bluuebunny/crossref_metadata_2025 huggingface dataset:
Device for Conductive Coatings Quality Control of Rocket and Space Technique Elements
Authors: Skvortsov B. V. , Samsonov A. S. , Borminskiy S. A. , Zhivonosnovskaya D. M.
Published: April 2019

The widespread use of cryogenic fuels in the aerospace industry necessitates additional thermal insulation of aircraft fuel tanks. At the same time a static charge may occur on the heat insulating layer during operation which can lead to an explosion if fuel leaks. To avoid such situations an antistatic conductive coating is applied to the insulation. The aim of the study is to develop a device for remote control of conductive coatings of aircraft fuel tanks which allows to quick find and mark damaged areas.

The developed method consists in changing the electrical capacitance between the conductive coating of the controlled object and the scanning electrode allowing to identify hazardous in terms of sparking closed shape defects. The basic technical requirements for the device were formed and the required minimum size of the monitored defect were indicated. The design features necessary for the implementation of the device were considered. A block diagram were developed on the basis of which an experimental bench for capacitive control were created which were is based on the bridge measurement method.

The article presents the results of the finite-difference calculation of the electric field in the structure of a capacitive sensor in the presence of a defect, the dependence of the capacitance of the sensor on its displacement over the defective area was also obtained. As the result of experimental studies the experimental data obtained confirmed the theoretical calculations and the correctness of the mathematical model with an accuracy of no worse than 5 %, the absolute error of fixing the defect ± 2 mm at a scanning speed of 0,02 m/s. Was shown that the total error of fixing the coordinates of the defect at different positions of the air gap sensor, temperature and scanning speed lies in the range of 1,5–6,5 mm. The materials presented in the article make it possible to increase flight safety by reducing the likelihood of sparking.
Model of Field Electron Emission from the Edge of Flat Graphene into Vacuum
Authors: Poklonski N. A. , Siahlo A. I. , Vyrko S. A. , Ratkevich S. V. , Vlassov A. T.
Published: April 2019

Graphene-based nanostructures are the promising materials for applications as electron emitters.

The aim of the work is to study the field electron emission from the edge of a single graphene plane.

In the semi-classical approximation, a model of field electron emission from the edge of a rectangular graphene sheet has been developed.

The current density of field electron emission into vacuum from the edge of a flat graphene sheet was calculated depending on the magnitude of the pulling electric field strength.

The analysis and comparison of limiting emission currents from graphene and from bulk systems have been carried out.

The results of the work can be used in the development of graphene-based field effect cathodes.
Features of the Surface and Subsurface Waves Application for Ultrasonic Evaluation of Physicomechanical Properties of Solids. Part 2. Strenghtned Inhomogeneous Surface Layer
Authors: Baev A. R. , Mayorov A. L , Levkovich N. V. , Asadchaya M. V.
Published: April 2019

The propagation of a pulsed signal of a surface wave over an object with a non-uniform surface layer, obtained, for example, as a result of surface hardening, with structural damage, is accompanied by the dispersion of the velocity of the wave carrying important information about the parameters of such a layer. The aim of the work is to study the relationship between the acoustic parameters of a pulsed acoustic signal of a surface and subsurface waves and the surface layer of steel specimens hardened by high-frequency hardening, and gray iron-chill. Features of the surface and subsurface waves application for ultrasonic evaluation of physicomechanical properties of solids. Strenghtned inhomogeneous surface layer.

A brief analysis of the known works on determining the depth of hardened surface layers by various methods, including high-frequency hardening, cementation, etc., is carried out. Based on the Oulder integral expression. The dependence connecting the wave velocity, its frequency, the depth of the hardened layer and the spatial distribution of hardness represented as a step with a changing slope of its side surface simulating the transition zone of the hardened layer are calculated.

Using the pulse method and low-aperture transducers with a frequency of 1−3.8 MHz, the dependences of the surface wave velocity on the cutting height of a layer hardened by HDTV hardening are obtained. A comparison of experimental data and calculations of the theoretical model showed a good qualitative correspondence between them, demonstrate a high «sensitivity» of the method in relation to the nature of the change in hardness over the depth of the hardened layer. It is shown that the proposed approach is promising for solving the inverse problem of restoring the spatial distribution of hardness based on experimental data.

