Industrialised Mass Housing in Saudi Arabia: A Qualitative and Technological Study

In 2017, the Saudi Arabian Government through its Ministry of Housing, announced that it planned to build 1.45 million affordable houses by 2030. The government will contribute to the cost of the houses to put them within the price range of people with modest incomes. Central to achieving this goal is the use of innovative, high-tech construction methods, mainly 3D printing. Several prototype houses have been constructed and more are planned to give Saudis an opportunity to experience them first-hand before a decision is made to go ahead with the planned rollout. The motivation for this thesis was to better understand the likely success or failure of this ambitious scheme. Early research soon revealed that since the discovery of oil in the kingdom in 1938, there have been many thousands of houses and apartments built through government-sponsored affordable housing projects. All have embodied a mixture of imported western notions of domestic living combined with traditional Saudi cultural, social and religious values and practices. The construction of these large-scale projects has relied on, and to a large extent been driven by, the use of imported construction materials, techniques and expertise. To better understand the current masshousing plan this thesis, through the study of examples and case studies, explores these projects from both a technological and a qualitative perspective. The aim is to provide insights into their successes and failures in the hope that lessons can be learned that will help guide the current proposal towards a fruitful outcome for the Saudi people for whom the houses are intended. Prior to 1938, domestic buildings in Saudi Arabia were constructed by local craftsmen using traditional materials and techniques. The first modern buildings were, flat-packed, timber houses manufactured in California and imported by the Standard Oil Company of California (SOCAL) to accommodate their expat oil workers in the rapidly expanding camp at Dammam on the Arabian Gulf. A trickle soon turned into a flood with many thousands of prefabricated timber houses from America and Europe imported into oil compounds all around the country. While these houses were never accepted more widely by Saudis as suitable domestic dwellings the modernist, technological thinking they embodied undoubtedly translated into the first contemporary, non-traditional houses built outside the camps during the 1950s designed by architects and engineers employed by SOCAL’s successor company Aramco. Mass-housing projects for the wider Saudi community soon followed all of which were constructed with heavy concrete construction. The first examples were built in situ however by the 1970s industrialised prefabrication had become established as the dominant method of delivering thousands of identical, affordable houses and apartments. Many were initially unappealing to Saudi house and apartment buyers and stood empty for a number of years. When the houses were finally occupied their new owners expressed their dissatisfaction with the manifestation of imported ideas about how they should live by almost universally carrying out modifications. These range from the relatively minor, raising the height of boundary walls, to major changes including adding a second storey. It is extremely difficult for the untrained householder or the local builder to alter and modify a house constructed of factory-made, loadbearing precast concrete panels and the same will be true for 3D printed houses. For the 1970s precast houses, modifications resulted in a significant number of structural failures leading to abandonment of the house. In addition, eclectic streetscapes emerged consisting of an assortment of styles and building materials some of which attempt to recreate a resonance with vernacular modes of living. Some houses are modelled on the latest trends found in architectural and lifestyle magazines. If minimising this level of modification is accepted as a goal for the proposed 3D printed houses, then a detailed understanding of previous industrialised mass housing schemes is important.Thesis (Ph.D.) -- University of Adelaide, School of Architecture & Built Environment, 202

Redefining the H-NS protein family: a diversity of specialized core and accessory forms exhibit hierarchical transcriptional network integration

H-NS is a nucleoid structuring protein and global repressor of virulence and horizontally-acquired genes in bacteria. H-NS can interact with itself or withhomologous proteins, but protein family diversity and regulatory network overlap remain poorly defined. Here, we present a comprehensive phylogeneticanalysis that revealed deep-branching clades, dispelling the presumption that H-NS is the progenitor of varied molecular backups. Each clade is composedexclusively of either chromosome-encoded or plasmid-encoded proteins. On chromosomes, stpA and newly discovered hlpP are core genes in specificgenera, whereas hfp and newly discovered hlpC are sporadically distributed. Six clades of H-NS plasmid proteins (Hpp) exhibit ancient and dedicatedassociations with plasmids, including three clades with fidelity for plasmid incompatibility groups H, For X. A proliferation of H-NS homologs in Erwiniaceaei ncludes the first observation of potentially co-dependent H-NS forms. Conversely, the observed diversification of oligomerization domains may facilitatestable co-existence of divergent homologs in a genome. Transcriptomic and proteomic analysis in Salmonella revealed regulatory crosstalk and hierarchical control of H-NS homologs. We also discoveredthat H-NS is both a repressor and activator of Salmonella Pathogenicity Island 1 gene expression, and both regulatory modes are restored by Sfh (HppH) in the absence of H-NS

Effect of Silver/Reduced Graphene Oxide@Titanium Dioxide (Ag/rGO@TiO2) Nanocomposites on the Mechanical Characteristics and Biocompatibility of Poly(Styrene-co-Methyl Methacrylate)-Based Bone Cement

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO2) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO2 nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO2)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO2)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO2 nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line

Biomechanical reinforcement by CAD-CAM materials affects stress distributions of posterior composite bridges:3D finite element analysis.

