Displaying publications 81 - 100 of 392 in total

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  1. Measurement of ²³⁸U,²³²Th and ⁴⁰K in boreholes at Gosa and Lugbe, Abuja, north central Nigeria
    Maxwell O, Wagiran H, Ibrahim N, Lee SK, Sabri S
    Radiat Prot Dosimetry, 2013 Dec;157(2):271-7.
    PMID: 23754832 DOI: 10.1093/rpd/nct140
    The purpose of this project is to evaluate the suitability of different sites as locations for obtaining underground water for consumption. The analysis of ²³⁸U, ²³²Th and ⁴⁰K from rock samples from each layer of borehole at a depth of ∼50 m at Site A borehole, S3L1-S3L6 in Gosa and 40 m at Site B borehole, S4L1-S4L5 in Lugbe, Abuja, north central Nigeria is presented. The gamma-ray spectrometry was carried out using a high-purity germanium detector coupled to a computer-based high-resolution multichannel analyzer. The activity concentrations at Site A borehole for ²³⁸U have a mean value of 26 ± 3, ranging from 23 ± 2 to 30 ± 3 Bq kg⁻¹, ²³²Th a mean value of 63 ± 5, ranging from 48 ± 4 to 76 ± 6 Bq kg⁻¹ and ⁴⁰K a mean value of 573 ± 72, ranging from 437 ± 56 to 821 ± 60 Bq kg⁻¹. The activity concentrations at Site B borehole for ²³⁸U have a mean value of 20 ± 2, ranging from 16 ± 2 to 23 ± 2 Bq kg⁻¹, ²³²Th a mean value of 46 ± 4, ranging from 43 ± 4 to 49 ± 4 Bq kg⁻¹, ⁴⁰K a mean value of 915 ± 116 and ranging from 817 ± 103 Bq kg⁻¹ to 1011 ± 128 Bq kg⁻¹. It is noted that the higher activity concentrations of ²³²Th and ²³⁸U are found in Site A at Gosa. Site B has lower radioactivity, and it is recommended that both sites are suitable for underground water consumption.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  2. The presence of natural radioactivity and 137Cs in the South China Sea bordering peninsular Malaysia
    Amin YM, Mahat RH, Nor RM, Khandaker MU, Takleef GH, Bradley DA
    Radiat Prot Dosimetry, 2013 Oct;156(4):475-80.
    PMID: 23584496 DOI: 10.1093/rpd/nct097
    The presence of natural radioactivity and (137)Cs has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tōhoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring (226)Ra, (228)Ra and primordial (40)K, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(-1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(-1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of (137)Cs. The activity of (137)Cs varied from ND to 0.5 Bq kg(-1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  3. Radiometric analysis of construction materials using HPGe gamma-ray spectrometry
    Khandaker MU, Jojo PJ, Kassim HA, Amin YM
    Radiat Prot Dosimetry, 2012 Nov;152(1-3):33-7.
    PMID: 22887119 DOI: 10.1093/rpd/ncs145
    Concentrations of primordial radionuclides in common construction materials collected from the south-west coastal region of India were determined using a high-purity germanium gamma-ray spectrometer. Average specific activities (Bq kg(-1)) for (238)U((226)Ra) in cement, brick, soil and stone samples were obtained as 54 ± 13, 21 ± 4, 50 ± 12 and 46 ± 8, respectively. Respective values of (232)Th were obtained as 65 ± 10, 21 ± 3, 58 ± 10 and 57 ± 12. Concentrations of (40)K radionuclide in cement, brick, soil and stone samples were found to be 440 ± 91, 290 ± 20, 380 ± 61 and 432 ± 64, respectively. To evaluate the radiological hazards, radium equivalent activity, various hazard indices, absorbed dose rate and annual effective dose have been calculated, and compared with the literature values. Obtained data could be used as reference information to assess any radiological contamination due to construction materials in future.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  4. Thermoluminescence properties of Li2CO3-K2CO3-H3BO3glass system co-doped with CuO and MgO
    Alajerami YS, Hashim S, Ramli AT, Saleh MA, Kadni T
    Radiat Prot Dosimetry, 2013 Jun;155(1):1-10.
