bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Spontaneous Combustion Tendency Grade of Sulfide Ore Based on Decision Tree Combined Classifier
Authors: Liu Nianping , Huang Siqi , Xie Xiaojun
Published: September 2019

Based on the related theories of decision tree and its classifier, a decision tree combiner model for spontaneous combustion of sulfide ores was established. Based on the analysis of the influencing factors of spontaneous combustion of sulfide ore, the three most representative measured characteristics, such as oxidation rate, self-hot spot, and auto-ignition point, were selected as predictors of the decision tree classifier model. Using the actual measured data of spontaneous combustion of sulfide ore as a training sample, a decision tree model for establishing spontaneous combustion of sulfide ores was used to predict the spontaneous combustion tendency grades, and verified with other measured data that did not participate in training. The results show that the decision tree combined classifier model is simple and feasible, with high prediction accuracy and simplified data processing. It is one of the effective methods to solve the problem of predicting the spontaneous combustion grade of sulfide ore.
Genetic algorithm approach for large scale quadratic programming of probabilistic supplier selection and inventory management problem
Authors: Sutrisno  , Widowati  , Sunarsih
Published: September 2019

This paper is focused on the effectiveness of existing metaheuristic optimization method, genetic algorithm (GA), in providing solutions to a large-scale integer quadratic programming of a probabilistic supplier selection and inventory management problem. The term “probabilistic” in this case refers to any problem that involves some uncertain parameters, approached by random variables (probabilistic parameter). We used the existing mathematical model of probabilistic supplier selection problem and inventory management provided in our previous works. This was done for optimization problem in a small-scale, which could be solved efficiently either by analytical or numerical method. We resolved this model with an extensive number of decision variable, indicated by the number of supplier and time period sufficient to use GA, conducted to analyse if the solution of decision variable, is reliable or not for application to the larger problem. We generated some random data to simulate the problem and the results, running over hundreds of computational experiments. The results showed that the decision obtained by the genetic algorithm was significantly different from the global optimal solution generated by the generalized reduced gradient (GRG) performed in LINGO 18.0. In conclusion, GA is not preferred in solving large-scale problems as regards supplier selection and inventory management.
The adsorption kinetics and isoterm of activated carbon from Water Hyacinth Leaves (Eichhornia crassipes) on Co(II)
Authors: Riyanto C A , Prabalaras E
Published: September 2019

Heavy metal waste can endanger human health and can accumulate in rivers or land. Heavy metals such as Co(II) can be removed or minimized using adsorbents such as activated carbon. The use of activated carbon from water hyacinth leaves (Eichhornia crassipes) has the potential to reduce the concentration of heavy metals in the environment as water hyacinth leaves (WHL) have the ability to adsorp both organic and inorganic compounds. This study aims to determine the appropriate adsorption kinetics and isotherm models in the process of Co(II) adsorption using activated carbon from water hyacinth leaves (ACWHL). The ACWHL can be produced from the carbonization process at 400°C for an hour and two-stage activation process (physical and chemical activation) with 30% H3PO4 as an activator and the impregnation ratio of 1:4 (w/w) for 24 hours and then activated at 600°C for 60 minutes. The analytical method used in this study was using a UV-Vis spectrophotometer. The results of the study showed that the ability of ACWHL to adsorp Co(II) followed the pseudo second-order kinetic model with R2 = 0.3086 and the Elovich isotherm with R2 = 0.664 with a maximum adsorption capacity of 140.725 mg/g. Fulfillment of this model can be assumed if the adsorption process of Co(II) on the surface of ACWHL occurs in multilayer.
Adsorption of cadmium using teak leaves powder (Tectona grandis sp.): embedding Mahaffy’s tetrahedral concept in undergraduate chemical engineering capstone lab project
Authors: Muryanto S , Firyanto R , Nurkholik
Published: September 2019

Chemical engineering education can be aptly structured on four central components: macroscopic, particulate, symbolic, and human element domains; known as the Mahaffy’s tetrahedral concept. This paper discusses the application of the concept of undergraduate chemical engineering capstone projects. The capstone was carried out as an undergraduate final laboratory project to investigate the adsorption of heavy metal, namely cadmium (Cd), using powder of teak leaves (Tectona grandis sp.). The lab experiment was environmentally safe, completed at ambient temperatures and that the experimental data collection was easy. It was actively guided by lecturers in a way to encourage meaningful lab experience as proposed in the Mahaffy’s tetrahedral idea. Three experimental variables were investigated: initial pH solution, adsorbent dosage, and initial concentration of Cd. The results were analyzed to determine the diffusion mechanism and kinetics through Weber-and-Morris intra-particle diffusion model. The experimental results agreed with most published literature which gave satisfaction on both students and lecturers. To assess learning outcomes, pre- and post-evaluations in regard the Mahaffy’s tetrahedral idea was employed. The post-test scores were significantly higher than those of the pre-test indicating that the learning outcomes were achieved. The lab project was also found to increase the student’s writing and presentation skills.
The effect of project based learning on learning environment and learning outcomes in vocational high school students
Authors: Rismawati  , Sunarno W , Sarwanto
Published: September 2019

