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Shape memory ceramics (SMCs) exhibit a number of significant advantages over the more common shape memory metals. Zirconia-based SMCs, for example, can achieve much higher transformation stresses (~GPa) and be [...]

The demand of precise injection-molded parts is steadily increasing and is today one of the most relevant challenges, due to local variations in temperature and pressure during the production of the part. These variations can lead to a significant change of the local specific volume, shrinkage potential, and inner stress, which ultimately results in part warpage. By homogenizing the local specific volume over the part according to the specific pvT-behavior of the polymer, warpage is expected to be reduced. The following work describes a new approach to control the local specific volume by a newly developed segmented and highly dynamic mold temperature control based on rapid heating ceramics and C[O.sub.2] evaporation chambers. Since injection molding is a dynamic process and heat transfer inside the mold is comparably slow, a special control strategy is necessary to activate the heating and cooling elements in advance. For this, a novel prediction strategy based on a discretization of the onedimensional heat equation has been developed. Experimental trials including a classical PID controller and a model predictive control approach (MPC) show that the MPC is superior regarding the process stability. KEYWORDS computer, injection, modeling, molding, polyolefins, 1 | INTRODUCTION Injection molding of plastic parts is greatly advantageous regarding the freedom of design and material selection as well as the efficiency for mass production. Nevertheless, like any [...]

Art nouveau was born around 1880, spread like wildfire, and by 1905 was dying. It was a new art to suit a new age of turbulent politics and rapid mechanisation. [...]

Ordered mesoporous materials have attracted much more attention in the past decades because of their potential for advanced applications in separation technologies, catalysis, electronic engineering and nano-science due to their [...], Magnetic mesoporous silica was used for electrode modification and electro-oxidation of some cardiovascular drugs. The modified electrode was applied for detection of cardiovascular drugs using cyclic voltammetry, chronoamperometry, and differential pulse voltammetry. The modified electrode shows many advantages as an electrochemical sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, high sensitivity, excellent activity, short response time, long term stability and remarkable antifouling property toward for cardiovascular drugs and its oxidation product. Finally, the applicability of the sensor for determination of the selected drugs in human serum samples has been successfully demonstrated. Keywords: silica mesoporous, magnetic nanoparticle, electroceramic, electrochemical sensor, cardiovascular drugs DOI: 10.1134/S106193481602009X

Temperature-sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition [Cu.sub.0.1][Ni.sub.0.1][Co.sub.1.6][Mn.sub.1.2][O.sub.4] (with [p.sup.+]-types of electrical conductivity), [Cu.sub.0.1][Ni.sub.0.8][Co.sub.0.2][Mn.sub.1.9][O.sub.4] (with p-types of electrical conductivity), and their multilayers of [p.sup.+]-p and p-[p.sup.+]-p structures were fabricated and studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170°C. It is shown that degradation processes connected with diffusion of metallic Ag into grain boundaries occur in one-layer p- and [p.sup.+]-conductive thick films. The [p.sup.+]-p structures were of high stability, the relative electrical drift being no more than 1%. Positron trapping processes in so-called 'free' thick-film structures based on spinel-type [Cu.sub.0.1][Ni.sub.0.8] [Co.sub.0.2] [Mn.sub.1.9][O.sub.4] ceramics are studied. It is shown that two-state positron trapping model is appropriate for an adequate description of changes caused by additional glass phase in these materials. The observed behaviour of defect-related component in the fit of the experimentally measured positron lifetime spectra for thick films in comparison with bulk ceramics testifies in favour of agglomeration of free volume entities during technological process. PACS Nos.: 68.65.Ac, 85.40.Xx, 81.05.Mh. Resume : Nous avons fabrique et etudie des films epais et sensibles a la temperature, de semi-conducteurs ceramiques de type spinelle de differentes compositions chimiques : [Cu.sub.0.1][Ni.sub.0.1]Co16Mn1.2[O.sub.4] (avec conductivite electrique de type [p.sup.+]), [Cu.sub.0.1][Ni.sub.0.8] [Co.sub.0.2][Mn.sub.1.9][O.sub.4] (avec conductivite electrique de type p) ainsi que leurs structures multicouches [p.sup.+]-p et p-[p.sup.+]-p. Ces films epais possedent de bonnes caracteristiques electro-physiques avant et apres un processus de vieillissement a 170°C. Nous montrons que la degradation associee a la diffusion de Ag dans les joints de grain apparait dans les films epais a une couche de type [p.sup.+] ou p. Les structures [p.sup.+]-p sont tres stables, la derive electrique ne depassant pas 1 %. Nous etudions le mecanisme de piegeage de positron dans les films epais libres de type ceramique spinelle [Cu.sub.0.1][Ni.sub.0.8][Co.sub.0.2] [Mn.sub.1.9][O.sub.4]. Nous montrons que le modele a deux etats de piegeage de positron est approprie pour une description adequate des changements causes par l'ajout d'une phase verre dans ces materiaux. Le comportement observe de la composante defaut dans le lissage des spectres experimentaux de temps de vie mesures des positrons dans les films epais compares a des ceramiques en volume, suggere l'agglomeration de volumes libres dans le processus de formation. [Traduit par la Redaction], 1. Introduction Ni[Mn.sub.2][O.sub.4]-Cu[Mn.sub.2][O.sub.4]-Mn[Co.sub.2][O.sub.4] manganites with negative temperature coefficient resistance are well known for fabrication of disc-type negative temperature coefficient thermistors by means of conventional ceramic technology [1, 2]. However, applications [...]

