bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of natural fiber tensile test apparatus using cantilever structure loading system
Authors: Abubakar  , Homma H , Ambarita H
Published: June 2020

Measurement of the mechanical properties of natural fiber is an important role in quality control. One of the most important mechanical properties of fiber is its tensile strength. To carry out tensile test fiber required tensile test apparatus. The tensile test apparatus used today is a foreign-made commercial tensile test imported at an exorbitant price. These conditions cause obstacles in the development of basic natural fiber technology in Indonesia. The purpose of this research is to design a natural fiber tensile test apparatus which is cheap and easy to operate. The result of this research is prototype of fiber tensile test which has been successfully tested with: 5N loading capacity, calibration curve accuracy: N = 1.052 V and loading rate 0.014 N/s. The result of tensile test to one natural fiber that used abaca fiber in range 100 MPa - 900 MPa and the data of tensile test results in existing literatures then there is conformity with the value of tensile strength. The results of this study are expected provide benefits for researchers, academics and industry in supporting the development of Indonesia natural fiber industry as well as enhancing competitiveness at international level.
The silica-filled polychloroprene rubber in the addition of alkanolamide: tensile and vulcanization properties
Authors: Surya I , Ginting M
Published: June 2020

Alkanolamide as a type of fatty alcohols was compounded to improve the tensile and vulcanization properties of silica filled polychloroprene rubber (CR) using a system of semi efficient vulcanization. The CR was filled by silica filler with a certain concentration at thirty phr and the alkanolamide was compounded within silica-reinforced CR at varied amounts i.e. 0.0, 1.0, 3.0, 5.0 and 7.0 phr. The results showed that alkanolamide increased the times to optimum cure, maximum and minimum torques and torque change. It also reduced the tensile moduli but increased the breaking elongations. The tensile strength was increased up to a three phr of alkanolamide incorporation and, the three phr of alkanolamide was an optimum concentration where silica filled CR vulcanizate with three phr of alkanolamide concentration had tensile strength with the highest value.
The properties of unfilled natural rubber in the existence of alkanolamide: swelling, mechanical and morphological properties
Authors: Surya I , Philbert
Published: June 2020

A study was carried out on the utilization of alkanolamide as a new curative additive in natural rubber (NR) compounds by using a semi-efficient vulcanization system. The alkanolamide was derived from the waste of cooking oil and incorporated into the unfilled-NR compound at 0.2, 0.4, 0.6, 0.8, and 1.0 phr. The effect of alkanolamide on swelling percentage, mechanical and morphological properties of the NR compounds were observed. It was found that the addition of the alkanolamide increased elongation at break of the NR compounds. The alkanolamide also increased tensile modulus, tensile strength, hardness and crosslink density of up to 0.6 phr of alkanolamide loading and then decreased with further increases in the alkanolamide loading. Scanning electron microscopy (SEM) micrographs proved that 0.6 phr loading of alkanolamide in the NR compounds exhibited the greatest matrix tearing line and surface roughness which correlated to a higher tensile strength of the NR compounds.
Quality control analysis to reduce defect product and increase production speed using lean six sigma method
Authors: Siregar Khawarita , Elvira
Published: June 2020

CV. Naga Mas engaged in manufacturing spare part. Support assy is one of the products that manufactured by the company. The product has an average disability percentage 9.49% of the total monthly production which exceeds the limits of the company. This study propose to increase production speed by to eliminate non value added activities and reduce the amount of disability products through design improvements. This problem solved with Lean Six Sigma approach with the combination Lean and Six Sigma concepts by using DMAIC steps to propose improvements through eliminate non value added activities and reduce the amount of defective products. Proposed improvements given that eliminate non value added activities and micro layout redesign settings. Based on estimates, the result for the process lead time reduction is 22.01 min / cycle process, increasing process efficiency and process cycle velocity, respectively for 7.80% and 0.0008 processes / h. Improvement plans are using 5S method such as sorting, arrangement, cleaning, consistency and self discipline that makes work programs in making machines, makes work procedures, inspects raw material, improves communication with suppliers and manages regular machine maintenance.
Optimization of Sei Mangkei special economic zone (sez) industrial land based on user needs
Authors: Widoyoko  , Nazaruddin  , Hidayati Juliza
Published: June 2020

Sei Mangkei Special Economic Zone (SEZ) is an industrial area with a total land area of 1,933.8 Ha, which is distributed into 18 (eighteen) zoning allotment areas. This industrial land zone has a 1 (one) type single plot, which is 1: 1 (200m x 200m) size or 4 hectares. With a single size pattern will result in high land residuals and cannot serve the needs of diverse users (markets) especially investors who need less than 4 (four) hectares of land. The pattern of size and variety of lots requires a redesign to be able to produce effective land use and provide optimal benefits for the company. In accordance with Permenperin No. 40 of 2016 that the pattern and size of industrial land is divided into 3 (three) sizes, i.e. plots of land ready to be built with small sizes ranging from 300 - 3,000 m2 per lot, medium size 3,000 - 30,000 m2 per lot and large sizes above 3 Ha per lot. The method of optimizing the size and variety of lots uses a model of dynamic programming and linear programming with the help of POM-QM software.
Identification of critical part in ripple mill repair design using quality function deployment method
Authors: Ginting Rosnani , Sawaluddin  , Fauzi Malik Alfin
Published: June 2020