    PMID: 23193136 DOI: 10.1093/rpd/ncs310
    The thermoluminescent properties of boric glass modified with lithium and potassium carbonates (LKB) and co-doped with CuO and MgO are reported for the first time. Two techniques are applied to investigate the effect of dopants and co-dopants on the thermal stimulation properties of LKB. The induced TL glow curves of a CuO-doped sample are found to be at 220°C with a single peak. An enhancement of about three times is shown with the increment of 0.1 mol % MgO as a co-dopant impurity. This enhancement may contribute to the ability of magnesium to create extra electron traps and consequently the energy transfer to monovalent Cu(+) ions. LKB:Cu,Mg is low Z material (Zeff=8.55), and observed 15 times less sensitive than LiF: Mg, Ti (TLD-100). The proposed dosemeter showed good linearity in TL dose-response, low fading and excellent reproducibility with a simple glow curve, and thus, can be used in the radiation dosimetry.
    Matched MeSH terms: Potassium/chemistry*
  5. NATURAL RADIONUCLIDES IN SOIL AND ROOT VEGETABLES IN MALAYSIA: TRANSFER FACTORS AND DOSE ESTIMATES
    Al Mutairi AMM, Kabir NA
    Radiat Prot Dosimetry, 2020 Jun 12;188(1):47-55.
    PMID: 31711202 DOI: 10.1093/rpd/ncz256
    Tapioca and sweet potato are the fourth and fifth most consumed crops in Malaysia. The activity concentrations of natural radionuclides in these vegetables were assessed from two regions in Malaysia (Kedah and Penang) along with soil samples using gamma ray spectroscopy. The transfer factors of 226Ra, 232Th and 40K from soil to vegetables were calculated, and a dose assessment was performed. The activity concentrations of 226Ra, 232Th and 40K in soil samples did not show a significant variation with the regions investigated, and the average values obtained, in Bq/kg, (±SD) were as follows: 80 ± 41, 56 ± 12, 516 ± 119, respectively. The respective average activity concentrations in vegetables were as follows, in Bq/kg: (±SD) 2.0 ± 0.5, 6 ± 2, 153 ± 49. The corresponding transfer factors were calculated to be 0.03, 0.11 and 0.31 for 226Ra, 232Th and 40K, respectively. The average annual effective doses due to the exposure from soil and ingestion of vegetables were found to lie within the worldwide ranges.
    Matched MeSH terms: Potassium Radioisotopes
  6. TERRESTRIAL RADIONUCLIDES IN SURFACE (DAM) WATER AND CONCOMITANT DOSE IN METROPOLITAN KUALA LUMPUR
    Khandaker MU, Uwatse OB, Bin Shamsul Khairi KA, Faruque MRI, Bradley DA
    Radiat Prot Dosimetry, 2019 Dec 31;185(3):343-350.
    PMID: 30806465 DOI: 10.1093/rpd/ncz018
    Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe γ-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l-1, have been found to be in the range 2.4-3.2 for 226Ra, 1.1-1.3 for 232Th and 22.7-40.7 for 40K, in line with literature data for surface waters. The total annual ingestion dose for infants (<1 y) and adolescents (12-17 y) are found to be significant and greater than the World Health Organization recommended maximum dose of 0.1 mSv y-1 from the imbibing of drinking water. However, the Dam water does not pose a threat to public health, the Dam water not being used as the sole source of drinking water. Noting that this is the only known study of water from Batu Dam, the reported levels allow for evaluation of future changes in the natural radioactivity profile.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  7. RADIATION DOSE TO MALDIVIANS VIA THE CONSUMPTION OF TUNA FISH CAUGHT FROM THE COASTAL WATERS OF INDIAN OCEAN
    Nadhiya A, Khandaker MU, Mahmud S, Yarima MH
    Radiat Prot Dosimetry, 2019 Oct 01;184(3-4):302-306.
