Regression Equations to Determine the Stages of Electric Current in Electrical Discharge Machining (EDM) According to the Level of Desired Surface Roughness with Shortest Processing Time

Electrical Discharge Machining (EDM) is one of the most common non-conventional machining processes used in the manufacturing of die and mold. In the process of EDM, practitioners usually face a problem, which is how to shorten process time and determine the point where the current should be changed so that the resulted surface roughness is not too high due to the use of large current at the beginning of the process. The purpose of this study is to determine the point when to change (reduce) the current in order to obtain the desired surface roughness and shortest processing time. From analysis of data, experiment was obtained some regression equations, those are: average surface roughness (Ra = 5424 + 0.698 I) which is used to find the final current to obtain the desired final surface roughness, peaks to valleys average roughness (Rz = 5.73 + 3.418 I) which is used to find the changing point for initial current and duration of processing time (t =103.164 + 0.4714 I) which is used to estimate the duration of processing time with the input of initial and final currents

Studi Optimasi Fraksinasi Amonium Sulfat Pada Percobaan Isolasi Pada Glukosil Transferase Dari Kultur Suspensi Sel Solanum Laciniatum

Kultur suspcnsi sci Solanum laciniatum telah dikctahui dapal mclakukan reaksi biotransformasi terhadap PABA menjadi PABA-glukosida (P-D-glukose-l-p-aminobcllzoate) dan telah dilakukan ekstraksi gubal enzim sehingga diperolch aktivitas enzim PABA-glukosiltransferase namun hasilnya belum optimum, maka pad a pcrcobaan ini dilakukan optimasi fraksinasi ammonium sulfat sehingga didapatkan enzim P ABA-glukosiltransferase dengan aktivitas terbesar. Produk glikosida PABA dapat dihasilkan secara in vitro melalui proses penambahan enzirn langsung secara bebas dari luar. Oleh sebab itu, glukosiltransferase pada kultur sel Solanum laciniatum mempunyai peran penting, karena ketcrlibatannya scbagai katalisator dalam upaya modifikasi molekul senyawa PABA menjadi senyawa glikosidanya yang mudah larut dalam air, sehingga mempunyai nilai tambah pada proses terapeutik. Tujuan dari penelitian ini untuk mengetahui pada fraksi (NH4)2S04 keberapakah mampu mengendapkan PABA-glukosiltransferase sehingga enzim ini mempunyai aktivitas paling besar dan mengetahui pada hari keberapakah sel-sel kuhur Solallum 'adnia/um menghasilkall PABA-glukosiltrallsfcrase dengan aktivitas terbesa

Controlled synthesis of layered double hydroxide compounds with novel morphologies for biological applications

The research work presented in this thesis focuses on the synthesis and characterization of drug containing layered double hydroxides (LDHs), a group of anionic clays, with novel properties. Owing to their flexibility in accommodating anionic compounds in their interlayer galleries, they are potential for developing materials with a wide range of applications. In particular, LDH intercalated with organic anions, named as organo-LDH, is one of the most important organic-inorganic hybrid materials that have recently attracted considerable attention in pharmaceutical field. The main research work is to prepare drug-containing LDHs with novel structures and properties. First, we present the work on producing ibuprofen intercalated LDH nanocrystals with different particle size and morphology under different synthesis conditions including solvent type, and aging conditions in chapter 4. As a result, they further affect inter particle interactions that give different aggregation states in the dry powders. It was found that the relatively oriented dense powder through preferential face-to-face and edge-to-edge aggregation of LDH nanoparticels results in a considerably slower release rate of ibuprofen compared with that from the loose ones.DOCTOR OF PHILOSOPHY (SCBE

Noncatalytic and catalytic oxidation of organic pollutants in wastewater by air

With the ever-increasing worldwide population and demand for various goods andcommodities, rapid economic development gives rise to increasing volume of wastewa-ter globally produced by various industrial sectors, such as chemical, pharmaceutical,petrochemical, food, oil refineries, dyes and textiles, and agricultural activities. Conse-quently, they pose a greater challenge to theenvironmental remediation and protection,which calls for more effective and efficient technology for the wastewater treatment inorder to meet more stringent discharge standards. Among different types of pollutantsgenerated by industry, organic wastes account for the majority, which often containhighly toxic and hazardous compounds, such as aromatic and phenolic hydrocarbons,chlorinated and halogenated solvents, organic dyes and azo derivatives, pesticides, her-bicides, and antibiotics. Each of these organic pollutant families requires specificelimination methods, which should be judiciously selected to obtain minimum traces ofresidual organic contents as the main criterion.Published versio

