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Coach maturation: understanding the why, what and how has the potential to influence the coaching profession in its own journey of professionalisation. This paper seeks to provide some insight to how experienced coaches understand their own development processes. With a few exceptions, little has been published on coach development and the literature evidences its strong emphasis on client development leaving a vital knowledge gap in coaches’ learning and development. This study aims to address this void by exploring experienced coaches’ experience of their developmental journeys by employing Interpretative Phenomenological Analysis (IPA) as a research methodology. We purposively selected 46 experienced coaches and interviewed 32 using semi-structured interviews. The findings appeared as a series of narratives, nonlinear, and no logical sequence, it could be defined as ‘messy’. The narratives are: Vehicles of Development, Awareness, Letting Go, Ethical Practice and Characteristics of the Becoming of a Coach. These narratives collectively explain how coaches subjectively approach their often-unplanned development. The findings offer a unique research-based contribution to the literature on coach development with implications for coach education.

SYNOPSIS Projects or project-orientated approaches have become a common form of work in nearly all sectors of economies. This has led to concepts such as 'projectified' and 'project orientated' organizations. By defining projectification of a company, industry, or economy as the share of project work in total work, one can reasonably determine the impact that project management, and by default projectification, has had on that company, industry, or economy in terms of staff optimization and allocation. This paper presents the results for such a projectification study of the South African mining industry. This sector has long been a significant contributor to the country's economy from a gross value added (GVA) and employment point of view. Understanding the impact of projectification and the project management way of work on this industry may potentially add significant value to both the mining and project management knowledge areas. We show that although the mining industry is considered by some to operate in archaic ways, the level of projectification has increased over time, and now represents approximately one third of all work conducted. Keywords: rojectification, mining projects, project management, project management office.

Purpose The aim of this study was to assess a new pump's performance and function by using a virtual mock loop (VML) system for device characterization and mapping. Methods We are developing a novel miniaturized left ventricle assist device (LVAD) configured for transapical insertion (Perfusions Solutions Inc., South Euclid, OH). The results of pump testing in the laboratory, such as pressure-flow performance curves, were used for the analysis of its function as an LVAD. The VML system was programmed to mimic various types of heart failure and provide hemodynamic pressure values before and after activation of LVAD. The circulatory conditions of the VML system were systolic heart failure (SHF), diastolic HF (DHF), and both systolic and diastolic HF (BHF). Results Before and after pump activation with SHF condition and with a pump speed of 14000 RPM, aortic pressure (AoP) increased from 71/50 to 99/97 mm Hg, pulmonary artery pressure (PAP) changed from 44/36 to 44/33 mm Hg, mean left atrium pressure (mLAP) decreased from 25 to 18 mm Hg, mean right atrium pressure (mRAP) increased from 7 to 10 mm Hg; with DHF, AoP changed from 116/81 to 129/113 mm Hg, PAP was 45/34 to 45/31 mm Hg, mLAP was 18 to 15 mm Hg, mRAP was 10 to 12 mm Hg; with BHF, AoP was 65/46 to 98/96 mm Hg, PAP was 44/36 to 45/33 mm Hg, mLAP was 26 to 19 mm Hg, mRAP was 7 to 10 mm Hg. (Figure A; pressure-volume curve with BHF, B; pressure curve with BHF without LVAD, 14000 RPM and 16000 RPM of the pump speed) Conclusion Due to the test results from the VML system, the new LVAD for transapical insertion could have the ability enough to ease symptoms of the patients with various types of heart failure based on results from VML system.

Fuzzy logic regulation of flow was investigated in simulation of a model of the Cleveland Clinic Foundation rotodynamic Cardio Pulmonary Bypass blood pump comprised of impeller model #4079 and volute model #4080. A non-linear model of the pump was derived from pump maps obtained from measurements using a custom made pump dynamometer. Pump speed and generated delta pressure were used as inputs to a fuzzy engine in charge of manipulating the pump's speed; the fuzzy controller was capable of maintaining a setpoint of 6±0.5 l/min when presented with pressure disturbances over a range of ±50 mmHg from the baseline of 100 mmHg.

