Biological Stabilisers in Earthen Construction: A Mechanistic Understanding of their Response to Water-Ingress

2022 ◽  
Author(s):  
Yask Kulshreshtha ◽  
Philip J. Vardon ◽  
Yi Du ◽  
Guillaume Habert ◽  
Aurélie Vissac ◽  
...  
Keyword(s):  
Water Resistance ◽  
Embodied Energy ◽  
Physical Factors ◽  
Cow Dung ◽  
Widespread Application ◽  
Hydraulic Lime ◽  
Water Ingress ◽  
Wide Range ◽  
Earthen Construction ◽  
Response To Water

Earthen construction is re-gaining popularity as an ecological and economical alternative to contemporary building materials. While building with earth offers several benefits, its performance due to water ingress is a concern for its widespread application. This limitation is often solved by adding chemical stabilisers such as Portland cement and hydraulic lime. Chemical stabilisers are a subject of widespread debate as they increase the cost and embodied energy of the structure, and reduce the desirable characteristics of raw or unstabilised earth. This along with perceived environmental performance, renewability, and proven effectiveness in traditional earthen construction has led to a growing interest in biological or organic stabilisers. Although the strengthening mechanism of biological stabilisers is widely covered in scientific studies, discussion regarding the water-resistance is limited. This review aggregates the research from the field of earthen construction and geotechnical engineering and extends it to explain the possible mechanism responsible for the water-resistance behaviour of biologically stabilised earthen materials. This study includes a wide range of traditional and industrial biological stabilisers derived from animals (cow-dung, casein, chitosan), plants (starch, guar gum, cactus mucilage, lignin, tannin) seaweeds (alginate, agar, carrageen) and microbes (xanthan gum, gellan gum). A conceptual model of water-ingress in unstabilised earthen blocks is proposed and the response of biological stabiliser to water ingress and related physico-chemical and physical factors is discussed using the model at microscale (stabiliser interaction with clay, sand) and macroscale (hydraulic conductivity of block). Properties of stabilisers such as hydrophobicity, stability under wet conditions or interaction with cations have a dominant effect on the overall response to water ingress. Key gaps have been identified in the existing knowledge that are necessary to investigate in order to understand the water-resistance behaviour comprehensively. The study concludes with a brief assessment of biological stabilisers based on their performance and feasibility to use in contemporary earthen construction.

scholarly journals A surrogate virus neutralization test to quantify antibody-mediated inhibition of SARS-CoV-2 in finger stick dried blood spot samples

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Amelia E. Sancilio ◽  
Richard T. D’Aquila ◽  
Elizabeth M. McNally ◽  
Matthew P. Velez ◽  
Michael G. Ison ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Venous Blood ◽  
Host Cells ◽  
Dried Blood Spot ◽  
Blood Collection ◽  
Widespread Application ◽  
Live Virus ◽  
Dilution Series ◽  
Wide Range ◽  
Blood Spot

AbstractThe spike protein of SARS-CoV-2 engages the human angiotensin-converting enzyme 2 (ACE2) receptor to enter host cells, and neutralizing antibodies are effective at blocking this interaction to prevent infection. Widespread application of this important marker of protective immunity is limited by logistical and technical challenges associated with live virus methods and venous blood collection. To address this gap, we validated an immunoassay-based method for quantifying neutralization of the spike-ACE2 interaction in a single drop of capillary whole blood, collected on filter paper as a dried blood spot (DBS) sample. Samples are eluted overnight and incubated in the presence of spike antigen and ACE2 in a 96-well solid phase plate. Competitive immunoassay with electrochemiluminescent label is used to quantify neutralizing activity. The following measures of assay performance were evaluated: dilution series of confirmed positive and negative samples, agreement with results from matched DBS-serum samples, analysis of results from DBS samples with known COVID-19 status, and precision (intra-assay percent coefficient of variation; %CV) and reliability (inter-assay; %CV). Dilution series produced the expected pattern of dose–response. Agreement between results from serum and DBS samples was high, with concordance correlation = 0.991. Analysis of three control samples across the measurement range indicated acceptable levels of precision and reliability. Median % surrogate neutralization was 46.9 for PCR confirmed convalescent COVID-19 samples and 0.1 for negative samples. Large-scale testing is important for quantifying neutralizing antibodies that can provide protection against COVID-19 in order to estimate the level of immunity in the general population. DBS provides a minimally-invasive, low cost alternative to venous blood collection, and this scalable immunoassay-based method for quantifying inhibition of the spike-ACE2 interaction can be used as a surrogate for virus-based assays to expand testing across a wide range of settings and populations.

