bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of the innovative exhaust air energy recovery heat exchanger
Authors: Borowski Marek , Jaszczur Marek , Satoła Daniel , Kleszcz Sławosz , Karch Michał
Published: November 2018

Heating, ventilation and air conditioning systems are responsible for a nearly 50% of total energy consumption in operated buildings. One of the most important parts of the ventilation system is an air handling unit with a heat exchanger for energy recovery which is responsible for effective and efficient energy recovery from exhaust air. Typically heat exchangers are characterised by the producers by heat and humidity recovery efficiency up to 90% and 75% respectively. But these very high values are usually evaluated under laboratory conditions without taking into account a dynamic change of outdoor and indoor air conditions significantly affecting the recovery efficiency. In this paper, results of thermal, humidity and enthalpy recover efficiency of innovative energy recovery exchanger have been presented. The analysed system allows adjustment of the humidity recovery especially useful in the winter period and forefends energy use for an anti-froze system of energy exchanger. Presented result show that analysed innovative system can achieve the value of thermal efficiency recovery higher than 90% and efficiency of humidity recovery about 80%. This is possible because the analysed system is able to work without the use of any primary source energy or other anti-freeze systems. Presented in this research unique solution is able to work without external anti-freeze systems even in extremely adverse outdoor air conditions such as minus 20°C and humidity 100% RH.
Effects of nanoparticles on hydraulic cavitation
Authors: Chen Min-rui , Qian Jin-yuan , Wu Zan , Yang Chen , Jin Zhi-jiang , Sunden Bengt
Published: November 2018

When liquids flowing through a throttling element, such as a perforated plate, the velocity increases and the pressure decreases. If the pressure is below the saturated vapor pressure, the liquid will vaporize into small bubbles, which is called hydraulic cavitation. In fact, vaporization nucleus is another crucial condition for vaporizing. The nanoparticles contained in the nanofluids play a significant role in vaporization of liquids. In this paper, the effects of the nanoparticles on hydraulic cavitation are investigated. Firstly, a geometric model of a pipe channel equipped with a perforated plate is established. Then with different nanoparticle volume fractions and diameters, the nanofluids flowing through the channel is numerically simulated based on a validated numerical method. The operation conditions, such as the temperature and the pressure ratio of inlet to outlet, are the considered variables. As a significant parameter, cavitation numbers under different operation conditions are achieved to investigate the effects of nanoparticles on hydraulic cavitation. Meanwhile, the contours are extracted to research the distribution of bubbles for further investigation. This study is of interests for researchers working on hydraulic cavitation or nanofluids.
Experimental validation of pressure drop models during flow boiling of R134a – effect of flow acceleration and entrainment
Authors: Muszynski Tomasz , Andrzejczyk Rafal , Dorao Carlos
Published: November 2018

A crucial step to assure proficient work of power and process apparatus is their proper design. A wide array of those devices operates within boiling or condensation of the working fluid to benefit from high heat transfer rates. Two-phase flows are associated with high heat transfer coefficients because of the latent heat of evaporation and high turbulence level between the liquid and the solid surface. Predicting heat transfer coefficient and pressure drop is a challenging task, and has been pursued by researchers for decades. In the case of diabatic flows, the total pressure drop is due to the change in kinetic and potential energy. The article presents detailed boiling pressure drops data for R134a at a saturation temperature of 19.4°C. Study cases have been set for a mass flux varying from 300 to 500 kg/m2s. Presented data along with the data reduction procedure was used to obtain the momentum pressure drop values during flow boiling. The study focuses on experimental values of momentum pressure drop component and its prediction based on various void fraction models and entrainment effects.
Analysis of flow through channel with mounted blades
Authors: Semkło Łukasz , Gierz Łukasz
Published: November 2018

Numerical analysis of parts of the installation for transporting the mixture. The mixture consists of sand, stones and water. The analysis concerns the possibility of reducing the flow velocity of the mixture in the installation by means of installing the blades. The article presents an analysis of 10 blades that have been simulated. Speed distributions are presented after passing through the blades and determined which slows the speed of the mixture to the best possible extent.
Viscous dissipation effect on laminar forced convection in a circular duct with adiabatic walls - preliminary numerical investigation
Authors: Teleszewski Tomasz Janusz
Published: November 2018

In this work, an analysis of laminar forced convection in a pipe with heated and adiabatic walls for a Newtonian fluid with constant properties is performed by taking the viscous dissipation into account when the axial heat conduction in the fluid is neglected. The Nusselt number versus the Brinkmann, which is based on the total wall heat flux density, have been investigated. In order to determine the temperature field, an analytical solution describing the velocity field in the pipe was used, while the energy equation was determined by the boundary element method (BEM). The results of the calculations of Nusselt numbers as a function of the Brinkman number for different thermal insulation heights to the diameter of the circular duct were presented in the form of diagrams.
Prediction and measurement of the aerodynamic performance of a wind turbine
Authors: Benim Ali Cemal , Diederich Michael , Gül Fethi
Published: November 2018

