bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity of Cascade Pressure Distribution for Inverse Design of Turbine Blade
Authors: Nanthini R. , Prasad B. V. S. S. S. , Sanyasiraju Y. V. S. S.
Published: January 2020

In an iterative inverse design of a turbine blade, choice of initial guess profile is crucial. As the pressure distribution is very sensitive to the leading and trailing edge shapes and the profile slope and curvature, a good initial guess profile will help in faster convergence. In this paper, the sensitivity of the pressure distribution is determined by carrying out numerical simulations with ANSYS Fluent 17.2 for the inviscid flow. The flow domain comprises of a two dimensional transonic turbine cascade. It consists of a turbine blade enclosed by inlet, outlet and periodic boundaries. Inlet total pressure, total temperature and inlet angle are given as the boundary conditions at the inlet and static pressure is imposed at the outlet boundary. The flow is solved for continuity, momentum and energy equations. Sensitivity of different parameters — leading edge thickness, trailing edge thickness, leading edge shape, inlet and outlet wedge angle on the pressure distribution is demonstrated for VKI blade cascade. It is found that the pressure side of the profile is less sensitive and that even a small variation in suction side of the profile geometry can affect the performance of the blade significantly. It is shown that, with the proposed methodology and sequence of steps, the final guess blade is quite close to the original blade.
Analysis of Aerostatic Thrust Bearing for S-CO2 Turbomachinery
Authors: Patel Ashutosh , K. Balasubramanian Aanand , Biradar Vijay , Srivatsa Shreyas , Kumar Pramod , Sonti Venkata R.
Published: January 2020

Preliminary analysis for the S-CO2 Brayton power cycle development suggests small size and high operating speed of turbomachinery. The axial thrust due to the pressure differential generated in the turbomachinery is transferred to the bearing through the shaft. Angular contact ceramic bearings used for high speed operations are incapable of withstanding high axial loads.

The current paper presents, theoretical and computational analysis of a 4-hole aerostatic thrust bearing for S-CO2 turbomachinery applications. CFD analysis is performed for different axial clearance gap between stationary and rotating discs of the thrust bearing. The computations have been performed for two different fluids — air and CO2. This computational domain of the flow regime splits into two regions: adiabatic flow through the orifice and isothermal flow in the clearance volume comprising the clearance gap. The influence of the following parameters such as, pressure distribution across thrust pad area, mass flow rate, load capacity and the local velocity in the gap on the stiffness of the bearing are investigated.
Finite Element Model Based Full Spectrum Response Analysis of a Cracked Rotor With Internal and External Damping
Authors: Roy Dipendra Kumar , Tiwari Rajiv
Published: January 2020

The ratio of internal and external damping is one of the important fault parameters and it leads to instability of a rotor shaft at higher spin speeds. The crack in a rotor is one of the sources of its instability due to the crack internal damping. A rotor with crack internal damping that originates from the rubbing action between the two crack faces. For a sustained stable operation of the rotor, it is imperative to analyze rotor parameters such as the internal and external damping and other parameters, like the additive crack stiffness and disc eccentricity. Therefore, the present work considers a full spectrum response analysis of a transverse cracked shaft based on the finite element method. The rotary and translations of inertia are considered including of gyroscopic effect in the rotor system. The transverse crack is modeled based on the switching crack assumption. The crack in the rotor gives forcing with multiple harmonics with the forward and backward. The equation of motion has been developed for the rotor system having four degrees of freedom at each node and using MATLAB™ Simulink the responses are generated for a numerical example.
Fluid Thermal Network Studies on Cooled Nozzle Guide Vane
Authors: Kukutla Pol Reddy , Prasad B. V. S. S. S.
Published: January 2020

The aerothermal analysis is reported with the help of one-dimensional network modeling for the impingement cum film cooled gas turbine vane. The purpose of this one-dimensional simulation is to obtain the optimized film hole diameters of each row by analyzing the coolant flow distribution and overall effectiveness variations. FlownexR2017 commercial code is used to determine the detailed steady-state performance of the cooling vane. The results show that it is a useful simulation tool to obtain improved effectiveness of film cooling rows in a relatively short turn around time.
Performance Enhancement of a Hydraulic Savonius Turbine by Optimizing Overlap and Gap Ratios
Authors: Kerikous Emeel , Thévenin Dominique
Published: January 2020

Due to the significant increase in the human population, satisfying its energy demand becomes a major challenge at present and in the future. Hydropower is a form of renewable energy that converts the potential or kinetic energy of water to useful mechanical power. Considering the low speed of streaming water, hydraulic Savonius turbines can be effectively used for such conditions. Such turbines are robust and very simple to manufacture. However, Savonius turbines suffer from a poor efficiency. For this purpose, an optimization process was done to improve the power density of a hydraulic Savonius turbine while keeping its simple structure. Here in this study, the two main geometry parameters, i.e., 1) the overlap ratio, 2) the gap ratio, are served. Furthermore, the optimal operating range for both parameters is presented. To achieve this goal, many different geometries of the turbine are simulated by using the computational fluid dynamics (CFD) code Star-CCM+. In the optimization process, all simulations are driven by the in-house software OPAL++. The output power coefficient (Cp) is considered as a single target function to be maximized. The performance of the optimal geometry is compared with the standard design over the whole range of operation, leading to an improvement in the performance of the turbine by about 8%.
Simulation of Pollutant Emissions in a Small-Sized Combustion Chamber With a Gas Fuel for Various Regime Modes
Authors: Gurakov Nikita I. , Zubrilin Ivan A. , Chechet Ivan V. , Anisimov Vladislav M. , Matveev Sergey S. , Idrisov Dmitry V. , Anisimov Michail Y.
Published: January 2020

