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Fat, sugar, theobromine, and caffeine are important compounds in chocolates that influence the physico-chemical and sensory characteristics of the products. These parameters commonly are determined with conventional, time-consuming, environmentally pollutant methods. In this study, near infrared spectroscopy (NIRS) coupled with partial least square regression (PLSR) was used to predict the quantity of these compounds. Fat-free cocoa content was calculated based on the alkaloid concentration, while measured fat content was also used for the cocoa content. Prediction models have also been developed for these parameters. The determination coefficient (R 2 ) of the models were as follows: R 2 cv fat 0.98, theobromine 0.94, caffeine 0.76, sucrose 0.92, cocoa 0.98. The root mean square error (RMSE) was found to be relatively low compared to the determined values (RMSECV fat 1.08 %, theobromine 0.42 mg/g, caffeine 0.1 mg/g, sucrose 3.42 %, cocoa content 1.93 %). Therefore, NIRS can be suitable for the analysis of the quality of dark chocolate., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Marietta Fodor reports administrative support and statistical analysis were provided by Hungarian University of Agriculture and Life Sciences. Marietta Fodor reports a relationship with Hungarian University of Agriculture and Life Sciences that includes: employment. Marietta Fodor has patent - licensed to -. - If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Founding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The FT-NIR technique was used for rapid and non-destructive determination of plum ripeness. The dry matter (DM), titratable acidity (TA), total soluble solids (TSS) and calculated maturity index (MI: TSS/TA) were used as reference values. The PLS correlations were validated via five-fold cross-validation (RMSECV for different parameters: DM: 0.66%, w / w ; TA = 0.07%, w / w ; TSS = 0.72%, w / w ; MI = 1.39) and test set validation (RMSEP for different parameters: DM: 0.65%, w / w TA = 0.07%, w / w ; TSS = 0.61%, w / w ; MI = 1.50). Different classification algorithms were performed for TA, TSS and MI. Linear, quadratic and Mahalanobis discriminant analysis (LDA, QDA, MDA) were found to be the best sample detection methods. The accuracy of the classification methods was 100% for all investigated parameters and cultivars.

Multilayer piezoelectric transducers and resonators are widely used for generating propagating and standing acoustic waves as well as for sensor devices. More recently, layered piezoelectric structures based on thin film technology became increasingly important for electromechanical filters used in mobile phones. As a consequence, analytical mathematical modeling of such structures is of high interest. In this paper, a general rigorous transfer matrix description for one-dimensional (1D) layered structures consisting of piezoelectric, visco-elastic, and dielectric layers of arbitrary number is introduced to characterize the electrical and mechanical behavior of a general piezoelectric transducer or resonator with two electrodes and arbitrary acoustic termination impedances (Rig-1D-model). This model is the most general 1D analytical description of layered piezoelectric structures available and can be used for the characterization of various composite transducer and resonant sensor applications. Considered in detail are layered structures with the technically important cases of only one electromechanically coupled mode, and the structure at one or both outer surfaces is in contact with semi-infinite media. For such devices, it is shown how the frequency dependence of the total electrical admittance and spatial dependence of the displacements can be calculated.

Gestation and the neonatal period are crucial periods in infant development. Many components of breast milk, including fatty acids, play an important role in strengthening the immune system. The aim of our research was to evaluate the fatty acid profiles of milk from 69 mothers, including subjects having a normal weight, obesity, or gestational diabetes. For the analyses, we used gas chromatography (GC) with flame ionization detection (FID) and GC coupled with mass spectrometry (GC/MS). The main fatty acids found in breast milk were palmitic acid (C16:0; 26-28%), linoleic acid (C18:2; 23-28%), and α-linolenic acid linoleic acid (C18:3; 15-17%), followed by myristic acid (C14:0; 5-8%), lauric acid (C12:0; 4-6%) and stearic acid (C18:0; 4-5%). The average breakdown of fatty acids was 50% saturated, 44% polyunsaturated, and 6% monounsaturated. Breast milk samples were classified using principal component analysis and linear discriminant analysis. Results showed that milk from the two major groups of obese and normal body mass index (BMI) could be distinguished with an accuracy of 89.66%. Breast milk samples of Hungarian and Ukrainian mothers showed significant differences based on the fatty acid composition, which variations are attributable to the mothers' dietary habits.

