RESUMO
Thermal processing is commonly employed to ensure the quality and extend the shelf-life of fruits and vegetables. Radio frequency (RF) heating has been used as a promising alternative treatment to replace conventional thermal processing methods with advantages of rapid, volumetric, and deep penetration heating characteristics. This article provides comprehensive information regarding RF heating uniformity and applications in processing of fruit and vegetable products, including disinfestation, blanching, drying, and pasteurization. The dielectric properties of fruits and vegetables and their products have also been summarized. In addition, recommendations for future research on RF heating are proposed to enhance practical applications for fruits and vegetables processing in future.
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Manipulação de Alimentos , Frutas , Ondas de Rádio , Verduras , Frutas/química , Verduras/química , Manipulação de Alimentos/métodos , Pasteurização/métodos , Temperatura AltaRESUMO
The deployment of 5 G wireless technology has generated considerable interest and debate regarding its potential effects on human health. This work provides a comprehensive overview of the current scientific understanding of the potential health implications associated with 5 G technology. Drawing upon a wide range of research studies, reviews, and expert opinions, we explore the implications through which 5 G signals interact with the human body. This work presents a balanced perspective, summarizing both the potential benefits of 5 G technology, such as improved data transfer speeds, reduced latency, and enhanced connectivity, as well as concerns that have been raised about its effects on human's tissues. We discuss various aspects of health impacts, including thermal and nonthermal effects, focusing on the existing research on radiofrequency electromagnetic fields and their potential to cause adverse health outcomes. Simulation results show the negative effect of radio waves on human's tissues.
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Campos Eletromagnéticos , Ondas de Rádio , Humanos , Ondas de Rádio/efeitos adversos , Campos Eletromagnéticos/efeitos adversos , Tecnologia sem FioRESUMO
The influence of weak radio-frequency electromagnetic field (RF-EMF) on living organisms raises new concern because of the Industrial, Scientific, and Medical (ISM) frequency band at 6.78 MHz being promoted by the AirFuel Alliance for mid-range wireless power transfer (WPT) applications and product development. Human exposure to the RF-EMF radiation is unavoidable. In this study, we employed in vitro cell culture and molecular biology approach coupled with integrated transcriptomic and proteomic analyses to uncover the effects of RF-EMF on cells at molecular and cellular levels. Our study has demonstrated that weak RF-EMF is sufficient to exert non-thermal effects on human umbilical vein endothelial cells (HUVEC). Exposure of weak RF-EMF promotes cell proliferation, inhibits apoptosis and deregulates ROS balance. Alteration of several signaling pathways and key enzymes involved in NADPH metabolism, cell proliferation and ferroptosis were identified. Our current study provide solid evidence for the first time that the present safety standards that solely considered the thermal effect of RF-EMF on cell tissue are inadequate, prompt response and modification of existing Guidelines, Standards and Regulation are warranted.
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Apoptose , Proliferação de Células , Campos Eletromagnéticos , Células Endoteliais da Veia Umbilical Humana , NADP , Ondas de Rádio , Espécies Reativas de Oxigênio , Humanos , Espécies Reativas de Oxigênio/metabolismo , NADP/metabolismo , Ondas de Rádio/efeitos adversos , Campos Eletromagnéticos/efeitos adversos , Transdução de SinaisRESUMO
The magnetic compass sense of migratory songbirds is thought to derive from magnetically sensitive photochemical reactions in cryptochromes located in photoreceptor cells in the birds' retinas. More specifically, transient radical pairs formed by light-activation of these proteins have been proposed to account for the birds' ability to orient themselves using the Earth's magnetic field and for the observation that radiofrequency magnetic fields, superimposed on the Earth's magnetic field, can disrupt this ability. Here, by means of spin dynamics simulations, we show that it may be possible for the birds to orient in a monochromatic radiofrequency field in the absence of the Earth's magnetic field. If such a behavioural test were successful, it would provide powerful additional evidence for a radical pair mechanism of avian magnetoreception.