The study shows the results of the emission simulation in a small-sized combustion chamber. The influence of temperature and equivalence ratio on CO and CxHy in the combustion chamber was investigated. Experiments and calculations were carried out for the following modes: temperature at the inlet of the combustion chamber Tinlet = 323 ... 523 K; equivalence ratio φ = 0.2 ... 0.33; normalized flow rate at the inlet of the combustion chamber λ = 0.1 ... 0.3. The simulation of combustion of natural gas was carried out.

The studies were conducted using CFD software and experimental methods. Measurements of the combustion products composition were carried out by the method of sampling collection and subsequent chromatographic analysis. The flow and combustion processes were simulated in a three-dimensional steady formulation using the Reynolds-averaged Novier-Stokes equations (RANS) and in a transient formulation using the Large Eddy Simulation (LES) method. The combustion processes were simulated by Flamelet Generated Manifold model in conjunction with the probability density function method (PDF). In addition to the above methods, the method of the reactor network model (RNM) was used to simulate the emission. As a result, a comparison of the calculated and experimental data of concentrations values of combustion products and emissions indices averaged over the combustion chamber outlet was conducted. According to the results of the calculated-experimental study obtained: - the simulated concentrations values of the main combustion products such as CO2 and H2O qualitatively and quantitatively coincide with the experimental data (the discrepancy is less than 5%) for all three approaches — RANS, LES, RNM; - when modeling CO emissions, the discrepancy between the calculated emission indices obtained by the RANS and LES methods is greatly underestimated relative to the experimental data, whereas the values calculated by the RNM method deviate from the experiment by less than 10%; - mass concentration values of unburned hydrocarbons obtained by the RANS method are overestimated relative to the experimental values, while using the LES with RNM methods, the discrepancy does not exceed 10%.
A Comparative Study of Scroll Expander Performance Using CO2 and Zeotropic Mixtures As Working Fluids
Authors: Narasimhan Arun Kumar , Guillen Perez Diego , Goswami D. Yogi
Published: January 2020

Scroll expanders are generally used for low temperature power generation applications due to their inherently small built-in volume ratio. The working fluid and operating conditions play an important role in the expander performance as well as its physical size and volume ratio. Hence, a comparative study of scroll expander performance was carried out between two different working fluids, R433C and supercritical (s-CO2). The s-CO2 Brayton cycle achieved a maximum cycle efficiency of 13.6% at an expander supply pressure of 11 MPa. Two separate scroll geometries were modeled for supercritical Organic Rankine Cycle (SORC) using R433C and s-CO2 Brayton cycle for the operating conditions that provided the maximum cycle performance. The s-CO2 scroll geometry achieved a maximum expander efficiency of 80% with a volume ratio of 2.5 and a diameter of 19 cm. The high inlet temperatures required a much higher volume ratio of 6.2 and scroll diameter of 30 cm for the R433C based SORC leading to greater leakages and lower expander efficiency of 62%. The comparative study shows that s-CO2 is better suited for scroll expander than R433C at such high expander supply temperatures.
Experimental Investigation of Droplet Velocity Fields From Elliptic Injectors in Subsonic Cross Flow
Authors: Uzair Alvi Ather , Thakur Amit , Jangam Srinivas , Kumar P. Pratheesh , Iyengar Venkat S.
Published: January 2020

The flow field associated with a liquid jet injected transversely into a crossflow, also referred as transverse jet has numerous applications in industrial, environmental and natural systems. Examples of these applications include air-breathing engines (gas turbine afterburners, ramjet and scramjet combustors), rocket engines, environmental control systems and natural flows. Earliest research of a jet in a crossflow has been motivated by applications related to environmental problems such as plume dispersal from exhaust or pipe stacks or liquid effluent dispersal in streams. This method of liquid fuel/air mixture preparation enhances flame stabilization, fuel conversion efficiency, and reduction in emissions. In gas turbine applications because of the very limited residence time available for effective fuel air mixing, detailed investigations into spray characteristics of different injector configurations in a crossflow environment is desirable for identifying promising configurations with measurements in the near field to acquire reliable spray data for development of CFD models. The velocity field of a liquid jet in the near field ejecting out from an elliptic injector into a crossflow of air were investigated experimentally at conditions relevant to gas turbine applications. A rig was set up to investigate the injection of liquid jet in subsonic cross flow with a rectangular test section of cross section measuring 100 mm by 140 mm. Experiments were done with a two injector configurations a circular 0.8mm diameter plain orifice injector and a elliptic injector with an equivalent effective area of 0.7 mm (minor axis) by 0.95 mm (major axis) which was flush mounted on the bottom plate of test section. PIV technique was used to measure droplet velocity field and distributions in the near field of the spray. Measurements were performed at a distance of 5 mm from the bottom wall in the span wise plane and the results were compared with a circular injector. It was seen that no significant differences were observed in the u and v velocity components for the elliptic and circular injectors where the geometry changes are small suggesting that parameters like velocity are not significantly affected by small changes in injector exit geometry. Further for elliptic jets it was observed that increasing the crossflow velocity and maintaining the same liquid flow rate lead to an increase in the lateral spread of the spray with no significant change in the mean vorticity values.
Dynamic Analysis of End Conditions for Shell Side Pipings of STHE
Authors: Pagar Nitin D. , Gawande S. H.
Published: January 2020

