bluuebunny/crossref_metadata_2025 huggingface dataset:
Buckling of steel column with box section considering residual stress under local fire
Authors: Wu L L , Zhang Y , Zhang H D , Lu Q
Published: October 2021

In order to study the fire resistance performance of the box section steel column considering the welding residual stress under local high fire temperature, a finite element model of the box section steel column was established by using ABAQUS software, and the generation of welding residual stress was simulated. Based on the simulation results, the stable bearing capacity of the box section steel column considering welding residual stress under three kinds of local fire condition was analyzed. The results show that the tensile stress is highly concentrated in the weld seam, and the welding residual compressive stress with wide distribution and uniform amplitude is generated in other parts. Under the three kinds of local fire conditions, the stable bearing capacity of the component decreases with the increase of temperature. When the maximum temperature of the component is greater than 566 °C, the stable bearing capacity of the component decreases significantly, and the decline coefficient reaches 0.62. When the fire temperature is 436°C-658°C, the stable bearing capacity of the component is the least under condition 3, which is the most unfavorable condition of the component.
Influence of welding deformation on anti-collapse performance of single-layer reticulated shell structures with prestressed cables
Authors: Fu Y Q , Yang X D , Zhang H D , Wang Y M
Published: October 2021

In this paper, the ABAQUS finite element software is used to model and analyze the single-layer reticulated shell structure. And the method of removing the constraints of key components is used to analyze the anti-continuous collapse performance of this reticulated shell structure under the action of geometric defects and welding deformation. Welding deformation is mainly caused by welding and prestressed cable tensioning of single-layer reticulated shell. The results show that the removal of the key columns under the reticulated shell will lead to the continuous collapse of the upper part, which leads to the continuous collapse of the whole structure, and the welding deformation can make the continuous collapse of the whole reticulated shell more obvious. Thus determining the influence of geometric defects and temperature shrinkage deformation on the anti-continuous collapse performance.
Assessment of the global stability of three-limbed steel tube latticed column using finite element modelling
Authors: Fu Y D , Dai X Y , Zhang H D , Shang K G
Published: October 2021

In order to study the stability performance of the three-limbed steel tube latticed column, the finite element numerical analysis method based on the structural stability theory is adopted. Firstly, the linear analysis of the three-limbed steel tube latticed column without diagonal lacing bar is carried out, and the calculation method of elastic buckling load considering the influence of shear deformation is obtained. Then, the elastic buckling analysis and elastoplastic buckling analysis three-limbed steel tube latticed column with diagonal lacing bar are carried out. The elastic buckling load and elastoplastic buckling load of three-limbed steel tube latticed column with diagonal lacing bar are studied when only the global initial geometric defects, only the member initial geometric defects, and both kinds of defects are considered at the same time. The results show that the direct finite element analysis method can be used to calculate the elastic buckling load of three-limbed steel tube latticed column with diagonal lacing bar, and the error is 6.67%. In the elastic analysis of three-limbed steel tube latticed column with diagonal lacing bar, the column global stability mainly depends on the global initial geometric defects, and the member initial geometric defect is negligible. And when two kinds of defects are applied at the same time, the structural buckling load is reduced by less than 0.20% compared to the global initial geometric defects. In the elastoplastic analysis, the column global stability is determined by both the global initial geometric defect and the member initial geometric defect. When both defects are applied at the same time, the structural buckling load decreases by less than 0.65% compared to the global initial geometric defect only, and 7.60% compared to the member initial geometric defects only. It can be concluded that there is little difference in the overall stability bearing capacity between the two kinds of defects.
Study on grain size control technology of 304L austenitic stainless steel
Authors: Wang Y , Sun D D , Bai Y P , Pang Z X
Published: October 2021

In order to solve the problem of mischcrystal in 304L stainless steel with thickness of over 40mm, a series of critical process parameter were studied in laboratory and trial product, such as rolling cycle, temperature of recrystallization controlled rolling, holding time and cooling mode after rolling. The results show that the deformation at 1050°C and 950°C has no significant effect on the recrystallization ratio. The steel plate was dephosphorized by descaling box after the steel was taken out of the heating furnace. After three passes of longitudinal rolling, the steel plate was turned to cross rolling. Before the cross rolling, the surface of the middle slab was dephosphorized, while the remaining passes were not dephosphorized. Static recrystallization could be completed after a short time of warming. The effects of temperature and time on grain growth were compared under the same deformation conditions, it is found that temperature is a sensitive factor for grain growth. The higher the temperature is, the process of recrystallization and grain growth almost happens at the same time. The lower the temperature, the higher the proportion of recrystallization can be maintained, and the abnormal grain growth can be inhibited, which can effectively improve the problem of mischcrystal.
Numerical simulation analysis of tunnel construction mechanical response considering shotcrete hardening process
Authors: Nie Z H , Jin X G , Luo W
Published: October 2021

