A hydrogen peroxide biosensor based on nanoparticle PANI/HRP electrode

Recently, conducting polymers have attracted much interest in the development of biosensor. It contain π- electron backbone responsible for its unusual electronic properties such as electrical conductivity, low energy optical transitions, low ionization potential and high electron affinity. When the Horseradish peroxidase (HRP) was immobilized to the conducting polymers, these polymers possesses the ability to bind oppositely charged complex entities in their neutral insulating state. Determination of Hydrogen peroxide (H2O2) and other organic peroxides is of practical importance in clinical, environmental and many other fields. This study intends to see the role and properties of PANI/HRP layer towards H2O2 by measuring its current. Langmuir- Blodgett technique was used to form the PANI monolayer and the HRP was deposited in PANI monolayer by using electrodeposition method. Results from U.V.- visible spectrum of PANI with and without HRP shows two sharp absorption peaks at 320 nm and 720 nm. PANI forms as nanoparticles was revealed by VPSEM. AFM shows the image in roughness before and after the HRP was deposited on PANI monolayer. The current and response of H2O2 towards PANI/HRP electrode increases demonstrating effective electrocatalytic reduction of H202. PANI/HRP electrode not only act as excellent materials for rapid electron transfer but also for the fabrication of efficient biosensors

Penentuan kepekatan keradioaktifan radionuklid semula jadi dan indeks bahaya sinaran pada musim hujan dari tanah di kawasan sekitar kemudahan simpanan jangka panjang (LTSF) Bukit Kledang, Perak

Kajian dan pemantauan yang dilakukan terhadap taburan dan penentuan aktiviti keradioaktifan radionuklid semula jadi boleh dijadikan panduan dan rujukan serta amat berguna terutamanya ketika berlakunya dedahan sinaran yang tinggi dan tidak terancang daripada sumber antropogenik dan kemalangan nuklear global. Sampel tanah permukaan dari 12 lokasi yang telah dikenal pasti di sekitar kawasan kemudahan repositori telah diambil untuk dijalankan kajian analisis penentuan kepekatan keradioaktifan dan indeks bahaya sinaran. Pengukuran kepekatan radioaktif dalam sampel tanah dilakukan dengan menggunakan sistem pembilangan spektrometer gama yang dilengkapi dengan pengesan High Purity Germanium (HPGe). Keputusan yang diperoleh menunjukkan kepekatan radioaktiviti 238U adalah berjulat antara 17.83 - 31.80 Bq kg-1, 234Th adalah berjulat antara 23.18 - 40.64 Bq kg-1, 226Ra adalah berjulat antara 20.09 -32.80 Bq kg-1, 228Ra adalah berjulat antara 21.20 - 38.88 Bq kg-1 dan 40K adalah berjulat antara 9.11 - 51.39 Bq kg-1 dengan nilai purata masing-masing adalah 21.45 Bq kg-1, 28.17 Bq kg-1, 24.00 Bq kg-1, 27.43 Bq kg-1 dan 24.01 Bq kg-1. Nilai kepekatan radioaktiviti radionuklid tersebut didapati setara dengan nilai yang pernah dilaporkan dalam kajian terdahulu di Semenanjung Malaysia. Nilai purata yang diperoleh bagi keempat-empat parameter Indeks Bahaya Radiasi iaitu aktiviti bersamaan radium (Raeq), kadar dos luaran (D), dos berkesan tahunan dan indeks bahaya luaran (Hex) masing-masing adalah 66.37 Bq kg-1, 29.13 nGy j-1, 20.16 μSv dan 0.18. Nilai yang diperoleh ini adalah rendah berbanding nilai purata dunia dan nilai piawaian yang diguna pakai secara global iaitu masing-masing adalah 370 Bq kg-1, 57nGy j-1, 480.00 μSv dan 1.0. Perbandingan dengan kajian sebelum ini juga mendapati nilai bagi keempat-empat parameter adalah rendah dan setara. Ini menunjukkan tahap bahaya radiasi di kawasan sekitar kajian adalah selamat untuk orang ramai