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Campos Magnéticos , Animais , Criptocromos/metabolismo , Ondas de Rádio , Planeta Terra , Aves Canoras/fisiologia , Modelos Biológicos , Orientação/fisiologia , Migração Animal/fisiologiaRESUMO
Cognitive radio networks (CRN) enable wireless devices to sense the radio spectrum, determine the frequency state channels, and reconfigure the communication variables to satisfy Quality of Service (QoS) needs by reducing energy utilization. In CRN, spectrum sensing is an essential process that is highly challenging and can be addressed by several traditional techniques, such as energy detection, match filtering, etc. For now, the current models' performance is impacted by the comparatively low Signal to Noise Ratio (SNR) of recognized signals and the insignificant quantity of traditional signal samples. This research proposals a new spectral sensing technique for cognitive radio networks (SST-CRN) that addresses the drawbacks of predictable energy detection models. With the use of a deep belief network (DBN), the suggested model contributes to accomplish a nonlinear threshold based on the chicken swarm algorithm (CSA). The proposed DBN enabled SST-CRN technique goes through two phases in a organized process: offline and online. Throughout the offline phase, the DBN model is methodically trained on pre-gathered data, developing the aptitude to identify problematic patterns and examples from the spectral features of the radio environment. This stage involves extensive feature extraction, validation, and model development to ensure that the DBN can professionally represent complicated spectral dynamics. Additionally, online spectrum sensing is conducted during the real communication phase to enable real-time adaptation to dynamic changes in the spectrum environment. Offline spectrum sensing is typically performed during a devoted sensing period before actual communication begins. When combined with DBN's deep learning capabilities and CSO's innate nature-inspired algorithms, a synergistic framework is created that enables CRNs to explore and allocate incidences on their own with astonishing accuracy. The proposed solution considerably improves the spectrum efficiency and resilience of CRNs by harnessing the power of DBN, which leads to more effective resource utilization and less interference. The Simulation results show that our proposed strategy produces more accurate spectrum occupancy assessments. The result parameters such as probability of detection, SNR of -24dB, the SST-CRN perfect has increased a developed Pd of 0.810, whereas the existing methods RMLSSCRN-100 and RMLSSCRN-300 have accomplished a lower Pd of 0.577 and 0.736, respectively. Our deep learning methodology uses convolutional neural networks to automatically learn and adapt to dynamic and complicated radio environments, improving accuracy and flexibility over classic spectrum sensing approaches. Future research might focus on improving CSO algorithms to better optimize the spectrum sensing process, enhancing the reliability of DBN-enabled sensing techniques.
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Algoritmos , Galinhas , Animais , Tecnologia sem Fio , Redes de Comunicação de Computadores , Aprendizado Profundo , Ondas de Rádio , Razão Sinal-Ruído , Cognição/fisiologia , Modelos Teóricos , Redes Neurais de ComputaçãoRESUMO
This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield's cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield's theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NFbirdcage-NFslotcage= 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage= 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.
