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Gamma irradiation has emerged as a promising technique for tailoring the microstructures and, by extension, properties of nanoparticles embedded polymer composites. Despite extensive efforts to elucidate the gamma ray-induced changes in nanocomposites, there is still a notable lack of studies on the effects of low-doses on the properties of polymer nanocomposites. This leads to a quantitative investigation about the impact of low-dose gamma irradiation on the optical properties of graphite nanoflake (GnF)-reinforced polydimethylsiloxane (PDMS) nanocomposites (GnF/PDMS nanocomposites). A series of GnF/PDMS nanocomposites with different GnF concentrations ranging from 1 to 10 wt% was prepared, followed by gamma irradiation at specific doses ranging from 0.0 to 5.0 kGy. The analyses showed that even low-dose gamma irradiation causes microstructural changes in the nanocomposites, resulting in a proportional relation between their light absorption properties and gamma ray dose. In detail, the GnF/PDMS nanocomposites showed a gradual increase in light absorption, peaking at gamma irradiation dose of 5 kGy. For example, 4 wt% GnF/PDMS nanocomposite under the influence of 5 kGy gamma irradiation shows an average light absorption value of 96.3%, whereas nonirradiated sample at the same composites exhibits absorption value of 93.2%. The increase in absorption is attributed to the combined effects arising from microstructural alterations in the nanocomposites, including the improved dispersion of GnF and the restoration of carbon rings under gamma irradiation. Notably, the optical energy band gap of the nanocomposite samples reveals a decreasing trend with increasing gamma irradiation. Specifically, band gap for 4 wt% GnF/PDMS at 5 kGy radiation is 2.76 eV against 4.96 eV for non-irradiated pure PDMS. This study sheds light on the fundamentals of enhancing the light absorption characteristics of GnF/PDMS nanocomposites under low-dose gamma irradiation. [ABSTRACT FROM AUTHOR]

Three-dimensional computational fluid dynamics (CFD) modeling of the hydrodynamic characteristics for the various sand particle sizes (10 μm, 250 μm, 482 μm, 750 μm, 1000 μm, and the actual particle size distribution (PSD)) in a 0.1 MWth pilot-scale full-loop circulating fluidized bed combustor (CFBC) was numerically investigated with a commercial CFD code, ANSYS FLUENT. Those were clearly validated with actual CFBC operating data. As the result, the sand particle size of the actual PSD was in good agreement. In order to accurately simulate wood pellet combustion, kinetic parameters for activation energy (Ea) and pre-exponential factor (A) for wood pellet decomposition and char combustion were obtained from lab-scale TGA experiments with wood pellet sample actually used for CFBC operation. The CFD modeling on wood pellet combustion were conducted with the selected sand particle size of actual PSD with improved char combustion model using the user-defined function (UDF) reflected kinetic parameters. The CFD modeling results were carefully compared with actual CFBC operating results. Therefore, our CFD simulation results for the concentrations of gas species (N2, CO2, O2, SO2, CO, NO, and N2O) at the gas exit in the cyclone were also in good agreement with the actual CFBC operating data. The accuracy improvements were increased from 1.9 times to 2.5 times due to our improved char combustion model using the UDF. [ABSTRACT FROM AUTHOR]

Both the uterus and breasts have sex hormone dependence, yet there are few studies on the association between breast disease and uterine fibroids (UFs). The purpose of this study was to investigate the incidence of benign breast disease (BBD), carcinoma in situ (CIS), and breast cancer (BC) in women treated for UFs compared to women who were not treated for UFs. This retrospective cohort study used national health insurance data from January 1st, 2011, to December 31st, 2020. We selected women between 20 and 50 years old who (1) were treated for UFs (UF group) or (2) visited medical institutions for personal health screening tests without UFs (control group). We analyzed independent variables such as age, socioeconomic status (SES), region, Charlson comorbidity index (CCI), delivery status, menopausal status, menopausal hormone therapy (MHT), endometriosis, hypertension (HTN), diabetes mellitus (DM), and dyslipidemia based on the first date of uterine myomectomy in the UF group and the first visiting date for health screening in the non-UF group. There were 190,583 and 439,940 participants in the UF and control groups, respectively. Compared with those of the control group, the RRs of BBD, CIS, and BC were increased in the UF group. The hazard ratios (HRs) of BBD, CIS, and BC in the UF group were 1.335 (95% confidence interval (CI) 1.299–1.372), 1.796 (95% CI 1.542–2.092), and 1.3 (95% CI 1.198–1.41), respectively. When we analyzed the risk of BC according to age at inclusion, UFs group had the increased risk of BCs in all age groups in comparison with control group. Women with low SES (HR 0.514, 95% CI 0.36–0.734) and living in rural areas (HR 0.889, 95% CI 0.822–0.962) had a lower risk of BC. Our study showed that women with UFs had a higher risk of BBD, CIS, and BC than those without UFs. This result suggests that women with UFs should be more conscious of BC than those without UFs. Therefore, doctors should consider recommending regular breast self-exams, mammography, or ultrasound for the early detection of BC in women with UFs. [ABSTRACT FROM AUTHOR]

