STR-957: EFFECTS OF CLT-INFILL WALLS ON THE COLLAPSE BEHAVIOR OF STEEL MOMENT RESISTING FRAMES

Over the past six years, to increase the use of renewable materials in the construction industry, a novel steel-timber hybrid building system was developed and studied at the University of British Columbia and FPInnovations. The hybrid structural system was a steel moment resisting frames (SMRFs) with Cross Laminated Timber (CLT) infill walls. These studies were mainly on developing: novel connection types, new constitutive laws for the CLT walls, and force-based and displacement-based design guidelines. The effect of CLT infills on the collapse risk of the SMRFs was not explicitly investigated, and is the topic of this paper. With consideration of seismicity of Vancouver (Canada)and using the 2010 National Building Code of Canada (NBCC) force based design guideline, 3- and 6-storey, 3-bay, bare and middle bay CLT-infilled SMRFs, were designed. Nonlinear analytical building models that account for the frame-infill interactions, were developed in the OpenSees finite element tool. L-shaped steel bracket connections were modeled using experimentally calibrated nonlinear two-node-link elements. Moreover, to allow brackets deformation, a small gap was provided at the interface of the steel frame members and CLT infill panels. To assess the collapse behavior and collapse fragility curves, incremental dynamic analysis was performed using 60 ground motion records selected with seismicity of Vancouver. The infill panels have significantly increased the collapse margin ratio, thereby reducing the collapse risk of SMRFs during server earthquake events

Tropical Splenomegaly Syndrome in a pregnant woman: A good response and prognosis to splenectomy

The tropical splenomegaly syndrome (TSS) is characterized by massive splenomegaly with hypersplenism, moderate hepatomegaly, and lymphocytic infiltration of the hepatic sinusoids. TSS is restricted to native residents of and visitors to the “malaria belt,” which roughly encompasses equatorial regions of South America, Africa, the Middle East, South Asia, and Southeast Asia. A 24 years old female patient gravida II and para I with gestational age 24 weeks from south west of Eritrea (Shelallo) Gash Barka presented with dizziness, general body weakness, and abdominal discomfort for 3 weeks and left upper quadrant swelling of three years duration. Other associate symptoms were palpitation and dyspnea. She had history of repeated malaria attack. Physical examination revealed massive hepatosplenomegaly and pallor. Hematological studies revealed that severe anemia Hgb 3.8 g/dL, WBC 2.2× 103/mm3, MCV 97.6fl. Platelet 30×103/mm3, and reticulocyte count was 7%. Peripheral smear examination revealed normocytic normochromic red blood cells. Bone marrow examination revealed marked erythroid hyperplasia without sign of malignancy and left shift. The patient received 11 units of blood preoperative but, no improvement Hb remaining 3.7g/dl. Elective splenectomy was done. Intra-operatively and postoperatively she received an additional 5 units of blood. There was no postoperative complication. The patient was discharged with Hb of 6.0g/dl with slight improvement. The response to splenectomy was good. Four months postoperative and 40 days post delivery Hbg 16.3g/dl and platelet 254,000/mm and WBC 5000/ mm3. The outcome and prognosis of splenectomy in this patient was satisfactory

Small-scale chemistry for a hands-on approach to chemistry practical work in secondary schools: Experiences from Ethiopia

The purpose of this study was to investigate the possibility of using a small-scale chemistry (SSC) approach as a means of performing chemistry practical activities in Ethiopian secondary schools. A total of eight  experiments from two topics, electrolysis and rate of reaction, in the  Ethiopian grade 11 chemistry syllabus were modified into SSC for use with the MyLab Chemistry Kits (Northwest University, South Africa). The  evaluation involved classroom testing of the SSC materials to investigate the effect of the approach compared to the regular teaching approach. Two comparable groups of Grade 11 science stream students (188 experimental; 195 control) and their chemistry teachers participated in the study. Triangulation procedures involving classroom observation of the use of the SSC approach in classrooms, student achievement tests (pre and post-test), questionnaires, and interviews were employed for data  collection. Results showed that the SSC approach can increase students understanding of chemistry concepts. Furthermore, despite the presence of some challenges in operating the smallscale equipment, collecting  quantitative data, and maintaining class discipline, the SSC approach was viewed by both teachers and students as cost and time saving, safer, easy to use and enjoyable. [AJCE 4(3), Special Issue, May 2014

Carbon sequestration and selected hydraulic characteristics under conservation agriculture and traditional tillage practices in Malawi

