Opportunities for rehabilitation of facades of historic buildings in Moldova with limestone elements

Most buildings of historical and architectural value located in the Republic of Moldova are built of limestone or brick. The facades are decorated with columns, semi-columns and pilasters, balusters, bas-relief, and consoles. The degradation of historic buildings over time leads to the need for rehabilitation and restoration. Often privately owned buildings are repaired with the application of modern materials without taking into account the original materials, without researching the original elements and materials. Authentic decorative elements are replaced by polyurethane foam elements, which due to their easy installation and relatively low cost, can significantly reduce the financial costs of finishing and decorating facades. The interior walls of the brick are covered with plasterboard. The exterior walls of limestone are plastered with cement-based mortar instead of lime-based mortar. In some cases, the walls were covered with polystyrene. All these replacements reduce the architectural and historical value of the buildings lead to the loss of their authenticity. In order to preserve the value of historic buildings, it is necessary to use local materials. This research examines the possibilities of using limestone both for the rehabilitation of masonry and for the restoration of the decorative elements of buildings built in the XVIII-XX centuries.

Depuration of a Freshwater Clam (Batissa Violacea) from Rewa River in Fiji Using a Bio-Filter Set-Up in Closed and Open Water Circulatory System

The effectiveness of the freshwater bivalve Batissa violacea depuration was tested in closed and open water circulatory system over a 48 h period. The closed circulatory system included a sand biofilter. Microbial levels were assessed every 4 h using Total Aerobic Plate Count (TPC) for heterotrophs and Most Probable Number (MPN) for coliforms. TPC and coliform loads in bivalve tissue reduced rapidly to low and undetectable levels in a closed circulatory system while open system showed a slower reduction. Both TPC and coliform loads remained above detectable levels throughout the depuration period. Closed system showed similar patterns of logarithmic reduction of TPC and coliforms in all cases with R2>0.95 and p<0.001. Similar results were observed for tank water however, reduction of TPC and coliforms were slower. Biofilm formation was observed in the interior walls of the aquarium tanks over 48 h in all cases. Physicochemical parameters did not show any significant change. The reduction in TPC and coliform load in B. violacea suggests that biofilter in a closed water circulatory system is a simple, cost-effective, water conserving and effective way to significantly reduce the spoilage and coliform bacterial load that is accumulated in the clams.

Acoustic design tools for estimation of sound insulation performance of wood wall and floor assemblies

The National Building Code of Canada 2015 stipulates the minimum requirements of the airborne sound insulation transmission through common interior walls and ceiling/floor assemblies. The required minimum Apparent Sound Transmission Class (ASTC) is 47 in Canada, whereas the Impact Insulation Class (IIC) for floors is recommended to be higher than 55. For many years, significant efforts were made to develop sound insulation prediction models or tools to predict the sound insulation performance of wall and floor/ceiling assemblies at the design phase in order to meet the requirements and the recommendations made by codes. However, today few models can provide a reliable acoustics design tool. In this document, three prediction tools thought to be practically useful are presented and evaluated. Between these three prediction tools, one is an analytical model of the Insul software while the other two are empirical models developed by the National Research Council of Canada and the American Wood Council. This paper compared the STC and IIC ratings of wood wall and floor assemblies estimated by these three models and verified them by the measured STC and IIC ratings. This work aims at providing an idea for readers to choose a suitable design tool to proceed with their acoustic designs.

MRT-LBM simulation of natural convection in square annulus with a porous coating: Route to chaos

In this work, multiple-relaxation-time lattice Boltzmann method is applied for examining the transient natural convection in a square annulus of circular interior cylinder. This duct is covered by a porous deposit on all interior walls. The Darcy-Brinkman-Forchheimer model is implemented to model the momentum equations in the porous matrix and the Boussinesq assumption is assumed for the buoyancy force term. The influence of Darcy number (10−6 ≤ Da ≤ 10−2), Rayleigh number (103 ≤ Ra ≤ 106), radius ratio of the circular cylinder (0.05 ≤ R ≤ 0.40) and the thickness of the porous layer (0.05 ≤  ≤ 0.15) on natural convection are analysed. The results are reported in the form of streamlines, isotherms and average Nusselt number. In addition, temporal evolution and phase portrait are plotted to examine the unsteady flow at elevated Rayleigh numbers. The results are coherent and show that natural convection develops from stable state to chaotic flow via periodic and quasi-periodic oscillatory regimes as the Rayleigh number increases.

