bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enriching terpinen-4-ol from tea tree (Melaleuca alternifolia) oil using vacuum fractional distillation: Effect of column and packings on the separation
Authors: Le M T , Nguyen N M , Le X T 
Published: December 2021

Abstract
Two types of columns, three types of packings, and four levels of column height were considered to investigate how column and packings affected the separation in the vacuum fractional distillation process of raw tea tree (Melaleuca alternifolia) oil (TTO). This study discussed those effects on purity, yield, and overall discovery to select the most excellent operating conditions for enriching terpinen-4-ol. After the experiments, the essential oil was successfully separated into two fractions, in which the second one composed mostly the main TTO constituent, terpinen-4-ol. The best result was achieved by conducting the distillation on a 300-mm Hempel column filled with small Fenske helices (10 mm × 2 mm i.d.) at the system pressure of 60 mmHg. GC/MS analysis showed an almost 2.5-fold increase in the content of terpinen-4-ol, from 39.23% to 95.77% after fractionation. Meanwhile, there was 75% of terpinen-4-ol successfully recovered from its parental oil. Hence, the vacuum fraction distillation could be an effective method to enrich the terpinen-4-ol content in TTO.
Mathematical model simulation of the reaction process between 2,4,6-trinitrotoluen and hydroxyl radio in water environment
Authors: Nguyen Minh Tien , Le Anh Kien , Huynh Anh Kiet , Le Duc Trung 
Published: December 2021

Abstract
In this study, the author formulated the equation that describes the reaction rate (mathematical modelling) of 2,4,6-trinitrotoluen and hydroxyl radical (OH*) of v = 4.3×108×[CTNT]1.1×[COH*]3.2 and mathematical simulation for the reaction process of 2,4,6-trinitrotoluen and OH* radical. The simulation results showed a decrease in concentration [CTNT] and a reaction rate proportional to each other; during the first 0-30 minutes of the reaction, the reaction speed is very fast. From the experimental results, the authors also determined that the 2,4,6-trinitrotoluen treatment performance in wastewater of the nonthermal plasma model reached >99% when increasing the treatment time to 120 minutes.
A dynamic simulation of a styrene production process
Authors: Phuoc Pham Loi Hoang Huy , Le Duc Anh , Tran Vinh Quoc , Nguyen Tuan-Anh , Nguyen Trung Kim 
Published: December 2021

Abstract
Dynamic simulation plays a crucial role in process engineering, especially in designing control systems. As the interest in dynamic simulation for effective control and operation rises, the goal of the paper is to study and improve the dynamic performance of a styrene production process using simulation software to tackle various process design problems. The simulation process is carried out in four stages. In the first stage, flowsheet topology and process parameters are selected to meet the requirement of the main product. Control systems are designed for each piece of equipment in the process in the second stage. Both of the stages mentioned earlier are conducted in a steady-state environment. After finishing the second stage, steady-state simulation is complete. The third stage involves tuning control parameters of control loops in a dynamic environment. In the final stage, the performance of the system is tested by introducing disturbances in the form of pulse inputs. The results of the dynamic simulation illustrate that the control system is significantly influenced by the ethylbenzene feed flowrate disturbance. The production rate is heavily affected by the disturbance, while the production quality is assured. The average settling time of the process is 270 minutes.
Removal of aqueous organic pollutant by photo-Fenton process using low-cost Fe3O4/zeolite A
Authors: Quynh Ho Gia , Kiet Nguyen Anh , Thanh Huynh Van , Tue Ta Man , Truc Phuong Nguyen Thi , Long Nguyen Quang 
Published: December 2021