ObjectivesThis 3D finite element analysis study aimed to investigate the effect of reinforcing CAD-CAM bars on stress distribution in various components of a posterior composite bridge.MethodsA virtual model mimicking the absence of an upper second premolar was created, featuring class II cavity preparations on the proximal surfaces of the adjacent abutment teeth surrounding the edentulous space. Five distinct finite element analysis (FEA) models were generated, each representing a CAD-CAM reinforcing bar material: 3-YTZP (IPS. emax ZirCAD MO; Zr), lithium disilicate (IPS e.max CAD; EX), nano-hybrid resin composite (Grandio Blocs; GB), Fibre-reinforced composite (Trilor; Tri), and polyetheretherketone (PEEK). A veneering resin composite was employed to simulate the replacement of the missing premolar (pontic). In the FEA, an axial force of 600 N and a transverse load of 20 N were applied at the center of the pontic. Subsequently, maximum von Mises (mvM) and maximum principal stresses (σmax) were computed across various components of the generated models. Additionally, shear stresses at the interface between the CAD-CAM bars and the veneering resin composite were determined.ResultsCAD-CAM materials with high modulus of elasticity, such as Zr and EX, exhibited the highest mvM stresses and shear stresses while transferring the lowest stress to the veneering resin composite in comparison to other materials. Conversely, PEEK demonstrated the lowest mvM stresses but produced the highest stresses within the veneering resin composite. There was a uniform distribution of mvM stresses in the remaining tooth structure among all groups, except for a noticeable elevation in the molar region of Zr and EX groups.SignificanceReinforcing CAD-CAM bar materials with a high modulus of elasticity, such as Zr and EX, may result in debonding failures at the connector sites of posterior composite bridges. Conversely, GB, PEEK, and Tri have the potential to cause fracture failures at the connectors rather than debonding

Sub-MICs of Mentha piperita essential oil and menthol inhibits AHL mediated quorum sensing and biofilm of Gram-negative bacteria

Bacterial quorum sensing (QS) is a density dependent communication system that regulates the expression of certain genes including production of virulence factors in many pathogens. Bioactive plant extract/compounds inhibiting QS regulated gene expression may be a potential candidate as antipathogenic drug. In this study anti-QS activity of peppermint (Menthe piperita) oil was first tested using the Chromobacterium violaceum CVO26 biosensor. Further, the findings of the present investigation revealed that peppermint oil (PMO) at sub-Minimum Inhibitory Concentrations (sub-MICs) strongly interfered with acyl homoserine lactone (AHL) regulated virulence factors and biofilm formation in Pseudomonas aeruginosa and Aeromonas hydrophila. The result of molecular docking analysis attributed the QS inhibitory activity exhibited by PMO to menthol. Assessment of ability of menthol to interfere with QS systems of various Gram-negative pathogens comprising diverse AHL molecules revealed that it reduced the AHL dependent production of violacein, virulence factors, and biofilm formation indicating broad-spectrum anti-QS activity. Using two Escherichia colt biosensors, MG4/pKDT17 and pEAL08-2, we also confirmed that menthol inhibited both the las and pqs QS systems. Further, findings of the in vivo studies with menthol on nematode model Caenorhabditis elegans showed significantly enhanced survival of the nematode. Our data identified menthol as a novel broad spectrum QS inhibitor.Deanship of Scientific Research at KSUDepartment of Agricultural Microbiology, Aligarh Muslim University, Aligarh, IndiaDepartment of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi ArabiaDepartment of Zoology, Aligarh Muslim University, Aligarh, IndiaDepartment of Biochemistry, Protein Research Chair, College of Science, King Saud University, Riyadh, Saudi ArabiaSchool of Pharmaceutical Sciences, Sao Paulo State University, Araraquara, BrazilDeanship of Scientific Research at KSU: RGP-21

Redefining the H-NS protein family: a diversity of specialized core and accessory forms exhibit hierarchical transcriptional network integration

Abstract H-NS is a nucleoid structuring protein and global repressor of virulence and horizontally-acquired genes in bacteria. H-NS can interact with itself or with homologous proteins, but protein family diversity and regulatory network overlap remain poorly defined. Here, we present a comprehensive phylogenetic analysis that revealed deep-branching clades, dispelling the presumption that H-NS is the progenitor of varied molecular backups. Each clade is composed exclusively of either chromosome-encoded or plasmid-encoded proteins. On chromosomes, stpA and newly discovered hlpP are core genes in specific genera, whereas hfp and newly discovered hlpC are sporadically distributed. Six clades of H-NS plasmid proteins (Hpp) exhibit ancient and dedicated associations with plasmids, including three clades with fidelity for plasmid incompatibility groups H, F or X. A proliferation of H-NS homologs in Erwiniaceae includes the first observation of potentially co-dependent H-NS forms. Conversely, the observed diversification of oligomerization domains may facilitate stable co-existence of divergent homologs in a genome. Transcriptomic and proteomic analysis in Salmonella revealed regulatory crosstalk and hierarchical control of H-NS homologs. We also discovered that H-NS is both a repressor and activator of Salmonella Pathogenicity Island 1 gene expression, and both regulatory modes are restored by Sfh (HppH) in the absence of H-NS.</jats:p