Halo structure investigation of nucleus 8He via core deformation parameter

Helium-8 (8He) is a four neutrons halo nucleus and is the halo nucleus that attract attention to observe because it belongs to the group of light dripline nuclei. We studied the two neutrons halo nucleus of 8He. This halo nucleus lies on the neutron rich dripline in the nuclear landscape. Nucleus 8He was investigated in the Three-body Model with two different configurations (T and Y). To describe the Three-body Model, Jacobi coordinate systems for few bodies was used for this hyper-nucleus (8He). In this study, core (6He) + two valence neutrons (n + n) were considered as the Three-body. Based on the finding, theoretical data on configuration Y met a good agreement with the experimental data of binding energy and rms matter radius. While for configuration T, the data slightly differ from the experimental data. The results showed that the core deformation parameters, β2 of 8He were 0.12, 0.19, 0.35, 0.40, and 0.47. The binding energies -3.112 MeV, -3.416 MeV, and -3.625 MeV were calculated for the deformation parameters 0.35, 0.40, and 0.47 and rms radii 2.032 fm, 2.305 fm, and 2.39 fm were found for the deformation parameters 0.19, 0.35, and 0.4, respectively. In conclusion, 8He exhibits in prolate due to positive values of core deformation parameters

Determination of uranium internal dose exposure through soil digestion using RDRC and URODC software

This study was conducted to determine the dose of internal exposure through ingestion of soil in the vicinity of the repository facility in Bukit Kledang, Ipoh, Perak. Data from this study can assess the risk of radiation exposure to the health of local population, specifically blood, liver and bone cancers. Activities of radionuclide 238U in MG and M10 in the gastric phase are 1.118 ± 0.062 and 1.232 ± 0.073 Bq/kg, while the respective activities in the gastrointestinal phase are 0.553 ± 0.051 and 0.905 ± 0.082 Bq/kg. Samples of M10 recorded the highest reading of internal exposure in both phases. Digestion of 2 g soil from M10 samples on gastric phase generated the annual effective dose of 3.168 μSv/year with an assessment of cancer risk by 0.001% within 70 years to public. Organ dose for blood, liver and bone were 0.59, 11.60 and 65.95 μSv, respectively. Analysis of organ doses based on the concentration of 238U found that M10 has higher dose compared to MG. Risk assessment predicted for 70 years after the ingestion of the soil for blood cancer was 0.003% and liver cancer was 0.004% while the highest cancer risk was for bone cancer with 0.023%. Although the concentration of specific activity of 238U identified is low, it is shown that the internal dose exposure as a result of digestion of radionuclides are below the standard and can be considered as safe for public

A study on the atmospheric dispersion of radionuclide released from TRIGA MARK II reactor using gaussian plume model

TRIGA MARK II reactor is a research facility and site for neutron activation analysis. Should there be fuel rod damage for the first time, amongst its possible causes are human and environmental factor. Consequently, the study objectives were to determine types and released rates of radionuclides dispersed to air and deposited on land through core inventory using ORIGEN2 Code; to determine the concentrations of radionuclides released to air and deposited on land using Gaussian Plume Model; and to determine the exposure doses of radionuclides released to air and deposited on land using exposure dose equation. Core inventory identified types of radionuclides which were Br, I, Kr and Xe. The chosen radioisotopes of Br-83, I-131, Kr-85 and Xe-135 were based on its negative impact on human body system. The maximum released rate of Br-83 was 0.522×105 Bq/s; I-131 was 2.818×105 Bq/s; Kr-85 was 6.447×105 Bq/s and Xe-135 was 4.850×105 Bq/s, respectively. The maximum concentration in the atmosphere for Br-83 was 1.981 Bq/m3; I-131 was 0.062 Bq/m3; Kr-85 was 25.034 Bq/m3 and Xe-135 was 4.248 Bq/m3. The annual exposure doses for four selected radionuclides were 1326 μSv/yr (300 m), 119 μSv/yr (1000 m) and 7.463 μSv/yr (4000 m) for Category B, whereas for Category were 194 μSv/yr (300 m), 17.440 μSv/yr (1000 m) and 1.090 μSv/yr (4000 m), respectively. Conclusively, this study shows that in case of fuel rod damage on TRIGA MARK II reactor, radionuclide atmospheric dispersion at a distance of 300 m (Category B) was exceeding the standard annual exposure dose limit (1000 μSv/yr)

