Mozambique's infrastructure : a continental perspective

In the last 10 years, Mozambique's economy has grown steadily at an impressive rate of 7.7 percent per year, driven by the service sector, light industry, and agriculture. This pace is expected to continue or even increase with the massive influx of already-planned investment on the order of $15-20 billion. Mozambique's infrastructure is well developed in some sectors, including its east-west transport infrastructure, power grid, and water and sanitation networks. But the nation still faces critical challenges in these and other areas, including developing north-south transport connections, properly managing the water system, and expanding hydroelectric generation to meet potential. Mozambique spent about$664 million per year on infrastructure during the late 2000s, with as much as $204 million lost annually to inefficiencies. Comparing spending needs with existing spending and potential efficiency gains leaves an annual funding gap of$822 million per year. Mozambique could reduce inefficiency losses by positioning itself as a key power exporter. The country could reach infrastructure targets in 20 years through a combination of increased finance, improved efficiency, and cost-reducing innovations.Transport Economics Policy&Planning,Infrastructure Economics,Town Water Supply and Sanitation,Energy Production and Transportation,Water Supply and Systems

Mecanismos de interacción de concha de ostra, zeolita y lodo rojo (redmud) y su aplicabilidad para la movilización de metales pesados en diversos escenarios de contaminación

Descargue el texto completo en el repositorio institucional de la Seoul National University: https://hdl.handle.net/10371/178197En el presente trabajo, se evaluaron la concha de ostras marinas, residuo de la industria marina; zeolita, material con alta capacidad absorbente; y Red Mud, residuo de la producción de Alúmina como materiales aditivos en la remediación de suelos contaminados con metales pesados (Pb, Cd, Cu and Zn). Para evaluar el rendimiento de inmovilización de los metales pesados, se emplearon diversos métodos, siendo las muestras de suelos provenientes de tres zonas contaminadas en Corea del Sur y una muestra artificial de suelo contaminado altamente contaminado con plomo. Las pruebas experimentales se iniciaron con la batería de pruebas de absorción directa entre los aditivos y las muestras de suelo contaminado mediante pruebas de lixiviación. Después de aplicaron los materiales en la prueba de cultivo de suelo para evaluar los materiales a largo plazo simulando condiciones similares al medio ambiente. De los resultados concluimos que el rendimiento puede verse afectado por varios factores, como el pH del medio, el tiempo de contacto y la concentración inicial de metales pesados en estado inicial de la muestra. Por ejemplo, el uso de polvo de ostras alcanzó una eficiencia de inmovilización del 82% frente al plomo y de 78% frente al cobre en una evaluación directa con el suelo.In the present work, the shell of marine oysters, a residue of the marine industry, was evaluated; zeolite, material with high absorbent capacity; and Red Mud, residue from the production of Alumina as additive materials in the remediation of soils contaminated with heavy metals (Pb, Cd, Cu and Zn). To evaluate the immobilization performance of heavy metals, various methods were used, being soil samples from three contaminated areas in South Korea and an artificial sample of contaminated soil highly contaminated with lead. The experimental tests began with the battery of direct absorption tests between the additives and the soil samples contaminated by leaching tests. After the materials were applied in the soil cultivation test to evaluate the materials in the long term simulating conditions similar to the environment. From the results we conclude that the performance can be affected by several factors, such as the pH of the medium, the contact time and the initial concentration of heavy metals in the initial state of the sample. For example, the use of oyster dust achieved an 82% immobilization efficiency against lead and 78% against copper in a direct evaluation with soil.본 연구에서는 해양 산업의 잔재인 바다 굴의 껍질을 평가했습니다. 흡수력이 높은 물질인 제올라이트; 및 Red Mud, 중금속(Pb, Cd, Cu 및 Zn)으로 오염된 토양을 개선할 때 첨가제 재료로 사용되는 알루미나 생산의 잔류물. 중금속의 고정화 성능을 평가하기 위해 국내 오염지역 3곳의 토양시료와 납 오염도가 높은 오염토양의 인공시료를 사용하는 등 다양한 방법을 사용하였다. 실험 테스트는 첨가제와 침출 테스트로 오염된 토양 샘플 사이의 직접 흡수 테스트 배터리로 시작되었습니다. 토양재배시험에 재료를 적용한 후 환경과 유사한 장기 모의조건에서 재료를 평가하였다. 결과로부터 우리는 매체의 pH, 접촉 시간 및 샘플의 초기 상태에서 중금속의 초기 농도와 같은 여러 요인에 의해 성능이 영향을 받을 수 있다는 결론을 내렸습니다. 예를 들어, 굴 가루를 사용하면 토양에 대한 직접 평가에서 납에 대해 82%, 구리에 대해 78%의 고정 효율을 달성했습니다.Corea del Sur. KGSP-Korean Government Scholarship. Program 201

