Asia-Pacific Journal of Science and Technology

The influence of interfacial bond between substrate and overlay concrete by bi-surface shear test and split prism test

Kavendra Pulkit, Babita Saini, Hanuman D. Chalak — Thu, 27 Jun 2024 00:00:00 +0700

The interfacial bonding between damaged concrete structures and newly applied repair materials is one of the significant issues for the structure’s functionality, safety, and durability. To prevent failure, a strong bond is required at the interface. This paper investigates the interfacial bond strength for different concrete mixes and the surface patterns used. In the present experimental study, three concrete mixtures, M20, M30, and M45 were used for substrate concrete casting, and based on the 28 days strength of substrate concrete, the concrete overlay mix of the same strength was used. Rectangular groove, V-type groove, U-type groove, S-type groove, Trapezoidal groove patterns, and As-cast with or without an Epoxy-based agent were used as different surface profiles on the substrate surface. Two types of direct shear tests, the Bi- Surface Shear test and the Splitting Prism test, were used to measure the bond strength after 28 and 56 days. The results concluded that at 28 and 56 days, the RG and EB had higher bond strength compared to the As-cast for both BSST and SPT.

Evaluation of the PV design based on minimum percentage of energy saving

Thu, 27 Jun 2024 00:00:00 +0700

In Thailand, the use of photovoltaic (PV) energy technology is growing in popularity in the industrial sector to reduce the amount of electricity drawn from the grid. Before the system is installed, the owner must make investment decisions by evaluating the production potential of the PV system. PV sizing is designed using a simplified method under energy-saving circumstances. With the aid of this technique, the engineer can easily design the PV capacity installation and specify PV sizing in the design program. As a case study, power flow assessment was applied to a wastewater treatment system in Sakon Nakhon, Thailand. The results showed that it consumed an average of 3,643 kWh of energy per day and the plant needed to save 10% of this amount of energy annually. Consequently, the optimal capacity for the system was 101 kWp, while the approximate PV sizing was 103.8 kW, depending on factory conditions. The combined energy output of the grid and the PV system was injected into the 950.86 MWh/year electric load. The entire annual energy output from the PV system was 108.24 MWh, with the energy flow from the grid being 842.62 MWh. Based on current (2023) PV market prices, the typical installation cost was THB 27.44/W, with a payback period of 5.3 years. The developed PV system should assist the wastewater treatment plant with predicted yearly energy savings of 11.4%.

Bioactive compounds from marine red alga Acanthophora spicifera associated bacteria against diabetic foot ulcer derived bacterial isolates

Thu, 27 Jun 2024 00:00:00 +0700

Infection by extremely drug resistant pathogens increases the risks associated with diabetic foot ulcers and there is a need for new antibacterial agents to treat them. In this study, biocompounds from heterotrohic bacteria associated with autotrophic red alga Acanthophora spicifera were tested for antibacterial and antibiofilming potency against pathogens isolated from diabetic foot ulcers. Pus samples from thirty diabetic foot ulcers from a tertiary care hospital were processed for microbiological examination and antibiogram test. Epiphytic and endophytic heterotrophic bacteria isolated from red alga were screened for antagonistic activity against the extensively drug resistant pathogens using dot plate assay and cross streak assay. Extracts of potential bacteria were tested for anti-pathogenic, anti-biofilming and anti-inflammatory properties. Gas chromatography- mass spectrometry analysis on crude bioactive extract was carried out. Ulcers revealed polymicrobial type infection. The antibiogram study revealed extremely drug resistant extensively drug resistant pathogens in 15% of isolates. Among 28 endo and exo symbiotic heterotrophic bacterial isolates, an epiphytic Bacillus was found highly antagonistic to extensively drug resistant pathogens. Bacterial extract proved bactericidal with minimum inhibitory concentration value of 64 µg/mL for Gram positive pathogens and 128 µg/ml for Gram negative pathogens. The extract inhibited biofilming of pathogens at 1000 and 500 ppm levels. Gas chromatography- mass spectrometry analysis of crude extract revealed compounds having antibacterial, antibiofilming and anti-inflammatory activities. The study suggests that Acanthophora spicifera associated Bacillus may serve a good source of pharmaceutical lead in designing drugs to treat and cure diabetic foot infection due to extensively drug resistant pathogens.

