Determination of the Failure Stresses for Fluid-filled Microcapsules that Rupture Near the Elastic Regime

The encapsulation of liquids within an external wall or shell is an important technology often utilized in the production of many commercial products. The mechanical characterization of such microcapsules is paramount in order to fully understand their performance in their target environment. Some microcapsules, with wall materials such as inorganic based compounds, rupture at small deformations, commonly near the elastic regime. The study herein presents a general methodology that enables calculation of the failure stresses leading to the elastic-like rupture of microcapsules under parallel compression testing. Two scenarios of failure, brittle and ductile, were considered. Analyses of the critical stresses present within the microcapsule wall during different degrees of fractional deformation were obtained using finite element modelling, resulting in similar values for both the brittle and ductile scenarios. The correlations presented were used to determine the failure stresses of tetraethoxyorthosilane-methyltrimethoxysilane (TEOS-MTMS) microcapsules with a model core oil, which are 11?C14?±?10?MPa. The data were further analyzed using Weibull distributions.     

N-Cyanoimides via the Cyanation of Imides

The conversion of cyclic imides to the corresponding N-cyanoimides has been carried out using cyanogen bromide as the nitrile source. This methodology provides a convenient route for the preparation of both aromatic and aliphatic N-cyanoimides.     

The Berkeley Center for Structural Biology at the Advanced Light Source

The Berkeley Center for Structural Biology (BCSB) operates and develops a suite of protein crystallography beamlines at the Advanced Light Source (ALS) located at Lawrence Berkeley National Laboratory (LBNL). Although the ALS was conceived as a low-energy (1.9-GeV), third-generation synchrotron source of vacuum ultraviolet (VUV) and soft X-ray radiation, it was realized during the development of the facility in the mid-1990s that a multipole wiggler coupled with brightness-preserving optics would result in a beamline whose performance in the energy range of 5 to 15 keV would be sufficient for most protein crystallographic experiments. Later, the hard X-ray capabilities of the ALS were expanded by the addition of three superconducting bending magnets, resulting in additional protein crystallography facilities at the ALS [1 A.A. MacDowell, J Synchrotron Radiation 11(6), 447–55 (2004).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]].     

[UIII{N(SiMe2tBu)2}3]: A Structurally Authenticated Trigonal Planar Actinide Complex

We report the synthesis and characterization of the uranium(III) triamide complex [U^III(N**)₃] [ 1 , N**=N(SiMe₂tBu)₂^?]. Surprisingly, complex 1 exhibits a trigonal planar geometry in the solid state, which is unprecedented for three‐coordinate actinide complexes that have exclusively adopted trigonal pyramidal geometries to date. The characterization data for [U^III(N**)₃] were compared with the prototypical trigonal pyramidal uranium(III) triamide complex [U^III(N“)₃] (N”=N(SiMe₃)₂^?), and taken together with theoretical calculations it was concluded that pyramidalization results in net stabilization for [U^III(N“)₃], but this can be overcome with very sterically demanding ligands, such as N**. The planarity of 1 leads to favorable magnetic dynamics, which may be considered in the future design of U^III single‐molecule magnets.     

Molecular dynamics in a miscible polyester blend

The dynamic mechanical and dielectric spectra of a miscible polyester and polycarbonate blend are investigated with emphasis on the latter technique. It was found that relaxation spectra for the blends from both techniques are broader than those of the constituent homopolymers. This is ascribed to greater intermolecular coupling and concentration fluctuations within the blends. The composition at which the greatest coupling occurs is dependent on the relaxation technique used and is skewed towards the component which shows the highest degree of intermolecular coupling. A number of parameters, such as relaxation time of the polymer molecules in the blend and relaxation strength, are compared as a function of reduced temperature (experimental temperature scaled by the glass transition temperature). Whereas blend behavior is generally intermediate between that of the homopolymers, it appears as though mobility of compositions with low polyester content have a greater relaxation time and possess a higher activation energy when compared to a simple, weighted average of the corresponding homopolymer values. © 1996 John Wiley & Sons, Inc.     

Adaptive Neuro-Fuzzy Inference System and a Multilayer Perceptron Model Trained with Grey Wolf Optimizer for Predicting Solar Diffuse Fraction

The accurate prediction of the solar diffuse fraction (DF), sometimes called the diffuse ratio, is an important topic for solar energy research. In the present study, the current state of Diffuse irradiance research is discussed and then three robust, machine learning (ML) models are examined using a large dataset (almost eight years) of hourly readings from Almeria, Spain. The ML models used herein, are a hybrid adaptive network-based fuzzy inference system (ANFIS), a single multi-layer perceptron (MLP) and a hybrid multi-layer perceptron grey wolf optimizer (MLP-GWO). These models were evaluated for their predictive precision, using various solar and DF irradiance data, from Spain. The results were then evaluated using frequently used evaluation criteria, the mean absolute error (MAE), mean error (ME) and the root mean square error (RMSE). The results showed that the MLP-GWO model, followed by the ANFIS model, provided a higher performance in both the training and the testing procedures.     

Performance and Modeling of the MWIR HgCdTe Electron Avalanche Photodiode

The operation of the mid-wave infrared (MWIR) HgCdTe cylindrical electron injection avalanche photodiode (e-APD) is described. The measured gain and excess noise factor are related to the collection region fill factor. A two-dimensional diffusion model calculates the time-dependent response and steady-state pixel point spread function for cylindrical diodes, and predicts bandwidths near 1 GHz for small geometries. A 2 μm diameter spot scan system was developed for point spread function and crosstalk measurements at 80 K. An electron diffusion length of 13.4 μm was extracted from spot scan data. Bandwidth data are shown that indicate bandwidths in excess of 300 MHz for small unit cells geometries. Dark current data, at high gain levels, indicate an effective gain normalized dark density count as low as 1000 counts/μs/cm² at an APD gain of 444. A junction doping profile was determined from capacitance–voltage data. Spectral response data shows a gain-independent characteristic.     

High-speed digital signal processing and control

An attempt is made to organize and survey recent work, and to present it in a unified and accessible form. The need for a new approach suitable for high-speed processing is discussed in the context of several applications in control and communications, and a historical perspective of the use of difference operators in numerical analysis is presented. The general systems calculus, based on divided-different operators is introduced to unify the continuous-time and discrete-time systems theories. This calculus is then used as a framework to treat the three problems of system state estimation; system identification and time-series modeling; and control system design. Realization aspects of algorithms based on the difference operator representation, including such issues as coefficient rounding and implementation with standard hardware, are also discussed