    PMID: 31034553 DOI: 10.1093/rpd/ncz085
    Recognising the consumption of tuna fish as a major foodstuff in Maldivian diet, the presence of naturally occurring radionuclides in Yellowfin and Skipjack tuna are determined by using HPGe gamma-ray spectrometry to evaluate the health hazards to Maldivians. The samples were collected from different atolls of Maldives adjacent to the coastal waters of Indian Ocean. The activity concentrations (Bq kg-1) in Yellowfin tuna for 226Ra, 232Th and 40K are in the ranges of 4.2 ± 1.8-10.5 ± 1.1, 1.3 ± 0.3-3.2 ± 0.7 and 589 ± 29-697 ± 34, respectively while in Skipjack tuna the respective ranges are 3.9 ± 0.5-13.2 ± 1.1, 1.3 ± 0.3-2.7 ± 0.6 and 511 ± 28-681 ± 35. The committed effective dose (mean 263 μSv y-1) received by an individual due to the dietary intake of Yellowfin tuna falling below the UNSCEAR referenced global internal dose limit of 290 μSv y-1; while for Skipjack tuna, the estimated dose (mean 365 μSv y-1) exceeds the world average limiting value. The carcinogenic risk was found to be well below the ICRP referenced acceptable limit of 2.5 × 10-3. The present study indicates that the radiation dose to Maldivian via the consumption of Yellowfin tuna poses an insignificant threat to the public health. However, prolonged consumption of Skipjack tuna fish from the studied areas may pose a cumulative risk to the public health.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  8. ASSESSMENT OF NATURALLY OCCURRING RADIONUCLIDES IN MALAYSIA'S BUILDING MATERIALS
    Abdullahi S, Ismail AF, Samat S
    Radiat Prot Dosimetry, 2019 Dec 31;186(4):520-523.
    PMID: 31034551 DOI: 10.1093/rpd/ncz125
    The activity concentrations of 226Ra, 232Th and 40K radionuclides from common building materials used by Malaysian people for construction purposes were studied using High-Purity Germanium (HPGe) detector. The measured activity concentrations of the aforementioned radionuclides range from 10 ± 1 Bq kg-1 (limestone) to 155 ± 61 Bq kg-1 (feldspar), 12 ± 3 Bq kg-1 (limestone) to 274 ± 8 Bq kg-1 (kaolin) and 62 ± 19 Bq kg-1 (limestone) to 1114 ± 20 Bq kg-1 (pottery stone) for 226Ra, 232Th and 40K, respectively. The measured activity concentrations of the natural radionuclides reported herein were found to be in accordance with other previous studies. In general, the activity concentration of the natural radionuclides revealed that all the determined values were below the recommended limit.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  9. A STUDY OF NATURAL RADIOACTIVITY IN SOME BUILDING MATERIALS IN NIGERIA
    Maxwell O, Emmanuel JS, Olusegun AO, Cyril EO, Ifeanyi AT, Embong Z
    Radiat Prot Dosimetry, 2019 May 01;183(3):332-335.
    PMID: 30085254 DOI: 10.1093/rpd/ncy121
    Building materials of different brands were assessed for the concentrations of 226Ra, 232Th and 40K using HPGe detector. The activity concentrations in the measured samples ranged from 27 ± 8 to 82 ± 8 Bq kg-1 for 226Ra, 41 ± 4 to 101 ± 8 Bq kg-1 for 232Th and 140 ± 8 to 940 ± 19 Bq kg-1 for 40K, respectively. The Radium equivalent (Raeq) activity from the samples was found to be <370 Bq kg-1 as the recommended value for construction materials. This study will set a baseline data for significant standards on radiation exposure of the measured radionuclides in the selected building materials used in Nigeria.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  10. ASSESSMENT OF NATURAL RADIOACTIVITY IN MAIZE AND ESTIMATION OF CONCOMITANT DOSE TO NIGERIAN VIA INGESTION PATHWAY
    Yarima MH, Khandaker MU, Nadhiya A, Olatunji MA
    Radiat Prot Dosimetry, 2019 Oct 01;184(3-4):359-362.
    PMID: 31089715 DOI: 10.1093/rpd/ncz115
    Uranium, thorium and potassium are the most abundant naturally occurring radioactive materials (NORMs) found in soils and other environmental media including foodstuffs. Since the human exposures to NORMs is an unavoidable phenomenon, in such a way that they can easily find their way to human being via food chain, detailed knowledge on their presence in foodstuffs is necessary to assess the radiation dose to the population. Thus, the present study concerns the assessment of natural radioactivity in maize, a staple foodstuff for Nigerian, via HPGe gamma-ray spectrometry. Activity concentrations (Bq/kg) in the maize samples were found to be in the range of 6.1 ± 0.6-8.2 ± 1.3, 2.2 ± 0.4-5.1 ± 0.7 and 288 ± 16-401 ± 24 for 226Ra, 232Th and 40K, respectively. Measured data for 226Ra and 232Th show below the world average values of 67 Bq/kg and 82 Bq/kg, respectively, while the activity of 40K exceeds the global average of 310 Bq/kg. The annual effective dose via the maize consumption was found to be far below the UNSCEAR recommended ingestion dose limit of 290 μSv/y, and the estimated lifetime cancer risk show lower than the ICRP (1991) cancer risk factor of 2.5 × 10-3 based on the additional annual dose limit of 1 mSv for general public, thus pose no adverse health risk to the Nigerian populace.
