bluuebunny/crossref_metadata_2025 huggingface dataset:
Vector competence and correlation of midgut microbiota of Aedes albopictus for Chikungunya virus
Authors:   , Tuanudom Ranida
Published: September 2023

Chikungunya virus (CHIKV) is an important mosquito-borne virus and transmission cycle of this virus involves mosquito vectors (Aedes albopictus and Aedes aegypti) and infected vertebrate hosts. The recently studies found that CHIKV outbreak in 2007 have been  Ae. albopictus as an important vector which it was susceptible to genetic variation of CHIKV and induce to virus virulence. However, the study about vector competence for CHIKV in Thailand is limited. Moreover, the previous study indicates the impact of midgut microbiota of mosquito to viral infection. This study was conducted to examine the effects of CHIKV titers in blood meals on vector competence of Aedes albopictus (Diptera: Culicidae) and to investigate the correlation of midgut microbiota of Ae. albopictus. Six groups of Ae. albopictus were allowed to feed on different levels of CHIKV in the blood meals which were 106, 105, 104,103, 102 CID50/ml of CHIKV and the negative blood meal group. Body, legs and wings, and saliva samples from blood-fed mosquitoes were assayed for the presence of CHIKV by using immunocytochemistry staining on day 14 post blood feeding. Percent virus infection, dissemination, and transmission is defined as percent of blood-fed mosquitoes with virus in their bodies, legs and wings, and saliva, respectively. The percent infections were 83.3, 90, 100, 100, and 100%, the percent disseminations were 70.8, 86.7, 100, 90, and 98%, and the percent transmissions were 41.6, 70, 100, 90, and 82.4% after having been fed on 102, 103, 104, 105, 106 CID50/ml of CHIKV, respectively. This study suggested that Ae. albopictus are susceptible for CHIKV infection and efficient vectors for CHIKV transmission, and CHIKV titers in blood meals have effects on virus infection, dissemination, and transmission in Ae. albopictus or vector competence of this mosquito. For the bacterial isolation and identification, the midguts were cultured and 16s rRNA gene were analyzed followed by blast to gene bank database. The dominating bacterial genus was Micrococcus in infected mosquitoes after fed on CHIKV 102 CID50/ml, and it was significantly difference from the non-infected mosquitoes (P<0.04). In addition, Staphylococcus was the dominating bacterial genus in laboratory mosquitoes and it was significantly difference from field mosquitoes (P<0.0007). The correlation between midgut microbiota and CHIKV infection was not clearly indicated from this study.
KOREAN WAVE AND KOREAN FOOD FRANCHISE EXPANSION IN BANGKOK THAILAND
Authors:   , Siriwat Chanika
Published: September 2023

The objectives of this research were to investigate the relationship between Korean Wave and current Korean restaurant franchise business expansion in Bangkok and to investigate the factors affecting the decision of Thai customers who came to Korean franchise restaurants, such as general information, source of information, cost of meal, and motivation to have Korean food. This research aims to study the expansion and development of the Korean restaurant business in the case of changing popularity of Korea popular culture in the future from the perspective of Korean restaurant owners. The sample of research is customers who came to consume the Korean food at Korean restaurants in the Bangkok area and also the Korean restaurant owners from 3 stores. Questionnaires for customers were distributed and in-depth interviews with Korean business owners were conducted. The author uses quantitative approach and qualitative approach to analyze data. The sampling group are Thai teenagers and Thai workers aged 15-40 years old, the results show that, the first reason the samples customers decide to eat Korean food is because of social media. The second, is friend?s invitation. Moreover, for the reason why Korean food become a popular food in Thailand, first is taste of food. And second is popularity of Korean singers. On the part of the business owners, it is interesting that they decided to open a Korean food franchise from Korea directly, because of the popularity of Korean culture in current time.
Multi-dependent criteria supplier selection with uncertain performance evaluation
Authors:   , Anuchitchanchai Ornicha
Published: September 2023

One of the key to improve logistics efficiency of a firm is to select appropriate supplier. In order to select supplier, there are many criteria involved. Also supplier with greatest average performance does not confirm to be the most suitable one because of uncertainties. Therefore the objectives of this research are to develop decision matrix for selecting supplier based on mean-variance-skewness and identify influential criteria of supplier selection problem for Thai electronics industry. In this research, the set of criteria comprises of 6 main criteria with total of 13 sub-criteria. The data was collected via in-depth interview and questionnaire. The first three criteria which have highest important weight are lead time, follows by price, and continuous improvement ability with important weight equal to 0.0910, 0.0869 and 0.0806, respectively. To analyze skewness effect, it is found that skewness has effect on performance more than average and SD. Skewness can better distinguish between first and less priority supplier than considering only mean and SD. This result indicates that skewness really plays important role in supplier performance and should not be ignored when evaluating suppliers. Therefore, this research develops decision matrix for supplier selection including skewness, namely, Success Mode Skewness Analysis (SMSA). The validation of developed decision matrix shows that including skewness into consideration is more valid than considering only mean and SD. The findings have significant implication for both of suppliers and buyers in terms of improving logistics efficiency
SEASONAL VARIATIONS OF PICOPHYTOPLANKTON, NANOPHYTO-PLANKTON AND MICROPHYTOPLANKTON COMMUNITIES AT SICHANG ISLAND, CHONBURI PROVINCE
Authors:   , Deesuk Anassaya
Published: September 2023

