Prognostic Value of GRACE Risk Score Combined With Systemic Immune-Inflammation Index in Patients With ST-Segment Elevation Myocardial Infarction After Percutaneous Coronary Intervention.

The Global Registry of Acute Coronary Events (GRACE) score and the systemic immune-inflammation index (SII) were used independently to predict adverse outcomes in patients with ST-elevation myocardial infarction (STEMI). In this study, 1041 patients with STEMI were divided into 4 groups based on GRACE scores and optimal cutoff values for SII. SII was positively correlated with GRACE score (r = 0.164; P < .001). SII (HR, hazard ratio: 2.051; 95%CI: 1.249-3.368; P = .005) and GRACE score (HR: 7.625; 95%CI: 3.692-15.746; P < .001) were independent risk predictors of short-term major adverse cardiovascular events (MACEs). Taking the low SII+low GRACE group as the reference group, the short-term MACE HR of the high SII+high GRACE group was 40.470 (95%CI: 5.547-295.253). Comparing the area under the curve, the combined use of SII and GRACE scores can significantly improve the prediction efficiency of short-term MACE compared with the single use of SII and GRACE scores. In conclusion, SII may be positively correlated with GRACE score, and the combination of the two accurately predicted the occurrence of short-term MACE in STEMI patients after percutaneous coronary intervention (PCI).

Machine learning in the positron emission tomography imaging of Alzheimer's disease.

The utilization of machine learning techniques in medicine has exponentially increased over the last decades due to innovations in computer processing, algorithm development, and access to big data. Applications of machine learning techniques to neuroimaging specifically have unveiled various hidden interactions, structures, and mechanisms related to various neurological disorders. One application of interest is the imaging of Alzheimer's disease, the most common cause of progressive dementia. The diagnoses of Alzheimer's disease, mild cognitive impairment, and preclinical Alzheimer's disease have been difficult. Molecular imaging, particularly via PET scans, holds tremendous value in the imaging of Alzheimer's disease. To date, many novel algorithms have been developed with great success that leverage machine learning in the context of Alzheimer's disease. This review article provides an overview of the diverse applications of machine learning to PET imaging of Alzheimer's disease.

Cardiac contractility modulation ameliorates myocardial metabolic remodeling in a rabbit model of chronic heart failure through activation of AMPK and PPAR-α pathway.

Metabolic remodeling contributes to the pathological process of heart failure (HF). We explored the effects of cardiac contractility modulation (CCM) on myocardial metabolic remodeling in the rabbit model with HF. The HF in rabbit model was established by pressure uploading and then CCM was applied. We evaluated the cardiac structure and function by echocardiography, serum BNP level, and hematoxylin and eosin and Masson's trichrome staining. We detected the accumulation of glycogen and lipid droplets in myocardial tissues by periodic acid-Schiff and Oil Red O staining. Then, we measured the contents of glucose, free fatty acid (FFA), lactic acid, pyruvate, and adenosine triphosphate (ATP) levels in myocardial tissues by corresponding kits and the expression levels of key factors related to myocardial substrate uptake and utilization by western blotting were analyzed. CCM significantly restored the cardiac structure and function in the rabbit model with HF. CCM therapy further decreased the accumulation of glycogen and lipid droplets. Furthermore, CCM reduced the contents of FFA, glucose, and lactic acid, and increased pyruvate and ATP levels in HF tissues. The protein expression levels related to myocardial substrate uptake and utilization were markedly improved with CCM treatment by further activating adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor-α signaling pathways.

Dapagliflozin Attenuates Myocardial Fibrosis by Inhibiting the TGF-ß1/Smad Signaling Pathway in a Normoglycemic Rabbit Model of Chronic Heart Failure.

Recent studies have shown that sodium-glucose cotransporter-2 (SGLT2) inhibitors play a beneficial role for normoglycemic patients with heart failure (HF). However, the underlying mechanism remains largely unexplored. In the present study, we aimed to investigate the cardioprotective effect of SGLT2 inhibitors in a normoglycemic rabbit model of chronic heart failure (CHF) and its potential mechanism was also explored. A total of 24 male New Zealand white rabbits were randomly divided into the sham group, HF group, perindopril group, and dapagliflozin (DAPA) group. The normoglycemic CHF model was established by aortic constriction for 12 weeks. In the 13th week, DAPA (1 mg/kg/day) or perindopril (0.5 mg/kg/day) was administered by oral gavage daily for 10 weeks. Both the sham group and HF group were given normal saline via gavage. After 10 weeks, the heart structure and function were evaluated by echocardiography and plasma NT-proBNP. Moreover, cardiac fibrosis was analyzed using immunohistochemistry, Masson's trichrome staining, and Western blotting analysis. The results showed that DAPA improved the myocardial structure and function of normoglycemic CHF rabbits and ameliorated myocardial fibrosis. Further study indicated that DAPA suppressed cardiac fibrosis by inhibiting the transforming growth factor ß1 (TGF-ß1)/Smad signaling pathway. Collectively, our findings showed that DAPA could ameliorate cardiac fibrosis in normoglycemic CHF rabbits by inhibiting the TGF-ß1/Smad signaling pathway.