Aerodynamic behavior of a small wind turbine is analyzed, both experimentally and numerically. Mainly, an unsteady three-dimensional formulation is adopted, where the flow turbulence is modelled by an Improved Delayed Detached Eddy Simulation framework, using the four-equation transitional Shear Stress Transport model, as the turbulence model. A quite good agreement between the measurements and calculations is observed.
Temporal load resolution impact on PV/grid system energy flows
Authors: Jaszczur Marek , Hassan Qusay , Teneta Janusz
Published: November 2018

In this paper, an investigation of the electrical load temporal resolution on the PV/Grid energy system flows, and self-consumption is done in order to determine the optimum parameters for modelling and simulation. The analysed PV/Grid power systems include a photovoltaic system with the nominal power of Pmax@STC=1.5, 2.5, 3.5 kW without storage unit connected to the grid. The results show that the temporal load resolution may have a high impact on energy flows as well as can be a critical issue for the system analysis accuracy even for the single household. It has been found that the load temporal resolution for energy consumption of 1-min yields reliable results, while data resolutions of 5 and 15 min are still sufficient, however, in that case, the daily electrical energy flows and in consequence energy self-consumption estimation error for selected days may exceed 15%. Acquisition time step longer than 15-minutes may increase error above 20% and from the designer’s point of view should not be used. The high and low temporal resolution experimental data of the electricity consumption (load) for a household are available in digital form on the author’s website http://home.agh.edu.pl/jaszczur.
About the shortwave multiple reflections in an urban street canyon building related to three different European climates
Authors: Colucci Chiara , Mauri Luca , Vallati Andrea
Published: November 2018

Energy exchanges between buildings is affected by urban fabric. As a matter of fact, heat exchange between adjacent buildings is due to convective and radiative heat flows. The main parameters which influence these heat exchange mechanisms are due to climate conditions such as air temperatures/humidity, wind speed/direction and solar irradiance. Most building energy simulations are done on an independent single building with typical meteorological year (TMY). These TMY meteorological data cannot represent the state of the urban microclimate and rather ignores the microclimate influence on buildings adjacent to street canyons. However, solar radiation shading and reflection of the environment within the street canyons are important factors affecting the energy consumption of buildings. In this work, a building energy simulation tool is used to study the impact of multiple shortwave inter-reflections in an urban environment. A street canyon model validated in a previous work was modeled in TRNSYS in order to simulate the effects of the urban radiative trapping. An urban canyon with aspect ratio H/W=1 was chosen, with South-North orientation, with transparent/opaque surfaces ratio Atr/Aop=0.5 and 4 values (0.2, 0.4, 0.6, 0.8) of reflectance factor of the envelope surfaces. The goal is to characterize how solar absorption influence the urban energy requirements. The analysis was conducted for 3 cities in different climatic zones: Rome, Palermo and Krakow.
Thermal management of machine compartment in a built-in refrigerator
Authors: Devle Milind , Garg Ankur , Cavali Darci
Published: November 2018

In general a multi-door refrigerator machine compartment comprises of fan, condenser, compressor, control box, drain tray, and drain tubes. The performance of machine compartment depends upon the efficiency of heat extraction or heat exchange from heat generating components such as condenser and compressor. The efficiency of heat exchange can be improved by addressing two major factors, namely (1) Air bypass and (2) Hot air recirculation. The hot air recirculation in the machine compartment for builtin multi-door refrigerator configuration is the focus of this study. The results from Computational Fluid Dynamics (CFD) simulations show that efficiency of heat exchange for built-in application is lower than that for free-standing configuration. Recirculation of hot air and reduction in airflow are the two major factors which contribute towards the variation in machine compartment performance. The CFD simulations were coupled with Partial Factorial Design of Experiment (DoE) approach to systematically investigate the effect of variables such as (a) side gap and top gap between kitchen cabinetry and the refrigerator, (b) the baffle/flap (i.e. back and bottom of machine compartment) on the performance effectiveness of machine compartment. The results of the simulation provided critical design improvement directions resulting in performance improvement. Furthermore, the CFD simulation results were also compared to test data and the results compared favourably.
New start-up curves for a 200 MW steam boiler with natural circulation
Authors: Dzierwa Piotr
Published: November 2018

The paper shows the method of determining the start-up curves of a steam boiler, which enables its faster start-up. Faster temperature changes cause thermal stress, especially in thick-walled boiler elements. Critical elements that limit the rate of change of working fluid units include drums, outlet chamber, injection chamber, fresh steam superheater of steam coolers, tees and valve casings, rotor and turbine casing. The walls of these elements have the thickest walls due to the high pressure values occurring in them during operation. Allowable changes in temperature and pressure during start-up and shut-down can be determined by the European Standard EN 12952-3. The article shows how the start-up curves of a steam boiler can be determined using the European Standard and the method proposed by the author. Calculation results show that the starting time of the analyzed block can be significantly shortened.
Steady state CFD analysis of heat transfer coefficient in pressurised pipes of super-heater of OP210 steam boiler
Authors: Granda Mariusz
Published: November 2018