USGEN 10 triticale was compared with maize as a feed grain in a digestibility trial, a milk production trial and a fattening trial. Apparent digestibilities were determined with eight Holstein steers, in two blocks of a balanced cross-over design. The grain component of the four diets contained triticale and maize in the ratios 100:0, 66:34, 34:66 and 0:100, respectively. Digestibility coefficients were unaffected by level of dietary triticale substitution for maize. For the milk production trial eight Holstein cows were also allocated to two blocks of four animals each and fed the four treatment diets in four consecutive periods. Cows received forage consisting of 20% lucerne hay, 15% wheat straw and 65% oat silage (dry matter basis) ad libitum and a concentrate at 0.5 kg kg−1 milk produced. The grain component of the four concentrates was the same as in the digestibility trial. Milk fat percentage and 4% fat corrected milk production per kg concentrate consumed was lower (P < 0.05) on the dietary treatment containing only triticale grain compared to that on the treatments containing different levels of maize grain. For the fattening trial 30 steers were randomly allocated to the five dietary treatments by stratified sampling. The steers received complete diets for 100 days. The grain portion of the five fattening diets consisted of 100% maize, 75% maize: 25% triticale, 50% maize: 50% triticale, 25% maize: 75% triticale and 100% triticale. Steers on the 50% maize: 50% triticale diet tended to perform better than steers on diets containing only maize or triticale grain. Feed conversion ratio (carcass) was better (P < 0.05) for steers on the 50% maize: 50% triticale diet than for steers on the 100% triticale diet.

Effects of increasing concentrations of alfalfa hay fed in diets containing corn silage, whole cottonseed, tallow, and yeast were studied using 36 midlactation Holstein cows in a 3 × 4 factorial arrangement of treatments with three forage and four fat treatments fed as TMR in three 28-d periods. Forages were 1) 50% corn silage, 2) 37.5% corn silage and 12.5% alfalfa hay, and 3) 25% corn silage and 25% alfalfa hay. Fat treatments were 1) control (0% added fat), 2) 2.5% tallow, 3) 2.5% tallow and 12% whole cottonseed, and 4) 12% whole cottonseed. Yeast was imposed across all treatments and fed to half of the cows continuously throughout the experiment. Statistical models including effect of treatment imposed in the previous period indicated no carry-over effects. Production of milk (21.0 vs. 22.8kg/d), fat (666 vs. 809g/d), FCM (19.9 vs. 22.9kg/d), and SCM (19.9 vs. 22.7kg/d) were lower for cows fed whole cottonseed-corn silage diets than for those fed whole cottonseed-alfalfa hay diets. Added tallow increased milk production with all forage treatments but tended to decrease milk fat percentage with corn silage versus alfalfa hay diets. Tendency toward lower DM, OM, NDF, and ADF digestibilities suggested that fats probably had more negative effects on ruminal fermentation when diets were based on corn silage as the only forage. The depression in milk production and fat percentage that was due to cottonseed or tallow inclusion in corn silage diets was overcome by replacing 25 to 50% of the corn silage DM with alfalfa hay. Yeast treatment had no effect on measured parameters.

Thirty-six early to midlactation Holstein cows were used in a 2 × 3 factorial design to determine effect of three concentrations of hydrolyzed feather meal (0, 3, or 6% of dietary DM) at two protein concentrations (14 or 18% of DM) in TMR on DMI, milk production and composition, and nutrient digestibilities. Diets (DM) contained 50% corn silage and 8% soybean hulls and were balanced with corn meal, soybean meal, and hydrolyzed feather meal. The experiment was conducted over three 28-d periods. Yeast (0 or 57 g/d) was fed continuously to half of the cows throughout all three periods. Concentration of feather meal had no effect on DMI and milk fat percentage at either protein concentration. A curvilinear effect of feather meal on milk production showed 3% feather meal to be beneficial at 14% CP but not at 18% CP. Milk protein percentage was affected adversely by feather meal concentration. Treatment with yeast culture decreased DMI (22.0 vs. 22.9 kg/d), but milk and SCM production and milk fat and protein percentages were not affected. Increasing feather meal had a negative linear effect on CP digestibility and a positive linear effect on NDF digestibility. Increasing dietary CP from 14 to 18% increased CP and NDF digestibilities. Yeast culture tended to increase NDF digestibility. Increasing dietary CP caused increases in blood urea N concentrations; increasing feather meal resulted in curvilinear increases in blood urea N. Dietary yeast culture decreased blood urea N.