Shell and tube heat exchangers [STHE] play a very vital role in energy conversion systems, process industries like chemical, pharmaceutical, refineries etc. and in different power plants. For designing shell and tube heat exchangers, the tubes vibrational response (internally) to any random excitations of fluid flow need to be understandable. Also, circumferential inlet pipe or tube at the entrance region of the shell side, generally subject to the fluid thrust in the bends of typical pipe arrangements. It produces loadings forces and moments, leading to unavoidable vibrations. The goal of vibration analysis is to ensure that fatigue damage or fretting wear does not occur, as well as, predicted frequencies, amplitudes shall be within acceptable limits criteria. This paper reports the vibration analysis of different piping arrangement of different end conditions to understand its effects on frequencies and modes so that a designer must mitigate it, at the initial stage. Axial, lateral and torsional vibrations are analyzed for different end conditions. The boundary conditions used are both ends fixed, one end fixed and other end free, both ends free and one end fixed-other end attached to a weight. Analytical procedure is carried out to determine the frequencies for axial, lateral and torsional cases. FEA analysis and experiment using an FFT analyzer is carried out to check the convergence of the results. Very useful results are established which generates the philosophy to protect the pipings from the resonant frequencies subjected to different end conditions.
Feasibility of an Offshore Wind Farm in the North Sea Region
Authors: Pichitkul Auraluck , Sankar Lakshmi N. , Jagoda Jechiel
Published: January 2020

Preliminary design and feasibility investigation of a 2-MW wind turbine for offshore wind farm operation are presented in this study. A region in the North Sea, to the west of the West Frisian Islands offshore of Dutch coast is selected as a potential wind farm site due to its high availability of wind resources. Based on the wind data of the selected site and operating requirements of the wind farm, preliminary sizing and conceptual design of wind turbine rotor blades are carried out. Performance of the rotor design is first assessed by classical blade element-momentum theory, followed by state-of-the-art commercial CFD software. Economics and feasibility analysis of this wind turbine operating in an offshore wind farm setting is conducted using DOE/NREL scaling cost model. The feasibility investigation results reveal that the cost of energy (COE) for operating the current wind turbine design at the selected wind farm site is considerably lower than the average COE in the Netherlands, indicating high potential of commercially making profits. Environmental impact studies have also been done.
Optical absorption, scattering, and multiple scattering: Experimental measurements using food coloring, India ink, and milk
Authors: Lamelas Frank , Swaminathan Sudha
Published: January 2020

A series of optical experiments is used to illustrate color effects, absorption, and scattering. In the simple experiments, the intensity of red laser light is measured after the beam passes through samples with increasing concentrations of food dyes, black ink, and milk. The data are fitted with exponential functions, and similar attenuation is obtained with samples which are very different: black ink and white milk. Measured intensities and visual observations serve to illustrate the distinction between absorption, scattering, and attenuation. In more advanced experiments, attenuation coefficients and the mean attenuation length are measured. With milk samples, intensity measurements reveal a non-exponential concentration dependence which is a signature of multiple scattering. Finally, intensity as a function of distance is measured by scanning wedge-shaped samples of ink or milk across a detector. The effects of multiple scattering in milk are very pronounced in this case.
A simple digital phase-sensitive detector using AVR microcontroller
Authors: Nooruddin Mehbub A. K. , Roy Subhasish
Published: January 2020

We have described a simple and inexpensive digital phase-sensitive detector using a low-cost AVR microcontroller. To store a large number of data, we have added external memory (RAM) to the microcontroller. A message passing interface daemon-based software has been implemented to control the whole operation. Performance of the system has been tested using precise signals generated through a D/A converter controlled by an 8085 microprocessor. The phase resolution of the system has been reported to be better than 0.1°. This phase-sensitive detector would be very useful for low-budget laboratories that deal with low-frequency AC signal applications.
Effect of Auditory or Visual Working Memory Training on Dual-Task Interference
Authors: Kimura Takehide , Matsuura Ryouta
Published: January 2020

Dual-task interference causes many accidents. Working memory (WM) training has the potential to reduce dual-task interference. However, an effective method of WM training for reducing dual-task interference has not been established. This study aimed to examine whether WM training using auditory stimuli (auditory WM training) or visual stimuli (visual WM training) would more effectively reduce dual-task interference. Twenty-two young adults performed an N-back task with auditory or visual stimuli for auditory or visual WM training, for 2 weeks. The authors assessed dual-task interference before and after each training. The authors used a hierarchic multilevel model for these assessment parameters. As a result, visual WM training might be more effective for reducing dual-task interference than auditory WM training.
Campus attack and police violence alarm Indian academics
Authors: Kumar Sanjay
Published: January 2020