The aim of the paper is Computational Fluid Dynamics (CFD) analysis of Wall Heat Transfer Coefficient (WHTC) of pressurized pipe as a part of super-heater of the OP210 boiler. The object of the investigation is convection from saturated steam to the wall of the pipe, which works under high pressure and high temperature. The analysis is an approach to obtain exact solutions of WHTC according to the third type boundary condition compared to direct results from CFD analysis. The paper consists of three-step approach typical for CFD analysis: (i) Pre-Processing, the most elaborated part of the analysis where knowledge about super-heaters, turbulence, velocity profile is important to 3D model, mesh and boundary condition definition. (ii) Simulation of steady state turbulent flow until convergence criteria are met. (iii) Post-Processing where different approaches to the WHTC are shown in comparison. Also, the investigation includes two different types of meshes (where a different number of inflation layers are used) and comparison between k-epsilon and Solid Shear Stress (SST) turbulence model.
CFD modelling and validation of the rotary lobe compressed air expander
Authors: Kurkus-Gruszecka Michalina , Krawczyk Piotr , Łapka Piotr
Published: November 2018

The article covers the CFD analysis of the compressed air rotary lobe expander. Compressed air engines are commonly used in the explosion hazard zones, where the others power sources cannot be applied. The lobe construction seems to be cheaper solution in comparison with the classic turbine expanders at the corresponding power level.

In the paper the rotary lobe compressed air expander model was developed in the ANSYS CFX software. During implementation of the proposed numerical model the mesh motion problem was solved, which was challenging due to relatively small gaps between lobes and the housing as well as due to high rotary speed of lobes. What is more, the compressible fluid model was applied. Therefore, these conditions make the undertaken problem more complex and calculation more time consuming. Finally, the model was validated applying the catalogue data of the producer.

In the paper description of the developed model was presented. Then the results of simulations with their validation were shown which proved the correctness and accuracy of the model. The developed tool might be very useful for the further analysis of the expander including its optimization in terms of improvement of its efficiency or energy gain.
Verification of the heat transfer model for screw reactor
Authors: Levin Anatoliy , Kozlov Alexander , Svishchev Denis , Penzik Maxim
Published: November 2018

At present, the screw reactor pyrolysis is a promising and rapidly developing technology, because it helps obtain the end product, which is charcoal, tar, and synthesis gas. Additionally, pyrolysis can be considered as a preliminary stage for making the charcoal of the preset conversion for its further gasification when obtaining coal-derived gas. This research aims at establishing relationships between the operational parameters of pyrolysis and obtaining of the charcoal of preset conversion by means of mathematical modeling, full-scale experiment, and instrumental studies. Such comprehensive research ensures the accurate initial data, verification of the model, and optimal parameters for obtaining the product with preset properties as well as for further scaling of the reactor. In terms of design the pyrolyzer represents a recuperative heat exchanger where a mix of stack and recirculation gases is considered as a heat carrier. To prevent sintering of particles the screw transportation of fuel is used. The Comsol Multiphysics Software is used as a simulation environment. Heat exchange in the process of pyrolysis is simulated considering physical properties (porosity, permeability, etc.) of the medium. The constructed calculated mesh consisted of 604 thousand elements of three types (tetrahedrons, prisms and pyramids) and had the minimum size of 0.2 mm.
Comparison of dust emissions from an individual wood-fired boiler and dust emissions in the production of the same amount of heat in a combined heat and power plant
Authors: Rak Amadeusz , Kulesza Leszek
Published: November 2018

Comparison of dust emissions from an individual wood fired boiler (of various types) and of dust emissions during generation of the same amount of heat in a heat and power station were the aim of this work. For the purpose of the calculations the dust emissions from the heat and power station were assumed as the maximum permissible dust emissions, in line with the regulation of the Minister of Environment of 4 November 2014 on emission standards for certain types of installations, fuel combustion sources and waste incineration and co-incineration devices. The emissions of dusts for boilers were assumed based on available publications. For the purposes of the analysis, three boilers of 15 [kW] power were considered. Based on the obtained results it can be stated that the amounts of dust emitted by selected wood-fired boilers are not significantly different from the amount of dust emitted by a heat and power station for the same effect on the recipient’s side. Heating boilers of powers lower than 15 [kW] exist and for some of them the dust emissions are even smaller than for the boilers discussed herewith. The discussed boilers have heating efficiency of 86 %. If their efficiency were to be higher, the concentration of the dust would have been lower. The solid fuel (wood) fired boilers considered in this work are not the best ones on the market with respect the dust emissions. The ongoing development of the fuel combustion technology allows expecting even further reduction of emissions of dusts.
Prediction of a methane circular pool fire with fireFoam
Authors: Sedano Camilo , López Omar , Ladino Alexander , Muñoz Felipe
Published: November 2018