The goniometric method was approbated to determine the dependence between amplitude-angle characteristics and depth of the surface steel layers hardened by high-frequency hardening and depth of hardened gray iron specimens layer – with chill. It is shown that the optimal angle corresponding maximum of excited surface wave amplitude in steel specimens is decreasing up to 24–26'vs. hardened depth layer. But when the tested specimens from cast iron this angle decreasing is nearly of 6°. Recommendations on the use of research results in practice are given.
Dependence of the Correlation Coefficient Between the Results of a Parameter Measurement and Its True Values on the Reduced Measurement Error
Authors: Sandomirski S. G.
Published: April 2019

Magnetic testing of steels' mechanical properties is based on their correlation with steels' magnetic parameters. The purpose of this work was to establish dependence of the attainable correlation coefficient Rmax between measurement results and the parameter values a on the reduced error of its measurement. The article proposes a model of the correlation field between the parameter true values and the results of its measurement with a given reduced error δ. The merits and legitimacy of using the model for estimation of the achievable correlation coefficient Rmax are substantiated. Analysis of influence of δ parameter measurement in different ranges d of its change on Rmax is carried out. Results are compared with the previous analysis for the relative measurement error. It has been established in this work that the coefficient Rmax calculated for the reduced measurement error is always smaller than Rmax one calculated for the relative measurement error. However in the practically important range of variation of d with δ ≤ 0.05 the difference between the Rmax values calculated for the reduced and relative measurement errors is not large. This allows us to use the developed formula for the dependence Rmax = Rmax (δ, d) at Rmax ≥ 0.8 for both relative and reduced measurement errors δ. The obtained result allows us using the reduced measurement error of a metrologically certified measuring instrument to obtain the maximum attainable correlation coefficient between the true values and the results of measuring a parameter in a given range of its change without measurements. As an example, we define the conditions for the non-destructive testing of steels under which one can use measuring of magnetic parameters with the installation certified based on the reduced measurement error.
Plasmatron for Coatings
Authors: Okovity V. A. , Panteleenko F. I. , Okovity V. V. , Astashinsky V. M.
Published: April 2019

The paper analyzes reasons for application of plasma torches of special design for deposition of heat-resistant layers of thermal barrier coatings that contribute to minimum oxygen content in the zone of spraying. It contains detailed description of design for a plasma torch with a nozzle that allows better protection of a plasma stream against atmospheric exposure.

Heated inert gas (Ar) is fed inside the nozzle along its walls through holes in its end part. Air around a plasma jet is displaced, additional compression of the plasma occurs and due to this oxygen content is decreased in a coating and efficiency of material deposition is increased. An additional use of a tungsten insert in an electronic node makes it possible to create a pair of tungsten – tungsten in an electrode assembly and the life of the electrode assembly will be increased due to high erosion resistance, electrical conductivity, thermal conductivity and sufficient strength in 2–2.5 times while increasing spray performance through toughening regimes. The paper presents testing results of the developed plasma torch and its prototype for duration of continuous operation and intensity at 500 A current, 70 V voltage, nitrogen flow rate of 45 l/min (standard mode for deposition of oxide ceramics). Coatings from nickel–chromium–aluminum–yttrium powder have been obtained while using plasma torches with the same parameters of deposition and a comparative analysis of the technological properties have been made in the paper. The developed plasma torch has more qualitative characteristics of subsurface plasma coatings: increase in adhesive strength – by 1.4 times, material utilization ratio – by 1.3 times, micro-hardness – by 1.3 times, porosity decrease – by 2.3 times.
Synthesis of Optimal Dynamic Mode of Manipulator Boom Movement Mounted on Elastic Base
Authors: Loveikin V. S. , Mischuk D. A.
Published: April 2019

In order to increase reliability and accuracy of robot manipulators or other construction equipment used for lifting operations an optimum dynamic mode for moving its boom system has been calculated in the paper. Results of the research have made it possible to construct a mathematical model for manipulator movement and obtain kinematic characteristics of the optimum dynamic mode. While determining the optimum dynamic motion mode, a criterion action has been used as an optimization criterion which represents a time integral with an integrand function expressing a dynamic component of manipulator drive power. Functions for changing kinematic characteristics of an manipulator boom have been calculated when it moves from one predetermined position to another one and which correspond to optimum dynamic mode of motion. Search for an optimum motion mode has been performed by minimizing the optimization criterion using the Euler–Poisson equations. In this case a generalized angle of rotation has been used which permits to relate movement of the boom and oscillations of its support part. As a linking component differential equations of system motion have been also applied, in which relationships between an oscillation angle, rigidity of a manipulator support, and its mass-geometric characteristics have been recorded. Results of the work can be useful for refinement and improvement of existing engineering methods for calculating the drive mechanisms of manipulators both at design/construction stages and in real operation modes, and the results can also be used while making design or improvement of similar executive mechanisms for construction equipment and robots.
Some Comments on Designing of Steel Structures According to European Standards
Authors: Davydov Y. Y.
Published: April 2019