The stress patterns—two shears and one direct stress—that are maximally coupled to the electric field in piezoelectric ceramics are identified. This is achieved by a simplifying initial choice of coordinate axes in the ceramic's thermodynamic phase space and by a subsequent sequence of elementary coordinate changes—rotations and scale changes; simple physical arguments lead to the new coordinates. The utility of this perspective is pointed out in two important applications of piezoceramics in acoustic transducers: naval hydrophone sensors and pulse-echo ultrasonic transducers used in medical diagnostic imaging.

By using a new calcium-modified lead titanate ceramic with a near-zero planar coupling coefficient, a series of 1-3 piezocomposite samples was fabricated with a dice-and-fill technique. The ceramic rods were approximately 0.10 mm in size, and the percent of ceramic loading varied from 10 to 30%. Two epoxy resins with different glass transition temperatures and moduli were used. The dielectric properties and the piezoelectric dh and gh coefficients of the composites were measured as a function of pressure and temperature and were found to exhibit little variation, but 10-25% lower than theoretical predictions. A prototype hydrophone made from one of the piezocomposite samples was tested to show a constant free-field voltage sensitivity of -201 dB re V/μPa from 100 Hz to 6 kHz.

A simple physical model of 1-3 composite piezoelectrics is advanced for the material properties that are relevant to thickness-mode oscillations. This model is valid when the lateral spatial scale of the composite is sufficiently fine that the composite can be treated as an effective homogeneous medium. Expressions for the composite's material parameters in terms of the volume fraction of piezoelectric ceramic and the properties of the constituent piezoelectric ceramic and passive polymer are derived. A number of examples illustrate the implications of using piezocomposites in medical ultrasonic imaging transducers. While most material properties of the composite roughly interpolate between their values for pure polymer and pure ceramic, the composite's thickness-mode electromechanical coupling can exceed that of the component ceramic. This enhanced electromechanical coupling stems from partially freeing the lateral clamping of the ceramic in the composite structure. Their higher coupling and lower acoustic impedance recommend composites for medical ultrasonic imaging transducers. The model also reveals that the composite's material properties cannot be optimized simultaneously; tradeoffs must be made. Of most significance is the tradeoff between the desired lower acoustic impedance and the undesired smaller electromechanical coupling that occurs as the volume fraction of piezoceramic is reduced. >

The potential for using first principles calculations for ferroelectrics is delineated. Significant insights into the microscopic origins of ferroelectricity are expected. In terms of practical mat...

After briefly reviewing the state of the art in phonocardiography, this report describes the design and preliminary evaluation of a software-based medical instrument for spectrographic heart sound monitoring. The system uses an ordinary personal computer, an audio amplifier, and an electret microphone that attaches to a precordial stethoscope. In a preliminary clinical evaluation involving 5 subjects, heart sound spectra were easily obtained. We suggest that color spectrographic analysis of the phonocardiogram may become a future noninvasive cardiac monitoring technology.

We propose a model for rational multiagent reorganizations. Borrowing from organization theory, this approach models organizational structure by its natural dimensions (e.g. stratification, diversification, preservation, distribution). Agents choose reorganizations that maximize expected utility by quantifying the value of increasing or decreasing the organization's structure along its dimensions. Thus reorganization control is reduced explicitly to a search in n-dimensional space characterizing organizational structure. Utility of reorganizations is modeled using decision networks. Local and organization-wide measurements provide sufficient data to choose changes that benefit local and global goals. The first phase of evaluation has focused on scalability with promising results. The second phase involves testing the rationality of the reorganization control.