In the present work, the fireFoam solver was used with Large Eddy Simulation (LES) and the Eddy Dissipation Concept (EDC) for modelling a medium-scale methane pool fire. A convergence analysis performed, showed that a 2 Million elements three-dimensional mesh, is good enough to attain good numerical results. By comparing the numerical results obtained, with the experimental ones, as well as numerical results from previous studies, it was proven that the fireFoam solver is able to obtain satisfactory results.
Numerical research of solidification dynamics with anisotropy and thermal fluctuations
Authors: Smakulski Przemysław , Ishimoto Jun , Pietrowicz Sławomir
Published: November 2018

The influence of thermal fluctuations and anisotropy on the solidification process of a pure component is analyzed. It helps to understand the unstable freezing process where complicated structures such as dendrites could be formed due to a supercooling event reached during the cooling of the biological material. The study consists of mathematical modeling, validation with an analytical solution, and shows the influence of thermal noises on phase front dynamics. The analysis has been modeled in the framework of the Phase Field Method with Cahn-Hilliard formulation of a free energy functional [1]. The phase front is described by the Eulerian approach of fluid fields and formulated as a Phase Field scalar variable (order parameter) with a predefined, diffused boundary thickness. The results describe an influence scale onto directional phase front propagation dynamics, and how significant are stochastic thermal noises in micro-scale freezing.
Determination of heat losses through building partitions
Authors: Sobota Tomasz , Taler Jan
Published: November 2018

An numerical algorithm which can be use to calculate heat stream density transferred through wall with air void is presented . Some results of influence of thermal isolation on heat stream density transferred through the wall are presented too. The algorithm shown in this paper has general character and can be use to calculation loss of heat through the walls of block flats, furnaces , cold rooms and others objects and devices.
Transient heat transfer at fluid flow in a thick-walled pipeline
Authors: Sobota Tomasz , Taler Dawid , Lubecki Szczepan
Published: November 2018

The work aims to determine the transient temperature distribution of the medium and the pipeline wall using the finite difference method. Time courses of the temperature of the flowing medium and pipeline walls caused by a step change in temperature of the medium at the pipeline inlet, obtained by the numerical method, were compared with the courses calculated using strict analytical formulas. The numerical method of determining the transient distribution of temperature of medium and pipeline wall can be used in the analysis of heating and cooling of heating or steam pipelines with any changes in time of mass flow rate of the flowing medium or temperature of the medium at the inlet to the pipeline.
Influence of selected cycle components parameters on the supercritical CO2 power unit performance
Authors: Wołowicz Marcin , Milewski Jarosław , Ziembicki Gabriel
Published: November 2018

The paper presents the influence of selected components parameters on the performance of supercritical carbon dioxide power unit. For this analysis mathematical model of supercritical recompression Brayton cycle was created. The analysis took into consideration changes in the net cycle power and efficiency for different compressor inlet temperatures. The results were obtained for a fixed minimum pressure of 7.4 MPa and fixed recompression split ratio. The studies conducted in this paper included also consideration of sensitivity of the cycle efficiency to a change in recuperators heat transfer area. In order to determine how each recuperator influences the cycle performance, an analysis of efficiency dependence on the recuperators area was made. Another parameters that were investigated are to a change in turbine and compressors isentropic efficiency and their influence on the cycle efficiency. In the reference cycle, isentropic efficiencies were set up as 88% for both the main and recompression compressor, and 90% for the turbine. Since isentropic efficiency is a sort of measure of broadly defined quality of a turbine or compressor, including airfoil shape, sealing, etc., it may be a significant cost factor that should be considered during cycle design. Therefore, a sensitivity analysis of cycle efficiency to both compressors and turbine isentropic efficiencies was conducted.
Pulverized coal gasification with steam and flue gas
Authors: Zarzycki Robert
Published: November 2018

The study presents the concept and numerical calculations of the coal dust gasification in the entrained flow reactor with power of 16 MWt. The gasification process in the reactor can be performed in the atmosphere of O2, CO2 and H2O. The combustible gases obtained during gasification are composed mainly of CO and H2 and can be used to feed pulverized coal-fired boilers. Integration of the reactor (reactors) for coal dust gasification with the pulverized coal-fired boiler allows for improved flexibility, especially in the range of low loads if stabilization of coal dust combustion in pulverized-fuel burners or support for their work with ignition burners fed with gas or light fuel oil is necessary. The concept of the gasification reactor assumes strong eddy motion of the coal dust, which substantially allows for elongation of the time of fuel remaining in the reactor and obtaining a high reaction level. The concept of the entrained flow reactor presented in this study and the results of numerical calculations can be helpful for development of the devices with greater powers which in the nearest future should be integrated in the systems of pulverized coal-fired boilers in order to reduce their minimum load without using the ignition burners.
Proposed liquid CO2 cycle refrigeration system for heat hazard control
Authors: Zhai Xiaowei , Xu Yu , Yu Zhijin , Wang Kai
Published: November 2018