Critical comments on the European standards for designing steel structures including welded and bolted joints have been given on the basis of application experience and executed analysis. Comments are presented in comparison with similar regulatory documents which are in effect in Belarus. European standards concerning loads (determination of calculated load values and drawing up of design load combination) have been also analyzed. Particular attention has been paid to the analysis of European standard requirements to steel and welding materials and their comparison with mechanical characteristics of similar materials used for manufacture of steel structures in Belarus. The paper gives notice to the rules which are accepted in the European norms and the rules being compared with the similar rules used in Construction rules and regulations (SNiP) lead to a significant increase in material consumption of steel structures. First of all, it concerns assignment of partial load factors and classification of sections for ensuring local stability of compressed and partially compressed elements. The paper pays a special notice to the rules of Eurocodes that do not meet requirements of State standards and technical specifications operating in the Republic of Belarus. Significant limitations of some European rules regarding calculation of centrally and eccentrically compressed elements, absence of rules for testing overall stability of through and step columns which are widely used while implementing projects Belarus have been described in the paper. Conclusions have been made on the basis of the analysis results and according to them application of European standards for designing steel structures has significant limitations on the territory of the Republic of Belarus.
Heat-Resistant Foam Concrete on the Basis of Two-Component Binder
Authors: Leonovich S. N. , Sviridov D. V. , Belanovich A. L. , Savenko V. P. , Karpushenkov S. A.
Published: April 2019

The composition of dry mix on the basis of two-component cementing agent (aluminous cement and clay of the “Kustikha” field), mineral additives (a metakaolin, the RSAM sulfoaluminate modifier, waste of basalt fiber), Ufapore foamer and the accelerating and plasticizing “Citrate-T” additive is developed. When mixing “Citrate-T” additive with water at Water/Solid = 0.45–0.70, the subsequent mechanical binder and hardening of a foam mass heat-resistant foam concretes with a density of 300–650 kg/m3 are formed (depending on Water/Solid value). Foam concretes have strength on compression of 0.2–2.5 MPa before warming up when their initial strength depends on processes of hydration curing of aluminous cement that provides fixation of their porous structure. After annealing at 1000 °C foam concretes have final strength of 0.3–3.2 MPa due to processes of solid-phase agglomeration of clay with other components of dry mix at their heating. Foam concretes after annealing unlike foam concretes on the basis of a Portland cement and aluminous cement have big strength. Introduction of the accelerating and plasticizing “Citrate-T” additive into composition of the dry mix leads to an increase of rheological properties in expanded foam mass and time reduction of its drying and curing. It has been established that an essential role is played by the relation Water/Solid: at increase in the relation Water/Solid (with 0.45 to 0.70) occurs increase in volume of foam mass after a mechanical binder, and also heterogeneity of pores and their sizes increases that leads to reduction of density of foam concretes and strength on compression.
Comparative Evaluation of Results on Test of Concrete Beams with Fiberglass Rebar and Calculated Data
Authors: Begunova N. V. , Grahov V. P. , Vozmishchev V. N. , Kislyakova I. G.
Published: April 2019

The paper presents results of the study for samples of concrete beams reinforced with fiberglass rebar produced by LLC “KomAR”. The aim of the study is to determine strength, stiffness and crack resistance of beams with fiberglass rebar, various reinforcement schemes and their comparison with calculated data. Tests have been carried out in accordance with the regulatory requirements for a design scheme with two points of load application P1 = P2. The adopted scheme of pure bending is used in the laboratory for informativeness of the obtained results and getting maximum efforts in a stretched zone of bent elements. A comparison has been made of the data obtained as a result of tests with the ones which have been calculated according to the document SP (Construction Rules) 295.1325800.2017 “Concrete structures reinforced with polymer composite reinforcement. Design rules”, this document is based on the design principle of concrete structures reinforced with metal reinforcement. Due to the fact that composite fittings significantly differ from metal fittings in a number of indicators, comparative tests of concrete beams reinforced with metal and composite fittings have been carried out earlier. Data of the investigations are necessary for understanding behavior of structures and possibility of their application in the objects of capital construction. An excess of inclined section strength on the action of transverse forces over an actual one has been revealed when calculating concrete beams according to the I group of limiting states. While making calculations for the II group of limiting states, the need has been revealed to make changes in the procedure for calculating width of crack opening in order to approximate the calculated data to the data obtained as a result of tests and a procedure for calculating deflections.
Analysis of Implementation Effectiveness of Two Working Fluids Characterized by Different Viscoelastic Characteristics at Hydrodynamic Impact on the Borehole Bottom Zone
Authors: Kupavykh K. S. , Kupavykh A. S. , Morenov V. A.
Published: April 2019

Combination of hydrodynamic impact on the formation with acid treatment may be seen as a promising direction in the field of well development and repair in complex geological conditions. With multiple repetition of hydraulic shocks in conjunction with the injection of acid solution, the depth and opening of cracks gradually increases, which contributes to a deeper penetration of the acid solution into the reservoir. The article presents analytical studies, which are aimed at determining the effectiveness of applying the technology of hydrodynamic impact on the bottomhole zone of an oil reservoir when using two fluids with different viscoelastic characteristics as a working fluid. They are devoted to determining the pressure drop at the borehole bottom depending on the initial applied pressure at the wellhead, the velocity of the shock wave, the viscosity of the working and well fluid, and their quantity. These studies were based on the well-known models of Thomson – Tаt and Maxwell, considering viscous liquid flow. The dependence obtained proves that with an increase in the pressure pulse generated at the wellhead, the development of pressure pulses at the borehole bottom is a power-law dependence, and with significant volumes of fluid in contact with the bottomhole formation zone, the pressure drop generated at the borehole bottom does not depend only on pressure pulses generated at the wellhead, but also on the dynamic viscosity of this fluid. Conducted studies have shown the effectiveness of hydrodynamic impact technology application when using two liquids with different viscoelastic characteristics and obtaining a synergistic effect during the development and repair of wells in low-permeable reservoirs. Analytical studies were based on data from previously conducted experimental industrial tests on the operating injection well.
Modeling of Asphalt Concrete While Using Discrete Element Method
Authors: Alekseenko V. V. , Vabishchevich K. Yu. , Verkhoturova E. V.
Published: April 2019