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Desenho de Equipamento , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Ondas de Rádio , Animais , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/instrumentação , Ratos , Simulação por Computador , Campos Eletromagnéticos , Análise de Elementos Finitos , Campos Magnéticos , Imagem Corporal Total/métodos , Imagem Corporal Total/instrumentaçãoRESUMO
Simultaneous positron emission tomography (PET)/magnetic resonance imaging provides concurrent information about anatomic, functional, and molecular changes in disease. We are developing a second generation MR-compatible RF-penetrable TOF-PET insert. The insert has a smaller scintillation crystal size and ring diameter compared to clinical whole-body PET scanners, resulting in higher spatial resolution and sensitivity. This paper reports the initial system performance of this full-ring PET insert. The global photopeak energy resolution and global coincidence time resolution, 11.74 ± 0.03 % FWHM and 238.1 ± 0.5 ps FWHM, respectively, are preserved as we scaled up the system to a full ring comprising 12, 288 LYSO-SiPM channels (crystal size: 3.2 × 3.2 × 20 mm3). Throughout a ten-hour experiment, the system performance remained stable, exhibiting a less than 1% change in all measured parameters. In a resolution phantom study, the system successfully resolved all 2.8 mm diameter rods, achieving an average VPR of 0.28 ± 0.08 without TOF and 0.24 ± 0.07 with TOF applied. Moreover, the implementation of TOF in the Hoffman phantom study also enhanced image quality. Initial MR compatibility studies of the full PET ring were performed with it unpowered as a milestone to focus on looking for material and geometry-related artifacts. During all MR studies, the MR body coil functioned as both the transmit and receive coil, and no observable artifacts were detected. As expected, using the body coil also as the RF receiver, MR image signal-to-noise ratio exhibited degradation (â¼30%), so we are developing a high quality receive-only coil that resides inside the PET ring.
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Encéfalo , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Tomografia por Emissão de Pósitrons , Tomografia por Emissão de Pósitrons/instrumentação , Imageamento por Ressonância Magnética/instrumentação , Encéfalo/diagnóstico por imagem , Ondas de Rádio , Imagem Multimodal/instrumentação , Fatores de Tempo , Processamento de Imagem Assistida por Computador/métodos , HumanosRESUMO
Background: While drainage/removal of fluid and toxins from the brain by cerebrospinal fluid (CSF) directly into venous blood is well-known, a second drainage route has recently been (re)discovered-meningeal lymphatic vessels (mLVs)-which are responsible for up to half of total brain fluid/toxin drainage. The cytokine vascular endothelial growth factor (VEGF) increases mLV diameter and numbers to increase mLV drainage, resulting in increased mLV drainage. Alzheimer's disease (AD) is characterized by low plasma and CSF levels of VEGF. Objective: To determine if non-invasive transcranial radiofrequency wave treatment (TRFT), through modulation of VEGF levels in blood and CSF, can affect removal of toxins tau and amyloid-ß (Aß) from the brain. Methods: Eight mild/moderate AD subjects were given twice-daily 1-hour TRFT sessions at home by their caregivers. Blood and CSF samples were taken at baseline and following completion of 2 months of TRFT. Results: In plasma and/or CSF, strong baseline correlations between VEGF levels and AD markers (t-tau, p-tau, Aß1-40, Aß1-42) were eliminated by TRFT. This effect was primarily due to TRFT-induced increases in VEGF levels in AD subjects with low or unmeasurable "baseline" VEGF levels. These increased VEGF levels were associated with increased clearance/drainage of tau and Aß from the brain, likely through VEGF's actions on mLVs. Conclusions: A new mechanism of TRFT is identified (facilitation of brain tau and Aß clearance via VEGF) that is likely contributory to TRFT's reversal of cognitive impairment in AD subjects. TRFT may be particularly effective for cognitive benefit in AD subjects who have low VEGF levels.