PROTOTYPE SISTEM PENDATAAN KELUAR-MASUK KENDARAAN PADA KLUSTER DENGAN MENGGUNAKAN RFID UHF

PROTOTYPE SISTEM PENDATAAN KELUAR-MASUK KENDARAAN PADA KLUSTER DENGAN MENGGUNAKAN RFID UHF - RFID UHF, Kluster, Sistem Pendataan Kendaraa

The diversity of Salmonella serovar isolates originating from Indonesia

[no abstract available

Augmented reality application for chemical engineering unit operations

Understanding unit operations is an essential part in chemical engineering course. An important example is the continuous distillation column, which operation is often seen as a black box, where the incoming feed will undergo separation process inside the column to produce desired products. Despite having learned the concepts on how they work, students may find it difficult to comprehend and visualize what is going on inside a distillation column and how to connect various theories involved in the design and calculations. By developing a virtual visualization tool, such as augmented reality (AR), students can better visualize the process, such as fluid flow profiles and different components that make up a distillation column. Although the idea of incorporating AR for higher education learning is not entirely new, this is the first initiative to implement virtual technology for chemical engineering curriculum in Singapore, which serves as a novel pedagogical approach to complement the conventional pen-and-paper teaching method. Besides enhancing the students’ learning experience, it is believed that the AR application would provide a way to improve the students’ motivation and interest to learn the subject as well as a complementary tool for laboratory demonstration, as it is practically safe and time-saving

Cefalexin-immobilized multi-walled carbon nanotubes show strong antimicrobial and anti-adhesion properties

Multi-walled carbon nanotubes (MWNTs) possess weak antimicrobial property. In this report, we demonstrate that the covalent immobilization of the antibiotic cefalexin via poly(ethylene glycol) as a linking agent improves the antimicrobial and anti-adhesive properties of MWNTs against both Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). In particular, the MWNT-cefalexin composite showed 2-fold higher antimicrobial property than pristine MWNTs against S. aureus and B. subtilis. Moreover, the MWNT-cefalexin deposited film effectively inhibited cell adhesion. Given the simple, inexpensive procedures of our synthesis method, the MWNT-cefalexin composite has the potential to be used as an effective and economical antibacterial and anti-adhesion material for environmental and biomedical applications

Sodium Hydroxide Treatment for Cellulose Fiber Accessibility from Corncobs under Microwave Assistive

Corncob is abundantly available lignocellulosic biomass resources obtained from crops harvesting and found to be solid waste accumulation on a field. Less corncob is used as a solid fuel for cooking, and a more significant portion is vanished on the field by burning. Promisingly, corncob contains considerable cellulose as one value-added component potentially utilized as biomaterial or biofuel feedstock. However, the presence of lignin in natural lignocellulosic biomass results in recalcitrant structure and hinders cellulose accessibility. This study aimed to investigate microwave-assisted alkaline treatment to retain cellulose in the solid product while removing other impurities in corncob, especially hemicellulose and lignin. Sodium hydroxide was selected as a chemical with some variations in concentration. The chemical treatment was carried out under 400 W microwave power with various residence times and a 1:10 solid to liquor ratio. The cellulose content upgraded from 26.97% to 71.26% while reducing hemicellulose and lignin from 38.49% to 18.15% and 19.28% to 6.4%, respectively, on chemical treatment using 8% sodium hydroxide concentration for 20 minutes residence time. Scanning electron microscope (SEM) and Fourier transform infrared (FTIR) analysis also confirmed the results. The treated corncob also increased its crystallinity from 30.11% to 52.91%

Silver nanoparticles deposited layered double hydroxide nanoporous coatings with excellent antimicrobial activities

Simple and facile processes to produce silver nanoparticles deposited layered double hydroxide (Ag-LDH) coatings are reported. High quality nanoporous LDH coatings are obtained under hydrothermal conditions via an improved in situ growth method by immersing the substrates in LDH suspensions after removal of free electrolytes. Different types of substrates including metal, ceramics, and glass with planar and non-planar surfaces can all be coated with the oriented LDH films with strong adhesion. The pore size can be easily tuned by changing the metal:NaOH ratio during the precipiation process of LDH precursors. In the presence of LDH coatings, silver ions can be readily reduced to metallic silver nanoparticles (Ag NPs) in aqueous solutions. The resulting Ag NPs are incorporated evenly on LDH surface. The Ag-LDH coating exhibits excellent and durable antimicrobial activities against both Gram-negative (E. Coli and P. Aeruginosa) and Gram-positive (B. Subtilis and S. Aureus) bacteria. Even at the 4th recycled use, more than 99% of all types of bacteria can be killed. Moreover, the Ag-LDH coating can also effectively inhibit the bacterial growth and prevent the biofilm formation in the nutrient solutions. These newly designed Ag-LDH coatings may offer a promising antimicrobial solution for clinical and environmental applications