A preliminary assessment of heavy metal (Pb, Cd, and As) contamination in the leaves and cultivation area of Mitragyna speciosa (Korth.) originating from Thailand

Atikarn Janthongkaw, Tanaporn Khamphaya, Supabhorn Yimthiang, Phisit Pouyfung — Thu, 27 Jun 2024 00:00:00 +0700

Kratom (Mitragyna speciosa (Korth.)) is a plant with various therapeutic applications, treating such ailments as chronic pain and diabetes. Its primary alkaloid, mitragynine, exhibits opioid-like effects without respiratory depression; thus, kratom may be used to treat opioid addiction. However, heavy metal contamination can compromise kratom’s safety and quality. This study examined heavy metal contamination (from arsenic [As], cadmium [Cd], and lead [Pb]) in Thai kratom cultivation areas and dried leaves using inductively coupled plasma mass spectrometry (ICP-MS). Mitragynine concentrations in green Thai kratom (GTK) and red Thai kratom (RTK) were also quantified. The analysis revealed that the As, Pb, and Cr levels in kratom leaves were below the safety thresholds, but soil samples showed significantly high As contamination (177.94±1.30 mg/kg). Mitragynine concentrations were higher in GTK (52.68 mg/g _{(Ethanol extract)}) compared with RTK (39.77 mg/g _{(Ethanol extract)}). The findings provide essential information on heavy metal contamination and mitragynine content in kratom leaves and cultivation areas. While safe levels of heavy metals were found in leaves, elevated As concentrations in soil samples raise concerns about long-term contamination risks. The mitragynine content variability between GTK and RTK warrants further investigation to understand its pharmacological and therapeutic implications. This study emphasizes the need for continued kratom research to ensure kratom’s safe and effective use in traditional and modern medicine.

Uterine pathology of women with antenatally diagnosed placenta accreta spectrum (PAS) disorders

Thu, 27 Jun 2024 00:00:00 +0700

To determine the rate of women with antenatally diagnosed placenta accreta spectrum (PAS) who are pathologically unconfirmed and associated factors. This study was conducted in the Department of Obstetrics and Gynecology, Faculty of Medicine, Khon Kaen University, Thailand. Medical records of women with an antenatal diagnosis of PAS who underwent hysterectomy between January 2015 and July 2022 were reviewed. Records of 50 women were reviewed. All women had placenta previa, and most (94.0%) had a prior history of cesarean delivery. Four women were found to have no PAS on pathological examination, accounting for a false-positive rate of 8.0% (95% confidence interval 2.20%-19.2%). Coexisting adenomyosis was more likely to be noted among women without PAS on pathologic examination than among those with pathologically confirmed PAS (50.0% versus 17.8%, respectively). Among women with clinically suspected extensive myometrial involvement, grade 3 PAS was pathologically diagnosed in only 57.1% with coexisting adenomyosis, that was lower than that in women without adenomyosis (84.6%). The false-positive rate of prenatal PAS diagnosis in this study was 8.0%. Coexisting adenomyosis appeared to affect the accuracy of the antenatal diagnosis of PAS.

