bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric generator at optimal power with external and internal irreversibilities
Authors: Kaur Jasleen , Johal Ramandeep S.
Published: September 2019

The exact power optimization of a thermoelectric generator is performed under the simultaneous presence of internal and external irreversibilities—modeled as nonideal thermal contacts and Joule heating, respectively. We consider a modification of the constant properties model whereby thermal conductivity of the thermoelectric material has spatial dependence, giving an asymmetric fraction of the Joule heat dumped in each reservoir. In particular, with a linear form of this dependence, the heat leakage term drops out as well as Joule heat is dumped only on one side. Exact expressions for efficiency at maximum power in each of these regimes are derived and are compared at thermal impedance matching and close to equilibrium, where interesting, stepwise changes in efficiency at maximum power are observed. The present analysis leads to the inference that higher values of efficiency at maximum power are obtained when both internal and external irreversibilities are taken on the hot side.
Theoretical investigations on melting/crystallization kinetics in overheated/overcooled aluminum at high pressures
Authors: Xiang Meizhen , Jiang Songqing , Chen Jun
Published: September 2019

In this study, we developed a theoretical model that explores material melting and crystallization kinetics at high pressures by combining the Kolmogorov-Johnson-Mehl-Avrami kinetics model with equations pulled from hydrodynamic and thermodynamic theories. Our model only requires two inputs: an equilibrium melting curve and an equation of state, both of which can be derived empirically through experiments. We use our model to investigate the melting and crystallization behaviors of aluminum at high pressures. At a constant homologous temperature, our model predicts that melting rates will increase, crystallization growth rates will decrease, and the minimum isothermal crystallization time will increase as pressure increases. Additionally, higher pressures also reduce the critical homologous temperature at which the isothermal crystallization time is at the minimum.
Triplet excitation energies from multiconfigurational short-range density-functional theory response calculations
Authors: Kjellgren Erik Rosendahl , Hedegård Erik Donovan , Jensen Hans Jørgen Aagaard
Published: September 2019

Linear response theory for the multiconfigurational short-range density functional theory (MC–srDFT) model is extended to triplet response with a singlet reference wave function. The triplet linear response equations for MC–srDFT are derived for a general hybrid srGGA functional and implemented in the Dalton program. Triplet excitation energies are benchmarked against the CC3 model of coupled cluster theory and the complete-active-space second-order perturbation theory using three different short-range functionals (srLDA, srPBE, and srPBE0), both with full linear response and employing the generalized Tamm-Dancoff approximation (gTDA). We find that using gTDA is required for obtaining reliable triplet excitations; for the CAS–srPBE model, the mean absolute deviation decreases from 0.40 eV to 0.26 eV, and for the CAS–srLDA model, it decreases from 0.29 eV to 0.21 eV. As expected, the CAS–srDFT model is found to be superior to the HF–srDFT model when analyzing the calculated triplet excitations for molecules in the benchmark set where increased static correlation is expected.
Argon-neon binary diagram and ArNe2 Laves phase
Authors: Dewaele Agnès , Rosa Angelika D. , Guignot Nicolas
Published: September 2019

Mixtures of argon and neon have been experimentally studied under high pressure. One stoichiometric compound, with ArNe2 composition, is observed in this system. It is a Laves phase with a hexagonal MgZn2 structure, stable up to at least 65 GPa, the highest pressure reached in the experiments. Its equation of state follows closely the one of an ideal Ar+2Ne mixture. The binary phase diagram of the Ar–Ne system resembles the diagram predicted for hard sphere mixtures with a similar atomic radius ratio, suggesting that no electronic interactions appear in this system in this pressure range. ArNe2 can be a convenient quasihydrostatic pressure transmitting medium under moderate pressure.
Spin-orbit coupling and vibronic transitions of two Ce(C4H6) isomers probed by mass-analyzed threshold ionization and relativistic quantum computation
Authors: Zhang Yuchen , Cao Wenjin , Yang Dong-Sheng
Published: September 2019

Ce atom reactions with ethylene, 2-butene, and isobutene are carried out in a pulsed laser vaporization molecule beam source. Ce-containing species are observed with time-of-flight mass spectrometry, and Ce(C4H6) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and relativistic quantum chemical calculations. Two structural isomers are identified for Ce(C4H6): one is the tetrahedronlike Ce[C(CH2)3] in C3v symmetry and the other is the five-membered metallocyclic Ce(CH2CHCHCH2) in Cs. The MATI spectrum of the C3v isomer exhibits two vibronic band systems separated by 88 cm−1, while that of the Cs isomer displays three split by 60 and 101 cm−1. The multiple band systems are attributed to spin-orbit splitting and vibronic transitions involving metal-hydrocarbon and hydrocarbon-based vibrations. The splitting in the C3v isomer arises from interactions of two triplet and two singlet states at the lowest energies, while each splitting in the Cs isomer involves two triplets and a singlet. Although the Ce atom has ground electron configuration 4f15d16s2, Ce valence electron configurations in both isomers are 4f16s1 in the neutral ground state and 4f1 in the ion. The remaining Ce 5d electrons in the isolated atom are spin paired in molecular orbitals that are a bonding combination between Ce 5dπ and hydrocarbon π* orbitals.
Safavid Iran and the “Turkish Question” or How to Avoid a War on Multiple Fronts
Authors: Matthee Rudi
Published: September 2019