At the company found problems related to the length of the product assembly process. The assembly system can be optimized by eliminating, combining, or simplifying the way the product is assembled so that the time needed in the assembly process becomes more minimum. If this design improvement is also carried out on other products produced by Jayatech Palmindo company, it will have a significant impact on reducing assembly time and unit costs in the production process. The integration of the Quality Function Deployment, Design for Manufacture and Assembly methods is expected to provide the right solution to improve the design of the ripple mill product and other products at Jayatech Palmindo company so that assembly time can be further shortened, and minimal unit costs without changing the value from the company’s products.
Determination of component categories using logic tree analysis
Authors: Rizkya I , Siregar I , Siregar K
Published: June 2020

Sterilizer machine plays important role in crude palm oil. Component machine has an important function to determine a maintenance based on the failure. Component failure is used to determine a correct maintenance. The problem faced by the company today is the high downtime of the sterilizer making machine causes the sterilizer production process to be disrupted. Machine breakdown around 35,66 hours/month. Machine failure analysis using the Failure Mode and Effect Analysis (FMEA) method and the Logic Tree Analysis (LTA) method. The LTA method used to determine priority to each failure mode and to review functions and malfunctions produce categories A (evident), B (safety), C (Economic Problem) and D (Hidden Failure) with the largest percentage for category B. The FMEA method analyse the factors causing component failure and its effect on overall system function by giving a Risk Priority Number value (RPN) based on severity, occurrence, and detection. The FMEA method produces the highest RPN values for 5 components namely IGBT, Mosfet, Bearing Bushing, Rool Former, and V-Block. LTA method shows that B Category has the largest percentage of component category. The result of this research is to categorize component failure and determine the Risk Priority Number for sterilizer machine.
Used tires recycle management and processing: a review
Authors: Haikal Sitepu Muhammad , Armayani  , Rahim Matondang Abdul , Tryana Sembiring Meilita
Published: June 2020

The number of used tires in the world is projected to increase in the future due to an incrementing number of cars and motorcycles particularly in developing countries such as Indonesia. This situation can endanger the environment and public health since it poses a high risk for fires. Despite the environmental impacts, used tires present economic values. This can be achieved by processing it into several forms such as tire-derived fuel, asphalt rubber, and rubber-plastic products. Furthermore, to collect used tires from tire users and send it into used tires recycler, management scheme is required. This paper aims to review the development of used tires recycle management and processing. It has been found that several management schemes for recycling used tires have been identified from literature including Extended Producer Responsibility (EPR), Free Market, and Government. Moreover, several processes to recycle used tires were identified, such as: retreading, energy recovery, product recycling, material recycling, and pyrolysis.
Quality control of crude palm oil (CPO) using define, measure, analyze, improve, control (DMAIC) and fuzzy failure mode and effect analysis
Authors: Siregar Khawarita , Ishak Aulia , Andi Sinaga Heru
Published: June 2020

In this case, the company Crude Palm Oil (CPO) is still not able to produce palm oil that meets the specifications that can be seen from the free fatty acid content reaches 3.51%. This can affect the quality of the products to be able to compete with a competitor. Therefore, this study aims to conduct quality control of Crude Palm Oil (CPO), to analyse the proportion of disability and ability in the production process, potential failures, to identify the root cause of the defect, and to calculate the value of the highest FRPN. The results of the study showed that the biggest problem faced by parts of machine settings and control machines that are not good due to less rigorous and disciplined operator in charge and has a value of FUZZY FMEA (FRPN) most high at 662.06 While the measurement results the sigma value of the company is 3,16. The results of the study showed that the biggest problem faced by parts of machine settings and control machines that are not good due to less rigorous and disciplined operator in charge and has a value of FUZZY FMEA (FRPN) most high at 662.06.
Design of warehousing system in order picking process: literature review
Authors: Melinda Tiara , Nazaruddin  , Ginting Rosnani
Published: June 2020

The warehouse is one part of a company that is holding an important role in the supply chain as a link between producers with the consumer. One of the most dominant activities in warehouse operations is the order picking process. This activity is very important because it directly affects consumer services. Even order picking generally spends around 55 % of total warehouse operating costs. The purpose of this paper is to build a framework that affects the order picking process using the Genetic Algorithm method. Some variables that influence the order picking process, especially the efficiency of order picking time include travel time, search time, pick time, setup time, number of workers and efficiency of workers. One of the causes of the high time of orders picking is the preparation of products that are not right in the warehouse. Genetic algorithms are used to find the best combination of product compilation. So that it is expected that improvements in the order picking process can improve warehouse efficiency.
The effect of fluxing material and method on the inclusion content of strontium modified A356.2 at Indonesia Asahan Aluminium Company
Authors: Kusriantoko Parindra
Published: June 2020

