由于其高容量和丰富的资源,过渡金属硫化物(TMS)已被证明是钾离子电池具有吸引力的负极材料之一.然而,TMS通常受到导电性差和体积膨胀大的限制,可能导致结构不稳定和电池循环性能差.本工作通过将超小Cu_(2)S纳米粒子植入碳纳米线(Cu_(2)S@C NWs),显著减轻了纳米粒子聚集和有害的结构退化.与传统的Cu_(2)S颗粒相比,每根纳米线的体积变化都得到了有效调节,这极大地改善了形态完整性,从而显著提高了循环寿命.正如预期的那样,Cu_(2)S@C NW负极可提供391.1 mA h g^(-1)的大可逆容量,在5 A g^(-1)时具有118.1 mA h g^(-1)的出色倍率性能,以及在2 A g^(-1)下经过500次循环后77.2%的高容量保持率.此外,当Cu_(2)S@C NW负极与KVP04F/CNTs正极组装形成钾离子全电池时,在50 mA g^(-1)下循环100次后显示出110.8 mA h g^(-1)的良好放电容量.这种纳米颗粒阻聚策略拓宽了纳米工程的视野,以释放嵌脱钾引起的应力,并促进钾离子电池高效负极的进一步发展.
目的探讨食管闭锁术后经鼻胃管进行高能量密度的早期肠内营养模式对术后恢复的影响。方法收集2016年1月至2022年12月在天津市儿童医院一期食管吻合手术治疗的Ⅲb型先天性食管闭锁36例患儿的资料,所有患儿均于术后早期经鼻胃管进行肠内营养(enteral nutrition,EN)。根据所使用配方奶能量密度分为两组:一组为早期微量EN组17例,其中男11例,女6例,胎龄为(38.8±1.3)周,出生体重为(2.6±0.3)kg,术后早期给予深度水解配方奶微量喂养;另一组早期强化EN组19例,其中男13例,女6例,胎龄为(38.5±1.8)周,出生体重为(2.8±0.4)kg,术后早期给予高能量密度深度水解配方奶喂养。两组均根据胃肠道耐受情况,逐步增加肠内营养量,最终过渡至完全经口喂养。采用IBM SPSS Statistics 26软件处理所有数据,符合正态分布的定量资料用独立样本t检验,非正态分布用非参数检验。结果两组在术前一般指标、手术方式、喂养不耐受、术后首次排便时间、术后14 d血清前白蛋白水平及术后1个月年龄别体重Z值(weight for age z score,WAZ)方面差异无统计学意义(P>0.05);早期强化EN组术后7 d血清前白蛋白水平、日均体重增长、达到全肠内营养时间、住院时长、住院总费用方面明显优于早期微量EN组,差异均有统计学意义(P<0.05)。结论新生儿食管闭锁术后早期高能量密度的肠内营养有助于改善围手术期营养状态,缩短住院时间及减少医疗花费,值得临床推广。
Following the 2011 Fukushima Daiichi nuclear catastrophe, there has been a significant surge in interest towards innovative materials capable of enhancing the safety, performance, and efficiency of nuclear reactors. T...
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Following the 2011 Fukushima Daiichi nuclear catastrophe, there has been a significant surge in interest towards innovative materials capable of enhancing the safety, performance, and efficiency of nuclear reactors. This study introduces a new class of layered ternary compounds, specifically (UC) n Si 3 C 2 (n = 1,2), and derived two-dimensional (2D) U 2 C, discovered through first-principles calculations. We predict the electronic, mechanical, and thermodynamic properties of these compounds within the PBE and PBE + U frameworks, with a comparative analysis of the (UC) n Al 3 C 2 (n = 1,2) series. Our findings reveal that the USi 3 C 3 and U 2 Si 3 C 4 compounds exhibit mechanical and dynamic stabilities, suggesting their potential for experimental synthesis under specific conditions. These compounds demonstrate superior mechanical and thermal properties as nuclear fuels, including higher elastic moduli and improved ductility compared to (UC) n Al 3 C 2 compounds. The mechanical and dynamical stabilities of 2D U 2 C are confirmed, and the calculated thermal conductivity and mechanical properties position it as a promising candidate for high-performance nuclear fuel applications. We anticipate that the present work will bolster future experimental endeavors and help explore the practical applications of these novel materials in future nuclear systems.
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