Structural Characteristics of Unbound Aggregate Bases to Meet AASHTO 2002 Design Requirements: Interim Report

This report gives the results of a study of the properties of unbound aggregate base materials using both laboratory testing data from full scale field tests in Illinois, Georgia, and Texas, and a model of cross-anisotropic elastic materials to characterize the behavior of the base materials under traffic loads. Using the cross-anisotropic model, the stress distribution in a base course is more realistic than that developed when the aggregate base is considered to be linear and isotropic. The stress distribution based on cross-anisotropic analysis is not only more correct, but it is also more favorable to the unbound aggregate in that significant tensile stresses are found not to occur. The analogy is presented in this report that the response of the aggregate base to the load is as if the stress distribution directly under the wheel load due to anisotropy acts as a moving column under the wheel in which the aggregate essentially produces its own confinement and does not enter into tension. Other findings in this report include the following: 1) The unbound aggregate base material should be modeled as non-linear and cross-anisotropic to account for stress-sensitivity and the significant differences between vertical and horizontal moduli and Poisson’s ratios. 2) The ICAR laboratory testing protocol is efficient and precise and should be considered as a candidate to model the unbound aggregate base. The protocol uses three stress regimes and ten stress levels within each regime to determine stress sensitivity and cross-anisotropy. A system identification method is used to select the five material properties based on the tests results necessary to properly characterize the aggregate base and to satisfy the requirements of elastic work potential theory. 3) The Fast Industrial Process Controls cell is efficient and should be used to characterize unbound aggregate bases. The ratio of the diameter to the specimen height is 1:1. While testing of such sample sizes is discouraged in the literature, improvements made to the IPC cell minimize frictional development between the sample and loading platens resulting in minimal constraint at the sample ends. This is verified in the report based on comparative triaxial testing and finite element analysis. 4) The ICAR testing protocol is an excellent tool for both unbound aggregate characterization and comparative analysis of materials. A compaction study on two very different aggregates (uncrushed river gravel and crushed limestone) was performed in which the aggregates were subjected to impact, kneading gyratory compaction. The difference in the tendency of the compaction techniques to produce varying levels of particle orientation (which affects anisotropy) was evident in the degree of anisotropy measured.Aggregates Foundation for Technology, Research, and Education (AFTRE)Civil, Architectural, and Environmental Engineerin

Investigating major subject research areas of Council for Scientific and Industrial Research Journals in Ghana

Journals are important source of relevant and quality information. They provide current source of up-to-date information to facilitate research, teaching, learning and knowledge dissemination. The objective of the study is to investigate the major subject research areas covered by the articles of the five journals in the Council for Scientific and Industrial Research. The study was undertaken in the CSIR of Ghana in which a major device for data collection was quantitative content analysis. This mode of data collection was determined after its validity and reliability among 1,430 journal articles from four CSIR Institutes was proven. Data collected were analysed using tables and graphs to group major publications. Results from the research indicated that cereal and legumes recorded the highest (318) disciplines in all the five journals in the CSIR

A Study of the Publication pattern in CSIR- Plant Genetic Resources Research Institute

Plant genetic resources (PGR) are those resources that are of benefit to man. They are plant materials containing useful characters of actual or potential values. They are the basic raw mate­rials for crop improvement today and for the future. This paper analysed changes in publication trend by scientists from 1981 to 2015 at the CSIR-Plant Genetic Resources Research Institute. It investigated major commodities covered by the articles produced by scientists of the Institute. The main area of study included publication formats covered by the articles in the Plant Ge­netic Resources Research Institute Reference (PGRRIREF Directory) (1981-2015). The study also highlighted recent research and development activities in each publication discipline in the PGRRIREF Directory. It is believed that information gathered from the analysis of this research, would increase the utilization of the crop plants in Ghana and beyond. Content analysis method and interviews were used for the study of the Publication pattern in CSIR-Plant Genetic Re­sources Research Institute. The findings indicated among others that, socio-economic (27.2%), horticulture (21.5%), root and tubers (18.5%) recorded increasing publication disciplines. Tech­nologies developed in these publication disciplines could be put on-line for a wider audience to enhance efficient conservation and utilization of plant genetic resources materials. Keywords: CSIR-Plant Genetic Resources Research Institute; publication pattern; discipline; formats; research activitie