Aluminium foundry alloys are often contaminated with non-metallic inclusion particles in forms of oxides, carbides, and spinel. These inclusions can lead to significantly reduce of mechanical properties of aluminium foundry alloy. Fluxing treatment is one of the conventional methods for removing inclusions and oxides from the melt to enhance the quality of aluminium foundry alloy. In this study, we used several recipes of metal treatments and flux dosages and investigate the quality of A356.2. Filtration graphic by Prefil Footprinter and hydrogen content data by AlScan Hydrogen Analyzer were obtained to fully analyze the mechanism and get the best fluxing parameters.
Calculation of optimal raw material purchase costs using normalized goal programming method
Authors: Tambunan MM , Sinaga TS , Albert
Published: June 2020

Supplier selection is a very important activity to build an effective supply chain. The purchasing department is the department responsible for determining the number of raw material purchases from several suppliers. The purchase of optimal raw materials is done using normalized goal programming. Supplier selection criteria serve as targets to minimize the cost of purchasing raw materials, minimize reject of raw materials, and minimize delays in raw materials. From the results of the study obtained an optimal allocation of raw material orders and calculated the optimal cost of purchasing raw materials. Finally, order allocation by selecting the right supplier can reduce purchasing costs by 6.51% rice bran raw material, 4.85% yellow corn raw material, and 4.71% shrimp head flour raw material.
Comparison between client-side and server-side rendering in the web development
Authors: Fadhilah Iskandar Taufan , Lubis Muharman , Fabrianti Kusumasari Tien , Ridho Lubis Arif
Published: June 2020

Mandatory servers for universal applications that is accessible to number of users may be a deterrent for the corporation and excessive for small applications even though it could bring the compatibility advantages. Knowing that demand of web application increases to provide convenience and ease of use to the users, client side rendering comes to create software more fast and efficient. It has been done by redirecting the request towards an HTML file then the server will give messages without any content or a loading screen until the device takes all JavaScript to allow the browser compiling everything before displaying the content. Therefore, the purpose of this paper is to analyse the comparison between client side and server side method in the respect of technical aspects in term of first content paint, speed index, time to interactive, first meaningful paint, first idle CPU and estimated input latency that present better performance with 2.1s, 2.0s, 2.2s, 2.1s, 2.2s and 20ms respectively on server side. It also provide better result based on Google Audit with 100% performance, 48% accessibility, 93% best practice and 89% of search engine optimization (SEO).
Modelling analysis of service quality improvement in mobile communications based on hard handover
Authors: Pinem Maksum , Zulfin Muhammad
Published: June 2020

Mobile communication systems make it easy for users to be able to do the communication process even in a mobile condition, one of which allows users to move from a cell area coverage to another cell area coverage, this movement phenomenon is called a handoff. Handoff is the process of diverting traffic channels automatically on a mobile station (MS) that is being used to communicate without termination. This paper analyzes the service quality improvement of the hard handover mobile communication network model from two to three base stations (BS) on the path loss parameter. Service quality parameters to be considered are the improvement of signal degradation and delay handover from two BS to three BS against the fixed and adaptive hysteresis methods.
The effect of alumina on mechanical behavior of Al 6064 alloy
Authors: Kumar Abhishek , Kumar Paras , Singh R C
Published: June 2020

Need in the development of new materials with excellent properties are growing day by day. Composite materials are the simple and better way to accomplish materials with superior properties. Aluminium metal matrix composites due to their high strength to weight ratio, low cost, improved electrical conductivity and good tribological properties are broadly produced and used in various engineering applications in the area of automobile, aerospace and military engineering. In the present paper an attempt has been made to fabricate MMC of an alloy of aluminium 6064, reinforced with alumina particles through stir casting with vortex technique. Three aluminium alloy composites with alumina (2.5-5-7.5 wt. %) were fabricated. Different mechanical tests for hardness, tensile strength and toughness were carried out for the samples. Addition of alumina to aluminium alloy shows an increase in mechanical properties of aluminium metal matrix composite. The results showed that the stir casting could produce uniformly distributed reinforced particles of Al2O3 in Al 6064 alloy.
Simulation of CoFRP analytical and computational model for various fiber volume fraction and Investigation of the local stresses for different fiber orientation angle
Authors: Maheshwari Peeyush , Misra Anadi , Singh Ashtosh Kumar , Rawat Kamal Singh , Verma Ankur , Singhal Kavita
Published: June 2020

Present work provides a numerical tool for analyzing the variation of failure strength of Coir Fiber Reinforced Polymer (CoFRP) with respect to Fiber Volume Fraction (FVF) and Fiber Orientation Angle (FOA). A model has been developed for analyzing the failure strength of CoFRP. It is analyzed for various fiber orientation angle and fiber volume fraction. Failure strength of the CoFRP depends upon both FVF and FOA. In this analysis, it has been investigated that the analytical results for CoFRP lamina are very close to computational results. Finite element analysis scores over the experimental tests as it is more convenient and economical method of analysis. Therefore, this method is more suitable for future work.
Comparison of a Classical Cyclone Separator and Protruding Surface Cyclone Separator using CFD Software
Authors: Sati Vinay , Kaushik Shivasheesh , Kshetri Rahul , Panwar Kuldeep , Pandey Rahul
Published: June 2020