Sichang Island is in the eastern part of the Inner Gulf of Thailand where is primarily influenced by two monsoon winds, the northeast monsoon and the southwest monsoon. The effect of this factor lead to changes in phytoplankton community. However, most studies have been focused on microphytoplankton community not pico- and nanophytoplankton due to their small size and study methods. Therefore, seasonal variations of pico-, nano-, and microphytoplankton around Sichang Island were observed. The samplings were conducted at 10 stations around Sichang Island in two monsoon and two intermonsoon periods. Pico- and nanophytoplankton were analyzed by flow cytometry whereas microphytoplankton were analyzed by a compound microscope. Phytoplankton abundance, size-frationated of chlorophyll a and inorganic nutrient concentrations were analyzed. The community structure of pico- nano- and microphytoplankton could be divided into four groups dominated with diatoms and Synechhococcus which were related to the main factors; temperature, salinity, and nutrient concentrations which clearly differed between seasons. Pico- and nanophytoplankton were observed as major contributor to phytoplankton biomass in all seasons except in the northeast monsoon where microphytoplankton was dominated. Flow cytometry resolved 4 groups of picophytoplankton and 5 groups of nanophytoplankton. They were high in density during the northwest monsoon in contrast to microphytoplankton density.
Quotients induced from exponents of finite commutative rings
Authors:   , Wannatong Kantapong
Published: September 2023

We use the concept of exponent of finite commutative rings to define the Carmichael quotients and the Carmichael quotients of degree d over polynomial rings over finite local rings, and then we give some congruence relations of these quotients. Moreover, we define the Carmichael quotients and the Wilson quotients over the ring of integers of number fields and study some congruence relations between them.
Non-uniform bounds on normal approximation via stein's method and exchangeable pair
Authors:   , Wannatong Kantapong
Published: September 2023

This dissertation consists of two parts. In the first, we improve the technique of Chuntee and Neammanee (2017) to obtain an exponential non-uniform bound on normal approximation for any random variables whose exchangeable pair can be constructed. Moreover, we give applications of the theorem to obtain non-uniform exponential bounds of normal approximations for sums of bounded independent random variables, the numbers of descents and inversions of permutation and combinatorial central limit theorem for real numbers. In the second part, we construct a new version of the Rosenthal inequality and improve the technique of Simcharoen and Neammanee (2016) to obtain a sharper non-uniform bound on normal approximation of a combinatorial central limit theorem under the condition of finiteness of the third moment.
Extreme anomalous clustering algorithm
Authors:   , Lisuwan Panuruk
Published: September 2023

A clustering algorithm is a process of dividing data points into disjoint clusters according to the similarity of the data points. Many researchers have presented and developed the clustering algorithms to be suitable for the different characteristics of the datasets. Therefore, the concept of the identifying anomaly data points in the dataset was adopted in this thesis to explain the similarity of the data points. The main idea is to calculate the minimum distance between data points to identify the extreme anomalous score of all data points. In this thesis, a novel clustering algorithm is proposed called the Extreme Anomalous Clustering algorithm or EAC. This algorithm specifies the extreme anomalous scores for all data points in the dataset and combines two data points with the smallest extreme anomalous score. Then the algorithm selects one data point within the cluster as the representative point which is used to consider the next combination. The experiments of this thesis are created to compare the performance of the EAC algorithm on the simulated datasets and UCI datasets with AGNES, k-means, and DBSCAN. The experimental results show that the EAC algorithm is better than the three algorithms according to the Silhouette and Rand index measurements.
Complete convergence for sequences of coordinatewise widely orthant dependent random vectors in hilbert spaces
Authors:   , Phutthanukool Teerayut
Published: September 2023

In this thesis, we introduce a new dependence concept for a sequence of random vectors taking values in real separable Hilbert spaces called coordinate-wise widely orthant dependence and extend the Baum-Katz Theorem to obtain complete convergence and complete moment convergence for a sequence of co-ordinatewise widely orthant dependent random vectors taking values in Hilbert spaces.
Strategies for playing closing octagons game in some situations
Authors:   , Leelathanakit Thitiphut
Published: September 2023

Closing Octagons game is a combinatorial game for two players that we modify from Dots and Boxes game and Dots and Hexagons game. The game starts with an m × n array of octagons such that every two adjacent octagons has one common side and 0 points for both players. Two players alternately turn by the following rules. (i) A player moves by coloring one side of an octagon. (ii) A player who colors the eighth side of k octagons earns k points and takes one more move. The game ends when every side of octagons has been colored and a player having the most points wins. This game is formulated into the new game using graphs. In order to analyze the game, more rules are added and the game with these additional rules is called normal game. In this thesis, we analyze patterns of the game and give strategies on how to play the game in several situations.
Patterns of lines intersecting on plane
Authors:   , Chamnan Wongtawan
Published: September 2023