굴패각, 제올라이트 및 레드 머드 결합 메커니즘 기반 오염시나리오에 따른 독성 중금속 고정화 기술 적용가능성 평가

학위논문(석사) -- 서울대학교대학원 : 공과대학 건설환경공학부, 2021.8. Junboum Park.Oyster shell powder (OS), zeolite (Z), and red mud (RM) has elicited the attention of researchers as binders for the stabilization/ solidification technique used to remediate polluted soil. However, their immobilization performance with respect to potentially toxic metals can be affected by various factors, such as the pH of the medium, contact time, and initial heavy metal concentration. Therefore, this study seeks to investigate the performance of OS, Z and RM in stabilizing four type of contaminated soils. The batch experimental tests performed in the first binder evaluation consisted of mixed binder with the contaminated soil and measured the toxic metal concentration by using leaching tests. The second binder evaluation was set up to evaluate the best two binders from the previous evaluation facing arsenic pollution in As-contaminated soil by pot cultivation test and in As-solution by sorption batch test. As a result, from the batch experimental tests, OS bound approximately 82% of Pb and 78% of Cu in the soil samples of silty sand from abandoned metallic mine site (Case I) and soil samples from sandy soil from a military zone (Case II), respectively. On the other hand, Z was highly effective in stabilizing Pb in highly polluted soil (handmade contaminated soil HCS, Case III) binding more than 50% of Pb at lower dosages than those of OS and RM, RM showed an instable performance when it was applied to soil with low toxic metal concentrations (Case I and II), but achieved a remarkable Pb immobilization rate at dosages over 5% in highly contaminated soil (Case III). Furthermore, the Pb-immobilization capacity of OS improved considerably when the contact time increased, after 1 day it bounded 87% of Pb and after 10 days it was 94%. This basically occurs due to OS and RM are better at driving an acidic medium to an alkaline state. Results from the second binder evaluation indicates that Z was better binding arsenic in a soil environment (Case IV) compared to OS (up to 60%) and it can be attributed to high CEC which interact with the soil minerals, instead of the adsorption mechanism. In addition, in an aqueous solution, where the absorbent was directly in contact with As (III), using a binder-to-liquid ratio of 1:5, OS and Z only reduced around 10% of As (III) concentration. The fit Freundlich isotherms suggested that the adsorption behavior of arsenic was single-layered on the surface for both binders. Further experiments were conducted to observe the influence of adding OS, Z and RM in soil that later will be used as fill materials. In terms of geotechnical properties, the addition of OS increases the maximum dry unit weight, while Z and RM decrease this value, and also increase the optimum water content due to the capacity of Z and RM to hold water. Considering that samples were prepared at 95% compactness; direct shear test results showed a slight decrease in the friction angle (between 7 to 11%) and increase in its cohesion parameter. To recommend a suitable binder for each condition scenario, the initial concentration of the toxic metal, type of toxic metal, and pH medium are