Nomogram for Predicting In-Hospital Mortality in Patients with Acute ST-Elevation Myocardial Infarction Complicated by Cardiogenic Shock after Primary Percutaneous Coronary Intervention.

Background: Mortality after percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI) patients with cardiogenic shock (CS) remains high. However, the real-world risk factors for mortality in these patients are poorly defined. Objective: The aim of this study is to establish a clinical prognostic nomogram for predicting in-hospital mortality after primary PCI in STEMI patients with CS. Methods: This retrospective, multicenter, observational study included STEMI patients with CS who underwent PCI at 39 hospitals in Hebei Province from January 2018 to December 2019. A multivariate logistic regression model was used to identify the factors associated with in-hospital mortality. These factors were then incorporated into a nomogram and its performance was evaluated by discrimination, calibration, and clinical utility. Results: This study included 274 patients, among whom 179 died in hospital. Sex, random blood glucose on admission, ejection fraction after PCI, no-reflow, and intra-aortic balloon pump (IABP) were independently associated with in-hospital mortality (all P < 0.05). In the training set, the nomogram showed a C-index of 0.819, goodness-of-fit of 0.08, and area under the receiver operating characteristic curve (AUC) of 0.819 (95%CI = 0.759-0.879). In the testing set, the C-index was 0.842, goodness-of-fit was 0.585, and AUC was 0.842 (95%CI = 0.715-0.970). The results indicate that the nomogram had good discrimination and good prediction accuracy and could achieve a good net benefit. Conclusion: We established and validated a nomogram that provided individual prediction of in-hospital mortality for STEMI patients with CS after PCI in a Chinese population.

A physics/circuit-based switching model for carbon-based resistive memory with sp2/sp3 cluster conversion.

The switching mechanism in carbon-based resistive-switching random access memory is modelled using a percolation approach built on the low-temperature transition between phases sp(3) (diamond-like and high-resistive state) and sp(2) (graphite-like and low-resistive state) for a matrix of carbon clusters in a diamond-like carbon film. The switching process is described using a random circuit breaker network with each breaker controlled by the resistance of clusters sp(2)/sp(3). The key feature of the proposed model is the thermal stress-induced transition from sp(2) to sp(3) phase and the electric field-induced transition from sp(3) to sp(2) phase. Compared with experiments on the switching biasing scheme, a good agreement between simulation and measured data validated the accuracy of the proposed model.

A novel solid-state thermal rectifier based on reduced graphene oxide.

Recently, manipulating heat transport by phononic devices has received significant attention, in which phonon--a heat pulse through lattice, is used to carry energy. In addition to heat control, the thermal devices might also have broad applications in the renewable energy engineering, such as thermoelectric energy harvesting. Elementary phononic devices such as diode, transistor and logic devices have been theoretically proposed. In this work, we experimentally create a macroscopic scale thermal rectifier based on reduced graphene oxide. Obvious thermal rectification ratio up to 1.21 under 12 K temperature bias has been observed. Moreover, this ratio can be enhanced further by increasing the asymmetric ratio. Collectively, our results raise the exciting prospect that the realization of macroscopic phononic device with large-area graphene based materials is technologically feasible, which may open up important applications in thermal circuits and thermal management.

Static behavior of a graphene-based sound-emitting device.

Due to the extremely high thermal conductivity and low heat capacity per unit area of graphene, it is possible to fabricate an efficient sound-emitting device based on the thermoacoustic effect with no mechanical vibration. In this paper, the fundamental performance of this new graphene sound-emitting device (G-SED) is investigated in terms of its static behavior. The sound amplitude mapping shows that the G-SED has good sound performance under 0.01 W. The sound frequency spectra measured at different distances and angles show that the G-SED has good sound directivity. It is possible to realize sound wave manipulation by using an array of G-SEDs. The relationship between the temperature of graphene and the sound frequency was investigated by a thermal imaging instrument. The fast transient sound response in real time was recorded by applying 60 µs short time multi-pulses and single-pulse. The stable sound emission at a constant sound pressure amplitude with low noise was observed for continuous operation under a fixed frequency over several hours. Such significant performances in this G-SED indicate broad applications, and shed light on the use of graphene in the field of acoustics.

Single-layer graphene sound-emitting devices: experiments and modeling.