In this work, we are interested in patterns of n lines on the plane such that lines produce M intersecting points. One famous related problem is called Fourier's 17 line problem. Although there are only a few known necessary conditions for realization, some arrangements may not even drawable. Consequently, we try to find more necessary conditions for this problem that can lead to possible arrangements and realize the arrangements. We provide a systematic algorithm to draw the possible arrangements. We establish lemmas for the direct drawing and find some certain cases of arrangements which are drawable. We also provide another approach to this problem by determining the existence of solutions that correspond to the systems of equations with conditions for each arrangement.
DESIGN AND CONTROL OF A 2-DOF REHABILITATION ROBOT WITH A TASK DEFINED IN A VIRTUAL ENVIRONMENT.
Authors:   , Angsupasirikul Natthapong
Published: September 2023

This research proposes a novel upper-limb rehabilitation robotic system. Instead of an exoskeleton type, the proposed robot is designed as active 2-DOF end-effector type moving in a horizontal plane, with being compact and easy to use with the harmless image. The rehabilitation robot system consists of a robot, a controller system and a virtual environment (game). The proposed rehabilitation robot system has been evaluated with 2 healthy subjects. The robot system has been evaluated in passive, active non-assist and active intent-based assistive rehabilitation type.
ANTIMICROBIAL EFFECT OF HIGH DOSE ASCORBATE IN MOUSE MODEL WITH BACTERIAL INFECTION
Authors:   , Wirapakorn Chulamartd
Published: September 2023

Ascorbate or Vitamin C is a vitamin that is important to the body. It contributes to the immunity, involves the collagen formation, acts as an antioxidant and has the ability to destroy cancer cells and bacteria. These abilities depend on the concentration of ascorbate. Bactericidal properties of ascorbate were interesting, especially in the high concentrations. Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli are a common etiologies of nosocomial infection in Thailand and worldwide. These bacteria have developed mechanisms of antibiotics resistance and cause more violence in the disease. Hence, the time-killing assay was used to explore the bactericidal synergy of ascorbate in the administration with ceftriaxone, a common antibiotic. The results showed that ascorbate concentrations of 10 and 40 millimolar (mM) with ceftriaxone at the concentration of minimal inhibitory concentration (1X MIC) could inhibit the growth of S. aureus (ATCC strain) both in in vitro and in vivo but not effective against P.aeruginosa, A. baumannii and E.coli. In addition, ascorbate alone at 250mM could inhibit the growth of S. aureus and P. aeruginosa. Moreover, ascorbate 10 and 40 millimolar can increase macrophage killing activity to S. aureus and P. aeruginosa. In parallel, MRSA clinical strains were tested with the time-kill assay in vitro for the prediction of the in vivo clinical responses in S. aureus-induced myositis mouse model. Indeed, the synergy in the time-kill assay of ascorbate plus ceftriaxone associate with the favorable outcome in myositis model. In conclusion, ascorbate antibiotic synergy against S. aureus-induced myositis was predictable by the time kill assay. This method might be valuable to select the patients potentially benefit from Ascorbate-adjuvant therapy, especially, against the antibiotic-resistant bacteria.
FUNCTIONAL CHARACTERIZATION OF NATURAL SUNSCREEN COMPOUND MYCOSPORINE-2-GLYCINE FROM EXTREMOPHILIC CYANOBACTERIUM Halothece sp. PCC 7418 IN MACROPHAGE CELL LINE AND FRESH WATER CYANOBACTERIUM
Authors:   , Tarasuntisuk Supamate
Published: September 2023

Mycosporine-2-glycine (M2G) is a rare UV-screening compound in a group of mycosporine-like amino acids (MAAs). This molecule is found in only two cyanobacteria; Euhalothece sp. LK-1 and Aphanothece halophytica (Halothece sp. PCC 7418). The structure of M2G composed of 4-deoxygadusol as a core structure, attached by 2 molecules of glycine at C1 and C3 positions. M2G has a maximal adsorption at 331 nm and a better antioxidative activity than other MAAs. Thus, it is interesting in determination of other activities for further cosmeceutical and pharmaceutical applications. In this study, a high purity M2G was successfully extracted and purified from Halothece sp. PCC 7418 by using strong cation exchange chromatography, and reverse phase chromatography, respectively. The obtained M2G has a very low concentration of endotoxin (0.004 EU/mL). 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay found that M2G exhibited the highest radical scavenging activity at pH 6. In this study, anti-inflammatory activity of M2G in RAW 264.7 murine macrophage cell line at the transcriptional level under lipopolysaccharide inflammatory-induction was also examined. It revealed that iNOS, encoding inducible nitric oxide synthase enzyme, was highly suppressed by M2G (75±2 %). This is consistent with a decrease in nitric oxide level. COX-2 expression was also suppressed at < 10 µM M2G treatment. Anti-oxidative capability of M2G was inspected in transcriptional level under oxidative stress induced by H2O2. It was found that 5 µM of M2G suppressed sod1, which encodes the radical scavenging enzyme Cu/Zn SOD. Other antioxidant-related genes; cat, Hmox1, and Nrf2, were upregulated by the supportive of M2G as well. Heterologous expression of M2G biosynthetic gene cluster (Ap3858-Ap3855) in a fresh water cyanobacterium Synechococcus elongatus PCC 7942 revealed a higher H2O2-induced oxidative stress tolerance than that of the control cells. IC50 of H2O2 in the transformant cells harboring M2G genes and the control cells were 2.293±0.06 and 1.523±0.05, respectively. Transcriptional level of antioxidant genes in expressing cells revealed that cat, sodB, and tpxA, were 4.5±0.4, 2±0.2 and 5±0.2 times upregulated, respectively, under H2O2 oxidative stress.
Theoretical studies on electronic properties of curved graphene quantum dots and lithium adsorption on graphene quantum dots
Authors:   , Pattarapongdilok Naruwan
Published: September 2023

