A Novel Approach to Non-Destructive Rubber Vulcanization Monitoring by the Transient Radar Method.

Rubber is one of the most used materials in the world; however, raw rubber shows a relatively very low mechanical strength. Therefore, it needs to be cured before its ultimate applicatios. Curing process specifications, such as the curing time and temperature, influence the material properties of the final cured product. The transient radar method (TRM) is introduced as an alternative for vulcanization monitoring in this study. Three polyurethane-rubber samples with different curing times of 2, 4, and 5.5 min were studied by TRM to investigate the feasibility and robustness of the TRM in curing time monitoring. Additionally, the mechanical stiffness of the samples was investigated by using a unidirectional tensile test to investigate the potential correlations between curing time, dielectric permittivity, and stiffness. According to the results, the complex permittivity and stiffness of the samples with 2, 4, and 5.5 min of curing time was 17.33 ± 0.07 - (2.41 ± 0.04)j; 17.09 ± 0.05 - (4.90 ± 0.03)j; 23.60 ± 0.05 - (14.06 ± 0.06)j; and 0.29, 0.35, and 0.38 kPa, respectively. Further statistical analyses showed a correlation coefficient of 0.99 (p = 0.06), 0.80 (p = 0.40), and 0.92 (p = 0.25) between curing time-stiffness, curing time-permittivity (real part), and curing time-permittivity (imaginary part), respectively. The correlation coefficient between curing time and permittivity can show the potential of the TRM system in contact-free vulcanization monitoring, as the impact of vulcanization can be tracked by means of TRM.

Non-Invasive Intra-Abdominal Pressure Measurement by Means of Transient Radar Method: In Vitro Validation of a Novel Radar-Based Sensor.

Intra-abdominal hypertension, defined as an intra-abdominal pressure (IAP) equal to or above 12 mmHg is one of the major risk-factors for increased morbidity (organ failure) and mortality in critically ill patients. Therefore, IAP monitoring is highly recommended in intensive care unit (ICU) patients to predict development of abdominal compartment syndrome and to provide a better care for patients hospitalized in the ICU. The IAP measurement through the bladder is the actual reference standard advocated by the abdominal compartment society; however, this measurement technique is cumbersome, non-continuous, and carries a potential risk for urinary tract infections and urethral injury. Using microwave reflectometry has been proposed as one of the most promising IAP measurement alternatives. In this study, a novel radar-based method known as transient radar method (TRM) has been used to monitor the IAP in an in vitro model with an advanced abdominal wall phantom. In the second part of the study, further regression analyses have been done to calibrate the TRM system and measure the absolute value of IAP. A correlation of -0.97 with a p-value of 0.0001 was found between the IAP and the reflection response of the abdominal wall phantom. Additionally, a quadratic relation with a bias of -0.06 mmHg was found between IAP obtained from the TRM technique and the IAP values recorded by a pressure gauge. This study showed a promising future for further developing the TRM technique to use it in clinical monitoring.

Error Assessment and Mitigation Methods in Transient Radar Method.

Transient Radar Method (TRM) was recently proposed as a novel contact-free method for the characterization of multilayer dielectric structures including the geometric details. In this paper, we discuss and quantify the intrinsic and systematic errors of TRM. Also, solutions for mitigating these problems are elaborated extensively. The proposed solution for error correction will be applied to quantify experimentally the thickness of several single-layer dielectric structures with thicknesses varying from larger to smaller than the wavelength. We will show how the error correction method allows sub-wavelength thickness measurements around λ / 5 .

Pre-Clinical Validation of A Novel Continuous Intra-Abdominal Pressure Measurement Equipment (SERENNO).