Industrial smoke contains various hazardous particles, ash namely to be one of the various substances. The cyclone separator is a specially designed device used to separate the ash particles from the stream of air. The stream of dirt and air mixture flows in two vortexes, the inner vortex and the outer vortex, this device in turns acts as a scrubber and the ash particles get collected down in the ash collector whereas the fresh air stream is released by the device. To increase the efficiency, i.e. to increase the ash collecting capacity of the device, we have tried to compare a classical cyclone separator with the one we created which has protruding surfaces internally and the comparative analysis is done using the CFD software ANSYS R16.0.
Synthesis and characterization of nanostructured DNA-templated polyimidazole nanowire
Authors: Yahaya M I
Published: June 2020

In this research work, nanostructured DNA-templated polyimidazole nanowires synthesized using simple and low-cost fabrication method that employed DNA as a template on which to carry out the polymerisation was reported. Their chemical properties were probed using different spectroscopic techniques (Ultra-Violet Visible (UV-vis) spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared (FTIR) spectroscopy). Atomic force (AFM) and electron microscopy (SEM and TEM) were used to characterize the nanowire dimensions. The techniques proved the formation of a supramolecular hybrid polymer containing DNA and imidazole polymers. The electrical property was measured using probe station. Morphological results exhibit different morphologies with agglomerate nanostructures for the diluted film, while dense rope like network of nanostructures were observed for undiluted templated polymers with diameter of 2-13 nm. Activation energy (Ea) including the uncertainty on it for the Plm/DNA bulk nanowires calculated was 10.6 ± 0.5 × 10−3 J mol−1 equivalents to 0.110 ±0.005 eV which is not surprising because the process is thermally assisted tunneling between localized sites.
2k Optimization approach for the removal of Pb2+ ions from water contaminated from oil-well drilling point on to MWCNTs
Authors: Gbajabiamila A T , Kariim I , Ighobesuo BO
Published: June 2020

The release of Pb2+ into the surrounding ecosystem has adverse effects on man and animal, hence, removing such harmful heavy metal from water system calls for urgent attention. The potential application of Multi-walled carbon nanotubes, MWCNTs, towards the lead (II) ions removal from oil polluted water body was studied and optimized via 2k factorial experimental approach. The MWCNTs produced was characterized via High Resolution Transmission Electron Microscope (HR-TEM), High Resolution Scanning Electron microscope (HR-SEM), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) and Brenuer-Emmette-Teller (BET) to determine the internal morphology, surface morphology, thermal stability, functional group and surface area respectively. The results of the HR-TEM depict the nano-structural diameter of the produced MWCNTs with continuous strands of tubes as depicted by SEM micrograph. The MWCNTs surface area produced was obtained to be 540 m2/g. The sorption of Pb2+ ions was optimized using 2k design approach where speed (rpm), absorbent dosage (g), temperature (°C) and time (min) were studied in a batch condition. The optimum conditions that give maximum sorption of Pb2+ ions on to the surfaces and the pores of the developed MWCNTs adsorbent were obtained at 60 min contact time, 59.89 °C, 0.20 g of adsorbent dosage and 599.98 rpm of agitation. Thus, the highest percentage sorption of Pb2+ ions by the MWCNTs from the oil-polluted water body was 99.5%. Hence, this study has demonstrated the potentials of MWCNTs as an effective and efficient sorbent for Pb2+ sorption from oil polluted wastewater.
Green synthesized silver nanoparticles for cream formulation: its anti-inflammatory and healing activities
Authors: Adeleye OA , Badru AO , Oyinloye OE , Fagbohun AB , Bakre LG , Bamiro OA , Babalola CO , Lateef A
Published: June 2020

Among several forms of metallic nanoparticles used in biomedical applications, AgNPs are the most fascinating and widely used. Therefore, this study was carried out to evaluate the antiinflammatory activity of Ehretia cymosa-AgNPs cream. Different extracts of the plant (methanol, ME; n-hexane, NE; ethylacetate, EE) were used to synthesize AgNPs, which were characterized by UV and FTIR spectroscopy. The AgNPs were used to prepare creams, and the physical properties of the creams were evaluated. Anti-inflammatory activities of the creams were evaluated by carrageenan induced rat paw edema method on albino rats. The biosynthesized AgNPs had UV absorption spectra in the range 400-450 nm. The creams had pH of 4.6-5.6 similar to the pH of the skin. Cream formulation NO (no extract) had no significant anti-inflammatory activity within 6 h of treatment while formulations NE, ME and EE had a significant anti-inflammatory activity within 6 h of treatment. The efficacy of the cream formulation of the extracts after 6 h of treatment was in the order EE > ME > NE. There was a significant anti-inflammatory activity with the AgNPs cream formulations. Formulations MS, NS and ES had 87.1, 90 and 100% anti-inflammatory activity, respectively in 4 h of treatment. The ES, MS and NS cream formulations had 100% healing in 4, 5 and 6 h, respectively, while only formulation EE had 100% healing in 6 h. Other cream formulations containing the extract could not achieve 100% healing in 6 h. The study established that Ehretia cymosa-synthesized AgNPs cream formulations had a faster healing ability compared with the positive control and Ehretia cymosa cream formulations.
Optimization of green synthesis of silver nanoparticles using Response Surface Method (RSM)
Authors: Ibrahim M , Agboola JB , Abdulkareem AS , Adedipe O , Tijani JO
Published: June 2020