Graphene quantum dots (GQDs), with their attractive properties, are of interest to apply for electronic devices. Therefore, this dissertation aimed to investigate the electronic of curved graphene quantum dots (CGQDs) and the adsorption of lithium on GQDs. For the first part, two shapes of flat GQDs, rhomboidal (RGQDs) and hexagonal (HGQDs), were modified to make CGQDs with different folding axes and angles. Stabilities and electronic properties of CGQDs were studied using PBE/DNP. The results showed that the deformation energies of GQDs depend on sizes and folding axes but not their shapes. HOMO-LUMO gap variations, both widening and narrowing the gap, upon folding were observed, and can be explained by orbital interactions. In the second study, three sizes of GQDs, coronene, circumcoronene, and circumcircumcoronene were allowed to be adsorbed by lithium ions and atoms at various positions of GQDs. Adsorption positions and binding energies were determined using M06-2X/6-31g(d). The results indicated that lithium ion and atom could bind better at the edge of GQDs. The adsorption between lithium ion and coronene showed the highest binding affinity of -135.073 kcal/mol. Moreover, the size increment of GQDs raises the binding energy, except Li+ absorption on GQDs with -1 charge. Preferred adsorption positions of lithium ions and atoms on GQDs can be described by the total charge of six-membered ring. In addition, binding affinities of one-Li-ion system on GQDs are larger than two-Li-ion system. For two Li-ion system, the binding energy on GQDs also depends on Li ion-Li ion repulsion.
Development of innovative high-energy neutron and gamma-ray shielding material based on high density cement and crumb rubber
Authors:   , Aim-o Pawitra
Published: September 2023

The incorporation of carbon and hydrogen-rich material into radiation shielding material can improve its shielding performance. High-density cement mixed with crumb rubber was studied to be a gamma ray and neutron shielding material. Shielding materials were designed using high-density cement mixed with 5 – 25 vol% of crumb rubber. Monte Carlo N-Particle code was employed to simulate radiation shielding performances of the composed materials. The utilized neutron and photon sources were Am-241/Be and Co-60, respectively. These shielding designs were fabricated and experimentally evaluated on the radiation shielding properties. The cracking mechanism of high-density cement mixed with lead (HDCRL) was also investigated. The quantitative X-ray diffraction technique (QXRD) was used to determine the crystalline phases as well as elemental compositions of HDCRL. Buildup factors from gamma ray scattering, prompt and secondary gamma ray emissions from the neutron capture interaction were also evaluated. The prompt and secondary gamma ray emissions were determined using Prompt Gamma Neutron Activation Analysis (PGNAA). In addition, the mechanical properties of samples were evaluated using the Compressive Testing Machine (CTM). The high-density cement mixed with 5 vol% crumb rubber and 5 vol% lead powder demonstrated the highest neutron and gamma ray shielding performances. The neutron and photon attenuations were 64% and 68%, respectively, better than ordinary concrete. Analysis of the cracking mechanism of HDCRL revealed six crystalline phases: barite, portlandite, quartz, calcite, lead and PbO2. The weak adhesion of lead powder to high-density cement was the main cause of cracking. For photon interaction, the gamma interaction with high-density cement mixed with crumb rubber increased the buildup factor; however, the value was close to unity leading to the conclusion that the secondary gamma ray and prompt gamma ray were not present. For neutron interaction, no prompt or secondary gamma ray emission was detected using PGNAA technique. The average compressive strength indicated that the high-density cement mixed with 5 vol% crumb rubber exhibited higher strength than other specimens and that increasing the crumb rubber content decreased the mechanical property. This innovative composite radiation shielding material not only benefits nuclear science and engineering applications, but also helps solve the environmental issue of waste rubber.
Antiproliferative activity against Jurkat cells of SAHM1 peptide conjugated gold nanoparticles
Authors:   , Thippayamonta Mukthida
Published: September 2023