Abstract
Degradation of methylene blue (MB) in textile water treatment was investigated by using the photo - Fenton method (mixture of Fe2+ and H2O2 with the UV irradiation) in the presence of nano-sized and low-cost catalyst Fe3O4/Zeolite A. This catalyst was synthesized by impregnation method; furthermore, its photo – catalytic performances and durability in heterogeneous Fenton system were evaluated. Both the structure and the physical chemistry properties of the photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The study investigated the influences of different parameters of the MB decolorization efficiency such as initial concentration of peroxide attending the Fenton reaction, amounts of catalyst, pH of the dye solution and comparison of utilization of H2O2 in two cases with and without UV lamps. Under the optimum conditions which is the initial concentration of MB is 50 ppm and pH of dye solution is 3, high efficiencies of degradation were achieved – performance of 92.49%. These results suggest that the low-cost nanostructure catalyst Fe3O4/Zeolite A may be the considerable option because of the durability and the stability in the photo – Fenton reaction for organic wastewater treatment in textile industry.
Determination of Methylisothiazolinone and Methylchloroisothiazolinone in personal care products by HPLC-DAD
Authors: Pham Ngoc Thuy Vy , Hung Tran Viet , Thang Phan Nguyen Truong , Dang-Bao Trung , Anh Tran Thi Kieu 
Published: December 2021

Abstract
Preservatives are often utilized to prevent growth of bacteria and extend shell-life of personal care products (PCPs). This causes an increase in the number of cases of allergic contact dermatitis to preservatives. This study focused on the determination of two isothiazolinones (MI and MCI) in PCPs by HPLC-DAD. Different pretreatment methods were examined for different sample matrices. Recoveries were over 80% with %RSD < 6% in three studied sample matrices (wet tissue, shampoo and cream) at three different spiked levels. The method was applied to determine MI and MCI in 84 PCPs (shampoo, shower gel, cream, etc.) purchased in Ho Chi Minh City, Vietnam from March to July in 2021. MI and MCI were detected in some PCPs.
Synthesis and application of SBA-15-supported CuO as an efficient catalyst for the oxidative C(sp2)-O coupling reaction
Authors: Le Ha V. , Ho Khanh V. , Le Tu T. , Nguyen Vy T.B. , Le Huy X. , Nguyen Khoa D. 
Published: December 2021

Abstract
SBA-15-supported CuO was synthesized via wet impregnation of SBA-15 with copper (II) acetylacetonate followed by calcination in the static air. The BET surface area of the Cu-containing SBA-15 was approximately 600 m2/g, which significantly decreased in comparison with that of as-synthesized SBA-15 silica (1081 m2/g). The successful loading of copper with a 3.20 wt.% content was determined by ICP-OES analysis, consistent with theoretical composition. However, no Cu-based phases were detected on the PXRD results and TEM images for CuO/SBA-15 showed regular hexagonal meso channels remained, indicating that CuO species was well distributed in the SBA-15 framework via the applied synthetic procedure. Catalytic activity of SBA-15-supported CuO was investigated for the selective C(sp2)-O coupling reaction between salicylaldehyde and N, N-dimethylformamide (DMF) in the presence of di-tert butyl peroxide (DTBP) as an oxidant. Influence of the reaction conditions on the formation of desired product was studied including reaction time, temperature, reactant ratio, amount of catalyst and oxidant. The experimental results proved that the high activity of the prepared catalyst as the C(sp2)-O coupling product could be obtained in an excellent yield of 90% with only 3 mol% of SBA-15-supported CuO in the presence of 4 equivalents of DTBP at 120 °C in 2 hours.
Cloning and expression of the bacteriophage-derived endolysin against Aeromonas hydrophila
Authors: Loc Nguyen Tan , Huyen Bui Thanh , Hoang Hoang Anh , Nga Le Phi 
Published: December 2021