Many scientists are at odds with Hindu nationalists.
Florida center details fired scientists' links to China
Authors: Mervis Jeffrey
Published: January 2020

Report finds six cancer researchers didn't disclose Thousand Talents deals.
Cheap shots
Authors: Hand Eric
Published: January 2020

Cryo-EM reveals exquisite molecular structures—at high cost. A cheaper microscope could bring the resolution revolution to the masses.
Phase separation provides a mechanism to reduce noise in cells
Authors: Klosin A. , Oltsch F. , Harmon T. , Honigmann A. , Jülicher F. , Hyman A. A. , Zechner C.
Published: January 2020

Keeping the noise down

Protein concentrations in a cell fluctuate considerably because of stochasticity in gene expression and variations in the cell's microenvironment. How cells cope with concentration fluctuations when precision is important is unclear. Klosin
et al.
used a combination of theoretical and experimental work to demonstrate that phase-separated compartments can effectively reduce protein concentration noise in cells (see the Perspective by Riback and Brangwynne). The results suggest that phase separation provides a mechanism to enhance the robustness of biological systems.

Science
, this issue p.
464
; see also p.
364
Overhaul environmental risk assessment for pesticides
Authors: Topping C. J. , Aldrich A. , Berny P.
Published: January 2020

Align regulation with environmental reality and policy
The exposome and health: Where chemistry meets biology
Authors: Vermeulen Roel , Schymanski Emma L. , Barabási Albert-László , Miller Gary W.
Published: January 2020

Despite extensive evidence showing that exposure to specific chemicals can lead to disease, current research approaches and regulatory policies fail to address the chemical complexity of our world. To safeguard current and future generations from the increasing number of chemicals polluting our environment, a systematic and agnostic approach is needed. The “exposome” concept strives to capture the diversity and range of exposures to synthetic chemicals, dietary constituents, psychosocial stressors, and physical factors, as well as their corresponding biological responses. Technological advances such as high-resolution mass spectrometry and network science have allowed us to take the first steps toward a comprehensive assessment of the exposome. Given the increased recognition of the dominant role that nongenetic factors play in disease, an effort to characterize the exposome at a scale comparable to that of the human genome is warranted.
Tracking complex mixtures of chemicals in our changing environment
Authors: Escher Beate I. , Stapleton Heather M. , Schymanski Emma L.
Published: January 2020

Chemicals have improved our quality of life, but the resulting environmental pollution has the potential to cause detrimental effects on humans and the environment. People and biota are chronically exposed to thousands of chemicals from various environmental sources through multiple pathways. Environmental chemists and toxicologists have moved beyond detecting and quantifying single chemicals to characterizing complex mixtures of chemicals in indoor and outdoor environments and biological matrices. We highlight analytical and bioanalytical approaches to isolating, characterizing, and tracking groups of chemicals of concern in complex matrices. Techniques that combine chemical analysis and bioassays have the potential to facilitate the identification of mixtures of chemicals that pose a combined risk.
Learning from the past and considering the future of chemicals in the environment
Authors: Johnson Andrew C. , Jin Xiaowei , Nakada Norihide , Sumpter John P.
Published: January 2020

Knowledge of the hazards and associated risks from chemicals discharged to the environment has grown considerably over the past 40 years. This improving awareness stems from advances in our ability to measure chemicals at low environmental concentrations, recognition of a range of effects on organisms, and a worldwide growth in expertise. Environmental scientists and companies have learned from the experiences of the past; in theory, the next generation of chemicals will cause less acute toxicity and be less environmentally persistent and bioaccumulative. However, researchers still struggle to establish whether the nonlethal effects associated with some modern chemicals and substances will have serious consequences for wildlife. Obtaining the resources to address issues associated with chemicals in the environment remains a challenge.
Coherent scanning tunneling microscopy
Authors: Aiello Clarice D.
Published: January 2020

Ultrafast phase-stabilized optical pulses add temporal resolution to high spatial resolution
Confronting campus sexual assault
Sexual Citizens: A Landmark Study of Sex, Power, and Assault on Campus
Jennifer S. Hirsch and Shamus Khan
Norton, 2020. 432 pp.
Authors: Renzetti Claire M.
Published: January 2020

Inadequate sex education and socialization collide in built spaces that stymie consent
Diagnostic Accuracy of a Noninvasive Test for Detection of Helicobacter pylori and Resistance to Clarithromycin in Stool by the Amplidiag H. pylori+ClariR Real-Time PCR Assay
Authors: Pichon Maxime , Pichard Benoit , Barrioz Thierry , Plouzeau Chloé , Croquet Vincent , Fotsing Ginette , Chéron Alexandre , Vuillemin Éric , Wangermez Marc , Haineaux Paul-Arthur , Vasseur Philippe , Thiebault Quentin , Lefèvre Clémence , de Singly Anaïs , Cremniter Julie , Broutin Lauranne , Michaud Anthony , Silvain Christine , Burucoa Christophe
Published: January 2020

The noninvasive detection of
Helicobacter pylori
and its resistance to clarithromycin could revolutionize the management of
H. pylori
-infected patients by tailoring eradication treatment without any need for endoscopy when histology is not necessary. Several real-time PCR tests performed on stools have been proposed, but their performances were either poor or they were tested on too few patients to be properly evaluated. We conducted a prospective, multicenter study including 1,200 adult patients who were addressed for gastroduodenal endoscopy with gastric biopsies and who were naive for eradication treatment in order to evaluate the performance of the Amplidiag
H. pylori
+ClariR assay recently developed by Mobidiag (Espoo, Finland).
Anaesthetic management of a parturient with spondylothoracic dysostosis
Authors: Zbeidy Reine , Torres Buendia Nathalia , Souki Fouad G
Published: January 2020

Spondylothoracic dysostosis is a rare congenital disorder characterised by multiple vertebral malformations, shortening of the spine and fusion of the ribs at the costovertebral junction. These abnormalities create anaesthetic challenges due to difficult airway, severe restrictive lung disease and spine deformity necessitating a multidisciplinary approach and careful perioperative planning. We present the perianaesthetic management of a parturient with spondylothoracic dysostosis who successfully underwent preterm caesarean delivery under general anaesthesia with awake videolaryngoscopy-assisted tracheal intubation.
PD-L1 expression is an unfavourable prognostic indicator in Asian renal cell carcinomas
Authors: Yeong Joe , Zhao Zitong , Lim Jeffrey Chun Tatt , Li Huihua , Thike Aye Aye , Koh Valerie Cui Yun , Teh Bin Tean , Kanesvaran Ravindran , Toh Chee Keong , Tan Puay Hoon , Khor Li Yan
Published: January 2020

Background/aims

The programmed cell death receptor 1 (PD-1) checkpoint inhibitor, nivolumab, has been approved for the treatment of metastatic renal cell carcinoma (RCC). However, the understanding of the expression and distribution of PD ligand 1 (PD-L1) in the tumour immune microenvironment and its prognostic role in an Asian cohort is limited. Our group investigated PD-L1 protein expression in a cohort of Asian patients with RCC of mixed ethnicity, using two commercially available antibody clones.

Methods

E1L3N and SP263 anti-PD-L1 clones were used to categorise RCCs of various histological subtypes, diagnosed at our institution between 1995 and 2008, into PD-L1-positive or PD-L1-negative groups, based on a 1% Tumour Proportion Score (TPS) cut-off.

Results

In total, 267 (83%) clear cell (cc)RCC and 55 (17%) non-ccRCC cases were studied. Overall PD-L1 protein expression rates for the entire cohort were 13% and 8% for the E1L3N and SP263 clones, respectively. Patients bearing PD-L1-positive tumours experienced significantly decreased disease-free survival (DFS; E1L3N: p=0.01; SP263: p=0.03) but not overall survival, compared with those with PD-L1-negative tumours. Multivariate survival analysis further confirmed the results of the E1L3N clone (HR 1.85, 95% CI 1.10 to 3.13, p=0.02), but not SP263, after adjusting for pathological stage, histological subtype and grade. The addition of PD-L1 (E1L3N) TPS to clinicopathological features significantly increased the prognostic value for DFS (∆LRχ2=5.25; p=0.022), compared with clinicopathological features alone.

Conclusions

PD-L1 protein expression was associated with an unfavourable prognosis in our study cohort. PD-L1 (E1L3N) expression was an independent prognostic indicator of clinical outcome in all RCCs when using a 1% cut-off.
Nerve agents: emergency preparedness
Authors: Weir Alan George Andrew , Makin S , Breeze J
Published: January 2020

Nerve agents (NAs) are a highly toxic group of chemical warfare agents. NAs are organophosphorus esters with varying physical and chemical properties depending on the individual agent. The most recently developed class of NA is‘Novichok’, the existence of which was first revealed in the early 1990s, just before Russia signed the Chemical Weapons Convention. In 1984, Iraq became the first nation to deploy NA on the battlefield when they used tabun against Iranian military forces in Majnoon Island near Basra. The first terrorist use of an NA is believed to be the attack in Matsumoto, Japan, on 27 June 1994 by the Aum Shinrikyo doomsday cult. Symptoms and ultimate toxicity from NA poisoning are related to the agent involved, the form and degree of exposure, and rapidity of medical treatment. The classic toxidrome of significant exposure to NA comprises bronchorrhoea, bronchospasm, bradycardia and convulsions, with an onset period of as early as a few seconds depending on the mode and extent of exposure. If medical management is not instituted rapidly, death may occur in minutes by asphyxiation and cardiac arrest. In the UK, emergency preparedness for NA poisoning includes an initial operational response programme across all blue light emergency services and key first responders. This paper describes the development, pathophysiology, clinical effects and current guidance for management of suspected NA poisoning. It also summarises the known events in which NA poisoning has been confirmed.
Weak decays of triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$
Authors: Xing Ye
Published: January 2020