    Matched MeSH terms: Potassium Radioisotopes/analysis*
  11. Norm in cultivated honey in Malaysia and concomitant effective dose to consumers
    Khandaker MU, Zayadi NSB, Sani SFA, Bradley DA, Osman H, Alzamil Y, et al.
    Radiat Prot Dosimetry, 2023 Nov 02;199(18):2174-2178.
    PMID: 37934995 DOI: 10.1093/rpd/ncad179
    Present study concerns the radiological character of Malaysian honey. A total of 18 samples (representative of the various most common types) were obtained from various honey bee farms throughout the country. Using a high-purity germanium γ-ray spectroscopic system, the samples were analysed for the naturally occurring radionuclides 226Ra, 228Ra and 40K. The respective range of activities (in Bq/kg) was: 3.49 ± 0.35 to 4.51 ± 0.39, 0.99 ± 0.37 to 1.74 ± 0.39 and 41.37 ± 3.26 to 105.02 ± 6.91. The estimated associated committed effective doses were derived from prevailing data on national consumption of honey, the annual dose being found low compared with the UNSCEAR reference dose limit of 290 μSv y-1. The estimated threshold consumption rate for honey indicates a maximum intake of 339 g/d, which poses an insignificant radiological risk to public health; however, the total dietary exposure may not, the guidance level of 290 μSv y-1 being applicable to dietary intake of all foodstuffs. The study is in support of the cultivation of a healthy lifestyle, acknowledging prevailing radioactivity within the environment.
    Matched MeSH terms: Potassium Radioisotopes/analysis
  12. The status of natural radioactivity in Nigerian environments
    Olatunji MA, Khandaker MU, Nwankwo VUJ, Idris AM
    Radiat Environ Biophys, 2022 Nov;61(4):597-608.
    PMID: 36175773 DOI: 10.1007/s00411-022-00993-3
    Proper documentation of baseline radiation data of different environments is an important step toward adequate environmental monitoring, and it provides quick means to quantitatively check and determine possible radionuclide contamination by anthropogenic sources. Besides, such documentation is useful for decision making processes, assessment of dose rates to the public, epidemiological studies, and environmental regulations. This review summarizes the results of studies conducted on radioactivity in Nigerian environments. For most soil samples, the levels of radioactivity are well within the world averages of 33, 45, and 420 Bq kg-1 for 226Ra, 232Th and 40K, respectively. Other soil samples from regions such as Abeokuta in the southwest, and Jos in the northcentral have been described as high background radiation areas with radioactivity values comparable with those obtained from known high background radiation areas such as the Odisha (formerly Orissa) coast in India (with values reported as 350, 2,825, and 180 Bq kg-1 for 238U/226Ra, 232Th, and 40K, respectively). In some parts of Nigeria, surface and underground water sources used for drinking and other purposes also present elevated levels of 226Ra above the world range of 0.01 to 0.1 Bq l-1 and the tolerable levels recommended by the World Health Organization and U.S. Environmental Protection Agency. Corresponding radiation doses due to measured radioactivities from different environments were estimated and compared with those reported in similar studies around the world. More so, the human and environmental health hazards that might be associated with the reported radioactivity in different environmental settings are discussed. The present report is expected to support authorities in developing appropriate regulations to protect the public from radiation exposure arising from environmental radioactivity. The report also examines other areas of consideration for future studies to ensure adequate radiation monitoring in Nigeria.
    Matched MeSH terms: Potassium Radioisotopes/analysis
  13. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application
    Reshak AH, Shahimin MM, Shaari S, Johan N
    Prog Biophys Mol Biol, 2013 Nov;113(2):327-32.