Combining a piezoelectric ceramic and a passive polymer to form a piezocomposite allows the transducer engineer to design new piezoelectrics that offer substantial advantages over the conventional piezoelectric ceramics and polymers. The rod composite geometry provides materials with enhanced electromechanical coupling and with acoustic impedance close to that of tissue; these factors yield transducers for medical ultrasonic imaging with high sensitivity and compact impulse response. The dice-and-fill technique produces piezocomposites that can be readily formed into complex shapes to facilitate focusing the ultrasonic beam. Proper design of the rod spacing yields materials that exhibit low crosstalk between array elements formed by patterning the electrode alone, without cutting between the elements. In this way, curved annular arrays have been made that provide high-quality clinical images of substantial diagnostic value to physicians. Included is an extensive bibliography of papers documenting the role of piezocomposites in ultrasonic imaging transducers. >

The attenuation slope with frequency from the frequency decrease along the ultrasonic echo signal is evaluated in tissue. When the local frequency from the reflected waveform is evaluated, many data segments yield unreliable values because of interference between overlapping echo pulses. The authors advance an analysis based on the singular-value decomposition (SVD) of the Wigner distribution of the signal, which provides a criterion to filter out data segments corrupted by interference. When applied to clinical data, this SVD-Wigner filtering process reduces the scatter in the local frequency estimate sufficiently to produce a reliable estimate of the frequency slope along the signal with about one third of the data needed by conventional short-time Fourier techniques. The improvement is not larger because these clinical data were taken on a scanner with a large sample volume, so that most data segments are perturbed by interference artifacts. Simulations show that in a more tightly focused system, with fewer scatterers contributing to the echoes, the reduction in required data can be appreciable. >

Research is described regarding the use of Petri net theory to analyze selected, well-known software safety case studies. The analysis focused on the n-connectedness characteristics of the Petri nets. Interpretation of the analysis results produced the following conclusions: (1) all of the Petri nets had instances of 1-connectedness at the point depicting where the software failures occurred; and (2) instances of 1-connectedness similar to those described indicate situations where the software should implement some type of exception-handling capability. >

The authors report a transducer structure that combines two orthogonal phase arrays that enable the real-time scanning of two orthogonal sectors. This biplane phased array is formed by partially dicing the opposite faces of a composite piezoelectric plate in orthogonal directions. Individual elements of the orthogonal arrays show broad radiation patterns close to the theoretical expectations for isolated elements. Arrays formed by patterning the electrode alone, without cross dicing, show a narrower directivity pattern for a single element. This narrowing is a refractive effect due to the relatively high acoustic velocities in the composite material as compared with the sound velocity in the propagation medium. It is noted that the concept of the biplane phased array forms the basis for a new class of transducer systems that combine two transducer arrays in a single piezocomposite plate. >

Although modified lead-titanate ceramics exhibit a negligible d/sub 31/ piezoelectric coefficient, piezoelectric-rod/polymer-matrix composites made from them exhibit a substantial d/sub 31/. A theoretical analysis shows that the composite's enhanced d/sub 31/ coefficient arises from lateral stress on the polymer phase being transferred to a longitudinal stress along the ceramic rods by the Poisson effect in the polymer, thus producing a charge through the ceramic's d/sub 33/. For hydrophone applications, this enhanced d/sub 31/ suppresses the hydrostatic response so that the composite's hydrophone figure of merit, d/sub h/g/sub h/, is less than that of the constituent ceramic. Nevertheless, the composite's still substantial d/sub h/g/sub h/, high g/sub h/ coefficient, remarkable pressure stability, low density, formability, and availability in thick sheets provide advantages for naval applications. In ultrasonic transducer applications, the composite structure provides no enhancement in electromechanical coupling, since the modified lead-titanate's k/sub 33/ is nearly the same as its k/sub t/. These expectations are in good agreement with measurements on 1-3 modified lead-titanate/polymer composites made by the dice-and-fill technique. >

The case of a piezoelectric material with infinity m axial symmetry (applicable to piezoceramics and most piezocomposites) is analyzed, and formulae for the resulting structures are derived. In terms of transducer design, the constraints on the elastic and dielectric constants provide no blockage to achieving acoustic impedance matching to the medium and electric impedance matching to the electronics. Electromechanical coupling is shown to be limited by the material's maximal coupling factors. A simple formula is derived which facilitates evaluating the maximal electromechanical coupling factor when the electric field is applied along the polar axis from the planar coupling factor and the thickness coupling factor, which can be readily evaluated from the lateral and thickness resonances of a disk. >