The aimed of this study was to determine the effect of Project Based Learning Models on students’ learning environment and learning outcome in vocational High School. Samples were taken using cluster random sampling technique. This study used quasi-experimental method and involving a population of 142 students in the first year in automotive class from one of State Vocational High School in Surakarta. The sample was taken using cluster random sampling. Automotive class A with 36 students was used as the experimental class and automotive class B with 35 students as the control class. Data was collected using questionnaire, interview and test in the topic of rectilinear motion and circular motion. Data were analysed using descriptive and inferential analysis techniques using ANOVA. The results of this study showed that there was significant effect of project based learning model on students’ learning environment and outcomes. The project-based learning and learning environment has an interaction to determine the students learning outcome. Students tend to have better learning outcomes in good learning environment. Project-based learning successfully increases the learning environment significantly on indicators teacher-student relationships and Student-student relationships.
The Wayfinding Technology Application Dependability and its influential factors on Millennials
Authors: Jalil Emy Ezura A. , Ee Lim Kiong , Loo Wong Wai , Phok Yang Boon
Published: September 2019

The use of navigational applications is getting famous among riders. With the development of the internet, routes information is easily at the fingertips. From a fundamental perspective, routing could not be completed without navigational applications. The performance of navigational applications can be considered as one of the determinants that influence dependability on navigational applications. This paper presents the factors that influence the dependability of technology application in way-finding. In this study, three factors influence the dependability of navigational applications in way-finding which consists of social influence; accurateness and system reliability have been adopted. Using a quantitative approach via online survey design; about with 406 usable data derived from the population sample and they were identified to be dependent on navigational apps in their wayfinding needs. As a result, the findings indicated that all of the independent variables such as social influence, accurateness and system reliability have a significant relationship with dependability on navigational applications.
Kinetics Modelling of Batch Anaerobic Co-digestion of Domestic Primary Sewage Sludge and Food Waste in a Stirred Reactor
Authors: Mariam Sulaiman Siti , Seswoya Roslinda
Published: September 2019

Anaerobic digestion was conventionally applied for treating sewage sludge. However, the accumulation of solid waste particularly food waste has reach the critical levels worldwide. In practice, the food waste was dumped into the landfill for ultimate disposal. However, the greenhouse gases produced in the landfill makes this is no longer a preferable option. Anaerobic digestion was seen as an alternative for managing the food waste in a sustainable way. Methane, a renewable energy is potentially in replacing fossil fuel. However, the methane yield from the digestion of food waste inefficient. Therefore, a study of the co-digestion of sewage sludge and food waste was conducted to investigate the improvement of the methane yield. This study was conducted by using a mixture of domestic primary sewage sludge and food waste as a co-substrate for the anaerobic digester. The kinetics modified Gompertz modelling was applied to describe the anaerobic digestion process. A series of batch biochemical methane potential (BMP) assay was prepared using Automatic Methane Potential Test System (AMPTS II) to investigate the anaerobic digestibility of the mixture of domestic primary sewage sludge and food waste. The BMP assay showed that the co-digestion improved the ultimate methane yield by 32.6% higher than domestic primary sewage sludge alone, indicated that the co-substrate characteristics influencing the methane yield. Besides that, the greater VS/TS ratio of the substrate also resulted in the greater methane yield. The kinetics parameter from the modelling analysis were slightly lower as compared to the laboratory data.
Assessment of Cause and Effect Factors of Poor Communication in Construction Industry
Authors: Abdul Rahman Ismail , Gamil Yaser
Published: September 2019

Effective communication in construction industry is a core competency element to the success of the project. But it has been always a challenging mission to perform the communication effectively because the industry itself is characterized as fragmented, dynamic, and comprises of many parties (client, consultant, contractor, authorities) which leads to the presence of poor communication. There has been no publication to address the poor communication in a broad context especially identifying and assessing the causative factors and effects to this issue in the construction industry. However, this article aimed to identify and assess the significance of these factors through ranked them individually based on its level of significance/severity. Quantitative approach was adopted to conduct this study using structured questionnaire survey. A 5-point Likert’s type scale was used to assess the factors gradually based on their significance. Descriptive analysis was used to analyse the data collected from the survey. Average index (AI) and standard deviation were used to rank the importance of the factors in descending order. The study found that, the most dominant cause factors of poor communication is fear to communicate in the project space however the most dominant effect factor is high stress in workplace. The findings of this study serve best to draw a platform for construction practitioners to introduce strategies and plans to avoid the cause and diminish the effect of poor communication in construction industry.
Strategizing contractor firms to deliver green construction projects: conceptual framework
Authors: Powmya Ayisha , Zainul Abidin Nazirah , Sakina Mokhtar Azizi Nurul
Published: September 2019