Insects are gaining more and more space in food and feed sectors, creating an intense scientific interest towards insects as food ingredients. Several papers deal with cereal-based products complemented by insect powder in the past few years. However, adulteration and quality control of such products present some hot topics for researchers, e.g. , how can we justify the amounts and/or species of the insects used in the given products? Our paper aims to answer such questions by analysing seven edible insect powders of different species independently. The mixtures with wheat flour were analysed using near infrared spectroscopy and chemometric methods. Not only powders of different species were clearly differentiated, but also mixtures created by different amounts of wheat flour. Prediction of insect content showed 0.65% cross-validated error. The proposed methodology gives an excellent tool for quality control of insect-based cereal food products., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Cyclodextrins are cyclic oligosaccharides that are able to form water-soluble inclusion complexes with small molecules. Because of their complexing ability, they are widely applied in food, pharmaceutical and chemical industries. In this paper we describe the development of a free web-service, Cyclodextrin KnowledgeBase: ( http://www.cyclodextrin.net ). The database contains four modules: the Publication, Interaction, Chirality and Analysis Modules. In the Publication Module, almost 50,000 publication details are collected that can be retrieved by text search. In the Interaction and Chirality Modules relevant literature data on cyclodextrin complexation and chiral recognition are collected that can be retrieved by both text and structural searches. Moreover, in the Analysis Module, the geometries of small molecule-cyclodextrin complexes can be predicted using molecular docking tools in order to explore the structures and interaction energies of the inclusion complexes. Complex geometry prediction is made possible by the built-in database of 95 cyclodextrin derivatives, where the 3D structures as well as the partial charges are calculated and stored for further utilization. The use of the database is demonstrated by several examples.

Ultrasound microbial cell disrupters operating at around 20 kHz are often physically large and, due to significant heating, can be unsuitable for small sample volumes where biochemical integrity of the extracted product is required. Development of a compact device based on a 63.5-mm diameter, 6.5-mm thick tubular transducer for rapid cell disruption in small-volume samples in a high-intensity acoustic cavitation field with minimal temperature rises is described here. Suspensions of Saccharomyces cerevisiae were exposed to cavitation for various times in the compact device and a 20-kHz probe sonicator. Cell disruption was assessed by protein release and by staining. Yeast cell disruption was greater in the novel 267-kHz sonicator than in the 20-kHz probe sonicator for the same exposure time. A 1-dimensional (1-D) transfer matrix model analysis for piezoelectric resonators was applied to an axial cross-section of the tubular sonicator to predict frequencies of mechanical resonance in the sample volume associated with maximum acoustic pressure. Admittance measurements identified frequencies of electrical resonance. Ultrasonic cavitation noise peaks were detected by a hydrophone at both the mechanical and electrical resonances. Cell breakage efficiency was twice as great in terms of protein released per dissipated watt at the mechanical resonance predicted by the model, compared to those at the electrical resonance frequencies. The results form a basis for rational design of an ultrasound cell disruption technique for small-volume samples.

Background and Purpose: Recently, 3 clinical trials revealed encouraging results in recanalization and clinical outcome in acute stroke patients when 2-MHz transcranial Doppler monitoring was applied. This study investigated whether a 1.8-MHz commercial diagnostic ultrasound device has the potential to facilitate thrombolysis using an in vitro stroke model., Methods: Duplex-Doppler, continuous wave-Doppler, and pulsed wave (PW)-Doppler were compared on their impact on recombinant tissue plasminogen activator (rtPA)-mediated thrombolysis. Blood clots were transtemporally sonicated in a human stroke model. Furthermore, ultrasound attenuation of 5 temporal bones of different thickness was determined., Results: In comparison, only PW-Doppler accelerated rtPA-mediated thrombolysis significantly. Without temporal bone, PW-Doppler plus rtPA showed a significant enhancement in relative clot weight loss of 23.7% when compared with clots treated with rtPA only (33.9+/-5.5% versus 27.4+/-5.2%; P<0.0005). Ultrasound attenuation measurements revealed decreases of the output intensity of 86.8% (8.8 dB) up to 99.2% (21.2 dB), depending on temporal bone thickness (1.91 to 5.01 mm)., Conclusions: Without temporal bone, PW-Doppler significantly enhanced thrombolysis. However, because of a high attenuation of ultrasound by temporal bone, no thrombolytic effect was observed in our in vitro model, although Doppler imaging through the same temporal bone was still possible.

Ultrasound of 2 MHz frequency and 1.2 W/cm(2) acoustic intensity was applied to examine the effect of sonication on recombinant tissue-type plasminogen activator (rt-PA)-induced thrombolysis as well as on the distribution of plasminogen and t-PA within whole blood clots in vitro. Thrombolysis was evaluated quantitatively by measuring clot weight reduction and the level of fibrin degradation product D-dimer (FDP-DD) in the supernatant. Weight reduction in the group of clots treated both with ultrasound and rt-PA was 35.2% +/-6.9% which is significantly higher (p<0.0001) than in the group of clots treated with rt-PA only (19.9% +/-4.3%). FDP-DD level in the supernatants of the group treated with ultrasound and rt-PA increased sevenfold compared to the group treated with rt-PA alone, (14895 +/-2513 ng/ml vs. 2364 +/-725 ng/ml). Localization of fibrinolytic components within the clots was accomplished by using gel-entrapping technique and immunohistochemistry. Spatial distributions of t-PA and plasminogen showed clearly that ultrasound promoted the penetration of rt-PA into thrombi significantly (p<0.0001), and broadened the zone of lysis from 8.9 +/-2.6 microm to 21.2 +/-7.2 microm. We speculate that ultrasound enhances thrombolysis by affecting the distribution of rt-PA within the clot.

This paper introduces a novel ultrasonic capacitance transducer for operation at elevated gas temperatures of several hundred degrees Celsius. The transducer design is based on a metallic membrane foil and a backplate made of an electrically conducting substrate coated with an insulation layer. Guidelines are given for selecting suitable materials for the membrane foil, the backplate substrate, and the coating. Manufacturing techniques applied for fabrication of different transducer types are described in detail. Transducers tested were composed of titanium substrates with insulation layers of silicon nitride or of silicon substrates with silicon oxide coatings. Experimental setup and test procedures are described. Results of transducer characterization and performance tests at elevated temperatures are presented and discussed. Transducer functionality is proven for air temperatures of up to 500 degrees C.

A novel, h-shaped ultrasonic resonator was used to separate biological particulates. The effectiveness of the resonator was demonstrated using suspensions of the cyanobacterium, Spirulina platensis. The key advantages of this approach were improved acoustic field homogeneity, flow characteristics, and overall separation efficiency (sigma = 1 - ratio of concentration in cleared phase to input), monitored using a turbidity sensor. The novel separation concept was also effective under microgravity conditions; gravitational forces influenced overall efficiency. Separation of Spirulina at cleared flow rates of 14 to 58 L/day, as assessed by remote video recording, was evaluated under both microgravity (

Angiotensin II has been shown to exert complex effects on proximal tubular cell function and growth. To assess some of the direct effects on proximal tubular cells, changes in gene expression of selected cellular pathways were determined after exposure to angiotensin II. We used DNA microarrays to analyze multiple gene expression responses to increasing angiotensin II concentrations. Human proximal tubular cells were grown in flasks, and the presence of angiotensin type 1 receptor was confirmed by Western blot analysis. At passages 4-6, these cells were exposed to angiotensin II and harvested 4 h later and mRNA of the cells was extracted; 2 microg of mRNA was fluorescently conjugated for cDNA microarray hybridization. A custom-made DNA microarray was designed by selecting 300 human genes from 10 different functional systems and amplifying clones using polymerase chain reaction. Cells were subjected to 10 and 100 nM angiotensin II with paired untreated cells as controls. RNA was isolated, reverse transcribed, labeled and hybridized to the arrays and the ratios calculated. Ratios of > or =2.0 and < or =0.5 were considered significant. Coordinated changes were observed in genes of the hepatocyte nuclear factor 3 family (NHF3; HNF3A, HNF3B and HNF3G), in the E2F genes (E2F1, E2F3) and the interferon regulatory factors IRF1 and IRF5. Induction of the expression of transcription factors points towards complex regulation of gene expression upon angiotensin II exposure. Three genes involved in the dampening of oxidative stress were enhanced. Taken together, brief exposure of human tubular epithelial cells to angiotensin II elicited a marked induction of nuclear factors, antioxidant genes and hormones and hormone receptor genes. The quick activation of transcription factors by angiotensin II indicates that angiotensin II can directly initiate a cascade of expressional events in proximal tubular cells.

In addition to fibrinolytic enzymes, ultrasound has the potential to enhance thrombolysis. High frequency ultrasound has the advantage that a combination of diagnostic and therapeutic ultrasound with only one device is possible. Therefore, we investigated the optimal high frequency (2 MHz) ultrasound field characteristics and application mode in vitro. Continuous ultrasound significantly enhanced rt-PA mediated thrombolysis: in a travelling wave field thrombolysis was augmented by 49.0 +/- 14.7% and in a standing wave field by 34.8 +/- 7.3%. In an intermittent application mode (1Hz, 10Hz, 100Hz, 1kHz) most efficient results were obtained for both wave fields using 1 Hz (46.4 +/- 10.7% and 39.1 +/- 6.6%, respectively). Referring to a possible in vivo application our in vitro data suggests that an intermittent application of a 2 MHz high frequency ultrasound using a travelling wave field would be the most potent application for lysing blood clots.

Success of thrombolytic therapy depends on penetration of recombinant tissue plasminogen activator (rt-PA) into clots. Ultrasound (US) of therapeutic quality accelerates thrombolysis in vitro. As yet, only the effects of travelling acoustic waves on thrombolysis have been investigated, and the impact of standing acoustic waves has been neglected. In the present study, we examined the effects of standing and travelling US wave fields applied continuously for 1 h (frequency 2 MHz, acoustic intensity 1.2 W/cm(2)) on thrombolysis enhancement by measuring clot weight reduction and concentration of fibrin degradation product D-dimer (FDP-DD) produced from clots subjected to rt-PA. The level of FDP-DD was 1.8 times greater in travelling than in standing acoustic waves. Thrombolysis enhancement was 46.0 +/- 20.8% in standing and 116.8 +/- 23.1% in travelling acoustic waves. Travelling waves enhanced thrombolysis significantly more (p < 0.0001) than did standing waves., (Copyright 2002 World Federation for Ultrasound in Medicine & Biology)

The quantitative performance of a "single half-wavelength" acoustic resonator operated at frequencies around 3 MHz as a continuous flow microparticle filter has been investigated. Standing wave acoustic radiation pressure on suspended particles (5-microm latex) drives them towards the center of the half-wavelength separation channel. Clarified suspending phase from the region closest to the filter wall is drawn away through a downstream outlet. The filtration efficiency of the device was established from continuous turbidity measurements at the filter outlet. The frequency dependence of the acoustic energy density in the aqueous particle suspension layer of the filter system was obtained by application of the transfer matrix model [H. Nowotny and E. Benes, J. Acoust. Soc. Am. 82, 513-521 (1987)]. Both the measured clearances and the calculated energy density distributions showed a maximum at the fundamental of the piezoceramic transducer and a second, significantly larger, maximum at another system's resonance not coinciding with any of the transducer or empty chamber resonances. The calculated frequency of this principal energy density maximum was in excellent agreement with the optimal clearance frequency for the four tested channel widths. The high-resolution measurements of filter performance provide, for the first time, direct verification of the matrix model predictions of the frequency dependence of acoustic energy density in the water layer.

Petunia hybrida cell suspension cultures were exposed to ultrasonic standing wave fields at 2.43 MHz for 40 min with mean sound pressures (within homogenous sound fields) varying from 0 (control) to ca. 1.1 MPa. Mean (+/- s.d.; n =6-9) cell viability was reduced to 87+/-10% at 0.6 MPa and to 59 +/- 23% at 1.1 MPa, compared to an initial control value of 92 +/- 6% (P <0.05). Mean (n = 3) cell alkaline phosphatase concentration increased linearly with sound pressure from a control value of 0.006+/-0.001 to 0.02+/-0.01 Sigma-Units microg(-1) protein at 1.1 MPa (P<0.05). Similarly, mean cell catalase activity increased from a control value of 0.020 +/- 0.003 to 0.026 +/- 0.008 arbitrary units at 1.1 MPa. In contrast, mean cellular lactate dehydrogenase concentration was unchanged. These observations indicate that cellular repair processes associated with increased alkaline phosphatase activity might be triggered by physical cell damage caused by ultrasound. The observed increase in catalase activity suggests increasing production of free radicals and other sonochemicals, which warrants further study. The absence of changes in lactate dehydrogenase indicates that there was no major damage to respiratory pathways or to overall cellular integrity.

The rotating wall vessel is optimized for suspension culture, with laminar flow and adequate nutrient delivery, but minimal shear. However, higher shears may occur in vivo. During rotating wall vessel cultivation of human renal cells, size and density of glass-coated microcarrier beads were changed to modulate initial shear. Renal-specific proteins were assayed after 2 days. Flow cytometry antibody binding analysis of vitamin D receptor demonstrated peak expression at intermediate shears, with 30% reduction outside this range. Activity of cathepsin C showed the inverse pattern, lowest at midshear, with twofold increases at either extreme. Dipeptidyl-peptidase IV had no shear dependence, suggesting that the other results are specific, not universal, changes in membrane trafficking or protein synthesis. On addition of dextran, which changes medium density and viscosity but not shear, vitamin D receptor assay showed no differences from controls. Neither cell cycle, apoptosis/necrosis indexes, nor lactate dehydrogenase release varied between experiments, confirming that the changes are primary, not secondary to cell cycling or membrane damage. This study provides direct evidence that mechanical culture conditions modulate protein expression in suspension culture.

Hypertension induced by long-term infusion of angiotensin II (Ang II) is associated with augmented intrarenal Ang II levels to a greater extent than can be explained on the basis of the circulating Ang II levels. Although part of this augmentation is due to AT(1) receptor-dependent internalization, the intracellular compartments involved in this Ang II accumulation remain unknown. In the present study, we sought to determine whether Ang II trafficking into renal cortical endosomes is increased during Ang II hypertension, and if so, whether the AT(1) receptor antagonist, candesartan, prevents this accumulation. Compared with controls (n=12; 114+/-2 mm Hg), Ang II-infused rats (n=12; 80 ng/kg/min, SC, for 13 days) developed hypertension with systolic blood pressure rising to 185+/-4 mm Hg by Day 12. In Ang II hypertensive rats, plasma renin activity was suppressed, whereas plasma and kidney Ang II levels were increased by 3-fold (348+/-58 versus 119+/-16 fmol/mL) and 2-fold (399+/-39 versus 186+/-26 fmol/g). Intracellular endosomal Ang II levels were increased by more than 10-fold (1100+/-283 versus 71+/-12 fmol/mg protein), whereas intermicrovillar cleft Ang II levels were increased by more than 2-fold (88+/-22 versus 37+/-7 fmol/mg protein). Flow cytometric analysis detected significant increases in AT(1A) receptor antibody binding in endosomal and intermicrovillar clefts of Ang II-infused rats. The hypertension induced by Ang II was prevented in rats treated concurrently with candesartan (2 mg/kg/d, 119+/-3 mm Hg). Candesartan treatment (n=8) also prevented increases in kidney (215+/-19 fmol/g), endosomal (96+/-29 fmol/mg protein), and intermicrovillar cleft Ang II levels (11+/-2 fmol/mg protein). These results indicate that there is substantial intracellular accumulation of angiotensin peptides in renal cortical endosomes during Ang II-dependent hypertension via an AT(1) receptor-mediated process.

Retention and manipulation of microbial cells through exploitation of ultrasonic forces has been reported as a novel cell immobilisation technique. The spatial ordering of yeast cells, within suspensions subjected to an ultrasonic standing wave field, was analysed for the first time. A technique, based on 'freezing' the spatial arrangement using polymer gelation was developed. The resultant gel was then sectioned and examined using microscopic techniques. Light Microscopy confirmed the presence of specific regions in the ultrasonic field, where the cells are organised into bands corresponding to the standing waves' pressure nodal planes. Computer Image Analysis measurement of several physical parameters associated with this cell distribution matched the values derived from the theoretical model. The spatial cell-cell re-arrangement within each band and uneven distribution along the nodal planes have been analysed by Scanning Electron Microscopy. These results complement the ongoing study of the process of immobilisation of microbial cells by ultrasound standing waves.

Three-dimensional suspension culture is a gravity-limited phenomenon. The balancing forces necessary to keep the aggregates in suspension increase directly with aggregate size. This leads to a self-propagating cycle of cell damage by balancing forces. Cell culture in microgravity avoids this trade-off. We determined which genes mediate three-dimensional culture of cell and tissue aggregates in the low-shear stress, low-turbulent environment of actual microgravity. Primary cultures of human renal cortical cells were flown on the space shuttle. Cells grown in microgravity and ground-based controls were grown for 6 days and fixed. RNA was extracted, and automated gene array analysis of the expression of 10, 000 genes was performed. A select group of genes were regulated in microgravity. These 1,632 genes were independent of known shear stress response element-dependent genes and heat shock proteins. Specific transcription factors underwent large changes in microgravity including the Wilms' tumor zinc finger protein, and the vitamin D receptor. A specific group of genes, under the control of defined transcription factors, mediate three-dimensional suspension culture under microgravity conditions.

Recent studies have shown that there is no loss of cell viability when the cells are subjected to ultrasonic standing wave fields in acoustic cell retention systems. These systems are characterised by waves that spatially vary in pressure amplitude in the direction of sound propagation. In this work an anechoic 'one-dimensional' sonication chamber has been developed that produces propagating waves, which differ from standing waves in that the pressure amplitude remains constant as the wave travels in a medium with negligible attenuation. The viability of yeast cell suspensions as a function of treatment time was investigated during exposure to both standing and propagating wave fields with frequencies slightly above 2 MHz. The influence of 12% (vol/vol) of ethanol in water on the spatial arrangement of the cells in suspension was also studied. Changes in yeast cell morphology caused by the different types of suspension media and the ultrasonic treatment were examined by transmission electron microscopy (TEM). The agglomeration of yeast cells within the pressure nodal planes appears to minimise damaging effects due to ultrasonic fields.

Purpose: The proteins which constitute the final common pathway linking receptors on cell surfaces to the inflammatory cascade have recently been identified and cloned. Central to activation of this inflammatory cascade is translocation from cytosol to nucleus of the nuclear transcription factor known as nuclear factor-kappa B (NF-kappaB). The purpose of this study was to determine whether NF-kappaB cascade plays a role in lipopolysaccharide (LPS)-induced inflammation of the mouse urinary bladder., Materials and Methods: Bladder inflammation was induced in anesthetized mice by intravesical instillation of lipopolysaccharide (LPS) and quantified by morphometric analysis. The NK-1 receptors for substance P were quantified by flow cytometry. LPS-induced degradation of inhibitory IkappaB subunit was quantified by Western blotting analysis and translocation of NF-kappaB protein from cytosol to the nucleus was determined by confocal microscopy and Western blotting analysis. In addition, we determine the effect of lactacystin, a proteosome inhibitor, on LPS-induced IkappaB degradation and NF-kappaB translocation, NK-1 receptor fluorescence intensity, and bladder inflammation., Results: LPS instillation into the mouse bladder resulted in time dependent loss of the inhibitory IkappaB subunit of the NF-kappaB protein complex. IkappaB cleavage was followed by translocation of NF-kappaB from the cytosol to the nucleus. This was associated with increased expression of an NF-kappaB dependent inflammatory component, the NK-1 receptor. Pretreatment of mouse bladders with the NF-kappaB inhibitor, lactacystin, prevented cleavage of IkappaB in a dose-dependent manner. Lactacystin prevented increases in the NF-kappaB dependent inflammatory cascade components such as the NK-1 receptor. At the whole tissue level, the marked inflammatory infiltrate and mucosal breakdown associated with LPS administration was completely abolished by lactacystin., Conclusion: NF-kappaB mediates many features of urinary bladder inflammation induced by LPS. The NF-kappaB cascade is an important target for anti-inflammatory management of cystitis.

Exposure of Petunia hybrida cell suspensions to ultrasound at a frequency of 2.43 MHz in a standing wave field at an energy density of 70 Jm-3 (pressure amplitude of 0.78 MPa) decreased their mean viability to 35% after 20 min of sonication. A comparison of propagating wave and standing wave treatments at equal frequency (2.15 MHz) and energy density (8.5 Jm-3) showed, in the first case, a rapid decline in mean viability of cells (to 30% after 10 min of sonication) and, in the second case, a retaining of the initial viability (95%), respectively. Cells sonicated 4 days after subculture were more sensitive than cells sonicated 2 or 6 days after transfer to new culture medium. It was concluded that cellular viability depends primarily on the acoustic energy density, the exposure time, and the mechanical properties of the cells determined by age. As a consequence of the trapping of cells in the anti-node planes of the standing wave, propagating wave fields reduced cellular viability compared with standing wave fields at equal energy density.

Some physiological/morphological changes have been reported before, when suspended yeasts have been irradiated with well-defined ultrasonic standing, as well as propagating, plane waves around 2.2 MHz, as used in ultrasonic coagulation, e.g., for cell filtering. Thus we used yeast as a biological model to explore the reasons for both those morphology changes and some unusual macroscopic behaviour in the case of water-rich ethanol mixtures when used as carrier liquid. When the cells were suspended in 12% (v/v) ethanol-water mixture separation was greatly reduced; the yeast cells were not retained in the pressure nodal planes of the standing wave, but mixed turbulently through the separation system. How this behaviour alters the efficiency of retention/immobilisation was measured. As the viability of the yeast was decreased as well the morphology of the cells was examined using transmission electron microscopy. Two effects, according to the type of assessment, were evident; a disruption of the cells vacuole and also damage to the cell wall/membrane complex. The extent of the alterations in vacuole structure with sonication time, utilising a fluorescent vacuole membrane dye, was measured. Transient cavitation was not detected and thus could be excluded as being responsible for the observed effects. Other possible reasons for the disruption of the intracellular compartments may be acoustic pressure, displacement or other, secondary effects like (sub) harmonic cavitation. The investigations contribute to a better understanding of the physical conditions experienced when a cell is stressed in a high-frequency ultrasonic wave in the MHz range.

A comparison is given between piezoelectrically excited bulk acoustic wave (BAW) and surface acoustic wave (SAW) elements with respect to their primary sensitivity functions and principal capabilities for sensor applications. The importance of mode purity for high dynamic range sensors is emphasized. Characteristic sensor examples are reviewed, and the special demands on the electronics for BAW and SAW elements in the sensor field are described (e.g., cable problem, wireless SAW sensors). For a fair evaluation, a performance figure, SQ, defined as the product of reduced sensitivity S and resonator Q-value, is introduced. The potential of alternative piezoelectric materials for future sensor developments is discussed briefly.

This paper describes a novel quartz crystal sensor for measurement of the density-viscosity product of Newtonian liquids. The sensor element consists of two piano-convex AT-cut quartz crystals vibrating in a thickness-shear mode with the liquid sample in between. This special set-up allows suppression of disturbing resonances in the liquid layer. Such resonances are generated in the common single-plate arrangements due to compressional waves caused by spurious out-of-plane displacements of the shear vibrating finite plate. The primary measurands of the sensor are the fundamental resonance frequency and the associated resonance Q-value, which are influenced by the viscously entrained liquid contacting the quartz surface. The sensor allows the measurement of samples with viscosities from almost zero (air!) up to 200 cP with a sample volume of 130 microl.

A double-chamber ultrasonic resonance field device was used for the separation and retention of animal cells. By controlling operational parameters such as flow and power input, the device can retain viable cells more efficiently, allowing for selective removal of nonviable cells and cell debris. A simple model describing the forces acting on spherical particles in a sound field (primary radiation force, Bernoulli force, secondary radiation force) is presented. Field stability increases with decreasing average flow rates and increasing power input. At very high field stability, as achieved with low flow rates and high power input, the selectivity for viable cells is reduced, due to the efficient retention of all types of particles. At high flow rates and resulting low field stability, selectivity is also reduced, due to poor separation efficiency, resulting in equally low retention of viable cells, nonviable cells, and cell debris.

This article describes two types of flow-through cell retention devices based on the concept of layered piezoelectric resonators. A single-chamber device is compared to a novel optimized steam-sterilizable prototype ultrasonic cell separator with improved acoustic design and an integrated cooling circuit, eliminating the problem of local temperature increase caused by the high amplitudes necessary to achieve the separation of animal cells with low acoustic contrast. This setup yields highly reproducible results and is ideal for studying the long-term effects of ultrasonic sound fields and separation efficiency. The novel two-chamber system has the potential for scaleability due to the reduction in thermal and acoustic flow, increased field stability, and separation efficiency. Finally, the effect of power input on separation and cell viability is reported. Such flow-through cell retention systems could be used as systems to retain biomass within the fermentor or as a substitute for centrifugation, with the major advantage of eliminating high-speed rotational motion.

The time taken to perform diagnostic agglutination tests can be significantly reduced by applying an ultrasonic standing wave field to a droplet of reactants held in a capillary tube. Avian erythrocytes, bacteria and latex particles from commercially available test kits were agglutinated in 15 s, 5 min, and 1 min respectively. These times compare favourably with the times of 30 min, 4 h, and 8 min required for agglutination by the methods prescribed for the respective kits. No loss in sensitivity or specificity was observed with the ultrasonic method. A multi-test procedure is also described whereby a series of five droplets loaded in a single capillary can be tested in less than 4 min by drawing the capillary along the axis of the ultrasonic field of a ring transducer.

The Butterworth-Van Dyke equivalent circuit for description of the electrical behavior of piezoelectric bulk resonators is considered. The motional capacitance, C(1), in the circuit characterizes the strength of piezoelectric excitability of a vibration mode. For layered one-dimensional (1-D) structures this parameter can be calculated from the admittance given by the transfer matrix description of H. Nowotny and E. Benes (1987). Introducing the equivalent area of a vibration mode, the calculation is generalized for the three-dimensional (3-D) case of thickness-mode vibration amplitudes varying only slowly in the lateral directions. Detailed formulae are given for the case of singly rotated quartz crystals or ultrasonic transducers with additional layers on one or two sides. Good agreement of the calculated C (1) with experimental data is shown for mass-loaded planoconvex AT-cut quartz crystals.

Twenty-three cases of laryngeal papilloma have been treated and followed for four years utilizing laser excision and laser excision/immunotherapy. Fourteen cases responded well to laser excision alone, nine did not and immunotherapy was instituted as adjunctive treatment. To date, immunotherapy has contributed little to the relief in this group of refractory cases.