Liquid CO2 can absorb heat via phase change and generates cryogenic CO2 which can effectively solve the problem of thermal damage in the deep coal mining process. The CO2 cycle refrigeration device system is designed to effectively cool down the working surface of the mine in which CO2 is cyclically utilized. COMSOL Multiphysics simulation software is used to characterize the CO2 cycle refrigeration system in mine of the heat transfers process between CO2 and the air flow in tunnel. The results show that the reduction of steady air flow temperature reach at 8 °C in the tunnel by CO2 cycle refrigeration system before the air flow into work face. we analyzed the influence of main parameters on refrigeration system and gets the results:1) The refrigeration system get higher cooling efficiency of cryogenic CO2 when the ventilation velocity of local fan is increased, and the temperature of outlet CO2 and steady air flow in tunnel has increased; 2) Increasing the CO2 flow, the refrigeration effect of the system is enhanced obviously, but CO2 refrigeration capacity utilization ratio is reduced; 3) Increasing the length of helical tube would led to use CO2 refrigerating capacity more efficiently; 4) The cooling effect of the cooling system can be improved obviously by lowering the the CO2 cooling temperature.
A comprehensive study of a backlogging EOQ model with nonlinear heptagonal dense fuzzy environment
Authors: Maity Suman , Chakraborty Avishek , De Sujit Kumar , Mondal Sankar Prasad , Alam Shariful
Published: November 2018

This paper deals with an adaptation of an application of nonlinear heptagonal dense fuzzy number. The concept of linear and as well as non-linear for both symmetric and asymmetric heptagonal dense fuzzy number is introduced here. We develop a new ranking method for non-linear heptagonal dense fuzzy number also. Considering a backorder inventory model with non-linear heptagonal dense fuzzy demand rate we have utilized a modified centroid method for defuzzification. For decision maker’s aspects, numerical examples, comparative study with other dense fuzzy numbers and a sensitivity analysis show the superiority of the nonlinear heptagonal dense fuzzy number. Finally, graphical illustrations are made to justify the model followed by a conclusion.
Role of Cross-training in Orthopaedic Injuries and Healthcare Burden in Masters Swimmers
Authors: Baker Brett , Lapierre Stephanie , Tanaka Hirofumi
Published: November 2018

We determined whether the incidence of injuries would increase with advancing age and whether the participation in cross-training would be related to a decreased rate of injuries and healthcare costs in Masters swimmers. A total of 499 swimmers (55±14 years of age) belonging to US Masters Swimming completed a comprehensive questionnaire that included questions regarding their medical history as well as their training history. In average, swimmers had been training for 13±12 years, and 35, 40, and 47% participated in running, cycling, and dryland resistance training, respectively. According to the logistic regression, prevalence of injuries increased significantly but modestly with advancing age (p<0.05). Linear regression analysis showed that for every 1 month increase in the length of injury, healthcare costs increased by 7.4% (p<0.05). Linear regression and logistic regression analyses determined that overall volume of swimming training was not related to age or incidence of injuries, respectively. Multinomial logistic regression analyses using age and sex as predictors demonstrated that the odds of reporting a swim-related injury were significantly lower for individuals who participated in any number of cross-training activities compared with those who do not cross-train (p<0.05). Regular participation in any cross-training modality was inversely related to age (p<0.05). We concluded that the diversification of the overall training program by incorporating cross-training may be an important strategy to reduce sport-specific injuries among Masters athletes.
Spinal Injections, Epidural Neurolysis and Denervation for Specific Low Back Pain and Sciatica
Authors: Veihelmann Andreas
Published: November 2018

Background Many members of the adult population suffer acute low back pain at some stage in life. A specific cause is found in only a rather small number of these patients. Some of the patients develop chronic low back pain and this is a major source of disability. On the other hand, there has been a great increase in Germany in the number of spinal operations due to degenerative spine disease and, in turn, unnecessary surgery on the spine is under debate.

Methods This is a narrative review of different minimally invasive spine procedures in the treatment of specific low back pain. The effectiveness of spinal injections, radiofrequency of the facet joints as well as epidural adhesiolysis/neurolysis are described. An analysis of the literature was performed via PubMed, Medline and the Cochrane Database.

Results Facet-, epidural and intradiscal steroid injections for specific pain generators in the degenerative spine show different short- and long-term results; they are able to improve low back pain in specific patients with chronic low back pain and may be able to prevent some of these patients from having to undergo open surgery. Furthermore, there are promising results from interventions such as epidural neurolysis for sciatica and radiofrequency of the medial branch of the dorsal root for the treatment of axial facet-related back pain. Facet and intradiscal steroid injections give only short-term effects in axial low back pain and should therefore only be considered reluctantly, whereas the different forms of epidural steroid injections in patients with sciatica due to radicular compression offer a well proven adjuvant treatment option within a conservative therapeutic regimen. The overview of the literature with the use of different steroids has shown that use of non-particulate steroids show better results with respect to the safety and avoidance of major complications, especially when used at the cervical spine. However, in Germany the use of these steroids is still off label and patients have to give informed consent prior to injection. In summary, careful use of spinal injections and interventions within a conservative physiotherapeutic regimen seem to improve chronic back pain and, in turn, to be able to prevent some patients from having to undergo spine surgery.
Unsymmetrical Difunctionalization of Two Different C–H Bonds in One Pot Under Transition-Metal Catalysis
Authors: Murai Masahito , Takai Kazuhiko
Published: November 2018

Recent advancements in unsymmetrical difunctionalization based on the substitution of two different C–H bonds in one-pot are described. Due to the difficulty of controlling reactivity and selectivity, multi-functionalization via substitution of several C–H bonds to install different functional groups has been limited until recently, in comparison with well-studied functionalization via sequential addition to unsaturated π-bonds. This difunctionalization protocol provides an efficient and rapid approach to a library of structurally complicated target molecules through the formation of multiple C–X bonds with high atom- and step-economy.