Influence of Sample Thickness and Capping on Characterization of Bedding Mortars from Historic Masonries by Double Punch Test (DPT)

2014 ◽  
Vol 624 ◽  
pp. 322-329 ◽  
Author(s):  
Enrico Sassoni ◽  
Elisa Franzoni ◽  
Claudio Mazzotti
Keyword(s):  
Compressive Strength ◽  
Poor Quality ◽  
Sample Thickness ◽  
Mortar Sample ◽  
Hydraulic Lime ◽  
Punch Test ◽  
Natural Hydraulic Lime ◽  
Wide Range ◽  
Surface Capping

For determination of compressive strength of bedding mortar used in historic masonries, a promising moderately-destructive technique is double punch test (DPT). DPT consists of loading prismatic samples of mortar (about 4×4×1 cm3) by means of two circular steel platens (typically 2 cm diameter) and then calculating mortar compressive strength as the ratio of the failure load to the cross section of the circular platens. In this study, the influence of mortar sample thickness and mortar sample capping on the reliability of results obtained by DPT was systematically investigated. The influence of sample thickness was assessed by comparing DPT results obtained for samples with 5, 10, 15 and 20 mm thickness with compressive strength determined by testing reference 4 cm-side cubes. Different mortars were considered (cement, lime-cement, natural hydraulic lime), in order to investigate a wide range of mortar mechanical characteristics. The influence of surface capping was evaluated on a lime-cement mortar by comparing compressive strength determined on reference cubes with strength obtained by DPT on proper samples, without capping and after capping with rubber, gypsum and cement. The results of the study indicate that sample thickness substantially influences mortar compressive strength determined by DPT, which may vary by up to three times depending on sample thickness. A good estimation of the actual mortar compressive strength was obtained when samples with thickness similar to the loading platens diameter were tested, which suggests that choosing the size of the loading platens for DPT based on the thickness of mortar joints under investigation may be an effective way for obtaining reliable estimations. As for the influence of surface capping, in those cases where no mortar sample regularization is possible, because of the poor quality of the mortar, the results of the study indicate that sample capping actually seems necessary in order to avoid significant underestimations of mortar compressive strength. Considering the higher practicality offered by gypsum with respect to rapid-setting cement for surface capping, the use of gypsum seems preferable.

scholarly journals Combinatorial microfluidic droplet engineering for biomimetic material synthesis

2016 ◽  
Vol 2 (10) ◽  
pp. e1600567 ◽  
Author(s):  
Lukmaan A. Bawazer ◽  
Ciara S. McNally ◽  
Christopher J. Empson ◽  
William J. Marchant ◽  
Tim P. Comyn ◽  
...  
Keyword(s):  
General Strategy ◽  
Emulsion Droplet ◽  
Material Synthesis ◽  
Widespread Application ◽  
Carrier Fluid ◽  
Wide Range ◽  
In Vitro Protein Expression ◽  
Selection Of ◽  
Vitro Protein

Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach uses a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials, and medicine.

Some factors influencing landholder opinion of the native grass Microlaena stipoides

2004 ◽  
Vol 26 (2) ◽  
pp. 178 ◽  
Author(s):  
Catherine Allan ◽  
R. D. B. Whalley
Keyword(s):  
Physical Factor ◽  
Annual Rainfall ◽  
Physical Factors ◽  
Value Judgments ◽  
Actual Performance ◽  
Ecotypic Variation ◽  
Factors Influencing ◽  
Divergence Of Opinion ◽  
Wide Range ◽  
Microlaena Stipoides