This study is aimed at investigating the effect of synthesis parameters such as temperature, pH, volume of precursor and volume of extract on the crystal size of silver nanoparticles (AgNPs) synthesized via plant extract ofPiptadeniastrum africanum(African Oak) using 24factorial experimental design. The synthesized nanoparticles were characterized by X-ray Diffraction (XRD) and High Resolution Scanning Electron Spectroscopy (HRSEM) fitted with Energy Dispersive Spectroscopy (EDS). The optimum values of the synthesis parameters were found to be: pH 8, reaction temperature 35 °C, the ratio of the volume of extract to the volume of precursor was kept at 1:10 while silver nitrate (AgNO3)aqsolution was maintained at 1 mM concentration. The HRSEM and XRD analysis showed that the morphology of the nanoparticles is spherical with an average crystal size of 20-25 nm.
Preparation and characterization of nanosilica from sorghum husk ash by chemical method
Authors: Akaleme MC , Hassan IO , Olawuyi BJ
Published: June 2020

Extraction of nanosilica from Sorghum Husk Ash (SHA) was performed in this study by acid leaching method. Two methods of calcination was adopted (open and controlled method) in the production of SHA. Amorphous silica was produced by dissolving a quantity of SHA in hydrochloric acid solution which made the removal of heavy metals possible. The extracted/pure silica was rinsed with deionized water which lowers the pH to 7.0. The SHA silica was characterized using XRF, XRD and BET techniques. Silica and mineral contents of SHA were determined by XRF, while the X-ray diffraction patterns revealed the amorphous nature of extracted silica. Pure silica yield from SHA was 89.30%, while moisture content was 1.09%. The average particle size, BET surface area, pore volume, and pore diameter of SHA samples are 77.05 nm, 723.020 m2/g, 4.448e +01 cc/g, and 2.072e+00 nm respectively. The outcome of the research study reveals that the properties of the extracted silica satisfied all the requirements as established by relevant literature. Consequently, the high volume amorphous nanosilica with minimal mineral contaminants can be produced from SHA by the acid leaching method.
Thermophysical properties of nanoparticles in carboxylmethyl cellulose water mixture for heat enhancement applications
Authors: Akinpelu F O , Alabison R M , Olaleye O A
Published: June 2020

A successful drilling operation requires among others an effective drilling fluid which is also called drilling mud. Carboxylmethyl cellulose (CMC) which is a derivative of cellulose is commonly used because of its high viscosity. Its performance as a drilling fluid is limited at high temperatures and pressures due to its low thermal conductivity. A colloidal mixture of nanoparticles in CMC enhances the performance of the fluid. In this work, a comparison of the thermophysical properties of three metal oxides namely Titanium Oxide (TiO2), Aluminium oxide (Al2O3) and Copper Oxide (CuO) dispensed in Carboxylmethyl cellulose (CMC) water mixture in drilling operations were investigated at varying temperatures. Maximum of 0.4 volume fraction of the nanoparticles of each of the oxides in less or equal to 0.4 (≤ 0.4) of CMC concentration in water was considered. The governing equations obtained were simplified to a set of Ordinary Differential Equations which were solved numerically using Runge Kutta Scheme (order 4) along with shooting method. Results obtained showed that the metal oxides enhanced the heat transfer capability of the CMC water mixture. Besides, the conductivity enhancement is least with TiO2 in CMC water mixture and maximum with CuO in CMC water mixture. Viscosity and thermal conductivity increased with increasing volume fraction of the nanoparticles in the dispensing medium. These results were compared with existing literature and found to be in good agreement.
Setting time and standard consistency of Portland cement binders blended with rice husk ash, calcium carbide and metakaolin admixtures
Authors: Babako M , Apeh JA
Published: June 2020

The use of pozzolanic materials to reduce carbon dioxide (CO2) emissions and enhanced properties of mortar and concrete has received increased interests in the last decades. In this study, admixtures such as metakaolin (MK), rice husk ash (RHA) and calcium carbide waste (CCW) partially replaced Portland cement (PC) at 5, 10, 20 % in multiple combinations of aforementioned admixtures as binders and the effect of setting times (initial and final) and standard consistency on the binders were evaluated. The Department of Environment (DOE) approach for mix proportions was employed. The mixes are in six groups consisting of control PC, each admixture replaced PC at 5, 10 and 20 % replacement level in binary mixes, then two of the admixtures replaced PC at same replacement level in ternary and the three admixtures replaced PC in quaternary mixes respectively. Results indicated that RHA significantly influenced the standard consistency of the binders incorporating the three admixtures as compared with CCW and MK. The requirement of water in the binder increased with increase in percentage replacement level of RHA within the binder due to its porous nature. At 5 % replacement level, it was 9 % above control value, 21 % and 39 % at 10 and 20 % replacement level subsequently. Similarly, setting times at the aforementioned replacement levels are 27 % and 6 % above the control value for initial and final setting time. For 20 % replacement level, it was 24 % and 38 % above the control value for the initial and final setting time respectively. This is due to reduction in PC content leading to less content of Tricalcium silicate aluminate (C3A) and amount of carbon content within the pozzolanic materials which retard the rate of reactions. By and large, the admixtures retard the setting times of quaternary binder, and increased its water of consistency which can be overcome by activation. However, they are useful in the construction of concrete structural elements or structures that requires longer time for placement. Furthermore, it will be worthwhile to investigate same properties at the nanoscale since these have been established at the micro level.
Optimization studies on biosynthesis of iron nanoparticles using Rhizopus stolonifer
Authors: Adeleye TM , Kareem SO , Kekere-Ekun AA
Published: June 2020

