疏水缔合聚丙烯酰胺水凝胶的研制及自愈机理

采用疏水缔合的物理交联方式,将十二烷基硫酸钠(SDS)、氯化钠(NaCl)、甲基丙烯酸十八烷酯(SMA)反应所得的可聚合胶束与丙烯酰胺(AM)共聚缩合,制备出具有自愈合特性的聚丙烯酰胺(PAM)水凝胶,采用动态光散射测试、扫描电镜、红外光谱、热分析等表征手段对其理化性能进行了研究,并对其自愈合机理进行分析探讨。结果表明,制备所得PAM水凝胶含水率可达95%左右;SMA含量对PAM水凝胶含水率影响不明显,但SMA含量越高,所得水凝胶网络结构越紧密,孔隙尺寸越小,抗压强度、韧性和自愈率越高,但拉伸强度却随之下降。优选出的最佳工艺参数为:7%g/mL SDS溶液加入0.9 mol/L NaCl溶液中所得胶束尺寸最大,且疏水单体SMA的摩尔分数为AM单体的2%时,所得PAM水凝胶的抗拉强度和自愈率均最佳。

Spectral Efficiency and Power Allocation for Mixed-ADC Massive MIMO System

This paper investigates the achievable uplink spectral efficiency(SE) of a massive multi-input multi-output(MIMO) system with a mixed analog-to-digital converter(ADC) receiver architecture, in which some antennas are equipped with full-resolution ADCs while others are deployed with low-resolution ADCs. We derive the theoretical results and corresponding approximate expressions of the achievable SE in multi-cell systems with maximum ratio combining(MRC) detector and in single-cell systems with zero-forcing(ZF) detector. Based on approximated results, the effects of physical parameters, including the transmit power, the number of antennas, the proportion of full-resolution ADCs and the quantization precision of the low-resolution ADCs on the achievable SE are revealed. Furthermore, we propose the power allocation algorithms based on the lower bound and upper bound of approximate achievable SE. Our results show that the total achievable SE improves by increasing the number of BS antennas, the signal-to-noise ratio(SNR), and the quantization precision. Results showcase that proposed power allocation algorithms remarkably improve the total achievable SE comparing to the equal power allocation algorithm, which verifies the effectiveness of our proposed schemes.

AG Channel Measurements and Characteristics Analysis in Hilly Scenarios for 6G UAV Communications

As an important part of sixth generation(6G)integrated space-air-ground-sea networks,unmanned aerial vehicle(UAV)communications have aroused great attention and one of its typical application scenarios is the hilly environments.The related UAV air-ground(AG)channel characteristics analysis is crucial for system design and network evaluation of future UAV communications in hilly scenarios.In this paper,a recently conducted channel measurements campaign in a hilly scenario is presented,which is conducted at the center frequencies of 2.585 GHz and 3.5 GHz for different flight trajectories.Based on the measurement data,some key channel characteristics are analyzed,including path loss(PL),shadow fading(SF),Rician K-factor,root mean square(RMS)delay spread(DS),and temporal auto-correlation function(ACF).Finally,the comparison of typical channel characteristics under circular and straight trajectories is given.The related results can provide a theoretical reference for constructing future UAV communication system in hilly scenarios.

内镜人工智能诊断辅助系统对胃局灶性病变检出的应用(含视频)

