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1.
Abiola O. Ajayeoba Adewoye A. Olanipekun Wasiu A. Raheem Oluwaseun O. Ojo Ayowumi R. Soji–Adekunle 《声与振动》2021,55(1):69-85
Economic wood processing employs the use of industrial machines for cutting, shaping, milling, and sawing timber, thereby leading to the generation of high levels of noise. Published data from empirical studies have categorized noise as an environmental hazard of global significance. Furthermore, noise exposure limits for different industries and all the industrial machines available has not been formally established as it presently exists in developed nations around the world. Therefore, this study assessed the daily exposure of sawmills workers to noise in Southwestern Nigeria. Reconnaissance surveys were first carried out in Osun, Oyo, Ondo, Ekiti, Lagos, and Ogun States to select sawmills that were fully operational and fit for the study. Two fully functional sawmills in two cities of each State were eventually selected for data collection, making a total of 24 sawmills, while the Circular Machines (CM), Planer Machines (PM), and Band-saw Machines (BM) were the machines in each sawmill considered. Two machines each of CM, PM, and BM were considered in each sawmill, making a total of forty-eight (48) machines each of CM, PM, and BM. Sound data were collected between 7 am and 7 pm each day for six days (between Monday and Saturday) using Extech 407732 sound level meter and all stabilized measurements were taken three times at different intervals. The data collected were in three different periods: Machine No-work Period (NPm), Machine Idle Period (IPm), and Machine Working Period (WPm). A two–way Analysis of Variance (ANOVA) was carried out at P < 0.05 to determine whether there is a significant difference in the sound level average before and after the break, for both the idle and working periods of the three machines considered. This was also done to determine whether there is a significant difference between the sound level average of the results collected during idle and working periods of the three machines. Noise Pollution Levels (Lnp) ranged from 83.20 dB (PM) to 107.65 (BM) and 93.42 (CM and PM) – 116.00 (BM) respectively, while IPm also gave the least noise pollution level of 95.79 dB and WPm gave the highest level of 102.88 dB. The results revealed that all the machines’ Lnp values in the working period are more than the 90 dB acceptable limit the recommendation value of 90 dB while 89.6% of CMs, 75% of PMs, and 89.6% of BM had their Lnp above 90 dB in the idle period respectively. The minimum and the maximum noise dose levels for IPm, WPm and overall are 0.09 (BM) and 2.37 (CM), 0.50 (CM), and 4.77 (PM) and 0.69 (BM) and 6.64 (PM) respectively. The study found out that the fundamental contributing factors to the high noise levels in sawmills are poor machine maintenance, use of old and obsolete machines, poor housekeeping strategy, limited space, workers’ negligence, lack of PPE, and lack of occupational safety training. The study recommends that proper workplace practices such as use of personal protective equipment, new and modern machines, training, and occupational safety programmes be implemented in the considered sawmills. 相似文献
2.
M. A. Durosinmi J. O. Ojo A. F. Oluwole O. A. Akanle W. Arshed N. M. Spyrou 《Journal of Radioanalytical and Nuclear Chemistry》1993,168(1):233-242
Instrumental Neutron Activation Analysis (INAA) and Proton-Induced X-ray Emission (PIXE) analysis (employed as a complementary technique) have been used to determine the concentration of 11 elements in blood samples and its components erythrocytes and plasma obtained, from three groups of subjects in Nigeria viz: sickle cell anaemia (SCA) subjects, subjects with sickle cell trait and normal control subjects. The results suggest that SCA subjects have significantly higher concentrations of Na, Cl, Ca and Cu in their whole blood and erythrocytes and a higher concentration, of Cl and Cu in their plasma relative to the control subjects. Furthermore, a significantly lower concentration of K, Fe, Zn, Se, Br and Rb were found in the whole blood and erythrocytes of the SCA subjects as compared to the controls while the concentration of K and Fe in the plasma of the SCA subjects were however, found to be significantly higher than that of the control group. The study also shows that there was no significant differences between the concentration of these 11 elements in the group with sickle cell trait and the normal control group. 相似文献
3.