Conservation agriculture (CA) is increasingly promoted among smallholder farmers of sub-Saharan Africa in a quest to improve food security while sustaining the natural resource base of the agro-ecosystems where agriculture is based. The aim of this study was to investigate the effects of CA and traditional tillage on soil organic carbon (SOC) and selected hydraulic properties in two contrasting agro-ecological zones of Malawi. Six farmers hosted on-farm trials in each location, with each farmer having the following treatments: CA with continuous sole maize (CA-SM), CA with maize–legume intercrops (CA-ML), and traditional tillage with continuous sole maize (CT-SM). Soil samples were randomly collected in October 2015, from farmers’ fields located in Chipeni, Chinguluwe, Lemu, and Zidyana where CA had been implemented for 10 years (2005–2015) at six depth intervals: 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm. Bulk density, soil water characteristics, and pore size distribution were determined using undisturbed core samples. At all sites, CA improved total SOC, carbon stocks, and the stable fraction of particulate organic carbon. Maize–legume intercropping under CA had 35%, 33%, and 73% more total SOC than CT-SM in Chipeni, Lemu, and Zidyana respectively. In Chinguluwe and Lemu, CA-ML had 0.54 and 0.50 g kg–1 respectively more stable fraction of particulate organic carbon (POMP) than CT-SM; whereas in Chipeni, CA-SM had 0.73 g kg–1 higher POMP compared with CT-SM. CA also improved soil porosity, pore size distribution, and water retention capacity by increasing the proportion of mesopores and micropores compared with CT-SM. Thus, changing management practices from CT-SM to CA has the potential to improve the soil organic matter and soil hydraulic properties across agro-ecological zones in Malawi, which is important for sustainable agriculture. Farmers should be encouraged to minimise tillage, retain residues as mulch on the soil surface, and practice crop rotation

Vertical Distribution of Pasteuria penetrans Parasitizing Meloidogyne incognita on Pittosporum tobira in Florida

Pasteuria penetrans is considered as the primary agent responsible for soil suppressiveness to root-knot nematodes widely distributed in many agricultural fields. A preliminary survey on a Pittosporum tobira field where the grower had experienced a continuous decline in productivity caused by Meloidogyne incognita showed that the nematode was infected with Pasteuria penetrans. For effective control of the nematode, the bacterium and the host must coexist in the same root zone. The vertical distribution of Pasteuria penetrans and its relationship with the nematode host in the soil was investigated to identify (i) the vertical distribution of P. penetrans endospores in an irrigated P. tobira field and (ii) the relationship among P. penetrans endospore density, M. incognita J2 population density, and host plant root distribution over time. Soil bioassays revealed that endospore density was greater in the upper 18 cm of the top soil compared with the underlying depths. A correlation analysis showed that the endospore density was positively related to the J2 population density and host plant root distribution. Thus, the vertical distribution of P. penetrans was largely dependent on its nematode host which in turn was determined by the distribution of the host plant roots. The Pasteuria was predominant mostly in the upper layers of the soil where their nematode host and the plant host roots are abundant, a factor which may be a critical consideration when using P. penetrans as a nematode biological control agent

CSRD Technical Exchange: ICPAC and National Climate Maprooms – Existing and New Tools for Drought Monitoring and Forecasting in Eastern Africa

In 2005, the International Research Institute for Climate and Society published its assessment of key gaps in the use of climate information for health, agriculture, water and other sectors in countries across Africa. The results from the report were less than stellar. After an extensive review of use of climate information in the development sectors of Africa, the authors concluded that the continent suffered from “market atrophy” – the reinforcing effect of inadequate effective supply of climate information and weak effective demand. Twelve years later, organizations such as the IRI, CSRD program, CCAFS, ICPAC, and UKMO have made enormous strides at increasing both climate information supply and effective demand through the implementation of climate data platforms and the organizing of capacity-building seminars. In order to capitalize on the presence of the many climate and sector experts from across the IGAD region, the organizations above held a joint event, the CSRD Technical Exchange: ICPAC and National Climate Maprooms – Existing and New Tools for Drought Monitoring and Forecasting in Eastern Africa, in Zanzibar on August 23-25, 2017, immediately after the 47th Greater Horn of Africa Climate Outlook Forum (GHACOF47). The workshop was designed to offer potential and existing users a platform to voice their needs for the development and better use of historical, monitored and forecast information for the management of drought across climate-sensitive sectors

Soil methane (CH4) fluxes in cropland with permanent pasture and riparian buffer strips with different vegetation

Background Methane (CH4) has a global warming potential (GWP) 28 times that of carbon dioxide (CO2) over a 100-year horizon. Riparian buffers strips are widely implemented for their water quality protection functions along agricultural land, but conditions prevailing within them may increase the production of radiative greenhouse gases (GHGs), including CH4. However, a few information is available regarding the dynamics of unintended emissions of soil CH4 in these commonplace features of agroecosystems and how the dynamics compare with those for agricultural land. Aims To understand the dynamics of soil CH4 fluxes from a permanent upslope pasture and contiguous riparian buffer strips with different (grass, willow, and woodland) vegetation as well controls with no buffer vegetation, an experiment was carried out using the static chamber technique on a replicated plot-scale facility. Methods Gas fluxes were measured periodically with soil and environmental variables between June 2018 and February 2019 at North Wyke, UK. Results Soils under all treatments were sinks of soil CH4 with the willow riparian buffer (–2555 ± 318.7 g CH4 ha–1) having the lowest soil CH4 flux followed by the grass riparian buffer (–2532 ± 318.7 g CH4 ha–1), woodland riparian buffer (–2318.0 ± 246.4 g CH4 ha–1), no-buffer control (–1938.0 ± 374.4 g CH4 ha–1), and last, the upslope pasture (–1328.0 ± 89.0 g CH4 ha–1), which had a higher flux. Conclusions The three vegetated riparian buffers were more substantial soil CH4 sinks, suggesting that they may help reduce soil CH4 fluxes into the atmosphere in similar agroecosystems