Microlaena stipoides is widespread in the higher rainfall areas of Australia. It is consistently reported in the literature as providing high quality forage, yet anecdotal evidence suggests a wide range of opinions about the value of M. stipoides among graziers who manage areas with abundant M. stipoides. This paper addresses three questions relating to this divergence of opinion. Are landholders responding to inherent variability within M. stipoides? Is M. stipoides responding to different site and management conditions, prompting landholders to value it preferentially where site or management suit? Or are the landholders' judgments of M. stipoides influenced less by the actual performance of the grass on their properties than by social factors? Data collected from ten properties in the Victorian Upper Murray included a morphological assessment of M. stipoides samples, quantitative site and pasture information and qualitative data from interviews with property managers. Ecotypic variation and responses to site and management variables were found, but there were no apparent relationships between these parameters and the value judgments made by the landholders. The only physical factor which appeared to have any influence on landholder opinion was the annual rainfall for their property, although this was not through direct impact on other site attributes. It seems that social rather than physical factors may need to be explored in order to understand the factors influencing landholder opinion of M. stipoides.

Cost and environmental impacts reduction through building compactness

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andrea Parisi Kern ◽  
Renata Postay ◽  
Eduardo Reuter Schneck ◽  
Mauricio Mancio ◽  
Marco Aurélio Stumpf González ◽  
...  
Keyword(s):  
Environmental Impacts ◽  
Construction Materials ◽  
Embodied Energy ◽  
Constructive Method ◽  
Emission Data ◽  
Content Type ◽  
Wide Range ◽  
The Cost ◽  
Research Stage ◽  
Compactness Index

PurposeThe central motivation for this study was to examine alternatives against the apartment area reduction as a safe way to reduce construction costs, adopted by many construction companies. From the building economic compactness index concept, it was studied the cost and environmental impacts (material consumption, embodied energy – EE and CO2 emission).Design/methodology/approachThe research strategy takes advantage of a case study aiming to investigate the relation between design characteristics related to area (m²) and building economic compactness index (%) with cost (Research Stage 1) and with environmental impacts: (Research Stage 2). The study involved real data from social housing projects, chosen in terms in terms of very similar features like size, area and constructive method (constants), however, with dissimilar compactness (variable).FindingsThe lack of direct relation between area and cost signs the importance of including the cost of vertical plans considered in the economic compactness building. The higher the economic compactness index, the lower the cost, the lower the amount of material, EE and CO2 emission parameters. However, due to the wide range of EE and CO2 values available, the reduction in the amount of materials achieved by increasing building economic compactness index may not be reflected in EE and CO2 gains.Research limitations/implicationsAs the limitation of this study, it must be taken into account a limited number of case buildings and the fact that the analysis is dependent on the reliability and accuracy of the data provided by constructors and the available information of EE and CO2 emission. As well discussed in the literature, the consistent database is a great challenge for the construction sector.Originality/valueThere might be alternatives to higher areas with relatively low-cost increments since results from buildings with the same area present different cost estimative and suggest a strong relationship with the economic compactness index. The large variation of EE and CO2 emission data indicates that reductions obtained by compactness increase may be impaired if the construction materials are produced with high levels of EE and CO2 emission. Thus, there must be an integrated effort on the part of designers (design and material specification) and manufacturers (material production), since isolated solutions may not be enough.

scholarly journals Embodied Energy and CO2 Emissions of Widely Used Building Materials: The Ethiopian Context

Buildings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 136 ◽  
Author(s):  
Woubishet Zewdu Taffese ◽  
Kassahun Admassu Abegaz
Keyword(s):  
Co2 Emissions ◽  
Building Materials ◽  
Construction Materials ◽  
Developed Countries ◽  
Embodied Energy ◽  
Policy Makers ◽  
Coarse Aggregates ◽  
Human Habitat ◽  
Wide Range ◽  
Concrete Blocks