The invention of methods to make new materials with an engineered microstructure that yields a negative Poisson ratio opens a new avenue to optimize the performance of piezoelectric-rod/polymer-matrix composites. Such negative Poisson's ratio materials can be used as the passive phase in the composite to redirect the external stress acting on the piezocomposite so that the resulting stress bearing on the piezoceramic rods produces a maximal piezoelectric response. To project the properties of such a piezocomposite, a simple physical model that assumes constant strain along the rods and constant stress in the perpendicular plane is used. Interesting opportunities to improve the performance of devices made from 1-3 piezocomposites are seen in results calculated for the thickness-mode electromechanical coupling constant relevant to pulse-echo ultrasonic applications and for the hydrostatic electromechanical coupling constant relevant to passive hydrophones. >

A simple physical model of rod composite piezoelectrics is extended to the case where both the polymer matrix and the ceramic rods are piezoelectric. This model incorporates the physical picture that strains and electric field are equal in both materials along the direction of the rods, while the stresses are equal in the plane perpendicular to the rods. If one switches to a coordinate system in which strain and electric field along the rods and the stresses in the perpendicular plane are the independent coordinates, the material properties of the composite are a simple volume fraction weighted average over the constituents' properties. The hydrophone figure of merit is presented for a PZT5-rod/PVDF-matrix composite. The bulk of the piezoelectric response is provided by the piezoceramic; the anisotropic elastic properties of PVDF make it particularly suitable for the composite; and the fact that the piezoelectric constants of PZT and PVDF differ in sign would cause the two phases to act against each other if they were poled by the same bias field. >

In whole-cell studies, two alkynes, 1-pentyne and phenylacetylene, were selective, irreversible inhibitors of monooxygenase enzymes in catabolic pathways that permit growth of bacteria on toluene. 1-Pentyne selectively inhibited growth of Burkholderia cepacia G4 (toluene 2-monooxygenase [T2MO] pathway) and B. pickettii PKO1 (toluene 3-monooxygenase [T3MO] pathway) on toluene, but did not inhibit growth of bacteria expressing other pathways. In further studies with strain G4, chromogenic transformation of alpha,alpha,alpha-Trifluoro-m-cresol (TFC) was irreversibly inhibited by 1-pentyne, but the presence of phenol prevented this inhibition. Transformation of catechol by G4 was unaffected by 1-pentyne. With respect to the various pathways and bacteria tested, phenylacetylene selectively inhibited growth of Pseudomonas mendocina KR1 (toluene 4-monooxygenase [T4MO] pathway) on toluene, but not on p-cresol. An Escherichia coli transformant expressing T4MO transformed indole or naphthalene in chromogenic reactions, but not after exposure to phenylacetylene. The naphthalene reaction remained diminished in phenylacetylene-treated cells relative to untreated cells after phenylacetylene was removed, indicating irreversible inhibition.These techniques were used to differentiate toluene-degrading isolates from an aquifer. Based on data generated with these indicators and inhibitors, along with results from Biolog analysis for sole carbon source oxidation, the groundwater isolates were assigned to eight separate groups, some of which apparently differ in their mode of toluene catabolism.

This overview describes the application of composite piezoelectric materials in acoustical imaging transducers. Attention is focused on one composite structure which has found particularly fruitful applications in acoustical imaging—the 1–3 piezocomposite structure consisting of long thin piezoceramic rods held parallel to each other by a polymer matrix. These piezocomposites may be viewed as ‘new’ materials with a set of ‘effective’ homogeneous materials properties whenever the spatial scale of the constituents in the composite structure is smaller than the wavelength of sound. From knowledge of the sub-wavelength ‘microstructure,’ we obtain an intuitive understanding of the origin of the piezocomposite’s properties, and see how the material properties can be tuned to specific transducer application needs. Commercial applications in medical ultrasonic diagnostics, non-destructive testing, and undersea imaging illustrate the practical exploitation of 1-3 piezocomposites.