Delivering green construction (GC) projects is not an easy task for inefficient or inexperienced contractor due to added requirements. This paper conceptualizes firm strategies in delivering green projects by focusing on enhancing firm resources. Journal articles with keywords such as ‘green construction’, ‘green project’, ‘sustainable construction’, ‘resources and capabilities’, ‘contractor strategies’, and so forth in the title, abstract or keywords of the publications were reviewed. Articles published from 2000 to 2018 in Scopus database were selected. The current literature on firm resources mainly focused on four assets (personal, financial, technological and organizational) and four capabilities (technical, innovative, managerial competency and collaborative). These assets and capabilities are necessary for contractor firms to survive in the industry. Capitalizing on these resources, this paper proposes seven strategies: human resource strategy, innovation strategy, financial strategy, smart collaboration strategy, environmental pro-activeness strategy, management enhancement strategy and information and communication strategy, for contractor to effectively deliver green project. Using Resource Based View (RBV) and Resource Mobilisation Theory (RMT), a conceptual framework is produced connecting firm resources and Resource Mobilisation Strategies (RMS). This paper shall benefit contractors and academician as it extended the knowledge on firms’ resources and recommend ways to strategize green delivery.
Experimental study on the out-of-plane strengthening of unreinforced masonry walls using cement-based fiber composites
Authors: Altoubat Salah , Maalej Mohamed , Leblouba Moussa , Saboor Karzad Abdul
Published: September 2019

This paper presents results from an ongoing research that is intended to study the behavior of URM walls for out-of-plane action. The effect of fiber reinforced shotcrete (FRS) as a strengthening method for the URM walls is examined. Eight URM walls were built inside a precast reinforced concrete boundary frame and strengthened with cement-based shotcrete mixes reinforced with different types of fibers. The masonry wall is 1.2x 1.2 m, and the masonry units were hollow concrete blocks (10 x 20 x 40 cm). Conventional fiber reinforced concrete (FRC) and engineered cementitious composite (ECC) were used as the strengthening layers sprayed on the surface of masonry walls. Control walls with plain shotcrete and conventional plastering mortar were also examined. Synthetic macro-fibers at dosage rate of 6 kg/m3 in FRC mix and Polyethylene micro-fibers at a dosage rate of 16 kg/m3 in ECC mix were considered in this study. The walls were placed in a carefully designed set up and tested under static central load using a hydraulic actuator with a capacity of 500 kN. The parameters recorded during testing were the applied load and out-of-plane displacement of the walls. Cracking pattern and failure modes were also monitored. The reported test results demonstrate that FRC and ECC mixes can significantly increase the out of plane strength and ductility of the URM walls.
How fair is construction business in Australia? Perception of Consultant Quantity Surveyors
Authors: Teck-Heng Lim Benson , Miu Rachel
Published: September 2019

Creating and managing a fair work environment is a crucial undertaking for management to increasing talent retention and improving organisational efficiency. Hitherto, little or no empirical study has done to investigate how construction employees perceive fairness at work and if their perceived fairness is positively associated with their emotion and pro-social behaviours. In addressing this gap, an online questionnaire survey was undertaken across 50 consultant quantity surveyors in the Australian construction industry to examine their perception of fairness at work and if their perceived fairness would associate with their emotion and behaviours. Overall, the findings suggest that there is a higher level of interpersonal fairness than distributive, procedural and information fairness in the Australian construction workplace. Furthermore, it is found that employees’ perceived interpersonal, informational and procedural fairness have strong positive correlations with their level of confidence, satisfaction, trust, harmony, enthusiasm and stress within the company, and that, in presence of a trusting, harmonious and active working relationship employees are very likely to adopt righteous, sportsmanship and courteous behaviours. In summary, the findings inform company management the types of perceived fairness that are associated with employees’ emotion and behaviours, and thus enable them to develop more targeted human resource management strategies to improve their organisational performance.
The selection of optimum water-cement ratio for production of low thermal conductivity cement sand brick with Oil Palm Mesocarp Fibre as admixture
Authors: Fatina Md Sali Nurul , Deraman Rafikullah
Published: September 2019

