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OBJECTIVE: Differences in type 2 diabetes phenotype by age are described, but it is not known whether these differences are seen in a more uniformly defined adult population at a common early stage of care. We sought to characterize age-related clinical and metabolic characteristics of adults with type 2 diabetes on metformin monotherapy, prior to treatment intensification. RESEARCH DESIGN AND METHODS: In the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study (GRADE), participants were enrolled who had type 2 diabetes duration

Lithium-ion batteries with solid electrolytes offer safety, higher energy density and higher long-term performance, which are promising alternatives to conventional liquid electrolyte batteries. Lithium aluminum titanium phosphate (LATP) is one potential solid electrolyte candidate due to its high Li-ion conductivity. To evaluate its performance, influences of the experimental factors on the materials design need to be investigated systematically. In this work, a materials design strategy based on machine learning (ML) is employed to design experimental conditions for the synthesis of LATP. In the variation of parameters, we focus on the tolerance against the possible deviations in the concentration of the precursors, as well as the influence of sintering temperature and holding time. Specifically, models built with different design selection strategies are compared based on the training data assembled from previous laboratory experiments. The best one is then chosen to design new experiment parameters, followed by measuring the corresponding properties of the newly synthesized samples. A previously unknown sample with ionic conductivity of 1.09 × 10$^{-3}$ S cm$^{-1}$ is discovered within several iterations. In order to further understand the mechanisms governing the high ionic conductivity of these samples, the resulting phase compositions and crystal structures are studied with X-ray diffraction, while the microstructures of sintered pellets are investigated by scanning electron microscopy. Our studies demonstrate the advantages of applying machine learning in designing experimental conditions by the synthesis of desired materials, which can effectively help researchers to reduce the number of required experiments.

The volume of silica expands by the hydroxyl generation when silica surfaces react with water. These volume strains are proportional to the mass concentration of the hydroxyl. They were measured by Wiederhorn et al. by evaluating the curvature of disks undergoing this reaction on only one side. The obtained bending moments were found to be proportional to square-root of heat-treatment time. In the present considerations we pay particular attention to global bending moments caused by swelling, which, in contrast to local swelling stresses, do not require assumptions about the type of stress distribution. It can be stated that • The bending moments from disk curvature and hydroxyl measurements via the IR-evaluation procedure by Libowitzky and Rossman are in excellent agreement. • Predictions of moments M based on diffusivities and surface water concentrations by Helmich and Rauch also show good agreement with correlation coefficients R$^2$>0.95. Consequently, we can sufficiently write: M$_{predict}$ = M$_{measured}$.

In two previous reports we have dealt with the description of the time dependence of the water content at the surface of silicate glass by mass transfer (SWP 73 and SWP 94). Literature measurements in the range of 200°C100°C. Measurements by Helmich&Rauch serve as a basis. A step change in the mass transfer coefficient is found at 200°C

Solid oxide fuel cells (SOFC) convert chemical energy from hydrogen, methane, or other hydrocarbons directly into electrical energy and heat. Advantages are low noise during operation as well as relatively low pollutant emissions. This makes them interesting for stationary applications, eg combined heat and power plants for domestic use and for mobile applications, when there is a demand for integrating auxiliary power units. The high operating temperatures of about 850°C and the simultaneous presence by both, reducing and oxidizing atmospheres place high demands on the components of a SOFC. Due to these requirements, glass‐ceramics are proposed as sealants between interconnector and electrolyte. They provide lower costs and lower weight than commercially used silver solders. Furthermore, they have the following impressive benefits: The sealants are electrical insulating, chemical stable and by careful materials selection and adapted manufacturing processes, they adhere well on steel and on ceramic substrates. In order to characterize the adhesion of glass‐ceramic sealants on steel and on zirconia substrates, layer‐like composites are fabricated by screen‐printing and subsequent sintering in air. It turns out that the formation of crystalline phases at the interface is crucial for the adhesion behavior.

During surface machining of glass, machining-induced surface cracks are introduced. The result of a contact between a grain of the grinding wheel and the glass surface can be described by a cracklike damage similar to the cracks obtained by hardness indentation tests. In the present report, we study the generation of such cracks and their interaction with residual stresses in the surface region. For three different loadings (pure tension, indentation, surface stresses) we report the relevant stress intensity factors.

Due to the hydroxyl generation, the silica network ahead of crack tips is damaged. The consequence is a damaged crack-tip zone showing a reduced Young’s modulus. The linear-elastic fracture mechanical treatment by application of stress intensity factors becomes doubtful especially for large zones. In this report, we use a description via well-known models of Elastic-Plastic Fracture Mechanics, namely, the models by Irwin and Dugdale. As an application we compared the results with experimental observations on crack profiles from literature. The computed and observed Crack-Tip Opening Displacements (CTOD) were found to be in good agreement.