At present, tunnel construction mechanics studies basically do not consider the hardening process of shotcrete. In order to reveal the hardening process of sprayed concrete in a sulfate environment and the influence of sulfate corrosion on tunnel stability, the model parameters were determined in combination with the change rules of mechanical parameters of shotcrete obtained in the author’s experiment. The MIDAS GTSNX finite element software was used to analyze the effect of the hardening process of the shotcrete, chemical corrosion, and physical corrosion of sulfate on the displacement and stress of the surrounding rock of the tunnel. The results show that considering the hardening process of shotcrete, the growth rate of tunnel clearance displacement increases, and the stress increase slows in the early stage of shotcrete (The tunnel lining structure is applied, and the second step of excavation is carried out). With the increase of time or the construction steps, the stress of shotcrete increases significantly, and the clearance displacement growth rate significantly decreased. The influence of the chemical and physical corrosion of shotcrete on the stress and displacement of the surrounding rock of the tunnel is similar to considering the hardening process of shotcrete. indicating that sulfate corrosion has an inhibitory effect on the hardening process of shotcrete and increased construction risk.
Experimental study on the application of red mud to controlled low strength material made of excavated soil
Authors: Kong X H , Cui S , Chen L H , Wang X H
Published: October 2021

To improve the resource utilization of solid waste, excavation abandoned soil and red mud, a by-product of alumina industry, were introduced into the preparation of controlled low strength material (CLSM). By carrying out the flowability test, bleeding test and compressive strength test, the relationship between properties of CLSM mixture and the amount of red mud was analysed. The experiment results indicate that the flowability and bleeding rate of the mixture decrease with the increase of red mud content. When the red mud content is less than 20%, the mixture shows good flowability. The addition of red mud can accelerate the completion time of bleeding and play a positive role in the bleeding stability of the mixture. When the red mud content is 10%, the strength of the mixture reaches the maximum, while the strength of the mixture with other contents decreases with the increase of red mud content. For the CLSM made of excavated soil, red mud has a good application prospect in terms of bleeding stability and strength.
Effect of residual stress in longitudinal and transverse weld on global stability of box section steel column
Authors: Li L , Zheng F H , Zhang H D , Fu Y Q
Published: October 2021

In order to study the influence of welding residual stress on the global stability of box section steel column, the simulation of the side effects from the welding process of Q345 box section steel column by ABAQUS thermal-structure coupling analysis was conducted. A temperature-displacement explicit analysis step was established, and the residual stress caused by the temperature difference of the welding specimen was simulated by applying the body heat flux directly to the solid element within the same thickness range of the weld seam and defining the load amplitude; The calculated welding residual stress was taken as the initial defect of the structure and the global stable bearing capacity of the box section steel column was solved by the arc length method. Considering the influence of thickness and welding residual stress on the global stability of box section steel column, the calculation results of 12 finite element models were compared. The results show that under the same body heat flux, the residual stress of steel columns with different thicknesses during welding is different, and the maximum value can reach 791MPa; Under the condition of the same residual stress, the global stability bearing capacity of the box section steel column will also change irregularity with the change of thickness, and the global stability bearing capacity can be reduced by 3.07% compared with that no residual stress.
Raman Spectroscopy Studies of TRISO-Particle Fuel
Authors: Krajewska Zuzanna M , Gudowski W
Published: October 2021

Development of High Temperature Gas-cooled Reactors opens new horizons for nuclear power in Poland. Good understanding of the failure-free performance of Tri-structural ISOtropic (TRISO)-particle fuel is a key for the safe and efficient operation of those reactors. It is also essential to avoid potential errors in TRISO fuel production for the HTR program in Poland. In a longer perspective to ensure the highest possible quality of the TRISO fuel fabrication and storage before loading into the reactor core, it is necessary to control the quality of the TRISO-particle fuel in order to understand the aging of fresh fuel. Nevertheless, such a solution requires to determine whether the passage of time affects the occurrence of changes in TRISO fuel layer’s structure and at the same time whether it contributes to increasing the probability of damage to the examined fuel material. For this purpose, it is planned to perform an experiment on different types of TRISO fuel, produced in different periods of time. The comparative analysis will be based mainly on the experimental method of Raman spectroscopy.
Corrosion Phenomena of High Temperature Alloys by Helium Impurities in the Primary Coolant of HTGR
Authors: Wang Q , Zheng W , Yin H , Li S , He X , Ma T
Published: October 2021

The primary coolant circuit of the high temperature gas-cooled reactor (HTGR) contains trace impurities. A nickel base alloy would corrode when exposed to an atmosphere at a high temperature and for a long time. The protective oxide scale formed by chromium is an important factor to prevent severe corrosion of high temperature alloys. Corrosion tests were conducted on Inconel 617, Incoloy 800H, Hastelloy X, and T-22, which are commonly used in the steam generator of HTGR. The alloys were exposed to helium with trace impurities for 48 hours at 950°C. The corrosion results were analyzed by weighing, scanning electron microscopy (SEM) and electron probe microanalyzer (EPMA). All the four alloys formed oxide scales in this atmosphere, but they differ in the capacity to resist corrosion. Therefore, the carbon transfer phenomenon observed in this experiment varies for the different alloys. In addition, for Cr in Inconel617, the expected depletion phenomenon near the corrosion layer occurred, which is consistent with the results from theoretical analysis.
Accurate Nodal Diffusion Modelling on the High Temperature Test Reactor (HTTR)
Authors: Rizki M. , Oktavian  , Seker Volkan , Kochunas Brendan , Xu Yunlin
Published: October 2021