White Light —White Heat: The use of Fire as a Light and Heat Source in an Atrium House in Roman Pompeii

This article concerns the distribution of fire as light and heat source within the insula investigated by the ongoing Swedish Pompeii Project. Here the author suggests that fire installations as kitchens, ovens and baths were clustered in specific areas within this insula, and the installations were not efficiently used to heat the dwelling areas of the house. It is also proposed that the surfaces of the interior walls and floors of the Roman atrium house were polished in purpose to reflect and distribute light and, which is emphasised in the article, to soften the transition between brightly lit areas and areas in dark shadow. This contrast had to be eliminated for the human eye to adopt to the light conditions in the room and by that, to make the light as efficient as possible.

Feed or feed transport as the potential route for a porcine epidemic diarrhea outbreak in a 10,000-sow breeding herd in Mexico

Porcine epidemic diarrhea virus (PEDV) produces infection in pigs characterized by vomiting and diarrhea. PEDV is transmitted via oral-fecal and a very low oral dose is enough to infect susceptible pigs, causing devastating consequences in production. A 10,000-sow farrow-to-wean farm located in northwest Mexico was infected with PEDV. After the observation of the first clinical signs, an outbreak investigation take into place to determine the most probably source of infection. A systematic collection of samples including rectal swabs, gestation and lactation feed, surface swabs from the interior or feed bins and many points of the feed truck delivering the implicated feed was performed. Samples were tested for PEDV polymerase chain reaction (PCR). Positive PCR results showed the evidence of PEDV RNA in lactating feed, the interior walls of the feed bins and in the interior of the auger boom of the feed truck. This, connected with the location of first clinical signs point that the most probably incursion of PEDV in to this breeding herd was contaminated feed. This paper shows how feed or feed transport can be a potential source of PEDV infection in farms and highlight the importance of stablishing biosecurity programs to mitigate the risk of PEDV infections.

Spectroscopic Investigation of Wall Paintings in the Alhambra Monumental Ensemble: Decorations with Red Bricks

The Alhambra Monumental Ensemble (Granada, Spain) is a unique well-preserved palatine city from the medieval Islamic period, and it constitutes the best example of Nasrid architecture. In this work, we focus on the study of one of its most unknown decorations: Wall paintings with the appearance of red bricks. These faux-brick decorations are found in many different locations within the Alhambra complex, including both exterior and interior walls, arches and vaults. We have considered locations from different Nasrid reigns to gain information about their characteristics in terms of materials, execution techniques and conservation state. They have been studied combining a non-invasive methodology using portable equipment (X-ray fluorescence (XRF) and Raman spectroscopy) with complementary studies on selected samples (Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) and Raman microimaging). In general, those located in the exterior are poorly preserved, in contrast with the good conservation state of the interior motifs. The red rectangles of these decorations were painted over a white finishing layer, which acted also as the edge lines between these false bricks. The red colour was always due to hematite (α-Fe2O3), as revealed by its characteristic Raman bands. The use of a natural red ochre pigment (very abundant in the region) could be hypothesised considering XRF and SEM-EDS results. In general, the white layer was made of lime mortar and the presence of CaCO3 in the painting layers suggests the use of lime-based techniques (either fresco or mezzo fresco). Only in one of the indoor locations, a different execution technique, based on gypsum (CaSO4·2H2O) plaster, was used. The identification of calcium oxalate in this location, in the form of weddellite (CaC2O4·2H2O), can be interpreted as the result of organic binder degradation. Furthermore, superficial contamination with gypsum was always detected in outdoor locations.