1 Introduction

2 ortho-Selective Functionalization of Two Different C–H Bonds
Relative to the Directing Group

2.1 Unsymmetrical Difunctionalization with the Introduction of Similar Functional Groups

2.2 Unsymmetrical Difunctionalization with the Introduction of Different Functional Groups

2.3 ortho-Selective Unsymmetrical Difunctionalization Promoted by Two Different Directing Groups Appearing During the Progress of the Reaction

3 ortho/meta-Selective C–H Bond Difunctionalization Relative to the Directing Group

4 Sequential Difunctionalization of Fused Aromatic Compounds and Heterocycles

5 Summary and Outlook
Isolated Intraspinal Extradural Tubercular Lesion without Osseous Involvement
Authors: Pandey Sharad , Pandey Deepa , Singh Kulwant , Sharma Vivek , Ghosh Amrita
Published: November 2018

Tuberculosis (TB) continues to be a major public health problem in developing countries. Approximately 10% of patients with extrapulmonary TB have skeletal involvement. The spine is the most commonly affected skeletal site. The neurologic manifestations of spinal TB are most often secondary to bone involvement but can also be due to neural and perineural tissues involvement. TB may involve any level from the cervical to lumbosacral region. Extradural tubercular granuloma without vertebral involvement is uncommon. The authors reported an uncommon case of isolated intraspinal extradural TB lesion without osseous involvement of the thoracic spine in an adult man. Surgical intervention along with chemotherapy is one of the preferred treatments for intraspinal extradural tubercular lesion.
Reconstruction of a Large Full-Thickness Alar Defect Using an Extended Free Composite Flap from the Pinna: A Case Report
Authors: Vlachogiorgos Apostolos , Grecu Titus-Andrei , Salibi Andrej , Oudit Deemesh
Published: November 2018

Alar reconstruction can pose a challenging task in reconstructive surgery. Herein, we describe a case of a large full-thickness alar defect (involving the full- thickness of the left ala, 50% of the tip of the nose and extending over the left nasal sidewall and cheek) that was reconstructed using a contralateral free composite pinna flap, which extended into the right temple. A 70-year-old man with a squamous cell carcinoma to the left ala underwent surgical excision and immediate reconstruction with an extended contralateral free composite pinna flap based on a branch of the right superficial temporal artery supplying the helical root and the skin paddle of the supra-auricular area. The patient had an uneventful recovery and the result was aesthetically pleasing without compromising the nostril or the external nasal valve. Based on this case, a free composite flap incorporating the contralateral root of helix and adjacent tissue from the temporal region is an option that could be used in a single-staged procedure for reconstruction of large full-thickness alar defects. One of the challenges of performing free flaps in this area is the paucity of suitable recipient veins. This can be reliably addressed with a vein graft.
Comparison of ACUITY, CRUSADE, and GRACE Risk Scales for Predicting Clinical Outcomes in Patients Treated with Dual-Antiplatelet Therapy
Authors: Choi Sun , Kim Moo , Serebruany Victor
Published: November 2018

Several reliable scales have been proposed for the management and prognosis in patients with acute coronary syndromes (ACS) treated with dual-antiplatelet therapy (DAPT). We sought to compare the performance of three conventional risk scores to predict major bleeding (MB; such as ACUITY or CRUSADE), or major adverse cardiovascular event (MACE for GRACE). This study included 904 consecutive post-ACS patients from the single Korean study center who underwent coronary interventions, and were treated with DAPT. All three scores were calculated based on admission data. MB and MACE were collected at 30-day and 1-year follow-ups. MB was defined according to the Bleeding Academic Research Consortium (BARC) criteria (types 3–5), and MACE included all-cause death, myocardial infarction, target vessel revascularization, and stroke. MB occurred in 114 patients (12.6%) during 30 days, and 65 patients (7.2%) from 30 days till 1-year follow-up. MACE occurred in 28 (3.1%) and 72 (8.0%) patients during 30 and 30 days till 1 year, respectively. For 30 days MB, the discriminatory ability of ACUITY (AUC: 0.83, 95% CI: 0.81–0.86) and CRUSADE (AUC: 0.82, 95% CI: 0.79–0.84) was similar, and more reliable than GRACE (AUC: 0.74, 95% CI: 0.71–0.77; p < 0.0001 and p = 0.002, respectively). The predictive value for 1-year MB was similar between ACUITY (AUC: 0.75, 95% CI: 0.72–0.78, p < 0.0001), CRUSADE (AUC: 0.70, 95% CI: 0.70–0.73, p < 0.0001), and GRACE (AUC: 0.70, 95% CI: 0.67–0.73, p < 0.0001) classifications. All three risk scales exhibited similar prediction for 30-day and 1-year MACE. We conclude that ACUITY and CRUSADE scores were superior to GRACE in predicting 30-day MB. However, all three risk scales were similarly useful for long-term MB, and MACE assessment.
Embolization for Hemoptysis—Angiographic Anatomy of Bronchial and Systemic Arteries
Authors: Chennur Vikash , Shashi Kumar , Ryan Stephen , Hadziomerovic Adnan , Gupta Ashish
Published: November 2018