The development of housing construction project in Malaysia has rapidly increasing. However, the development of the projects only focusing on the exterior look without giving consideration on the thermal properties of materials used for building envelopes which may influence to external gain and thermal comfort for the occupants inside. As way to encounter the problem, one of the methods is by passive design which through utilized a low thermal conductivity of brick wall in creating good thermal insulation of the building envelops. This study investigated the characteristics of the cement sand brick (CSB) with incorporated of Oil Palm Mesocarp Fibre (OPMF) as admixture by using different water-cement ratio ranging from 0.45 to 0.65. All bricks were tested for compressive strength, water absorption and thermal conductivity. The result reveals that the higher water-cement ratio increased the compressive strength and water absorption, while decreased in thermal conductivity of bricks. It was found that, by incorporating of 0.65 water-cement ratio enhances the production of low thermal conductivity brick with value of 0.891 W/mºC, compressive strength of 12.4 MPa and water absorption of 1.99% that meets the standard requirement. Foremost, the incorporation of OPMF with water-cement ratio of 0.65 provides alternative solution for energy efficiency and improve the comfort in buildings by improving CSB insulation properties.
Analysis on Performance of Screw Compressor in MVR system
Authors: Liu Guangbin , Zhao Xiaoyan , Liansheng Li , Bin Tang , Qichao Yang , Yuanyang Zhao
Published: September 2019

Screw compressor is suitable for small scale mechanical vapor recompression (MVR) system especially for the solution with high boiling point elevation. In this paper, a mathematical model of screw compressor in MVR system is built and its working process is simulated. The results show that water injection improves the efficiency of screw compressor obviously and the compression process along saturated vapor line is realized if enough water is injected. The volumetric and isentropic efficiency is not sensitive with the water if more than flow rate of 35L/h is injected. The discharge temperature decreases from 133.4°C to 108°C with water quantities of 5L/h to 35L/h and then it is constant . The large saturated heat transfer difference in evaporator leads to decrement of volumetric efficiency but increment of isentropic efficiency. The mass flow rate of distilled water increase from 0.38t/h to 2.56 t/h and the saturated temperature difference increases from 4°C to 26.9°C when the rotating speed increases from 1000 rpm to 6000rpm.
Numerical analysis of gas-dynamic efficiency of the flow part of compact air heat exchangers and filters for mobile compressor units
Authors: Yusha V L , Filkin N Yu
Published: September 2019

The technique of numerical analysis of filters and heat exchangers used for air purification and cooling at mobile compressor units is presented. The proposed method is verified by comparing the results of numerical and experimental studies on similar objects in geometry and under similar operating conditions. The numerical parametric analysis of filters and heat exchangers with different options of the flow part is carried out. The efficiency of these devices has been improved by replacing the flat partition with a short diffuser with guides.
Optimization of sliding-vane expanders for a low-enthalpy ORC energy recovery system
Authors: Murgia Stefano , Valenti Gianluca , Costanzo Ida , Manfreda Pasquale Pio
Published: September 2019

Increasingly numerous are the experimental activities on low-grade ORC focused on expanders optimization, in order to increase the cycle net power and efficiency. In the range of small power ORCs, positive displacement expanders are more suitable than dynamic expanders thanks to lower speed, good off-design performance, high expansion ratio, low cost and simple manufacturing. This paper presents an extensive experimental analysis on a low-enthalpy ORC-based recovery system tested in different conditions: two different working fluids (R236fa and R1233zd) and two different sliding-vane expanders (ExpA and ExpB) are tested and the ORC performance are mapped in detail. A particular focus is dedicated to expander optimization: the operating conditions are deeply investigated by using piezoelectric pressure transducers to determine the expansion indicated diagram and the expander mechanical efficiency. Also the effect of the variation of both the expander and pump rotational speeds is investigated. The thermal source is the hot lubricant of a mid-size air compressor, the thermal sink is tap water.
Investigation into the effects of surface condensation in steam-driven twin screw expanders
Authors: Grieb Manuel , Brümmer Andreas
Published: September 2019

During the operation of twin screw expanders with slightly superheated vapours or even two-phase fluids, surface condensation on machine parts occurs during the filling period and the expansion phase when the working fluid is in contact with cooler inner surfaces. This heat exchange from the working fluid to adjacent machine parts effects the working cycle and the efficiency of these machines. Short time scales and the periodicity of the process indicate the condensation process is best described by models for dropwise condensation. In this paper the effects of surface condensation on the operation of twin screw expanders are initially discussed in a simulation-based investigation. Chamber model simulation coupled with a thermal analysis is used for the thermodynamic simulation, whereby heat transfer coefficients are systematically varied. It is found that during the inlet phase condensate emerges on the inner surfaces of the machine being substantially cooler than the working fluid. This results in a higher mass being trapped within the working chamber and, thus, an increasing mass flow rate of the machine. An increase in power output is, however, not observed. The results obtained from chamber model simulations are finally compared against experimental data of a screw expander prototype.
Creating a multi-level model of a centrifugal compressor for a digital analogue of the gas turbine engine
Authors: Marchukov Evgenii , Egorov Igor , Popov Grigorii , Baturin Oleg , Volkov Andrei , Kolmakova Daria
Published: September 2019