In general, treatments of cancer may involve medication, surgery, radiation and chemotherapy. Although these treatments are successful at a certain satisfactory level, their side effects are not acceptable for some patients. Thus, many researches have been investigated alternative methods to cure cancer. A technique of interest is the use of targeted drug therapy in which drug is designed to selectively kill only the cancer cells and to do no harm on the normal cells. Stapled α-helical peptide derived from mastermind-like I or SAHM1 is a small peptide which has been reported to have antiproliferative activity against cancer cells. However, its use is limited by degradation during cell penetration and transport inside the cell. In this study, gold nanoparticles (GNPs) were studies as the carrier of SAHM1 in penetrating into Jurkat cells in order to enhance antiproliferative activity of SAHM1. GNPs were synthesized by reaction between trisodium citrate and HAuCl4 at different conditions to obtain the particles with the averaged size of 20 nm, 40 nm and 60nm. SAHM1 was attached to the GNPs using thiolated polyethylene glycol (PEG) as the linker. Cytotoxicity of GNPs, thiolated PEG, thiolated PEG-GNPs, SAHM1 and SAHM1-(thiolated PEG)-GNPs was investigated by conventional MTT assay. Cell viabilities of Jurkat cells decreased to about 70% when separately treated with GNPs, SAHM1 and thiolated PEG-GNPs as compared to those of the untreated cells. Cell viabilities of the cell treated with SAHM1-GNPs noticeably decreased only when 20 nm GNPs coated with 62.5 µM and 125 µM SAHM1 were used as compared to those of cells treated with GNPs, thiolated PEG, thiolated PEG-GNPs and SAHM1. Therefore, enhancement of antiproliferative activity of SAHM1 was found when 20 nm GNPs coated with 62.5 µM and 125 µM SAHM1 were used. Study of mode of program cell death by staining cells with Annexin V and propidium iodide after cell treatment with SAHM1-GNPs for 24 h and 48 h revealed that most cells died in early apoptosis and late apoptosis.
Prevalence Of Chronic Temporomandibular Disorder Pain And Comorbidities In A Group Of Thai Patient: A Cross Sectional Study
Authors:   , Nguyen Tra
Published: September 2023

Objectives: 1. to investigate the prevalence of chronic temporomandibular disorder (TMD) and its comorbidities in a group of Thai patients; 2. to evaluate the relationship between pain parameters (pain duration, pain intensity, and pain frequency) with the number of comorbidities and widespread pain index (WPI); 3. to assess the relationship between the presence of chronic pain with familial history in TMD pain patients. Methods: A cross-sectional study was undertaken of 351 outpatients. Patients were given an interviewer-administered questionnaire which contained four parts (demographic data, pain parameters, WPI and comorbidities diagnosis). Diagnosis was made in accordance with Diagnostic Criteria for Temporomandibular Disorder. Spearman rank correlation coefficient linear regression, and Chi-square test were used, with a significance level of p ≤ 0.05. Results: 25% reported chronic pain. 82% of chronic pain patients had at least one comorbidity. The number of comorbidities was associated with pain duration (p = 0.02); WPI was related to pain duration and pain intensity (p < 0.001). The presence of chronic TMD pain was not related to familial history (OR = 1.31; 95% CI = 0.78 – 2.21). Conclusions: The presence of comorbidity was prevalent in chronic TMD pain patients. To predict the presence of comorbidities or spreading pain presence, pain duration is a feasible factor. Pain intensity can be used to predict the presence of spreading pain, but its reliability is not clear.
Separation and purification of lactic acid from fermentation broth by reverse osmosis
Authors:   , Phanthumchinda Natnirin
Published: September 2023

Brackish water reverse osmosis (BWRO) and seawater reverse osmosis (SWRO) membranes were used in the 2-stage reverse osmosis (RO) unit to recover, pre-purify, and pre-concentrate lactic acid. Calcium lactate (CaLAC), sodium lactate (NaLAC), and ammonium lactate (NH4LAC) were used as model feed solutions. The operating pressure showed a pronounced effect on lactate passage through the first BWRO unit, and the Donnan exclusion effect and hydrogen bonding were responsible for cation rejection. Calcium ions were rejected at the BWRO unit because of low diffusion rate and charge interaction at the surface. However, monovalent ions formed hydrogen bonds with the carbonyl group of the membrane that allowed passage across the membrane. The second SWRO unit was for pre-concentrating lactic acid. A high lactate purity of 99.2% with a total recovery of 50.5% was acquired from calcium lactate feed solution. Lower purity with higher lactate recovery was obtained when the feed solution was sodium lactate and ammonium lactate. Process and cost models for lactic acid recovery from fermentation broths at an annual capacity of 100,000 kg were developed as a research tool in evaluating an alternated process technology. The models were developed using SuperPro® Designer software by gathering the optimized data from the laboratory scale experiments. Sizing of unit operations, chemicals and utility consumptions, and estimation of capital and operating costs with the cost breakdown analysis were acquired from the simulation. Membrane based process design was proposed in this study. The processes mainly consisted of microfiltration for cell removal, a series of ultrafiltration for eliminating proteins, and the integrated reverse osmosis systems to recover, preconcentrate, and prepurify lactic acid. Among the 3 proposed process designs, in-parallel membrane based process exhibited the highest lactic acid recovery yield while the purity remained sufficiently high in comparable to the commercial grade products. The number of unit operations was found to be responsible to high production cost both investment and operating costs. Omitting centrifugation and ultrafiltration at 30 kDa molecular weight cut-off with integrated brackish water reverse osmosis membrane in parallel units in the design could lower the operating cost by 23.33-31.29% for different fermentation broths entering the downstream processing units.
Assisted Methane Hydrate Formation with the Addition of Promoters
Authors:   , Jaikwang Chutikan
Published: September 2023