    PMID: 24139943 DOI: 10.1016/j.pbiomolbio.2013.10.002
    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
    Matched MeSH terms: Potassium Compounds/chemistry
  14. Bioseparation of phycocyanin from Phormidium tergestinum using an aqueous two-phase system
    Tan JS, Abbasiliasi S, Lalung J, Tam YJ, Murugan P, Lee CK
    Prep Biochem Biotechnol, 2021;51(3):260-266.
    PMID: 32876520 DOI: 10.1080/10826068.2020.1808793
    This study aimed at purification of phycocyanin (PC) from Phormidium tergestinum using an aqueous two-phase system (ATPS) comprised of polyethylene glycol (PEG) and salts. The partitioning efficiency of PC in ATPS and the effect of phase composition, pH, crude loading, and neutral salts on purification factor and yield were investigated. Results showed that PC was selectively partitioned toward bottom phase of the system containing potassium phosphate. Under optimum conditions of 20% (w/w) PEG 4000, 10% (w/w) potassium phosphate, 20% (v/v) crude load at pH 7, with addition of 0.5% (w/w) NaCl, PC from P. tergestinum was partially purified up to 5.34-fold with a yield of 87.8%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the molecular weight of PC was ∼19 kDa. Results from this study demonstrated ATPS could be used as a potential approach for the purification of PC from P. tergestinum.
    Matched MeSH terms: Potassium Compounds/chemistry
  15. Fulltext Evaluation of the cardiotoxicity of mitragynine and its analogues using human induced pluripotent stem cell-derived cardiomyocytes
    Lu J, Wei H, Wu J, Jamil MF, Tan ML, Adenan MI, et al.
    PLoS One, 2014;9(12):e115648.
    PMID: 25535742 DOI: 10.1371/journal.pone.0115648
    INTRODUCTION: Mitragynine is a major bioactive compound of Kratom, which is derived from the leave extracts of Mitragyna speciosa Korth or Mitragyna speciosa (M. speciosa), a medicinal plant from South East Asia used legally in many countries as stimulant with opioid-like effects for the treatment of chronic pain and opioid-withdrawal symptoms. Fatal incidents with Mitragynine have been associated with cardiac arrest. In this study, we determined the cardiotoxicity of Mitragynine and other chemical constituents isolated using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs).

    METHODS AND RESULTS: The rapid delayed rectifier potassium current (IKr), L-type Ca2+ current (ICa,L) and action potential duration (APD) were measured by whole cell patch-clamp. The expression of KCNH2 and cytotoxicity was determined by real-time PCR and Caspase activity measurements. After significant IKr suppression by Mitragynine (10 µM) was confirmed in hERG-HEK cells, we systematically examined the effects of Mitragynine and other chemical constituents in hiPSC-CMs. Mitragynine, Paynantheine, Speciogynine and Speciociliatine, dosage-dependently (0.1∼100 µM) suppressed IKr in hiPSC-CMs by 67%∼84% with IC50 ranged from 0.91 to 2.47 µM. Moreover, Mitragynine (10 µM) significantly prolonged APD at 50 and 90% repolarization (APD50 and APD90) (439.0±11.6 vs. 585.2±45.5 ms and 536.0±22.6 vs. 705.9±46.1 ms, respectively) and induced arrhythmia, without altering the L-type Ca2+ current. Neither the expression, and intracellular distribution of KCNH2/Kv11.1, nor the Caspase 3 activity were significantly affected by Mitragynine.

    CONCLUSIONS: Our study indicates that Mitragynine and its analogues may potentiate Torsade de Pointes through inhibition of IKr in human cardiomyocytes.

    Matched MeSH terms: Delayed Rectifier Potassium Channels/metabolism
  16. Fulltext Impact of parameter variation in fabrication of nanostructure by atomic force microscopy nanolithography
    Dehzangi A, Larki F, Hutagalung SD, Goodarz Naseri M, Majlis BY, Navasery M, et al.
    PLoS One, 2013;8(6):e65409.
    PMID: 23776479 DOI: 10.1371/journal.pone.0065409
    In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (10(15) cm(-3)) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity.