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Doença de Alzheimer , Peptídeos beta-Amiloides , Encéfalo , Fator A de Crescimento do Endotélio Vascular , Proteínas tau , Humanos , Doença de Alzheimer/terapia , Doença de Alzheimer/metabolismo , Proteínas tau/líquido cefalorraquidiano , Proteínas tau/metabolismo , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/líquido cefalorraquidiano , Masculino , Feminino , Idoso , Encéfalo/metabolismo , Idoso de 80 Anos ou mais , Pessoa de Meia-Idade , Fragmentos de Peptídeos/líquido cefalorraquidiano , Ondas de RádioRESUMO
BACKGROUND: Bipolar microneedling radiofrequency (RF) treatment generates different patterns of thermal reactions, depending on the skin impedance and RF treatment parameters, including the frequency, power, conduction time, settings of sub-pulse packs, and penetrating depth and type of microneedles used. We compared the effect of sequential delivery of 1- and 2-MHz bipolar RF energy to in vivo minipig skin on thermal tissue reaction. METHODS: RF treatments at frequencies of 1 and 2 MHz were sequentially delivered to minipigs' skin in vivo. A histological study was performed to analyze RF-induced skin reactions at 1-h and at 3-, 7-, and 14-days post-treatment. RESULTS: The skin specimens demonstrated that the two different frequencies of RF treatment generated mixed patterns of the peri-electrode coagulative necrosis (PECN) according to the experimental settings and tissue impedance. In the PECN zone, the tissue coagulation induced by the first RF treatment was surrounded by the effect of the later RF treatment at the other RF frequency. In the inter-electrode non-necrotic thermal reaction zone, the effect of the latter RF treatment was widespread and deep through the dermis, which had received RF treatment at the other frequency first. The delivery of pulsed-type RF energy at sub-pulse packs of 6 or 10 provided effective RF delivery over long conduction time without excessive thermal damage of the epidermis. Nonetheless, by sequential delivery of two different RF frequencies, RF-induced tissue reactions were found to be markedly enhanced. CONCLUSION: The sequential delivery of 1- and 2-MHz RF energy induces novel histological patterns of tissue reactions, which can synergistically enhance the thermostimulatory effects of each RF setting. Moreover, variations in patterns of tissue reactions can be generated by regulating the order of frequencies and the number of sub-pulse packs of RF used.
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Agulhas , Pele , Porco Miniatura , Animais , Suínos , Pele/efeitos da radiação , Pele/patologia , Necrose , Ondas de Rádio , Terapia por Radiofrequência/métodos , Terapia por Radiofrequência/instrumentação , Indução Percutânea de ColágenoRESUMO
Background: The widespread use of radiofrequency (RF) sources, ranging from household appliances to telecommunications devices and military equipment, raises concerns among people and regulatory agencies about the potential health risks of RF exposure. Consequently, several in vitro and in vivo studies have been done to investigate the biological effects, in particular non-thermal, of this non-ionizing radiation. To date, this issue is still being debated due to the controversial results that have been reported. Furthermore, the impact of different RF signal modulations on biological systems remains poorly investigated. The present in vitro study aims to evaluate the cytotoxicity and genotoxicity of continuous or pulsed 1.6 GHz RF in human dermal fibroblasts (HDF). Methods: HDF cultures were exposed to continuous and pulsed 1.6 GHz RF, for 2 h, with Specific Absorption Rate (SAR) of 0.4 W/kg. The potential biological effects of 1.6 GHz RF on HDF were assessed with a multi-methodological approach, analyzing the effects on cell cycle, ultrastructure, protein expression, mitotic spindle, CREST stained micronuclei, chromosome segregation and γ-H2AX/53BP1 foci. Results: 1.6 GHz RF exposure modified proteins expression and morphology of HDF. Specifically, the expression of different heat-shock proteins (HSP) (i.e., HSP-90, HSP-60, and HSP-25) and phospho-AKT were affected. In addition, both continuous and pulsed RF modified the cytoskeletal organization in HDF and increased the number of lysosomes, while the formation of autophagosomes was observed only after pulsed RF exposure. Mitotic spindle anomalies were also found after exposure. However, no significant effect was observed on cell cycle, chromosome segregation, CREST-stained micronuclei and γ-H2AX/53BP1 foci. Conclusion: The results of the present study show the absence of genotoxic damage in 1.6 GHz RF exposed HDF and, although mitotic spindle alterations were observed, they did not have an aneugenic effect. On the other hand, changes in some proteins expression and cell ultrastructure in exposed HDF suggest that RF can potentially induce cell alterations at the morphological and molecular levels.