Development of charcoal briquettes from rubber seed shells mixed with food waste binder as an alternative energy source

Sucheera Laocharoen, Parinyapan Phetcharat, Chonlawit Yuvajita, Sunan Nuanpeng — Thu, 27 Jun 2024 00:00:00 +0700

Rubber seed shells (RSS) are an abundant biomass in Thailand that can be used as a source of charcoal briquettes for alternative energy. Food waste from the domestic sector also has the potential to be used as an effective binder in the production of charcoal briquettes. This research aimed to develop charcoal briquettes from RSS using food waste as an alternative binder material. The ratio of RSS charcoal to food waste binder was varied at 2 :1, 5 :1, and 10 :1 (v/v). Cassava starch, a popular and conventional binder, was used as a binder to compare with food waste. Cylindrical charcoal briquettes, 40 mm in diameter and 40 mm long, were formed by a hydraulic press with a pressing force of 1 ton. The results show that the variation in the charcoal: binder (C: B) ratio affected the bulk density, moisture, ash, volatile matter content, heating value, and compressive strength. RSS charcoal briquettes at a C: B ratio of 1:1 was considered suitable because they had the highest heating value and a relatively high compressive strength of 6,219 ± 229 cal/g and 53.29 ± 2.91 N/cm², respectively. The moisture content and heating value of this RSS charcoal briquette are within the range set by the Thai Industrial Standard Institute (TISI) standard. The heating value of RSS charcoal briquettes made from food waste binder at a suitable C:B ratio (10 :1) was not significantly different from those made from cassava starch binder at the same C:B ratio, but the compressive strength was significantly lower.

Investigating the influence of processing parameters on bimetallic catalysts for high-yield carbon nanotube synthesis

Abayomi A. Okesola, K. Mensah-Darkwa, Nthabiseng B. Maledi, Anthony Andrews — Thu, 27 Jun 2024 00:00:00 +0700

The efficient synthesis of carbon nanotubes (CNTs) remains a challenge, and optimizing processing conditions for high-quality CNT production is a subject of ongoing research. In this study, the influence of processing parameters on the structure-property relationships of synthesized Fe-Ni bimetallic catalysts and the yield of carbon nanotubes (CNTs) was investigated. The study also aimed to optimize the synthesis conditions for the Fe-Ni bimetallic catalyst supported on CaCO₃ and examine the effect of CNT purification on the final product. The CNTs were synthesized using a chemical vapor deposition process with an Fe-Ni bimetallic catalyst supported on CaCO₃, and the effects of processing parameters such as pre-calcination temperature, stirring speed, support mass, and pre-calcination time on the yield and properties of the CNTs were analyzed. The synthesized CNTs were then characterized using SEM, FT-IR, BET, XRD, and Raman spectrometers to assess their structure and properties. The study revealed that optimizing the synthesis conditions led to increased graphitization and crystallinity of the CNTs. A maximum CNT yield of 376% was obtained under the optimal conditions of a reaction temperature of 700°C, a time of reaction of 90 min, and nitrogen and C₂H₂ flow rates of 294 mL/min and 193 mL/min, respectively. CNT purification was found to be effective in reducing impurities and functionalizing the CNTs for easy dispersion. The findings provide valuable insights for the development of efficient methods for the large-scale production of high-quality CNTs.

Bioprospecting of microalgae as anticancer, antioxidant, and antidiabetic agents

Angga P. Asiandu, Widya Sari — Thu, 27 Jun 2024 00:00:00 +0700

Algae, either macroscopic or microscopic, often grow rapidly across diverse ecosystems. These organisms offer promising potential in the pharmaceutical and nutraceutical fields due to their valuable bioactive compounds such as astaxanthin, phycocyanin, stigmasterol, polysaccharides, steroids, and minerals. The bioactive compounds play a vital role in scavenging free radicals by binding to their molecules and targeting damaged cells. Additionally, some reports have highlighted the substantial anticancer activity of microalgae. Cancer, characterized by abnormal cell growth in tissues, bones, and blood, can be targeted through certain microalgal bioactive compounds that interact with p53 and Bcl2 proteins to induce apoptosis in the affected cells. Furthermore, microalgal secondary metabolites exhibit antidiabetic effects by stimulating insulin secretion in pancreatic beta cells, synthesizing insulin-like proteins, and mitigating insulin resistance. These microorganisms are potential sources for producing novel green therapeutic agents to combat degenerative diseases. Therefore, optimizing the application of microalgal biorefinery within the pharmaceutical industry is crucial.