Biotechnologies and bioinspired materials for the construction industry : an overview

Published online: 16 Oct 2013Looking back to less than three centuries of industrialization, responsible for alarming levels of pollution and consumption of non-renewable resources that has led to the exhaustion of the earth’s capacity, the humankind only now begins to grasp the overwhelming potential of natural systems. During almost 40 million centuries, Nature has developed materials and processes with optimal performance which are totally biodegradable. Analysis of bioinspired materials requires the knowledge of both biological and engineering principles which are being a part of a large research area termed biotechnology. This hot area is one of the six strategic Key Enabling Technologies that will be funded under the EU Framework Programme Horizon 2020. This paper reviews the current knowledge on the potential of this emerging field, particularly in the development of materials and technologies for the construction industry. It covers the use of bacteria for enhancing concrete durability and for soil stabilization. It also covers bioinspired tough composite materials, bioinspired adhesives and coatings, and self-cleaning materials. Incorporation of biology basics in the civil engineering curriculum would ease the communication between biologists and civil engineers, helping to foster research on biotechnologies and bioinspired materials for the construction industry

Use of CO2-induced siderite and dolomite with nanoclay for soil improvement

We studied the precipitation of carbonate minerals used as cements for ground improvement. The carbonate minerals were prepared by combining divalent ions (Mg2+, Ca2+, and Fe2+) with carbonate ions (CO3 2-) induced by microbial activity. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) analyses observed the shapes and sizes of the minerals and attested the formation of dolomite (CaMg (CO3)2) and siderite (FeCO3). Consolidated drained triaxial tests (CD) were performed on treated specimens of silica sand with the CO2-induced siderite and dolomite cements with and without the addition of nanoclay. Specimens treated with siderite had higher strengths than dolomitetreated specimens. The addition of nanoclay further increased the shear strength of the specimens and reduced their brittleness. Moreover, it was found that the shearing resistance of fully saturated specimens was not considerably reduced compared to that of dry specimens, as it only decreased by 5–15% compared to that of dry specimens

Application of CO2 -induced carbonate minerals for soil treatment

This research used carbonate minerals generated through the capture of CO2 as an eco-friendly binder to enhance engineering properties of soils. The carbonate binders were formed by combining free carbonate ions (CO32-) obtained from CO2 capture and Fe2+ (from FeCl2) and Ca2+ (from CaCl2), which produced CaFeCO3 and FeCO3 carbonate minerals. These minerals were employed to enhance the engineering characteristics of a granular soil and were detected by Scanning Electron Microscope (SEM) analysis in the treated soil specimens. Results of uniaxial compressive strength (UCS) tests conducted under dry conditions showed that soil specimens treated with CaFeCO3 exhibited a higher strength compared to those treated with FeCO3. Generally, both types of carbonate minerals appear to have led to cementation of the treated specimens, responsible for the observed strength gain

Attitude of nurses towards euthanasia: a cross-sectional study in Iran

Background: Nurses play a major role in providing end-of-life care, and euthanasia is considered to be one of the most important ethical challenges that care providers can face. Aim: To assess the nurses' attitude towards euthanasia in Iran. Methods: The cross-sectional study included nurses who worked in intensive and critical care, as well as dialysis units of a teaching hospital affiliated to Zahedan University of Medical Sciences, who were selected by the census sampling technique. Data were collected using a two-part questionnaire encompassing the demographic characteristics of nurses and the 20-item Euthanasia Attitude Scale. Results: The overall score of nurses' attitudes towards euthanasia, ranging from one to five, was 2.71 +/- 0.45, indicating a negative attitude and opposition towards euthanasia. Alongside this, the results demonstrated that there was no significant relationship between demographic characteristics and nurses' attitudes toward euthanasia. Conclusion: In general, nurses in Iran oppose euthanasia. This can be attributed to the context of religious beliefs and culture in Iran as an Islamic country

Numerical investigation of the anisotropic behavior of the sand in drained condition