A study of the fragmentation of the \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{\left({{\rm C}_{\rm 6} {\rm H}_{\rm 6} {\rm O}} \right){\rm Fe}} \right]_{}^{_.^ + } $\end{document} ion formed from two different precursors suggests that the ions adopt different structures over that part of the energy distribution giving rise to decomposition in the ion source. 相似文献
4.
Jonathan F. Ojo Jide Ige Grace O. Ogunlusi Olanrewaju Owoyomi Esan S. Olaseni 《Transition Metal Chemistry》2006,31(3):337-339
The reactions between Fe(Phen)32+[phen = tris-(1,10) phenanthroline] and Co(CN)5X3− (X = Cl, Br or I) have been studied in aqueous acidic solutions at 25 °C and ionic strength in the range I = 0.001–0.02 mol dm−3 (NaCl/HCl). Plots of k2 versus √I, applying Debye–Huckel Theory, gave the values −1.79 ± 0.18, −1.65 ± 0.18 and 1.81 ± 0.10 as the product of charges (ZAZB) for the reactions of Fe(Phen)32+ with the chloro-, bromo- and iodo- complexes respectively. ZAZB of ≈ −2 suggests that the charge on these CoIII complexes cannot be −3 but is −1. This suggests the possibility of protonation of these CoIII complexes. Protonation was investigated over the range [H+] = 0.0001 −0.06 mol dm−3 and the protonation constants Ka obtained are 1.22 × 103, 7.31 × 103 and 9.90 × 102 dm6 mol−3 for X = Cl, Br and I, respectively. 相似文献
5.
Conductivity as a Sensor for Monitoring Relative Magnesium Corrosion Rates in Real‐time,in Serum‐containing Media under Cell Culture Conditions
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Kolade Ojo Tracy Hopkins Madhura Joshi Pravahan Salunke Guangqi Zhang Keaton Nahan Zhannping Zhang Daoli Zhao Sarah K. Pixley Vesselin Shanov William R. Heineman 《Electroanalysis》2016,28(12):3000-3008
Because controlling the corrosion rate of magnesium metal will be crucial to the success of biomedical implants containing pure magnesium or magnesium alloys, many ways have been sought to improve in vitro tests to analyze corrosion rates, and also to identify new methods of preparing or post‐processing magnesium. In this work, for an in vitro assay, we explored the use of a commercially available conductivity sensor to study magnesium corrosion under cell culture conditions that duplicate many physiologically appropriate parameters. With this sensor, we studied the corrosion of two previously untested magnesium single crystal samples that differed in surface treatments that could alter corrosion rates. The results show that the relative conductivity changes in (mS/cm) over the total time of immersion were proportional to the corrosion rates in (mm/y) and also to the total magnesium released, as detected by inductively coupled plasma mass spectrometry (ICP‐MS). 相似文献
6.
David G. Cameron Harry R. Hudson Isaac A. O. Ojo Max Pianka 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):183-197
Abstract N-(ω-Aminoalkyl)- and N-(ω-guanidinoalkyl)-aminoalkanephosphonic acids have been prepared from α, ω-diaminoalkanes by reaction with chloromethanephosphonic acid (or an ester of a halogeno-alkanephosphonic acid), followed by treatment with S-methylisothiouronium chloride. Ethylene diamine yielded 1-phosphonomethyl-2-iminoimidazolidine. A number of 1:1 salts of the α, ω-diamines and chloromethanephosphonic acid are also reported. Doubly charged zwitterionic structures are assigned to both ω-amino and ω-guanidino compounds on the basis of 31P and 13C nmr data. Thus the addition of an excess of acid (D2SO4) causes the 31P chemical shift to move to higher field, from ca. 8 to 14 ppm, whilst 1 Jpc increases from ca. 130 to 150 Hz. The 1H and 13C chemical shifts of the terminal methylene groups in the polymethylene chain are unaffected by acidification. Fast atom bombardment mass spectrometry gives rise to characteristic [M + H]+ ions, frequently as the base peak, and to fragmentations involving the loss of phosphorous acid, or the formation of ions resulting from carbon-nitrogen or carbon-carbon cleavage. The compounds show activity against a number of fungal pathogens and other microbial organisms. 相似文献
7.
