Nondestructive Investigation of Stress-Induced Damage in Concrete

The changes in the sonic surface wave velocity of concrete under stress were investigated in this paper. Surface wave velocities at sonic frequency range were measured on a prismatic concrete specimen undergoing several cycles of uniaxial compression. The loading was applied (or removed) gradually in predefined small steps (stress-controlled). The surface wave velocity was measured at every load step during both loading and unloading phases. Acoustic Emission (AE) test was conducted simultaneously to monitor the microcracking activities at different levels of loading. It was found that the sonic surface wave velocity is highly stress dependent and the velocity-stress relationship follows a particular trend. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories, each valid over a certain range of applied stresses. Having measured the velocities while unloading, when the material suffers no further damage, the effect of stress and damage could be differentiated. The slope of the velocity-stress curves over the elastic region was calculated for different load cycles. This quantity was normalized to yield a dimensionless nonlinear parameter. This parameter generally increases with the level of induced damage in concrete

Cadmium, copper and zinc stable isotopes as analytical tool to trace sources and processes in agricultural systems

In agriculture, mineral phosphate (P) fertilizer application leads to an unintended input of Cadmium (Cd) into agricultural systems. Cd is highly toxic and its incorporation into the food chain endangers human health. Copper (Cu) and zinc (Zn) are used as feed additives and pharmaceuticals and can accumulate with farmyard manure in agricultural soils. Although being micronutrients, high Cu and Zn concentrations are toxic. Former studies revealed Cd, Cu and Zn accumulations in Swiss agricultural soils in the past decades. However, these studies were not completely based on in-situ measured data. The aim of this study was to fill this gap and measure Cd, Cu and Zn fluxes at selected Swiss agricultural sites. Specifically, we aimed to trace the metals in the soil and to differentiate between anthropogenic and geogenic sources. Additionally, we further elucidated metal redistribution in Swiss agricultural systems, based on the measurements of stable metal isotope ratios of different system pools. For that purpose, metal balances of three arable (Cd) and three grassland (Cu & Zn) sites were determined by measuring the soil metal concentrations and all inputs (bulk deposition, mineral P fertilizers, manure & parent material) and outputs (seepage water, crop & grass harvest) during one hydrological year (May 2014 – May 2015). Furthermore, stable metal isotopes of the soil and all inputs and outputs were (Cd) and will be (Cu & Zn) determined. Cd mass balances showed losses for wheat cultivation (-0.01 to -0.35 g ha-1 y-1) and accumulations for barley cultivation (0.18 to 0.71 g ha-1 y-1). Isotopic ratios in wheat (∆114/110Cdstraw-grain = -0.34 to -0.38‰) and barley plants (-0.44 to -0.82‰) revealed that uptake and retranslocation of Cd in the plants is driven by physiological processes to reduce toxic Cd impacts. Cu and Zn mass balances showed that manure application is by far the most important Cu (146-340 g ha-1 y-1) and Zn (947-1’742 g ha-1 y-1) input. Inputs with bulk deposition and through parent material weathering were by 1-2 orders of magnitude smaller. Beside the Cu and Zn budgets, stable isotope data (not yet analysed) will be presented and discussed to assess the biogeochemical processes and redistribution of (anthropogenic) Cu and Zn in agricultural systems

Thiosulfate sulfurtransferase prevents hyperglycemic damage to the zebrafish pronephros in an experimental model for diabetes

Thiosulfate sulfurtransferase (TST, EC 2.8.1.1), also known as Rhodanese, was initially discovered as a cyanide detoxification enzyme. However, it was recently also found to be a genetic predictor of resistance to obesity-related type 2 diabetes. Diabetes type 2 is characterized by progressive loss of adequate β-cell insulin secretion and onset of insulin resistance with increased insulin demand, which contributes to the development of hyperglycemia. Diabetic complications have been replicated in adult hyperglycemic zebrafish, including retinopathy, nephropathy, impaired wound healing, metabolic memory, and sensory axonal degeneration. Pancreatic and duodenal homeobox 1 (Pdx1) is a key component in pancreas development and mature beta cell function and survival. Pdx1 knockdown or knockout in zebrafish induces hyperglycemia and is accompanied by organ alterations similar to clinical diabetic retinopathy and diabetic nephropathy. Here we show that pdx1-knockdown zebrafish embryos and larvae survived after incubation with thiosulfate and no obvious morphological alterations were observed. Importantly, incubation with hTST and thiosulfate rescued the hyperglycemic phenotype in pdx1-knockdown zebrafish pronephros. Activation of the mitochondrial TST pathway might be a promising option for therapeutic intervention in diabetes and its organ complications

Microfabrication of a biomimetic arcade-like electrospun scaffold for cartilage tissue engineering applications