Single-layer graphene (SLG) was demonstrated to emit sound. The sound emission from SLG had a significant flat frequency response in the wide ultrasound range from 20 kHz to 50 kHz. SLG can produce a sound pressure level (SPL) as high as 95 dB at a distance of 5 cm with a sound frequency of 20 kHz. The SPL value is among the highest reported to date for sound-emitting devices (SEDs) based on the thermoacoustic effect. A theoretical model was established to analyze the sound emission from SLG. The theoretical results are in good agreement with the experimental results. Conventional acoustic devices with a large size can be reduced to the nano-scale by using this novel SLG-SED material. It has the potential to be widely used in speakers, buzzers, earphones, ultrasonic transducer, etc.

Graphene-on-paper sound source devices.

We demonstrate an interesting phenomenon that graphene can emit sound. The application of graphene can be expanded in the acoustic field. Graphene-on-paper sound source devices are made by patterning graphene on paper substrates. Three graphene sheet samples with the thickness of 100, 60, and 20 nm were fabricated. Sound emission from graphene is measured as a function of power, distance, angle, and frequency in the far-field. The theoretical model of air/graphene/paper/PCB board multilayer structure is established to analyze the sound directivity, frequency response, and efficiency. Measured sound pressure level (SPL) and efficiency are in good agreement with theoretical results. It is found that graphene has a significant flat frequency response in the wide ultrasound range 20-50 kHz. In addition, the thinner graphene sheets can produce higher SPL due to its lower heat capacity per unit area (HCPUA). The infrared thermal images reveal that a thermoacoustic effect is the working principle. We find that the sound performance mainly depends on the HCPUA of the conductor and the thermal properties of the substrate. The paper-based graphene sound source devices have highly reliable, flexible, no mechanical vibration, simple structure and high performance characteristics. It could open wide applications in multimedia, consumer electronics, biological, medical, and many other areas.

Modeling and design optimization of large-deflection piezoelectric folded cantilever microactuators.

This paper presents a novel, large-deflection piezoelectric folded cantilever microactuator (PFCM). A multimorph model for the large-deflection PFCM is derived, in which unified formulas for deflection angle and vertical displacement of N-level PFCM are obtained. Based on the model, multilayer PFCMs using PZT film are designed and optimized. The large-deflection PFCM is extensively applicable to micro-devices or microsystem applications such as micro-optical switches, microelectromechanical systems (MEMS) scanners, and so forth.

Fabrication of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) microstructures using soft lithography for scaffold applications.

This paper reports two soft lithographic methods, micromolding and hot embossing, to produce biodegradable poly (3-hydroxybutyrate-co-3-ftydroxyhexanoate) (PHBHHx) arrays of microstructures for hosting and culturing cells in a local microenvironment by controlled shape. Silicon masters with high-aspect-ratio microfeatures were fabricated using KOH and DRIE anisotropic etching. These silicon masters were used as molds to construct PHBHHx microstructures using micromolding and hot embossing. Using silicon rather than conventional PDMS as molds allowed microstructures with feature size of 20 microm and height of 100 microm to be realized. PHBHHx microstructures with different configurations including circles, rectangles, and octagons were fabricated to investigate the effects of topography on cell culture. Mouse fibroblast cell lines L929 were cultured on PHBHHx microstructures in vitro to investigate the biocompatibility. This study demonstrates the feasibility of microfabrication of PHBHHx structures with micro-scale feature size using soft lithography, and the results show that PHBHHx microstructures can be created to mimic cellular microenvironment for cell culture, providing a convenient means to investigate relationships of microstructures and cell functions.

Design and analysis of a PZT-based micromachined acoustic sensor with increased sensitivity.

The ever-growing applications of lead zirconate titanate (PZT) thin films to sensing devices have given birth to a variety of microsensors. This paper presents the design and theoretical analysis of a PZT-based micro acoustic sensor that uses interdigital electrodes (IDE) and in-plane polarization (IPP) instead of commonly used parallel plate-electrodes (PPE) and through-thickness polarization (TTP). The sensitivity of IDE-based sensors is increased due to the small capacitance of the interdigital capacitor and the large and adjustable electrode spacing. In addition, the sensitivity takes advantage of a large piezoelectric coefficient d33 rather than d31, which is used in PPE-based sensors, resulting in a further improvement in the sensitivity. Laminated beam theory is used to analyze the laminated piezoelectric sensors, and the capacitance of the IDE is deduced by using conformal mapping and partial capacitance techniques. Analytical formulations for predicting the sensitivity of both PPE- and IDE-based microsensors are presented, and factors that influence sensitivity are discussed in detail. Results show that the IDE and IPP can improve the sensitivity significantly.