Safety of overlapping inpatient orthopaedic surgery: A multicenter study

BackgroundAlthough overlapping surgery is used to maximize efficiency, more empirical data are needed to guide patient safety. We conducted a retrospective cohort study to evaluate the safety of overlapping inpatient orthopaedic surgery, as judged by the occurrence of perioperative complications.MethodsAll inpatient orthopaedic surgical procedures performed at 5 academic institutions from January 1, 2015, to December 31, 2015, were included. Overlapping surgery was defined as 2 skin incisions open simultaneously for 1 surgeon. In comparing patients who underwent overlapping surgery with those who underwent non-overlapping surgery, the primary outcome was the occurrence of a perioperative complication within 30 days of the surgical procedure, and secondary outcomes included all-cause 30-day readmission, length of stay, and mortality. To determine if there was an association between overlapping surgery and a perioperative complication, we tested for non-inferiority of overlapping surgery, assuming a null hypothesis of an increased risk of 50%. We used an inverse probability of treatment weighted regression model adjusted for institution, procedure type, demographic characteristics (age, sex, race, comorbidities), admission type, admission severity of illness, and clustering by surgeon.ResultsAmong 14,135 cases, the frequency of overlapping surgery was 40%. The frequencies of perioperative complications were 1% in the overlapping surgery group and 2% in the non-overlapping surgery group. The overlapping surgery group was non-inferior to the non-overlapping surgery group (odds ratio [OR], 0.61 [90% confidence interval (CI), 0.45 to 0.83]; p < 0.001), with reduced odds of perioperative complications (OR, 0.61 [95% CI, 0.43 to 0.88]; p = 0.009). For secondary outcomes, there was a significantly lower chance of all-cause 30-day readmission in the overlapping surgery group (OR, 0.67 [95% CI, 0.52 to 0.87]; p = 0.003) and shorter length of stay (e, 0.94 [95% CI, 0.89 to 0.99]; p = 0.012). There was no difference in mortality.ConclusionsOur results suggest that overlapping inpatient orthopaedic surgery does not introduce additional perioperative risk for the complications that we evaluated. The suitability of this practice should be determined by individual surgeons on a case-by-case basis with appropriate informed consent.Level of evidenceTherapeutic Level III. See Instructions for Authors for a complete description of levels of evidence

Heavy Metal Loading in Surface Sediments along the Kawere Stream, Tarkwa, Ghana

Sediment contamination by heavy metals resulting from anthropogenic activities is increasingly becoming a global concern due to the risk it poses to human well-being and ecological integrity at large. The purpose of this study was to assess the heavy metals loading in sediment along the Kawere stream. Ten sediment samples were collected, acid digested and analysed for copper (Cu), lead (Pb), cadmium (Cd), manganese (Mn), zinc (Zn), nickel (Ni), chromium (Cr), cobalt (Co) and iron (Fe) using a Varian AA240FS Atomic Absorption Spectrometer (AAS). The Australian and New Zealand Environment and Conservation Council (ANZECC) guidelines for freshwater sediment quality was used as the benchmark against which the measured metal concentrations were compared. Nemerow’s pollution and potential ecological risk indices were used to evaluate the pollution status and ecological risk levels of the heavy metals in the stream. The results obtained indicated that, except Cu which exceeded the ANZECC trigger value of 65 mg/kg at three sampling sites (K01=171.29 mg/kg, K05=170.83 mg/kg and K07=113.31 mg/kg), all other measured heavy metals concentrations were below their corresponding ANZECC values. Heavy metal pollution assessment showed that three samples (K01, K05 and K07) were slightly polluted, suggesting the likelihood of posing a health threat to the aquatic organisms and humans. Calculated Ecological Risk Index (RI) ranged from 3.229 to 19.750 (RI < 150), representing a low ecological risk. As such, the metals, Cu, Ni, Cd, Pb, Cr, and Zn pose a low ecological risk to the aquatic ecosystem. Although the ecological risk is low based on the current results, constant monitoring of the stream quality is recommended due to the increasing human activities along the stream as well as the sediments ability to accumulate and remobilise heavy metals back into the water column and possibly transferring them through the food chain.   Keywords: Heavy Metals, Sediment, Ecological Risk Assessment, Pollution, Strea