Designing and fabricating hierarchical geometries for tissue engineering (TE) applications is the major challenge and also the biggest opportunity of regenerative medicine in recent years, being the in vitro recreation of the arcade-like cartilaginous tissue one of the most critical examples due to the current inefficient standard medical procedures and the lack of fabrication techniques capable of building scaffolds with the required architecture in a cost and time effective way. Taking this into account, we suggest a feasible and accurate methodology that uses a sequential adaptation of an electrospinning-electrospraying set up to construct a system comprising both fibres and sacrificial microparticles. Polycaprolactone (PCL) and polyethylene glycol were respectively used as bulk and sacrificial biomaterials, leading to a bi-layered PCL scaffold which presented not only a depth-dependent fibre orientation similar to natural cartilage, but also mechanical features and porosity compatible with cartilage TE approaches. In fact, cell viability studies confirmed the biocompatibility of the scaffold and its ability to guarantee suitable cell adhesion, proliferation and migration throughout the 3D anisotropic fibrous network. Additionally, likewise the natural anisotropic cartilage, the PCL scaffold was capable of inducing oriented cell-material interactions since the morphology, alignment and density of the chondrocytes changed relatively to the specific topographic cues of each electrospun layer.publishe

Scaffolds for cartilage regeneration: to use or not to use?

Joint cartilage has been a significant focus on the field of tissue engineering and regenerative medicine (TERM) since its inception in the 1980s. Represented by only one cell type, cartilage has been a simple tissue that is thought to be straightforward to deal with. After three decades, engineering cartilage has proven to be anything but easy. With the demographic shift in the distribution of world population towards ageing, it is expected that there is a growing need for more effective options for joint restoration and repair. Despite the increasing understanding of the factors governing cartilage development, there is still a lot to do to bridge the gap from bench to bedside. Dedicated methods to regenerate reliable articular cartilage that would be equivalent to the original tissue are still lacking. The use of cells, scaffolds and signalling factors has always been central to the TERM. However, without denying the importance of cells and signalling factors, the question posed in this chapter is whether the answer would come from the methods to use or not to use scaffold for cartilage TERM. This paper presents some efforts in TERM area and proposes a solution that will transpire from the ongoing attempts to understand certain aspects of cartilage development, degeneration and regeneration. While an ideal formulation for cartilage regeneration has yet to be resolved, it is felt that scaffold is still needed for cartilage TERM for years to come

Postnatale Entwicklung und cancerogene Wirkung bei NMRI-Maeusen nach der Kombinationsbehandlung mit Roentgenstrahlen und Ethylnitrosoharnstoff an verschiedenen Tagen der Fetalperiode

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Postnatale Entwicklung und cancerogene Wirkung bei NMRI-Maeusen nach der Kombinationsbehandlung mit Roentgenstrahlen und Ethylnitrosoharnstoff an verschiedenen Tagen der Fetalperiode

Available from: Zentralstelle fuer Agrardokumentation und -information (ZADI), Villichgasse 17, D-53177 Bonn / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Postnatal development and neoplastic disease pattern in NMRI mice after combined treatment with ethylnitrosourea and X-irradiation on different days of the fetal period.

Mice were X-irradiated on day 14, 15 or 16 of gestation with 1·0 Gy. This did not result in an increased tumour frequency in the offspring until 12 months. Mice treated with ethylnitrosourea (ENU) (45 mg/kg) on these gestation days developed a significantly increased tumour frequency in the lungs and liver, and in the ovaries after treatment on day 15 of gestation. Additionally this experiment was the first to show that ENU treatment on gestation day 14, 15 or 16 results in haemangiosarcomas of the subcutis at a low incidence (2·0, 2·4, 2·6 per cent). After combined treatment with these two agents in the sequence X + ENU and an interval of 4 h, a significantly increased incidence rate of animals with tumours was observed in the offspring treated on gestation day 14 or 16. Moreover, the treatment on gestation day 16 exhibited the highest tumour frequency per examined animal (5·7) of all treatment groups. This result is due to a relatively uniform increase of all tumor types. Within this pattern, the frequency of liver tumours was most marked. The diagnosed liver tumours were significantly augmented after X + ENU treatment on day 16. In the reverse sequence (ENU + X), the total tumour outcome was not significantly altered compared with the effects of ENU alone. However, detailed analysis also showed a significant augmentation of the liver tumour frequency with treatment on day 15

Nondestructive investigation of stressinduced damage

The changes in the sonic surface wave velocity of concrete under stress were investigated in this paper. Surface wave velocities at sonic frequency range were measured on a prismatic concrete specimen undergoing several cycles of uniaxial compression. The loading was applied (or removed) gradually in predefined small steps (stress-controlled). The surface wave velocity was measured at every load step during both loading and unloading phases. Acoustic Emission (AE) test was conducted simultaneously to monitor the microcracking activities at different levels of loading. It was found that the sonic surface wave velocity is highly stress dependent and the velocity-stress relationship follows a particular trend. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories, each valid over a certain range of applied stresses. Having measured the velocities while unloading, when the material suffers no further damage, the effect of stress and damage could be differentiated. The slope of the velocity-stress curves over the elastic region was calculated for different load cycles. This quantity was normalized to yield a dimensionless nonlinear parameter. This parameter generally increases with the level of induced damage in concrete