75,312 research outputs found
Characterization and prediction of cracks in coated materials: direction and length of crack propagation in bimaterials
No full textThe behaviour of materials is governed by the surrounding environment. The contact area between the material and the surrounding environment is the likely spot where different forms of degradation, particularly rust, may be generated. A rust prevention treatment, like bluing, inhibitors, humidity control, coatings, and galvanization, will be necessary. The galvanization process aims to protect the surface of the material by depositing a layer of metallic zinc by either hot-dip galvanizing or electroplating. In the hot-dip galvanizing process, a metallic bond between steel and metallic zinc is obtained by immersing the steel in a zinc bath at a temperature of around 460°C. Although the hot-dip galvanizing procedure is recognized to be one of the most effective techniques to combat corrosion, cracks can arise in the intermetallic layer. These cracks can affect the life of the coated material and decrease the lifetime service of the entire structure. In the present paper the mechanical response of hot-dip galvanized steel submitted to mechanical loading condition is investigated. Experimental tests were performed and corroborative numerical and analytical methods were then applied in order to describe both the mechanical behaviour and the processes of crack/cracks propagation in a bimaterial as zinc-coated material
Numerical simulation in coated materials: model of crack propagation bi-material
No full textFrom the simple device to complex assembly, protection against corrosion is the most important treatment. As well as known, this treatment could be done in different varieties in the function of available resources and depending on economic price. Most of the time, protection is made with the use of one material, that holds the highest anti-corrosion characteristics, through a form of a thin film layer.
Among various materials, zinc may be considered as one. Zinc could be applied under the thin layer during the hot dip galvanized steel process. During this procedure of steel coating, some cracks are initiated in the intermetallic layer δ and spread in the layered surface of the zinc coating. For the simulation of this process we use the finite element method (FEM). The realization of modelling is done in the bi-material steel-zinc model, using the computer software application Abaqus 6.10.1
Anticancer biomaterials: A special design for precision medicine
No full textDespite prominent progress in cancer detection and therapy, critical challenges still remain and need to be addressed. In this sense, several innovative biomaterials have been designed and produced using different types of biocompatible materials like metals, and polymers, as well as glasses and glass-ceramics. Currently, more precise treatments can be achieved based on the tissue type, the stage of the cancer, and other patient-specific factors, resulting in improved cancer diagnosis and treatment. Indeed, the integration of interdisciplinary research areas, including tissue engineering, regenerative medicine, biomaterials science, nanotechnology, and pharmacology has led to a move forward toward cancer precision medicine. In this sense, precision biomaterials have emerged as promising approaches for more efficient modeling, detection, and treatment of cancers. In this chapter, we will discuss the recent advances and potential applications of precision biomaterials for personalized cancer treatment and try to summarize future directions according to the available data in the literature
Spaces of contestation: the everyday experiences of ten African migrants in Cape Town
No full textIncludes bibliographical references.Xenophobia in South Africa is so overt that it has take a covert form. The 'xenocide' events that took place in 2008 were called xenophobic acts. It is the recurrent denialism of xenophobia on an everyday basis that this project has explored through the narrative accounts of ten African migrants in Cape Town. The lived everyday experiences of ten African migrants have brought forward the central argument of this thesis. From the data, it is evident that as a reponse to everyday pressures of prejudices and xenophobia in social and physical spaces, African migrants have developed mutable, unsettled and vagrant identities in order to cope with everyday low level violence. This argument emerged as four key stressors have been identified as the components of a more substantial explanation of xenophobia in South Africa. The four key components are: the enforcement of identity (national and group), the demarcation of spaces of belonging, the experiences of economic insecurity, and lastly a 'culture of violence' in South Africa. This thesis argues that these four stressors are the result of an on-going active process of xenophobic attitudes
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Islamska teokracija šiitskih dvanajstnikov v Iranu
No full textThe paper introduces the concept of Velayat-e faqih (Guardianship of the
Jurist) as actual political system in Iran. The Farsi concept transfers the authority, political
and religious, to the Shia clergy called ruling faqih (ruling jurist). It means that the religious
leader (Vali-e faqih) is in fact the supreme leader in Iran. He gets his authority from God
and he has already been appointed by the Hidden Imam and he would just be discovered
by Maraj-e taghlid. Shia Islam knows a particular meaning of the concept Velayat-e faqih,
started by Islamic Revolution in 1979. The paper presents the interpretation of the doctrine
formulated by the dissident Iranian cleric Ayatollah Ruhollah Khomeini. The presentation
is based on his book Islamic Government: Governance of the Jurist. The paper compares
different views of Velayat-e faqih and it describes the relation of the actual Iranian understanding of Velayat-e faqih with traditional Shia custom and practice. This paper is written
in English but it is based on the Farsi bibliography and is supported by the life experience
of the political system.Članek predstavlja koncept Velayat-e faqih (Pravnikovo skrbništvo) kot trenutno
politično ureditev v Iranu. Perzijski koncept izroča politično in versko oblast šiitskemu duhovniku, ki se imenuje vladajoči faqih (vladajoči pravnik). To pomeni, da je verski voditelj
(Vali-e faqih) v resnici vrhovni voditelj v Iranu. Bog mu je dal avtoriteto in Skriti imam ga je
imenoval, neposredno pa ga je odkril Maraj-e taghlid. Šiitski islam pozna poseben pomen
izraza Velayat-e faqih, ki ga je začela islamska revolucija leta 1979. Prispevek predstavlja
interpretacijo doktrine, ki jo je oblikoval disidentski iranski klerik ajatola Ruholah Homeini.