Penilaian kualiti air bawah tanah di Kelantan dan Pahang, Malaysia

Air bawah tanah yang menjadi sumber kegunaan domestik kepada pengguna memerlukan penilaian air bawah tanah bagi mengelakkan berlakunya isu kesihatan. Kajian ini dijalankan untuk menilai kualiti air telaga tiub dalam aspek kandungan logam berat, bahan radioaktif semula jadi (NORM) dan bakteria patogen di Kelantan dan Pahang, Malaysia. Hasil kajian ini menunjukkan kandungan Fe (90-42100 µg/L) dan Mn (3-478 µg/L) yang diperoleh adalah tinggi dan boleh menjejaskan kualiti air secara keseluruhan. Kandungan NORM yang terkandung dalam air telaga adalah 0.02-0.08 Bq/L bagi jumlah pengaktifan Alpha dan 0.02-0.15 Bq/L bagi jumlah pengaktifan beta, yang berada di bawah paras selamat yang telah ditetapkan oleh WHO. Kandungan NORM dalam sampel tanah adalah dalam julat 401-1348 Bq/kg untuk 40K, 19-175 Bq/kg untuk 232Th dan 28-318 Bq/kg untuk 238U yang boleh diterima di Malaysia. Anggaran dos sinaran tahunan adalah antara 52 µSv/tahun hingga 379 µSv/tahun dan berada dalam julat selamat untuk orang ramai. Kesemua sampel air dari Kelantan dan dua sampel air dari Pahang mengandungi bakteria enteropatogen terutamanya Escherichia coli dan Salmonella sp. yang melebihi piawaian Kualiti Air Kebangsaan. Boleh disimpulkan bahawa kualiti air bawah tanah selamat untuk digunakan semasa kecemasan, tetapi ia perlu dirawat sebelum diminum

Radiological impact assessment of fukushima daiichi nuclear accident on Malaysian Marine biotas via Ocean Partway using Erica Code System

Fukushima Daiichi nuclear disaster led to radioactive contamination crisis was resulted from a series of system failures, nuclear meltdown and radioactive material releases, following the 9.0 magnitude of earthquake and tsunami on March 11, 2011. The objectives of this study were; to investigate the movement of radionuclides based on oceanography and morphology of Pacific Ocean and Southeast Asia (Malaysia); to estimate the time for radionuclides to reach Malaysia and to calculate the amount of total absorbed dose rate for selected marine biotas namely benthic fish and pelagic fish. ERICA code system was used because it has the ERICA integrated approach to assess the radiation risk of biota. The estimations of radionuclide discharge from Fukushima Daiichi nuclear disaster were based on Cs-137 (half-life of 30.17 years), I-131 (half-life of 0.02 years). The parameters such as discharge rate of radionuclides (Bq/s), water depth (m), the distance between the target coast of Malaysia and radionuclide release point (m), the distance between the receptor and radionuclide release (m) and the velocity of the water/ocean currents (m/s) were studied. The results showed that the minimum estimated arrival time of radionuclides to reach Malaysia is located in Sandakan, Sabah, which is approximated at 4.82 years (Dec 2015) with an average of 5.039±0.310 years after the accident. Meanwhile, maximum estimated arrival time of radionuclides to Malacca is 5.87 years (Jan 2017) with an average of 5.527±0.480 years. The lowest estimated total absorbed dose rate by benthic fish is 0.0583 μGy/h with an average of (6.33±0.71) × 10-2 μGy/h in Malacca whereas the highest estimated total absorbed dose rate by benthic fish is 0.0751 μGy/h with an average of (7.11±0.57) × 10-2 μGy/h in Sandakan, Sabah. Pelagic fish in Malacca shows the lowest estimated total absorbed dose rate of 0.00149 μGy/h with an average of (1.62±0.18) × 10-3 μGy/h whereas Sandakan, Sabah showed the highest estimated total absorbed dose rate of 0.00193 μGy/h with an average of (1.83±0.15) × 10-3 μGy/h. The total absorbed dose rate and risk quotient of ERICA code system show that for all reference organisms, the probability of exceeding the selected screening dose rate of 400 μGy/h by aquatic biota is below the probability selected. Therefore, no measurable population of chronic exposure effects would occur at this stage. Nonetheless, a normal experimental analysis of fish samples should be performed in order to monitor the radiation effects to marine ecosystem