This essay parts with the compartmentalized way in which scholarship tends to view Iran’s military predicament in the Safavid era by examining the perennial threat the Ottomans posed to the country largely in isolation from the recurring conflict between the Safavids and their other main adversaries, the Mughals and Uzbeks, respectively. The security dilemma facing Safavid Iran, it is argued here, was acute as well as multifaceted, and should be approached as such. All three of its direct neighbors were Sunni and two, the Ottomans and the Mughals, were capable of mobilizing far greater military resources than Iran. The main strategic concern of the Safavids was to prevent these neighbors from joining forces and engaging them in a two-front war. This study examines balancing the strategies employed by the three most consequential Safavid shahs, Esma‘il I (1501‒24), Tahmasb (1524‒76), and ‘Abbas I (1587‒1629), to avoid becoming the target of a simultaneous or combined assault by their neighbors. This analysis provides the backdrop to the rational decision the Safavids made in 1639—to end the threat of a two-front war by concluding a lasting peace accord with their most formidable enemies, the Ottomans.
International crop trade networks: the impact of shocks and cascades
Authors: Burkholz Rebekka , Schweitzer Frank
Published: September 2019

Analyzing available FAO data from 176 countries over 21 years, we observe an increase of complexity in the international trade of maize, rice, soy, and wheat. A larger number of countries play a role as producers or intermediaries, either for trade or food processing. In consequence, we find that the trade networks become more prone to failure cascades caused by exogenous shocks. In our model, countries compensate for demand deficits by imposing export restrictions. To capture these, we construct higher-order trade dependency networks for the different crops and years. These networks reveal hidden dependencies between countries and provide an estimate of necessary stock reserves to protect countries from cascading export restrictions. They differ substantially from first-order networks that do not take cascading effects into account. We find rice trade most prone to cascading export restrictions. A great number of Asian and African countries are most exposed to cascades. Noticeably, the main suppliers are similar for most of the crops: USA, Canada, Argentina, Brazil, and India. While shocks in the USA mainly affect South America and several Asian countries, the south of Africa is primarily dependent on American and Asian exporters. The north of Africa depends strongly on Europe, in particular via wheat imports.
Cold waves are getting milder in the northern midlatitudes
Authors: van Oldenborgh Geert Jan , Mitchell-Larson Eli , Vecchi Gabriel A , de Vries Hylke , Vautard Robert , Otto Friederike
Published: September 2019

The strong two-day cold wave in the midwestern United States in January 2019 again ignited the discussion as to whether cold waves are getting more severe or not as a result of Arctic amplification due to climate change. Assessing the evolution of cold waves in the northern hemisphere midlatitudes in the observations has been difficult because the variability of cold waves is large compared to anthropogenic warming. In order to detect changes in cold spells, two complementary ways to optimise the signal-to-noise ratio are employed: multi-decadal series at individual stations, and for shorter time periods by using spatially aggregated measures. Global warming is now strong enough to make trends clear at individual stations when considering long enough (>50 yr) records of daily minimum and maximum temperature. Calculating the land area that has temperatures below the 1-in-10 year return value (defined over 1951–1980) enables us to investigate trends over a shorter time horizon. The long-term station data have strong decreases everywhere in the lowest minimum temperature. Warming trends in the lowest maximum temperature are smaller over most of the Northern Hemisphere, with dataset-dependent indications of possible negative trends in parts of the United States and Mexico. Considering the area experiencing cold waves over the last decades, the most notable feature is a sharp decline of this area since the 1980s. The natural variability is still so large that it is possible to arbitrarily select starting dates after the decline for which the trend is slightly positive in smaller regions like North America or Europe. However, these values are within uncertainties compatible with a steady decline and have differing starting dates in North America and Europe. An analysis of the entire northern midlatitudes confirms the steady decrease in severity and frequency of cold waves over the last decades in the observations.
Bending analysis of skew ribbed plates with a meshfree method
Authors: Qin Xia , Liu Shan Shan , Peng Lin-Xin
Published: September 2019

Based on the first - order shear deformation theory (FSDT), a meshless method for solving the free vibration problem of the skew ribbed plates is proposed. The plates and ribs are discretized with a series of points to obtain a meshless model of the ribbed plate by simulating the ribs with beams. The FSDT and the moving least - squares approximation are used to establish the displacement field. The displacement fields of the stiffener can be expressed in terms of the mid-surface displacement of the plate by imposing displacement compatible conditions between the plate and the stiffener. Then the stiffness equation of the entire skew ribbed plate can be derived by superimposing the strain energy of plate and stiffener. And the boundary condition is introduced by the full transformation method. Several examples are calculated, and the results given by the proposed method are compared with those from other researchers or ABAQUS. The results show that the method can effectively analyze the bending problem of the skew ribbed plate, and it avoids redistribution of plate nodes when rib position changes.
Rib layout optimization of stiffened square plates based on a meshfree model and a hybrid genetic algorithm
Authors: Li Linyuan , Peng L X
Published: September 2019