The paper considers a mathematical model which is used to study a composite material similar in structure to asphalt concrete and it takes into account presence of solid particles of different sizes and a soft and plastic binder. The twodimensional method of discrete elements has been applied to investigate destruction of asphalt-concrete samples under uniaxial compression, tension during splitting and compression by the Marshall method. The numerical model takes into account presence of large particles of rubble, asphalt mastic filling rubble pores and sticky (capable of recovering after rupture) communication between rubble particles. The force interaction between various components of the asphalt concrete has been described with the help of elastic repulsion between rubble particles, friction force and force responsible for sticking of particles due to presence of a binder. This model gives a correct fracture pattern for uniaxial compression, stretching during splitting and compression according to the Marshall method and this pattern coincides with the real experiment. It is the correct picture of destruction for three different schemes of material loading which makes it possible to assess the adequacy of the mathematical model which has been used. Basic physico mechanical characteristics of the binder which determine strength and deformability of asphalt concrete have been established in the paper. It has been shown that for an adequate description of physico mechanical characteristics for asphalt concrete it is necessary to study and measure properties of an asphalt binder that is a mixture of bitumen and fine mineral filler which determines parameters of interaction between rubble particles. The numerical experiments serve as a basis and make it possible to propose new laboratory methods for testing a mixture of stone materials and organic binders which are much simpler and, therefore, cheaper than standard tests on asphalt concrete. In addition these tests will more accurately predict behavior of asphalt concrete in real conditions.
Crossroad control algorithm based on V2I-interaction
Authors: Klimovich A. N. , Shuts V. N.
Published: April 2019

The importance of efficient traffic management problem grows every year. Constantly increasing number of vehicles and traffic volume requires improvement of methods and algorithms of traffic control. Such improvement becomes possible due to the spreading of global navigation and positioning systems, the development of wireless communication technologies and mobile internet, the advance in specialized technologies for interaction between vehicles and road infrastructure (V2I), the enhancement of machine learning models, computer vision algorithms, the emergence of driverless cars. This paper considers the novel approach to traffic management at intersection based on the use of V2I communication, describes general scheme of such approach and differences with conventional traffic light regulation. Developed algorithm of intersection management utilizes advantages of V2I communication to increase throughput of the intersection comparing to simple traffic light regulation and more advanced adaptive methods. The increase of throughput is achieved due to the dynamic construction of regulation phases which can be done because of more complete information about traffic flow. The comparence of various methods of regulation was performed in developed traffic simulation environment based on multi-agent approach.
Transdisciplinary models of hydraulic drives of mobile machinery
Authors: Puzanov A. V.
Published: April 2019

Modern drive engineering requires a comprehensive analysis of all work processes in hydraulic drives, solving the problems of modeling the technological processes of their production using mathematical and software tools of various physicality.

The article proposes an approach to the development of hydrodrives of mobile equipment based on transdisciplinary models of instruments and control systems. These models are designed to unite in a single information space a methodical and mathematical apparatus of various physicality: mechanics, kinematic, hydromechanics, heat engineering, and methods for their solution. These measures will increase their adequacy, reduce assumptions and reduce the safety factor as a measure of imperfection of the scientific and technical understanding of the facility.

The article gives an example of the use of this approach in the development of volumetric hydraulic drives of mobile equipment a technique for calculating the indicator diagram of an axial-plunger hydraulic machine at a micro level using the Matlab / Simulink, Autodesk Simulation CFD and Autodesk Simulation Mechanical software complexes. The indicator diagram of the hydraulic machine is a clear characteristic of the dynamic qualities of the product. From the correctness of the calculation of this characteristic, the dynamic properties, reliability and resource of the drive as a whole depend.
Linguistic database and software for english-belarusian-russian dictionary of technical terms
Authors: Makarych M. V. , Popova Y. B. , Shved M. O.
Published: April 2019