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Fibroblastos , Ondas de Rádio , Humanos , Fibroblastos/efeitos da radiação , Ondas de Rádio/efeitos adversos , Dano ao DNA , Ciclo Celular/efeitos da radiação , Células CultivadasRESUMO
The objective were to evaluate the effects of supplementation of standardized dry extract of Rosmarinus officinalis (RO) and the application of aesthetic radiofrequency on the oxidative stress markers catalase (CAT), superoxide dismutase (SOD), non-protein thiols (NP-SH), and thiobarbituric acid reactive species (TBARS) and the biochemical markers triglycerides, total cholesterol, high density lipoprotein (HDL) cholesterol, glutamic-oxaloacetic transaminase (TGO/AST), pyruvic-glutamic transaminase (TGP/ALT), gamma glutamyl transpeptidase (gamma-GT), and creatinine. This study included 32 women received the aesthetic therapy to reduce localized fat. They were divided into the control group (n = 8) receiving placebo capsules and the intervention group (n = 24) subdivided into Group A, B, and C, each with eight members receiving supplementation with 100, 500, and 1000â mg/day of standardized dry extract of RO, respectively. The Universal Trial Number (UTN) - U1111-1274-6255. Supplementation with RO (500â mg/day) demonstrated a reduction in oxidative stress (quantified with through a significant increase in NP-SH and a reduction in SOD and CAT enzymes). The radiofrequency aesthetic treatment did not promote an increase in oxidative stress; however, it caused significant changes in total cholesterol, HDL cholesterol, and creatinine. RO is a plant with antioxidant effects and its oral consumption is safe in selected women subjects in hepatic and renal markers.
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Suplementos Nutricionais , Estresse Oxidativo , Extratos Vegetais , Rosmarinus , Humanos , Feminino , Estresse Oxidativo/efeitos dos fármacos , Método Duplo-Cego , Rosmarinus/química , Adulto , Extratos Vegetais/farmacologia , Ondas de Rádio , Superóxido Dismutase/metabolismo , Superóxido Dismutase/sangue , Pessoa de Meia-Idade , Biomarcadores/sangue , Antioxidantes/farmacologia , Catalase/metabolismo , Catalase/sangue , Adulto JovemRESUMO
In this systematic review, the potential role of in vivo RF-EMF exposure combined with the administration of well-known carcinogens in tumor promotion/progression is assessed. A total of 25 papers were included in the review. Each paper was assessed for Risk of Bias and for the attribution of the quality category. A meta-analysis was conducted on 18 studies, analyzing data for nine different organs/tumors to assess the potential increased risk for the onset of tumors as well as the effects on survival. A descriptive review was performed for the remaining seven eligible papers. In most cases, the results of the meta-analysis did not reveal a statistically significant difference in tumor onset between the sham and co-exposed samples. There was a numerically small increase in the risk of malignant tumors observed in the kidney and liver, as well as benign lung tumors. The level of evidence for health effects indicated "inadequate" evidence for an association between in vivo co-exposure to RF-EMF and known carcinogens and the onset of malignant or benign tumors in most of the analyzed tissues. Nevertheless, the limited number of eligible papers/studies for most of the analyzed tissues suggests that these results cannot be considered definitively conclusive.
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Campos Eletromagnéticos , Ondas de Rádio , Humanos , Ondas de Rádio/efeitos adversos , Campos Eletromagnéticos/efeitos adversos , Animais , Carcinogênese/efeitos da radiação , Carcinógenos/toxicidade , Neoplasias/etiologiaRESUMO
The widespread use of wireless communication devices has necessitated unavoidable exposure to radiofrequency electromagnetic fields (RF-EMF). In particular, increasing RF-EMF exposure among children is primarily driven by mobile phone use. Therefore, this study investigated the effects of 1850 MHz RF-EMF exposure at a specific absorption rate of 4.0 W/kg on cortical neurons in mice at postnatal day 28. The results indicated a significant reduction in the number of mushroom-shaped dendritic spines in the prefrontal cortex after daily exposure for 4 weeks. Additionally, prolonged RF-EMF exposure over 9 days led to a gradual decrease in postsynaptic density 95 puncta and inhibited neurite outgrowth in developing cortical neurons. Moreover, the expression levels of genes associated with synapse formation, such as synaptic cell adhesion molecules and cyclin-dependent kinase 5, were reduced in the cerebral cortexes of RF-EMF-exposed mice. Behavioral assessments using the Morris water maze revealed altered spatial learning and memory after the 4-week exposure period. These findings underscore the potential of RF-EMF exposure during childhood to disrupt synaptic function in the cerebral cortex, thereby affecting the developmental stages of the nervous system and potentially influencing later cognitive function.