Abstract
Hemorrhagic septicemia disease in striped catfish is caused by Aeromonas hydrophila bacterium. Antibiotics are commonly used to treat this disease, however, due to antibiotic resistance in A. hydrophila, it is necessary to have an alternative antibacterial agent to antibiotics. Endolysins are bacteriophage-encoded peptidoglycan hydrolases that are synthesized at the end of the lytic phage replication cycle, they lyse the host bacterial cell wall and release new bacteriophage virions. In this study, an endolysin (cell wall hydrolase) derived from A. hydrophila phage PVN02 was artificially synthesized, cloned into pET28a(+) and successfully expressed in E. coli BL21 (DE3). The recombinant endolysin, cell wall hydrolase strongly exhibited antimicrobial activity against A. hydrophila with a reduction of 3-log CFU/ml of A. hydrophila after 30 minutes of mixing and further 30 minutes of incubation, the bacterial cells were lysed completely. It should be emphasized that the lytic activity by the recombinant endolysin to A. hydrophila bacteria did not require a pretreatment with an outer-membrane permeabilizer. The results of our study showed a potential of use this recombinant endolysin as a novel antibacterial agent to replace antibiotics in the treatment of hemorrhagic septicemia diseases in striped catfish.
Effects of different treatments of silver nanoparticles (AgNPs) on the growth & physiological characteristics of lotus (Nelumbo nucifera)
Authors: Vu Nguyen Quang Hoang , Hong Hoang Thi Kim , Quang Hoang Tan 
Published: December 2021

Abstract
Lotus (Nelumbo nucifera Gaertn.) is an aquatic perennial plant with various values, such as ornamental flowers, vegetables, food, and herbal medicine. It is cultivated and consumed throughout the different regions in Vietnam as a symbol associated with local culture. This study was conducted to evaluate the effects of four other treatments of silver nanoparticles (AgNPs) on the growth of lotus in crop 2021. In the present study, we examined the effects of 4 treatments: control - no AgNPs (CT), treating the soil with AgNPs 4mg/L 5 days before planting (T1), treating plants with AgNPs 4mg/L before planting (T2), and a combination of soil treatment, plant treatment, and periodic foliar application at 4mg/L (T3). The results show that AgNPs application by different methods significantly increased plant height, leaf diameter, fresh leaf weight, dry leaf weight, and some biochemical aspects compared with the control. Furthermore, exposure to AgNPs elevated the activities of peroxidase (POD), superoxide dismutase (SOD). Among the different of AgNPs applications, plants treated with T3 showed the highest efficiency. In addition, the chlorophyll content and diameter of floating and upright leaves were positively correlated with dry leaf mass. Thus, the current use of AgNPs in agricultural sciences offers the prospect of researching their impact on various plants in the future.
Roles of plant growth regulators on flowering of rose (Rosa hybrida L.’Red Rose’)
Authors: Hong Linh Tran Minh , Trinh Tu Cam , Bui Viet Trang , Tran Huong Thanh 
Published: December 2021

Abstract
Rose is the most popular ornamental flower all over the world, which is used as garden plants and cut flowers. In the case of Rosa hybrida L. ’Red Rose’, flowering provides the major developmental transition from the vegetative to the reproductive stage, and reproduction is one of the most important phases in an organism’s life cycle. In this study, the morphological and physiological changes during the flower development of rose, which is planted in the garden, and roles of plant growth regulators on the flowering of in vitro vegetative shoots of rose were analyzed. The development of a flower includes three stages: the shoot apical meristem, floral meristem, floral bud. Levels of cytokinin, auxins, and gibberellins increased in the transition of meristem from the shoot apical meristem to the floral meristem stage. Plant growth regulators have important effects on the shoot apical meristem cell division and flowering. The combination of 0.5 mg.L−1 GA3, 0.1 mg.L−1 NAA, 2.5 or 3.0 mg.L−1 BA to Murashige and Skoog (MS) medium induces the floral transition of the in vitro vegetative shoots with the highest percentage (41%) as well as growth and development in comparison to the other treatments after 10 weeks. Then, the in vitro floral meristem continuously developed into a flower bud after 12 weeks.
Aircraft hydraulic axial piston pump fundamental pulsation and simulation
Authors: Husnić Želimir , Dedić Remzo , Ustamujić Faris , Jelačić Zlata 
Published: December 2021

Abstract
The axial piston pump for aircraft hydraulics systems and other high pressure hydraulic system applications is presented. This paper discusses the pump’s pressure pulsation and the fundamental frequency. Pressure pulsation associated with single piston failure is explained in relation to its fundamental frequency. A predictive approach in maintenance and pump sub system health monitoring is proposed, using numerical modelling and applicable software.
Kinematics of steam film wetting while quenching cylindrical samples in thermal oils
Authors: Behrem Šefik , Hrnjica Bahrudin 
Published: December 2021