Testing the Toxicity of Stachybotrys chartarum in Indoor Environments—A Case Study

Infestation of interior walls of buildings with fungal mould is a reason for health concern which is exacerbated in energy-efficient buildings that limit air circulation. Both mycological and mycotoxicological studies are needed to determine the potential health hazards to residents. In this paper, a rare case of the occurrence of Stachybotrys chartarum in an apartment building in the Lubuskie Province in Poland has been described. Isolated as the major constituent of a mixed mycobiota, its specific health relevance still needs to be carefully analyzed as its biochemical aptitude for the synthesis of mycotoxins may be expressed at different levels. Therefore, ecotoxicological tests were performed using two bioindicators: Dugesia tigrina Girard and Daphnia magna Straus. D. tigrina was used for the first time to examine the toxicity of S. chartarum. The ecotoxicological tests showed that the analyzed strain belonged to the third and fourth toxicity classes according to Liebmann’s classification. The strain of S. chartarum was moderately toxic on Potato Dextrose Agar (PDA) as a culture medium (toxicity class III), and slightly toxic on Malt Extract Agar (MEA) (toxicity class IV). Toxicity was additionally tested by instrumental analytical methods (LC-MS/MS). This method allowed for the identification of 13 metabolites (five metabolites reported for Stachybotrys and eight for unspecific metabolites). Spirocyclic drimanes were detected in considerable quantities (ng/g); a higher concentration was observed for stachybotryamide (109,000 on PDA and 62,500 on MEA) and lower for stachybotrylactam (27,100 on PDA and 46,300 on MEA). Both may explain the result observed through the bioindicators. Highly toxic compounds such as satratoxins were not found in the sample. This confirms the applicability of the two bioindicators, which also show mutual compatibility, as suitable tools to assess the toxicity of moulds.

Design and implementation of automatic painting mobile robot

Wall painting is a repetitive, stressful, and hazardous process that makes it an ideal automation case. In the automotive industry, painting had been automated but not yet for the construction industry. However, there is a strong need for a mobile robot that can move to paint residential interior walls. In this study, we aim to design and implement an automatic painting mobile robot. The conceptual design of the proposed wall painting robot consisting paint mechanism with a spray gun and ultrasonic sensor. The spray gun is attached to a pulley mechanism that has linear motion. The ultrasonic sensor is used to detect the spray gun when it reached a certain limit. The DC motor rotates clockwise and counterclockwise based on the ultrasonic sensor condition made. The experimental results indicate that the robot was able to paint the walls smoothly vertically, and horizontally. The spraying gun structure's speed is at a tolerable speed of 0.07 m/s, which could be increased, but to provide high-quality painting without any gaps, the current speed was selected as the most suitable, without any harm to the working process.

Laser Scanning Based Surface Flatness Measurement Using Flat Mirrors for Enhancing Scan Coverage Range

Surface flatness is an important indicator for the quality assessment of concrete surfaces during and after slab construction in the construction industry. Thanks to its speed and accuracy, terrestrial laser scanning (TLS) has been popularly used for surface flatness inspection of concrete slabs. However, the current TLS based approach for surface flatness inspection has two primary limitations associated with scan range and occluded area. First, the areas far away from the TLS normally suffer from inaccurate measurement caused by low scan density and high incident angle of laser beams. Second, physical barriers such as interior walls cause occluded areas where the TLS is not able to scan for surface flatness inspection. To address these limitations, this study presents a new method that employs flat mirrors to increase the measurement range with acceptable measurement accuracy and make possible the scanning of occluded areas even when the TLS is out of sight. To validate the proposed method, experiments on two laboratory-scale specimens are conducted, and the results show that the proposed approach can enlarge the scan range from 5 m to 10 m. In addition, the proposed method is able to address the occlusion problem of the previous methods by changing the laser beam direction. Based on these results, it is expected that the proposed technique has the potential for accurate and efficient surface flatness inspection in the construction industry.