The paper presents the main ideas of the virtual test bench concept for rapid obtaining of the reliable characteristics of compressors based on a multi-level mathematical model with a two-step identification using data obtained from mathematical models with a high order of accuracy. One of the possible identification algorithms and the results of its successful testing are given on the example of a centrifugal compressor stage developed and tested at NASA.
Measurement of fluctuation at the discharge of positive displacement compressors
Authors: Rohleder C S , Groll E A
Published: September 2019

All positive displacement compressors (PDC’s) experience pressure fluctuation at the discharge ports of the compression mechanism, and these fluctuations can adversely affect compressor performance. These pressure fluctuations are caused by the nature of PDC’s; when a pocket of working fluid is exposed to system piping at differing pressure levels, a wave of pressure equalization flows through the line, potentially causing the compressor and piping to vibrate and generate noise (Soedel 2007). Compressor manufacturers currently use serial muffler designs, discharge plenums, and valves to minimize this fluctuation, but pressure fluctuation may persist at the outlet of serial muffling methods. A parallel muffling design has been developed for use in Roots blowers, having significantly reduced noise and pressure fluctuation seen in these machines (Huang et al. 2014). To identify the potential for use of this parallel muffling design in refrigeration systems and PDC’s, the magnitude of fluctuation at the discharge of a scroll compressor and a dual rotary compressor have been measured at various operating conditions. The compressors were left unmodified, with any current internal muffling methods in place. The measurement of these unmodified compressors determined the effectiveness of current muffling methods, with the intent to determine if using a parallel muffling technique is warranted. Pressure measurements were taken at 1000 Hz, and Fast Fourier Transform implemented to isolate pressure fluctuation based on frequency. Measurements lead to magnitudes of up to 16 kPa in pressure fluctuation with current muffling methods, indicating that further fluctuation reduction is possible.
A New Approach to Mechanical Loss Measurement of a Reciprocating Compressor
Authors: Kerpicci Husnu , Sahin Caglar , Ozdemir Ahmet Refik
Published: September 2019

Changing energy regulations urge all appliance manufacturers to use more efficient components in their products. Reciprocating compressor is one of the most crucial part for the energy efficiency of a refrigerator. Not only electrical and thermodynamic but also mechanical efficiency is the crucial issue determining the coefficient of performance (COP) of a compressor. Therefore, precise and trustworthy measurement comprising the frictional losses is one of the critical parameters to anticipate the real effect of novel design concepts. The objective of this study is the development of a new approach to measure mechanical losses of a reciprocating compressor. The method is based on the precise measurement of deceleration. A test rig, where the oil temperature, ambient pressure and temperature are able to be adjusted, is established. Measurements are performed under different average load for varying oil viscosity level. Load conditions are provided by adjusting ambient pressure of the chamber in which compressor body is placed. A heater is used on the body of the compressor to simulate temperatures corresponding with real temperatures acquired from the measurements of the compressor. Compression work is calculated by measurement of absolute cylinder pressure with respect to angular position of the crank shaft. Results are promising to use this measurement system for more detailed investigation.
Performance Testing of a Dual Rotary Compressor with a Variable Speed PSC Motor
Authors: Salts N P , Rohleder C , Groll E A , Chretien L , Yang B , Becerra R
Published: September 2019

A new system solution has been developed and tested by the authors and has been shown to improve the Seasonal Energy Efficiency Rating (SEER) of fixed-speed condenser split-system residential heat pumps. This is achieved through the use of a low power electronic drive that allows components with PSC motors (such as fans and compressors) to operate at multiple low speeds or variable speeds when partial capacity is required. At full capacity, the electronic drive is disabled and the PSC motors are operated at fixed speeds dictated by the frequency of the power source. Previous research by the authors has shown that fixed-speed heat pumps driven by rotary compressors with PSC motors achieve significantly greater improvements in performance and in overall SEER when operated with the electronic drive than similar heat pumps driven by scroll compressors with PSC motors. The current research measures the compressor and drive performance through calorimeter testing. This paper presents the results of testing a dual rotary PSC compressor in variable speed mode in association with the new electronic drive. The purpose of this testing is to understand how an off-the-shelf compressor with a PSC motor intended for fixed-speed operation performs under variable speed operation. Preliminary results of testing a PSC scroll compressor in variable speed mode with the electronic drive are also presented for comparison with the rotary compressor. Future research will focus on testing other common HVAC compressor technologies and employing mechanistic compressor models in order to better understand the parameters which affect the performance of PSC driven compressors under variable speed operation.
Efficiency analysis of the novel twin chamber rotary compressor
Authors: Na S K , Lee T M , Choi G M
Published: September 2019

