Journal of the Sri Lanka Association for the Advancement of Science

Effect of CT Simulator Tube Voltages on CT Number and Relative Electron Density of CT Images

Fri, 31 May 2024 00:00:00 +0000

The radiotherapy treatment planning for the cancer patient begins with the imaging of the patient using a Computed Tomography (CT) simulator. The CT simulator determines the locations and densities of patient organs using pixels. Each pixel has a unit called a CT number, or Hounsfield Unit (HU), to express the quantity of radiation attenuation in patient tissues. The density of human tissue is presented in Relative Electron Density (RED). The conversion relationship between RED and CT numbers is required to be determined and fed to the Treatment Planning System (TPS). The TPS calculates the radiotherapy dose for the patient using this CT-RED conversion curve. Most TPSs contain a single CT-RED curve defined at a specific CT tube voltage.

In this research, we studied the effect of CT tube voltages using a CT simulator (GE; CT-RED curve defined at 140kV) at Teaching Hospital Karapitiya, which provides step voltages of 80 kV, 120 kV, and 140 kV, XIO TPS, and Thorax Phantom (CIRS) containing 5 tissue types. According to the measured results, CT numbers decrease with increasing CT Tube voltage. Also, there were no significant errors in RED values of tissues at 120 kV, with respect to the 140 kV. But there were 5.55%, 2.10%, 0.99%, 0.99%, 0.95%, and 1.34% errors in RED for lung, adipose, water, T1420, muscle, and bone tissues respectively at 80kV with respect to 140 kV.

Key Words: Radiotherapy, CT imaging, CT Number, CT tube voltage, Relative Electron Density

Incorporation of Wood ash and waste glass powder in enhancing concrete block performance

Fri, 31 May 2024 00:00:00 +0000

This study explores the feasibility of utilizing wood ash and waste glass powder as sustainable alternatives in the production of concrete blocks, aiming to address environmental concerns and enhance durability in construction. Cement blocks with varying percentages of wood ash (ranging from 10% to 25%) and a consistent 10% substitution of fine aggregates with waste glass powder were investigated. Six sample sets, including standard blocks, underwent testing for compressive strength, water absorption, and heat release at 7, 14, and 21 days of curing. Results demonstrate that a 15% wood ash replacement significantly improves compressive strength and reduces water absorption after 21 days. Furthermore, the combination of 15% wood ash with 10% glass powder replacement yields cement blocks with superior properties. The integration of wood ash with waste glass powder further enhances the performance of concrete blocks. By incorporating these materials into concrete block production, significant steps can be made towards reducing environmental impact and promoting sustainability within the construction industry.

Key Words: wood ash, waste glass powder, eco-friendly, concrete blocks, compressive strength

Low-Pressure and Atmospheric-Pressure Cold Plasma Treatment as a Pretreatment for Extracting Volatile Oils from Black Pepper (Piper nigrum) Seeds

P. Neville Rohitha Jayashantha Amunugoda, Gayathri, Hasitha, Sanja, Ajith — Fri, 31 May 2024 00:00:00 +0000

Volatile Oils (VOs) are essential contributors to the aroma and flavor of black pepper seeds, making their analysis crucial after sterilization processes. This study aimed to qualitatively and quantitatively analyze VOs in black pepper seeds that have been subjected to the following two modes of Cold Plasma (CP) treatments to evaluate its efficacy as a pretreatment for hydro distillation. CP generating setups, Low-Pressure Cold Plasma (LPCP) and Gliding Arc Plasma Discharge (GAPD) were used for the study. A commercially available black pepper (Piper nigrum)variety (MB12) underwent CP treatments with varying time durations (5, 10, and 15 minutes). The VOs were extracted using hydro-distillation and identified and quantified by GC-MS and GC-FID respectively. The study examined 12 major components of VOs, including α-pinene, β-caryophyllene, and D-limonene. Results revealed that LPCP at 5 minutes and GAPD at 10 minutes yielded the highest VO content, while prolonged treatment times led to decrease oil yields in both treatments. No significant differences were observed in individual VO components between the two CP treatments. The refractive index of VOs after LPCP and GAPD treatments did not significantly differ, affirming the GC-FID results. Importantly, the study concluded that both 5-minute treatment time of LPCP and10-minute treatment time of GAPD did not adversely affect the quality of VOs in black pepper seeds. The results of the study highlighted the necessity of insights into optimal processing conditions and highlighting the utility of LPCP and GAPDas pretreatments for VO extraction.

Keywords: black pepper seeds, volatile oils extraction, cold plasma, gliding arc plasma, low pressure plasma

Photocatalytic degradation of methylene blue dye using silver nanoparticles prepared from Raphanus sativus

Fri, 31 May 2024 00:00:00 +0000

Green synthesis of silver nanoparticles possesses many merits compared to that of chemical synthetic methods. Silver nanoparticles have been widely used in many applications such as catalytic activity, dye degradation, antimicrobial and anti-inflammatory activities. In this study silver nanoparticles (AgNps) were synthesized using extract of Raphanus sativus roots and identified by the UV-Visible spectrophotometer. XRD peaks of the crystal confirmed the face-centered cubic silver crystals with size of 49.16 nm. FT-IR spectrum indicated the functional groups on this nanoparticles. Scanning electron microscope images showed the spherical shapes and size of the AgNps. The photocatalytic degradation of methylene blue was performed by altering the weight of silver nanoparticles and moles of NaBH₄. The degradation mixtures of 5 mg AgNps and 5mL of NaBH₄, 10 mg AgNps and 5 mL of NaBH₄ and 10 mg AgNps and 10 mL of NaBH₄ attain degradation of 5.088%, 83.86 % and 48.067% of the methylene blue respectively. This study revealed that green synthesized silver nanoparticles from the extract of Raphanus sativus can act as a photocatalytic dye degradation agent against methylene blue.

Key words: Green synthesis, AgNPs, XRD, dye degradation, methylene blue