Massive hemoptysis is a potentially fatal respiratory emergency. The majority of these patients are referred to interventional radiology for bronchial artery embolization (BAE). Immediate clinical success in stopping hemoptysis ranges from 70 to 99%. However, recurrent hemoptysis after BAE is seen in 10 to 55% patients. One of the main reasons for recurrence is incomplete embolization due to unidentified aberrant bronchial and/or non-bronchial systemic arterial supply. This pictorial essay aims to describe the normal and variant bronchial arterial anatomy and non-bronchial systemic arterial feeders to the lungs on conventional angiography; the knowledge of which is critical for interventional radiologists involved in the care of patients with hemoptysis.
Analog high resistance bilayer RRAM device for hardware acceleration of neuromorphic computation
Authors: Jacobs-Gedrim R. B. , Agarwal S. , Goeke R. S. , Smith C. , Finnegan P. S. , Niroula J. , Hughart D. R. , Kotula P. G. , James C. D. , Marinella M. J.
Published: November 2018

Analog nonvolatile resistive switching phenomena in metal oxides can potentially be used as a synaptic weight in hardware based neuromorphic computing accelerators. Single layer resistive random-access memory (RRAM) devices have switching currents in the greater than 1 mA range, effectively requiring too much energy for integration in a crossbar array based neural accelerator. This study details the fabrication and characterization of a bilayer RRAM device consisting of a Pt-TaOx-Al2O3-TiN stack which is designed for low current operation. This high resistance bilayer device reduces switching energy to ∼8 pJ during RESET and 15 pJ during SET, at the expense of increased operational noise. Noise increase is expected in this higher resistance device due to electron trapping in levels created by vacancies piling up at the interface between the Al2O3 and TaOx layer. As a result, the simulated performance of these devices used in training a neuromorphic accelerator on the MNIST dataset was 80%, significantly lower than required. Using the difference in current between two devices to represent a digit and using two digits per weight with a technique called periodic carry (for a total of 4 devices), a training accuracy of 93% could be achieved. The device and methods detailed here represent a necessary step toward the realization of energy efficient neuromorphic accelerators.
Carbonyl compounds of Tc, Re, and Bh: Electronic structure, bonding, and volatility
Authors: Pershina V. , Iliaš M.
Published: November 2018

Calculations of molecular properties of M(CO)5 and MH(CO)5, where M = Tc, Re, and Bh, and of the products of their decomposition, M(CO)4 and MH(CO)4, were performed using density functional theory and coupled-cluster methods implemented in the relativistic program suits such as ADF, DIRAC, and ReSpect. The calculated first M—CO bond dissociation energies (FBDEs) of Bh(CO)5 and BhH(CO)5 turned out to be significantly weaker than those of the corresponding Re homologs. The reason for that is the relativistic destabilization and expansion of the 6d AOs, responsible for weaker σ-forth and π-back donations in the Bh compounds. The relativistic FBDEs of M(CO)5 have, therefore, a Λ-shape behavior in the row Tc-Re-Bh, while the non-relativistic values increase toward Bh. Using the results of the molecular calculations and a molecule-slab interaction model, adsorption enthalpies, ΔHads, of group-7 carbonyl hydrides on quartz and Teflon were estimated for future gas-phase chromatography experiments. It was found that BhH(CO)5 should be almost as volatile as the homologs, although its interaction with the surfaces should be somewhat stronger than that of MH(CO)5 (M = Tc and Re), while the M(CO)4 (M = Tc, Re, and Bh) molecules should be non-volatile. It will, therefore, be difficult to distinguish between the group-7 MH(CO)5 species by measuring their ΔHads on surfaces of Teflon and quartz with an error bar of ±4 kJ/mol. The trends in properties and ΔHads of group-7 carbonyl hydrides are similar to those of group-8 carbonyls of Ru, Os, and Hs.
Overlapping growth windows to build complex oxide superlattices
Authors: Haislmaier Ryan C. , Lapano Jason , Yuan Yakun , Stone Greg , Dong Yongqi , Zhou Hua , Alem Nasim , Engel-Herbert Roman
Published: November 2018