Natural gas hydrates play an important role in the largest reservoir of hydrocarbons on earth. The gas hydrates have received increasing attention in an excellent way of new technology for gas in large quantity storage and transportation. However, the main challenge to use methane hy¬drates has faced many challenges such as the slow formation rate, low growth rate during hydrate formation, and low conversion ratio of gas to solid hydrates leading to poor storage capacity. In this work, methane hydrate formation and dissociation in the presence of different Cyclopentane (CP), Tetra-n-butyl phosphonium bromide (TBPB) and Tetra-n-butyl ammonium bromide (TBAB) concentrations were investigated. The formation experiment was conducted in an unstirred system. The temperature was controlled between 2.5 and 4.0°C at 8 MPa. The hydrate dissociation experiment was performed after the completion of hydrate formation. The results showed that the presence of TBPB alone was not sufficient to promote methane hydrate formation. The addition of TBAB to promoted methane hydrate formation with only small amount of methane uptake. Increasing the concentration of CP improved methane consumption. However, the methane consumption in the presence of CP was higher than that with TBAB.
Effects of bead size and concentration of unstable asphaltenes obtained from different centrifugation techniques on asphaltene deposition in packed bed apparatus
Authors:   , Lao Kimchhay
Published: September 2023

Asphaltenes are the heaviest and most polar fraction of petroleum crude oil. They are the collection of components that can be soluble in aromatics solvents such as benzene or toluene, but insoluble in normal alkanes, n-pentane, n-hexane, or n- heptane. Asphaltenes are a class of molecules consisted of grouped aromatic rings with alkane chains. Changing pressure, temperature, composition, and shear rate during transportation can cause precipitation and deposition, resulting in reduced reservoir productivity due to restricted flow lines, fouling and blockages in the pore spaces of the reservoir. The goal of this investigation is to assess validity of two aspects of the packed bed asphaltene deposition methodology and model. The first aspect is on the validity of diffusion coefficient used in the deposition model with respect to bead size in packed bed; the second aspect is on the relationship between the concentration of unstable asphaltenes, the method to measure this concentration, and the deposition rate. In the first part, it was observed that the deposition rate increases as the bead size decreases, as is predicted by the diffusion-limited deposition model used. In the second part, results indicate that concentration of unstable asphaltenes based on long time centrifugation of fresh oil-heptane mixture is the appropriate scalin g for asphaltene deposition rate, instead of aged oil-heptane mixtures.
Microemulsion Formation of Vegetable Oils Using Mixed Extended Surfactant for Cleaning Applications
Authors:   , Jariyawattanarat Siriluk
Published: September 2023

Some vegetable oils and animal fats can form semi-solid crystalline. The formation of semi-solid fats or waxy soils results in weak interactions between the oil and surfactant during the cleaning process. In this study, the anionic extended surfac-tant (C14-15, 8PO-SO4) systems were employed to form a middle phase microemul-sion with various vegetable oils (coconut, palm and soybean oil). The addition of nonionic extended surfactant (C16-18, 2PO-4EO-OH) in the mixed surfactant systems was also evaluated to observe the solubility enhancement of oil and water phase. The IFT value of formulated surfactant systems was measured to determine the optimum salinity. The Hydrophilic-Lipophilic Deviation (HLD) concept was conducted to es-timate the required Cc and K parameter for examination of the correlation with the experiment. It was found that the extended surfactant systems formed the middle phase microemulsion with coconut, palm and soybean oil at the optimum salinity of 7 wt%, 8 wt% and 9 wt% NaCl, respectively. For the mixed system with the nonionic surfactant, the middle phase microemulsion formed at lower optimum salin-ity than that of the single surfactant system. The negative Cc value that obtained from HLD equation indicated that the hydrophilic surfactant property. For hard sur-face cleaning, the oil removal efficiency of mixed surfactant system is higher than the single surfactant system alone. The results obtained in this study improve the bet-ter understanding of the surfactant selection for vegetable oil microemulsions as well as semi-solid fats in cleaning application.
Improvement of life cycle assessment software and its applications
Authors:   , Chavewanmas Yodsathorn
Published: September 2023

LCSoft is Life Cycle Assessment (LCA) software which developed for perform LCA together with process design. It is a stand-alone tool with ability to be integrated with other process design tools such as process simulation software (PROII/ASPEN), economic analysis tool (ECON), and sustainable process design tool (SustainPro). In addition, several optional interpretation features are available such as, sensitivity analysis, alternative comparison, and eco-efficiency evaluation. In this research, LCSoft had been improved in performance and application range. The development framework consisted of four tasks. The first task deals with improvement of LCI and LCIA calculation which new pathway for calculation and allocation had been added. The second task deals with new features development which including normalization, parameter sensitivity analysis, data quality indicator, and endpoint impact categories. The third task deals with extension of LCI data in order to cover all of impact categories calculation. The fourth task deals with validation of LCSoft software. The integrated software was validated and verified by comparing assessment results for bioethanol production from cassava rhizome process and for Para-xylene production by Toluene Methylation as case studies and compared with other commercial LCA software. The results indicated that the new feature of LCSoft provided reliable calculations very efficiently, and were especially useful for chemical and biochemical sustainable process design studies.
Mixed metal oxide catalysts derived from natural sources for production of fatty acid methyl esters
Authors:   , Jindapon Wayu
Published: September 2023