The nose cap demonstrator named Nose_2 has been tested for the second time in the plasma wind tunnel (PWT) facility which is part of the sharp hot structure (SHS) technology project, focused on the assessment of the applicability of ultrahigh temperature ceramics (UHTC) to the fabrication of high performance vehicles and SHS for reusable launch vehicles. In this paper the FEM based thermal analyses, carried out for the rebuilding of this PWT test, are presented. Experimental data measured in the PWT have been compared with numerical ones in order to validate the FEM model and to help in interpreting the experimental test itself. The knowledge on the physical phenomenon under investigation has been greatly improved, thanks to the synergy between numerical and experimental activities. In particular, a qualitative study of the modeling of the tip-dome interface has been performed in order to estimate the thermal contact resistance that heat flux encounters in passing through the demonstrator. The correlation between numerical and experimental temperature curves has been found to be satisfactory for both internal and surface temperature distribution, and the FEM model was found reliable in reproducing the thermal behavior of the nose cap. DOI: 10.1061/(ASCE)AS.1943-5525.0000047 CE Database subject headings: Thermal factors; Wind tunnels; Vehicles; Finite element method. Author keywords: UHTC; Thermal analyses; Thermal contact resistance; Hot structures; Rebuilding.

Biomaterials can be endowed with biologically instructive properties by changing basic parameters such as elasticity and surface texture. However, translation from in vitro proof of concept to clinical application is largely missing. Porous calcium phosphate ceramics are used to treat small bone defects but in general do not induce stem cell differentiation, which is essential for regenerating large bone defects. Here, we prepared calcium phosphate ceramics with varying physicochemical and structural characteristics. Microporosity correlated to their propensity to stimulate osteogenic differentiation of stem cells in vitro and bone induction in vivo. Implantation in a large bone defect in sheep unequivocally demonstrated that osteoinductive ceramics are equally efficient in bone repair as autologous bone grafts. Our results provide proof of concept for the clinical application of 'smart' biomaterials. osteoinduction | bone morphogenetic proteins | mesenchymal stromal cells | surface topography | tricalcium phosphate doi/ 10.1073/pnas.1003600107

The reactive ceramics suitable for the rotary-type solar reactor (proposed by Tokyo Institute of Technology, Tokyo) with two-step water-splitting reaction were developed. It is confirmed that [O.sub.2] gas is evolved in the two-step water-splitting reaction with the reactive ceramics vigorously by rapid heating ([alpha]-[O.sub.2]-releasing reaction). The [alpha]-[O.sub.2]-releasing reaction is due to the formation of interstitial defect and the conversion of lattice oxygen into [O.sub.2] gas at a nonequilibrium state. Reactive ceramics (Ni[Fe.sub.2][O.sub.4] and yttria stabilized zirconia (YSZ)-Ni[Fe.sub.2][O.sub.4] solid solution) can absorb solar thermal energy and convert thermal energy into chemical energy under high [O.sub.2] partial pressure atmosphere in the [alpha]-[O.sub.2]-releasing reaction. Repetitive evolutions of [O.sub.2] gas were observed in the two-step water-splitting reaction with YSZ-Fe3O4 solid solution and cerium based metal oxides (Ce[O.sub.2]-NiO, Ce[O.sub.2]-Zr[O.sub.2], and Ce[O.sub.2]-[Ta.sub.2][O.sub.5]) at high [O.sub.2] partial pressure. The Ce[O.sub.2]-[Ta.sub.2][O.sub.5] (Ce : Ta =90: 10) released a large amount of [O.sub.2] gas (3.95 [cm.sup.3]/g) in the [alpha]-[O.sub.2] releasing reaction in the flow of air. [DOI: 10.1115/1.4001180] Keywords: reactive ceramics, concentrated solar heat, hydrogen production, two-step water-splitting process, ceria

Low-temperature cofired ceramics (LTCC) technology is a versatile fabrication technique used to construct microflow systems. It permits the integration of several unitary operations (pretreatment, separation, (bio)chemical reaction, and detection stage) of an analytical process in a modular or monolithic way. Moreover, because of its compatibility with biological material, LTCC is adequate for analytical applications based on enzymatic reactions. Here we present the design, construction, and evaluation of a LTCC microfluidic system that integrates a micro-reactor (internal volume, 24.28 [mu]L) with an immobilized [beta]-galactosidase from Escherichia coli (0.479 activity units) and an optical flow cell to measure the product of the enzymatic reaction. The enzyme was immobilized on a glyoxal-agarose support, maintaining its activity along the time of the study. As a proof of concept, the LTCC-[beta]galactosidase system was tested by measuring the conversion of ortho-nitrophenyl [beta]-D-galactopyranoside, the substrate usually employed for activity determinations. Once packed in a monolithically integrated microcolumn, the miniaturized flow system was characterized, the operational conditions optimized (flow rate and injection volume), and its performance successfully evaluated by determining the [beta]-galactosidase substrate concentration at the millimolar level. 10.1021/ac902267f