Introduction: Increased intra-abdominal pressure (IAP) has an important impact on morbidity and mortality in critically ill patients. The SERENNO Sentinel system (Serenno Medical, Yokne'am Illit, Israel) is a novel device that allows automatic and continuous IAP measurements. Aims: Pre-clinical validation in a bench model study comparing the new device with the gold standard method and two other continuous IAP measurement devices. Methods: IAP measurement with the novel SERENNO device (IAPSER) was compared with the gold standard IAPH2O (water column height) and two other automatic and continuous IAP measurement devices: IAPCiM measured via the CiMON device (Pulsion Medical Systems, Munich, Germany) and IAPSPIE measured using the Spiegelberg device (Spiegelberg, Hamburg, Germany), which previously received the CE mark for clinical applications. The IAP measurement was performed six times (n = 6) at each pressure value (between 0 and 35 mmHg) with different methods and the height of the water column in a bench-top phantom was used as the reference IAP for further interpretations. In addition to the quadruple comparisons, intra- and inter-observer variability of IAP measurements were also calculated. Correlation studies and Bland and Altman's analyses were performed in addition to the concordance study. Results: The CiMON and Spiegelberg devices showed a greater dynamic range and standard deviation when recording IAPCiM and IAPSPIE compared with IAPSER. In general, the maximum and minimum values of IAP recorded with each device (at each level of IAPH2O) were significantly different from each other. However, the average values were in very good agreement. The highest correlation was observed between IAPSER and IAPH2O, and IAPSER and IAPSPIE (R = 0.99, p = 0.001 for both comparisons and intra- and inter-observer measurements). Although the CiMON and SERENNO systems were in very good agreement with each other, a slightly smaller correlation coefficient was found between them (R = 0.95, p = 0.001, and R = 0.96, p = 0.001 for intra- and inter-observer measurements, respectively). When compared to the gold standard (IAPH2O), Bland and Altman's analysis showed a mean difference of +0.44, -0.25, and -0.04 mmHg for the intra-observer measurements and +0.18, -0.75, and -0.58 mmHg for the inter-observer measurements for IAPSER, IAPCiM, and IAPSPIE, respectively. IAPSER showed a small positive bias (overestimation), while IAPCiM and IAPSPIE showed a negative bias (underestimation) when compared to IAPH2O. Further statistical analysis showed a concordance coefficient of 100% with an excellent ability of the SERENNO system in tracking IAPH2O changes. Conclusions: Pre-clinical validation of a new IAP monitoring device (SERENNO) showed very promising results when compared with the gold standard and other continuous techniques; however, clinical trials should be followed as the next stage of the validation process. Based on the actual research guidelines, the SERENNO system can be used interchangeably with the gold standard.

Selective changes in locomotor activity in mice due to low-intensity microwaves amplitude modulated in the EEG spectral domain.

Despite the numerous benefits of microwave applications in our daily life, microwaves were associated with diverse neurological complaints such as headaches and impaired sleep patterns, and changes in the electroencephalogram (EEG). To which extent microwaves influence the brain function remains unclear. This exploratory study assessed the behavior and neurochemistry in mice immediately or 4weeks after a 6-day exposure to low-intensity 10-GHz microwaves with an amplitude modulation (AM) of 2 or 8Hz. These modulation frequencies of 2 and 8Hz are situated within the delta and theta-alpha frequency bands in the EEG spectrum and are associated with sleep and active behavior, respectively. During these experiments, the specific absorbance rate was 0.3W/kg increasing the brain temperature with 0.23°C. For the first time, exposing mice to 8-Hz AM significantly reduced locomotor activity in an open field immediately after exposure which normalized after 4weeks. This in contrast to 2-Hz AM which didn't induce significant changes in locomotor activity immediately and 4weeks after exposure. Despite this difference in motor behavior, no significant changes in striatal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels and DOPAC/DA turnover nor in cortical glutamate (GLU) concentrations were detected. In all cases, no effects on motor coordination on a rotarod, spatial working memory, anxiety nor depressive-like behavior were observed. The outcome of this study indicates that exposing mice to low-intensity 8-Hz AM microwaves can alter the locomotor activity in contrast to 2-Hz AM which did not affect the tested behaviors.