The High Temperature Test Reactor is a 30-MWth helium-cooled, graphite-moderated, prismatic-type gas reactor developed by the Japan Atomic Energy Agency (JAEA). The hexagonal shape of fuel blocks in the HTTR core combined with complex inner structures containing TRISO particles results in the double-heterogeneity effect that increases the simulation challenge of the reactor. This research has a goal to accurately model the HTTR fuel blocks employing the standard two-step procedure of a reactor analysis: employ a lattice physics calculation to generate homogeneous cross sections and use them in a nodal diffusion calculation. The implementation of the diffusion approximation results in a faster calculation with acceptable accuracy compared to the high-resolution lattice calculation. An advanced method called Triangular Polynomial Expansion Nodal (TriPEN) method was used in this work for the nodal diffusion calculation to accurately model the flux discontinuity effect between blocks by generating discontinuity factors in each surface and corner point. To do this, the heterogeneous solutions obtained from the lattice physics calculation, which is done by Serpent Monte Carlo in this case, are utilized by TriPEN to generate the discontinuity factors. Due to its capability to simulate any reactor geometry with a high-resolution, the results generated from Serpent calculation were also used as the reference cases for this work. In this work, the TriPEN method is implemented in the PARCS core neutronic module inside AGREE, a U.S. N.R.C. Multiphysics code system for the High Temperature Reactor (HTR). Test cases conducted for this method involved the original design of the HTTR. The 4-hex model built consisted of the central control-rod block of HTTR together with 6 of the half-fuel-blocks surround it. The differences in material composition in each assembly block in HTTR resulted in flux discontinuity effects on the assembly block interfaces. To correct this discrepancy, discontinuity factors were applied in order to make the homogenous solutions from the nodal calculation agree with the heterogeneous solutions from the lattice physics calculation. Applying this procedure to the HTTR nodal models, TriPEN is able to produce exact results in the eigenvalue compared to Serpent calculation, the rod worth calculated perfectly matched the reference, and the flux and power distribution only has negligible discrepancies.
Performance Improvement for Multi-recycling HTGR Incorporated with MA burning
Authors: Fukaya Y , Goto M , Yan X L
Published: October 2021

Multi-recycling HTGR has been investigated by JAEA in order to reduce the environmental burden and non-proliferation of Pu. In the previous study, it is found that all actinoids except neptunium, which is not problematic from the viewpoint of toxicity and proliferation, can be recycled. However, the cycle length is slightly decreased compared with uranium fueled core due to the cumulated fertile TRU in the fuel composition. In the present study, Pu recycling HTGR is designed to incorporate with MA burning. As a result, the cycle length is increased by approximately 15% compared with TRU multi-recycling core, and if the MA burner can be achieved by IFR, the cost is decreased by 0.14 yen/kWh.
Optimization of PeLUIt-150 Conceptual Design
Authors: Setiadipura T , Luthfi W , Bakhri S , Suwoto  , Zuhair  , Li Z , Sun Y
Published: October 2021

A 150MWt pebble bed high temperature reactor, called PeLUIt-150, is proposed as a solution for distributed energy demand including the electricity and various co-generation potentials. In current study an optimization of the design is performed. The optimization includes its optimum power density to have a compact core design including the height-to-diameter (H/d) ratio. As several computer codes is used in this study, PEBBED-THERMIX codes, comparison of results from different code is also discussed. Constrain of the design at current stage are the maximum fuel temperature under depressurized loss of forced cooling (DLOFC) accident which represent the passive performance of the core, and discharge burnup which represent the fuel utilization performance of the core. Current study achieves an optimized design with core diameter and height of 260 cm and 601.11cm, a total active core volume of 31.9 m3. The average power density is 4.7W/c m3 with discharge burnup of 80.82MWd/Kg and the maximum fuel temperature after DLOFC is 1619.9°C.
Impact of Different Nuclear Data Library on Control Rod Reactivity Worth Calculation of Small Pebble Bed Reactor
Authors: Suwoto  , Adrial H , Setiadipura T , Zuhair  , Bakhri S
Published: October 2021