There is an ever-increasing demand for polymer-based electrical leads patterned on polymer substrates of any shape to connect two electrical components. Much, however, still remains challenging about electrical leads made of polymer nanocomposites that have high affinity to polymer substrates and outstanding applicability to curved surfaces, unlike metals. This leads to the need for the development of photopatternable and electrically conductive polymer nanocomposites and, by extension, comprehensive understanding of the constituent and processes involved in their development. Here, a set of polymer nanocomposites incorporating exfoliated graphite nanoplatelet (xGnP) into SU-8, xGnP/SU-8 nanocomposites, are developed as photopatternable and electrically conductive nanocomposites for electrical lead micropatterning. The inclusion of xGnP, carbon-based conductive nanofiller, is intended to provide electrical conductivity, and the use of SU-8, photocurable host polymer, is designed to achieve both patternability and strong adhesion to polymer surfaces. First, the dependence of patterning characteristics (i.e., patterning thickness and patterning error) on xGnP content and UV exposure dose are extensively explored. The patterning thickness varies from 7.4 to 199.6 μm, and the patterning error changes from 12.1 to 32.7 μm with variations in xGnP content of 0.00–9.65 vol% and UV exposure dose of 500–5000 mJ/cm2. Next, an evolution in the electrical conductivity of xGnP/SU-8 nanocomposites with variation of xGnP content is explored to understand their electrical behavior. The electrical conductivity increases from 0.8 µS/m to 866.7 S/m with an increase in xGnP content of 0.00–9.65 vol%. Finally yet importantly, the applicability of xGnP/SU-8 nanocomposites to electrical lead micropatterning is demonstrated by photopatterning an electrical circuit for light-emitting diode chips using the xGnP/SU-8 nanocomposites on polydimethylsiloxane (PDMS) substrate. The findings of this study will contribute to a significant growth of polymer-based electrical leads and better understanding of photopatternable and electrically conductive nanocomposites. [ABSTRACT FROM AUTHOR]

Understanding changes in material properties through external stimuli is critical to validating the expected performance of materials as well as engineering material properties in a controlled manner. Here, we investigate a change in the c-axis electrical properties of graphite nanoflakes (GnFs) induced by gamma-ray irradiation, using conductive probe atomic force microscopy (CP-AFM). The fundamentals behind the change in their electrical properties are elucidated by analyzing the interlayer spacing, graphitization, and morphology. An increase in gamma-ray irradiation dose for GnFs leads to an exponential increase in the electrical conductance and a gradual decrease in the interlayer spacing, while accompanying indistinguishable changes in their morphology. Our experimental results suggest that the c-axis electrical conductance enhancement of GnFs with gamma-ray irradiation might be attributed to a reduction in interlayer spacing, though the created defects may also play a role. This study demonstrates that gamma-ray irradiation can be a promising route to tailor the electrical properties of GnFs. [ABSTRACT FROM AUTHOR]

Advancement in wearable healthcare technology allows a digital revolution in healthcare that is intended to extend life length and improve life quality. Until now, numerous efforts for wearable device-mediated healthcare systems have been focused on achieving accurate monitoring and robust operation by developing cutting-edge biosensors rather than by optimizing the placement position of well-established biosensors. Much therefore still remains unclear about the optimal position involved in biosensor placement. This leads to the need for systematic optimization of biosensor placement position. Here, the placement positions of 2 biosensor arrays (i.e., ECG-TC array and PPG-TC array) are optimized to achieve high-accuracy measurement and high-robustness operation in monitoring both body temperature and heart rate, which are commonly measured as core vital signs in wearable healthcare systems. The ECG-TC array is composed of an electrocardiography (ECG) sensor (for heart rate measurement) and a thermocouple (TC) sensor (for body temperature measurement) while the PPG-TC array consists of a photoplethysmography (PPG) sensor and a TC sensor. 34 major parts in the human body are scored in terms of monitoring accuracy (MA) and operational robustness (OR), which results in the MA index and OR index. Next, the body part having the maximum value, calculated as the product of two indices, is determined as the optimal placement position. The MA index is calculated from the signal magnitude of each biosensor and the OR index is assessed by quantifying the user accessibility, skin extensibility, and perspiration weight of each body part. Our study shows that the ECG-TC array needs to be placed on armpit, chest, and back thigh and the PPG-TC array on thumb, finger, and ear. This means the optimal placement position of biosensor-based wearable healthcare systems is affected by a combination of different biosensors. The findings of this study are expected to contribute to better understanding of biosensors and lead to further improvement in wearable healthcare devices. [ABSTRACT FROM AUTHOR]

Background:The impact of positive peritoneal cytology on the prognosis of cervical cancer is controversial. Thus, we performed a meta-analysis to determine its impact on recurrence, and to investigate correlations between abnormal cytology and/or lymph node metastasis in cervical cancer.Methods:A systematic literature review was conducted through July 2014. Odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated by standard meta-analysis techniques with the fixed-effects models, if there was no significant statistical heterogeneity across studies by using I2.Results:Of 303 studies retrieved, 6 were included in the meta-analysis. These six case-control observational studies included 1360 cervical cancer patients who showed negative peritoneal cytology and 64 who showed positive peritoneal cytology. Over the combined study period, 20 of 45 in the positive peritoneal cytology group experienced recurrence, whereas 88 of 539 controls did. The meta-analysis based on the fixed-effects model indicated a significant increase in the risk of recurrence in the positive peritoneal cytology group relative to the control group (OR: 4.47; 95% CI: 2.33-8.58, P<0.001, I2=0.0%). Moreover, the results of our meta-analysis suggested that the positive peritoneal cytology group displayed more lymph node metastasis than the negative peritoneal cytology group (OR: 3.73; 95% CI: 2.13-6.53, P<0.001, I2=0.0%).Conclusions:Although based mainly on retrospective observational studies, our meta-analysis indicates that abnormal peritoneal cytology may be strongly associated with poor prognosis in patients with cervical cancer. Future research should verify this relationship through prospective observational studies over a longer term. [ABSTRACT FROM AUTHOR]