人体消化道内微机电系统线圈耦合系数分析

在人体消化道微机电系统无线能量传输系统中,线圈间的耦合程度是影响传输效率的关键因素之一.本文对空间任意位置的两个线圈建立耦合模型,提出了一种计算线圈耦合系数的方法,分析了轴向偏移、径向偏移、角度偏移对耦合程度的影响,与实验结果吻合较好.最后利用这种方法,比较分析了能量传输系统中发射线圈的两种布置方式.     

微卫星不稳定性在膀胱癌复发诊断中的价值

背景与目的:评估尿脱落细胞中微卫星不稳定性(Microsatelliteinstability,MSI)在膀胱癌复发诊断中的价值及可能的临床意义。材料与方法:对60份膀胱癌术后随访尿液标本及20份正常对照标本进行微卫星不稳定性的检测。分析参数包括有无血尿、肿瘤数目、大小、WHO分级及5个微卫星位点标志物。结果:20例复发者中17例MSI阳性(85.00%),且15例为血尿标本,检测术后随访者尿脱落细胞中MSI诊断膀胱癌复发的敏感性、特异性及阳性预报值分别为85.00%、82.50%及83.33%,MSI与肿瘤分级间无明显相关性。结论:MSI可以作为膀胱癌术后随访病人尤其伴有血尿者监测肿瘤复发的良好标志物。     

1450nm半导体激光联合强脉冲光治疗中度寻常性痤疮的临床观察

目的:观察1 450nm半导体激光联合强脉冲光治疗中度寻常性痤疮的疗效及安全性。方法:选取中度寻常性痤疮患者160例,按照就诊顺序随机分为试验组与对照组,试验组:80例,采用1 450nm半导体激光联合强脉冲光治疗;对照组:80例,使用1 450nm半导体激光治疗。治疗4次后评估两组的疗效,并评估两组患者的满意度。结果:试验组与对照组治疗4次后有效率分别为95.00%和82.50%;试验组和对照组满意度分别为82.50%和68.75%,试验组有效率比对照组好,满意度试验组比对照组高,两组比较差异有统计学意义(P<0.05)。结论:1 450nm半导体激光联合强脉冲光治疗中度痤疮短期疗效好,患者满意度高,不良反应少,并且长期疗效理想,可供临床选用。     

甲状旁腺病变的超声诊断及多种影像学对比分析

评价超声在甲状旁腺疾病诊断中的价值及多种影像学检查技术在甲状旁腺疾病诊断中的对比分析。方法回顾性分析于我院行甲状旁腺手术切除患者94例,共104个病灶。观察病变的声像图特征,对比分析多种影像学检查结果。结果不同甲状旁腺病变的超声声像图特征具有差异性,超声诊断甲状旁腺病变的敏感度为82.69%(86/104),对于直径1cm的病变,超声诊断的敏感度明显高于其他检查单独使用,而对于合并甲状腺结节的病变超声的敏感度低于核素显像及超声联合核素检查(P均0.05)。结论超声可作为甲状旁腺病变诊断的首选检查方法,联合运用各种影像学检查,可更好地进行病变的术前定位及诊断。     

“J”状塑型双腔气管导管插管操作对成功率及术后声音嘶哑、咽喉痛的影响

目的 观察双腔气管导管(double-lumen endotracheal tube,DLT)塑型对插管成功率及术后声音嘶哑(声嘶)、咽喉痛的影响,从而为寻求更好的DLT塑型插管提供依据. 方法 择期全身麻醉下行胸科手术患者160例,美国麻醉医师协会(ASA)分级Ⅰ～Ⅲ级,参照随机数字表法分成DLT插管塑型组和非塑型组(每组80例),两组根据左右DLT插管各分为两组(A、B、C、D组,每组40例),又根据性别再各分为两个亚组(A1、A2、B1、B2、C1、C2、D1、D2组,每组20例).两组均采用经口明视气管插管,塑型组采用塑成“J”状的DLT进行插管,非塑型组采用未经塑型保留原有弯度的DLT进行插管.观察DLT插管时间、插管尝试次数及插反情况,患者术后声嘶、咽喉痛发生率及严重程度. 结果 塑型组插管时间[(154±6)s]明显短于非塑型组[(185±13)s](P＜0.05);塑型组插管尝试次数[(1.4±0.4)次]明显少于非塑型组[(1.7±0.8)次](P＜0.05);塑型组插反情况(3次)明显比非塑型组少(11次)(P＜0.05),且与性别无关,但左DLT比右DLT易于插反(P＜0.05).患者术后声嘶发生率塑型组(15/80)明显低于非塑型组(33/80)(P＜0.05);患者术后咽喉痛发生率塑型组(15/80)明显低于非塑型组(31/80) (P＜0.05),且与性别有关,女性较男性术后易发生声嘶、咽喉痛. 结论 “J”状DLT塑型插管成功率高、刺激小,可降低患者术后声嘶、咽喉痛发生率,具有一定的临床推广意义.     