We study masses, lifetimes and weak decays of the triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯. The masses of tetraquark are explored under two different models. Further more, our calculations show a possibility of existence for the stable triply heavy tetraquark $$b{\bar{c}} b{\bar{q}} $$bc¯bq¯ with $$J^P=1^+$$JP=1+ which should be verified in experiment. Following the heavy quark expanding(HQE), the lifetimes of tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ can be expressed as the summation of different dimension operators. Particularly, we obtain the lifetimes of $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ at the next-to-leading order(NLO) given as $$\tau (T^{\{bb\}}_{\{{\bar{c}}{\bar{q}}\}})=0.70\times 10^{-12}s$$τ(T{c¯q¯}{bb})=0.70×10-12s. Besides, we construct the weak decays Hamiltonian of $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ in hadronic level under the SU(3) flavor symmetry. The discussion of the Hamiltonian can deduce the decay amplitudes and width relations of the tetraquarks. Following the choosing rules, we collect some golden channels for the mesonic decays of tetraquarks, which will be helpful to search for triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ in future experiments.
The laser gravitational compass: A spheroidal interferometric gravitational observatory
Authors: Ferreira Ivan S. , Frajuca C. , Magalhaes Nadja S. , Maia M. D. , Sousa Claudio M. G.
Published: January 2020

Using the observational properties of Einstein’s gravitational field it is shown that a minimum of four non-coplanar mass probes are necessary for a Michelson and Morley interferometer to detect gravitational waves within the context of General Relativity. With fewer probes, some alternative theories of gravitation can also explain the observations. The conversion of the existing gravitational wave detectors to four probes is also suggested.
Extragalactic neutrinos as tracers of dark matter?
Authors: Penacchioni A. V. , Civitarese O.
Published: January 2020

Neutrinos produced in extragalactic sources may experience flavor-oscillations and decoherence on their way to Earth due to their interaction with dark matter (DM). As a result, they may be detected in pointer-states other than the flavor states produced at the source. The oscillation pattern and the structure of the pointer-states can give us information on the characteristics of the DM and the kind of interaction that has taken place. From this perspective, neutrinos can be viewed as DM-tracers. We study the local evolution of neutrino flavor-eigenstates due to local effects produced by the presence of DM. To explore the sensitivity of the model, we consider different DM density profiles, masses and interactions. Starting from the eigenstates of the neutrino mass Hamiltonian, we construct flavor-states with the neutrino mixing-matrix in vacuum. We then include local interactions with DM, acting along the neutrino path towards the Earth, and analyze the resulting probabilities. In doing so, we adopt different DM density profiles, e.g. a constant, a local isotropic, and a Navarro–Frenk–White density distribution. Finally, by following the time-evolution of the flavor-states, we identify pointer-states and interpret the results in terms of the adopted DM model. In addition, neutrinos may experience changes in the oscillation parameters and resonances (MSW effect), the extent of which depends on the DM density profile. Thus, the presence of DM may enhance or suppress the oscillation pattern. The suppression of components of the neutrino wave-packet (decoherence effects) may also take place. The features of the calculated response seem to support the notion that these neutrinos can be taken as DM tracers. From a theoretical point of view, the coexistence and/or competition of decoherence and matter effects is sustained by the results.
Monoterpene-based metallophthalocyanines: Sustainable synthetic approaches and photophysical studies
Authors: Gonzalez Andreia C. S. , Damas Liliana , Aroso Rafael T. , Tomé Vanessa A. , Dias Lucas D. , Pina João , Carrilho Rui M. B. , Pereira Mariette M.
Published: January 2020

Tetra-substituted zinc(II) and copper(II) phthalocyanines bearing peripheral alkoxy-monoterpene groups were prepared by conventional vs. non-conventional synthetic approaches (ultrasound and microwave irradiation). The synthesis of (1[Formula: see text]-(–)-myrtenol (a) and (1[Formula: see text],2[Formula: see text],5[Formula: see text]-([Formula: see text]-menthol (b) derived phthalonitrile precursors was performed through ipso-nitro aromatic substitution reactions, with optimal conditions being obtained using ultrasound irradiation, which allowed us to achieve full conversions in 4.5 h, with isolated yields up to 74%. The subsequent cyclotetramerization of monoterpene-based phthalonitriles was carried out using Zn(II) or Cu(II) salts as metal templates, and also using conventional and non-conventional heating methods. Microwave-assisted synthesis was shown to be the most efficient approach, providing complete conversions in 1 h, yielding the target monoterpene-based metallophthalocyanines in up to 70% isolated yields. Furthermore, photophysical and photochemical studies revealed that Zn(II) phthalocyanines possess fluorescence quantum yields in the range of [Formula: see text] 0.27–0.29, while Cu(II) phthalocyanines exhibited room temperature phosphorescence. In addition, the monoterpene-based Zn(II) phthalocyanines led to high singlet oxygen quantum yields ([Formula: see text] 0.55–0.69).
A Comparative Study of Direct and Iterative Inversion Approaches to Determine the Spatial Shear Modulus Distribution of Elastic Solids
Authors: Liu Zhi , Sun Yanli , Deng Jianwei , Zhao Dongmei , Mei Yue , Luo Jianwen
Published: January 2020

This paper presents a comparative study of two typical inverse algorithms, i.e., direct and iterative inversion methods, to reconstruct the shear modulus distribution of linearly elastic solids. Both approaches are based on the finite element framework and compared utilizing both the simulated and experimental data. The reconstruction results demonstrate that both approaches are capable of identifying the nonhomogeneous shear modulus distribution of solids well. It can also be found that the direct inversion method is much faster than the iterative inversion method, whereas the iterative inversion method is capable of yielding better shear modulus ratio between the stiff inclusion and the soft background even with very high noise levels. Afterwards, a thorough comparison on the advantages and disadvantages of these two approaches has been performed. This comparative study provides useful information on the selection of the proper inverse scheme in estimating nonhomogeneous elastic property distribution of soft solids nondestructively.
New Analytical Solutions of Buckling Problem of Rotationally-Restrained Rectangular Thin Plates
Authors: Ullah Salamat , Zhang Jinghui , Zhong Yang
Published: January 2020