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Neurônios , Ondas de Rádio , Sinapses , Animais , Camundongos , Sinapses/efeitos da radiação , Sinapses/metabolismo , Neurônios/efeitos da radiação , Neurônios/metabolismo , Ondas de Rádio/efeitos adversos , Campos Eletromagnéticos/efeitos adversos , Córtex Cerebral/efeitos da radiação , Córtex Cerebral/metabolismo , Espinhas Dendríticas/efeitos da radiação , Espinhas Dendríticas/metabolismo , Memória/efeitos da radiação , Aprendizagem em Labirinto/efeitos da radiação , Masculino , Quinase 5 Dependente de Ciclina/metabolismo , Quinase 5 Dependente de Ciclina/genética , Crescimento Neuronal/efeitos da radiação , Aprendizagem/efeitos da radiação , Córtex Pré-Frontal/efeitos da radiação , Córtex Pré-Frontal/metabolismo , Proteína 4 Homóloga a Disks-Large/metabolismoRESUMO
Magnetic Resonance Imaging (MRI) employs a radiofrequency electromagnetic field to create pictures on a computer. The prospective biological consequences of exposure to radiofrequency electromagnetic fields (RF EMFs) have not yet been demonstrated, and there is not enough evidence on biological hazards to offer a definite response concerning possible RF health dangers. Therefore, it is crucial to research the health concerns in reaction to RF EMFs, considering the entire exposure in terms of patients receiving MRI. Monitoring increases in temperaturein-vivothroughout MRI scan is extremely invasive and has resulted in a rise in the utilization of computational methods to estimate distributions of temperatures. The purpose of this study is to estimate the absorbed power of the brain exposed to RF in patients undergoing brain MRI scan. A three-dimensional Penne's bio-heat equation was modified to computationally analyze the temperature distributions and potential thermal effects within the brain during MRI scans in the 0.3 T to 1.5 T range (12.77 MHz to 63.87 MHz). The instantaneous temperature distributions of thein-vivotissue in the brain temperatures measured at a time, t = 20.62 s is 0.2 °C and t = 30.92 s is 0.4 °C, while the highest temperatures recorded at 1.03 min and 2.06 min were 0.4 °C and 0.6 °C accordingly. From the temperature distributions of thein-vivotissue in the brain temperatures measured, there is heat build-up in patients who are exposed to electromagnetic frequency ranges, and, consequently, temperature increases within patients are difficult to prevent. The study has, however, indicated that lengthier imaging duration appears to be related to increasing body temperature.
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Encéfalo , Simulação por Computador , Campos Eletromagnéticos , Imageamento por Ressonância Magnética , Ondas de Rádio , Radiometria , Imageamento por Ressonância Magnética/métodos , Humanos , Encéfalo/diagnóstico por imagem , Encéfalo/efeitos da radiação , Radiometria/métodos , Temperatura , Imagens de FantasmasRESUMO
Investigations of human brain disorders are frequently conducted in rodent models using magnetic resonance imaging. Due to the small specimen size and the increase in signal-to-noise ratio with the static magnetic field strength, dedicated small-bore animal scanners can be used to acquire high-resolution data. Ultra-high-field (≥7 T) whole-body human scanners are increasingly available, and they can also be used for animal investigations. Dedicated sensors, in this case, radiofrequency coils, are required to achieve sufficient sensitivity for the high spatial resolution needed for imaging small anatomical structures. In this work, a four-channel transceiver coil array for rat brain imaging at 7 T is presented, which can be adjusted for use on a wide range of differently sized rats, from infants to large adults. Three suitable array designs (with two to four elements covering the whole rat brain) were compared using full-wave 3D electromagnetic simulation. An optimized static B1+ shim was derived to maximize B1+ in the rat brain for both small and big rats. The design, together with a 3D-printed adjustable coil housing, was tested and validated in ex vivo rat bench and MRI measurements.