Abstract
The paper presents the determination of the velocity of the vapor front along the outer wall of a cylindrical specimen in the process of two-dimensional axisymmetric quenching of the samples in thermal oils. One thermal oil is Isorapid 277 HM heated to 40°C and the other thermal oil is Marquench 722 heated to 90°C. The experimental setup of the work consists of heating to a temperature of 850°C, then quenching three dimensionally different cylindrical probes. The dimensions of the probe were: ϕ25x100 ϕ50x150 and ϕ75x225 mm. All quenchings were done in strictly controlled conditions of the flow rate of the quenchant around the cylinder as well as maintaining the temperature of the quenchant within the maximum 40±2.5°C or 90d3°C, during the quenching of the samples. The velocity of movement of the steam front on the outer surface of the cylinder was determined from the time-measured values of temperatures at the marked points of each sample. The analysis of the steam front movement velocity along the cylinder wall starts from the moment the lower base of the probe touches the quenchant. During the process of immersing the test probe in the quenchant, in addition to measuring the temperatures in time, the time of lowering the probe to contact with the quenchant sample was also measured. The approximate average velocity of the vapor front was determined based on the indications of the lower and middle thermocouples located 1.5 mm below the outer surface of the cylinder wall. Based on the distance of one half the height of each probe and time, the velocity of the steam film movement or the kinematics of the steam film wetting was obtained. The obtained results were compared with the results of quenching in water and aqueous solutions of the same probes under the same strictly controlled conditions.
Assessment of integrity and remaining working life of welded steel structures
Authors: Bajramović Ermin , Islamović Fadil 
Published: December 2021

Abstract
Analyzing the period of exploitation of welded steel structures it can be concluded that they are predominantly exposed to the action of variable load. The welded joint as the largest stress concentrator due to the heterogeneity of structural, mechanical and operational properties is a key problem that is further complicated by the possible and realistically probable presence of crack-type faults. The assessment of integrity largely depends on a comprehensive analysis of the welded joint as the most critical place of welded steel structures. Integrity assessment is a necessary obligation for extending the working life, as well as revitalization, as a way to keep the structures in operation, despite the long period of exploitation. This paper presented an analysis of the process of fatigue crack initiation and growth, i.e. an assessment of the of the welded steel structures’ integrity and remaining service life under the influence of variable load.
Investigation of the influence of electrode manufacturers ‘recipes on the production and chemical composition of welding fume particles
Authors: Begić Razija 
Published: December 2021

Abstract
The quality of the welded joint, production and chemical composition of welding fume particles in the MMAW process, in addition to the welding parameters, mostly depend on the quality of the coated electrode. As part of the preliminary experimental research of the optimal technological composition of the electrode coating, from the aspect of minimizing welding fume, an experimental research of one class of electrodes, E 42 4 B 32 H5, EN 499/94, standard production program of three manufacturers of welding consumables. The test was performed to examine the influence of the manufacturer’s recipe on the production and chemical composition of welding fume particles.
Pressure stress modeling on expanded polystyrene materials using genetic programming
Authors: Bajramović Ermin , Hrnjica Bahrudin , Hasanagić Redžo , Bajramović Emir 
Published: December 2021

Abstract
In the production of expanded polystyrene, the standards are very high in terms of thermal, fire, dimensional, and mechanical characteristics, because each of the characteristics is a condition for achieving quality that allows competitiveness in the market. To ensure high-quality products, it is necessary to achieve optimal performance and product quality through carefully adjusted input parameters of production. Since the production of expanded polystyrene is specific in several ways, an experimental study was conducted in which the basic parameters affecting product quality were detected and through which a series of experiments were performed to prove product quality. Experimental research for this work was conducted on three types of expanded polystyrene samples whose purpose is to insulate floors exposed to pressure. The samples were made of the same material of different densities and aging times for which the pressure stress at a deformation of 10% was tested. After the experimental phase, the modeling of the output parameters was performed. Modeling involved the development of a model that describes a given problem and the obtained modeled values were analyzed and compared with the experimental one. The modeling method used genetic programming using the GPdotNET software package. The goal of modeling with the GpdotNET tool is to obtain a realistic model that would give the value of the compression stress at a deformation of 10% as an output variable in materials made of expanded polystyrene.
Measurement of welding fume production in welding with high-alloy electrodes
Authors: Begić Razija 
Published: December 2021