The central object of computer lexicography is a computer or electronic dictionary, which must have a sufficiently large vocabulary, provide the consistent extraction of information depending on the user’s need and provide complete grammatical information about the words of input and output languages. Taking into account the current trend in the development of special terminological dictionaries, the authors propose an English-Belarusian-Russian dictionary of technical terms. At the initial stage of the work the dictionary was named TechLex and covers the following subject areas: architecture and construction, water supply, information technology, pedagogy, transport communications, economics, energy-supply. Currently, each subject area of the dictionary is located in the Internet GoogleTable and contains about 1000 terms. It has the possibility to be simultaneously filled by several teachers. The linguistic database of the dictionary is not created by the traditional way of processing a large number of paper dictionaries and combining the received translations. Lexis from sequential processing of scientific and technical English periodicals of particular subject areas is the base of it. The software of the proposed electronic dictionary is designed taking into account the analysis of modern electronic multilingual translation dictionaries and is a client-server application in Java programming language. The client part of the system contains a mobile application for the Android operating system, which was tested on tablets and smartphones with different screen diagonals. The interface of TechLex dictionary is designed in such a way that only a single zone is activated according to the query, so there is no need to view all the subject areas of the dictionary. The proposed TechLex dictionary is the first technical multilingual electronic dictionary with an English-Belarusian-Russian version.
Antecedentes da inovação na gestão pública: análise de experiências inovadoras do setor rural brasileiro
Authors: Santos Luana Ferreira dos , Sano Hironobu , Sousa Washington José de
Published: April 2019

Este estudo analisa experiências de inovações no setor público brasileiro, no meio rural, premiadas nas 20 edições do “Concurso Inovação no Setor Público” promovido pela Escola Nacional de Administração Pública. Concomitantemente, analisa antecedentes, barreiras e indutores inerentes a tais inovações. O referencial teórico foi desenvolvido à luz do modelo de antecedentes da inovação no setor público. A pesquisa se caracteriza como qualitativa-descritiva, com a utilização de análises documental e temática. Os resultados da análise de 16 casos inovadores do setor rural revelam maior número de indutores como antecedentes organizacionais e de barreiras como antecedentes ambientais. As ações desenvolvidas nas experiências para solucionar/minimizar as barreiras são indicadores de participação social, revelando que há, no quesito participação, um importante aspecto dos casos rurais premiados. Como agenda para pesquisas futuras, tornam-se relevantes estudos comparando experiências premiadas e experiências não premiadas quanto às características que explicam como dada iniciativa se torna caso de sucesso.
On Temperature-Falloff Interpretation in the Circulation Phase of the Steam-Assisted-Gravity-Drainage Process
Authors: Irani Mazda , Ghannadi Sahar
Published: April 2019

Steam-assisted gravity drainage (SAGD) is the preferred method to extract bitumen from Athabasca oil-sand reservoirs in western Canada. Bitumen at reservoir conditions is immobile because of high viscosity, and its saturation is typically large, which limits the injectivity of steam at in-situ conditions. In current industry practice, steam is circulated within injection and production wells. In theory, wells should be converted to SAGD production mode after a period when bitumen is mobile and communication is established between the injector and the producer. Operators use temperature-falloff data to predict successful conversion time. But temperature-falloff data are evaluated qualitatively, and there is not an analytical/numerical framework in which one can use such data. Although the bitumen heating sounds simple, approach wells are failing after steam injection because of steam breakthrough or sand production. Most of these wells are periodically returned to circulation/bullheading to ramp up production rates and heal the hot spots. Most of such failures are associated with early conversion to full SAGD, which shows the need to formulate an analytical/numerical framework to predict the right timing for conversion to full SAGD. In this presentation, the time of flight (ToF) is effectively used to convert spatial variations of temperature into time response of temperature variation at the well sandface. ToF defines the time an oil droplet needs to travel through a medium—more specifically, from its current location to the well sandface. By solving the heat transfer and Darcy's law simultaneously, the ToF is converted to a relationship of the temperature vs. time profile at the producer. This approach has been applied to SAGD well pairs with different geology, and the temperature-falloff trends are presented.
A Semianalytic Solution for Temporal Pressure and Production Rate in a Shale Reservoir With Nonuniform Distribution of Induced Fractures
Authors: Sheng Guanglong , Javadpour Farzam , Su Yuliang , Liu Jinghua , Li Kunjie , Wang Wendong
Published: April 2019

The network of induced fractures and their properties control pressure propagation and fluid flow in hydraulically fractured shale reservoirs. We present a novel fully fractal model in which both the spacing and the porosity/permeability of induced fractures are distributed according to fractal dimensions (i.e., fractal decay of fracture density and the associated porosity/permeability away from the main induced fracture). The fractal fracture distribution is general, and handles exponential, linear, power, and uniform distributions. We also developed a new fully fractal diffusivity equation (FDE) using the fractal distribution of fractures and their properties. We then used, for the first time, the semianalytic Bessel spline scheme to solve the developed diffusivity equation. Our proposed model is general and can capture any form of induced-fracture distribution for better analysis of pressure response and production rates at transient- and pseudosteady-state conditions. We compared the unsteady-state and pseudosteady-state pressure responses calculated by our fully fractal model with former models of limited cases: uniform fracture spacing and uniform porosity/permeability [conventional diffusivity equation (CDE)]; variable fracture spacing and uniform porosity/permeability [modified CDE (MCDE)]; and uniform fracture spacing and fractal porosity/permeability distribution (FPPD). We used these models to match and predict the production data of a multifractured horizontal gas well in the Barnett Shale. Our results showed that the fractal distribution of fracture networks and their associated properties better matches the field data. Uniform distribution of induced-fracture networks underestimates production rate, especially at early time.
Intra-operative red blood cell transfusion and mortality after cardiac surgery
Authors: Vlot Eline A , Verwijmeren Lisa , de Garde Ewoudt M.W. Van , Kloppenburg Geoffrey T.L. , Dongen Eric P.A. Van , Noordzij Peter G.
Published: April 2019