Isolates from pure culture of Rhizopus stolonifer were aseptically grown in potato dextrose broth to early exponential phase and centrifuged. The biological synthesis of Iron nanoparticles from the fungus was carried out using simple techniques. Filtrates obtained by simple methods were reacted with 1 M Ferric chloride solution. Characterization of the synthesized iron nanoparticles was monitored using Ultraviolet-visible spectrophotometer and Fourier transform infrared spectroscopy (FTIR). An increase in synthesis of the iron nanoparticles by over 200% occurred when culture of selected isolate was agitated. At 325 nm, peaks of absorbance (3.5) were read at pH 4.5 and 6, while maximum production of the iron nanoparticles was reached at 35 °C. Peaks of transmittance of biosynthesized iron nanoparticles from selected isolate as shown by the FTIR spectrum were located at 750, 1100, 1700, 2500 and 3750 cm−1, representing the CH, C-O, C=O, SH and OH groups respectively. The varying degree of transmittance and pH reported presents the selected R. stolonifer isolate as a biological entity for the synthesis of stable iron nanoparticles.
Synthesis, bioactivities and cytogenotoxicity of animal fur-mediated silver nanoparticles
Authors: Akintayo G O , Lateef A , Azeez M A , Asafa T B , Oladipo I C , Badmus J A , Ojo S A , Elegbede J A , Gueguim-Kana E B , Beukes L S , Yekeen T A
Published: June 2020

Animal waste materials are rarely used in the synthesis of nanoparticles compared to microorganisms and plant materials. The use of animal fur (goat) in synthesis could assist in turning waste to wealth. Thus, potentials of animal fur in the synthesis of silver nanoparticles (AF-AgNPs), its biological activities and safety through cytogenotoxicity were investigated. Animal fur (1 g) was hydrolyzed with 100 ml of 0.1 M NaOH at 90 °C for 1 h, cooled and centrifuged at 4000 rpm for 30 min. The extract (1 ml) was added to 1 mM AgNO3 (40 ml) to reduce Ag+ to its nanoparticles. The AF-AgNPs was characterized using UV–vis spectroscopy, Fourier-transform-infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and Energy Dispersive X-ray (EDX) analysis. Larvicidal, antioxidant, anticoagulant and thrombolytic potentials of AF-AgNPs were studied. Onion bulbs (20) were exposed to 0.01, 0.10, 1.0, 10.0 and 100.0 μg/ml of AF-AgNPs solution for its cytogenotoxicity study with AgNO3 solution and distilled water as controls. Microscopic (24, 48 and 72 h) assessment of the onion cells and macroscopic (72 h) evaluation of the roots were also studied. The AF-AgNPs solution was brownish with surface plasmon resonance at 419 nm. Evaluation of FTIR spectra showed that protein molecules were used as capping and stabilization agents. The AF-AgNPs had size range of 11.67-31.47 nm, caused 60-100% mortality of exposed Anopheles mosquito larvae in 12 h, and scavenged DPPH (40-59%) and hydrogen peroxide (75-94%). The nanoparticles also exhibited anticoagulant and thrombolytic potentials on human blood with 25% lysis compared to 13% observed for only extract. Various chromosomal aberrations and growth inhibition were induced by AF-AgNPs especially at 72 h of 100 μg/ml. Extract from animal fur was explored in biogenic synthesis of nanoparticles and found to have high potentials as antioxidant, anticoagulant, thrombolytic agents. Inhibition of cell growth observed especially at highest concentration can be explored in anticancer drugs though with caution due to AF-AgNPs potential to induce chromosomal aberrations.
Nanotechnology in the built environment for sustainable development
Authors: Elegbede JA , Lateef A
Published: June 2020

Nanotechnology as an emerging discipline of the 21st century has immense benefits for mankind due to the exceptional attributes of nanomaterials which can be used to render novel products and services. Amongst several fields of human endeavours, the built environment, largely composed of the disciplines of construction engineering, architecture, fine and applied arts, and urban and regional planning can make use of nanomaterials in creating green facilities with improved properties, aesthetics and innovation. Though there are reports of basic and applied investigations dealing with the production and evaluation of nanomaterials in the built environment, there is still a gap in harnessing the information together for the benefits of the practitioners in the built environment. Therefore, this treatise serves to x-ray the applications of nanotechnology in the built environment with the view of establishing nexus between the two areas. This compendium may stimulate the re-engineering of curricula in the built environment and stimulates new lines of research, product development and evaluation.
Research on Vibration Suppression for AGARD Wing Based on State Space Model
Authors: Liu Xiaoyan
Published: June 2020