Gugulethu Miya Mongikazi Nyalambisa Opeoluwa Oyedeji Mavuto Gondwe Adebola Oyedeji 《Molecules (Basel, Switzerland)》2021,26(11)
The medicinal potential and volatile composition of different parts of three cultivars of grapefruit (Citrus paradisi) were evaluated for their toxicity and anti-inflammatory activities. Fresh leaf and fruit peel were separately isolated by hydrodistillation for 4 h. The essential oils were subjected to GC/GC-MS analysis for chemical profile. Toxicity of the essential oils in mice were evaluated using Lorke’s method, while an anti-inflammatory assay was performed in a rat model using egg albumin-induced oedema. The oils obtained were light yellow in colour, and odour varied from strong citrus smell to mild. Percentage yield of fresh peel oil (0.34–0.57%) was greater than the fresh leaf oil yield (0.21–0.34%). D-limonene (86.70–89.90%) was the major compound identified in the leaf oil, while β-phellandrene (90.00–91.01%) dominated the peel oil. At a dosage level of 5000 mg/kg, none of the oils showed mortality in mice. An anti-inflammatory bioassay revealed that all the oils caused a significant (p < 0.05–0.01) reduction in oedema size when compared to the negative control group throughout the 5 h post induction assessment period. The study reveals that the oils are non-toxic and demonstrate significant anti-inflammatory activity. Our findings suggest that the leaf and peel oils obtained from waste parts of grapefruit plants can be useful as flavouring agents, as well as anti-inflammatory agents. 相似文献
8.
The hydrodistilled essential oils of the leaves of Senecio pterophorus collected from three different localities in KwaZulu-Natal Province, South Africa have been analyzed by GC and GC/MS. Thirteen - eighteen compounds were identified, accounting for over 98% of the total oil composition. The major components of the oils were limonene (10.3 - 32.3%), myrcene (14.4-19.7%), sabinene (13.0-18.0%), alpha-phellandrene (3.4-16.9%) and p-cymene (15.6-16.7%). 相似文献
9.
Thomas R. Cundari Smitha S. Janardan Olayinka Olatunji‐Ojo Brent R. Wilson 《International journal of quantum chemistry》2011,111(15):4303-4308
A computational study of diatomic NiAl is reported. Molecular properties evaluated include the equilibrium bond length (re), equilibrium stretching frequency (ωe), doublet‐quartet energy splitting, and nickel‐aluminum bond strength. Several interesting conclusions have resulted from this research. First, convergence in calculated properties is smoother with recently reported correlation consistent basis sets than earlier basis sets for Ni and Al. Second, with the exception of bond strength, basis set limit properties extrapolated using correlation basis sets are in agreement with reported data. Third, this research suggests that caution may be needed with regard to the use of DFT for developing interatomic potentials for larger scale simulations. For example, B97‐1 showed better agreement with reported re for 2NiAl than B3LYP. However, the situation was reversed for the calculation of ωe. With respect to bond strength, the situation is unclear due to the scatter among experiment and calculations. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
10.
Ojo Oluwasegun Taiwo Fernández Anta Antonio Lillo Rosa E. Sguera Carlo 《Advances in Data Analysis and Classification》2022,16(3):725-760
Advances in Data Analysis and Classification - We propose two new outlier detection methods, for identifying and classifying different types of outliers in (big) functional data sets. The proposed... 相似文献