Buildings use a wide range of construction materials, and the manufacturing of each material consumes energy and emits CO2. Several studies have already been conducted to evaluate the embodied energy and the related CO2 emissions of building materials, which are mainly based on case studies from developed countries. There is a considerable gap in cases of developing countries regarding assessment of embodied energy and CO2 emissions of these building materials. This study identified the top five most used construction materials (cement, sand, coarse aggregates, hollow concrete blocks, and reinforcement bars), which are also prime sources of waste generation during construction in the Ethiopian building construction sector. Then, what followed was the evaluation of the embodied energies and CO2 emissions of these materials by examining five commercial and public buildings within the cradle-to-site lifecycle boundary. The evaluation results demonstrated that cement, hollow concrete blocks (HCB), and reinforcement bars (rebars) are the major consumers of energy and major CO2 emitters. Cumulatively, they were responsible for 94% of the embodied energy and 98% of the CO2 emissions. The waste part of the construction materials has inflated the embodied energy and the subsequent CO2 emissions considerably. The study also recommended several strategies for the reduction of embodied energy and the related CO2 emissions. The research delivers critical insights into embodied energy and CO2 emissions of the five most used building materials in the Ethiopian construction industry, as there are no prior studies on this theme. This might be a cause to arouse awareness and interest among the policy makers and the wider public to clearly understand the importance of research on this crucial issue to develop national energy and CO2 descriptors for construction materials, in order to take care of our naturally endowed, but yet fragile, human habitat.

scholarly journals Identifying the cause of thermal droop in GaInN-based LEDs by carrier- and thermo-dynamics analysis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dong-Pyo Han ◽  
Gyeong Won Lee ◽  
Sangjin Min ◽  
Dong-Soo Shin ◽  
Jong-In Shim ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Complex Dynamics ◽  
Physical Factor ◽  
Physical Factors ◽  
Temperature Dependent ◽  
Light Emitting ◽  
Carrier Lifetimes ◽  
Driving Current ◽  
Wide Range ◽  
Thermal Droop

Abstract This study aims to elucidate the carrier dynamics behind thermal droop in GaInN-based blue light-emitting diodes (LEDs) by separating multiple physical factors. To this end, first, we study the differential carrier lifetimes (DCLs) by measuring the impedance of a sample LED under given driving-current conditions over a very wide operating temperature range of 300 K–500 K. The measured DCLs are decoupled into radiative carrier lifetime (τR) and nonradiative carrier lifetime (τNR), via utilization of the experimental DCL data, and then very carefully investigated as a function of driving current over a wide range of operating temperatures. Next, to understand the measurement results of temperature-dependent τR and τNR characteristics, thermodynamic analysis is conducted, which enables to look deeply into the temperature-dependent behavior of the carriers. On the basis of the results, we reveal that thermal droop is originated by the complex dynamics of multiple closely interrelated physical factors instead of a single physical factor. In particular, we discuss the inherent cause of accelerated thermal droop with elevated temperature.

scholarly journals Forming mechanism of a seedling tray comprised of lignocellulose in cow manure

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3543-3562
Author(s):  
Bo Zhang ◽  
Wei Zhang ◽  
Yongcai Ma ◽  
Liqiang Qi ◽  
Jianfei Shi
Keyword(s):  
Water Resistance ◽  
Testing Machine ◽  
Compression Molding ◽  
Glass Transition Point ◽  
Cow Dung ◽  
Cow Manure ◽  
Maize Seedlings ◽  
Forming Mechanism ◽  
Universal Testing ◽  
Before And After

A new method for producing biomass seedling trays with cow manure was developed based on heating to above the glass transition point of the lignin in cow dung. The maize seedling tray, manufactured through heat compression molding, could potentially meet the demand for transplanting maize seedlings. A scanning electron microscope and universal testing machine were used to compare the changes in the internal structure and mechanical properties of the seedling tray before and after the seeding period through a compression molding technique at normal temperature before seeding and a heat compression molding technique after seeding. The results showed that the strength of the seedling tray was mainly derived from the mechanical setting force of the fiber laminated in the seedling tray. Meanwhile, the moisture in the seedling tray hindered the lignin from filling in the gaps between the stem fibers in cow manure, as well as it reduced the protective effect of lignin on the laminated inlay structure of the stem fibers in cow manure. Therefore, under the premise that the material could be completely filled in the mold, the study concluded that a lower moisture content resulted in better strength and water resistance of the seedling tray. As such, this study provides an idea for the functional utilization of cow manure.

scholarly journals Effect of feed slurry dilution and total solids on specific biogas production by anaerobic digestion in batch and semi-batch reactors