Background

Anemia in cardiac surgery patients has been associated with poor outcomes. Transfusion of red blood cells during surgery is common practice for perioperative anemia, but may come with risks. Little is known about the association between intra-operative transfusion and mortality in patients undergoing cardiac surgery.

Methods

Single centre historical cohort study in 2933 adult patients undergoing coronary surgery with or without aortic valve replacement from June 2011 until September 2014. To estimate the odds ratio for mortality in patients receiving intra-operative transfusion, a propensity score based logistic regression analysis was performed.

Results

Intra-operative transfusion was associated with a more than three-fold increased risk of 30-day mortality. Patients in the highest quartile of probability of transfusion were older (age 75 vs 66; P<0.001), had a higher EuroSCORE (6 vs 3; P<0.001), had lower preoperative hemoglobin levels (7.6 vs 8.9 mmol/l; P<0.001), had combined surgery more often (CABG + AVR in 33.4% of cases vs 6.6% (P<0.001) and a longer duration of surgery (224 vs 188 minutes; P<0.001). The association between intra-operative transfusion and mortality persisted after adjustment for these risk factors (adjusted OR 2.6; P=0.007).

Conclusions

Intra-operative transfusion of red blood cells was found to be associated with increased mortality in adults undergoing coronary surgery. Preoperative patient optimization may improve perioperative outcomes by reducing the likelihood of requiring transfusion and thus its associated risk.
Effects of intravenous infusion of lidocaine and dexmedetomidine on inhibiting cough during the tracheal extubation period after thyroid surgery
Authors: Hu Shenghong , Li Yuanhai , Wang Shengbin , Xu Siqi , Ju Xia , Ma Li
Published: April 2019

Background：Intravenous lidocaine and dexmedetomidine treatments have been proposed as methods for inhibiting cough. We compared the efficacy of intravenous lidocaine and dexmedetomidine treatments on inhibiting cough during the tracheal extubation period after thyroid surgery. Methods：One hundred eighty patients undergoing thyroid surgeries were randomly allocated to the LIDO group (received lidocaine 1.5 mg/kg loading, 1.5 mg/kg/h infusion), the DEX group (received dexmedetomidine 0.5 µg/kg loading, 0.4 µg/kg/h infusion) and the CON group (received saline), with 60 cases in each group. The primary outcomes of cough were recorded. Secondary outcomes included hemodynamic variables, awareness time, volume of drainage, the postoperative visual analogue scale and adverse effects were recorded. Results: The incidence of cough were significantly lower in the LIDO group (28.3%) and the DEX group (31.7%) than that in the CON group (66.7%) (P=0.000). Additionally, both moderate and severe cough were significantly lower in the LIDO group (13.3%) and the DEX group (13.4%) than these in the CON group (43.4%) (P<0.05). Compared with the two treatment groups, both mean arterial blood pressure and heart rate were significantly increased in the CON group during tracheal extubation (P<0.05). Compared with the CON group, the volume of drainage was significantly reduced in the two treatment groups within 48 hours after surgery (P<0.05). compared with the CON group, the postoperative visual analogue scale was significantly lower in groups LIDO and DEX after surgery(P<0.05). Compared with the LIDO group and the CON group, the time to awareness was longer in the DEX group (P<0.05). In the DEX group, bradycardia was noted in 35 patients, while no bradycardia was noted in LIDO group and CON group. Conclusion: Compared with intravenous infusions of normal saline, both lidocaine and dexmedetomidine had equal effectiveness in attenuating cough and hemodynamic changes during the tracheal extubation period after thyroid surgery, and both of these treatments were able to reduce the volume of postoperative bleeding and provide better analgesic effect after surgery. But intravenous infusions of dexmedetomidine resulted in bradycardia and delayed time to awareness when compared with lidocaine and normal saline.
Informative Supraglottic Airway versus Endotracheal Tube During Interventional Pulmonary Procedures – A Retrospective Study
Authors: Behrens Kyle M , Galgon Richard E
Published: April 2019

Background: As the field of interventional pulmonology (IP) expands, anesthesia services are increasingly being utilized when complex procedures of longer duration are performed on sicker patients with high risk co-morbidities and lung pathology. Yet, evidence on the optimal anesthetic management for these patients remains lacking. Our aim was to characterize the airway management and, secondarily anesthetic maintenance patterns used for IP procedures at our institution.