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Encéfalo , Imageamento por Ressonância Magnética , Animais , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Ratos , Encéfalo/diagnóstico por imagem , Razão Sinal-Ruído , Ondas de Rádio , Desenho de Equipamento , Humanos , Imagens de FantasmasRESUMO
In the field of ultra-high field MR imaging, the challenges associated with higher frequencies and shorter wavelengths necessitate rigorous attention to multichannel array design. While the need for such arrays remains, and efforts to increase channel counts continue, a persistent impediment-inter-element coupling-constantly hinders development. This coupling degrades current and field distribution, introduces noise correlation between channels, and alters the frequency of array elements, affecting image quality and overall performance. The goal of optimizing ultra-high field MRI goes beyond resolving inter-element coupling and includes significant safety considerations related to the design changes required to achieve high-impedance coils. Although these coils provide excellent isolation, the higher impedance needs special design changes. However, such changes pose a significant safety risk in the form of strong electric fields across low-capacitance lumped components. This process may raise Specific Absorption Rate (SAR) values in the imaging subject, increasing power deposition and, as a result, the risk of tissue heating-related injury. To balance the requirement of inter-element decoupling with the critical need for safety, we suggest a new solution. Our method uses high-dielectric materials to efficiently reduce electric fields and SAR values in the imaging sample. This intervention tries to maintain B1 efficiency and inter-element decoupling within the existing array design, which includes high-impedance coils. Our method aims to promote the full potential of ultra-high field MRI by alleviating this critical safety concern with minimal changes to the existing array setup.
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Impedância Elétrica , Imageamento por Ressonância Magnética , Imageamento por Ressonância Magnética/métodos , Humanos , Ondas de Rádio , Imagens de Fantasmas , Desenho de EquipamentoRESUMO
To obtain high-quality cherry products, ultrasound (US) combined with five chemical pretreatment techniques were used on cherry prior to radio frequency vacuum drying (RFV), including carboxymethyl cellulose coating (CMC), cellulase (CE), ethanol (EA), isomaltooligosaccharide (IMO), and potassium carbonate + ethyl oleate (PC + AEEO). The effect of different pretreatments (US-CMC, US-CE, US-EA, US-IMO, US-(PC + AEEO)) on the drying characteristics, quality properties, texture, and sensory evaluation of cherries was evaluated. Results showed that the dehydration time and energy consumption were decreased by 4.17 - 20.83 % and 3.22 - 19.34 %, respectively, and the contents of individual sugars, soluble solid, total phenolics (TPC), natural active substances, total flavonoids (TFC), and antioxidant properties (DPPH, ABTS and FRAP) were significantly increased after US combined with five chemical treatments (P < 0.05). Moreover, the pretreatment played important role in improving texture properties and surface color retention in the dried cherries. According to the sensory evaluation analysis, the dehydrated cherries pretreated with US-CMC exhibited the highest overall acceptance, texture, crispness, color, and sweet taste showed lower off-odor, bitter taste and sour taste compared to control and other pretreatments. The findings indicate that US-CMC pretreatment is a promising technique for increasing physicochemical qualities and dehydration rate of samples, which provides a novel strategy to processing of dried cherry.
