基于问题导向的物理化学实验项目设计与改进——以液体表面张力测定为例

以日常生活现象(洗衣时的白色絮凝物)为切入点,通过问题导向,引导学生自主设计实验。将表面张力的测量融入探究生活现象背后化学原理的过程中,综合运用多种技术手段,建立“发现问题-探索实践-回归课本”的探索型实验模式,从而巩固学生对胶体与界面化学知识点的理解。改进后的实验内容更丰富,挑战度更高,综合性更强,趣味性更浓,有利于培养学生分析和解决问题的能力,能更好地培养学生的探究性思维。此外,本实验安全性较高,易于操作,对设备无特殊要求,非常适合本科教学实验。

Capacity and Flexibility Improvement of Traffic Aggregation for Fixed 5G:Key Enabling Technologies,Challenges and Trends

As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service experience.With the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and back-haul.Optical access networks would play an important role in F5G to support radio access network and fixed access network.Low-latency PON is a key for cost effective-haul traffic aggregation.In terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple architecture.The fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s phase.In access network,the flexibility and low latency are the two key factors affecting service experience.In this article,we review the evolution of PONs and the challenges of current PONs in detail.We analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU communications.Finally,we discuss the developing trends of future optical access networks.

A highly selective fluorescent probe for real-time imaging of UDP-glucuronosyltransferase 1A8 in living cells and tissues

Uridine diphosphate(UDP)-glucuronosyltransferases(UGTs)are enzymes involved in the biotransformation of important endogenous compounds such as steroids,bile acids,and hormones as well as exogenous substances including drugs,environmental toxicants,and carcinogens.Here,a novel fluorescent probe BDMP was developed based on boron-dipyrromethene(BODIPY)with high sensitivity for the detection of UGT1A8.The glucuronidation of BDMP not only exhibited a redemission wavelength(lex/lem=500/580 nm),but also displayed an excellent UGT1A8-dependent fluorescence signal with a good linear relationship with UGT1A8 concentration.Based on this perfect biocompatibility and cell permeability,BDMP was successfully used to image endogenous UGT1A8 in human cancer cell lines(LoVo and HCT15)in real time.In addition,BDMP could also be used to visualize UGT1A8 in tumor tissues.These results suggested that BDMP is a promising molecular tool for the investigation of UGT1A8-mediated physiological function in humans.

The unconventional prefoldin RPB5 interactor mediates the gravitropic response by modulating cytoskeleton organization and auxin transport in Arabidopsis

Gravity-induced root curvature involves the asymmetric distribution of the phytohormone auxin.This response depends on the concerted activities of the auxin transporters such as PIN-FORMED(PIN)proteins for auxin efflux and AUXIN RESISTANT 1(AUX1)for auxin influx.However,how the auxin gradient is established remains elusive.Here we identified a new mutant with a short root,strong auxin distribution in the lateral root cap and an impaired gravitropic response.The causal gene encoded an Arabidopsis homolog of the human unconventional prefoldin RPB5 interactor(URI).At URI interacted with prefoldin 2(PFD2)and PFD6,twoβ-type PFD members that modulate actin and tubulin patterning in roots.The auxin reporter DR5_(rev):GFP showed that asymmetric auxin redistribution after gravistimulation is disordered in aturi-1 root tips.Treatment with the endomembrane protein trafficking inhibitor brefeldin A indicated that recycling of the auxin transporter PIN2 is disrupted in aturi-1 roots as well as in pfd mutants.We propose that At URI cooperates with PFDs to recycle PIN2and modulate auxin distribution.

CDC48B facilitates the intercellular trafficking of SHORT-ROOT during radial patterning in roots

CELL DIVISION CONTROL PROTEIN48(CDC48)is essential for membrane fusion,protein degradation,and other cellular processes.Here,we revealed the crucial role of CDC48B in regulating periclinal cell division in roots by analyzing the recessive gen1 mutant.We identified the GEN1 gene through map-based cloning and verified that GEN1 encodes CDC48B.gen1 showed severely inhibited root growth,increased periclinal cell division in the endodermis,defective middle cortex(MC)formation,and altered ground tissue patterning in roots.Consistent with these phenotypes,CYCLIND 6;1(CYCD6;1),a periclinal cell division marker,was upregulated in gen1 compared to Col-0.The ratio of SHR_(pro):SHR-GFP fluorescence in pre-dividing nuclei versus the adjacent stele decreased by 33%in gen1,indicating that the trafficking of SHORT-ROOT(SHR)decreased in gen1 when endodermal cells started to divide.These findings suggest that the loss of function of CDC48B inhibits the intercellular trafficking of SHR from the stele to the endodermis,thereby decreasing SHR accumulation in the endodermis.These findings shed light on the crucial role of CDC48B in regulating periclinal cell division in roots.