A double finite sine integral transform method is employed to analyze the buckling problem of rectangular thin plate with rotationally-restrained boundary condition. The method provides more reasonable and theoretical procedure than conventional inverse/semi-inverse methods through eliminating the need to preselect the deflection function. Unlike the methods based on Fourier series, the finite integral transform directly solves the governing equation, which automatically involves the boundary conditions. In the solution procedure, after performing integral transformation the title problem is converted to solve a fully regular infinite system of linear algebraic equations with the unknowns determined by satisfying associated boundary conditions. Then, through some mathematical manipulation the analytical buckling solution is elegantly achieved in a straightforward procedure. Various edge flexibilities are investigated through selecting the rotational fixity factor, including simply supported and clamped edges as limiting situations. Finally, comprehensive analytical results obtained in this paper illuminate the validity of the proposed method by comparing with the existing literature as well as the finite element method using (ABAQUS) software.
A Coupled Improved Element Free Galerkin-Finite Strip (IEFG-FS) Method for Free Vibration Analysis of Plate
Authors: Mousavi Hamed , Azhari Mojtaba , Saadatpour Mohammad Mehdi , Sarrami-Foroushani Saeid
Published: January 2020

In this paper, a coupling of improved element-free Galerkin (IEFG) method and semi-analytical finite strip (FS) method is presented for free vibration analysis of thin plates. This method is very easy to implement and has advantages of both IEFG and FS methods, so that IEFG method is used in sub-domain with complex geometry, and FS method is used for the remaining domains. The use of the FS method considerably reduces the analysis time, and the essential boundary conditions are easily enforced in FS sub-domain. In the IEFG method, the shape function does not have the Kronecker delta function property. Therefore, Lagrange multipliers method is used to satisfy the boundary conditions. Finally, five examples are presented to show the effectiveness of this work.
The Improved Interpolating Complex Variable Element Free Galerkin Method for Two-Dimensional Potential Problems
Authors: Deng Yajie , He Xiaoqiao , Dai Ying
Published: January 2020

In this paper, the improved interpolating complex variable moving least squares (IICVMLS) method is applied, in which the complete basis function is introduced and combined with the singular weight function to achieve the orthometric basis function. Then, the interpolating shape function is achieved to construct the interpolating trial function. Incorporating the IICVMLS method and the Galerkin integral weak form, an improved interpolating complex variable element free Galerkin (IICVEFG) method is proposed to solve the 2D potential problem. Because the essential boundary conditions can be straightaway imposed in the above method, the expressions of final dispersed matrices are more concise in contrast to the non-interpolating complex variable meshless methods. Through analyzing four specific potential problems, the IICVEFG method is validated with greater computing precision and efficiency.
Our Conflict with Transposable Elements and Its Implications for Human Disease
Authors: Burns Kathleen H.
Published: January 2020

Our genome is a historic record of successive invasions of mobile genetic elements. Like other eukaryotes, we have evolved mechanisms to limit their propagation and minimize the functional impact of new insertions. Although these mechanisms are vitally important, they are imperfect, and a handful of retroelement families remain active in modern humans. This review introduces the intrinsic functions of transposons, the tactics employed in their restraint, and the relevance of this conflict to human pathology. The most straightforward examples of disease-causing transposable elements are germline insertions that disrupt a gene and result in a monogenic disease allele. More enigmatic are the abnormal patterns of transposable element expression in disease states. Changes in transposon regulation and cellular responses to their expression have implicated these sequences in diseases as diverse as cancer, autoimmunity, and neurodegeneration. Distinguishing their epiphenomenal from their pathogenic effects may provide wholly new perspectives on our understanding of disease.
Excellent Electrochemical Performance of Potassium Ion Capacitor Achieved by a High Nitrogen Doped Activated Carbon
Authors: Chen Zhi , Li Wenlei , Yang Jian , Liao Jiaxuan , Chen Cheng , Song Yaochen , Ali Shah Syed Abbas , Xu Ziqiang , Wu Mengqiang
Published: January 2020

Supercapacitors, due to their unique high-power characteristics, are bound to occupy a place in the field of energy storage. Carbon-based supercapacitor is one of the most promising in all material systems. In this work, N-doped/graphene composite activated carbon (AC) is prepared through a facile method as electrodes for the comparison between an aqueous system and an organic system. The obtained AC shows high surface areas of 1600 m2 g−1 with a high N content of 11.7 wt% and is simultaneously applied to lithium-ions capacitor (LIC), sodium-ions capacitor (NIC) and potassium ion capacitor (KIC). Electrochemical evaluations indicated that the high N-doped activated carbon-based LIC, NIC and KIC possess different performance and energy storage mechanisms. The KIC exhibits the highest energy density of 50 Wh kg−1 at 0.4 A g−1 and the most stable cycle performance of three capacitors. This work reveals differences among the three types of ion capacitors, providing clues for the development of high power-energy and long life ion supercapacitors. Moreover, KIC has better performance than LIC, and the reserve of K is much higher than Li, which makes KIC a better application prospect.
Selective Allylic Oxidation of Terpenic Olefins Using Co-Ag Supported on SiO2 as a Novel, Efficient, and Recyclable Catalyst
Authors: Aberkouks Abderrazak , Mekkaoui Ayoub Abdelkader , Ait Ali Mustapha , El Firdoussi Larbi , El Houssame Soufiane
Published: January 2020