    Matched MeSH terms: Potassium Compounds/chemistry
  17. Fulltext The antibacterial efficacy of silver diamine fluoride (SDF) is not modulated by potassium iodide (KI) supplements: A study on in-situ plaque biofilms using viability real-time PCR with propidium monoazide
    Abdullah N, Al Marzooq F, Mohamad S, Abd Rahman N, Rani KGA, Chi Ngo H, et al.
    PLoS One, 2020;15(11):e0241519.
    PMID: 33141868 DOI: 10.1371/journal.pone.0241519
    Silver diamine fluoride (SDF) is commonly used to arrest caries lesions, especially in early childhood caries. Recently, it was suggested that SDF can be combined with potassium iodide (KI) to minimize the discoloration of demineralized dentine associated with SDF application. However, the antibacterial efficacy of SDF alone or combined with KI on in-situ biofilm is unknown. Hence, we compared the anti-plaque biofilm efficacy of two different commercially available SDF solutions, with or without KI, using an in-situ biofilm, analysed using viability real-time PCR with propidium monoazide (PMA). Appliance-borne in-situ biofilm samples (n = 90) were grown for a period of 6 h in five healthy subjects who repeated the experiment on three separate occasions, using a validated, novel, intraoral device. The relative anti-biofilm efficacy of two SDF formulations; 38.0% Topamine (SDFT) and 31.3%, Riva Star (SDFR), KI alone, and KI in combination with SDFR (SDFR+KI) was compared. The experiments were performed by applying an optimized volume of the agents onto the biofilm for 1min, mimicking the standard clinical procedure. Afterwards the viability of the residual biofilm bacteria was quantified using viability real-time PCR with PMA, then the percentage of viable from total bacteria was calculated. Both SDF formulations (SDFT and SDFR) exhibited potent antibacterial activities against the in-situ biofilm; however, there was non-significant difference in their efficacy. KI alone did not demonstrate any antibacterial effect, and there was non-significant difference in the antibacterial efficacy of SDF alone compared to SDF with KI, (SDFT v SDFR/KI). Thus, we conclude that the antibacterial efficacy of SDF against plaque biofilms is not modulated by KI supplements. Viability real-time PCR with PMA was successfully used to analyze the viability of naturally grown oral biofilm; thus, the same method can be used to test the antimicrobial effect of other agents on oral biofilms in future research.
    Matched MeSH terms: Potassium Iodide
  18. Fulltext Seed biopriming with P- and K-solubilizing Enterobacter hormaechei sp. improves the early vegetative growth and the P and K uptake of okra (Abelmoschus esculentus) seedling
    Roslan MAM, Zulkifli NN, Sobri ZM, Zuan ATK, Cheak SC, Abdul Rahman NA
    PLoS One, 2020;15(7):e0232860.
    PMID: 32645001 DOI: 10.1371/journal.pone.0232860
    Limited information is available that seed biopriming with plant growth-promoting Enterobacter spp. play a prominent role to enhance vegetative growth of plants. Contrary to Enterobacter cloacae, Enterobacter hormaechei is a less-studied counterpart despite its vast potential in plant growth-promotion mainly through the inorganic phosphorus (P) and potassium (K) solubilization abilities. To this end, 18 locally isolated bacterial pure cultures were screened and three strains showed high P- and K-solubilizing capabilities. Light microscopy, biochemical tests and 16S rRNA gene sequencing revealed that strains 15a1 and 40a were closely related to Enterobacter hormaechei while strain 38 was closely related to Enterobacter cloacae (Accession number: MN294583; MN294585; MN294584). All Enterobacter spp. shared common plant growth-promoting traits, namely nitrogen (N2) fixation, indole-3-acetic acid production and siderophore production. The strains 38 and 40a were able to produce gibberellic acid, while only strain 38 was able to secrete exopolysaccharide on agar. Under in vitro germination assay of okra (Abelmoschus esculentus) seeds, Enterobacter spp. significantly improved overall germination parameters and vigor index (19.6%) of seedlings. The efficacy of root colonization of Enterobacter spp. on the pre-treated seedling root tips was confirmed using Scanning Electron Microscopy (SEM). The pot experiment of bioprimed seeds of okra seedling showed significant improvement of the plant growth (> 28%) which corresponded to the increase of P and K uptakes (> 89%) as compared to the uninoculated control plants. The leaf surface area and the SPAD chlorophyll index of bioprimed plants were increased by up to 29% and 9% respectively. This report revealed that the under-explored species of P- and K-solubilizing Enterobacter hormaechei sp. with multiple plant beneficial traits presents a great potential sustainable approach for enhancement of soil fertility and P and K uptakes of plants.