Quantitative Multimodal Evaluation of Passaging Human Neural Crest Stem Cells for Peripheral Nerve Regeneration

Peripheral nerve injury is a major burden to societies worldwide, however, current therapy options (e.g. autologous nerve grafts) are unable to produce satisfactory outcomes. Many studies have shown that stem cell transplantation holds great potential for peripheral nerve repair, and human neural crest stem cells (hNCSCs), which give rise to a variety of tissues in the peripheral nervous system, are particularly promising. NCSCs are one of the best candidates for clinical translation, however, to ensure the viability and quality of NCSCs for research and clinical use, the effect of in vitro cell passaging on therapeutic effects needs be evaluated given that passaging is required to expand NCSCs to meet the demands of transplantation in preclinical research and clinical trials. To date, no study has investigated the quality of NCSCs past the 5th passage in vivo. In this study, we employed a multimodal evaluation system to investigate changes in outcomes between transplantation with 5th (p5) and 6th passage (p6) NCSCs in a 15 mm rat sciatic nerve injury and repair model. Using CatWalk gait analysis, gastrocnemius muscle index, electrophysiology, immunohistochemistry, and histomorphometric analysis, we showed that p6 NCSCs demonstrated decreased cell survival, Schwann-cell differentiation, axonal growth, and functional outcomes compared to p5 NCSCs (all p?<?0.05). In conclusion, p6 NCSCs showed significantly reduced therapeutic efficacy compared to p5 NCSCs for peripheral nerve regeneration.     

Unusual Mott transition in multiferroic PbCrO3

The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by “bandwidth” control or “band filling.” However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction. Here, we report a pressure-induced isostructural Mott transition in cubic perovskite PbCrO₃. At the transition pressure of ∼3 GPa, PbCrO₃ exhibits significant collapse in both lattice volume and Coulomb potential. Concurrent with the collapse, it transforms from a hybrid multiferroic insulator to a metal. For the first time to our knowledge, these findings validate the scenario conceived by Mott. Close to the Mott criticality at ∼300 K, fluctuations of the lattice and charge give rise to elastic anomalies and Laudau critical behaviors resembling the classic liquid–gas transition. The anomalously large lattice volume and Coulomb potential in the low-pressure insulating phase are largely associated with the ferroelectric distortion, which is substantially suppressed at high pressures, leading to the first-order phase transition without symmetry breaking.Early transition-metal (TM) oxides with partially filled d electrons are strongly correlated (1, 2). Such correlated systems often present exciting new physics and technologically useful electronic and magnetic properties. Mott transition, characterized by delocalization of d electrons, is an attractive phenomenon for exploring the correlated nature of electrons (2, 3). Since the early failure of band theory in the 1930s, the Coulomb repulsion (U) has been proposed to be a strong force that causes electron localization (4, 5). In such electrostatic interaction, the repulsion energy decreases with the compressed lattice because of the screening effect (5–7). Consequently, as originally predicted by Mott (5), the Mott transition is controlled by U at pressures (P).Despite several decades of intensive study, it is still challenging to experimentally validate this view of Mott transition, because U is experimentally difficult to determine, and for most correlated materials it is independent of the pressure. For the known Mott systems, they are found to be controlled by either the bandwidth [e.g., the organic compound κ-Cl (8–10) and Cr-doped V₂O₃ (11, 12)] or band filling (i.e., doping of charge carriers into the parent insulator) (2). Recently, electronic transitions have frequently been reported in late 3d TM oxides (e.g., MnO) (13–16), which are theoretically attributed to bandwidth control (15) or crystal-field splitting (17). For those oxides, a U-controlled mechanism has also been proposed by Gavriliuk et al. (14) and Gavriliuk and coworkers (18); however, the spin cross-over, instead of the screening effect, is believed to contribute to the decreased U (14, 18). Complicating matter further is that the U of (Mg_1–xFe_x)O was computed to increase with pressures (13).TM oxides with a perovskite structure (ABO₃) often exhibit intriguing structural, magnetic, and electronic properties for the study of correlated systems. Among them, PbCrO₃ is such a material that can only be synthesized at high pressures. At ambient pressure, it adopts a paramagnetic (PM), cubic structure at room temperature (T) with an anomalously large unit-cell volume and transforms to an antiferromagnetic (AFM) ground state at low temperatures (19, 20). The magnetic properties arise from unpaired 3d electrons in Cr (i.e., nominally 3d²) with a large U value of 8.28 eV (19–21). Under high pressures, an isostructural phase transition (i.e., no symmetry breaking) has recently been reported in PbCrO₃ with ∼9.8% volume reduction at ∼1.6 GPa; it is the largest volume reduction known in transition-metal oxides (22). Compared with the low-P phase, the high-P phase possesses a more “normal” unit-cell volume (see refs. 21 and 22) and a moderate U of ∼3 eV (23), suggesting a collapse of Coulomb repulsion energy at the phase transition. Because of the reduced U, the mobility of 3d electrons at high pressures is energetically more favorable, which would lead to d-electron delocalization. Apparently, this is a U-driven Mott transition in PbCrO₃ as conceived by Mott. However, to date, the electronic properties of both PbCrO₃ phases have only poorly been explored. In particular, controversial electronic states, including semiconductor (24, 25), half-metal (21), or insulator (20), have been reported for the low-P phase. Besides, the crystal structure and elastic and magnetic properties, as well as the underlying mechanism for the isostructural transition, are still unsettled issues, calling for rigorous investigation into this material.With these aims, in this work we present a comprehensive study on PbCrO₃ with a focus on the P-induced electronic transition. Our findings unveil a unique Mott transition in this perovskite and a new mechanism underlying the isostructural transition.