In Situ Laser-Induced 3D Porous Graphene within Transparent Polymers for Encapsulation-Free and Tunable Ultrabroadband Terahertz Absorption.

Three-dimensional (3D) porous carbon materials have great potential for fabricating flexible tunable broadband absorbers owing to their high electrical conductivity, strong dielectric loss, and unique microstructure. Herein, we introduce an innovative method for synthesizing 3D porous graphene that incorporates advanced tuning and encapsulation processes to augment its functional efficacy. Through the modulation of both thermal and nonthermal interactions between a femtosecond (fs) laser and a polydimethylsiloxane (PDMS) film, we have synergistically fine-tuned the surface morphology and lattice properties of 3D porous graphene. This approach enabled us to create a flexible terahertz (THz) absorber with customizable characteristics, boasting an impressive absorbance range of 80%-99% in the 0.4-1.0 THz spectrum, alongside a peak reflection loss (RL) of up to 35.6 dB. Furthermore, we have successfully demonstrated the production of photoinduced 3D porous graphene within a PDMS film, which serves as both a carbon precursor and protective layer. This simplifies the conventional packaging process. These devices exhibit a RL of up to 41.6 dB and an absorption bandwidth of 2.5 THz (0.6-3.1 THz). Our study presents a production methodology for high-performance, flexible THz absorbers, offering a straightforward and innovative solution for the rapid development of sophisticated, flexible THz absorbing materials.

Prognostic factors for residual symptoms following percutaneous endoscopic lumbar discectomy.

To explore the risk factors for residual symptoms following percutaneous endoscopic lumbar discectomy (PELD). A retrospective case-controlled study. From January 2015 to December 2020, consecutive patients who underwent PELD for lumbar disc herniation (LDH) in our department were retrospectively studied. All the patients were followed-up at least two years. Residual symptoms were analyzed for association with baseline data, clinical feature, physical examination, and radiographic characteristics, which were used to detected the risk factors. A total of 339 patients were included in this study, with a mean follow-up of 28.7 ± 3.6 months. Of the enrolled patients, 90 (26.5%) patients experienced residual low back pain (LBP), and 76 (22.4%) patients experienced leg numbness (LN). Multivariate logistic regression analysis revealed that intervertebral disc calcification on CT scans (odd ratio, 0.480; 95% confidence interval: 0.247 ~ 0.932; P < 0.05) was independent risk factor for postoperative residual LBP with odd ratio and longer symptom duration was risk factor for postoperative residual LN (odd ratio, 2.231; 95% confidence interval:1.066 ~ 4.671; P < 0.05). Residual symptoms following transforaminal endoscopic surgery are quite prevalent. Intervertebral disc calcification is a protective factor for residual low back pain, and a longer symptom duration is a risk factor for residual leg numbness.

A Miniaturized Wireless Micropump Enabled by Confined Acoustic Streaming.

Miniaturization of health care, biomedical, and chemical systems is highly desirable for developing point-of-care testing (POCT) technologies. In system miniaturization, micropumps represent one of the major bottlenecks due to their undesirable pumping performance at such small sizes. Here, we developed a microelectromechanical system fabricated acoustic micropump based on an ultrahigh-frequency bulk acoustic wave resonator. The concept of an inner-boundary-confined acoustic jet was introduced to facilitate unidirectional flow. Benefitting from the high resonant frequency and confined acoustic streaming, the micropump reaches 32.620 kPa/cm3 (pressure/size) and 11.800 ml/min∙cm3 (flow rate/size), showing a 2-order-of-magnitude improvement in the energy transduction efficiency compared with the existing acoustic micropumps. As a proof of concept, the micropump was constructed as a wearable and wirelessly powered integrated drug delivery system with a size of only 9×9×9 mm3 and a weight of 1.16 g. It was demonstrated for ocular disease treatment through animal experimentation and a human pilot test. With superior pumping performance, miniaturized pump size, ultralow power consumption, and complementary metal-oxide-semiconductor compatibility, we expect it to be readily applied to various POCT applications including clinical diagnosis, prognosis, and drug delivery systems.

Numerical study of ice loads on different interfaces based on cohesive element formulation.

With the increase of marine activities in the Arctic area, the demand for reliable design of marine structures is growing. Numerous publications can be found regarding simulations of ice action on structures using cohesive element models of the ice. However, previous studies have rarely discussed the influence of structural form, that is, the form of ice-structure interaction interface, on the ice load. Thus, a more comprehensive understanding of the ice load on structures with different interface geometries needs to be explored. In the present paper, three-dimensional finite element models with the cohesive element method are developed to investigate the ice load on different structures. The numerical results are validated based on in-situ testing data and the results of the previous numerical model. Parametric studies considering structure widths, inclination angles, ice velocity as well as structure roughness are conducted to explore the horizontal force and failure process of the ice sheet. The process of ice-structure interaction and ice loads on different structural forms were discussed and simplified diagrams of ice load distribution on the interface were developed.

A Comparison of Negative Pressure and Conventional Therapy in Spine Infections: A Single-Center Retrospective Study.