One of the main critical issues on a nuclear reactor is safety and control system. The control rod worth plays an important role in the safety and control of nuclear reactors. The control rods worth calculation is used to specify the safety margin of the reactor. The main objective of this work is to investigate impact of different nuclear data libraries on calculating the control rod reactivity worth on small pebble bed reactor. Calculation of the control rod reactivity worth in small high temperature gas cooled reactor has been conducted using the Monte Carlo N-Particle 6 (MCNP6) code coupled with a different nuclear data library. Famous evaluated nuclear data libraries such as JENDL-40u, ENDF/B-VII.1 and JEFF-3.2 continuous cross section-energy data libraries were used. The overall calculation results of integral control rod worth show that the ENDF/B-VII.1, JENDL-40u and JEFF-3.2 files give values of - 17.814%☐k/k, -18.0204 %☐k/k and -18.0267%☐k/k, respectively. Calculations using ENDF/B-VII.1 give a slightly lower value than the others, while the JENDL-4.0u file gives results that are close to JEFF-3.2 file. The different nuclear data libraries have a relatively small impact on the control rod worth of small pebble bed reactor. Accurate prediction by simulation of control rod worth is very important for the safety operation of all reactor types, especially for new reactor designs.
Influence of Coiling Direction of Helical Tube Bundles on the Thermal-Hydraulics of the HTGR Steam Generator
Authors: Gao Weikai , Xie Xiaoyang , Li Xiaowei , Wu Xinxin
Published: October 2021

Helical tube bundles were usually adopted in the steam generators (SGs) or intermediate heat exchangers (IHXs) of high temperature gas-cooled reactors (HTGRs). Heat transfer tubes in neighboring tube layers can be coiled in the same direction or in the opposite direction. The coiling direction has influences on the thermal-hydraulic performances of the SGs or IHXs. The cross flow convection over helical tube bundles with neighboring tube layers having the same coiled direction and opposite coiled direction were numerically investigated. Reynolds stress model with standard wall functions was used for the turbulence modeling. For a helical tube bundle with neighboring layers coiled in the same direction (parallel tube layers), the tangential velocity along the coiled circumferential direction could be observed obviously. For a helical tube bundle with neighboring layers coiled in the opposite direction (crossed tube layers), there is no average tangential velocity of the whole flow filed. And the streamlines of the fluid are very complex. The flow resistances and heat transfer coefficients over helical tube bundle with parallel tube layers and crossed tube layers were compared. Although the heat transfer over helical tube bundles with crossed tube layers was 9.39% smaller than that with parallel tube layers, the pressure drop over tube bundle with crossed tube layers was much smaller compared with those with parallel tube layers.
Simulation System for PeLUIt 150 MW Nuclear Reactor by using vPower
Authors: Yunus M , Budiman A A , Zhe S , Kiswanta  , Chunlin W , Subekti M , Bakhri S , Jun S
Published: October 2021

In developing the PeLUIt 150 MW nuclear power plant based on the High Temperature Gas-cooled Reactor (HTGR) technology, with the helium-coolant and output thermal power of 150 MW, the PeLUIt simulator is also developed for training the operators and educating other technical personnel. Referred to the balance of plant (BOP) design of the PeLUIt, the simulator utilized the vPower simulation platform to simulate the secondary loop for power generation with a water-steam Rankine cycle. The paper focuses on developing the secondary loop’s main components: steam generator, steam turbine, condenser, deaerator, and feedwater pump. The reactor module in the primary loop is simplified as a heat source with 150 MW output. The steam generator that connects the primary and secondary loops is modeled with the heat exchanger module by transferring heat from helium to water/steam. Meanwhile, pressure and flow parameters can also be simulated for both helium and water/steam flows in steady-state and transient operating conditions. The steady-state simulation results are almost the same as the design data. The differences in the main steam temperature, feedwater pressure, and feedwater temperature, are 0.03%, 0.53%, and 0.02%, respectively. Meanwhile, the transient condition carried out in the loss of coolant accident showed a decrease in flowrate of 43.31 kg/s and an increase in temperature of feedwater and main-steam of 52.32 and 15.38 °C, respectively. In addition, there was a pressure drop of around 10.37 (feedwater) and 10.16 MPa (main-steam).
Modelling of FPGA-based Reactor Protection Systems of an Experimental Power Reactor
Authors: Suryono T J , Sudarno  , Santoso S , Maerani R
Published: October 2021

The reactor protection system of nuclear power plants including an experimental power reactor which will be built by Indonesia is a safety system that actuates the control rods to be inserted in the reactor core to absorb the neutron to stop the fission reaction and then shut down the reactor (reactor trip). The reactor protection system (RPS) is actuated when the level of signals from the sensors of important components in the reactors deviates from the setpoint determined in the bi-stable processor of the RPS. RPS for the experimental power reactor has 3 redundant channels for reliability and to minimize fake signals from the sensors due to electrical noise. It can be done by selecting the channels in local coincidence logic in the RPS by voting 2 of 3 channels which are eligible to generate actuation signals to trip the reactor. Recently, the RPSs are based on the programmable logic controller (PLC). However, now the trend changes to FPGA-based RPS because of its simplicity and reliability. This paper investigates the model of the FPGA-based RPS for an experimental power reactor and the functionality of each component of the model. The results show that the model can represent the functionality of RPS for the experimental power reactor.
Effect of mixing temperature in the development of green polypropylene – coal bottom ash composite slab
Authors: Mohd Yapandi Md Fauzan Kamal , Zainal Mohamad Fetri , Yusop Hanafi , Latif Famiza , Bonnia Noor Najmi , Jalil Mohammad Noor , Sukhairul Zaman Nur Zaqira Izzati
Published: October 2021