目的构建一个基于YOLO v3算法的实时人工智能诊断辅助系统,并评估其在胃镜检查中对胃局灶性病变检出的能力。方法回顾性收集武汉大学人民医院消化内镜中心2019年6—11月胃镜检查的白光内镜图像5488张(有、无胃局灶性病变的图像分别为2733张、2755张)及2020年5—6月期间92例行胃镜检查的受试者视频资料中288168个清晰胃帧用于人工智能辅助系统测试;前瞻性收集2020年7月6日—11月27日及2021年5月6日—8月2日于武汉大学人民医院消化内镜中心接受胃镜检查的3997例受检者的视频资料用于评估人工智能辅助系统在实际临床应用中的性能。当人工智能辅助系统识别到异常病灶时,以蓝色方框圈出病灶进行提示。对人工智能辅助系统识别胃局灶性病变的能力及其出现假阳性和假阴性的频率和原因进行统计分析。结果图像测试集中,人工智能辅助系统“提示病灶”的准确率、灵敏度、特异度、阳性预测值及阴性预测值分别为92.3%(5064/5488)、95.0%(2597/2733)、89.5%(2467/2755)、90.0%(2597/2885)和94.8%(2467/2603)。视频测试集中,人工智能辅助系统“提示病灶”的准确率、灵敏度、特异度、阳性预测值及阴性预测值分别为95.4%(274792/288168)、95.2%(109727/115287)、95.5%(165065/172881)、93.4%(109727/117543)和96.7%(165065/170625)。临床应用中,人工智能辅助系统对胃局灶性病变的检出率为93.0%(6830/7344)。共漏检胃局灶性病变514处,主要原因为微小糜烂灶(48.8%,251/514)、微小黄斑瘤(22.8%,117/514)和小息肉(21.4%,110/514)。平均每例上消化道内镜检查中,人工智能辅助系统的假阳性个数为2(1,4)个,主要原因为正常黏膜皱襞(50.2%,5635/11225)、气泡和黏液(35.0%,3928/11225)、胃底液体(9.1%,1021/11225)。结论在胃镜检查过程中应用人工智能辅助系统有助于胃局灶性病变的检出。

TBC1D15 deficiency protects against doxorubicin cardiotoxicity via inhibiting DNAPKcs cytosolic retention and DNA damage

Clinical application of doxorubicin(DOX)is heavily hindered by DOX cardiotoxicity.Several theories were postulated for DOX cardiotoxicity including DNA damage and DNA damage response(DDR),although the mechanism(s)involved remains to be elucidated.This study evaluated the potential role of TBC domain family member 15(TBC1D15)in DOX cardiotoxicity.Tamoxifen-induced cardiac-specific Tbcldi5 knockout(Tbcldi5^(CKO))or Tbcldi5 knockin(Tbcldi5^(CKI))male mice were challenged with a single dose of DOx prior to cardiac assessment 1 week or 4 weeks following DOX challenge.Adenoviruses encoding TBC1D15 or containing shRNA targeting Tbcld15 were used for Tbcld15 overexpression or knockdown in isolated primary mouse cardiomyocytes.Our results re-vealed that DOX evoked upregulation of TBC1D15 with compromised myocardial function and overt mortality,the effects of which were ameliorated and accentuated by Tbcldi5 deletion and Tbcld15 overexpression,respectively.DOX overtly evoked apoptotic cell death,the effect of which was alleviated and exacerbated by Tbcld15 knockout and overexpression,respectively.Meanwhile,DOX provoked mitochondrial membrane potential collapse,oxidative stress and DNA damage,the effects of which were mitigated and exacerbated by Tbcld15 knockdown and overexpression,respectively.Further scrutiny revealed that TBC1D15 fostered cytosolic accumulation of the cardinal DDR element DNA-dependent protein kinase catalytic subunit(DNA-PKcs).Liquid chromatography-tandem mass spectrometry and coimmunoprecipitation denoted an interaction between TBCID15 and DNA-PKcs at the segment 594-624 of TBC1D15.Moreover,overexpression of TBC1D15 mutant(A594-624,deletion of segment 594-624)failed to elicit accentuation of DOX-induced cytosolic retention of DNA-PKcs,DNA damage and cardiomyocyte apoptosis by TBC1D15 wild type.However,Tbcld15 deletion ameliorated DOXinduced cardiomyocyte contractile anomalies,apoptosis,mitochondrial anomalies,DNA damage and cytosolic DNA-PKcs accumulation,which were canceled off by DNA-PKcs inhibition or ATM activation.Taken together,our findings denoted a pivotal role for TBCID15 in DOX-induced DNA damage,mitochondrial injury,and apoptosis possibly through binding with DNA-PKcs and thus gate-keeping its cytosolic retention,a route to accentuation of cardiac contractile dysfunction in DOX-induced cardiotoxicity.