A simple physical model of 1-3 composite piezoelectrics that was advanced for the material properties relevant to thickness-mode oscillations is extended to address the hydrostatic response. The model is valid when the lateral spatial scale of the composite is sufficiently fine that the composite can be treated as an effective homogeneous medium. Expressions are derived for the composite's material parameters in terms of the volume fraction of piezoelectric ceramic and the properties of the constituent piezoelectric ceramic and passive polymer. The results are similar to those derived by Haun and Newnham (1983, 1986) using a parallel-series connectivity model. The model is illustrated by analyzing composites made from conventional PZT5 and anisotropic modified lead titanate piezoelectric ceramics. For PZT5, the composite structure enhances its hydrostatic charge coefficient, hydrostatic voltage coefficient, hydrophone figure of merit, and hydrostatic coupling coefficient, while three of these quantities fall short of their pure ceramic values in the modified lead titanate composites. The shortfall is due to an enhanced composite that arises from lateral stress on the polymer being transferred to a longitudinal stress along the ceramic rods by the Poisson effect in the polymer, thus producing a charge through the ceramic's d/sub 33/. >

Piezoelectric materials lie at the heart of ultrasonic transducers. These materials convert electrical energy into mechanical form when generating an interrogating acoustic pulse and convert mechanical energy into an electric signal when detecting its echoes. This paper first surveys the piezoelectric materials in current use: piezoceramics, such as barium titanate, lead zirconate titanate, and modified lead titanate; piezopolymers, such as polyvinylidene difluoride and its copolymer with trifluroethylene; and piezocomposites, consisting of piezoceramic rods in a passive polymer matrix. Each material system has properties which commend them for use in the present single element transducers, annular arrays, sequenced linear arrays, and steered phased arrays. Looking to the future, new transducer possibilities are opening up due to recent piezoelectric material developments, such as, for example, synthesis techniques for fine-grained high-density piezoceramics, electrostrictive relaxor ferroelectric ceramics, novel piezoceramic forming methods, piezoceramic fiber synthesis, piezoceramic/metal multilayer structures, composite acoustoelectric materials, ferroelectric thin film growth and processing, and new piezopolymers. These innovations lead to fabrication of conventional transducers at high frequencies, fine-scale piezocomposites, 11/2-D and 2-D arrays, small intravascular transducers, as well as provide opportunities for new ultrasonic imaging techniques, using pitch-catch and non-resonant traveling wave transducers.

Measurements of the temperature dependence of the heat capacity in LiNH4SO4, Gd2(MoO4)3, Tb2(MoO4)3 and Ni3B7O13Br, near their ferroelectric phase transitions, exhibit multiple peaking. An explanation of this behavior based on strains induced during crystal growth and/or sample fabrication is offered.

Diversity of scholarly opinion is nowhere better illustrated than by the range of views concerning the authorship of A Lover's Complaint. Malone found it a "beautiful poem, in every part of which the hand of Shakespeare is visible". In contrast, Sir Sidney Lee considered that "If...it be by Shakespeare, it must have been written in very early days:' Amplifying this point of view, C. Knox Pooler (1918, p. xxxix) added emphasis by noting that "if the style of A Lover's Complaint is that of Shakespeare's youth, it must have changed for the better before he wrote Venus and Adonis." An important study of the poem was conducted by Mackail (1912) who pointed to the use of several words which do not appear elsewhere in Shakespeare's works. When taken in conjunction with a "cramped, gritty, discontinuous quality" of its overall effect, Mackail felt that he had advanced strong arguments against Shakespeare's authorship. Robertson (1917), extending Mackail's approach, attributed A Lover's Complaint to Chapman, while John Dover Wilson regarded it as a parody by Shakespeare of Chapman. Moreover, Robertson asserted that "to Shakespeare's fame it contributed nothing;, and only the comparative unimportance of the problem kept it undiscussed:' Indeed, until recently little further attention has been devoted to the question of its authorship. Within the last twenty years, the problem has aroused new interest: Jackson (1965), Muir (1964) and Slater (1973, 1975), for example, have investigated again the rare words in the poem and have returned to the view that it is by Shakespeare. Yet

The measured temperature dependence of the dielectric constant and pyroelectric coefficient in FeI, CuC1 and MnI boracites are analyzed according to the thermodynamic model advanced by Dvorak and Petzelt and by Gufan and Sakhnenko for the ferroelectric cubic-orthorhombic phase transition. A simplified form of their thermodynamic potential yields acceptable fits to the data over a large temperature interval. The values of the parameters obtained from the fits, however, are not consistent with the usual systematic neglect of high-order terms in the potential.

A direct method is described for measuring the figures of merit which characterize the performance of pyroelectric materials as infrared vidicon targets or point detectors. The results of experiments carried out as a function of temperature on a proper ferroelectric, triglycine sulfate, and an improper ferroelectric, terbium molybdate, are compared with the predictions of the appropriate thermodynamic theories. It is shown that within the family of rare‐earth molybdates isomorphic to terbium molybdate there exists an optimum value for the figure of merit relevant to pyroelectric vidicon performance.