Determination of trace elements in epiphytic lichens from Bandar Baru Bangi, Selangor using INAA method

Lichens have been used as effective biomonitors of atmospheric pollutants as they can take up nutrients and pollutants directly from the atmosphere. In this study, trace element contents in epiphytic lichens were determined using INAA method. Samples were collected from 7 sampling locations around Bandar Baru Bangi, Selangor. The elements detected were As (1.73±0.85 mg/kg), Ce (3.65±1.91 mg/kg), Co (0.29±0.12 mg/kg), Cr (5.92±3.54 mg/kg), Cs (0.92±0.25 mg/kg), Eu (0.03±0.02 mg/kg), Fe (1280±760 mg/kg), Hf (0.37±0.18 mg/kg), La (1.52±0.89 mg/kg), Rb (27.7±4.8 mg/kg), Sc (0.33±0.19 mg/kg), Sm (0.28±0.16 mg/kg), Th (1.21±0.62 mg/kg) and Zn (116±27 mg/kg). Comparisons were then made between the elemental concentrations obtained and the baseline data from literature. Results showed that most of the elements were within the concentration range of the baseline data. Enrichment factors (EF) of the trace element in lichens showed that most of the elements were within the range of the baseline data except for As which was found to be slightly enriched (EF: 13.2 - 28.5). Regression analysis indicated significant correlation (p<0.05) with Sc for most of the elements which signifies crustal input except for Cs and Rb. The poor correlations of Cs and Rb with Sc may be due to the mobility of these elements. In summary, trace element data obtained using INAA were very useful and demonstrated that lichens were suitable biomonitors for identifying potential trace element pollutants in ambient air around the sampling area

Study of non-1/v reaction nuclides using k0 – neutron activation analysis at the Malaysian Nuclear Agency research reactor (Kajian tindak balas Nuklid yang tidak mematuhi hukum 1/ν menggunakan k 0- analisis pengaktifan neutron di Reaktor Penyelidikan Agensi Nuklear Malaysia)

The modified spectral index r(α); the Westcott gLu(Tn) factor and absolute neutron temperature Tn were determined for the handling of non-1/ν (n, γ) reaction based on the Westcott formalism using k0-neutron activation analysis (k0-NAA) method at the Malaysian Nuclear Agency (MNA) research reactor. The r(α) was determined by the bare bi-isotopic monitor method using measurement of radionuclides of 97Zr and 95Zr. The 176Lu as non-1/ν and 197Au as 1/ν monitors were utilized for determination of gLu(Tn). The r(α) and gLu(Tn) values ranged from 0.0715 to 0.1417 with a RSD of 15.24% and from 1.7832 to 2.0149 with a RSD of 3.58%, respectively. The accuracy of the method was evaluated based on the calculated absolute neutron temperature (Tn) value. The calculated average value of Tn was 40.56±9.32°C while the value reported by MNA was 40°C, which represents an acceptable level of consistency

Microscopic study of AOT and CTAB anionic-rich catanionic phase

Catanionic system using anionic sodium bis-(2ethylhexyl)sulfosuccinate (AOT) and cationic cetyltrimethylammonium bromide (CTAB) is studied. The system is prepared by addition of CTAB solution to a prepared AOT solution until slight anionic-rich catanionic phase is produced. Catanionic system consists of the mixture of different types of surfactants and counterion due to electrostatic interaction between the oppositely charged surfactant. Both of these products affect the in surface activity of the surfactant. Hydrodynamic diameters decrease and clearer solution were seen with the increase of CTAB concentration in solution mixture. As a result, mixed surfactant with larger hydrophobic region and the presence of counterion will induce smaller vesicle to form in catanionic system