2021 ◽  
Author(s):  
Gautham P. Jeppu ◽  
Jayalal Janardhan ◽  
Shivakumara Kaup ◽  
Anish Janardhanan ◽  
Shakeib Mohammed ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Substrate Inhibition ◽  
Cattle Dung ◽  
Cow Dung ◽  
Batch Reactors ◽  
Dilution Ratio ◽  
Total Solids ◽  
State Process ◽  
Wide Range

AbstractBiomass from various sources such as cow dung is a significant source of renewable energy (as biogas) in many regions globally, especially in India, Africa, Brazil, and China. However, biogas production from biomass such as cattle dung is a slow, inefficient biochemical process, and the specific biogas produced per kg of biomass is relatively small. The improvement of specific biogas production efficiency using various dilution ratios (and, hence, total solids [TS]) is investigated in this work. A wide range of feed dilution (FD) ratios of cow dung: water (CD: W) was tested in batch biogas digesters with total solids ranging from 1% to 12.5% and FD ratio ranging from 2:1 to 1:20. To further verify the results from the above batch experiments, semi-batch experiments representative of field-scale biodigesters were conducted. Semi-batch reactors have a steady-state process, unlike batch reactors, which have an unsteady state process. Our results suggested that specific biogas production (mL/g VS) increased continuously when the total solids decreased from 12.5% to 1% (or when dilution increased). Our experiments also indicate that the commonly used 1:1 feed dilution ratio (TS ~ 10% for cow dung) does not produce the maximum specific biogas production. The possible reason for this could be that anaerobic digestion at higher total solids is rate limited due to substrate inhibition, mass transfer limitations, and viscous mixing problems that arise at higher total solids concentration. Hence, a higher feed dilution ratio between 1:2 and 1:4 (TS between 4 and 6.7%) is recommended for a more efficient biomass utilization of cowdung. Empirical relationships were also developed for variation of specific biogas yield with the total solids content of the cow dung slurry. Graphic abstract

scholarly journals EFFICIENCY IMPROVEMENT OF THE CYCLIC STEAM TREATMENT OF WELLS IN THE UPPER PERMIAN DEPOSIT OF THE USINSKOYE FIELD BASED ON THE HYDRODYNAMIC MODEL

2020 ◽  
Vol 20 (2) ◽  
Author(s):  
Maksim B. Savchik ◽  
◽  
Daria V. Ganeeva ◽  
Aleksei V. Raspopov ◽  
◽  
...  
Keyword(s):  
Oil Recovery ◽  
Steam Injection ◽  
High Viscosity ◽  
Steam Treatment ◽  
Upper Permian ◽  
Physical Factors ◽  
Thermal Methods ◽  
Optimum Parameters ◽  
Wide Range ◽  
Permian Deposit

Development of the Upper Permian high viscosity oil deposit is expected to involve thermal methods of enhanced oil recovery, in particular, cyclic steam treatment of wells. The simulator used for the deposit modeling is to be capable of computing the change in the rock fluid thermal properties, and of solving the heat and mass transfer equations. The modeling of the cyclic steam treatments used CMG STARS, a numerical simulator with a wide range of applications including modeling of thermal processes. The cyclic steam treatment includes three basic stages, such as the steam injection period, the soak period, and the production period. The number of cycles has been selected by computation on the basis of an optimum well operation. To determine the optimum quantity, computations with 7, 5 and 3 cycles were performed. Another predictive computation was performed for a well operation without cyclic steam treatments. The computations helped to determine the operation scenario with the highest cumulative oil production. During the assessment of the cyclic steam treatment efficiency by using hydrodynamic modeling, we obtained dependencies on a number of geological and physical factors, such as steam dryness fraction, formation thickness, steam injection rate, soaking time. The numerical experiments resulted in conclusions and recommendations concerning the case-by-case approach to selecting optimum parameters of the cyclic steam treatments for each individual well, taking into account the structure and specific features. Factor analysis was used to select the optimum parameters for the cyclic steam treatment of the wells drilled in the Upper Permian deposit of the Usinskoye field. For comparison, three predictive scenarios of the well operation have been computed. Cost-performance indicators of the well operation scenarios in the Upper Permian deposit of the Usinskoye field were evaluated, assuming that the wells will be operated in conditions of the natural recovery drive and multiple cyclic steam treatments, in the baseline and recommended scenarios.

Sign in / Sign up

Export Citation Format

Share Document