3D Printing of Bi2Te3-Based Thermoelectric Materials with High Performance and Shape Controllability.

Thermoelectric (TE) energy conversion technology provides a promising way to improve the efficiency of fossil energy by generating electricity from low-grade waste heat. With regard to these applications, thermoelectric generators (TEGs) should be designed from system integration perspectives to simultaneously improve heat transfer efficiency and system simplification as well as the robust mechanical properties. However, typical TEGs fabricated by conventional methods barely accomplish such requirements. Herein, high-quality TEGs were assembled by combining the well-flowable spherical bismuth telluride (BT) powdered precursors and selective laser melting (SLM) technology. By optimizing the electronic and phonon transport properties through defect engineering driven by 3D printing, a high figure of merit was accomplished for 1.27 (p-type) and 1.13 (n-type) in BT. This achievement is primarily attributed to the nonequilibrium solidification mechanism, which leads to the formation of multiscale defects during the 3D printing process. The introduction of these multiscale defects enables the effective scattering of wide frequency phonons, leading to a substantial reduction in lattice thermal conductivity. Meanwhile, robust mechanical properties were obtained in the printed p-type/n-type BT TE materials parallel to the building direction (BD) with a compressive strength reaching 257/250 MPa by employing the fine grain structure and the high density of nanotwins introduced during the SLM process. A well shape-controllable and high-performance TEG was designed using 3D-printed BT half-rings, and an output power of 134 mW was achieved at a temperature gradient of 38.9 °C. Our study opens a new route for the great potential of TE materials based on standard commercial SLM 3D printing technology for low-grade waste heat emitted from structures with heterogeneous shapes.

Broad Temperature Plateau for High Thermoelectric Properties of n-Type Bi2Te2.7Se0.3 by 3D Printing-Driven Defect Engineering.

High-energy-conversion Bi2Te3-based thermoelectric generators (TEGs) are needed to ensure that the assembled material has a high value of average figure of merit (ZTave). However, the inferior ZTave of the n-type leg severely restricts the large-scale applications of Bi2Te3-based TEGs. In this study, we achieved and reported a high peak ZT (1.33) of three-dimensional (3D)-printing n-type Bi2Te2.7Se0.3. In addition, a superior ZTave of 1.23 at a temperature ranging from 300 to 500 K was achieved. The high value of ZTave was obtained by synergistically optimizing the electronic- and phonon-transport properties using the 3D-printing-driven defect engineering. The nonequilibrium solidification mechanism facilitated the multiscale defects formed during the 3D-printed process. Among the defects formed, the nanotwins triggered the energy-filtering effect, thus enhancing the Seebeck coefficient at a temperature range of 300-500 K. The effective scattering of wide-frequency phonons by multiscale defects reduced the lattice thermal conductivity close to the theoretical minimum of ∼0.35 W m-1 k-1. Given the advantages of 3D printing in freeform device shapes, we assembled and measured bionic honeycomb-shaped single-leg TEGs, exhibiting a record-high energy conversion efficiency (10.2%). This work demonstrates the great potential of defect engineering driven by selective laser melting 3D-printing technology for the rational design of advanced n-type Bi2Te2.7Se0.3 thermoelectric material.

Development and validation of an MRI-based nomogram for the preoperative prediction of tumor mutational burden in lower-grade gliomas.

Background: High tumor mutational burden (TMB) is an emerging biomarker of sensitivity to immune checkpoint inhibitors. In this study, we aimed to determine the value of magnetic resonance (MR)-based preoperative nomogram in predicting TMB status in lower-grade glioma (LGG) patients. Methods: Overall survival (OS) data were derived from The Cancer Genome Atlas (TCGA) and then analyzed by using the Kaplan-Meier method and time-dependent receiver operating characteristic (tdROC) analysis. The magnetic resonance imaging (MRI) data of 168 subjects obtained from The Cancer Imaging Archive (TCIA) were retrospectively analyzed. The correlation was explored by univariate and multivariate regression analyses. Finally, we performed tenfold cross validation. TMB values were retrieved from the supplementary information of a previously published article. Results: The high TMB subtype was associated with the shortest median OS (high vs. low: 50.9 vs. 95.6 months, P<0.05). The tdROC for the high-TMB tumors was 74% (95% CI: 61-86%) for survival at 12 months, and 71% (95% CI: 60-82%) for survival at 24 months. Multivariate logistic regression analysis confirmed that three risk factors [extranodular growth: odds ratio (OR): 8.367, 95% CI: 3.153-22.199, P<0.01; length-width ratio ≥ median: OR: 1.947, 95% CI: 1.025-3.697, P<0.05; frontal lobe: OR: 0.455, 95% CI: 0.229-0.903, P<0.05] were significant independent predictors of high-TMB tumors. The nomogram showed good calibration and discrimination. This model had an area under the curve (AUC) of 0.736 (95% CI: 0.655-0.817). Decision curve analysis (DCA) demonstrated that the nomogram was clinically useful. The average accuracy of the tenfold cross validation was 71.6% for high-TMB tumors. Conclusions: Our results indicated that a distinct OS disadvantage was associated with the high TMB group. In addition, extranodular growth, nonfrontal lobe tumors and length-width ratio ≥ median can be conveniently used to facilitate the prediction of high-TMB tumors.