Germplasm collection and ethnobotany of taro (Colocasia esculenta L. Schott) from nineteen districts in the Ashanti, Eastern and Western regions of Ghana

Germplasm collection and ethnobotanical documentation are necessary for effective conservation and management of plant genetic resources. Taro (Colocasia esculenta L. Schott) is one of the staple root and tuber crops in Ghana. The study reports the germplasm and ethnobotanical information of taro collected from 19 districts in the Ashanti, Eastern and Western regions of Ghana. A germplasm collection expedition was undertaken in 58 towns in the districts. Fifty donors were interviewed on the ethnobotany of taro, using a questionnaire based on International Plant Genetic Resources Institute (IPGRI) descriptors for taro. Sixty taro accessions were collected from fields (34), home gardens (23), roadside stalls (2) and the wild (1). Respondents comprised of 27 males and 23 females. (62%). According to respondents of the survey, taro is used for food (100%), animal feed (44%) and folk medicine (4%). The corms (100%) and leaves (64%) are the parts of the plant used. The crop is grown mainly on a small scale for subsistent use by 70 percent of the respondents. Taro leaf blight (TLB) and lack of planting materials were the main constraints to large scale production. Respondents perceived the outbreak of TLB was due to the use of agrochemicals in farming practices in recent times (80%), irradiation (26%) and mythical reasons (10%). There is the need to educate taro growers on the causes and management of taro leaf blight

Simultaneous Quantification of Lamivudine, Zidovudine and Related Impurities in Fixed Oral Dosage Combination Using RP-HPLC with DAD detection

A simple and fast isocratic Reverse Phase High Performance Liquid Chromatography (RP-HPLC) method has been developed and validated for the simultaneous determination of Lamivudine, zidovudine and their related impurities in tablets. The method consists of a mobile phase combination of Acetonitrile (HPLC grade) and Buffer (0.0680 g of Potassium Dihydrogen Orthophosphate, 0.3 ml of Triethylamine, pH adjusted to 8.0 with Orthophosphoric acid to a final volume preparation of 100 ml) in the ratio 10:90. Phenomenex Luna 5-µm C18 (2)-250 x 4.6-mm, 5-µm) was used as the stationary phase. The column oven was set to a temperature of 30±1oC. Quantification was achieved with a DAD detector set at 270 nm. Resolution was achieved at a short run time of 25 minutes. Zidovudine related impurity C, Lamivudine, salicylic acid, Zidovudine and Zidovudine related impurity B eluted at 3.749±0.004, 4.862±0.013, 15.332±0.064, 21.201±0.076 and 23.682±0.117 respectively. Relative retention times (RRT) for lamivudine unknown related impurities with respect to Zidovudine were 0.15, 0.17, 0.30 and 0.59. RRT for Zidovudine unknown related impurities with respect to Zidovudine were 0.39 and 0.63.  The method was found to be specific, robust, accurate and precise for the estimation of Zidovudine related impurity C, Lamivudine, salicylic acid, Zidovudine and Zidovudine related impurity B in fixed oral dosage tablets over the concentration ranges of 0.0204 mg/mL-0.0088 mg/mL, 0.0962 mg/mL-0.7699 mg/mL, 0.1929 mg/mL-1.5410 mg/mL and 0.0088 mg/mL-0.024 mg/mL respectively. The Correlation Coefficient (r2) for Zidovudine related impurity C, Lamivudine, salicylic acid, Zidovudine and Zidovudine related impurity B were greater than 0.998. The LOD were found to be between 1.9x10-4 mg/mL to 2.69 x10-4 mg/mL.  The proposed method is precise, specific, accurate and robust for the simultaneous estimation of Zidovudine related impurity C, Lamivudine, salicylic acid, Zidovudine, Zidovudine related impurity B and other related impurities in dosage forms. Keywords: Zidovudine related impurity C, Lamivudine, salicylic acid, Zidovudine, Zidovudine related impurity B, Lamivudine related impurities, Zidovudine related impurities RP-HPLC, Validation.