Centimeter-scale nanomechanical resonators with low dissipation.

High-aspect-ratio mechanical resonators are pivotal in precision sensing, from macroscopic gravitational wave detectors to nanoscale acoustics. However, fabrication challenges and high computational costs have limited the length-to-thickness ratio of these devices, leaving a largely unexplored regime in nano-engineering. We present nanomechanical resonators that extend centimeters in length yet retain nanometer thickness. We explore this expanded design space using an optimization approach which judiciously employs fast millimeter-scale simulations to steer the more computationally intensive centimeter-scale design optimization. By employing delicate nanofabrication techniques, our approach ensures high-yield realization, experimentally confirming room-temperature quality factors close to theoretical predictions. The synergy between nanofabrication, design optimization guided by machine learning, and precision engineering opens a solid-state path to room-temperature quality factors approaching 10 billion at kilohertz mechanical frequencies - comparable to the performance of leading cryogenic resonators and levitated nanospheres, even under significantly less stringent temperature and vacuum conditions.

High-Strength Amorphous Silicon Carbide for Nanomechanics.

For decades, mechanical resonators with high sensitivity have been realized using thin-film materials under high tensile loads. Although there are remarkable strides in achieving low-dissipation mechanical sensors by utilizing high tensile stress, the performance of even the best strategy is limited by the tensile fracture strength of the resonator materials. In this study, a wafer-scale amorphous thin film is uncovered, which has the highest ultimate tensile strength ever measured for a nanostructured amorphous material. This silicon carbide (SiC) material exhibits an ultimate tensile strength of over 10 GPa, reaching the regime reserved for strong crystalline materials and approaching levels experimentally shown in graphene nanoribbons. Amorphous SiC strings with high aspect ratios are fabricated, with mechanical modes exceeding quality factors 108 at room temperature, the highest value achieves among SiC resonators. These performances are demonstrated faithfully after characterizing the mechanical properties of the thin film using the resonance behaviors of free-standing resonators. This robust thin-film material has significant potential for applications in nanomechanical sensors, solar cells, biological applications, space exploration, and other areas requiring strength and stability in dynamic environments. The findings of this study open up new possibilities for the use of amorphous thin-film materials in high-performance applications.

Spiderweb Nanomechanical Resonators via Bayesian Optimization: Inspired by Nature and Guided by Machine Learning.

From ultrasensitive detectors of fundamental forces to quantum networks and sensors, mechanical resonators are enabling next-generation technologies to operate in room-temperature environments. Currently, silicon nitride nanoresonators stand as a leading microchip platform in these advances by allowing for mechanical resonators whose motion is remarkably isolated from ambient thermal noise. However, to date, human intuition has remained the driving force behind design processes. Here, inspired by nature and guided by machine learning, a spiderweb nanomechanical resonator is developed that exhibits vibration modes, which are isolated from ambient thermal environments via a novel "torsional soft-clamping" mechanism discovered by the data-driven optimization algorithm. This bioinspired resonator is then fabricated, experimentally confirming a new paradigm in mechanics with quality factors above 1 billion in room-temperature environments. In contrast to other state-of-the-art resonators, this milestone is achieved with a compact design that does not require sub-micrometer lithographic features or complex phononic bandgaps, making it significantly easier and cheaper to manufacture at large scales. These results demonstrate the ability of machine learning to work in tandem with human intuition to augment creative possibilities and uncover new strategies in computing and nanotechnology.

Indoor Air Quality Analysis Using Deep Learning with Sensor Data.

Indoor air quality analysis is of interest to understand the abnormal atmospheric phenomena and external factors that affect air quality. By recording and analyzing quality measurements, we are able to observe patterns in the measurements and predict the air quality of near future. We designed a microchip made out of sensors that is capable of periodically recording measurements, and proposed a model that estimates atmospheric changes using deep learning. In addition, we developed an efficient algorithm to determine the optimal observation period for accurate air quality prediction. Experimental results with real-world data demonstrate the feasibility of our approach.