Članek temelji na njegovi knjigi Islamska vlada: vladanje pravnika, ki je bila prvič natisnjena
leta 1970. Avtorja primerjata različne poglede na Velayat-e faqih in opišeta razmerje sedanjega iranskega razumevanja koncepta s tradicionalnimi šiitskimi običaji in prakso. Članek
je napisan v angleščini, vendar temelji na iranski bibliografiji in je podprt z življenjskimi
izkušnjami političnega sistem
Final word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
Zinc- and Copper-Doped Mesoporous Borate Bioactive Glasses: Promising Additives for Potential Use in Skin Wound Healing Applications
No full textIn this study, zinc (Zn)- and copper (Cu)-doped 13-93B3 borate mesoporous bioactive glasses (MBGs) were successfully synthesized using nitrate precursors in the presence of Pluronic P123. We benefited from computational approaches for predicting and confirming the experimental findings. The changes in the dynamic surface tension (SFT) of simulated body fluid (SBF) were investigated using the Du Noüy ring method to shed light on the mineralization process of hydroxyapatite (HAp) on the glass surface. The obtained MBGs were in a glassy state before incubation in SBF. The formation of an apatite-like layer on the SBF-incubated borate glasses was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The incorporation of Zn and Cu into the basic composition of 13-93B3 glass led to changes in the glass transition temperature (Tg) (773 to 556 °C), particle size (373 to 64 nm), zeta potential (−12 to −26 mV), and specific surface area (SBET) (54 to 123 m2/g). Based on the K-means algorithm and chi-square automatic interaction detection (CHAID) tree, we found that the SFT of SBF is an important factor for the prediction and confirmation of the HAp mineralization process on the glasses. Furthermore, we proposed a simple calculation, based on SFT variation, to quantify the bioactivity of MBGs. The doped and dopant-free borate MBGs could enhance the proliferation of mouse fibroblast L929 cells at a concentration of 0.5 mg/mL. These glasses also induced very low hemolysis (<5%), confirming good compatibility with red blood cells. The results of the antibacterial test revealed that all the samples could significantly decrease the viability of Pseudomonas aeruginosa. In summary, we showed that Cu-/Zn-doped borate MBGs can be fabricated using a cost-effective method and also show promise for wound healing/skin tissue engineering applications, as especially supported by the cell test with fibroblasts, good compatibility with blood, and antibacterial properties
Stem cell-mediated angiogenesis in skin tissue engineering and wound healing
No full textThe timely management of skin wounds has been an unmet clinical need for centuries. While there have been several attempts to accelerate wound healing and reduce the cost of hospitalisation and the healthcare burden, there remains a lack of efficient and effective wound healing approaches. In this regard, stem cell-based therapies have garnered an outstanding position for the treatment of both acute and chronic skin wounds. Stem cells of different origins (e.g., embryo-derived stem cells) have been utilised for managing cutaneous lesions; specifically, mesenchymal stem cells (MSCs) isolated from foetal (umbilical cord) and adult (bone marrow) tissues paved the way to more satisfactory outcomes. Since angiogenesis plays a critical role in all four stages of normal wound healing, recent therapeutic approaches have focused on utilising stem cells for inducing neovascularisation. In fact, stem cells can promote angiogenesis via either differentiation into endothelial lineages or secreting pro-angiogenic exosomes. Furthermore, particular conditions (e.g., hypoxic environments) can be applied in order to boost the pro-angiogenic capability of stem cells before transplantation. For tissue engineering and regenerative medicine applications, stem cells can be combined with specific types of pro-angiogenic biocompatible materials (e.g., bioactive glasses) to enhance the neovascularisation process and subsequently accelerate wound healing. As such, this review article summarises such efforts emphasising the bright future that is conceivable when using pro-angiogenic stem cells for treating acute and chronic skin wounds
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
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