Correlation between body mass index and two-stage revision failure of periprosthetic joint infection following total joint arthroplasty: A systematic review and meta-analysis.

Background: Although the correlation between body mass index (BMI) and two-stage revision failure of periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) have been frequently reported, the results remain controversial. Therefore, the correlation between them was systematically evaluated and meta-classified in this study. Methods: Literature on the correlation between BMI and two-stage revision failure of PJI following TJA was retrieved in PubMed, Embase and Cochrane Library due May 2020. Stata 13.0 software and Cochrane Collaboration Review Manager software (RevMan version 5.3) were applied to data synthesis, subgroup analysis, analyses of publication bias, and sensitivity. Results: A total of 15 observational studies included 1267 patients, of which 15 studies were included in systematic review and 11 studies in meta-analysis. Eight studies found a correlation between BMI and two-stage revision failure of PJI following TJA, but seven other studies found no correlation. Meta-analysis found that the risk of two-stage revision failure of PJI following TJA significantly boosted by 3.53 times in patients with BMI ≥ 30 kg/m2 (OR = 3.53; 95% CI = 1.63-7.64 for the BMI ≥ 30 kg/m2 vs. BMI < 30 kg/m2) and the risk of two-stage revision failure of PJI following TJA significantly increased by 2.92 times in patients with BMI ≥ 40 kg/m2 (OR = 2.92; 95%CI = 1.06-8.03 for the BMI ≥ 40 kg/m2 vs. BMI < 30 kg/m2). The subgroup analysis showed that significant association was observed among the studies performed in TKA (OR = 3.63; 95% CI = 2.27-5.82), but not among those conducted in THA (OR = 3.06; 95% CI = 0.42-22.19). A significant association remained consistent, as indicated by sensitivity analyses. Because there are too few studies that can be combined in the included studies, Egger's and Begg's tests were not performed. Conclusion: Meta-analysis suggests that the risk of two-stage revision failure of PJI following TJA significantly boosted in obese patients. However, because there may be publication bias of this study, combined overall systematically evaluated and meta-analysis results, we cannot yet conclude that BMI is associated with two-stage revision failure of PJI following TJA.

An emerging potential therapeutic target for osteoporosis: LncRNA H19/miR-29a-3p axis.

Osteoporosis (OP) is a complex systemic disease characterized by a loss of bone density, leading to bone fragility and an increase risk of fractures of the hip, spine and wrist. The clinical therapeutic effect is still far from satisfactory. Thus, further studies are urgently needed to explore the pathogenesis of OP. In this study, our aim is to explore the underlying molecular mechanism of lncRNA H19/miR-29a-3p axis for regulating of inflammation, proliferation and apoptosis in OP. The expression of lncRNA H19 was significantly upregulated in OP samples compared with the health control. Subsequently, we found that miR-29a-3p is the target of lncRNA H19 in OP. Furthermore, the knockdown of lncRNA H19 was validated to promote the expression of pro-inflammatory mediators, repress cell proliferation and inhibit cell apoptosis in vitro. Moreover, the modulating effects of lncRNA-H19 on the expressions of pro-inflammatory mediators, cell proliferation and apoptosis in vitro were diminished after co-transfecting with miR-29a-3p inhibitor and siRNA-H19. Thus, we concluded that lncRNA H19/miR-29a-3p axis was involved in the development of OP. This study might provide a better understanding of OP development and a potential therapeutic target for OP intervention.