describes a template for identifying and developing RSQMs that may promote high-quality care delivery during and following training. Next steps should include implementing and seeking validity evidence for the locally developed measures.
What are the dominant cytokines in early rheumatoid arthritis?
Authors: Ridgley Laura A. , Anderson Amy E. , Pratt Arthur G.
Published: December 2017

Purpose of review

Rheumatoid arthritis is a systemic disease of evolving immune dysregulation that culminates in joint destruction and disability. The principle by which pro-inflammatory cytokines may be therapeutically targeted to abrogate disease is well established, but has yet to translate into reliable cures for patients. Emerging insights into cytokine-mediated pathobiology during rheumatoid arthritis development are reviewed, and their implications for future treatment strategies considered.

Recent findings

Accumulating data highlight cytokine perturbations before the clinical onset of rheumatoid arthritis. Some of these have now been linked to the arthritogenic activation of autoantibodies and associated pain and bone destruction in affected joints. These observations suggest cytokines may trigger the transition from systemic immunity to arthritis. Cytokine exposure could furthermore ‘prime’ synovial stromal cells to perpetuate a dominant pro-inflammatory environment. By facilitating cross-talk between infiltrating immune cells and even sustaining ectopic lymphoid structure development in some cases, cytokine interplay ultimately underpins the failure of arthritis to resolve.

Successful therapeutic stratification will depend upon an increasingly sophisticated appreciation of how dominant players amongst cytokine networks vary across time and anatomical space during incipient rheumatoid arthritis. The prize of sustained remission for all patients justifies the considerable effort required to achieve this understanding.
Caregiver Perceptions and Health-Related Quality-of-Life Changes in Cerebral Palsy Patients After Spinal Arthrodesis
Authors: Jain Amit , Sullivan Brian T. , Shah Suken A. , Samdani Amer F. , Yaszay Burt , Marks Michelle C. , Sponseller Paul D.
Published: December 2017

Study Design.

A retrospective analysis of a prospective registry.

Objective.

Our objective was to prospectively assess caregivers’ perceptions regarding changes in the health-related quality of life (HRQL) of patients with cerebral palsy (CP) after spinal arthrodesis. We assessed caregiver perceptions from three perspectives: 1) qualitative assessment of changes in global quality of life, comfort, and health; 2) relative valuation of spine surgery versus other common interventions in CP patients; and 3) quantitative changes in HRQL scores.

Summary of Background Data.

Studies of children with CP who undergo surgical treatment of spinal deformity have focused largely on radiographic changes.

Methods.

We queried a multicenter prospective registry of CP patients with level IV or V motor function according to the Gross Motor Function Classification System who were treated with spinal arthrodesis, and whose caregivers completed preoperative and 2-year postoperative qualitative and quantitative HRQL surveys. A total of 212 caregivers and their patients were included in the study.

Results.

At 2-year follow-up, most caregivers reported that patients’ global quality of life, comfort, and health were “a lot better” after spinal arthrodesis. Spinal arthrodesis was ranked as the most beneficial intervention in the patients’ lives by 74% of caregivers, ahead of hip, knee, and foot surgeries and baclofen pump insertion. Gastrostomy tube insertion was the only intervention ranked superior to spinal arthrodesis in terms of impact. Quantitative HRQL scores improved significantly during 2-year follow-up across various domains.

Conclusion.

In qualitative and quantitative HRQL assessments, caregivers reported overall improvement in patients’ lives after spinal arthrodesis. Caregivers ranked spine surgery as the most beneficial intervention in the patients’ lives, secondary only to gastrostomy tube insertion.

Level of Evidence: 2
Predictive Modeling for Blood Transfusion After Adult Spinal Deformity Surgery
Authors: Durand Wesley M. , DePasse John Mason , Daniels Alan H.
Published: December 2017

Study Design.

Retrospective cohort study.

Objective.

Blood transfusion is frequently necessary after adult spinal deformity (ASD) surgery. We sought to develop predictive models for blood transfusion after ASD surgery, utilizing both classification tree and random forest machine-learning approaches.