Based on the Observer method, the unsteady aerodynamic reduced order model is established. The aerodynamic, structural and control parts are in the form of state space equations. The state feedback control law is designed by linear quadratic regulator (LQR) method, and the active flutter suppression of aeroelastic system is realized. The three-dimensional AGARD elastic wing is selected as an example. The simulation results show that the active control law designed by the model reduction technique can effectively stabilize the response of the system, and the critical speed of closed-loop flutter increases greatly.
Analysis of Over-Torque Failure Characteristic of Tool Joints
Authors: Chen Feng , Zhu Wei , Qinfeng Di , Wang Wenchang , Wang Nan , Jin Yuguo
Published: June 2020

Increasingly demanding drilling conditions and progressive drilling technology put forward new requirements for the torsion performance of tool joints. Over-torque failure of tool joints in downhole occurs frequently, resulting in huge economic losses. It is of great significance to analyze the mechanism of over-torque failure of the tool joint. This mechanism can help to selection of the tool joint and improve the design of the tool joint. In this paper, three dimensional elastic-plastic finite element models of single-shoulder tool joint and double-shoulder tool joint are established. Based on ABAQUS, the stress characteristics of tool joints under working torque are analyzed, and the mechanism of over-torque failure of API single-shoulder tool joints and double-shoulder tool joints is revealed. The result shows that there is a serious stress concentration phenomenon in both single-shoulder tool joints and double-shoulder tool joints, which restricts the performance of tool joint. The stress distribution of the tool joint should be homogenized in the design of the new type of tool joint, so as to improve the performance of the tool joint.
Electronic properties of [111] hydrogen passivated Ge nanowires with surface substitutional lithium
Authors: Arellano L G , Salazar F , Trejo Baños A , Miranda A , Pérez L A , Cruz-Irisson M
Published: June 2020

In this work, a density functional theory study of the lithium (Li) effects on the properties of hydrogenated germanium nanowires (H-GeNWs) is developed. In particular, the electronic band structures, densities of states, formation energies, and Li binding energies of H-GeNWs grown along the [111] crystallographic direction with a diamond structure for different concentrations of surface substitutional Li atoms were studied. Ge nanowires with hexagonal cross sections and three different diameters were considered. The results indicate that all studied H-GeNWs maintain a semiconducting behaviour and the size of the energy band gap is a function of the diameter and the concentration of substitutional surface Li atoms. The formation energy analysis reveals than the energy stability of the nanowires increases when the nanowire diameter and the concentration of Li atoms augment. The results of this work give insight of how the electronic properties of H-GeNWs change during the charging process and open the possibility to incorporate them as electrodes in Li-ion batteries.
Effects of Transition Zone on Magnetic Properties of Low Temperature Oxidation of Magnetite Particle:Comparison of Experiment and Micromagnetic Modeling
Authors: Ge K , Williams W
Published: June 2020

A relationship of hysteresis parameters and oxidation of ultrafine magnetic particles on both experimental measurements and micromagnetic simulations is obtained through a step-by-step oxidation of magnetite. Numerical simulations of hysteresis loop and microstructure of a core-shell geometry with transition zone using a multi-layer structure show two categories of behaviour for magnetic grains during oxidation. First, the SD (Single Domain, <70 nm) and lager SV (Single Vortex, >130 nm) particles remain unchanged ratio of saturation remanence to saturation magnetization (M
rs/M
s), and slightly decreased coercivity (B
c) during oxidation. Second, the fine SV particles (80 nm to 120 nm), the hysteresis parameters respectively increase and dramatic decrease at the early and late stage of oxidation, and the micromagnetic behaviors vary significantly. Finally the hysteresis parameters of larger SV particles remain nearly unchanged during oxidation. The predicted magnetic properties for the core-shell model exhibit better agreement with experimental data than that of previously used core-shell geometry (a stoichiometric core surrounded by an oxidized shell). It indicates that the magnetic properties of partially oxidized magnetic grains are controlled by the multi-layer coupling effects and can record paleomagnetic signals.
Reflection spectra of a thin-film GeSbTe diffraction grating on a silicon nitride waveguide
Authors: Minnullin R T , Sapegin A A , Makarov M E , Korolev D S , Yu Barabanenkov M
Published: June 2020