Co-Ag supported on the SiO2 catalyst was synthesized by the sol-gel method and characterized using XRD, FT-IR, TG-DTG, BET, CV, and SEM/EDX analysis. The catalytic performance of the resulting catalyst was examined by the oxidation of mono and sesquiterpenic olefins using hydrogen peroxide and tert-butyl peroxide as oxidant agents. Various parameters such as catalyst amount, temperature, and solvents have been studied. The Co-Ag supported on the SiO2 catalyst showed a high activity, selectivity, and recyclability for the selected oxidation reaction.
Lateral Flow Immunoassay for Naked Eye Detection of Mycobacterium tuberculosis
Authors: Ariffin Nazifah , Yusof Nor Azah , Abdullah Jaafar , Abd Rahman Siti Fatimah , Ahmad Raston Nurul Hanun , Kusnin Norzila , Suraiya Siti
Published: January 2020

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. Detection and control of infectious diseases is a major problem, especially in developing countries. Lateral flow immunoassay (LFIA) has been introduced as a handheld immunoassay-based point-of-care platform for an automated detection of TB. The CFP10-ESAT6 antigen of M. tuberculosis was used as the target in early detection of TB using LFIA strip-based POC strategy. An interesting platform based on optical signals is implemented as a colour change in the detection area that is visible to the naked eye. The gold nanoparticles (AuNPs) were used as the colour probe for the detection of a target of interest. The high-resolution transmission electron microscopy (HRTEM) image and ultraviolet-visible spectrophotometer (UV-Vis) analysis confirmed that the synthesized AuNPs were appropriate for the immunoassay designed. The platform consists of AuNPs conjugated with specific antibodies (Ab) to capture the antigen of M. tuberculosis. Under the capillary effect, sandwich immunoreactions of AuNP-Ab-antigen were performed on the test pad of the immunostrip, which can be observed by the colour signal on the test line of the strip with a short assay time. Furthermore, the newly developed biosensor was utilized in CFP10-ESAT6 antigen detection in human sputum specimens with satisfactory results. The characteristic coloured bands enable visual detection (naked eye) of target analyte without instrumentation. This noninvasive diagnose system which is sputum-based detection could provide user-friendly and affordable diagnostic tests in developing countries.
Differential Diagnostic Reasoning Method for Benign Paroxysmal Positional Vertigo Based on Dynamic Uncertain Causality Graph
Authors: Dong Chunling , Wang Yanjun , Zhou Jing , Zhang Qin , Wang Ningyu
Published: January 2020

The accurate differentiation of the subtypes of benign paroxysmal positional vertigo (BPPV) can significantly improve the efficacy of repositioning maneuver in its treatment and thus reduce unnecessary clinical tests and inappropriate medications. In this study, attempts have been made towards developing approaches of causality modeling and diagnostic reasoning about the uncertainties that can arise from medical information. A dynamic uncertain causality graph-based differential diagnosis model for BPPV including 354 variables and 885 causality arcs is constructed. New algorithms are also proposed for differential diagnosis through logical and probabilistic inference, with an emphasis on solving the problems of intricate and confounding disease factors, incomplete clinical observations, and insufficient sample data. This study further uses vertigo cases to test the performance of the proposed method in clinical practice. The results point to high accuracy, a satisfactory discriminatory ability for BPPV, and favorable robustness regarding incomplete medical information. The underlying pathological mechanisms and causality semantics are verified using compact graphical representation and reasoning process, which enhance the interpretability of the diagnosis conclusions.
Jamming Prediction for Radar Signals Using Machine Learning Methods
Authors: Lee Gyeong-Hoon , Jo Jeil , Park Cheong Hee
Published: January 2020

Jamming is a form of electronic warfare where jammers radiate interfering signals toward an enemy radar, disrupting the receiver. The conventional method for determining an effective jamming technique corresponding to a threat signal is based on the library which stores the appropriate jamming method for signal types. However, there is a limit to the use of a library when a threat signal of a new type or a threat signal that has been altered differently from existing types is received. In this paper, we study two methods of predicting the appropriate jamming technique for a received threat signal using deep learning: using a deep neural network on feature values extracted manually from the PDW list and using long short-term memory (LSTM) which takes the PDW list as input. Using training data consisting of pairs of threat signals and corresponding jamming techniques, a deep learning model is trained which outputs jamming techniques for threat signal inputs. Training data are constructed based on the information in the library, but the trained deep learning model is used to predict jamming techniques for received threat signals without using the library. The prediction performance and time complexity of two proposed methods are compared. In particular, the ability to predict jamming techniques for unknown types of radar signals which are not used in the stage of training the model is analyzed.