Summary of Background Data.

Past models for transfusion risk among spine surgery patients are disadvantaged through use of single-institutional data, potentially limiting generalizability.

Methods.

This investigation was conducted utilizing the American College of Surgeons National Surgical Quality Improvement Program dataset years 2012 to 2015. Patients undergoing surgery for ASD were identified using primary-listed current procedural terminology codes. In total, 1029 patients were analyzed. The primary outcome measure was intra-/postoperative blood transfusion. Patients were divided into training (n = 824) and validation (n = 205) datasets. Single classification tree and random forest models were developed. Both models were tested on the validation dataset using area under the receiver operating characteristic curve (AUC), which was compared between models.

Results.

Overall, 46.5% (n = 479) of patients received a transfusion intraoperatively or within 72 hours postoperatively. The final classification tree model used operative duration, hematocrit, and weight, exhibiting AUC = 0.79 (95% confidence interval 0.73–0.85) on the validation set. The most influential variables in the random forest model were operative duration, surgical invasiveness, hematocrit, weight, and age. The random forest model exhibited AUC = 0.85 (95% confidence interval 0.80–0.90). The difference between the classification tree and random forest AUCs was nonsignificant at the validation cohort size of 205 patients (P = 0.1551).

Conclusion.

This investigation produced tree-based machine-learning models of blood transfusion risk after ASD surgery. The random forest model offered very good predictive capability as measured by AUC. Our single classification tree model offered superior ease of implementation, but a lower AUC as compared to the random forest approach, although this difference was not statistically significant at the size of our validation cohort. Clinicians may choose to implement either of these models to predict blood transfusion among their patients. Furthermore, policy makers may use these models on a population-based level to assess predicted transfusion rates after ASD surgery.

Level of Evidence: 3
Minimum Detectable Measurement Difference for Health-Related Quality of Life Measures Varies With Age and Disability in Adult Spinal Deformity
Authors: Kelly Michael P. , Kim Han Jo , Ames Christopher P. , Burton Douglas C. , Carreon Leah Yacat , Polly David W. , Hostin Richard , Jain Amit , Gum Jeffrey L. , Lafage Virginie , Schwab Frank J. , Shaffrey Christopher I. , Smith Justin S. , Bess Shay
Published: December 2017

Study Design.

Retrospective cohort.

Objective.

To investigate the minimum detectable measurement difference (MDMD) in the Scoliosis Research Society-22r (SRS-22r) outcomes instrument in adult spinal deformity (ASD) and to evaluate the effect of baseline data on measurable difference.

Summary of Background Data.

The minimum clinically important difference (MCID) is the smallest, clinically relevant change observed and has been proposed for the SRS-22r instrument in ASD as 0.4. The MCID must be greater than the MDMD to be useful. The MDMD for the SRS-22r has not been calculated, nor have the effect of patient baseline values on MDMD.

Methods.

A prospective observation cohort was queried for patients treated both operatively and nonoperatively for ASD. Patients with baseline and 1-year, 2-year follow-up SRS-22r data were included in the analysis. The MDMD was calculated using classical test theory and item-response theory methods. Effect size and standardized response means were calculated. The effect of baseline data values was evaluated for MDMD.

Results.

A total 839 Patients were eligible for cohort inclusion with 428 (51%) eligible for analysis with complete data. MDMD for Pain (0.6) and Self-Image (0.5) were greater than 0.4. MDMD varied with age (highest for the youngest patients) and with disability (highest for SF-36 Physical Component Summary <28.6). MDMD was less than 0.4 for Activity (0.3), Mental Health (0.3), and Total Score (0.2). Gender and mental health did not affect MDMD for the SRS-22r instrument.

Conclusion.

An MCID of 0.4 for the SRS-22r total score and domain scores may not be an appropriate value as the calculated MDMD is greater than 0.4 for both the Pain and Self-Image subscores. The MDMD for the SRS-22r instrument varied with age and baseline disability, making the assessment of clinically significant change more difficult using this tool. The MCID must be considered in the setting of the MDMD for instruments used to assess outcomes in ASD.