Methods: From 2894 identified encounters, charts of 783 patients undergoing an IP procedure with general anesthesia over a 5-year period, employing an endotracheal tube (ETT) or a supraglottic airway (SGA) for airway maintenance, were identified and reviewed after exclusions. Patients posted for a concurrent thoracic surgical procedure and those already intubated at presentation were excluded. Baseline patient demographics, procedure, proceduralist type, anesthesia maintenance modality, neuromuscular blocking drug (NMBD) use, and airway management characteristics were extracted and analyzed.

Results: Inhaled general anesthesia with an ETT for airway maintenance was most commonly employed; however, SGAs were used in one-third of patients with a very low conversion rate (0.4%), and their use was associated with a significant reduction in NMBD use.

Conclusions: In this large series of patients receiving general anesthesia for IP procedures, inhaled anesthetic agents and ETTs were favored. However, in appropriately selected patients, SGA use was effective for airway maintenance and allowed for a reduction in NMBD use, which may have implications in this patient population who may have an increased risk for pulmonary complications and warrants further investigation.
Prognostic value of endothelial biomarker in refractory cardiogenic shock with ECLS: a prospective monocentric study
Authors: Tsai Tsung-Yu , Tu Kun-Hua , Tsai Feng-Chun , Nan Yu-Yun , Fan Pei-Chun , Chang Chih-Hsiang , Tian Ya-Chung , Fang Ji-Tseng , Yang Chih-Wei , Chen Yung-Chang
Published: April 2019

Background

Extracorporeal membrane oxygenation (ECMO) is often used in critical patients with severe myocardial failure. However, patients on ECMO often have high mortality rate. Recent studies suggest that endothelial activation with subsequent vascular barrier breakdown is a critical pathogenic mechanism in organ damage and related to the outcome in critical illness. This study aimed to determine whether the endothelial biomarkers could serve as prognostic factors for the outcome of patients on ECMO.

Methods

This prospective study enrolled total 23 critically ill patients on veno-arterial ECMO in the intensive care units of a tertiary care hospital between March 2014 and February 2015. Serum samples were tested for thrombomodulin, angiopoietin (Ang)-1, Ang-2, and vascular endothelial growth factor (VEGF). Demographic, clinical, and laboratory data were also collected.

Results

The overall mortality rate was 56.5%. The combination of Ang-2 at the time of ECMO support (day 0) and VEGF at day 2 had the ability of discriminating mortality (area under receiver operating characteristic curve [AUROC], 0.854; 95% confidence interval: 0.645-0.965).

Conclusions

In this study, we found that the combination of Ang-2 at day 0 and VEGF at day 2 was a modest model for mortality discrimination in this group of patients.
Patterns of Uveitis in Children According to Age: Comparison of Visual Outcomes and Complications in a Tertiary Center
Authors: Al-Haddad Christiane , BouGhannam Alaa , Fattah Maamoun Abdul , Tamim Hani , Moussawi Zeinab Ali El , Hammam Rola
Published: April 2019

Background: Uveitis in the pediatric population is uncommon, accounting for 2 to 14% of all uveitis cases, yet resulting in significant ocular morbidity. A number of studies have focused on patterns and complications of uveitis in the pediatric age group (≤ 16 years). In this report, we studied children with uveitis syndromes focusing on demographics, anatomic distribution, etiologies, treatment, and complications. We additionally divided subjects into two age groups to look into any differential characteristics pertaining to the younger age group and the role of amblyopia as a cause of visual loss. Methods: Retrospective chart review of 80 eyes of 49 uveitis patients aged ≤16years. Subjects were categorized by age of onset into visually immature (≤8 years) and visually mature group (>8 years). Data compared between the two age groups included demographics, disease characteristics, visual outcomes and complications. Results: Idiopathic uveitis was the most common diagnosis (51%). Anterior uveitis complications (posterior synechiae and band keratopathy) were more common in the younger group (p=0.002 and p=0.03 respectively) while posterior uveitis manifestations (vitreous haze and vasculitis) were more common in the older age group (p=0.04 and p<0.001 respectively). Amblyopia was the most common cause of vision loss in the visually immature versus cataract in the visually mature. Conclusion: Anterior uveitis and its complications were more common in visually immature group in our cohort. Amblyopia was identified as the main cause of visual loss in the younger population.
Association between High Cumulative Numbers of Elevated Heart Rate and Mortality in Neurological ICU patients: Retrospective Analysis of eICU Collaborative Research Database
Authors: Zhou Dawei , Li Zhimin , Zhang Shaolan , Zhou Jianxin , Shi Guangzhi
Published: April 2019

Background

Heart rate is routinely measured in Neurological intensive care unit(NICU), but its prognostic value remains debated. We sought to evaluate the association of high cumulative numbers of elevated Heart Rate (HcneHR) with mortality in NICU patients.