The isobaric molar heat capacity of CrCl, FeI, CuCl, NiBr and ZnBr boracite at the ferroelectric 4 3m-mm2 phase transition is reported. The magnitude of the rise in Cp at the transition, and the large upper bound values of ΔH and ΔS prove that the phase transition is first order. The values of ΔH follow the trend ZnBr ⪢ NiBr > CrCl ⪢ CuCl > FeI reflecting possible structural dissimilarities amongst the boracites. Thermal annealing of single crystal boracite samples of NiBr and CrCl is found to remove multiple peaking of the heat capacity at the transition resulting in single peak heat capacity curves. The multiple peaking is thought to arise from internal stresses within the crystal.

A study of the effects of deuterium substitution in l (+)-glutamic acid hydrochloride is described. Solid state vibrational spectra depicting band shifts resulting from deuterium indicate that interatomic bond distances remain virtually unchanged. The cell volume expands only 0.05% upon deuteration, while the macroscopic linear and nonlinear polarizabilities are unaffected. The optical nonlinearity is therefore ascribed to the electronic nature of the hydrogen bonds.

1–3 piezoelectric-rod/passive-matrix composites offer advantages over the conventional piezoceramics and piezopolymers for the pulse-echo transducers used in medical ultrasonic imaging. Their benefits include high electromechanical coupling, acoustic impedance close to that of tissue, a wide range of dielectric constants, low dielectric and mechanical losses, an adjustable sound speed, low coupling to spurious oscillations, ease of subdividing into acoustically isolated array elements, and formability into complex curved shapes. Not all benefits are achieved simultaneously. In designing a material for a specific application, the material engineer can choose the piezoceramic, the passive matrix, their relative proportions and the spatial scale of the composite. We delineate the trade-offs in designing piezocomposites which enhance the performance of present ultrasonic transducers as well as make new transducer designs feasible.

In a previous paper we reported a mass spectrometer search for heavy hydrogen-like atoms in an enriched D2O sample produced by the electrolysis of 6×103l commercial D2O, the latter manufactured from 1.2×108l natural water. This set a limit X/H (anomalous/natural hydrogen) ∼10−21−10−22 for the mass range 6 to 350 proton masses. In this paper we report new concentration limits for the same D2O sample, obtained with a spectrometer system designed specifically for the detection of new charged particles of unknown mass. The spectrometer utilises energy loss and time-of-flight techniques to distinguish low-Z heavy particles from normal atomic and molecular ions and covers the mass range 12 to 1200 proton masses. No abnormal events were observed in over 60 hours running (16 μl enriched D2O) from which we infer concentration limits X/D ∼ 10−16−10−17 in the sample and X/H ∼ 10−28 to 10−29 in terrestrial water for most of the above mass range. The possible use of the time-of-flight system for other particle searches, for example anomalous nuclei of fractionally charged quarks, is discussed briefly.

Large single crystals of Ca2Pb(C2H5CO2)6 and Ca2Sr(C2H5CO2)6 have been grown by the solution-growth technique. Dielectric and pyroelectric properties of these salts have been measured for as-grown and annealed samples. The results are analyzed in light of a free energy model appropriate to a second-order pseudo-proper ferroelectric.

Large pyroelectric coefficient (1.2 × 104 μC/m2°C at T − Tc ≃ 2°C) in single crystals of SbSI were measured over a temperature range encompassing the ferroelectric phase transition. Simultaneous measurement of the pyroelectric and dielectric constants-were made and the pyroelectric figure of merit p/K was evaluated at various temperatures.

PZT-Spurrs composites fabricated by the replamine technique improves the pyroelectric figure of merit p/e by a factor of 7 over that of solid PZT. The temperature dependence of the pyroelectric response exhibits an interesting compensation point where the primary and secondary effects cancel out. At room temperature the hard plastic mechanically clamps the PZT, but at higher temperatures the plastic softens. PZT-soft polymer composites showed no enhancement of the pyroelectric figure of merit. Major changes in the pyroelectric response were noted when the sample thickness was comparable to the scale of the composite heterogeneity.