recognized as the main factors that can influence the binding process. Especially when the pH medium increases after binding addition hydroxyl ions participate directly in the precipitation of metals. Also, this study showed that the binder dosage increment can be favorable to the reduction of toxic metal concentration, but further evaluation should be done to avoid secondary pollution. For example, the risk associated with RM about releasing other metalloids (water-soluble Al concentrations in RM). Based on the results of the present study, the binders OS, Z, and RM can be used for immobilization of toxic metal through different binding mechanisms: OS by causing the precipitation of heavy metal and physical adsorption, Z by ion exchange capacity and physical adsorption, and RM by precipitation of toxic metal and ion exchange capacity. However, it is highly important to identify the limitations of its application according to each pollution scenario.굴패각 (Oyster shell - OS), 제올라이트(Zeolite - Z), 레드 머드 (Red mud - RM)는 오염된 토양을 제어하고, 복원하는 안정화 및 고형화기법을 기반으로 하는 안정화제로 연구자들의 관심을 끌고 있다. 이러한 과정은 중금속을 고정하는 매체의 pH, 접촉 시간, 초기 중금속 농도의 영향을 받을 수 있다. 본 연구에서는 중금속 오염토양에 대한 네 가지 시나리오의 상황에서 중금속을 안정시키는OS, Z, RM의 성능을 조사하고자 한다. 오염토양 및 안정화제의 광물학적 특성을 규명한 후, 안정화제의 중금속 용출 저감 효율을 비교하기 위해 첫 번째 평가에서는 혼합 배치 실험을 다양한 중금속 오염토양과 혼합된 안정화제로 구성하였고, 정규추출법을 적용하여 독성 중금속 농도를 측정하였다. 두 번째 안정화제 평가는 비소오염 실내포트 토양배양실험 및 비소 흡착배치 실험을 수행한 것으로 이전 평가에서 나타난 가장 효과적인 안정화제 두 가지를 사용하였다. 혼합배치 실험에서 토양 용출법을 통한 결과를 살펴보면OS는 광산 현장(Case I)의 토양 샘플과 군사 지역의 모래 토양 샘플(Case II)에서 각각 Pb의 약 82%와 Cu의 78%를 제어/결합하였다. 반면 Z는 오염이 심한 토양(인공오염토양 HCS, Case III)에서 Pb를 OS, RM보다 낮은 용량에서 50% 이상 결합시키는 데 매우 효과적이었으며, RM은 독성금속 농도가 낮은 토양(Case I, II)에 적용했을 때 불안정한 성능을 보였다. 하지만 5% 이상으로 RM을 사용할 때 Pb가 고형화/안정화된 것으로 나타났다. 또한 OS의 Pb-안정화 성능은 접촉 시간이 증가할 때 상당히 개선되었으며, 1일 후에는 Pb의 87%, 10일 후에는 94%로 발현되었다. 이는 기본적으로 OS와 RM이 Z에 비하여 산성 매체를 알칼리 상태로 쉽게 변화시킬 수 있기 때문으로 사료된다. 두 번째 안정화제 평가의 결과에서는, 비소토양(Case IV)에서 Z가 OS (최대 60 %)에 비해 비소 결합이 더 우수했으며 흡착 메커니즘 대신 토양 광물과 상호 작용하는 높은 양이온교환용량이 원인 일 수 있음을 나타낸다. 또한 흡착제가 As(III)와 직접 접촉한 수용액에서는 1: 5(결합제: 액체)을 사용하여 OS와 Z는 As (III) 농도의 10 % 만을 감소시켰다. Freundlich 등온선은 비소의 흡착 거동이 두 안정화제의 표면에 단일 층으로 형성된다 라는 것을 제시하였다. 안정화/고형화 법을 통해 안정화제로 사용될 토양에 OS, Z, RM 첨가의 영향을 관찰하기 위해 추가 실험을 진행하였다. 지질 공학적 측면에서 OS를 추가하면 최대 건조 단위 중량이 증가하는 반면 Z 및 RM은 이 값을 감소시키고 Z 및 RM의 최적함수비를 증가시킨다. 흡착 시험 안정화제가 함유된 95 % 다짐 샘플로 직접전단시험을 수행한 결과에 따르면 내부마찰각이 7 ~ 11 % 범위에서 약간 감소하는 경향을 보였으며 점착력은 증가하는 것으로 나타났다. 각 조건 시나리오에 적합한 결합제를 선정하기 위한 실험에서 독성 중금속의 초기 농도, 독성 중금속 유형 및 pH 매체가 결합 과정에 영향을 미칠 수 있는 주요 요인으로 나타났다. 특히 안정화제를 추가 후 pH 가 증가하면 수산기 이온이 금속 침전에 직접 참여한다. 또한 본 연구는 안정화제의 용량 증가가 독성 중금속 농도 감소에 유리할 수 있음을 보여주었지만 2차 오염을 피하기 위해 추가 평가를 수행해야한다. 예를 들면, 다른 여타의 중금속 (RM의 수용성 Al 농도) 용출에 대한 RM의 위험성에 대한 검토가 필요하다고 본다. 본 연구의 결과를 통하여 안정화제 OS, Z, RM은 서로 다른 메커니즘을 통하여 중금속의 안정화 및 고형화에 사용될 수 있음을 알 수 있었으며, 특히 굴패각 (OS)은 중금속 침전 및 물리적 흡착을, Z는 양이온교환 및 물리적 흡착이 우세한 것으로 나타났다. 독성 중금속의 침전 및 양이온교환에 의한 RM의 기작은 오염부지에서 중금속과 결합할 수 있을 것으로 연구된다. 그러나 각 오염 시나리오에 따라 적용 한계를 파악하는 것이 매우 중요하다.Chapter 1 : Introduction 1 Chapter 2 : Literature review 7 Chapter 3 : Materials and methods 17 Chapter 4 : Results 33 Chapter 5 : Discussions 48 Chapter 6 : Conclusions and further studies 54 Bibliography 57 Appendix 64 List of Tables A 64 List of Figures A 64 Abstract in Korean 72석