Recent advances in nanophotonics are due to the implication of new approaches to the photonic devices and components design, not only related to structural features, such as subwavelength periodic arrangements, but also new materials, e.g., phase-change materials like GeSbTe (GST) alloys. We consider recently proposed optical non-volatile GST memory cell with a GST diffraction grating instead of a continuous film placed on a silicon nitride waveguide. The grating allows diminishing the energy budget of an incident electromagnetic beam in case of an optically induced phase transition of GST due to excitation of the resonant guided mode in the grating. The excitation of this mode results in anomalous reflectance spectra of the waveguide-grating structure. Here, we present the reflection spectra of GST diffraction gratings on a silicon nitride waveguide calculated with the use of the matrix Riccati equation technique in the theory of multiple electromagnetic wave scattering in inhomogeneous media. We show how the reflection changes with variation of different parameters – grating period and height, incident wave polarization, and phase of the GST film.
Self-dual cuspidal representations
Authors: Adler Jeffrey , Mishra Manish
Published: June 2020

Let

G
G

be a connected reductive group over a finite field

f

\mathfrak {f}

of order

q
q

. When

q
≤
5

q\leq 5

, we make further assumptions on

G
G

. Then we determine precisely when

G
(

f

)

G(\mathfrak {f})

admits irreducible, cuspidal representations that are self-dual, of Deligne-Lusztig type, or both. Finally, we outline some consequences for the existence of self-dual supercuspidal representations of reductive

p
p

-adic groups.
Another 𝑆-unit variant of Diophantine tuples
Authors: Fuchs Clemens , Heintze Sebastian
Published: June 2020

We show that there are only finitely many triples of integers

0
>
a
>
b
>
c

0 > a > b > c

such that the product of any two of them is the value of a given polynomial with integer coefficients evaluated at an

S
S

-unit that is also a positive integer. The proof is based on a result of Corvaja and Zannier and thus is ultimately a consequence of the Schmidt subspace theorem.
Segal spaces, spans, and semicategories
Authors: Haugseng Rune
Published: June 2020

We show that Segal spaces, and more generally category objects in an

∞
\infty

-category

C

\mathcal {C}

, can be identified with associative algebras in the double

∞
\infty

-category of spans in

C

\mathcal {C}

. We use this observation to prove that “having identities” is a property of a non-unital

(
∞
,
n
)

(\infty ,n)

-category.
Early Modern Regional Drama
Authors: Woodcock Matthew
Published: June 2020

Early modern regional drama produced in England between the Reformation and the closure of the public theaters in 1642 can be divided into three categories: provincial performances by touring playing companies; entertainments and masques staged by civic, ecclesiastical, and aristocratic hosts during Tudor and Stuart royal progresses; and drama produced by towns, cities, and communities themselves. There are also many instances of performances where these three categories overlap or interact. Touring companies under royal or noble patrons performed in a variety of locations upon visiting settlements in the provinces: in guildhalls, inn, churches and churchyards, open spaces, noble or gentry households, or, on a few occasions, purpose-built regional playhouses. There is extensive evidence of touring companies playing in the provinces across England and Wales until the 1620s, although there were fewer opportunities for patronized touring companies under the Stuarts and greater incentives and rewards for performing in London and (from 1608) in the new indoor theaters. Drama also came to the provinces during Tudor and Stuart royal progresses in the form of shows and masques staged in urban communities, elite domestic houses, and at the universities of Oxford and Cambridge. The heyday of such entertainments was during Elizabeth I’s reign; between 1559 and 1602 the queen visited over 400 individual and civic hosts. The reigns of James I and Charles I saw far fewer progresses into the provinces and the principal focus of Stuart royal spectacle was court masque and London’s Lord Mayor’s shows. Nevertheless, the monarch and royal family were entertained around the country from the 1620s until the 1630s, and Ben Jonson played a key role in scripting some of the provincial masques staged. Early modern regional drama also took the form of civic- and parish-based biblical plays and pageants that continued medieval guild-based performance traditions. Drama was also performed in provincial schools and in the universities, as well as in private households, throughout the period. Examining early modern drama from a regional perspective, and identifying how, where, and why drama was performed across the country, enables the construction of a broader and more complex understanding of theater and performance as a whole in the 16th and 17th centuries. When it comes to reflecting the wider social, geographical, and gender demographics of early modern England, regional drama is shown to offer a more truly representative, inclusive conception of national drama in this period than that which is predicated on London-based material alone.
Leadership for School Desegregation
Authors: Lindsey Randall B. , Lindsey Delores B. , Terrell Raymond D.
Published: June 2020

School desegregation efforts begun in the 1960s through to the 1980s persist into the 21st century. School leadership for desegregation began in the late 20th century. School leadership efforts began in the early 1960s with compliance-based responses focused on court-ordered and government directives in pursuit of equality with an eye to societal integration.

Leadership for desegregation is a legal response to de jure and de facto segregation as practiced in social, political, and economic systems throughout U.S. history. Efforts at more equal opportunities for historically marginalized students have, over time, evolved into an equity focus that holds a value for educating children and youth whether in integrated settings or not. By the turn of the 21st century, leadership efforts for equity began to recognize the need to provide access and opportunity to all students in all settings.

Four distinct chronological periods of school desegregation have evolved: desegregation leadership experiences, 1950s–1970s—mandated, minimum compliance; school desegregation leadership experiences, 1970s–1990s—supported by Emergency School Aid Act; school desegregation leadership experiences, 1990s–2015—Emergency School Aid Act and resegregation; and school desegregation experiences, 2015 to the present and predictable future.