When water penetrates into silica surfaces near a crack tip, it reacts with the SiO$_{2}$ network and generates hydroxyl $\equiv$SiOH. Due to the hydroxyl generation, silica expands and gives rise for swelling stresses. The consequence is a fracture mechanics shielding stress intensity factor K$_{sh}$

Different methods were applied so far in order to determine subcritical crack growth for silica. Mostly, fracture mechanics standard tests with macro cracks were used for this purpose. In this report, we evaluated the subcritical crack growth curves from interrupted lifetime tests on silica bending specimens containing small natural flaws. The resulting v-K-curve showed crack growth rates down to 10$^{-14}$ m/s indicating a threshold for subcritical crack growth at K$_{th}$$\approxeq$0.31 MPa$\sqrt{m}$ In the plot of v=f(K/K$_{Ic}$) slight material differences could be eliminated and suitable agreement with macro-crack results by Wiederhorn and Bolz [1] on DCB-specimens and Michalske et al. [2] on DCDC-specimens could be stated.

Water reacting with silica causes the generation of hydroxyl SiOH accompanied by a volume or swelling expansion. The principle of LeChatelier ensures that the hydroxyl concentration increases with increasing externally applied stresses. From the analysis in [1,2] it becomes obvious that a) the hydroxyl concentration must depend on the multi-axiality of the applied stresses, and b) that the swelling effect is anisotropic. On the basis of the results in [1,2] it will be shown that under torsion loading the strongest effects on stress-enhanced hydroxyl generation and swelling strains should occur, although this stress state shows a disappearing hydrostatic stress term.

The main advantages of DCDC-specimens are their completely stable crack extension properties and very high path stability due to the strongly negative T-stress term. Unfortunately, problems of DCDC tests can be identified by comparing experimental results that show for different materials (silicon nitride, glass) deviations from the results to be expected by 2-dimensional FE modelling as usual done in literature. Experimental calibrations on silicon nitrides and mixtures of silicon nitride and silicon carbide resulted in modified relations deviating from FE-results in literature. As a possible source for the differences of measurements and 2-D-FE results, we identified the influence of Poisson’s number. This parameter obviously causes deviations between straight-crack assumption in FEmodelling and observable curved crack fronts in the experiments. In order to avoid specimen buckling we also used short specimens of roughly half length. This may slightly affect the stress intensity factors.

The reaction of water with silica is described by the equilibrium constant k. This property depends on temperature and is affected by stresses. The experimental determination of k is in most cases carried out in presence of swelling stresses. Knowledge of the reaction volume $\Delta$$\overline{V}$ allows an elimination of the swelling stresses and the determination of an equilibrium constant for the case of a stress-free material. An analytical expression of k$_{0}$ as a function of temperature, k$_{0}$=f(T), will be suggested.

Cracks terminating at free surfaces are affected by local stresses in the surface region. Under residual compression, the crack front must retard and under residual tensile stresses advance, both compared with the crack contour in the absence of stresses. This effect can be used for an estimation of residual surface stresses in silica generated during the silica/water reaction and caused by volume swelling. A strong shielding stress intensity factor of about -2.5 MPa$\sqrt{m}$ was found for DCDC specimen heat-treated for 192h at 250°C in water. This result is a clear indication for compressive stresses developing in the water diffusion zone at the surface.

The behavior of cracks in glass is discussed contrary for many years. Both purely elastic material behavior as well as plasticity and viscosity were discussed. One of the key results were the crack opening measurements of Bando which were considered for an indication of non-elastic behavior. There are two effects of water, damage by breaking the ring structure due to chemical water reaction and swelling. In this short note, the effect of damage by the water-glass reaction is addressed. In this report we deal with a purely linear attempt by the J-integral.

The effect of water soaking and heat-treatment in saturated water vapour at 250°C for 192 h on the strength of silica glass is studied. Bending strength meaurements in liquid nitrogen showed a clear increase of the inert strength for heat-treated specimens over that of the untreated material. The increase in strength is interpreted as the consequence of water diffusion into exposed surfaces of the test specimen, which results in swelling of the glass and shielding of cracks, present in the surface of the glass. Experimental results are compared with theoretical predictions.

Silica shows the effect of subcritical crack growth in humid environments. Measurements in liquid water show increasing subcritical crack growth velocities when the temperature is increased as was shown by Wiederhorn and Bolz. Since this has been generally found for glasses, this effect is called normal subcritical crack growth. For measurements on silica in water vapour environment the astonishing effect of decreasing crack-growth rate v at an increased temperature was observed for constant partial water pressure in the humid environment. This surprising result observed in v-K experiments by Suratwala and Steele is called anomalous subcritical crack growth behavior. In the present report we consider the effects of reduced water concentration at silica surfaces and volume swelling by hydroxyl generation as the reasons for anomalous subcritical crack growth. From our computation, we can conclude that silica shows normal subcritical crack growth, when it is taken into account that the real physical stress intensity factor K$_{I}$ is used that describes the stresses in the singular crack-tip field, i.e. when v-is plotted vs. K$_{tip}$.

Water introduced in silica reacts with the silica network under hydroxyl generation that causes a volume swelling. This effect has been discussed quantitatively in much detail in [1] for the case of water entrance by a heat treatment procedure. In the present Report we include also data by Shelby [8] obtained by in-situ generation of hydroxyl in gamma-irradiated silica. This procedure resulted in stronger density changes compared with the heat-treated material. Independent of this fact, we can show that the same volume swelling results for both methods. As an application of the results an estimation of the molar volume of hydroxyl is made.