Abstract
Due to their good structural properties, stainless Cr-Ni steels have a very wide application in various branches of technology. During the welding of stainless Cr-Ni steels with high-alloy coated electrodes, welding fumes of complex chemical composition are generated, which is very harmful for welders and the environment. For the purposes of this experiment, two variants of one rutile Cr-Ni commercial electrode, designated E 23 12 2 LR 12, were designed and fabricated. Higher production of welding fume particles also means greater danger to humans and the environment. In order to show the influence of the base material on the production of welding fume particles, an experiment for measuring the production of welding fume particles was performed in which two different steels were used as the base material, general structural steel S235JRG2 and stainless steel X6CrNiTi18.10.
Analysis of the influence of condensation temperature and compressor efficiency on heat pump system efficiency
Authors: Koruga Nemanja , Dobrnjac Mirko , Golubović Dušan , Dobrnjac Nemanja 
Published: December 2021

Abstract
In heat pump cycles, heat is supplied to the working fluid from a certain group of low-temperature bodies and transferred to a group of high-temperature bodies, i.e. the heat source is at a lower temperature and the heat sink at a higher temperature. Using the method of circular processes, in synergy with the possibility of mutual conversion of thermal and mechanical interactions, the process of heat transfer from a lower temperature level to a higher temperature level is enabled. Mechanical work, which, as compensation, should be given by the environment to the system (working substance), is a difference between heat removed and heat supplied. The efficiency of the heat pump mostly depends on the temperature interval at which the process takes place, however, the efficiency of the heat pump is also affected by the thermodynamic parameters of its parts: compressor, condenser, throttle valve, and evaporator. In this paper, the influence of condensing temperature and compressor efficiency on the efficiency of the system as a whole is examined. The calculation was performed for two working substances, R123 and R134a, using the EES software package (Engineering Equation Solver) which is used for numerical modeling of thermodynamic systems, process optimization, and making process diagrams.
Concept design and design optimization of the transfemoral prosthetic leg prototype
Authors: Dedić Remzo , Ustamujić Faris , Jelačić Zlata , Husnić Želimir , Kvesić Vlado 
Published: December 2021

Abstract
The biggest challenge with today’s lower leg prosthetic devices is to climb the stairs in a biologically inspired way. When climbing the stairs, due to the large moments in the knee joint, great forces in the knee occur. Because of the magnitude of these forces, which can be up to six times the weight of a person, it is necessary to use a hydraulic drive with an external power source in the knee and ankle joint. However, most commercially available above-knee prosthetic legs only have actuation in the form of damping in the knee joint. Hence, an amputee is forced to use a healthy leg to advance to each step first while amputated leg follows.
Measurement analysis of braking forces and braking coefficient at different loads of a passenger vehicle
Authors: Halilagić Ramo , Hodžić Nedim 
Published: December 2021

Abstract
This paper presented an analysis of the braking force efficiency, i.e. its intensity in the case. It presented an analysis of the efficiency of braking forces, i.e. their intensity in the case when the load of a passenger vehicle was gradually changing. The change in the load of the vehicle was done by varying the number of passengers in it from one to five which is a feature of a higher number of M1 category vehicle. By increasing in the number of passengers the weight of the vehicle varied by approximately 75kg per passenger. The experimental test was performed in the technical inspection station, i.e. on standard rollers for the brake system testing. The test results shown that the relative difference of braking forces occurred on the front axle during intensive braking and that the braking coefficient was the lowest of about 69.94% in the case when only the driver was in the vehicle. It increased with increasing load, i.e. the number of passengers in the vehicle up to 85.91% and then dropped by increasing the rear passenger behind the driver and front passenger to 80.43% which can affect the stability of the vehicle when braking in the event of a dangerous traffic situation.