The efficiency of the novel twin chamber rotary compressor was analyzed by comparing with conventional one. The increasing of the compression volume is the main advantage of the novel twin chamber compressor comparing with conventional one. To make this additional volume, newly geometric concept like vane bush was applied in the novel twin chamber rotary compressor. The losses occurred in these newly parts are different compared with the conventional one. So, the efficiency analysis of the novel rotary compressor was conducted about compressor loss aspect. To analyze these efficiencies, the simulation program was developed using numerical analysis. This program based on the conventional rotary compressor one. That means all the theoretical functions and concept of the conventional rotary compressor program was applied to novel compressor simulation program. To verify the numerical simulation method of the novel compressor program, experimental and simulation results were compared. Error between the simulation and experimental results were expressed in 4.2 to 8.6%. So, the simulation program showed a good agreement with experiments. Cooling capacity of the novel compressor is higher 34.68% compared conventional compressor. The input power of the novel rotary compressor is increased about 24.94% in ARI and 22.06% in CHEER conditions compared conventional one. Energy efficiency was evaluated with EER and the novel rotary compressor is improved about 8.06% in ARI and 10.76% in CHEER condition compared with conventional one.
Performance evaluation of a novel single-screw compressor and expander design
Authors: Ziviani Davide , Goeghegan Patrick J. , Groll Eckhard A.
Published: September 2019

Single-screw machines have seen significant development and improvement over the last decades and they are currently employed as both compressors and expanders in several applications. The correct functioning of the machine heavily relies on the meshing between the gate rotors and the central rotor which is directly linked to the precision of the manufacturing process to avoid unexpected wear of the tooth profiles. It is well known that the wear of the gate rotor tooth profiles over time is one of the limiting factors with respect to twin-screw machines. To this end, a number of studies have been reported in the literature about improved tooth profiles. For instance, the conventional straight-line profile has been replaced by multi-column tooth flank designs to enlarge the contact surface. However, the manufacturing process is still based on CNC machines with associated challenges.

In a previous study, the authors proposed and modeled a new tooth profile design to overcome the aforementioned limitations. In particular, 3D printing technique was utilized to manufacture the non-conventional tooth design. A geometry model has also been developed to calculate the sealing lines, groove volume curves, and surface areas of the new design.

In this work, a detailed mechanistic model of the single-screw machine is exercised to compare the conventional straight-line profile with the newly proposed tooth profile. Particular emphasis is given to the effect of seal lines on the leakage flows. Furthermore, the design implications of the new tooth profile on internal volume ratio, porting, and displacement are also discussed.
rnaSPAdes: a de novo transcriptome assembler and its application to RNA-Seq data
Authors: Bushmanova Elena , Antipov Dmitry , Lapidus Alla , Prjibelski Andrey D
Published: September 2019

Background

The possibility of generating large RNA-sequencing datasets has led to development of various reference-based and de novo transcriptome assemblers with their own strengths and limitations. While reference-based tools are widely used in various transcriptomic studies, their application is limited to the organisms with finished and well-annotated genomes. De novo transcriptome reconstruction from short reads remains an open challenging problem, which is complicated by the varying expression levels across different genes, alternative splicing, and paralogous genes.

Results

Herein we describe the novel transcriptome assembler rnaSPAdes, which has been developed on top of the SPAdes genome assembler and explores computational parallels between assembly of transcriptomes and single-cell genomes. We also present quality assessment reports for rnaSPAdes assemblies, compare it with modern transcriptome assembly tools using several evaluation approaches on various RNA-sequencing datasets, and briefly highlight strong and weak points of different assemblers.

Conclusions

Based on the performed comparison between different assembly methods, we infer that it is not possible to detect the absolute leader according to all quality metrics and all used datasets. However, rnaSPAdes typically outperforms other assemblers by such important property as the number of assembled genes and isoforms, and at the same time has higher accuracy statistics on average comparing to the closest competitors.
Nutrient digestibility of soybean products in grower-finisher pigs1
Authors: Yáñez Jorge L , Woyengo Tofuko A , Jha Rajesh , Van Kempen Theo A T G , Zijlstra Ruurd T
Published: September 2019