The objectives of this research are to study active sites of Ca-based catalysts derived from calcite (CaCO3) and dolomite (CaMg(CO3)2), and to clarify catalytic effect of MgO in the calcined dolomite as catalyst in transesterification of palm oil with methanol. Firstly, the effects of calcination temperature on evolution of MgO in dolomite and its catalytic activity were studied. The MgO containing in the calcined dolomite was not active, while the main active site was CaO. However, Ca and Mg mixed oxides obtained from calcined dolomite had higher activity than that prepared by physical mixing in which calcite and magnesite (MgCO3) were mixed at the same metal composition as dolomite. The results indicated that the presence of MgO in the calcined dolomite reduced the CaO crystallite size, and stabilized the catalytic activity. The direct reaction of Ca-based oxides with methanol indicated that the calcined dolomite with smaller CaO crystallites gave higher formation rate of calcium methoxide (Ca(OCH3)2) than the pure CaO. In the case of direct reaction with glycerol, the formation of calcium glyceroxide (Ca(C3H7O3)2), related with leaching of calcium active phase, was delayed over the mixed oxide catalysts. Subsequently, the Ca-based oxides were prepared in form of Ca-based methoxides and glyceroxides and tested in the transesterification. Since the Ca-based oxides had a higher initial rate than the others, they were easily changed to other calcium compounds, such as Ca(OH)2, CaCO3 and Ca(C3H7O2)2 during the transesterification. The Ca-based methoxides were more stable than the Ca-based oxides although their activity was the least. On the other hand, the Ca-based glyceroxides promoted the reaction via homogenous catalysis routes. The structural stability of catalysts exposed to ambient air was investigated since CO2 and moisture were strongly chemisorbed onto the basic sites, leading to catalyst deactivation. The Ca-based oxides were the most stable catalysts because the Ca(OH)2 generated was somewhat active. Finally, the Ca-based catalysts in extrudate form were used in biodiesel production using continuous-flow fixed-bed reactor. The effects of hydroxyethyl cellulose addition on the extrusion and the characteristics of the extrudates obtained were studied. Premixing the catalyst extrudates with different types of commercial methyl esters (CMEs) resulted in a stable FAME yield of ≈96.5% throughout the operation. This beneficial effect arises from high solubilities of both reactants in the CME layer covering the catalyst extrudates.
Metallosalen-based polymers for reduction of carbon dioxide
Authors:   , Kaewyai Cherawat
Published: September 2023

In this research, a series of novel asymmetric copper- and nickel-salens bearing thiophene-based substituents were successfully synthesized and characterized by nuclear magnetic resonance spectroscopy and mass spectrometry.  Homogeneous electrocatalytic activities of these monomers toward reduction of CO2 were investigated using cyclic voltammetry technique.  Electrochemical studies showed these salen monomers are able to serve as catalysts in the electrochemical reduction of CO2 due to the significantly increase of the current observed under CO2-saturated condition, compared with those found under the N2-saturated one.  Results also revealed that insertion of the carbon-carbon triple-bond between the thiophene-based substituents and the salen core led to the lower required reduction potential, while the additional thiophene rings did not significantly influence in this aspect.  Furthermore, addition of 3% of H2O as a proton source resulted in even higher current enhancement in the reduction of CO2.  Electropolymerization of the target monomers through their thiophene-based units gave desirable metallosalen-based polymers in most cases.  In the polymerization process, results showed that the introduction of bithiophenyl rings led to the lower required oxidation potential, while the derivatives containing carbon-carbon triple-bond spacers required higher oxidation potential than those having the thiophene-based substituents directly linked to the salen cores.  However, further optimization of the polymerization condition is required to obtain more efficient films for the reduction of CO2.
Effect of corrosion inhibitors in lubricant for electronic industry
Authors:   , Maipul Natclitta
Published: September 2023

The selected functional polymers and fatty esters of poly)1-butene pyrrolidone) (PP) and propylene glycol monostearate (PG) were investigated and applied to use as the corrosion inhibitors for protecting material removal during read/write head lapping processes in hard disk drive (HDD) production. Potentiodynamic polarization measurement was used to study their corrosion behaviors against antiferromagnetic materials (IrMn) which are the most sensitive materials in the head structure. Corrosion rate of PP- and PG-modified lubricants were 0.086 and 0.084 Å/min, respectively, while standard lubricant was 0.111 Å/min. Moreover, the leaching out of metallic atoms was investigated by using inductively couple plasma mass spectroscopy (ICP-MS). Leaching out of metallic atoms was in range 3-7 µg/L for PP- and PG-modified lubricant but, standard lubricant was 4-15 µg/L. The results showed that corrosion rate can be reduced compared to the standard glycol-based lubricant. The conductivity and acid-base properties of the modified lubricants were also measured and analyzed.  Scanning electron microscopy (SEM) showed that the protection of those inhibitors came from the formation of protective thin layer over the surface by their functional groups.  Furthermore, the electrical performance parameters from quasi static test (QST) and lapping test indicated a better lapping performance, without losing quality and electrical performance of the slider. We propose that PG and PP are the 1st and 2nd choice of additional additives in corrosion protection of IrMn material in HDD slider fabrication process.
Antibacterial agents from Dracaena cochinchinensis (Lour.) S.C.Chen and Eleutherine americana (Aubl.) Merr. Ex K. Heyne
Authors:   , Ruga Ritbey
Published: September 2023