Measurements of the thermal and dielectric properties of single crystals of the double sulfates LiKSO 4 and LiCsSO 4 are reported. Uncertainty in the determination of the space group of LiCsSO 4 is resolved on the basis of optical second harmonic generation and pyroelectric measurements; the correct space group is Pcmn . Measurements of the pyroelectric coefficient, dielectric constant, and specific heat of LiKSO 4 permit an assessment of the suitability of this material for use in pyroelectric detectors.

A considerable increase in the pyroelectric voltage responsivity of TGS can be obtained by slicing the crystal at an oblique angle to the pyroelectric axis. When approaching the transition temperature, both the maximum gain and the angle between the optimum orientation and the pyroelectric axis increase as the dielectric anisotropy increases. The maximum voltage responsivity attainable in oblique cuts is about twice that obtained in a regular cut lying perpendicular to the pyroelectric axis.

The absence of dielectric divergence in improper ferroelectrics makes it possible to obtain a high pyroelectric figure of merit near their transition temperature. Results of measurements carried out as a function of temperature on representatives of three classes of improper ferroelectrics: rare-earth molybdates, propionates, and boracites, show that in each of these the figure of merit rises to a peak value which is superior to that of triglycine sulfate. Analysis of the experimental results using a Landau type free-energy model yields an estimate of the optimum figure of merit obtainable.

Measurements of optical second harmonic generation, specific heat, dielectric constant, and pyroelectric coefficient of LiNH4SO4 and its deuterated analog are reported over a temperature range which includes the two phase transitions near 283 K and 459 K. The results indicate that these materials are potentially useful as pyroelectric detectors. Pyroelectric and second harmonic generation data show that the phase below ∼ 283 K is polar.

An analysis of pyroelectric figures of merit in oblique cuts of crystals belonging to the symmetry class m is presented. It is shown that the optimum cut and the gain depend on the dielectric anisotropy and the orientation of the pyroelectric axis with respect to the dielectric principal axes. Remarkable enhancements are possible in optimum cuts of crystals with large anisotropy ratio in the mirror plane and large deviation of the pyroelectric axis from the principal axes of the dielectric tensor.

The adaptability of 1–3 PZT-rod/polymer-matrix piezoelectric composites commends them for the requirements of medical ultrasonic imaging transducers. We describe material fabrication techniques, material design considerations, and transducer design trade-offs involved in this application. A simple dice-and-fill fabrication technique yields material suitable for transducers with frequencies approaching 10 MHz. The piezocomposites provide high electromechanical coupling and low acoustic impedance – properties superior to those of the conventional piezoceramics and piezopolymers. Composite piezoelectric plates can be formed into complex shapes for beam focusing and steering. Moreover, arrays defined by simply patterning the electrode – not cutting the plate – exhibit no spurious modes in individual elements and low cross-talk between array elements. The resulting device performance is illustrated with a concave annular array which shows high sensitivity (8 dB insertion loss), large bandwidth (57%), ...

Photographs were taken of the visible events occurring around the instant collapse of voltage between 1 mm diameter tungsten electrodes separated by a distance of about 150 μm in high vacuum (1 μtorr). The photographs were taken at 5 ns increments using a Kerr cell shutter switched by the collapse of voltage across the electrodes, combined with an image intensifier camera and a variable length optical path. The photographs show that two distinct light emission patterns were observed, depending on the rate of rise of the applied voltage. These results are consistent with theoretical studies of the mechanism in which field emission from a cathode protrusion causes either the vaporization of an anode spot or the vaporization of the point itself, depending on the rate at which the electric stress is applied.

The continuous cathode crossed-field amplifier, a device characterized by high eificiency and low phase pushing, is considered in terms of wave theory. Based on analytical treatments that have appeared in the literature, a plasma propagation constant is postulated and correlated with observed experimental results. From this, a qualitative concept of mode coupling is dxawn which has proven to be of great value in understanding crossed-field devices and in predicting the characteristics of newly designed tubes. Following a brief section devoted to the crossed-field diode, the experimental observations which led to the theory are presented, culminating in a coupling-of-modes picture of the interaction which is similar to the familiar beam tube treatment. Relationships necessary for checking the theory are given and attention is paid to several important observations affecting design.