In order to minimize the central deflection of stiffened square plates under different loads, stiffener/rib layout optimization of stiffened plate is studied in the present work based on meshfree method and a hybrid genetic algorithm. The stiffened plates are composed of flat plates and straight beams with constant cross section. In order to combine the flat plates and beams, are introduced. The calculate method of the stiffened plate is the meshfree method, and the ribs can be placed beyond mesh lines. During the entire process of rib layout optimization, no remeshing of the plate is required, which is convenient in programming and cost-efficient in computation. The optimization is carried out through the hybrid genetic algorithm which combines the genetic algorithm (GA) and the controlled random search algorithm. The controlled random search algorithm can effectively shorten the computation time of the genetic algorithm and increase the probability to find the efficient points. The validity and adaptability of the proposed method are tested by calculating several numerical examples.
Stiffness and damping effects of the rhombic piezoelectric stack transducer with a negative capacitance shunt
Authors: Yan B , Zheng W , Zhou S , Wu C
Published: September 2019

The piezoelectric shunt damping (PSD) is widely utilized to control structural vibrations based on its damping performance. Unlike previous studies, this work considers the stiffness and damping effects of a rhombic piezoelectric stack transducer with a negative capacitance shunt. The piezoelectric shunt stiffness (PSS) and the PSD concepts are proposed and theoretically modelled to investigate the stiffness and damping performance. The piezoelectric stack transducer with a negative capacitance can achieve both negative and positive stiffnesses to tune the natural frequency of the host structure. The root locus methods are utilized to judge the stability of the system. Both numerical simulation and experimental results demonstrate that the negative stiffness and the positive stiffness of the system greatly depend on the negative capacitance, while the damping depends on the resistance.
The thermal effect on dynamic characteristics of composite material pipe conveying fluid
Authors: Cai Su , Fang Bo
Published: September 2019

Based on thermoelasticity, the composite material pipe is studied in this paper with the variation of thermal expansion coefficient and temperature. Considering the thermal effect, a model called elastic Bernoulli-Euler beams is developed to analysis the buckling and vibration. The partial differential equations are established by using Hamiltonian principle. The static post-buckling problem is studied by eigenvalue method after Galerkin method. By harmonic balance method, the approximate solution of strong nonlinear vibration is obtained. The effect of thermal effect on vibration is also focused. The simulation shows that the thermal effects make conveyor pipes more vulnerable to instability, and has obvious influence on the dynamic characteristics. The research content is more practical than the dynamic analysis of the conveyor pipe without considering the temperature effect.
Vibration analysis of a rotating axially functionally graded tapered beam with hollow circular cross-section
Authors: Dong Shipeng , Li Liang , Zhang Dingguo , Zhang Yang
Published: September 2019

In this paper, the free vibrations of a rotating axially functionally graded (FG) tapered cantilever beam with hollow circular cross-section attached to a rigid hub are studied. To capture the additional dynamic stiffening terms, the longitudinal shrinkage of the beam is considered. The dynamic governing equations are derived via employing the assumed modes method and Lagrange’s equations. Through ignoring the higher-order quantities, the first order approximate coupling (FOAC) dynamic model can be acquired. Based on the FOAC dynamic model, influences of the angular speed, the taper ratio, the hub radius, the slenderness ratio, and the functionally gradient index on natural frequencies are studied. Frequency veering and mode shape interaction of the system are discussed when the bending-stretching (B-S) mode coupling effect of the beam is considered.
Static and dynamic mechanical properties of impregnated carbon nanotube fiber
Authors: Wan Shan-Xiu , Yang Qing-Sheng
Published: September 2019

Carbon nanotube fiber (CNT fiber) with excellent electrical and mechanical properties, as well as stable thermal and chemical properties has great potential application in areas such as ultra-fine wires, ultra-light cables, sensors, composite materials, energy conversion and electro-actuation. In this paper, the static and dynamic mechanical properties of impregnated CNT fiber were studied through single and cyclic tensile experiments and continuous dynamic analysis (CDA).The dynamic properties of impregnated CNT fiber such as storage and loss modulus was obtained. In addition, the storage modulus and loss modulus of impregnated CNT fiber increases with the increase of loading frequency. The research work in this paper has an important reference value for the engineering applications of impregnated CNT fiber in the fields of sensors and composites.
Design and Analysis of Shape Memory Polymer Mast Base on Numerical Simulation Method
Authors: Liu Shuai , Yang Qing-Sheng
Published: September 2019

As a space deployable structure, the space masts are widely used in the aerospace field. In the article, a new shape memory polymer (SMP) mast structure was designed and the compression folding behaviours of the SMP mast was investigated. The mast can automatic deployment due to the shape recovery characteristics of SMPs. The thermodynamic model of SMPs were realized by the finite element method. The numerical simulation of the fold and deployment process of the SMP mast were carried out, and the geometric parameters (wall thickness) and the influence of temperature on the folding performance of the mast were also investigated. The results contribute to the design and application of novel SMP mast.
Investigation of mechanical properties of additive manufactured graphene-reinforced aluminium composites
Authors: Liu Li-Ya , Yang Qing-Sheng
Published: September 2019