Fifteen compounds including two new anthraquinones (118-119), two naturally occurring new compounds (116-117) and eleven known compounds were successfully isolated from the CH2Cl2 extracts of Dracaena cochinchinensis and Eleutherine americana i.e. dihydrochalcones (5 and 23), pterostilbene (27), homoisoflavanones (15 and 82-84), naphthalenes (85 and 116), pyranonaphthoquinone (86) and anthraquinones (99-100 and 117-119). Among isolated compounds, (+)-eleutherin (86) was the most potent antibacterial agent against Propionibacterium acnes KCCM 41747, Staphylococcus aureus ATCC 25923, Streptococcus sobrinus KCCM 11898, Streptococcus mutans ATCC 25175 and Salmonella typhi ATCC 422 with inhibition zones of 14.7 to 18.0 mm and MIC values of 0.24 to 7.8 µM. Compound 86 showed bacteriostatic effect against P. acnes while bactericidal agent was observed by this compound against other tested bacteria. The combination of chloramphenicol and 86 demonstrated synergistic effect against all tested bacteria.  Moreover, anti-allergic activity of nine compounds on the release of β-hexosaminidase in rat basophil leukemia (RBL-2H3) cells by calcium ionophore A23178-induced stimulation were investigated. Loureirin B (5) showed the strongest activity followed by 23 and 27 with IC50 values of 7.8, 15.8 and 17.5 µM, respectively. For anticancer activity, 86 suppressed the growth of HeLa, HCT116 and HepG2 cancer cell lines with IC50 values of 0.3, 4.6 and 6.7 µM, respectively. Compound 86 displayed twice more toxic than positive control (5-fluorourasil) against HeLa cells. The suppression against the cell was also shown by 23 and 27 with IC50 value of 1.4 µM.
Development of hydrogen embrittlement resisted pd-cu alloy membrane
Authors:   , Chukiatthai Ratchaneekorn
Published: September 2023

The development of PdCu alloy membranes that can be used in hydrogen separation at low working temperature (<300°C) without hydrogen embrittlement problem is a very attractive topic for the petrochemical industry. Pd–Cu membranes have been prepared by electroless plating and electroplating method on stainless steel support. The compositions of the PdCu alloy membranes were related to both the metal deposition rates. The appropriate annealing temperature of Pd–Cu membranes was found at 500 °C in argon atmosphere for 24 hours to form a complete alloy material. After thermal annealing, the Cu atom was distributed in Pd alloy membrane. The surface morphology, compositions, and crystallinity of the PdCu alloy membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The best Pd contents in PdCu alloy membrane were about 84 and 75 %at. The hydrogen flux through the PdCu alloy membrane was measured at temperature 150 to 300 °C and differential pressure 0.5 to 2.5 bar for membrane stability. The hydrogen flux increased with increasing temperature and pressure. Adding Cu atoms in Pd can reduce strain in Pd lattice structure. Both PdCu alloy membrane can be operated at the lower temperature than a critical temperature of pure Pd membrane without hydrogen embrittlement.
Analysis of biomarkers in crude oils, processed oils, and spilled oils
Authors:   , Hattakijvilai Pornpetch
Published: September 2023

Oil spills in marine are commonly come from crude oils, fuel oils and lubricating oils by accidental leakages or purposeful discharges to the surroundings. As crude oil and fuel oil which refined from the heavy fraction of crude oil have similar physical properties especially if they were weathering, it is difficult to differentiate that the spill has the origin from crude oil or fuel oil. In this study, five crude oils, two fuel oils, one fresh and one used lube oil that are typically used in Thailand were investigated. All crude oils, fuel oils, and used lube oil were weathered in the sea water. All samples were characterized using GC-FID and GCxGC TOFMS. The attention of this work is focused on the distribution pattern of polycyclic aromatic hydrocarbons (PAHs) such as phenanthrenes (P), anthracenes (A), dibenzothiophenes (D) and their alkylation, and biomarkers in hopanes group. The statistic method was applied to distinguish crude oils, fuel oils and lube oil. The results from GC-FID showed a useful basis information of hydrocarbon in oils which could distinguish lube oil from other oil type due to the huge unresolved complex mixture (UCM). The distribution patterns of methyl-phenanthrenes (MP) and methyl-anthracenes (MA) were different in most crude oils and processed oils. The double ratio plots of MP and MA showed the most positive method to differentiate two refined products and crude oils. The results from weathering simulation showed that biomarkers were high degradation-resistant, however, hopanes distribution patterns were different between fuel oils and their crude oil feedstocks. In addition, the distribution pattern of hopanes biomarker in fresh or unused lube oil and used lube oil were dissimilar as they were generated or degraded during the combustion in the engine.
The Incipient Layer of Wax Deposit
Authors:   , Ketjuntiwa Tunya
Published: September 2023

The formation of the incipient layer of wax deposit when waxy oil is exposed to a cold surface is studied. Using a cold-finger apparatus, the evolution of deposit thickness is monitored with a video camera, allowing one to resolve the deposit layer formation from inception up to long times where deposit thickness no longer times where deposit thickness no longer grows. Characterization of wax deposits show that incipient layer has identical composition to waxy oil, indicating that deposit is not formed by a diffusion process. Modelling shows deposit formation at the investigated conditions cannot be explained by a diffusion process.