Level of Evidence: 3
Is Health-related Quality of Life Decreased in Adolescents With Back Pain?
Authors: Gonçalves Tatiana Rehder , Mediano Mauro Felippe Felix , Sichieri Rosely , Cunha Diana Barbosa
Published: December 2017

Study Design.

Cross-sectional study.

Objective.

To evaluate the association between back pain and health-related quality of life (HRQoL) among adolescents.

Summary of Background Data.

The prevalence of back pain has been increasing not only in the adult population but also among children and adolescents. The better knowledge about the association between back pain and health-related quality of life could facilitate the implementation of new intervention strategies on prevention and treatment of back pain.

Methods.

A sample of 350 students from the fifth to ninth grades of one public school in Niterói, Rio de Janeiro, Brazil. Anthropometric measures and information regarding sociodemographic, lifestyle, frequency and intensity of neck (NP), thoracic (TP), and low back pain in the previous month were collected using a personal digital assistant. HRQoL was assessed by KIDSCREEN-27. Multiple linear regression analyses were performed to investigate the association between back pain and HRQoL by sex.

Results.

The mean age of participants was 12.7 (±1.6) years. Frequency of NP, TP, and low back pain was 34.3, 27.1, and 13.1%, respectively. The mean intensity of pain was 2.3 (±0.2) for neck, 2.0 (±0.2) for thoracic, and 1.3 (±0.1) for low back pain. The presence of two/three painful sites was reported by 21.7% of the adolescents. The frequency and severity of neck pain were inversely associated with global HRQoL in both the sexes. There is a strong inverse association between the number of painful sites and global HRQoL and domains.

Conclusion.

The presence and intensity of cervical pain and the number of painful regions were associated with lower HRQoL in adolescents, which is worrying due to the important relationship between back pain in the adolescence and in the adulthood.

Level of Evidence: 3
Hospital Variation in Renal Replacement Therapy for Sepsis in the United States
Authors: Valley Thomas S. , Nallamothu Brahmajee K. , Heung Michael , Iwashyna Theodore J. , Cooke Colin R.
Published: December 2017

Objectives:

Acute renal replacement therapy in patients with sepsis has increased dramatically with substantial costs. However, the extent of variability in use across hospitals—and whether greater use is associated with better outcomes—is unknown.

Design:

Retrospective cohort study.

Setting:

Nationwide Inpatient Sample in 2011.

Patients:

Eighteen years old and older with sepsis and acute kidney injury admitted to hospitals sampled by the Nationwide Inpatient Sample in 2011.

Interventions:

We estimated the risk- and reliability-adjusted rate of acute renal replacement therapy use for patients with sepsis and acute kidney injury at each hospital. We examined the association between hospital-specific renal replacement therapy rate and in-hospital mortality and hospital costs after adjusting for patient and hospital characteristics.

Measurements and Main Results:

We identified 293,899 hospitalizations with sepsis and acute kidney injury at 440 hospitals, of which 6.4% (n = 18,885) received renal replacement therapy. After risk and reliability adjustment, the median hospital renal replacement therapy rate for patients with sepsis and acute kidney injury was 3.6% (interquartile range, 2.9–4.5%). However, hospitals in the top quintile of renal replacement therapy use had rates ranging from 4.8% to 13.4%. There was no significant association between hospital-specific renal replacement therapy rate and in-hospital mortality (odds ratio per 1% increase in renal replacement therapy rate: 1.03; 95% CI, 0.99–1.07; p = 0.10). Hospital costs were significantly higher with increasing renal replacement therapy rates (absolute cost increase per 1% increase in renal replacement therapy rate: $1,316; 95% CI, $157–$2,475; p = 0.03).

Conclusions:

Use of renal replacement therapy in sepsis varied widely among nationally sampled hospitals without associated differences in mortality. Improving renal replacement standards for the initiation of therapy for sepsis may reduce healthcare costs without increasing mortality.