The behavior of natural soils is often anisotropic. But in practice, the mechanical behavior of soils is usually assumed to be isotropic. In recent years, various constitutive models have been developed that incorporate the anisotropic behavior of soils. But most of these constitutive models cannot take into account all aspects of anisotropy. On the other hand, these models are mostly complex and several parameters are needed to be determined to define the model. Therefore, using these models in practical matters is difficult. In this study, a simple method is presented to study the anisotropic behavior of sands in drained condition. Hollow cylinder torsion tests are modeled using commercial finite element software ABAQUS. The Modified Drucker−Prager/Cap constitutive model is used to define the soil characteristics. This constitutive model is a practical model which is widely used in numerical analyses of geotechnical problems, assuming that the soil has an isotropic behavior. In order to study the effect of soil anisotropy on the shear strength and stress-strain behavior, USDFLD subroutine is used in ABAQUS software. A new subroutine, called USDANISO, was also developed that links soil mechanical parameters to the major principal stress direction in each element, separately. Therefore, when analyzing the model, soil parameters in different soil elements can change as the major principal stress direction rotates. The hollow cylinder geometry is modeled in ABAQUS software and different combinations of shear and normal stresses are applied to investigate the behavior of modeled samples under the principal stresses with different directions. In the numerical model, stress paths similar to experimental studies (hollow cylinder torsion tests), including different values of intermediate principal stress ratio, are applied to study the anisotropic behavior of soil. The results of numerical modeling are compared with the experimental results of hollow cylinder torsion tests. The obtained results show appropriate agreement with experimental studies. Nevertheless, the method, described in this study, can be an efficient and practical method to consider the effect of major principal stress direction and intermediate principal stress ratio on the mechanical behavior of sand in drained condition

The prevalence of food insecurity in Iranian women: A study in Zahedan (Southwest of Iran)

Food insecurity is major public health issues related to nutrition. Addition of health associated with socialeconomic damaging status. This study aimed to determine Prevalence of Food insecurity in Iranian Women: A Study in Zahedan (Southwest of Iran). In this cross sectional study has been done on 1250 women at 15 to 50 in 2014 in Zahedan were examined by multistage sampling. Data collect by questionnaires Food security was measured at the household level. A locally-adapted HFIAS developed by USAID's Food and Nutrition Technical Assistance (FANTA) project was used in measuring food security in each household. Data analyzed by descriptive statistics and chi-square tests in Spss 16 software. The mean age of studying women were 28.19 ±6.71. Based on the results, 7/63 of the subjects in terms of food security was safe, 17.8 experienced food insecurity without hunger, and 12.1 reported food insecure with moderate hunger with and 4.6 of subjects experienced Food insecure with severe hunger. According to increasing food insecurity especially women and its influences in health, psychological, social and economic status in society, planning through measures to improve the economic situation and household dietary patterns of household is necessary

Rhamnose synthase activity is required for pathogenicity of the vascular wilt fungus Verticillium dahliae

The initial interaction of a pathogenic fungus with its host is complex and involves numerous metabolic pathways and regulatory proteins. Considerable attention has been devoted to proteins that play a crucial role in these interactions, with an emphasis on so-called effector molecules that are secreted by the invading microbe to establish the symbiosis. However, the contribution of other types of molecules, such as glycans, is less well appreciated. Here, we present a random genetic screen that enabled us to identify 58 novel candidate genes that are involved in the pathogenic potential of the fungal pathogen Verticillium dahliae, which causes vascular wilt diseases in over 200 dicotyledonous plant species, including economically important crops. One of the candidate genes that was identified concerns a putative biosynthetic gene involved in nucleotide sugar precursor formation, as it encodes a putative nucleotide-rhamnose synthase/epimerase-reductase (NRS/ER). This enzyme has homology to bacterial enzymes involved in the biosynthesis of the nucleotide sugar deoxy-thymidine diphosphate (dTDP)-rhamnose, a precursor of L-rhamnose, which has been shown to be required for virulence in several human pathogenic bacteria. Rhamnose is known to be a minor cell wall glycan in fungi and has therefore not been suspected as a crucial molecule in fungal-host interactions. Nevertheless, our study shows that deletion of the VdNRS/ER gene from the V. dahliae genome results in complete loss of pathogenicity on tomato and Nicotiana benthamiana plants, whereas vegetative growth and sporulation are not affected. We demonstrate that VdNRS/ER is a functional enzyme in the biosynthesis of uridine diphosphate (UDP)-rhamnose, and further analysis has revealed that VdNRS/ER deletion strains are impaired in the colonization of tomato roots. Collectively, our results demonstrate that rhamnose, although only a minor cell wall component, is essential for the pathogenicity of V. dahliae