Methods

We used a large observational eICU Collaborative Research Database (eICU-CRD), where continous heart rate monitoring every 5 minute was available. We collected periodic heart rate, disease severity (APACHE IV score), NICU and hospital mortality and other information in 8347 patient admissions from the eICU-CRD. The cumulative numbers of Heart Rate (cneHR) were defined as >100 beats/min in first admittion 24 hours, and if cneHR ≥10,then was defined as higt cneHR(HcneHR). The primary outcome was NICU mortality. The other outcomes were hospital mortality, length of NICU stay and APACHE IV score. Multivariable logistic regression was used to assess for association for HcneHR and other covariance with NICU and hospiltal discharge status.

Results

The mean age of patients were 63 years, and the most frequent disease categories of NICU in eICU-CRD were postoperation (25%), stroke(19%), traumatic brain injury(14%). The mean APACHE IV score was 50. Overall NICU mortality of the cohort at discharge was 4%, and hospital mortality was 8%. The NICU mortality of HcneHR patients was 7%. Adjusted logistic regression for HcneHR showed a significantly increased risk of NICU death with odds ratio 1.61(confidence interval, 1.26-2.06; P <0 .001).

Conclusions

In adult neurocritically ill patients, we found a significant association for HcneHR with elevated mortality and several others important patient-centered outcomes.
Interpreting HIV Diagnostic Histories into Infection Time Estimates: Analytical Framework and Online Tool
Authors: Grebe Eduard , Facente Shelley N. , Bingham Jeremy , Pilcher Christopher D. , Powrie Andrew , Gerber Jarryd , Priede Gareth , Chibawara Trust , Busch Michael P. , Murphy Gary , Kassanjee Reshma , Welte Alex
Published: April 2019

Background

It is frequently of epidemiological and/or clinical interest to estimate the date of HIV infection or time-since-infection of individuals. Yet, for over 15 years, the only widely-referenced infection dating algorithm that utilises diagnostic testing data to estimate time-since-infection has been the ‘Fiebig staging’ system. This defines a number of stages of early HIV infection through various standard combinations of contemporaneous discordant diagnostic results, using tests of different sensitivity.

Objective

To develop a new, more nuanced infection dating algorithm, we generalised the Fiebig approach to accommodate positive and negative diagnostic results generated on the same or different dates, and arbitrary current or future tests – as long as the test sensitivity is known. For this purpose, test sensitivity is conceptualised as the probability that a specimen will produce a positive result, expressed as a function of time since infection. This can be summarised as a median ‘diagnostic delay’ parameter, together with a measure of inter-subject variability.

Methods

The present work outlines the analytical framework for infection date estimation using subject-level diagnostic testing histories, and data on test sensitivity. We introduce a publicly-available online HIV infection dating tool that implements this estimation method, bringing together 1) curatorship of HIV test performance data, and 2) infection date estimation functionality, to calculate plausible intervals within which infection likely became detectable for each individual. The midpoints of these intervals are interpreted as infection time ‘point estimates’ and referred to as Estimated Dates of Detectable Infection (EDDIs).

Results

In many settings, including most research studies, detailed diagnostic testing data are routinely recorded, and can provide reasonably precise estimates of the timing of HIV infection. We present a simple logic to the interpretation of ‘diagnostic testing histories’ into ‘infection time estimates’, either as a point estimate (EDDI) or an interval (earliest plausible to latest plausible dates of detectable infection), along with a publicly-accessible online tool that supports wide application of this logic.

Conclusions

This tool, available at https://tools.incidence-estimation.org/idt/, is readily updatable as test technology evolves, given the simple architecture of the system and its nature as an open source project.
Perioperative Goal-Directed Hemodynamic Therapy: From Invasive Monitoring To Automated Physiological Closed-Loop Systems
Authors: Coeckelenbergh Sean , Zaouter Cedrick , Alexander Brenton , Rinehart Joseph , Duranteau Jacques , Linden Philippe Van der , Joosten Alexandre
Published: April 2019

Perioperative goal-directed hemodynamic therapy (GDHT) has evolved from invasive “supra-physiological” maximization of oxygen delivery into minimally and non-invasively guided automated stroke volume optimization. Throughout this evolution, investigators have simultaneously developed novel monitors, updated strategies, and automated technologies to aid them in GDHT implementation. In particular, closed-loop systems have been created to both increase GDHT compliance and decrease physician workload. Currently, these automated systems offer an elegant approach to help the clinician optimize cardiac output and end-organ perfusion during the perioperative period. Most notably, automated fluid optimization guided by dynamic parameters of fluid responsiveness has shown its feasibility, safety, and impact. Making the leap into fully automated GDHT has been accomplished on a small scale, but there are considerable challenges that must be surpassed before integrating all hemodynamic components into an automated system during general anesthesia. In this review we will discuss the potential future of automated GDHT by covering the key events that paved the way from initially complex and time consuming approaches to simple yet effective hands-free strategies.