High-Speed Photothermal Patterning of Doped Polymer Films.

Organic semiconductors (OSCs) offer a new avenue to the next-generation electronics, but the lack of a scalable and inexpensive nanoscale patterning/deposition technique still limits their use in electronic applications. Recently, a new lithographic etching technique has been introduced that uses molecular dopants to reduce semiconducting polymer solubility in solvents and a direct-write laser to remove dopants locally, enabling rapid OSC etching with diffraction limited resolution. Previous publications postulated that the reaction that enables patterning is a photochemical reaction between photoexcited dopants with neutral solvent molecules. In this work, we analyze the photoinduced dissolution kinetics of F4TCNQ doped P3HT films using time-resolved in situ optical probing. We find two competing mechanisms that control de-doping and dissolution: the first is the photochemical reaction posited in the literature, and the second involves direct heating of the polymer by the laser, inducing increased solubility for both the polymer and dopant. We show that the wavelength-specific photochemical effect is dominant in low photon doses while the photothermal effect is dominant with high excitation rates regardless of laser wavelength. With sufficiently high optical intensity input, the photothermal mechanism can in principle achieve a high writing speed up to 1 m/s. Our findings bring new insights into the mechanisms behind laser direct writing of OSCs based on dopant induced solubility control and enable ultraprecise fabrications of various device configurations in large-scale manufacturing

Experimental demonstration of a free space cylindrical cloak without superluminal propagation

We experimentally demonstrated an alternative approach of invisibility cloaking that can combine technical advantages of all current major cloaking strategies in a unified manner and thus can solve bottlenecks of individual strategies. A broadband cylindrical invisibility cloak in free space is designed based on scattering cancellation (the approach of previous plasmonic cloaking), and implemented with anisotropic metamaterials (a fundamental property of singular-transformation cloaks). Particularly, non-superluminal propagation of electromagnetic waves, a superior advantage of non-Euclidian-transformation cloaks constructed with complex branch cuts, is inherited in this design, and thus is the reason of its relatively broad bandwidth. This demonstration provides the possibility for future practical implementation of cloaking devices at large scales in free space.Comment: 16 pages, 3 figures, accepted by Physical Review Letter

Intrathecal Injection of Spironolactone Attenuates Radicular Pain by Inhibition of Spinal Microglia Activation in a Rat Model

Microglia might play an important role in nociceptive processing and hyperalgesia by neuroinflammatory process. Mineralocorticoid receptor (MR) expressed on microglia might play a central role in the modulation of microglia activity. However the roles of microglia and MR in radicular pain were not well understood. This study sought to investigate whether selective MR antagonist spironolactone develop antinociceptive effects on radicular pain by inhibition neuroinflammation induced by spinal microglia activation.Radicular pain was produced by chronic compression of the dorsal root ganglia with SURGIFLO™. The expression of microglia, interleukin beta (IL-1β), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), NR1 subunit of the NMDA receptor (t-NR1), and NR1 subunit phosphorylated at Ser896 (p-NR1) were also markedly up-regulated. Intrathecal injection of spironolactone significantly attenuated pain behaviors as well as the expression of microglia, IL-1β, TNF-α, t-NR1, and p-NR1, whereas the production of IL-6 wasn't affected.These results suggest that intrathecal delivery spironolactone has therapeutic effects on radicular pain in rats. Decreasing the activation of glial cells, the production of proinflammatory cytokines and down-regulating the expression and phosphorylation of NMDA receptors in the spinal dorsal horn and dorsal root ganglia are the main mechanisms contributing to its beneficial effects

Study of Nano-scale Non-equilibrium Thermal Transport Using Far-field and Near-field Ultrafast Optical Microscopy