    Matched MeSH terms: Potassium
  19. Fulltext Removal of hydrogen sulfide from a biogas mimic by using impregnated activated carbon adsorbent
    Zulkefli NN, Masdar MS, Wan Isahak WNR, Md Jahim J, Md Rejab SA, Chien Lye C
    PLoS One, 2019;14(2):e0211713.
    PMID: 30753209 DOI: 10.1371/journal.pone.0211713
    Adsorption technology has led to the development of promising techniques to purify biogas, i.e., biomethane or biohydrogen. Such techniques mainly depend on the adsorbent ability and operating parameters. This research focused on adsorption technology for upgrading biogas technique by developing a novel adsorbent. The commercial coconut shell activated carbon (CAC) and two types of gases (H2S/N2 and H2S/N2/CO2) were used. CAC was modified by copper sulfate (CuSO4), zinc acetate (ZnAc2), potassium hydroxide (KOH), potassium iodide (KI), and sodium carbonate (Na2CO3) on their surface to increase the selectivity of H2S removal. Commercial H2S adsorbents were soaked in 7 wt.% of impregnated solution for 30 min before drying at 120°C for 24 h. The synthesized adsorbent's physical and chemical properties, including surface morphology, porosity, and structures, were characterized by SEM-EDX, FTIR, XRD, TGA, and BET analyses. For real applications, the modified adsorbents were used in a real-time 0.85 L single-column adsorber unit. The operating parameters for the H2S adsorption in the adsorber unit varied in L/D ratio (0.5-2.5) and feed flow rate (1.5-5.5 L/min) where, also equivalent with a gas hourly space velocity, GHSV (212.4-780.0 hour-1) used. The performances of H2S adsorption were then compared with those of the best adsorbent that can be used for further investigation. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties (i.e., crystallinity and surface area). BET analysis further shows that the modified adsorbents surface area decreased by up to 96%. Hence, ZnAc2-CAC clarify as the best adsorption capacity ranging within 1.3-1.7 mg H2S/g, whereby the studied extended to adsorption-desorption cycle.
    Matched MeSH terms: Potassium Iodide; Potassium Compounds
  20. Fulltext Estimating nutrient uptake requirements for soybean using QUEFTS model in China
    Yang F, Xu X, Wang W, Ma J, Wei D, He P, et al.
    PLoS One, 2017;12(5):e0177509.
    PMID: 28498839 DOI: 10.1371/journal.pone.0177509
    Estimating balanced nutrient requirements for soybean (Glycine max [L.] Merr) in China is essential for identifying optimal fertilizer application regimes to increase soybean yield and nutrient use efficiency. We collected datasets from field experiments in major soybean planting regions of China between 2001 and 2015 to assess the relationship between soybean seed yield and nutrient uptake, and to estimate nitrogen (N), phosphorus (P), and potassium (K) requirements for a target yield of soybean using the quantitative evaluation of the fertility of tropical soils (QUEFTS) model. The QUEFTS model predicted a linear-parabolic-plateau curve for the balanced nutrient uptake with a target yield increased from 3.0 to 6.0 t ha-1 and the linear part was continuing until the yield reached about 60-70% of the potential yield. To produce 1000 kg seed of soybean in China, 55.4 kg N, 7.9 kg P, and 20.1 kg K (N:P:K = 7:1:2.5) were required in the above-ground parts, and the corresponding internal efficiencies (IE, kg seed yield per kg nutrient uptake) were 18.1, 126.6, and 49.8 kg seed per kg N, P, and K, respectively. The QUEFTS model also simulated that a balanced N, P, and K removal by seed which were 48.3, 5.9, and 12.2 kg per 1000 kg seed, respectively, accounting for 87.1%, 74.1%, and 60.8% of the total above-ground parts, respectively. These results were conducive to make fertilizer recommendations that improve the seed yield of soybean and avoid excessive or deficient nutrient supplies. Field validation indicated that the QUEFTS model could be used to estimate nutrient requirements which help develop fertilizer recommendations for soybean.
    Matched MeSH terms: Potassium/metabolism
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