Soil N2O and CH4 emissions from fodder maize production with and without riparian bufer strips of difering vegetation

Purpose Nitrous oxide (N2O) and methane (CH4) are some of the most important greenhouse gases in the atmosphere of the 21st century. Vegetated riparian bufers are primarily implemented for their water quality functions in agroecosystems. Their location in agricultural landscapes allows them to intercept and process pollutants from adjacent agricultural land. They recycle organic matter, which increases soil carbon (C), intercept nitrogen (N)-rich runof from adjacent croplands, and are seasonally anoxic. Thus processes producing environmentally harmful gases including N2O and CH4 are promoted. Against this context, the study quantifed atmospheric losses between a cropland and vegetated riparian bufers that serve it.Methods Environmental variables and simultaneous N2O and CH4 emissions were measured for a 6-month period in a replicated plot-scale facility comprising maize (Zea mays L.). A static chamber was used to measure gas emissions. The cropping was served by three vegetated riparian bufers, namely: (i) grass riparian bufer; (ii) willow riparian bufer and; (iii) woodland riparian bufer, which were compared with a no-bufer control. Results The no-bufer control generated the largestcumulative N2O emissions of 18.9 kg ha−1(95% confdence interval: 0.5–63.6) whilst the maize crop upslope generated the largest cumulative CH4 emissions (5.1±0.88 kg ha−1). Soil N2O and CH4-based global warming potential (GWP) were lower in the willow (1223.5±362.0 and 134.7±74.0 kg CO2-eq. ha−1 year−1, respectively) and woodland (1771.3±800.5 and 3.4±35.9 kg CO2-eq. ha−1 year−1, respectively) riparian bufers. Conclusions Our results suggest that in maize production and where no riparian bufer vegetation is introduced for water quality purposes (no bufer control), atmospheric CH4 and N2O concerns may resul

Soil CO2 emissions in cropland with fodder maize (Zea mays L.) with and without riparian buffer strips of differing vegetation

Vegetated land areas play a significant role in determining the fate of carbon (C) in the global C cycle. Riparian buffer vegetation is primarily implemented for water quality purposes as they attenuate pollutants from immediately adjacent croplands before reaching freshwater systems. However, their prevailing conditions may sometimes promote the production and subsequent emissions of soil carbon dioxide (CO2). Despite this, the understanding of soil CO2 emissions from riparian buffer vegetation and a direct comparison with adjacent croplands they serve remain elusive. In order to quantify the extent of CO2 emissions in such an agro system, we measured CO2 emissions simultaneously with soil and environmental variables for six months in a replicated plot-scale facility comprising of maize cropping served by three vegetated riparian buffers, namely: (i) a novel grass riparian buffer; (ii) a willow riparian buffer, and; (iii) a woodland riparian buffer. These buffered treatments were compared with a no-buffer control. The woodland (322.9 ± 3.1 kg ha− 1) and grass (285 ± 2.7 kg ha− 1) riparian buffer treatments (not significant to each other) generated significantly (p = < 0.0001) the largest CO2 compared to the remainder of the treatments. Our results suggest that during maize production in general, the woodland and grass riparian buffers serving a maize crop pose a CO2 threat. The results of the current study point to the need to consider the benefits for gaseous emissions of mitigation measures conventionally implemented for improving the sustainability of water resources

Do NO, N2O, N2 and N2 fluxes differ in soils sourced from cropland and varying riparian buffer vegetation? An incubation study

Riparian buffers are expedient interventions for water quality functions in agricultural landscapes. However, the choice of vegetation and management affects soil microbial communities, which in turn affect nutrient cycling and the production and emission of gases such as nitric oxide (NO), nitrous oxide (N2O), nitrogen gas (N2) and carbon dioxide (CO2). To investigate the potential fluxes of the above-mentioned gases, soil samples were collected from a cropland and downslope grass, willow and woodland riparian buffers from a replicated plot scale experimental facility. The soils were re-packed into cores and to investigate their potential to produce the aforementioned gases via potential denitrification, a potassium nitrate (KNO3−) and glucose (labile carbon)-containing amendment, was added prior to incubation in a specialized laboratory DENItrification System (DENIS). The resulting NO, N2O, N2 and CO2 emissions were measured simultaneously, with the most NO (2.9 ± 0.31 mg NO m−2) and N2O (1413.4 ± 448.3 mg N2O m−2) generated by the grass riparian buffer and the most N2 (698.1 ± 270.3 mg N2 m−2) and CO2 (27,558.3 ± 128.9 mg CO2 m−2) produced by the willow riparian buffer. Thus, the results show that grass riparian buffer soils have a greater NO3− removal capacity, evidenced by their large potential denitrification rates, while the willow riparian buffers may be an effective riparian buffer as its soils potentially promote complete denitrification to N2, especially in areas with similar conditions to the current study