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Dessecação , Prunus avium , Vácuo , Dessecação/métodos , Prunus avium/química , Ondas Ultrassônicas , Antioxidantes/química , Ondas de Rádio , Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Paladar , Fenóis/análise , Fenóis/químicaRESUMO
Some of the difficulties in numerical modeling of wireless communication devices for dosimetric evaluations arise from, e.g. incomplete documentation available for the numerical model, such as missing information on dielectric materials or the antenna matching circuitry. This study investigates the impact of these difficulties on the dosimetric results, such as the peak spatial average specific absorption rate at 900 and 1800 MHz and the peak spatial average power density at 28 GHz. The impact of dielectric losses, detuning, and mesh resolution is quantified using different generic and Computer Aided Design (CAD) based models of wireless transmitters. The findings show that the uncertainties of the numerical results due to detuning and mesh resolution can be reduced by normalization to the antenna feedpoint power instead of the feedpoint current. Uncertainties due to variations in dielectric losses can largely be compensated by normalization to the radiated power.
Assuntos
Tecnologia sem Fio , Incerteza , Simulação por Computador , Modelos Teóricos , Humanos , Desenho Assistido por Computador , Radiometria/métodos , Desenho de Equipamento , Ondas de RádioRESUMO
Tiger nut (TN) is a valuable nutrient and gluten-free tuber. To achieve high-quality TN flour as functional ingredients in food, it is essential to develop effective drying technologies for TN. Five drying methods including natural drying (Control), hot-air drying (HD), radio frequency single drying (RFSD), RF assisted hot-air drying (RFHD), and RF- vacuum drying (RFVD) were selected and compared to determine their effects on physiochemical, structural, and rheological properties of TN flour. Results showed that RF drying (RFD) significantly improved the hydration, oil-absorbing, and antioxidant activity capacity, especially for RFVD. RFHD exhibited greater color (BI = 13.80 ± 0.05 and C = 10.26 ± 0.05) and reducing sugar content (253.50 ± 2.27 mg d.b.) than RFSD and RFVD. The gelatinization temperature, enthalpy value, and particle size (57.30-269.33 µm) of TN flour were reduced. The structural property results indicated that RFD reduced the relative crystallinity and short-range ordering of the flour, altered protein secondary structure, and caused the damaged microstructure in comparison with Control and HD groups. All sample gels exhibited a weak strain overshoot behavior (type III) under large amplitude oscillations, and RFD resulted in a reduced viscoelastic behavior. RFD could be an effective method to produce functional TN flour.
Assuntos
Dessecação , Farinha , Reologia , Farinha/análise , Dessecação/métodos , Antioxidantes/química , Fenômenos Químicos , Ondas de Rádio , Nozes/química , ViscosidadeRESUMO
Androgenic alopecia (AGA) is the most common type of alopecia and its treatments involve drugs that have various adverse effects and are not completely effective. Radiofrequency-based therapies (RF) are an alternative for AGA treatment. Although there is increasing clinical evidence of the effectiveness of RF for alopecia, its effects at the tissue and cellular level have not been studied in detail. The objective of this study was to analyze ex vivo the potential effect of RF currents used in capacitive resistive electrical transfer (CRET) therapy on AGA. Hair follicles (HFs) were donated by patients with AGA and treated with CRET. AGA-HFs were exposed in vitro to intermittent 448 kHz electric current in subthermal conditions. Cell proliferation (Ki67), apoptosis (TUNEL assay), differentiation (ß-catenin), integrity (collagen and MMP9), thickness of the epidermis surrounding HF, proportion of bulge cells and melanoblasts in AGA-HF were analyzed by immunohistochemistry. CRET increased proliferation and decreased death of different populations of AGA-HF cells. In addition, the melanoblasts increased in bulge and the epidermis surrounding the hair follicle thickened. These results support the effectiveness of RF-based therapies for the treatment of alopecia. However, clinical trials are necessary to know the true effectiveness of CRET therapy and other RF therapies for AGA treatment.