Oral vaccination of mice with Tremella fuciformis yeast-like conidium cells expressing HBsAg.

Tremella fuciformis yeast-like conidium (YLC) cells were transformed by co-cultivation with Agrobacterium cells harboring the hepatitis B surface antigen (HBsAg) gene construct under the control of the CaMV35S promoter. Integration of HBsAg DNA into the YLC genome was confirmed by PCR and dot-blot hybridization. Immunoblotting verified expression of the recombinant protein. Oral administration of YLC cells expressing HBsAg in mice significantly increased anti-HBsAg antibody titer levels using a double prime-boost strategy that combined parenteral and oral HBsAg boosters.

Negative association between plasma aldosterone concentration/plasma renin activity and morning blood pressure surge in never-treated hypertensive patients.

Morning blood pressure (BP) surge (MS) has been known to be a predictor of cardiovascular events. Currently, few studies have evaluated the underlying mechanism underlying MS, which may include neurohormonal factors and the renin-angiotensin-aldosterone system (RAAS). This study aimed to examine plasma aldosterone concentration (PAC) and plasma renin activity (PRA) and BP parameters with or without MS in never-treated subjects with essential hypertension. This cross-sectional study included a total of 261 patients (mean age: 48.8 years; 60.5% male) with never-treated essential hypertension who were registered in a working group at The Catholic University of Korea. The patients were divided into the MS group, which was defined as having the highest quartile of morning BP increase from sleep (>31 mmHg; n = 66) and the non-MS group (≤31 mmHg; n = 195). We collected 24-h ambulatory BP, pulse wave velocity, ankle brachial index, PAC and PRA from all patients. The measured PAC and PRA were lower in the MS group than in the non-MS group (PAC: 9.0 ± 5.4 ng/dl versus 12.2 ± 8.7 ng/dl, p < 0.001; PRA: 1.7 ± 1.3 ng/ml/h versus 2.6 ± 3.6 ng/ml/h, p = 0.002). The MS group had greater variations in daytime, nighttime and 24-h systolic blood pressure (SBPs) than the non-MS group (24-h SBP: 15.6 ± 4.4 mm Hg for the non-MS group and 18.9 ± 4.9 mmHg for the MS group; p < 0.001 for each). It is generally accepted that the sympathetic nervous system plays a major role in the regulation of BP variability. Therefore, further studies on sympathetic nervous system activation in hypertensives with extreme MS are needed. MS in enrolled patients who were at relatively low risk in this study may be less affected by the RAAS.

Mechanical wounding of yeast-like conidium cells of Tremella fuciformis makes them susceptible to Agrobacterium-mediated transformation.

We developed an efficient protocol that makes possible the practical use of Agrobacterium to transform the yeast-like conidia of Tremella fuciformis. Mechanical wounding of fungal cells prior to co-cultivation with Agrobacterium cells greatly improved transformation efficiency.

Improvement of arterial stiffness in the transition from acute decompensated heart failure to chronic compensated heart failure.

BACKGROUND: Pulse wave velocity (PWV) is a well-established marker for aortic stiffness and may be a prognostic factor in heart failure (HF). This study investigates whether PWV changes as patients transition from acute decompensated heart failure (ADHF) to chronic compensated heart failure (CCHF). HYPOTHESIS: Arterial stiffness is related with the development of HF. METHODS: Regional PWV was prospectively measured using noninvasive applanation tonometry in consecutive ADHF patients (n = 55). PWV measurements of 45 patients were taken at admission and 3-month follow-up (F/U). RESULTS: Central and upper-extremity PWV, but not lower-extremity PWVs, were found to have improved after 3 months compared with the admission PWV (central: 8.73 ± 1.17 vs 8.39 ± 0.99 m/s, P = 0.018; upper extremity: 8.59 ± 0.84 vs 8.33 ± 0.82 m/s, P = 0.028). Multivariate logistic regression analyses revealed that low-density lipoprotein cholesterol was significantly associated with the change of PWV in HF (odds ratio: 1.037, 95% confidence interval: 1.003-1.071, P = 0.030). In preserved left ventricular ejection fraction patients (n = 26) and ischemic patients (n = 31), central and upper-extremity PWVs improved over the admission PWV at 3-month F/U. CONCLUSIONS: The present results indicate that central and upper-extremity PWVs, but not lower-extremity PWV, are increased in ADHF and improve as patients transition from ADHF to CCHF.