As modern technology advances keep pushing the size limit of electronic devices down to nanoscale, the densities of elementary units on integrated circuits (ICs) are drastically increased. One of the major deleterious effects is the huge density of heat generated that may lead to device malfunction or break-down. Therefore, nanoscale thermal management has become an important research topic, which requires progress in both fundamental understanding of nanoscale thermal physics on the material level and novel engineering strategies on the device end. On the other hand, recent advances in material synthesis, processing, and nanofabrication have made available rich families of new materials with unprecedented properties that elevate them to potential candidates for next-generation electronic devices. Characterizing such materials with structure that varies on the length scale of a few nanometers, such as nanowires, 2D materials and Van de Waals heterostructures, necessitates new methodologies and experimental strategies that can unveil unexplored thermal physics mechanisms. In this thesis, we describe our recent work on developing a novel and comprehensive optical diagnostic platform with ultra-high sensitivity to conduct thermal measurements for a wild range of nanomaterials and nanostructures. Specifically, femto-second laser based optical pump-probe scheme is utilized to enable ultra-high temporal resolution (~300 fs), which offers access to investigating ultrafast dynamic processes that fundamental thermal carriers undergo in extreme non-equilibrium circumstances. Based on the ultra-fast optical pump-probe microscopy technique, we have extended the time-domain thermo-reflectance (TDTR) technique to frequency domain and constructed the time-resolved frequency domain thermo-reflectance (Tr-FDTR) measurement to characterize the transient material thermal properties across different time scales, from 100 fs to 10 ns upon ultrafast thermal excitation. Unlike TDTR, this newly developed methodology takes full advantage of the ultra-high time resolution embedded in ultra-fast pump-probe technique, for measuring dynamic thermal transport processes. Next, we have integrated the developed ultra-fast optical pump-probe microscopy technique with an atomic force microscopy (AFM) instrument in the configuration of scattering near-field scanning optical microscopy (s-NSOM). The combination of ultra-high temporal resolution and ultra-high spatial resolution (~10 nm) makes this comprehensive optical diagnostics platform an unprecedented tool for studying nanoscale transient heat transfer and energy transport processes. With this powerful tool, we have successfully demonstrated the ability to capture the two-dimensional ‘snapshots’ of the ultra-fast photoexcitation process in silicon nanowires, and the ability to extract the near-field signals for studying material dynamics at a level that is not achievable with any of the current far-field techniques.The developed instrumentation has the potential to contribute a new technology for investigating ultra-fast nanoscale thermal transport phenomena in both equilibrium and non-equilibrium regimes, which are currently completely unattainable with conventional thermal measurement techniques. The first major contribution will be the ability to directly investigate the ultrafast non-equilibrium thermal transport processes that various material systems undergo in response to an abrupt release of thermal energy. Key to the success of this effort is to utilize the femto-second time resolution to characterize the different behaviors of thermal energy carriers (electrons and phonons) and their interactions across all the stages (from sub-picosecond to nanosecond time range). This technique will enable us to experimentally verify new thermal transport mechanisms that emerge in unconventional material systems. The second major contribution is that the developed ultrafast thermal measurement technique can be extended down to nanoscale, thus offering the opportunity to interrogate fundamental nanoscale heat transfer problems. Therefore, we anticipate with confidence that this work will not only push the boundaries of our understandings of the nanoscale heat transfer and energy transport, but also shed light on unconventional mechanisms of thermal transport in newly discovered material systems that may be potential candidates for the next-generation electronics, and suggest new strategies for engineering nanomaterials for nanoscale thermal management in the next-generation electronics

Impact of sarcopenia in elderly patients undergoing elective total hip arthroplasty on postoperative outcomes: a propensity score-matched study

Abstract Objective Frailty poses a crucial risk for postoperative complications in the elderly, with sarcopenia being a key component. The impact of sarcopenia on postoperative outcomes after total hip arthroplasty (THA) is still unclear. This study investigated the potential link between sarcopenia and postoperative outcomes among elderly THA patients. Methods Totally 198 older patients were enrolled in this study. Sarcopenia in this group was determined by assessing the skeletal muscle index, which was measured using computed tomography at the 12th thoracic vertebra and analyzed semi-automatically with MATLAB R2020a. Propensity score matching (PSM) was employed to evaluate postoperative complications of grade II and above (POCIIs). Results The variables balanced using PSM contained age, sex and comorbidities including hypertension, diabetes, hyperlipidemia and COPD. Before PSM, sarcopenic patients with reduced BMI (24.02 ± 0.24 vs. 27.11 ± 0.66, P < 0.001) showed higher POCIIs rates (48.31% vs. 15%, P = 0.009) and more walking-assisted discharge instances (85.96% vs. 60%, P = 0.017) compared with non-sarcopenia patients. After PSM, this group maintained reduced BMI (23.47 ± 0.85 vs. 27.11 ± 0.66, P = 0.002), with increased POCIIs rates (54.41% vs. 15%, P = 0.002) and heightened reliance on walking assistance at discharge (86.96% vs. 60%, P = 0.008). Conclusion Sarcopenia patients exhibited a higher incidence of POCIIs and poorer physical function at discharge. Sarcopenia could serve as a valuable prognostic indicator for elderly patients undergoing elective THA

Early dynamics of cavitation bubbles generated during ns laser ablation of submerged targets.

In this study, we observe and study the early evolution of cavitation bubbles generated during pulsed laser ablation of titanium targets in different liquid environments utilizing a high-resolution stroboscopic shadowgraphy system. A hydrodynamic model is proposed to calculate the early pressure changes within the bubble and in the surrounding fluid. Our results show that the cavitation bubble is a low-pressure region that is bounded by a high-pressure fluid lamina after the incipient stage, and its evolution is primarily affected by the liquid density. Moreover, the initial bubble pressure increases substantially in high viscosity liquids. This work illuminates how the liquid properties affect the early bubble dynamics and is a step towards a deeper understanding of laser-materials interactions in liquid environments

Study on the Role of Salicylic Acid in Watermelon-Resistant Fusarium Wilt under Different Growth Conditions

Background: Fusarium wilt disease is leading threat to watermelon yield and quality. Different cultivation cropping systems have been reported as safe and efficient methods to control watermelon Fusarium wilt. However, the role of salicylic acid (SA) in watermelon resistance to Fusarium wilt in these different cultivation systems remains unknown. Methods: in this experiment, we used RNA-seq and qRT-PCR to study the effect of SA biosynthesis on improving watermelon health, demonstrating how it may be responsible for Fusarium wilt resistance under continuous monocropping and oilseed rape rotation systems. Results: the results revealed that the expression of the CIPALs genes was key to SA accumulation in watermelon roots. We observed that the NPR family genes may play different roles in responding to the SA signal. Differentially expressed NPRs and WRKYs may interact with other phytohormones, leading to the amelioration of watermelon Fusarium wilt. Conclusions: further understanding of gene expression patterns will pave the way for interventions that effectively control the disease