Purpose: To investigate the effectiveness and safety of negative-pressure wound therapy (NPWT) in treating primary spinal infections. Methods: Patients who underwent surgical treatment for primary spinal infection between January 2018 and June 2021 were retrospectively evaluated. They were divided into two groups based on the type of surgery: one that underwent negative-pressure wound therapy (NPWT) and another that underwent conventional surgery (CVSG-Posterior debridement, bone grafting, fusion, and internal fixation in one stage). The two groups were compared in terms of the total operation time, total blood loss, total postoperative drainage, postoperative pain score, time for the postoperative erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to return to normal, postoperative complications, treatment time, and recurrence rate. Results: A total of 43 cases of spinal infection were evaluated, with 19 in the NPWT group and 24 in the CVSG group. The NPWT group had a superior postoperative drainage volume, antibiotic use time, erythrocyte sedimentation rate and CRP recovery times, VAS score at 3 months after the operation, and cure rate at 3 months after operation compared with the CVSG group. There were no significant variations in the total hospital stay and intraoperative blood loss between the two groups. Conclusions: This study supports the use of negative pressure in the treatment of a primary spinal infection and indicates that it has a notably better short-term clinical effect than conventional surgery. Additionally, its mid-term cure rate and recurrence rate are more desirable than those of conventional treatments.

Vacuum Sealing Drainage for Primary Thoracolumbar Spondylodiscitis: A Technical Note.

Primary spinal infection is a challenge for neurosurgeons. Here, for the first time, we introduced the vacuum sealing drainage (VSD) sponge into the intervertebral space for the primary thoracolumbar infection treatment. This study included 6 bedridden patients with thoracolumbar spondylodiscitis without deformity formation. All 6 patients were treated with the VSD in our hospital from June 30, 2018, to August 31, 2019. All 6 cases of thoracolumbar infection achieved clinical cure at 3-month follow-up, and no surgical-related mortalities occurred in our series. One patient died of acute cerebral infarction 5 months after surgery, and the remaining 5 patients completed a 12-month follow-up without recurrence. The JOA score of all 6 cases improved significantly after VSD treatment. VSD is feasible for safe and effective treatment for primary thoracolumbar infection. The short-term follow-up effect is definite.

Safety and efficacy of negative pressure wound therapy in treating deep surgical site infection after lumbar surgery.

PURPOSE: To evaluate the efficacy and safety of negative pressure wound therapy (NPWT) for post-operative deep surgical site infection (SSI) after posterior instrumented spinal surgery. METHODS: We retrospectively compared the clinical outcomes of NPWT with standard debridement for deep SSI after posterior instrumented spinal surgery from 2012 to 2020 in our department. The primary outcomes were peri-operative characteristics including positive organism results, duration of fever, and visual analogue scale (VAS) pain scores three days after re-operation. The secondary outcomes were post-operative characteristics including implant infection recurrence, implant retention rate, duration of hospitalization, and VAS at discharge. Pearson's chi-squared analysis (categorical) and Student's t test (continuous) were used to determine the differences. RESULTS: Thirty-four patients were included, of which 19 underwent NPWT, and 15 underwent standard debridement. Patients in the NPWT group all significantly improved primary outcomes including duration of fever after re-operation (0.95 ± 1.13 vs 4.07 ± 5.35, P = 0.001), positive organism results (14 of 19 vs 2 of 15, P < 0.01), and VAS at 3 days after re-operation (2.58 ± 0.69 vs 3.40 ± 1.06, P < 0.05). Patients in NPWT group exhibited significant decrease in implant infection recurrence (0 of 19 vs 5 of 15, P < 0.01), implant retention rate (19 of 19 vs 10 of 15, P < 0.01), duration of hospitalization (27.74 ± 10.95 vs 37.67 ± 13.67, P < 0.01). CONCLUSIONS: NPWT is a feasible and safe treatment option for deep SSI after posterior instrumented spinal surgery.

Fabrication of Multiple Parallel Microchannels in a Single Microgroove via the Heating Assisted MIMIC Technique.

For the first time, multiple parallel microchannels in a single microgroove have been fabricated by the heating-assisted micromolding in capillaries technique (HAMIMIC). Microchannel development, cross-sectional shape, and length were all explored in depth. The factors affecting the cross-sectional shape and length of the double-microchannel were also discussed. Finally, a special-shaped PDMS guiding mold was designed to control the cross-sectional shape and length of multiple parallel microchannels for controlled growth. The HAMIMIC technique provides a low-cost, straightforward, and repeatable way to create multiple parallel microchannels in a single microgroove, and will promote the progress of bifurcated vessels and thrombus vessels preparation technology.

Elastoplastic Model Framework for Saturated Soils Subjected to a Freeze-Thaw Cycle Based on Generalized Plasticity Theory.

The failures of soil slopes during the construction of high-speed railway caused by the soil after the freeze-thaw (F-T) cycle and the subsequent threat to construction safety are critical issues. An appropriate constitutive model for soils accurately describing the deformation characteristics of soil slopes after the F-T cycle is very important. Few constitutive models of soils incorporate the F-T cycle, and the associated flow rule has always been employed in previous models, which results in an overestimation of the deformation of soil exposed to the F-T cycle. Generalized plasticity theory is widely used to predict the performance of geotechnical materials and is especially well adapted to deal with this type of generalized cyclic loading (such as a freeze-thaw cycle), and it overcomes the shortcomings of the associated flow rule that causes larger shear deformation. To this end, an elastoplastic model framework based on generalized plasticity theory with double yield surfaces for saturated soils subjected to F-T cycles was developed. Two types of plastic deformation mechanisms, i.e., plastic volumetric compression and plastic shear, were considered in this elastoplastic model. It was found that this model can accurately predict the mechanical behavior and deformation characteristics of saturated soils after F-T cycles.