Perovskite oxide superlattices are of particular interest due to novel phenomena emerging at interfaces which are beyond the bulk properties of the constituent layers. However, building perovskite superlattices comprised of stoichiometric layers with sharp interfaces has proven challenging. Here, the synthesis of a series of high quality (SrTiO3)n/(CaTiO3)n superlattice structures grown on LSAT substrates is demonstrated by employing hybrid molecular beam epitaxy, where Ti was supplied using metal-organic titanium tetraisopropoxide (TTIP), and Sr and Ca were supplied using conventional effusion cells. By careful adjustment of the cation fluxes of Sr and Ca with respect to the TTIP flux, the growth windows of SrTiO3 and CaTiO3 were overlapped, allowing us to grow the individual superlattice layers with self-regulated stoichiometry. Stable and repeatable reflection high-energy electron diffraction oscillations during the entire ∼2.5 h growth period indicated good source flux stability. The structural quality of the superlattice films were determined by scanning transmission electron microscopy and synchrotron-based X-ray diffraction, revealing periodic, phase pure, homogenous superlattice structures with abrupt interfaces. Utilization of perovskite stoichiometric growth windows offers great potential for accessing and realizing interface driven phenomena in versatile perovskite superlattice materials with chemistries beyond titanates.
More thorough washing protocols reveal a new mechanism for antimicrobial materials
Authors: Liebendorfer Adam
Published: November 2018

Antifungal polyene drugs covalently bound to biomedical materials act through a desorption and physisorption mechanism rather than their oft-cited contact killing method.
Supernova, nuclear synthesis, fluid instabilities, and interfacial mixing
Authors: Abarzhi Snezhana I. , Bhowmick Aklant K. , Naveh Annie , Pandian Arun , Swisher Nora C. , Stellingwerf Robert F. , Arnett W. David
Published: November 2018

Supernovae and their remnants are a central problem in astrophysics due to their role in the stellar evolution and nuclear synthesis. A supernova’s explosion is driven by a blast wave causing the development of Rayleigh–Taylor and Richtmyer–Meshkov instabilities and leading to intensive interfacial mixing of materials of a progenitor star. Rayleigh–Taylor and Richtmyer–Meshkov mixing breaks spherical symmetry of a star and provides conditions for synthesis of heavy mass elements in addition to light mass elements synthesized in the star before its explosion. By focusing on hydrodynamic aspects of the problem, we apply group theory analysis to identify the properties of Rayleigh–Taylor and Richtmyer–Meshkov dynamics with variable acceleration, discover subdiffusive character of the blast wave-induced interfacial mixing, and reveal the mechanism of energy accumulation and transport at small scales in supernovae.
Communicating uncertainty in policy analysis
Authors: Manski Charles F.
Published: November 2018

The term “policy analysis” describes scientific evaluations of the impacts of past public policies and predictions of the outcomes of potential future policies. A prevalent practice has been to report policy analysis with incredible certitude. That is, exact predictions of policy outcomes are routine, while expressions of uncertainty are rare. However, predictions and estimates often are fragile, resting on unsupported assumptions and limited data. Therefore, the expressed certitude is not credible. This paper summarizes my work documenting incredible certitude and calling for transparent communication of uncertainty. I present a typology of practices that contribute to incredible certitude, give illustrative examples, and offer suggestions on how to communicate uncertainty.
Quantifying the role of mineral bridges on the fracture resistance of nacre-like composites
Authors: Grossman Madeleine , Bouville Florian , Masania Kunal , Studart André R.
Published: November 2018

Significance

Nacre, commonly called mother of pearl, is a biological composite that displays an exceptional combination of strength and noncatastrophic fracture behavior. The quantitative understanding of the structure–property correlations observed in nacre could provide powerful guidelines for the design of lightweight composite materials. By fabricating nacre-like brick-and-mortar composites from aligned alumina microplatelets interconnected by titania mineral bridges, we have been able to isolate and quantify the influence of mineral bridge density on the composite’s fracture properties. Because the model synthetic material is structured from ceramic constituents at the same length scale as biological nacre, it sheds light on the fundamental role of mineral bridges in natural brick-and-mortar structures, while also demonstrating outstanding mechanical properties.
Scientific communication in a post-truth society
Authors: Iyengar Shanto , Massey Douglas S.
Published: November 2018

Within the scientific community, much attention has focused on improving communications between scientists, policy makers, and the public. To date, efforts have centered on improving the content, accessibility, and delivery of scientific communications. Here we argue that in the current political and media environment faulty communication is no longer the core of the problem. Distrust in the scientific enterprise and misperceptions of scientific knowledge increasingly stem less from problems of communication and more from the widespread dissemination of misleading and biased information. We describe the profound structural shifts in the media environment that have occurred in recent decades and their connection to public policy decisions and technological changes. We explain how these shifts have enabled unscrupulous actors with ulterior motives increasingly to circulate fake news, misinformation, and disinformation with the help of trolls, bots, and respondent-driven algorithms. We document the high degree of partisan animosity, implicit ideological bias, political polarization, and politically motivated reasoning that now prevail in the public sphere and offer an actual example of how clearly stated scientific conclusions can be systematically perverted in the media through an internet-based campaign of disinformation and misinformation. We suggest that, in addition to attending to the clarity of their communications, scientists must also develop online strategies to counteract campaigns of misinformation and disinformation that will inevitably follow the release of findings threatening to partisans on either end of the political spectrum.