The effect of cilostazol on stent thrombosis after drug-eluting stent implantation.

BACKGROUND AND OBJECTIVES: Placement of drug-eluting stents (DES) can be complicated by stent thrombosis; prophylactic antiplatelet therapy has been used to prevent such events. We evaluated the efficacy of cilostazol with regard to stent thrombosis as adjunctive antiplatelet therapy. SUBJECTS AND METHODS: A total of 1,315 patients (846 males, 469 females) were prospectively enrolled and analyzed for the frequency of stent thrombosis. Patients with known risk factors for stent thrombosis, except diabetes and acute coronary syndrome, were excluded from the study. All patients maintained antiplatelet therapy for at least six months. To evaluate the effects of cilostazol as another option for antiplatelet therapy, triple antiplatelet therapy (aspirin+clopidogrel+cilostazol, n=502) was compared to dual antiplatelet therapy (aspirin+clopidogrel, n=813). Six months after stent placement, all patients received only two antiplatelet drugs: treatment either with cilostazol+aspirin (cilostazol group) or clopidogrel+aspirin (clopidogrel group). There were 1,033 patients (396 in cilostazol group and 637 in clopidogrel group) that maintained antiplatelet therapy for at least 12 months and were included in this study. Stent thrombosis was defined and classified according to the definition reported by the Academic Research Consortium (ARC). RESULTS: defined and classified according to the definition reported by the Academic Research Consortium (ARC). RESULTS: During follow-up (561.7+/-251.4 days), 15 patients (1.14%) developed stent thrombosis between day 1 to day 657. Stent thrombosis occurred in seven patients (1.39%) on triple antiplatelet therapy and four patients (0.49%) on dual antiplatelet therapy (p=NS) within the first six months after stenting. Six months and later, after stent implantation, one patient (0.25%) developed stent thrombosis in the cilostazol group, and three (0.47%) in the clopidogrel group (p=NS). CONCLUSION: During the first six months after DES triple antiplatelet therapy may be more effective than dual antiplatelet therapy for the prevention of stent thrombosis. However, after the first six months, dual antiplatelet treatment, with aspirin and cilostazol, may have a better cost benefit ratio for the prevention of stent thrombosis.

Death caused by simultaneous subacute stent thrombosis of sirolimus-eluting stents in left anterior descending artery and left circumflex artery.

Simultaneous drug-eluting stent thrombosis in multivessel disease is a low incidence, but could cause lethal clinical event. We report a case with death caused by simultaneous subacute stent thrombosis of sirolimus-eluting stents in the proximal left anterior descending artery and in the proximal left circumflex artery.

Significance of inflammatory markers in diabetic patients with stable coronary artery disease.