Las regletas de cuisenaire un recurso didáctico favorable en los procesos de inclusión

El propósito de este taller es acercar a los asistentes a una experiencia de trabajo con población en condición de diversidad, en este caso estudiantes de baja visión y ciegos. El recurso de las regletas de Cuisenaire permite concretar una ruta de enseñanza y de aprendizaje de la proporcionalidad. Con este taller se reflexionará sobre el recurso inclusivo que no requiere adaptaciones significativas, pero sí sobre la necesidad de hacer adaptaciones particulares en la planeación y gestión cuando se atiende población con alguna necesidad educativa específica. Las tareas de planear, gestionar y evaluar, son constitutivas de la práctica del profesor, por eso es necesario reflexionar sobre estrategias que le permitan en cada una de estas tareas, acoger la diversidad de manera eficaz, responsable y comprometida

Nectar sugar composition and flower visitors for the naturalized exotic Lantana camara (Verbenaceae) at Central Argentina

The aim of this work is to describe and quantify the flower visitors of the invasive Lantana camara L. (Verbenaceae) at the Chaco forest, and to analyze possible relations between nectar sugar composition and the main pollinators for this species. Volumes of nectar and sugar concentration were measured in six different populations of the naturalized exotic L. camara in Central Argentina. Quantitative nectar sugar composition was determined and compared between populations. In general, nectar sugar concentration ranged between 25-28% and volume per flower was very low (<1μL). Nectar sugars are glucose, fructose and sucrose for all populations, but hexoses clearly predominate over sucrose. Different insects were registered visiting the inflorescences. The more frequent pollinators were many species of diurnal butterflies, honeybees and bumblebees. A diverse insect assemblage visiting flowers of L. camara guarantees a high fruit production which can be related to the invasion process of this species in the Chaco region from Central Argentina.Fil: Torres, Carolina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Galetto, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

Hydrogenation of furfural over supported Pd catalysts

Lignocellulosic biomass is the most abundant and economical non-fossil carbon source. Furthermore, it is not competitive with the food chain, coming from lignocellulosic wastes including agricultural and food processing, local urban solid and forestry wastes. However, these are made up of complex carbohydrates (mainly, cellulose and hemicellulose), which require to be broken down in their respective monomers. The hemicellulose is mainly composed of pentosans, which, after an initial hydrolysis step, are dehydrated to furfural. Furfural is an important platform molecule, since it has a wide range of applications, being considered the main chemical, aside from bioethanol, obtained from the sugar platform for the synthesis of chemicals, for plastics, agrochemical and pharmaceutical industries. In the present work, the hydrogenation of furfural in gas phase has been studied by using Pd as active phase, and different metal oxides as support, in order to elucidate the influence of the support on the catalytic performance. Furfural can be converted into chemicals with important applications in many different industrial fields. Thus, reduction of furfural can proceed through different pathways depending on the experimental conditions, where the nature of the catalysts plays a key role. In the case of Pd-based catalysts, the main products come from the decarbonylation of furfural.The catalytic results reveals that the nature of the support exerts an important influence on furfural conversion and yield. The highest conversion (92% after 5 h of TOS at 463 K) was attained with a Pd-SiO2 catalyst, with a furan yield of 70 mol%. This catalyst is the most selective to furan and a moderate deactivation is only observed after 5 h reaction. The catalytic performance demonstrates that decarbonylation reaction was the main pathway, although the formation of furfuryl alcohol and 2-methylfuran also suggests that the hydrogenation of the carbonyl group of furfural takes place.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Supported nickel nitride catalysts for the gas-phase hydrogenation of furfural

A series of catalysts with different nickel loading (2.5-30 wt%) has been prepared by UGR. The preparation of Ni3N phase was ascertained via Powder X-rays diffraction together with cubic nickel . The elemental chemical analysis and XPS data confirm the presence of the nitride phase. Their catalytic performance points out that catalysts with loading of 5-10 wt% Ni exhibit a higher stability, maintaining furfural conversion values higher than 75% after 5 h of time-on-stream at 170ºC, and the main products detected were furfuryl alcohol (hydrogenation) and furan (decarbonylation). This would indicate that two types of active sites are present on the catalyst surface. It is noteworthy the high catalytic activity of this family of catalyst, since they exhibit a better performance than Cu-ZnO catalysts, but using a lower reaction temperature and H2/furfural molar ratio, as well as a higher furfural concentration and WHSV values. The experimental conditions have been optimized in order to achieve the maximum yield in the target product, but preserving a high activity and stability. The fresh and spent catalysts have been characterized in order to elucidate structure-activity-stability relationships.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec