Dynamic Resonance Research Articles

Dynamic resonance frequency control for a resonant-type smooth impact drive mechanism actuator

Multimodal piezoelectric actuators combine multiple vibration modes to achieve specific motions for precise actuation, or to enhance the output performance. For such a combination, the operating frequency ratio is necessarily an integer constraint. However, the resonance frequencies of target modes can be mismatched in assembly, and shift easily during operation, limiting the actuator applications. Therefore, we proposed a dynamic resonance frequency control method for multimodal piezoelectric actuators and applied it to a resonant-type smooth impact drive mechanism actuator. Passive piezoelectric parts were deployed on a Langevin transducer and connected with a field effect transistor (FET) switch. As a pulse width modulation (PWM) signal continuously adjusting the electrical boundary of these passive parts, the first longitudinal L1 mode’s resonance frequency was dynamically controlled to match the third L3 mode’s frequency with a ratio of two, generating a quasi-sawtooth displacement to drive a rotor. Experimental results indicated that the prototype’s L1 frequency can be continuously tuned from 25.715 to 24.76 kHz at 27 ℃, and the corresponding frequency ratio was adjusted from 1.953 to 2.028. Multimodal resonance frequency static matching was confirmed by changing the switching signal’s duty ratio. The L1 and L3 mode driving voltages were 50 Vp-p, and 23 Vp-p, respectively, and the speed of the rotor was 133.7 r/min. Dynamic resonance frequency control was realized with a feedback control system. As the driving PZT temperature increased to 70.5 ℃, both modes were matched and maintained resonance for 400 s. The results demonstrate that this method is conducive to improving actuator performance.

Photogrammetry of Ultrafast Excited-State Intramolecular Proton Transfer Pathways in the Fungal Pigment Draconin Red.

Proton transfer processes of organic molecules are key to charge transport and photoprotection in biological systems. Among them, excited-state intramolecular proton transfer (ESIPT) reactions are characterized by quick and efficient charge transfer within a molecule, resulting in ultrafast proton motions. The ESIPT-facilitated interconversion between two tautomers (PS and PA) comprising the tree fungal pigment Draconin Red in solution was investigated using a combination of targeted femtosecond transient absorption (fs-TA) and excited-state femtosecond stimulated Raman spectroscopy (ES-FSRS) measurements. Transient intensity (population and polarizability) and frequency (structural and cooling) dynamics of -COH rocking and -C=C, -C=O stretching modes following directed stimulation of each tautomer elucidate the excitation-dependent relaxation pathways, particularly the bidirectional ESIPT progression out of the Franck-Condon region to the lower-lying excited state, of the intrinsically heterogeneous chromophore in dichloromethane solvent. A characteristic overall excited-state PS-to-PA transition on the picosecond timescale leads to a unique "W"-shaped excited-state Raman intensity pattern due to dynamic resonance enhancement with the Raman pump-probe pulse pair. The ability to utilize quantum mechanics calculations in conjunction with steady-state electronic absorption and emission spectra to induce disparate excited-state populations in an inhomogeneous mixture of similar tautomers has broad implications for the modeling of potential energy surfaces and delineation of reaction mechanisms in naturally occurring chromophores. Such fundamental insights afforded by in-depth analysis of ultrafast spectroscopic datasets are also beneficial for future development of sustainable materials and optoelectronics.

V12-11 ROBOTIC SACROHYSTEROPEXY WITH CONCURRENT RECTOPEXY USING FASCIA LATA GRAFT

You have accessJournal of UrologyCME1 Apr 2023V12-11 ROBOTIC SACROHYSTEROPEXY WITH CONCURRENT RECTOPEXY USING FASCIA LATA GRAFT Poone Shoureshi, Alexandra Dubinskaya, David Magner, and Karyn S. Eilber Poone ShoureshiPoone Shoureshi More articles by this author , Alexandra DubinskayaAlexandra Dubinskaya More articles by this author , David MagnerDavid Magner More articles by this author , and Karyn S. EilberKaryn S. Eilber More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003347.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Sacrohysteropexy with concurrent rectopexy can be performed in women of childbearing age, with multicompartment prolapse, who wish to preserve their uterus. There is limited data regarding the use of mesh for prolapse repair in this population, therefore a biologic graft is often used to decrease the risk of contamination with colorectal surgery and allow for future pregnancy. We present the surgical management of prolapse repair in a young woman who presented with uterine and rectosigmoid prolapse, causing rectal outlet obstruction. METHODS: Our patient is a 21-year-old woman with over a decade of severe constipation and abdominal pain. Her past medical history includes anxiety, depression and sexual abuse. She previously underwent robotic rectopexy for intra-rectal intussusception and mucosal prolapse with immediate improvement in her symptoms; however, two months after rectopexy, she suffered from persistent abdominal pain and severe difficulty passing stool. Dynamic resonance imaging demonstrated descent of the bladder with significant uterine prolapse, causing impingement of rectum and rectocele, blocking the evacuation of stool. The patient was thus indicated for concurrent sacrohysteropexy and rectopexy. RESULTS: She underwent a robotic procedure. Given the patient’s age, in an effort to preserve future child-bearing potential, we elected to perform the surgery with a biologic graft made of fascia lata. The sacrohysteropexy was performed by suturing the graft to the posterior cervix. Intraoperatively she was noted to have an intact enterocele repair and posterior rectopexy from her previous surgery; however, the rectosigmoid attachment appeared to have stretched, creating an angulation at the rectosigmoid. This was corrected by performing a rectopexy to the fascia lata graft. The patient was discharged home the day of surgery without incident. CONCLUSIONS: Biologic grafts can be used for multicompartment prolapse repair in women of child-bearing age. Fascia lata provides a safe alternative to mesh to allow for future pregnancy. Also, sacrohysteropexy with concurrent rectopexy can be performed with same day discharge. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1068 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Poone Shoureshi More articles by this author Alexandra Dubinskaya More articles by this author David Magner More articles by this author Karyn S. Eilber More articles by this author Expand All Advertisement PDF downloadLoading ...

Shadow Enhancement Using 2D Dynamic Stochastic Resonance for Hyperspectral Image Classification

With the development of remote sensing technology, classification has become a meaningful way to explore the rich information in hyperspectral images (HSIs). However, various environmental factors may cause noise and shadow areas in HSIs, resulting in weak signals and difficulties in fully utilizing information. In addition, classification methods based on deep learning have made considerable progress, but features extracted from most networks have much redundancy. Therefore, a method based on two-dimensional dynamic stochastic resonance (2D DSR) shadow enhancement and convolutional neural network (CNN) classification combined with an attention mechanism (AM) for HSIs is proposed in this paper. Firstly, to protect the spatial correlation of HSIs, an iterative equation of 2D DSR based on the pixel neighborhood relationship was derived, which made it possible to perform matrix SR in the spatial dimension of the image, instead of one-dimensional vector resonance. Secondly, by using the noise in the shadow area to generate resonance, 2D DSR can help increase the signals in the shadow regions by preserving the spatial characteristics, and enhanced HSIs can be obtained. Then, a 3DCNN embedded with two efficient channel attention (ECA) modules and one convolutional block attention module (CBAM) was designed to make the most of critical features that significantly affect the classification accuracy by giving different weights. Finally, the performance of the proposed method was evaluated on a real-world HSI, and comparative studies were carried out. The experimental results showed that the proposed approach has promising prospects in HSIs’ shadow enhancement and information mining.

Experimental investigation of engineering properties of silica sand filled mortars containing high doses of SWCNT

Recently, great efforts have been made by researchers on the mixture of electrically conductive concretes that have been developed for different purposes. In this study, an experimental research was carried out on electrically conductive mortar mixtures especially for shell elements produced for building facade cladding. Six different mixtures were produced, including the non-conductive reference mixture. Single-walled carbon nanotube (SWCNT) was used as nano-sized conductive additive material. SWCNT was added at 0.2% and 0.3% of cement weight. SF was added to the same mixtures as another group at the rate of 4% by total weight. 2, 14, 28, 90 and 180 days electrical resistivities of the obtained conductive mortar samples were measured. As a non-destructive method, dynamic resonance testing was performed and the 28-day damping rates of the samples were determined. Ultrasonic pulse velocity (UPV) and Leeb hardness tests were performed, respectively, by using other non-destructive testing methods to obtain information about the internal structure voids and surface hardness of the samples. SWCNT, which causes low machinability and therefore internal structure voids, caused a decrease in compressive strength and flexural strength, as well as a significant increase in electrical conductivity.

Highlighting the effect of heterogeneous blood perfusion on radio-frequency ablation of human brain tumors: An image-based numerical investigation

Radio-frequency ablation (RFA) is a minimally invasive treatment that can provide highly localized and precise cancer therapy. Despite these advantages, its application in clinical practice remains limited. This is primarily due to the insufficient ablation volume, where blood perfusion plays a significant role. In this study, computational modeling is applied to examine the effects of heterogeneous blood perfusion on the tissue temperature, resultant thermal damage, and ablation volume in the RFA treatment. Two patients' heterogeneous blood perfusion and 3D brain tumor geometry are extracted from their dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) data. This patient-specific information is imported into the bioheat transfer model developed in OpenFOAM to predict thermal effects. Results show that the heterogeneous blood perfusion leads to deeper heat penetration in the tumor tissue compared to the simulation in which blood perfusion is assumed to be uniform across the entire tumor. On average, the predicted tissue temperature and ablation volume are 10–11% and 30–38% higher for both patients, respectively, when the heterogeneous blood perfusion is adopted. In addition, the ablation volume is highly susceptible to the applied RF voltage and coolant temperature. These two factors can be optimized to maximize the treatment. However, the optimal settings vary for each patient, highlighting the demand for patient-specific design. Results obtained from this study can assist clinicians and surgeons in optimizing RFA parameters for a specific patient that can improve the treatment efficacy.

Seeking for resonances in unitarized one-loop graviton-graviton scattering

Some effective field theories exhibit dynamical resonances that, when properly included, mitigate their bad behavior at high energies. Unitarization of the partial wave amplitudes is the preferred method to unveil such resonances. Interpreting the Einstein-Hilbert theory in the spirit of effective Lagrangians, we implement the inverse amplitude method and unitarize the one-loop level graviton-graviton scattering in pure gravity. Due to the presence of infrared divergences, the analysis requires a careful treatment of the infrared region and the introduction of infrared regulators, carefully selected in order to fulfill perturbative unitarity.

Dynamic correlation and risk resonance among industries of Chinese stock market: New evidence from time–frequency domain and complex network perspectives

To sustain market stability, it is crucial to research the impact of risk resonance across industries. In this paper, we demonstrate the dynamic risk resonance between various sectors in the Chinese market. To do so, by using a recently developed method that divides spillover measures based on variance decompositions into their components at different frequency ranges, a set of frequency spillover matrices is obtained to show the overall risk resonance within sectors. Second, we use a complex network to investigate the risk contagion path among different industries. The research results show that: (1) the risk resonance effect varies significantly over time; (2) during our sample period, the transportation and utilities industries are net transmitters; (3) the risk resonance mechanism is frequency dependent. Spillovers generated at low-frequency, extreme occurrences have a long-lasting effect on the industry’s risk resonance; and (4) extreme events such as the financial crisis and the COVID-19 will enhance the risk resonance effect. The results of our research can provide a reference for market participants to formulate corresponding regulatory and investment strategies.

Analysis of dynamic acoustic resonance effects in a sonicated gas–liquid flow microreactor

In this work, we characterize acoustic resonance phenomena occurring between gas bubbles in a segmented gas-liquid flow in a microchannel irradiated with a frequency around 500kHz. A large acoustic amplitude can be reached, leading to gas-liquid interface deformation, atomization of micrometer sized droplets, and cavitation. A numerical approach combining an acoustic frequency-domain solver and a Lagrangian Surface-Evolver solver is introduced to predict the acoustic deformation of gas-liquid interfaces and the dynamic acoustic magnitude. The numerical approach and its assumptions were validated with experiments, for which a good agreement was observed. Therefore, this numerical approach allows to provide a description and an understanding of the acoustic nature of these phenomena. The acoustic pressure magnitude can reach hundreds of kPa to tens of MPa, and these values are consistent with the observation of atomization and cavitation in the experiments. Furthermore, volume of fluid simulations were performed to predict the atomization threshold, which was then related to acoustic resonance. It is found that dynamic acoustic resonance gives rise to atomization bursts at the gas bubble surface. The presented approach can be applied to more complex acoustic fields involving more complex channel geometries, vibration patterns, or two-phase flow patterns.

Dynamic stable ring resonator for high-power continuous single-frequency lasers: conditions for a compact resonator.

When considering dynamically stable resonators, ring lasers are good choices because they have a stability interval that is twice as large as that of linear resonators and sensitivity to misalignment decreasing with pump power; however, the literature does not provide easy design guidelines. A ring resonator utilizing Nd:YAG side pumped by diodes allowed single-frequency operation. The output single-frequency laser had good output characteristics; however, the overall length of the resonator did not allow for building a compact device with low misalignment sensitivity and larger spacing between longitudinal modes which could improve single-frequency performance. Based on previously developed equations, which allow for ease of design of a ring dynamically stable resonator, we discuss how to build an equivalent ring resonator, aiming to building a shorter resonator with the same stability zone parameters. The study of the symmetric resonator containing a pair of lenses allowed us to find the conditions to build the shortest possible resonator.

Double stochastic resonance in neuronal dynamics due to astrocytes

A continuously growing body of evidence indicates that astrocytes, which is the most abundant sub-type of glial cells in the nervous system, not only provide structural and metabolic support to neurons, but also they are essential sentinels and dynamic modulators of neuronal and synaptic functions. However, the potential constructive role of astrocytes in information processing at the neuronal and synaptic level, and especially also in the presence of different noise sources in the neural system, is yet unclear. With this in mind, we here study the phenomenon of stochastic resonance – the enhanced detection of weak signals in the presence of noise – in neuronal dynamics by means of a mathematical model that includes interactions between the neuron and the astrocyte. We show that astrocytes may evoke a second peak in the neuronal detection of weak signals in dependence on the noise intensity, which is the hallmark of double stochastic resonance. We explore in detail the mechanisms underlying this discovery, in particular focusing on the determinants of astrocytic function and their role in the emergence of the second stochastic resonance peak. Our research thus provides fundamental insights into the possible roles of astrocytes in inherently noisy neuronal information processing.

Spectacle of Endings: In an “Endless Present”

This Introduction to the special issue on “Creative Endings” thinks across intensities and temporalities to consider the force of “endings” in the contemporary political moment: the multiple timespaces within them, endings as temporalities in their own right, experienced forcefully, unequally, and as generative of dynamic emotional resonances. Whilst often stated, endings remain under-theorised in the discipline. Yet endings are a central form through which the assemblage of representations, materialities, structures and the more-than representational are organised in the orchestration and deliverance of political work. This introduction, and the various papers that follow, begin to address the gap in thinking, by introducing intensities and temporalities as ways to work with both the representational and more-than-representational forces of endings, drawing upon examples from contemporary politics. From here, we propose the creative arts, in occupying the threshold of the representational/more-than-representations, as well placed to intervene on endings. We think the creative arts can help us to know, represent, and intervene in various ends within the current political moment, through their attunement, specifically, to liveness, form and feeling.

99m-Tc MDP Bone Scan Image Enhancement using Pipeline Application of Dynamic Stochastic Resonance Algorithm and Block-Matching 3D Filter.

In this pilot study, we have proposed and evaluated pipelined application of the dynamic stochastic resonance (DSR) algorithm and block-matching 3D (BM3D) filter for the enhancement of nuclear medicine images. The enhanced images out of the pipeline were compared with the corresponding enhanced images obtained using individual applications of DSR and BM3D algorithm. Twenty 99m-Tc MDP bone scan images acquired on SymbiaT6 SPECT/CT gamma camera system fitted with low-energy high-resolution collimators were exported in DICOM format to a personal computer and converted into PNG format. These PNG images were processed using the proposed algorithm in MATLAB. Two nuclear medicine physicians visually compared each input and its corresponding three enhanced images to select the best-enhanced image. The image quality metrics (Brightness, Global Contrast Factor (GCF), Contrast per pixel (CPP), and Blur) were used to assess the image quality objectively. The Wilcoxon signed test was applied to find a statistically significant difference in Brightness, GCF, CPP, and Blur of enhanced and its input images at a level of significance. Images enhanced using the pipelined application of SR and BM3D were selected as the best images by both nuclear medicine physicians. Based on Brightness, Global Contrast Factor (GCF), CPP, and Blur, the image quality of our proposed pipeline was significantly better than enhanced images obtained using individual applications of DSR and BM3D algorithm. The proposed method was found to be very successful in enhancing details in the low count region of input images. The enhanced images were bright, smooth, and had better target-to-background ratio compared to input images. The pipelined application of DSR and BM3D algorithm produced enhancement in nuclear medicine images having following characteristics: bright, smooth, better target-to-background ratio, and improved visibility of details in the low count regions of the input image, as compared to individual enhancements by application of DSR or BM3D algorithm.

Correlation of multiparametric MRI with histopathological grade of peripheral zone prostate carcinoma.

Prostatic cancer is the second most common malignant tumor in men. Preoperative grading of prostate cancer is important for its management. Our objective is to compare individual and combined detection rates of T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI), and magnetic resonance spectroscopy (MRS) for prostate cancer with histopathological diagnosis as its golden standard. Forty-four patients with positive digital rectal examination (DRE) findings and elevated prostate specific antigen (PSA), underwent multiparametric MRI (Mp-MRI). T2WI, DWI, DCE-MRI and MRS were done in all the patients. Cognitive magnetic resonance-transrectal ultrasound (MR-TRUS) fusion biopsy was done in all the patients. Sensitivity and specificity of T2WI, DWI, DCE-MRI, and Prostate Imaging - Reporting and Data System PIRADS version 2 was obtained. Apparent diffusion coefficient (ADC) value and choline/citrate ratio were obtained for each lesion and correlated with histopathological grade. The mean age of the patients was 68.7 ± 10.1 years, and the mean serum PSA level was 58.1 ± 22.4 ng/dL. Of the 38 lesions in peripheral zone, 33 (87%) had histopathologically proven prostate cancer. T2WI had a sensitivity and specificity of 75.8% and 80% and DWI had a sensitivity and specificity of 90.9% and 80%, respectively, for detection of malignant prostatic lesion. The mean ADC values for prostate cancer, prostatitis, and normal prostatic parenchyma were 0.702 ± 0.094 × 10-3 mm2/sec, 0.959 ± 0.171 × 10-3 mm2/sec, and 1.31 ± 0.223 × 10-3 mm2/sec, respectively. Type 3 curve has lower sensitivity (45.5%) but high specificity (80%) for diagnosing prostate cancer. DWI can be useful to differentiate benign from malignant prostatic lesions, and low-grade from high-grade prostate carcinoma. ADC value has a positive correlation with histopathological grade of prostate cancer.

Parametric Analysis of Electrostatic Comb Drive for Resonant Sensors Operating under Atmospheric Pressure

The microelectrostatic comb resonator’s issues with high driving voltage and strong feed‐through coupling noise limit its practical use. In earlier studies, the design and structural optimization of microcomb resonators generally focused on lowering beam stiffness and raising electrostatic force density to enhance resonance displacement and lower driving voltage. However, for a microresonator that performs high‐speed resonance in the air, it is required to consider the three influencing elements of the electrostatic field, structural mechanics, and fluid mechanics to achieve the best dynamic resonance amplitude. In this paper, the parametric analysis of the comb‐driven resonator is carried out. First, the comb‐driven electrostatic force and all air‐damping terms are investigated using an electrostatic force analytical model considering edge effects, a damping analytical model simplified based on the thin‐film damping model, and the finite element model. The analysis results agree with the simulated results. To more accurately quantify the dynamic electrostatic force and damping coefficient, the electrostatic–structure–fluid three‐field indirect coupling model was used, and the law of the resonant amplitude of the resonator as a function of the structural parameters was obtained. The results show that, for the electrostatic comb resonator that oscillates at atmospheric pressure, to obtain a high‐voltage driving efficiency, a thin polysilicon film can be used to design narrow comb fingers that are dense in the vertical direction and loose in the lateral direction. To validate the accuracy of the model and the results of parameter analysis, an electrostatic comb‐drive resonator with shapes optimized from numerical simulations was fabricated. The results show that the driving efficiency is enhanced by 102%, with the chip area increased by 29%, which shows the superiority of parameter optimization.

Feshbach resonances in the F + CHD3 → HF + CD3 reaction.

The signature of dynamics resonances was observed in the benchmark polyatomic F + CH4/CHD3 reactions more than a decade ago; however, the dynamical origin of the resonances is still not clear due to the lack of reliable quantum dynamics studies on accurate potential energy surfaces. Here, we report a six-dimensional state-to-state quantum dynamics study on the F + CHD3 → HF + CD3 reaction on a highly accurate potential energy surface. Pronounced oscillatory structures are observed in the total and product rovibrational-state-resolved reaction probabilities. Detailed analysis reveals that these oscillating features originate from the Feshbach resonance states trapped in the peculiar well on the HF(v' = 3)-CD3 vibrationally adiabatic potential caused by HF chemical bond softening. Most of the resonance structures on the reaction probabilities are washed out in the well converged integral cross sections (ICS), leaving only one distinct peak at low collision energy. The calculated HF vibrational state-resolved ICS for CD3(v = 0) agrees quantitatively with the experimental results, especially the branching ratio, but the theoretical CD3 umbrella vibration state distribution is found to be much hotter than the experiment.

Effects of single-walled carbon nanotubes and steel fiber on recycled ferrochrome filled electrical conductive mortars

The production of electrically conductive concrete was introduced years ago among construction materials, generally for anti-icing. The present study investigates the electrical, mechanical, dynamic, and microstructural properties of recycled ferrochrome filled cementitious mortars, containing single-walled carbon nanotubes (SWCNTs) and steel fiber. 7, 14, and 28-day non-destructive and 28-day compressive and bending tests of cementitious conductive mortars obtained from five different mixtures were performed. Two-point uniaxial method was used to determine the electrical conductivity properties of the samples. The damping ratio of the samples was obtained by performing dynamic resonance tests. Ultrasound pulse velocity (UPV) and Leeb hardness tests were performed as other non-destructive testing methods. Microstructure analysis at the interfaces of conductive concrete samples were characterized by scanning electron microscopy (SEM), EDS (Energy-Dispersive X-ray Spectroscopy), and X-ray diffraction (XRD). According to the experimental results, all data agreed and confirmed each other. When SWCNT is used in combination with steel fiber, the conductive mortar samples exhibited reasonable conductivity, while their mechanical properties turned out to below.

Nonlinear resonance suppression method of 3D contact probe based on dynamic TSVD inversion

High-precision measurement of 3D probe is usually inseparable from the quasi-static measurement model. However, insufficient dynamic characteristics and uncertainty of the measured characteristics make the measurement results inevitably affected by the resonance nonlinear factors in dynamic measurement. This paper proposes a nonlinear suppression method of dynamic resonance based on truncated singular value decomposition (TSVD) inversion. The dynamic time-domain response function based on the transfer function of the probe system is constructed, and the basic characteristics of nonlinear resonance response and the causes of error are revealed. Then, a piezoelectric positioning system is used to generate a wide-band dynamic excitation signal, and dynamic broadband response signals with linear and nonlinear comprehensive characteristics is inversed with high accuracy through the dynamic measurement experiment. By comparing with typical measurement methods, the advantages of the proposed method in improving dynamic measurement accuracy and suppressing resonance nonlinearity are quantitatively verified.

Molecular Dynamics and Nuclear Magnetic Resonance Studies of Supercritical CO2 Sorption in Poly(Methyl Methacrylate).

The study of supercritical carbon dioxide sorption processes is an important and urgent task in the field of "green" chemistry and for the selection of conditions for new polymer material formation. However, at the moment, the research of these processes is very limited, and it is necessary to select the methodology for each polymer material separately. In this paper, the principal possibility to study the powder sorption processes using 13C nuclear magnetic resonance spectroscopy, relaxation-relaxation correlation spectroscopy and molecular dynamic modeling methods will be demonstrated based on the example of polymethylmethacrylate and supercritical carbon dioxide. It was found that in the first nanoseconds and seconds during the sorption process, most of the carbon dioxide, about 75%, is sorbed into polymethylmethacrylate, while on the clock scale the remaining 25% is sorbed. The methodology presented in this paper makes it possible to select optimal conditions for technological processes associated with the production of new polymer materials based on supercritical fluids.

Vertebral and ribs enhancement in Tc-99m methylene diphosphonate bone scan image by blind deconvolution algorithm.

The objective of the study was to restore Tc-99m methylene diphosphonate (MDP) bone scan image using blind deconvolution (BD) algorithm so that ribs, vertebrae, and lesions present in them become prominent. Our study consists of retrospective data in which 356 Tc-99m MDP bone scan images (178 anterior and 178 posterior) were processed using dynamic stochastic resonance algorithm, block-matching 3D filter, and then restored using BD algorithm. Two nuclear medicine (NM) physicians compared restored image with its input image; they especially lookedfor: (a) improvement in lesions detectability, (b) artifacts if any, (c) deterioration in ribs and vertebra, and (d) contrast enhancement in adjacent vertebra and adjacent ribs. They selected one out of two (restored and input) images, which had better quality. The overall image quality was also assessed using the following image quality metrics: brightness, blur, global contrast factor, and contrast per pixel. The Wilcoxon signed-rank test was applied for finding significant difference between the value of image quality metrics of restored image and input image at level of significance alpha = 0.05. According to NM physicians, 80.3% (286 out of 356) of restored images were acceptable, whereas 19.6% (70 out of 356) were unacceptable. Ribs and vertebrae were prominent in 161 out of 178 posterior restored images. Lumbar vertebrae were enhanced and well differentiated from adjacent vertebrae in 125 out of 178 anterior restored images. The value of image quality metrics of restored and input images were found to be significantly different ( P -value < 0.0001). Ribs, vertebrae, and lesions present in them become prominent in the most of Tc-99m MDP bone scan images (80.3%) restored using BD algorithm.