Solvent extraction of soybean creates soybean meal (SBM), but an array of other soybean products can be created using further processing of SBM or soybean. For accurate inclusion of these products in pig feed, characterization of digestible AA profile and energy value is required. Soybean products from processes such as extrusion (EX) of soybean and thermo-mechanical (TM) treatment, bioconversion using fermentation or enzymes (BC), and ethanol-water extraction (EW) of soybean meal were collected together with SBM. These 9 soybean products were tested in cornstarch-based diets together with an N-free diet for a total of 10 diets. Ten ileal-cannulated barrows (30.4 ± 0.7 kg initial BW) were fed 10 diets at 2.8 times maintenance DE for six 9-d periods with a 6 (periods) × 10 (pigs) Youden square. The control SBM contained 47.0% CP, 1.4% ether extract, and ADF 6.0%. The 9 soybean products contained 35.6% to 66.4% CP, 0.9% to 21.6% ether extract, and 4.4% to 8.0% ADF. The EW soybean products were high in CP (>61%), whereas the 2 EX soybean products were low in CP (<36%) but high in ether extract (≥19%). Chemically available Lys ranged from 92.6% to 100% of total Lys, indicating that minor Lys damage occurred during processing. The apparent total tract digestibility (ATTD) of energy was lower (P < 0.05) for soybean products with greater ether extract and ADF content than SBM, and varied among soybean products. The standardized ileal digestibility (SID) did not differ (P > 0.05) among soybean products for most AA, except for lower SID of Arg, Ile, Leu, Lys, Phe, and Tyr (P < 0.05) for EX2 and BC1 than other soybean products. The DE and predicted NE value did not differ (P > 0.05) among soybean products. The greater SID AA content (P < 0.05) in EW, BC, and TM1 soybean products than SBM was mainly a result of greater total AA content due to removal of other macronutrients. In conclusion, extrusion of soybean creates soybean products with a greater energy value but lower ATTD of energy and lower SID AA content than SBM. Further processing of SBM creates soybean products with greater CP and SID AA content but similar SID of AA than SBM. Thus, new technologies to process SBM or soybean create high-value ingredients to be included in pig diets, especially for young pigs with high nutritional requirements.
The Need for a National Strategy to Address Vector-Borne Disease Threats in the United States
Authors: Beard Charles B , Visser Susanna N , Petersen Lyle R
Published: September 2019

Vector-borne diseases (VBDs) cause significant morbidity and mortality each year in the United States. Over the last 14 yr, over 700,000 cases of diseases carried by ticks, mosquitoes, and fleas have been reported from U.S. states and territories to the Centers for Disease Control and Prevention. The number of reported cases has been increasing annually with two major trends: a steady increase in tick-borne diseases and increasing intermittent outbreaks of mosquito-borne arboviruses. The factors that are driving VBD introduction and emergence vary among diseases but are not likely to disappear, indicating that current trends will continue and probably worsen in the absence of effective prevention and control tools and implementation capacity. There are a number of challenges to preventing VBDs, including the lack of vaccines and effective vector control tools, insecticide resistance, and eroding technical capacities in public health entomology at federal, state, and local levels. For these reasons, a national strategy is needed to address VBD threats and to reverse the alarming trend in morbidity and mortality associated with these diseases.
rs11670527 Upstream of ZNF264 Associated with Body Mass Index in the Coriell Personalized Medicine Collaborative
Authors: Kusic Dara M , Roberts Wendy N , Jarvis Joseph P , Zhang Pan , Scheinfeldt Laura B , Rajula Kaveri D , Brenner Ruth , Dempsey Michael P , Zajic Stefan C
Published: September 2019

Introduction: the effects of obesity on health are a concern for the military as they affect the fitness to serve of active service members, increase costs to the Military Health System, and reduce quality of life for veterans and beneficiaries. Although obesity can be influenced by behavioral and environmental factors, it has also been shown to be associated with genetic risk factors that are not fully understood. Materials and Methods: we performed a genome-wide association study of 5,251 participants in the Coriell Personalized Medicine Collaborative, which includes 2,111 Air Force participants. We applied a generalized linear model, using principal component analysis to account for population structure, and analyzed single-variant associations with body mass index (BMI) as a continuous variable, using a Bonferroni-corrected P-value threshold to account for multiplicity. Results: we identified one genome-wide significant locus, rs11670527, upstream of the ZNF264 gene on chromosome 19, associated with BMI. Conclusions: the finding of an association between rs11670527 and BMI adds to the growing body of literature characterizing the complex genetics of obesity. These efforts may eventually inform personalized interventions aimed at achieving and maintaining healthy weight.
Effect of Pyrisoxazole on Colletotrichum scovillei Infection and Anthracnose on Chili
Authors: Gao Y. Y. , Li X. X. , He L. F. , Li B. X. , Mu W. , Liu F.
Published: September 2019

