Pola Pemanfaatan Lahan dan Faktor-faktor Perkembangan Wilayah Perkotaan di Kabupaten Sleman dan Kabupaten Bantul

Penelitian ini bertujuan untuk menganalisis pertumbuhan wilayah perkotaan, terutama dinamika wilayah periurban yang menjadi target perluasan aktivitas perkotaan, terutama permukiman. Fenomena urbanisasi kontemporer ini terjadi akibat migrasi kelompok ekonomi menengah ke pinggiran kota seiring dengan meningkatnya kepadatan pusat kota yang berdampak pada penurunan kualitas lingkungan hidup. Keinginan untuk mencari lingkungan permukiman yang lebih baik merupakan faktor pendorong utama, di samping keterbatasan lahan permukiman di pusat kota. Hasil yang didapat menunjukkan bahwa perambahan lahan di wilayah periurban telah merubah struktur ruang dan pola pemanfaatan lahan. Pada dimensi ekonomi, perkembangan aktivitas perkotaan di wilayah periurban telah memicu pergeseran struktur ekonomi primer yang berbasis potensi agraris menuju sektor jasa dan perdagangan akibat perubahan struktur sosial

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

M&S highlight: Provis (2014), geopolymers and other alkali activated materials—why, how, and what?

Materials and Environmen

Self-healing of cracks by using saturated calcium hydroxide solution to activate slag in slag cementitious materials

Structural EngineeringCivil Engineering and Geoscience

Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.Materials and Environmen

Chloride diffusivity in partially saturated cement-based materials assessed by resistivity measurements

Concrete is seldom saturated due to its self-desiccation. Even the submerged concrete structures may remain unsaturated for quite a long time. It has been reported the saturation level of pore solution has significant effect on species penetration. However, very little work was proposed regarding the transport properties and serviceability of concrete structures made of blended cementitious materials. This paper initiated the study of chloride ion diffusion in various blended cement-based system under non-saturated condition by resistivity measurements. Experiments have been performed on mortars made of different cement-based materials (Portland cement, fly ash, blast furnace slag, limestone powder) with different water to binding ratio (w/b=0.4, 0.5, 0.6). The mortar specimens have been curing for 200 days conditioning with 98% RH and 20°C, followed by oven drying at 50°C until the specimens reach different saturation levels from 95% down to 18%. The resistivity measurements for different cement-based systems are performed. The results showed that saturation level has significant effect on the chloride diffusion coefficient. As to the relation between relative diffusivity and water saturation, the effect of w/b is less obvious in system with higher w/b. Compared with FA and LP system, the deepest decrease in relative diffusivity was found in BFS-blended system with the decrease of water saturation level.Structural EngineeringCivil Engineering and Geoscience

A mathematical model in charactering chloride diffusivity in unsaturated cementitious material

In this paper, a new analytic model for predicting chloride diffusivity in unsaturated cementitious materials is developed based on conductivity theory and Nernst-Einstein equation. The model specifies that chloride diffusivity in unsaturated cementitious materials can be mathematically described as a function of chloride diffusivity in saturated state, water saturation and average pore diameter of the material. A series of experiments were conducted in order to validate the model. Mortar samples with varying cementitious mixtures were cast and cured for one year, followed by oven drying at 50 °C until desired water saturation levels (18 to 100 %) and homogeneous moisture distribution were obtained. The electrical conductivities of mortar specimens at various water saturations were measured and then converted into chloride diffusivities by using Nernst-Einstein equation. It is found that the experimental results can be well described by the analytic model proposed in this work.Materials and Environmen

Effect of Moisture Exchange on Interface Formation in the Repair System Studied by X-ray Absorption

In concrete repair systems, material properties of the repair material and the interface are greatly influenced by the moisture exchange between the repair material and the substrate. If the substrate is dry, it can absorb water from the repair material and reduce its effective water-to-cement ratio (w/c). This further affects the hydration rate of cement based material. In addition to the change in hydration rate, void content at the interface between the two materials is also affected. In this research, the influence of moisture exchange on the void content in the repair system as a function of initial saturation level of the substrate is investigated. Repair systems with varying level of substrate saturation are made. Moisture exchange in these repair systems as a function of time is monitored by the X-ray absorption technique. After a specified curing age (3 d), the internal microstructure of the repair systems was captured by micro-computed X-ray tomography (CT-scanning). From reconstructed images, different phases in the repair system (repair material, substrate, voids) can be distinguished. In order to quantify the void content, voids were thresholded and their percentage was calculated. It was found that significantly more voids form when the substrate is dry prior to application of the repair material. Air, initially filling voids and pores of the dry substrate, is being released due to the moisture exchange. As a result, air voids remain entrapped in the repair material close to the interface. These voids are found to form as a continuation of pre-existing surface voids in the substrate. Knowledge about moisture exchange and its effects provides engineers with the basis for recommendations about substrate preconditioning in practice.Structural EngineeringCivil Engineering and Geoscience

Use of rice husk ash for mitigating the autogenous shrinkage of cement pastes at low water cement ratio

It is well recognized that the high risk of early age micro-crack of HPC/UHPC is attributed to the large magnitude of early age autogenous shrinkage caused by self-desiccation in binder hydration. Over the years, several methods have been proposed to mitigate autogenous shrinkage based on internal curing theory, and a better internal curing agent is always being sought.Rice husk ash (RHA), was recognized having potencial to be an internal curing agent. In this paper, the effect of RHA on mitigating the autogenous shrinkage has been evaluated by different mean particle sizes of RHA, and the internal RH change was measured at the same situation. The results show a high efficiency of RHA for internal curing purpose, to drastically reduce the autogenous shrinkage of cement pastes. Comparing to the cement paste without RHA, the internal RH results show that the internal RH in pastes with RHA is evidently higher at either early or later ages. These were addressed in order to explain the mechanism RHA mitigates the autogenous shrinkage of pastes.Materials and Environmen

Numerical Study on Chloride Ingress in Cement-Based Coating Systems and Service Life Assessment

Chloride-induced corrosion is a critical issue for RC structures. Cement-based coatings can be used to protect concrete structures with unsatisfactory quality against chloride ingress. To evaluate the effectiveness of the coatings to extend the service life of coated concrete structures, the evolution of the chloride profile in the coated concrete structures should be determined. This paper investigated the mechanism of chloride ingress into coated concrete structures (i.e., coatings made of cement paste and concrete substrate). A numerical tool is proposed for calculating the chloride profiles in the coated concrete structures. A parametric study investigated the influence of several factors on the chloride ingress: the water:cement (w:c) ratio of the coating, the thickness of the coating, and early or late application of the coating. A preliminary cost analysis of coating materials was carried out. The results showed that the effectiveness of the coatings increased with coating thickness at a drastic increase of material cost; the effectiveness of the coatings increased with the decrease of the w:c ratio at a moderate increase of material cost. In order to extend the service life of the substrate, a coating with a low w:c ratio is recommended, and the coating thickness should be designed depending on the requirements. Moreover, the exposure history of the substrate before application of the coating also has an influence on the effectiveness of the coating. To protect an existing concrete structure exposed to a chloride environment against rapid chloride ingress, it is preferable to apply a coating as early as possible, because the effectiveness of the coating is reduced by late application.Accepted Author ManuscriptMaterials and Environmen