Graphene considered as an ideal reinforcement for metal matrix composites (MMCs) because of its excellent optical, electrical and mechanical properties has important application prospects in materials science, micro-nano processing and so on. Meanwhile, additive manufactured MMCs becomes the hotspot of current research due to the advantages of precise and controllable structure and easy implementation of modularization. In this paper, a two-dimensional rate-dependent crystal plasticity model using the numerical model is developed to simulate the mechanical behaviors of additive manufactured graphene-reinforced aluminium matrix composites (AMCs) under tensile load in a mesoscale. The mechanical properties are described by varying the volume fractions and distribution patterns of graphene. The results verify that graphene is the main load-bearing part of AMCs. The volume fraction and distribution pattern of graphene play an important role in the crystal dislocation strengthening of AMCs. Moreover, it is proved that the additive manufactured graphene-reinforced AMCs have a potential improvement with increased graphene volume fraction and optimized geometric graphene parameters.
The lightweight topology optimization of multi-material structures with displacement constraints
Authors: Dai Zong-Jie , Ye Hong-Ling , Wang Wei-Wei , Sui Yun-Kang
Published: September 2019

Multi-material Topology Optimization is a simulation technique based on the principle of the finite element method which is able to determine the optimal distribution of two or more different materials in combination under thermal and mechanical loads. This paper develops a lightweight topology optimization formulation of multi-material structures considering displacement constraints based on independent, continuous and mapping (ICM) method. Furthermore, explicit expression of optimised formulation is derived, approximations of displacement and weight are given by the first and second order Taylor expansion. And the optimization problem is solved by sequential quadratic programming approach. The feasibility and effectiveness of proposed method are demonstrated by numerical examples. It is found that the best transfer path of load is provided using multi-material topology optimization. The results show that a clear topological structure is obtained and the best transfer path of load is provided after multi-material topology optimization. In addition, under the precondition of satisfying the displacement constraint condition, the weight of the optimized structure based on various materials is lighter. The weight of multi-material topology optimization structure decreases with the increase of displacement constraint. And the optimal topological structure of the multi-material is different with the component materials. Besides, the optimization model established by using the structural performance parameters as a constraint is more reliable and more suitable for practical engineering applications.
Effects of microstructural parameters on phase transition temperature of hydrogels in chemo-mechanical coupling fields
Authors: Li Tao , Yang Qing-Sheng
Published: September 2019

The stability of hydrogels can be considered as the stability of polymer networks of the gels. The external environment can lead to the change of the polymer networks stability and the phase transition of hydrogels occurs. In this paper, a new free density energy function considering the chain entanglements and functionality of junctions is presented via combining Gent hyperelastic model and Edwards-Vilgis slip-link model with Flory-Huggins theory. A numerical method is developed to solve the phase transition temperature of the hydrogels based on the given new free energy function. Influences of four microstructure parameters on phase transition temperature of hydrogels are investigated by taking PNIPAM hydrogel as an example. Analytical results show that the microstructure parameters might affect the phase transition of the hydrogels significantly.
Knowledge-guided lightweight method for large complex component based on geometric-stress feature correlation response
Authors: Hua Haiyan , Chen Xu , Lin Hua
Published: September 2019

Complex geometric features and stress features as well as their intricate relationships are the important factors causing the complexity of lightweight for large component. In order to better coordinate the stress distribution with lightweight goal, a knowledge-guided lightweight method based on geometric-stress feature correlation response is proposed. Multistage decomposition and three-steps feature express strategy is utilized to construct the geometric features relationship model firstly. By combining the influence significance for stress features with the association grade for geometric features, and reasoning under lightweight expectations, the geometric-stress correlation knowledge is extracted. Furthermore, a knowledge-guided lightweight algorithm integrated knowledge correlation response with intelligent searching is proposed. Finally, the lightweight of X-type caterpillar frame is taken as example to demonstrate the effectiveness of this method.
Harmonic modeling of vibration energy harvesting systems using extended impedance method
Authors: Gao Yiming , Zhao Bao , Wang Jiahua , Liang Junrui
Published: September 2019

Vibration energy harvesting (VEH) systems convert the mechanical vibration energy in AC form into storable electrical energy in DC form. The mechanical structure, electromechanical transducer, and power electronics are three necessary parts for realizing the electromechanical energy transduction and rectification. The difficulty was found in modeling the electromechanical joint dynamics, in particular, when complex mechanical dynamics or sophisticated electrical switching transient are involved. Harmonic analysis is proven to be an efficient tool for modeling such a multiple-field-coupled power conversion system. In this paper, we develop a multiple harmonics analysis for the piezoelectric energy harvesting systems based on the extended impedance method (EIM). This method was used in the analysis of nonlinear power electronic circuits, such as resonant inverters and dc-dc converters. The theoretical results at steady state are compared with the simulation results from the commercialized circuit simulation software. The new modeling technique provides an efficient tool for the customized design and holistic optimization of the vibration energy harvesting systems.
Reducing the drag of underwater vehicle in the shape of a small boat by using piezoelectric transducers
Authors: Zhang Lu , Shan Xiaobiao , Liu Yingxiang , Peng Gaoliang , Xie Tao
Published: September 2019

Reducing the flow resistance of moving underwater vehicles can improve their performance and reduce the energy consumption. This paper presents a method to interfere the turbulent boundary layer for achieving the drag reduction by using piezoelectric transducers. The transducer produces ultrasonic traveling waves vibration near the hull surface. The working frequency and the maximum vibration amplitude of the transducers placed in different locations were obtained through the structural dynamic analysis. The fluid-solid coupling simulations were performed to explore the reduction drag performance. The simulation results show that better drag reduction performance can be obtained when the angle between the vibration direction of the piezoelectric transducer and the flow direction is 67.62°. The method of using piezoelectric transducer vibration for drag reduction is proved to be feasible. The present work provides a valuable reference for the study of drag reduction of underwater vehicles.
Numerical simulation on the seismic performance of post-fire steel concrete frame joint bonded with steel
Authors: Wang J Y , Yue X C , Sun Y Z
Published: September 2019

Steel was used to reinforce the joint of the frame after fire, and the joint was subjected to low cyclic loading. The seismic behaviors including hysteretic curve, skeleton curve, energy dissipation and stress distribution were analyzed using the finite element method. The results show that the bearing capacity in the elastic stage is almost unchanged comparing with the non-reinforced joint, but the ultimate bearing capacity, energy dissipation capacity and ductility are all improved in different degrees. However, the strengthening effect is not unlimited with the increase of the thickness of bonded steel. The thickness of bonded steel should not exceed 6 mm considering the ultimate bearing capacity, energy dissipation capacity and stress distribution of the structure. The area of high stress zone increases with the increase of axial compression ratio.
Investigations on flexural wave propagation of a grillage structure using the multi-reflection method
Authors: Li Yanqiu , Zhou Runxin , Liu Liangmei , Chen Tao
Published: September 2019

The flexural wave propagation in a grillage structure with a propagating disturbance is studied firstly by the use of the multi-reflection method. The grillage structure consists of many beams intersecting each other at right angles. Each periodic binary beam consists of a finite repetition of alternating material A and material B. A propagating wave is incident upon a discontinuity of a beam along the x axis and gives rise to transmitted and reflected waves. Here all of the transmitted and reflected waves of given flexural wave incident upon the beam at some specified location are found and superposed, these waves travel to the other beams as a bending wave in the direction of their partially reflected and partially transmitted. Then the wave-fields of two beams along the y axis closest to external disturbance is set up, these two beams only need to consider the influence of bending waves on the x-beams on them. Next the wave-fields of two beams along the x axis closest to external disturbance is set up, the rest can be done in the same manner. Finally the wave-field of any beam at some specified location can be determined.
Ecotypic differentiation, hybridization and clonality facilitate the persistence of a cold-adapted sedge in European bogs
Authors: Schwarzer Christian , Joshi Jasmin
Published: September 2019

Recent research has shown that many cold-adapted species survived the last glacial maximum (LGM) in northern refugia. Whether this evolutionary history has had consequences for their genetic diversity and adaptive potential remains unknown. We sampled 14 populations of Carex limosa, a sedge specialized to bog ecosystems, along a latitudinal gradient from its Scandinavian core to the southern lowland range-margin in Germany. Using microsatellite and experimental common-garden data, we evaluated the impacts of global climate change along this gradient and assessed the conservation status of the southern marginal populations. Microsatellite data revealed two highly distinct genetic groups and hybrid individuals. In our common-garden experiment, the two groups showed divergent responses to increased nitrogen/phosphorus (N/P) availability, suggesting ecotypic differentiation. Each group formed genetically uniform populations at both northern and southern sampling areas. Mixed populations occurred throughout our sampling area, an area that was entirely glaciated during the LGM. The fragmented distribution implies allopatric divergence at geographically separated refugia that putatively differed in N/P availability. Molecular data and an observed low hybrid fecundity indicate the importance of clonal reproduction for hybrid populations. At the southern range-margin, however, all populations showed effects of clonality, lowered fecundity and low competitiveness, suggesting abiotic and biotic constraints to population persistence.
Effectiveness of Oral Vancomycin for Prevention of Healthcare Facility–Onset Clostridioides difficile Infection in Targeted Patients During Systemic Antibiotic Exposure
Authors: Johnson Steven W , Brown Shannon V , Priest David H
Published: September 2019

Background

Limited retrospective data suggest prophylactic oral vancomycin may prevent Clostridioides difficile infection (CDI). We sought to evaluate the effectiveness of oral vancomycin for the prevention of healthcare facility–onset CDI (HCFO-CDI) in targeted patients.

Methods

We conducted a randomized, prospective, open-label study at Novant Health Forsyth Medical Center in Winston-Salem, North Carolina, between October 2018 and April 2019. Included patients were randomized 1:1 to either oral vancomycin (dosed at 125 mg once daily while receiving systemic antibiotics and continued for 5 days postcompletion of systemic antibiotics [OVP]) or no prophylaxis. The primary endpoint was incidence of HCFO-CDI. Secondary endpoints included incidence of community-onset healthcare facility–associated CDI (CO-HCFA-CDI), incidence of vancomycin-resistant Enterococci (VRE) colonization after receiving OVP, adverse effects, and cost of OVP.

Results

A total of 100 patients were evaluated, 50 patients in each arm. Baseline and hospitalization characteristics were similar, except antibiotic exposure. No events of HCFO-CDI were noted in the OVP group compared with 6 (12%) in the no-prophylaxis group (P = .03). CO-HCFA-CDI was identified in 2 patients who were previously diagnosed with HCFO-CDI. No patients developed new VRE colonization, with only 1 patient reporting mild gastrointestinal side effects to OVP. A total of 600 doses of OVP were given during the study, with each patient receiving an average of 12 doses. Total acquisition cost of OVP was $1302, $26.04 per patient.

Conclusion

OVP appears to protect against HCFO-CDI during in-patient stay in targeted patients during systemic antibiotic exposure. Further prospective investigation is warranted.
Wolbachia megadiversity: 99% of these microorganismic manipulators unknown
Authors: Detcharoen Matsapume , Arthofer Wolfgang , Schlick-Steiner Birgit C , Steiner Florian M
Published: September 2019

Wolbachia (Alphaproteobacteria) are the most widespread endosymbionts of arthropods, manipulating their hosts by various means to maximize the number of host individuals infected. Based on quantitative analyzes of the published literature from Web of Science® and of DNA sequences of arthropod-hosted Wolbachia from GenBank, we made plausible that less than 1% of the expected 100 000 strains of Wolbachia in arthropods is known. Our findings suggest that more and globally better coordinated efforts in screening arthropods are needed to explore the true Wolbachia diversity and to help us understand the ecology and evolution of these host-endosymbiont interactions.
Impact of Multidomain Lifestyle Intervention on Frailty Through the Lens of Deficit Accumulation in Adults with Type 2 Diabetes Mellitus
Authors: Simpson Felicia R , Pajewski Nicholas M , Nicklas Barbara , Kritchevsky Stephen , Bertoni Alain , Ingram Frank , Ojeranti Daniel , Espeland Mark A ,   for the Indices for Accelerated Aging in Obesity and Diabetes Ancillary Study of the Action for Health in Diabetes (Look AHEAD) Trial
Published: September 2019

Background

Type 2 diabetes and obesity increase the accumulation of health deficits and may accelerate biological aging. Multidomain lifestyle interventions may mitigate against this.

Methods

Within a large, randomized clinical trial of intensive lifestyle intervention including caloric restriction, increased physical activity, dietary counseling, and risk factor monitoring compared with diabetes support and education, we examined the accumulation of health deficits across 8 years. We used two complementary frailty indices (FIs) based on deficit accumulation, one modeled on work in the Systolic Blood Pressure Intervention Trial and the other including additional deficits related to obesity and type 2 diabetes mellitus. Differences between intervention groups and their consistency among subgroups were assessed with re-randomization tests.

Results

Data from 4,859 adults (45–76 years at baseline, 59% female) were analyzed. Random assignment to intensive lifestyle intervention was associated with lower FI scores throughout follow-up as captured by areas under curves traced by longitudinal means (p ≤ .001), over which time mean (SE) differences between intervention groups averaged 5.8% (0.9%) and 5.4% (0.9%) for the two indices. At year 8, the percentage of participants classified as frail (FI > 0.21) was lower among intensive lifestyle intervention (39.8% and 54.5%) compared with diabetes support and education (42.7% and 60.9%) for both FIs (both p < .001). Intervention benefits were relatively greater for participants who were older, not obese, and without history of cardiovascular disease at baseline.

Conclusions

Eight years of multidomain lifestyle intervention create a buffer against the accumulation of age-related health deficits in overweight or obese adults with type 2 diabetes.

ClinicalTrials.gov Identifier: NCT00017953
Deformation of rhyolite lava crust associated with intermittent inner flow of lava: palaeomagnetic evidence
Authors: Uno Koji , Furukawa Kuniyuki , Nakai Kotaro , Kamio Takuma , Kanamaru Tatsuo
Published: September 2019

A palaeomagnetic study has been conducted to examine the deformation of thick crusts of rhyolite lava while its inner portions continue to flow. The Sanukayama rhyolite lava, which erupted in the Pleistocene in Kozushima Island, Japan, was chosen as the investigation site because of its well-exposed vertical lithofacies variations classified into three distinct zones (pumiceous, obsidian and crystalline). The targets of this study are the pumiceous and obsidian zones, which constitute the crust of the lava. Thermal demagnetization reveals three remanent magnetization components from the pumiceous and obsidian samples but only a single magnetization component from the inner crystalline rhyolite samples. Alternating field demagnetization is ineffective in isolating the magnetization components in the pumiceous and obsidian samples. The multiple components of remanent magnetization of the crust are interpreted to have been acquired during cooling as thermoremanent magnetizations. We suspect intermittent lava transport of the inner portions, the primary mode of rhyolite lava advancement, to be responsible for the presence of multiple components in pumice and obsidian of the lava crust. When the inner portions of the lava retain mobility to flow out of the crust, the solidified crust of the lava surface below the magnetite Curie temperature remains susceptible to deformation. Analysis of palaeomagnetic directions from the crust allows the deformation of the crust to be described in terms of rotation. Although the mode of rhyolite lava advancement is not well understood, because of its infrequent occurrence, our observations offer an important insight on how the mobile part of the lava is associated with the deformation of the crust during continued lava advance.
Total CD3 T Cells Are Necessary and Sufficient to Induce Colitis in Immunodeficient Mice With Dendritic Cell–Specific Deletion of TGFbR2: A Novel IBD Model to Study CD4 and CD8 T-Cell Interaction
Authors: Jamwal Deepa Rana , Marati Raji V , Harrison Christy A , Midura-Kiela Monica T , Figliuolo Paz Vanessa R , Besselsen David G , Ghishan Fayez K , Kiela Pawel R
Published: September 2019

Background

Inflammatory bowel disease (IBD) is a multifactorial disorder, with the innate and adaptive immune cells contributing to disease initiation and progression. However, the intricate cross-talk between immune cell lineages remains incompletely understood. The role of CD8+ T cells in IBD pathogenesis has been understudied, largely due to the lack of appropriate models.

Methods

We previously reported spontaneous colitis in mice with impaired TGFβ signaling due to dendritic cell–specific knockout of TGFbR2 (TGFβR2ΔDC). Here, we demonstrate that crossing TGFβR2ΔDC mice with a Rag1-/- background eliminates all symptoms of colitis and that adoptive transfer of unfractionated CD3+ splenocytes is sufficient to induce progressive colitis in Rag1-/-TGFβR2ΔDC mice.

Results

Both CD4+ and CD8+ T cells are required for the induction of colitis accompanied by activation of both T-cell lineages and DCs, increased expression of mucosal IFNγ, TNFα, IL6, IL1β, and IL12, and decreased frequencies of CD4+FoxP3+ regulatory T cells. Development of colitis required CD40L expression in CD4+ T cells, and the disease was partially ameliorated by IFNγ neutralization.

Conclusions

This novel model provides an important tool for studying IBD pathogenesis, in particular the complex interactions among innate and adaptive immune cells in a controlled fashion, and represents a valuable tool for preclinical evaluation of novel therapeutics.
Organic matter disappearance and production of short- and branched-chain fatty acids from selected fiber sources used in pet foods by a canine in vitro fermentation model1
Authors: Donadelli Renan A , Titgemeyer Evan C , Aldrich Charles G
Published: September 2019

Dietary fibers can influence a dog’s overall health, but high concentrations of soluble dietary fibers can cause soft stools. An in vitro model could be useful to predict the rate fibers are fermented once they reach the colon. Pet food companies are constantly searching for new ingredients to differentiate their products from competitors. Miscanthus grass (MG), pea fiber (PF), and sorghum bran (SB) are novel fiber sources that could be alternatives to standards like cellulose (CE) and beet pulp (BP). The objectives of the study were to determine the effects of fiber source on organic matter disappearance (OMD), estimated organic matter disappearance (EOMD), and fermentation end-product concentrations using an in vitro fermentation procedure and dog fecal inoculum. Total dietary fiber (TDF) residues from MG, CE, BP, PF, and SB were fermented in vitro with buffered dog feces. Fecal samples were collected and maintained in anaerobic conditions until the dilution and inoculation. Test tubes containing the fibrous substrates were incubated for 4, 8, and 12 h at 39 °C. Short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), OMD, and EOMD were determined for each fiber source and time point. Beet pulp had the highest OMD, EOMD, and SCFA production of all tested fiber sources (38.6% OMD, 26.2% EOMD, 2.72 mmol SCFA/g of substrate). Sorghum bran led to greater concentrations of BCFA (59.86 µmol/g of substrate) and intermediate OMD and EOMD compared to the other tested fibers. Cellulose and MG were poorly fermented with the lowest OMD, EOMD, SCFA, and BCFA compared to other fibers. In conclusion, MG could be used as an insoluble minimally fermentable replacement fiber for CE in dog foods.
Effect of stearic or oleic acid on milk performance and energy partitioning when fed in diets with low and high rumen-active unsaturated fatty acids in early lactation
Authors: Yanting Chen , Ma Guiling , Harrison Joseph H , Block Elliot
Published: September 2019

This experiment was conducted to determine the effects of stearic acid (SA; C18:0) or rumen-protected oleic acid (OA; C18:1 cis-9) on milk performance and energy partitioning of early lactation cows when supplemented in diets with low and high level of rumen unsaturated fatty acids (RUFA). In low RUFA experiment (LRUFA), FA supplement rich in either SA or calcium salts OA was added to a basal diet with a low concentration of RUFA (0.75% vs. 1.4%, LRUFA-SA vs. LRUFA-OA). In high RUFA experiment (HRUFA), 2% soybean oil was added to the diet fed in the LRUFA experiment. In each experiment, 30 multiparous cows were blocked by parity and predicted transmitting ability for milk yield and were randomly fed 1 of 2 treatment diets from 2 to 13 wk postpartum. In the LRUFA experiment, LRUFA-SA had 2.4 kg/d more dry matter intake (DMI) (P < 0.01), 3.8 kg/d more energy-corrected milk (P < 0.01), and 0.3% units more milk fat percentage (P < 0.01) and 0.2 kg/d more milk fat yield (P < 0.01). Dietary treatments did not affect body weight, energy balance, and energy intake partitioning into milk, maintenance, and body tissues (P > 0.1). In the HRUFA experiment, HRUFA-SA had 1.4 kg/d more DMI (P = 0.03) but similar milk and milk components yields (P > 0.1). HRUFA-SA had a tendency to gain more body weight (P = 0.07) and had more positive energy balance (P = 0.01) and decreased gross feed efficiency (milk yield/DMI) (P = 0.01). Consistently, HRUFA-SA increased intake energy partitioning into body tissues (P = 0.02) and decreased energy partitioning into milk (P = 0.01). In summary, SA supplementation had more DMI relative to OA, but the effects on milk and milk fat production were different and affected by the level of RUFA in the basal diet. In application, SA supplementation was more effective to improve milk production when included in the basal diet with the low RUFA.
Action of Metarhizium brunneum (Hypocreales: Clavicipitaceae) Against Organophosphate- and Pyrethroid-Resistant Aedes aegypti (Diptera: Culicidae) and the Synergistic Effects of Phenylthiourea
Authors: Prado Rodrigo , Macedo-Salles Pãmella A , Duprat Rodrigo C , Baptista Andrea R S , Feder Denise , Lima José Bento Pereira , Butt Tariq , Ratcliffe Norman A , Mello Cicero Brasileiro
Published: September 2019

Dengue, yellow fever, Zika, and chikungunya arboviruses are endemic in tropical countries and are transmitted by Aedes aegypti. Resistant populations of this mosquito against chemical insecticides are spreading worldwide. This study aimed to evaluate the biological effects of exposure of pesticide-sensitive Ae. aegypti larvae (Rockefeller) to conidia of the entomopathogen, Metarhizium brunneum, laboratory strains ARSEF 4556 and V275, and any synergistic activity of phenylthiourea (PTU). In addition, to investigate the nature of any cross-resistance mechanisms, these M. brunneum strains were tested against the Rockefeller larvae and two temephos- and deltamethrin-resistant wild mosquito populations from Rio de Janeiro. Treatment of Rockefeller larvae with 106 conidia/ml of ARSEF 4556 and V275 fungal strains resulted in significant decreased survival rates to 40 and 53.33%, respectively (P < 0.0001), compared with untreated controls. In contrast, exposure to 104 or 105 conidia/ml showed no such significant survival differences. However, the addition of PTU to the conidia in the bioassays significantly increased mortalities in all groups and induced a molt block. Experiments also showed no differences in Ae. aegypti mortalities between the fungal treated, wild pesticide-resistant populations and the Rockefeller sensitive strain. The results show the efficacy of M. brunneum in controlling Ae. aegypti larvae and the synergistic role of PTU in this process. Importantly, there was no indication of any cross-resistance mechanisms between Ae. aegypti sensitive or resistant to pesticides following treatment with the fungi. These results further support using M. brunneum as an alternative biological control agent against mosquito populations resistant to chemical insecticides.
Real-World Evidence of Differences in Biomarkers of Exposure to Select Harmful and Potentially Harmful Constituents and Biomarkers of Potential Harm Between Adult E-Vapor Users and Adult Cigarette Smokers
Authors: Oliveri Douglas , Liang Qiwei , Sarkar Mohamadi
Published: September 2019

Introduction

Real-world evidence regarding likely long-term health effects of e-vapor products (EVP) under actual use conditions relative to cigarette smoking is not well studied.

Methods

In this cross-sectional, observational study, biomarkers of exposure (BOE) to select harmful and potentially harmful constituents and biomarkers of potential harm (BOPH) relevant to smoking-related diseases were measured in exclusive adult EVP users (AEVP, n = 144) and exclusive adult cigarette smokers (AS, n = 73). AEVP used their own brand of EVP for 6+ months following 10+ years of cigarette smoking and AS smoked own brand of cigarettes for 10+ years. Subject recruitment and informed consent were obtained online and urine/blood samples were collected at local clinical laboratories, representing a new paradigm for collecting real-world evidence.

Results

The levels of total NNAL (NNK metabolite), 3-hydroxypropyl mercapturic acid (acrolein metabolite), and carboxyhemoglobin (carbon monoxide measure) were 46% to 86% lower in AEVP compared with AS (p ≤ .0001) as was nicotine equivalents (nicotine and its five metabolites; 36%, p < .01). The levels of some BOPH were significantly lower in AEVP compared with AS for 11-dehydrothromboxane-B2 (29%, p = .04; platelet activation), 8-epi-prostaglandin F2α (23%, p = .02; oxidative stress) and soluble intercellular adhesion molecule-1 (16%, p = .02; endothelial function).

Conclusions

This study demonstrates the feasibility of a new approach for collecting real-world evidence. Substantially lower levels of BOEs (NNK, nicotine, acrolein, carbon monoxide) and favorable differences in BOPHs (platelet activation, oxidative stress, endothelial function) suggest EVP users may have lower health risks than cigarette smokers.

Implications

Cigarette smoking causes serious diseases. Switching from a combustible tobacco product to a noncombustible product is a potential harm reduction pathway for adult smokers unable or unwilling to quit. Real-world evidence regarding the relative risk of EVP use compared with cigarettes is not well established. This study provides data specific to BOE to tobacco smoke constituents and biomarkers of potential harm collected under actual use conditions in a real-world setting. The totality of evidence suggests that exclusive EVP use may present lower health risk compared with smoking cigarettes.