Anthracnose caused by Colletotrichum scovillei is one of the most destructive diseases affecting chili production. Disease control mainly relies on conventional fungicides, and repeated exposure to single-site mode-of-action fungicides may pose a risk for the development of resistant isolates within the population. Our previous study suggested that pyrisoxazole has strong inhibitory activity against C. scovillei in vitro. However, the effects of pyrisoxazole on the C. scovillei infection process and the performance of pyrisoxazole in the field remain unclear. In this study, pyrisoxazole exhibited strong inhibitory activity against the mycelial growth, appressorium formation, and appressorium diameter of C. scovillei, with half maximal effective concentration values of 0.1986, 0.0147, and 0.0269 μg/ml, respectively, but had no effect on sporulation, even at the highest concentration of 1.6 μg/ml. The baseline sensitivity curves were unimodal with a long right-hand tail. The in vivo data showed that pyrisoxazole provided both preventive and curative activity against anthracnose on chili. Pyrisoxazole decreased the incidence of anthracnose and reduced disease progress. The results of electron microscopy showed that pyrisoxazole can affect the C. scovillei infection process by altering mycelial morphology, degrading conidia and germ tubes, suppressing conidial germination and appressorium formation, and enhancing conidiophore production. Pyrisoxazole can be used to effectively control anthracnose under field conditions and increase chili yield; moreover, no phytotoxicity symptoms were observed after treatment. These results provide new insight into the mechanisms by which pyrisoxazole controls disease and suggest that pyrisoxazole is a feasible alternative for the management of anthracnose in chili.
Replicated Umbilical Cord Blood DNA Methylation Loci Associated with Gestational Age at Birth
Authors: York Timothy P. , Jackson-Cook Colleen , Moyer Sara , Roberson-Nay Roxann , Murphy Susan K. , Fuemmeler Bernard F. , Latendresse Shawn J. , Lapato Dana M. , Wolen Aaron R. , Do Elizabeth K. , Hoyo Catherine , Strauss Jerome F.
Published: September 2019

Background

DNA methylation is highly sensitive to in utero perturbations and has an established role in both embryonic development and regulation of gene expression. The fetal genetic component has been previously shown to contribute significantly to the timing of birth, yet little is known about the identity and behavior of individual genes.

Objectives

The aim of this study was to test the extent genome-wide DNA methylation levels in umbilical cord blood were associated with gestational age at birth (GA). Findings were validated in an independent sample and evidence for the regulation of gene expression was evaluated for cis gene relationships in matched specimens.

Results

Genome-wide DNA methylation, measured by the Illumina Infinium Human Methylation 450K BeadChip, was associated with GA for 2,372 CpG probes (5% false discovery rate) in both the Pregnancy, Race, Environment, Genes (PREG – Virginia Commonwealth University) and Newborn Epigenetic Study (NEST – Duke University) cohorts. Significant probes mapped to 1,640 characterized genes and an association with nearby gene expression measures obtained by the Affymetrix HG-133A microarray was found for 11 genes. Differentially methylated positions were enriched for actively transcribed and enhancer chromatin states, were predominately located outside of CpG islands, and mapped to genes enriched for inflammation and innate immunity ontologies. In both PREG and NEST, the first principal component derived from these probes explained approximately one-half (58.1% and 47.8%, respectively) of the variation in GA. This assessment provides a strong evidence to support the importance of DNAm change throughout the gestational time period.

Conclusions

These results converge on support for the role of variation in DNAm measures as an important genetic regulatory mechanism contributing to inter-individual differences in gestational age at birth. In particular, the pathways described are consistent with the well-known hypothesis of pathogen detection and response by the immune system to elicit premature labor as a consequence of unscheduled inflammation.
Homeostatic plasticity rules that compensate for cell size are susceptible to channel deletion
Authors: Gorur-Shandilya Srinivas , Marder Eve , O’Leary Timothy
Published: September 2019

Neurons can increase in size dramatically during growth. In many species neurons must preserve their intrinsic dynamics and physiological function across several length scales. For example, neurons in crustacean central pattern generators generate similar activity patterns despite multiple-fold increases in their size and changes in morphology. This scale invariance hints at regulation mechanisms that compensate for size changes by somehow altering membrane currents. Using conductance-based neuron models, we asked whether simple activity-dependent feedback can maintain intrinsic voltage dynamics in a neuron as its size is varied. Despite relying only on a single sensor that measures time-averaged intracellular calcium as a proxy for activity, we found that this regulation mechanism could regulate conductance densities of ion channels, and was robust to changes in the size of the neuron. By mapping changes in cell size onto perturbations in the space of conductance densities of all channels, we show how robustness to size change coexists with sensitivity to perturbations that alter the ratios of maximum conductances of different ion channel types. Our findings suggest that biological regulation that is optimized for coping with expected perturbations such as size changes will be vulnerable to other kinds of perturbations such as channel deletions.
Labeling Antibodies with Cy5-Phycoerythrin
Authors: Berg Eric A. , Fishman Jordan B.
Published: September 2019

Conjugates of the FRET dye Cy5-phycoerythrin (Cy5PE) with antibodies are relatively straightforward to make. The protocol does require synthesis of the Cy5PE tandem dye. Phycoerythrin (PE) can be purchased from multiple vendors. This type of conjugate is useful for immunofluorescence studies involving protein targets with low expression levels. Although the entire conjugation can be performed in a single day, there is an overnight stopping point. When initially making Cy5PE derivatives, several different conjugates with varying ratios of Cy5 to PE should be made. These should be tested by conjugating to a well-characterized antibody. Absorbance spectra readings are a very worthwhile step to determine the quality of the Cy5PE label.