Coal bottom ash (CBA) is a residue produced from the burning of pulverized coal for electricity generation. The high porosity and low abrasion resistance of CBA hindered its commercialization; thus tonnes of CBA were discharged in landfills and surface impoundments. Considering the adverse social and environmental issues associated with disposal management, it is imperative to optimize the utilization of CBA. About 30% of CBA were homogeneously blended with Polypropylene (PP) to produce a “green” PP-CBA composite slab. The influences of mixing temperatures on the physical, chemical and mechanical properties of the fabricated slabs were examined in the study. FESEM micrographs illustrated a smoother surface with a low density of voids in composite systems mixed at low temperatures (190°C). Moisture content was retained in the PP-CBA matrix and imparted supplementary strength to the composite. The relatively amorphous state of the composite allowed for easier dispersion of molecules under applied stress. From the tests, PP-CBA composite slabs mixed at 190°C exhibited the largest drop impact energy and ideal physical and structural properties.
Assessing biofouling in Ocean Thermal Energy Conversion (OTEC) power plant – A review
Authors: Zainal Abidin Mohd Zaki , Muhd Rodhi Miradatul Najwa , Hamzah Fazlena , Ghazali Nurul Aimi
Published: October 2021

Ocean Thermal Energy Conversion (OTEC) harnesses thermal energy stored at different seawater depths via power generation from a thermodynamic closed-loop cyclical system. Apart from its consistent energy generation, it could be diversified into other side industries, making OTEC an attractive and sustainable source of renewable energy. However, the process that utilises seawater as its main fluid is exposed to biofouling deposition due to unwanted growth and accumulation of biological elements on any contact surfaces, potentially affecting its efficiency and damaging equipment in the process. Considering that biofouling is an inevitable condition that may not be eliminated, a comprehensive study for assessing potential biofouling growth and deposition mechanism is a crucial step for strategizing effective biofouling management in a commercial and large-scale OTEC power plant facility. This review paper focuses on evaluating suitable biofouling assessment techniques specifically for a large-scale OTEC power plant facility. This is achieved by evaluating previous and proposed biofouling assessment techniques relevant to OTEC systems by focusing on their implementation under a realistic OTEC setup. The initial study indicated that the potential of biofouling deposition may be unavoidable in some sections in all OTEC models, despite biofouling-free design consideration. Previous OTEC biofouling studies were evaluated with reported physical and biological assessment approaches indicated the need to further improve these techniques especially in continuous and non-destructive methods. Therefore, several biofouling monitoring systems reported from other water treatment industries were considered for the OTEC systems, with findings indicated the importance of considering important OTEC operational parameters for feasible and robust biofouling monitoring systems. Two major parameters which are seawater intake flow rate and temperature variation at different seawater intake levels were evaluated under OTEC operational evaluation by considering examples of practices conducted in cooling water systems in the power plant industry. A realistic biofouling monitoring setup for mimicking continuous changes in biofouling deposition is required, in this case by side-connecting an operated OTEC power plant facility with a pilot plant setup or a side sampler. This step allows the application of proposed biofouling monitoring techniques under a realistic and uninterrupted biofouling deposition setup.
Wind, hydro and solar energy challenges for Technical Vocational and Training (TVET) electrical entrepreneur in Malaysia: A review
Authors: Harun G , Sarip S , Abdul Fatah A Y , Kaidi H M , Abd Rahim N
Published: October 2021

Renewable energy is one of the alternative energy resources in Malaysia to replace fossil fuel use, which is an important issue that needs to be established. Some of the possible renewable energy sources are wind, hydro and solar. Since 2019, various incentives announced by the Malaysian Ministry of Energy and Natural Resources (KeTSA) to enhance renewable energy development which is in line with Government Energy policy. However, today, in contrast to the participation of investors and international contractors, the presence of entrepreneurs and domestic workers in this sector is feeble. In this regard, the Technical Vocational and Training (TVET) institution is seen to have the potential to minimize this crisis by creating competent, skilled and competitive electrical entrepreneurs for the field of renewable energy. This paper explores the ability of TVET electrical entrepreneurs to participate in renewable energy businesses. Based on the literature on energy entrepreneur development, it was found that the TVET electrical entrepreneur faces four challenges, namely financial, technology costs, logistics and government support. The proposed future development of renewable energy is in Mini-hydro and solar photovoltaic (PV), while wind power does not seem viable to TVET electricity entrepreneurs.
The effect of corn stalk fiber loading on tensile properties and absorption ability on polybutadiene adipate terephalate composite.
Authors: Mohamad Rosdi M H H , Ahad N A
Published: October 2021