Dual-responsive nanoparticles with transformable shape and reversible charge for amplified chemo-photodynamic therapy of breast cancer

Herein, we designed a dual-response shape transformation and charge reversal strategy with chemo-photodynamic therapy to improve the blood circulation time, tumor penetration and retention,which finally enhanced the anti-tumor effect. In the system, hydrophobic photosensitizer chlorin e6(Ce6), hydrophilic chemotherapeutic drug berberrubine(BBR) and matrix metalloproteinase-2(MMP-2) response peptide(PLGVRKLVFF) were coupled by linkers to form a linear triblock molecule BBR-PLGVRKLVFF-Ce6(BPC), which can self-assemble into nanoparticles. Then, positively charged BPC and polyethylene glycol-histidine(PEG-His) were mixed to form PEG-His@BPC with negative surface charge and long blood circulation time. Due to the acidic tumor microenvironment, the PEG shell was detached from PEG-His@BPC attributing to protonation of the histidine, which achieved charge reversal, size reduction and enhanced tumor penetration. At the same time, enzyme cutting site was exposed, and the spherical nanoparticles could transform into nanofibers following the enzymolysis by MMP-2, while BBR was released to kill tumors by inducing apoptosis. Compared with original nanoparticles, the nanofibers with photosensitizer Ce6 retained within tumor site for a longer time. Collectively,we provided a good example to fully use the intrinsic properties of different drugs and linkers to construct tumor microenvironment-responsive charge reversal and shape transformable nanoparticles with synergistic antitumor effect.

A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process

Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitablemicroenvironments mimicked the extracellular matrices for desired cellular interactions and to providesupports for the formation of new tissues. In this work, a kind of slightly soluble bioactiveceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix,a novel L-lactide modified AKT/poly (lactic-co-glycolic acid) (m-AKT/PLGA) composite scaffold wasfabricated via a solvent casting-particulate leaching method improved by solvent self-proliferatingprocess. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellularbehaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited threedimensionalporous networks, in which homogenously distributed cavities in size of 300–400 lmwere interconnected by some smaller holes in a size of 100–200 lm. Meanwhile, the mechanicalstructure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic productsreleased by m-AKT could neutralize the acidic degradation products of PLGA, and the apatitemineralizationability of scaffolds could be largely improved. More valuably, significant promotionson adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied thecalcium, magnesium and especially silidous ions released sustainably from composite scaffoldscould regulate the behaviors of osteogenesis-related cells.

A Model-Driven Deep Learning Network for Quantized GFDM Receiver

Low-resolution analog-to-digital converter(ADC)is a promising solution to reduce hardware cost and power consumption in generalized frequency division multiplexing(GFDM)systems.The severe nonlinear distortion of ADCs and the non-orthogonality of GFDM make receiver design a great challenge.In this paper,we propose a novel model-driven receiver architecture for GFDM with low-resolution ADCs.Orthogonal approximate message passing(OAMP)framework is combined with the classical linear estimator in this work to create a robust iterative receiver for GFDM systems with low-precision ADCs.The corresponding model-driven network is organized based on the proposed novel iterative algorithm according to the procedures of the receiver.The network of OAMP can reduce the gap between the approximate algorithm and the Bayesian optimal result due to the information loss of ADCs.The signal flow of the neural network is designed by unfolding the iterative algorithms for channel estimation and data detection.Numerical results are provided to show that the proposed OAMP-based receiver algorithm outperforms traditional receivers and the model-driven network can further improve the system performance on the basis of the corresponding novel algorithm.