Ceramic gas turbine development that started in the 1950s has slowed considerably since most of the large-scale ceramic gas turbine development programs of the 1970s-1990s ended. While component durability still does not meet expectations, the prospect of significant energy savings and emission reductions, potentially achievable with ceramic gas turbines, continues to justify development efforts. Four gas turbine applications have been identified that could be commercially attractive: a small recuperated gas turbine (microturbine) with ~35% electrical efficiency, a recuperated gas turbine for transportation applications with ~40% electrical efficiency with potential applications for efficient small engine cogeneration, a ~40% efficient midsize industrial gas turbine, and a ~63% (combined cycle) efficient utility turbine. Key technologies have been identified to ensure performance and component durability targets can be met over the expected life cycle for these applications. These technologies include a [Si.sub.3][N.sub.4] or SiC with high fracture toughness, durable EBCs for [Si.sub.3][N.sub.4] and SiC, an effective EBC/TBC for SiC/SiC, a durable oxide/oxide ceramic matrix composite (CMC) with thermally insulating coating, and the next generation CMCs with high strength that can be used as structural materials for turbine components for small engines and for rotating components in engines of various sizes. The programs will require integrated partnerships between government, national laboratories, universities, and industry. The overall cost of the proposed development programs is estimated at U.S. $100M over 10 years, i.e., an annual average of U.S. $10M. [DOI: 10.1115/1.3124669]

The advantages and limitations of zirconium oxide substructure crowns and fixed prostheses with relation to porcelain-fused-to-metal restorations are presented.

We report a step toward optoelectronic integration on low-temperature cofired ceramics substrates in the form of fiber alignment U-grooves. The precision of the COx laser machining of green state ceramic for this purpose is investigated. The groove-writing process with a speed of 1 mm/s was carried out in air at room temperature and ambient pressure. The process is to a large extent self-cleaning without any gas jet assist. By analysis of groove profiles after firing of a near-zero shrinkage green tape formulation, it is shown that the cutting accuracy is approximately 2 [micro]m, which is at the fundamental limit set by the particle size (1-5 [micro]m). We demonstrate low-loss butt coupling of < 1 dB for single-mode fibers using the laser written U-grooves. The technique exhibits a potential for fabrication of low-cost fiber ribbon and fiber array connectors. OCIS codes: 140.3390, 140.3470, 220.4000, 220.1140, 060.2390, 060.2430.

In this study, a dual-band lumped-element bandpass filter (DBLEF) is presented, which is implemented in low-temperature co-fired ceramic. The design utilizes the tight component coupling possible in this technology to mimic a much more complex network of lumped components. The filter is unique in that it utilizes only a single set of lumped components to create a dual-passband response. Detailed design equations are presented for the dual-band design, and a DBLEF having passbands at 2.4 and 5.2 GHz is demonstrated, representing the common wireless local area network bands. This paper both introduces a novel approach to lumped-element dual-band filtering, while also demonstrating an effective method of implementing this complex filter in multilayer technology with a very small footprint. Both measured and simulated results verify the approach with the overall size of the filter only 154 x 135 x 22.8 [mil.sup.3] (3.85 x 3.38 x 0.57 m[m.sup.3]). Index Terms--Bandpass filter, dual-band filter, low-temperature co-fired ceramic (LTCC), multilayer substrates, resonators.

Sculptural genius assumes many guises this month. On 18 December, for instance, Christie's, London, offers examples from the remarkable Meissen menagerie of birds and beasties commissioned by Augustus the Strong [...]

Abstract: The machining of hardened steel and other difficult-to-cut materials require high quality and progressive cutting tools to meet the growing requirements for increasing productivity, improving tool life and quality [...]

There is a long history of Plains societies using paint in stylized and representational artwork. This artwork has been well documented by anthropologists as well as art historians. What is less well documented are the materials used in painting by these groups, especially the means of paint storage. This paper discusses the use of ceramic vessels for paint storage by late prehistoric Plains Villagers in south central and western Oklahoma. Attributes of paint cups and lids are documented. The uses of the paint cups and lids as well as their deposition in the archaeological context are also characterized. Closing comments address contradictions between the ceremonial applications of paint on the Plains and the absence of ritual in the archaeological context of the paint cups and lids. Keywords: ceramics, Plains Villagers, painting, cups, lids

The design requirements for the Fault Current Limiter (FCL) model that is being built by ALSTOM Research and Technology Centre is presented. The FCL model is being built based on an inductive design that requires the use of superconducting materials in the form of thick films grown on ceramic substrates. The property and performance issues concerning the scale-up of component sizes for an YBCO-based thick film material that is under consideration is shown.