The natural fiber have recently become attractive and been widely used as reinforcement material to replace synthetic fiber as a concern to environmental issue. However, there are some of natural fiber unable to perform well as reinforcement material due to their natural properties. In this research study, the corn stalk fiber was selected as natural fiber reinforced with polybutadiene adipate terephalate (PBAT) to form bio-composite materials. There are two type of PBAT used which are in pellets form and powder form. The objectives of using different type of PBAT are to identify their compatibility with filler and the dispersion of corn stalk fiber in both forms of matrix. Then, the both type of PBAT also compounded with difference loadings of corn stalk fiber. Lastly, their effect on tensile properties and absorption ability were identified. After the test is run, the composite of neat PBAT in powder form shows highest tensile strength and elongation at break but lowest in water absorption percentage compared to others. However, the composition of pellets PBAT with 30wt% of corn stalk fiber shows highest percentage of water absorption compared to others.
Effect of corrugated minichannel variable width on entropy generation for convective heat transfer of alpha-Alumina-water nanofluid
Authors: Muhammad N M , Sidik N A C , Saat A , Asako Y , Japar W M A A , Musa G H , Yuof S N A
Published: October 2021

Energy management and sustainability in thermal systems require maximum utilization of resources with minimal losses. However, it is rarely unattainable due to the ever-increasing need for a high-performance system combined with device size reduction. The numerical study examined convective heat transfer of an alpha-Alumina-water nanofluid in variable-width corrugated minichannel heat sinks. The objective is to study the impact of nanoparticle volume fractions and flow area variation on the entropy generation rate. The determining variables are 0.005 – 0.02 volume fractions, the fluid velocity 3 – 5.5 m/s and heat flux of 85 W/cm2. The numerical results show an acceptable correlation with the experiment results. The results indicate the thermal entropy production drop with an increase in nanoparticles volume fraction. Contrastingly, the frictional resistance entropy suggests the opposite trend due to the turbulence effect on the fluid viscosity. The induction of Alumina-Water nanofluid with enhanced thermal conductivity declined the entropy generation rate compared to water alone. The increase in width ratio by 16% between the cases translates to at least a 9% increase in thermal entropy production. The outcome of this study can provide designers and operators of thermal systems more insight into entropy management in corrugated heatsinks.
Organic Rankine Cycle (ORC) as waste heat recovery system for micro-cogeneration: A preliminary study
Authors: Saadon S
Published: October 2021

Although the energy consumption pattern has been optimized, the main problem facing by energy revolution is the low conversion efficiency of renewable energy and waste heat. Among the utilization technologies of these waste heat, organic Rankine cycle (ORC), which has characteristics of simple structure and high efficiency is chosen as the potential candidate to overcome this situation. However, ORC is facing several limitations including having low turbine performance leading to low power production. Additionally, the design of ORC and the heat recovery system should be improved to reduce the investment cost. One of the ways to increase the performance of this ORC is to design ORC waste heat recovery system for cogeneration. Thus, this study will be focused on to identify the effect of different heat exchanger positions to the ORC thermal performance and to investigate the effect of integrating ORC for cogeneration. In order to achieve this, identification of the suitable heat exchanger for ORC will be performed by modelling and simulation to predict the effect of the new design to the ORC thermal performance. Then, the improved novel ORC design will be integrated to a cogeneration system to simulate the power produced by the combined system.
Comparative phylogeography study reveals introgression and incomplete lineage sorting during rapid diversification of Rhodiola
Authors: You Jianling , Lougheed Stephen C , Zhao Yao , Zhang Guojie , Liu Wensheng , Lu Fan , Wang Yuguo , Zhang Wenju , Yang Ji , Qiong La , Song Zhiping
Published: October 2021

Background and Aims

Many plant taxa in the Qinghai–Tibetan Plateau (QTP) and the Hengduan Mountains (HM) radiated rapidly during the Quaternary but with frequent secondary contact between diverging populations. Incomplete lineage sorting and introgressive hybridization might be involved during the rapid radiation, but their effects on phylogeography have not been fully determined.

Methods

We investigated the chloroplast DNA (cpDNA)/internal transcribed spacer (ITS) sequence variations of 611 samples of Rhodiola bupleuroides, R. discolor, R. fastigiata and R. chrysanthemifolia from the QTP and HM to compare the phylogeographic patterns between the four species with different evolutionary histories, geographic ranges and reproductive modes.

Key Results

The divergence times of these species were consistent with the last peak of in situ speciation in the HM. While closely related species exhibited different phylogeographic patterns, they shared several ribotypes and haplotypes in sympatric populations, suggesting introgressive hybridization. A significant phylogenetic discordance between ribotypes and haplotypes was detected in three species, implying incomplete lineage sorting. Rhodiola discolor houses an extraordinary richness of cpDNA haplotypes, and this finding may be attributed to adaptive radiation.