BACKGROUND/AIMS: Patients with diabetes are prone to coronary artery disease (CAD); however, the majority of diabetic patients show normal coronary arteries. We examined differences in the clinical aspects of diabetic patients with insignificant and with significant stenosis of the coronary artery. METHODS: A total of 418 consecutive diabetic patients with stable angina who had undergone coronary angiography from January 2004 to March 2007 were included in this study. Patients were subdivided into control and CAD groups and then clinical characteristics and CAD-associated factors were evaluated. RESULTS: A total of 92 (22%) patients were assigned to the control group and 326 (78%) patients were assigned to the CAD group. Using univariate regression analysis, we found that patients with CAD were significantly older (control vs. CAD; 59+/-21 vs. 64.7+/-33.7, years, p<0.001), had a longer duration of diabetes (8.2+/-21.8 vs. 10.2+/-29.8, years, p=0.027), higher titers of high sensitivity C-reactive protein (hsCRP; 0.3+/-6.79 vs. 0.9+/-12.6, mg/dL, p=0.015), and increased hemoglobin A1c (HbA1c) levels (7.1+/-3.8 vs. 7.5+/-4.8, %, p=0.007) compared to control patients. Multivariate regression analysis showed that only differences in age, hsCRP, and HbA1c were statistically significant. When patients were subdivided into groups based on hsCRP levels (208 patients in the low group [49.8%], 210 patients in the high group [50.2%]), we found that patients with higher hsCRP levels showed more frequent multivessel disease. CONCLUSIONS: In diabetic patients, age, hsCRP, and HbA1c were associated with stable CAD. Among these factors, hsCRP levels were significantly correlated with multivessel involvement in diabetic CAD. Therefore, high hsCRP levels may be a strong predictor for atherosclerotic progression of the coronary arteries in diabetic patients, suggesting that regular screening tests should be performed.

Serum carboxy-terminal propeptide of type I procollagen (PIP) is a marker of diastolic dysfunction in patients with early type 2 diabetes mellitus.

This study was designed to investigate whether the serum concentration of the carboxy-terminal propeptide of procollagen type I (PIP), a marker of myocardial fibrosis, is related to changes of the ventricular filling dynamics in patients with early type 2 diabetes mellitus (T2DM). The T2DM group had lower mitral and tricuspid E/A ratios than the control group. Serum PIP was higher in patients with T2DM than in controls (131.1+/-45.6 vs. 109.3+/-32.5 ng/mL, p=0.039). A-Ar, an estimate of passive diastolic function, was inversely related to serum PIP levels in T2DM (r=-0.42, p=0.03). These results show a relation between LV diastolic function and serum PIP levels in early T2DM.

Clinical and angiographic characteristics of acute myocardial infarction caused by vasospastic angina without organic coronary heart disease.

BACKGROUND: Vasospastic angina (VA) can occasionally cause acute myocardial infarction (AMI). METHODS AND RESULTS: From January 2003 to June 2005, coronary spastic angina was diagnosed in 292 patients by performing spasm provocation tests. Among the 292 patients, 21 (7.2% of all the VA patients) had an AMI. There were 20 patients who initially visited the emergency room for AMI without suffering prior VA. One patient with a history of VA had an AMI when he discontinued his medication. Among the 21 VA patients with AMI, 14 had experienced severe emotional stress before they visited the emergency room. The spasm provocation test showed that the VA patients with AMI had more multivessel and diffuse spasm than the VA patients without AMI (p<0.001). CONCLUSION: Clinically, the VA patients with AMI usually had their first symptom of VA as the severe chest pain of AMI. Two-thirds of the VA patients with AMI had experienced emotional stress before their AMI. Angiographically, the spasm provocation test for VA patients with AMI showed more multivessel and diffuse spasm than in VA patients without AMI.

Transient beta-glucuronidase expression in lily (Lilium longflorum L.) pollen via wounding-assisted Agrobacterium-mediated transformation.

A pollen-based transient expression system has been developed. Lily pollen grains, wounded by vigorous shaking in the presence of aluminum oxide particles, were transformed by infiltration with Agrobacterium tumefaciens LBA4404 cells harboring the beta-glucuronidase (GUS) gene construct, pBI121. In histochemical and fluorometric GUS analysis, the wounding processes allowed efficient transformation and, in cDNA blot hybridization, GUS mRNA synthesis was clearly detected. Lily pollen with appropriate wounds, therefore, can be used conveniently for the rapid production of recombinant proteins.