Conclusion

In addition to geographic isolation and climate oscillations during the Quaternary, both introgressive hybridization and incomplete lineage sorting play important roles in species that experienced rapid diversification in the QTP and HM.
Measuring Vaccine Efficacy Against Infection and Disease in Clinical Trials: Sources and Magnitude of Bias in Coronavirus Disease 2019 (COVID-19) Vaccine Efficacy Estimates
Authors: Williams Lucy R , Ferguson Neil M , Donnelly Christl A , Grassly Nicholas C
Published: October 2021

Background

Phase III trials have estimated coronavirus disease 2019 (COVID-19) vaccine efficacy (VE) against symptomatic and asymptomatic infection. We explore the direction and magnitude of potential biases in these estimates and their implications for vaccine protection against infection and against disease in breakthrough infections.

Methods

We developed a mathematical model that accounts for natural and vaccine-induced immunity, changes in serostatus, and imperfect sensitivity and specificity of tests for infection and antibodies. We estimated expected biases in VE against symptomatic, asymptomatic, and any severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and against disease following infection for a range of vaccine characteristics and measurement approaches, and the likely overall biases for published trial results that included asymptomatic infections.

Results

VE against asymptomatic infection measured by polymerase chain reaction (PCR) or serology is expected to be low or negative for vaccines that prevent disease but not infection. VE against any infection is overestimated when asymptomatic infections are less likely to be detected than symptomatic infections and the vaccine protects against symptom development. A competing bias toward underestimation arises for estimates based on tests with imperfect specificity, especially when testing is performed frequently. Our model indicates considerable uncertainty in Oxford-AstraZeneca ChAdOx1 and Janssen Ad26.COV2.S VE against any infection, with slightly higher than published, bias-adjusted values of 59.0% (95% uncertainty interval [UI] 38.4–77.1) and 70.9% (95% UI 49.8–80.7), respectively.

Conclusions

Multiple biases are likely to influence COVID-19 VE estimates, potentially explaining the observed difference between ChAdOx1 and Ad26.COV2.S vaccines. These biases should be considered when interpreting both efficacy and effectiveness study results.
mRNA Vaccine-Elicited Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)–Specific T Cells Persist at 6 Months and Recognize the Delta Variant
Authors: Woldemeskel Bezawit A , Garliss Caroline C , Blankson Joel N
Published: October 2021

Little is known about the decay kinetics of coronavirus disease 2019 vaccine–elicited severe acute respiratory syndrome coronavirus 2–specific T cells. In this study we show a modest decline in the frequency of these T cells at 6 months and demonstrate robust expansion in response to antigen and recognition of spike peptides from the Delta variant.
Effect of nurse-led hospital-to-home transitional care interventions on mortality and psychosocial outcomes in adults with heart failure: a meta-analysis
Authors: Li Yuan , Fang Jinbo , Li Minlu , Luo Biru
Published: October 2021

Aims

To determine the effectiveness and dose–response of nurse-led hospital-to-home transitional care interventions (TCIs) on patient mortality and psychosocial outcomes of health-related quality of life (HRQoL), self-care behaviours, and emotional well-being in adults hospitalized with heart failure (HF) and to recognize pertinent characteristics that potentially affect the overall effectiveness.

Methods and results

Relevant studies were identified through electronic database searches, including MEDLINE, Embase, CINAHL, and Cochrane Library from January 2000 until January 2021. Two independent authors performed study selection, data abstraction, and risk-of-bias assessment. When appropriate, we used random-effects meta-analysis to derive pooled effect estimates, investigated dose–response relationships, and ran meta-regressions to locate the source of heterogeneity. A total of 27 studies with 7635 participants were included. Our findings revealed that nurse-led hospital-to-home TCIs reduced the risk of all-cause mortality by 21% [risk ratio = 0.79; 95% confidence interval (CI) 0.68–0.92; P = 0.003] and improved HRQoL (mean difference = −3.29; 95% CI −6.51 to −0.07; P = 0.04) compared to usual care, but non-significant effects were found for emotional well-being. The narrative summary of evidence for self-care behaviours showed positive intervention effects. Meta-regression did not find any covariates that were significantly related to mortality or HRQoL. Dose–response analysis showed that mortality risk was reduced with increased intensity and complexity of the nurse-led TCIs.

Conclusion

Generally, nurse-led hospital-to-home TCIs may play a beneficial role in decreasing mortality, and improving HRQoL and self-care behaviours for adults with HF. Additional studies are warranted to characterize the optimal nurse-led TCIs for HF management.
Dynamic tracing of sugar metabolism reveals the mechanisms of action of synthetic sugar analogs
Authors: van Scherpenzeel Monique , Conte Federica , Büll Christian , Ashikov Angel , Hermans Esther , Willems Anke , van Tol Walinka , Kragt Else , Noga Marek , Moret Ed E , Heise Torben , Langereis Jeroen D , Rossing Emiel , Zimmermann Michael , Rubio-Gozalbo M Estela , de Jonge Marien I , Adema Gosse J , Zamboni Nicola , Boltje Thomas , Lefeber Dirk J
Published: October 2021

Synthetic sugar analogs are widely applied in metabolic oligosaccharide engineering (MOE) and as novel drugs to interfere with glycoconjugate biosynthesis. However, mechanistic insights on their exact cellular metabolism over time are mostly lacking. We combined ion-pair ultrahigh performance liquid chromatography–triple quadrupole mass spectrometry mass spectrometry using tributyl- and triethylamine buffers for sensitive analysis of sugar metabolites in cells and organisms and identified low abundant nucleotide sugars, such as UDP-arabinose in human cell lines and CMP-sialic acid (CMP-NeuNAc) in Drosophila. Furthermore, MOE revealed that propargyloxycarbonyl (Poc)-labeled ManNPoc was metabolized to both CMP-NeuNPoc and UDP-GlcNPoc. Finally, time-course analysis of the effect of antitumor compound 3Fax-NeuNAc by incubation of B16-F10 melanoma cells with N-acetyl-D-[UL-13C6]glucosamine revealed full depletion of endogenous ManNAc 6-phosphate and CMP-NeuNAc within 24 h. Thus, dynamic tracing of sugar metabolic pathways provides a general approach to reveal time-dependent insights into the metabolism of synthetic sugars, which is important for the rational design of analogs with optimized effects.
Town Talk: enhancing the ‘eyes and ears’ of the colonial state in British Hong Kong, 1950s–1975
Authors: Mok Florence
Published: October 2021

This article offers a longer perspective on the origins and effectiveness of reforms of colonial governance in Hong Kong. It shows that the colonial state shifted from increasingly ineffective indirect rule to using a covert bureaucratic opinion poll, Town Talk, to assess public opinion. The article argues that this bureaucratic device increased the organizational capacity of the colonial state and, in so doing, enabled a constructed form of ‘public opinion’ to influence policy formulation in a state-controlled manner without democratization. This mechanism was used as an imperfect substitute for representative democracy. These reforms enhanced a ‘non-political’ sense of citizenship among the Hong Kong Chinese but failed to bridge a communication gap between an unelected government and the people over whom it ruled.
Anti-Severe Acute Respiratory Syndrome Coronavirus 2 Hyperimmune Immunoglobulin Demonstrates Potent Neutralization and Antibody-Dependent Cellular Cytotoxicity and Phagocytosis Through N and S Proteins
Authors: Díez José María , Romero Carolina , Cruz María , Vandeberg Peter , Merritt William Keither , Pradenas Edwards , Trinité Benjamin , Blanco Julià , Clotet Bonaventura , Willis Todd , Gajardo Rodrigo
Published: October 2021

Background

Although coronavirus disease 2019 (COVID-19) vaccinations have provided a significant reduction in infections, effective COVID-19 treatments remain an urgent need.

Methods

Functional characterization of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hyperimmune immunoglobulin (hIG) from human convalescent plasma was performed by different virus neutralization methodologies (plaque reduction, virus-induced cytotoxicity, median tissue culture infectious dose [TCID50] reduction, and immunofluorimetry) at different laboratories using geographically different SARS-CoV-2 isolates (USA [1], Italy [1], and Spain [2]; 2 containing the D614G mutation). Neutralization capacity against the original Wuhan SARS-CoV-2 strain and variants (D614G mutant, B.1.1.7, P.1, and B.1.351) was evaluated using a pseudovirus expressing the corresponding spike (S) protein. Antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) was also evaluated.

Results

All SARS-CoV-2 isolates were potently neutralized by hIG as shown by all 4 methodologies. Wild-type SARS-CoV-2 and variants were effectively neutralized using the pseudovirus. The hIG (IgG type) induced ADCC and ADCP against SARS-CoV-2 N and S proteins but not E protein. Very low concentrations (25–100 µg IgG/mL) were required. A potent effect was triggered by antibodies in hIG solutions against the SARS-CoV-2 S and N proteins.

Conclusions

Beyond neutralization, IgG Fc-dependent pathways may play a role in combatting SARS-CoV-2 infections using COVID-19 hIG. This could be especially relevant for the treatment of more neutralization-resistant SARS-CoV-2 variants.
Identifying regional environmental factors driving differences in climatic niche overlap inPeromyscusmice
Authors: Russell Vanessa L , Stevens M Henry H , Zeisler Addison A , Jezkova Tereza
Published: October 2021

Different groups of taxa exhibit varying degree of climatic niche conservatism or divergence due to evolutionary constraints imposed on taxa and distributional relationships among them. Herein, we explore to what extent regional environmental conditions that taxa occupy affect climatic niche overlap between pairs of congeneric species of Peromyscus mice exhibiting allopatric, parapatric, or sympatric distributions. We used Bayesian generalized linear mixed models to identify environmental variables that best explain differences in climatic niche overlap between species. Our results suggest that regional environmental conditions explain 13–44% of variation in climatic niche overlap. Specifically, allopatric and parapatric species pairs are more likely to occupy similar climatic niches in areas that are topographically less complex but with more complex habitats. Sympatric species are more likely to occupy similar climatic niches in areas that promote local niche partitioning (topographically less complex, warmer winter temperatures, higher precipitation, and higher habitat complexity on a local scale). By understanding the relationship between regional environmental conditions and niche overlap, we highlight how differences in geography can contribute to shaping niches of congeneric species.