Controlling upconversion through interfacial energy transfer(IET):Fundamentals and applications

Photon upconversion has received substantial attention owing to its great promise in broad applications from bioimaging to other frontier fields like display,upconversion laser,information security and anticounterfeiting.A smart control and manipulation of the upconversion luminescence has always been a key topic,however,to date the most efficient mechanism for upconversion nanoparticles remains the energy transfer upconversion and recently reported energy migration mediated upconversion.Recently,we found that the interfacial energy transfer(IET) is also an efficient approach for enabling and tuning photon upconversion of lanthanide ions.Moreover,it can be used for the mechanistic understanding of the interionic interactions such as energy transfer and energy migration on the nanoscale.In this review,the recent advances of the research on the IET are summarized,the principles for designing IET process and typical examples are discussed together with its applications in both mechanistic research and frontier information security.The challenges and perspectives for future research are also commented.     

Recent progress of energy transfer and luminescence intensity boosting mechanism in Nd~(3+)-sensitized upconversion nanoparticles

Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works have been reported about biomedical applications of 980 nm excited and Yb~(3+)-sensitized upconversion nanoparticles.However,980 nm excitation wavelength overlaps with the absorption band of water molecules in the biological environment,leading to overheating effect that can induce thermal damages of normal cells and tissues.Recently,Nd~(3+)-sensitized upconversion nanoparticles which can be excited with 808 nm has been widely investigated as alternative nanoparticles that can surmount this issue of overheating effect.Even though Nd~(3+)-sensitized upconversion nanoparticles can reduce the overheating effect by 20 fold as compared to Yb~(3+)-sensitized counterpart,there are several factors that reduce the upconversion luminescence intensity.In this review article,photon energy harvesting and transferring mechanisms in Nd~(3+),Yb~(3+)and emitter ions co-doped upconversion nanoparticles under 808 nm excitation are briefly discussed.Factors that affect upconversion luminescence intensity and quantum yield of Nd~(3+)-sensitized upconversion nanoparticles are also addressed.Besides,some of the important strategies that have been recently utilized to boost upconversion luminescence intensity of Nd~(3+)sensitized upco nversion nanoparticles are tho roughly summarized.Lastly,the future challenges in the area and our perspectives are in sight.     

钠离子电池层状氧化物正极材料研究进展

钠离子电池凭借资源和成本优势在大规模储能和低速电动车领域展现出极大应用前景。层状氧化物理论容量较高且易于合成，是目前最具应用潜力的钠离子电池正极材料之一。如何改善层状氧化物正极材料的循环稳定性并提升其能量密度是当前的科学前沿问题。首先，综述了层状氧化物正极材料的几种典型改性方法，从组分设计的角度，探讨了不同掺杂元素、不同掺杂位点对材料容量和循环寿命的影响，阐述了利用阴离子反应提供额外容量的基本原理，概述了提高阴离子氧化还原可逆性的掺杂策略；从结构设计的角度，介绍了复合相材料的制备、微观结构的设计和调控等方向的最新进展；从表面设计的角度，讨论了金属氧化物、磷酸盐等作为包覆层对改善材料稳定性和倍率性能的作用机制。最后，总结了层状氧化物储钠正极材料现阶段面临的挑战，并对其未来的发展方向进行了展望，提出了新的研究思路。      

Polyhydroxyalkanoates, biopolyesters from renewable resources: physiological and engineering aspects

Polyhdroxyalkanoates (PHAs), stored as bacterial reserve materials for carbon and energy, are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials. PHAs can be produced under controlled conditions by biotechnological processes. By varying the producing strains, substrates and cosubstrates, a number of polyesters can be synthesized which differ in monomer composition. By this means, PHAs with tailored interesting physical features can be produced. All of them are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. After a historical review, possibilities for the synthesis of novel PHAs applying different micro-organisms are discussed, and pathways of PHA synthesis and degradation are shown in detail for important PHA producers. This is followed by a discussion of the physiological role of the accumulation product in different micro-organisms. Detection, analysis, and extraction methods of PHAs from microbial biomass are shown, in addition to methods for polyester characterization. Strategies for PHA production under discontinuous and continuous regimes are discussed in detail in addition to the use of different cheap carbon sources from the point of view of different PHA producing strains. An outlook on PHA production by transgenic plants closes the review.     

二维过渡金属碳化物/碳氮化物（MXene）的稳定性及改进方法

二维（2D）过渡金属碳化物/碳氮化物(Mxene)材料，因其良好的亲水性、导电性、柔韧性以及高赝电容等特性，在储能、海水淡化、催化、电磁干扰屏蔽、透明导电薄膜等领域有着巨大的应用潜力。然而，由于MXene材料中活性过渡金属、表面官能团以及结构缺陷的存在，使其在无保护的环境中（含有水、氧等）很容易被氧化，导致稳定性较差。MXene材料的氧化破坏了其片状结构，降低了其电导率，限制了其更广泛的应用。本文简要介绍了MXene的结构和合成方法；综述了MXene在不同条件下不稳定的机理，即表面官能团和周围介质发生氧化反应；并从储存条件、合成方法、气氛热处理、表面电性修饰、掺杂等方面讨论了提高MXene稳定性的方法。      

Tunable electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_x)_2Si_2O_7:Ce scintillator by adjusting La/Gd ratio

Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_2 Si_2 O_7:Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5 d_1 level of Ce~(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_x)_2 Si_2 O_7:Ce scintillator by adjusting La/Gd ratio.     

卤化物钙钛矿量子点0D-2D混合维度异质结构光探测器的研究进展及挑战

综述了多晶卤化物钙钛矿薄膜的局限性, 卤化物钙钛矿量子点的基本光学性质和制备方法, 以及在光电探测器方面的器件结构研究进展, 并重点介绍了应用在0D-2D混合维度异质结基光电晶体管器件的突破, 包括界面载流子行为和高性能光探测器的构建.最后, 总结了卤化物钙钛矿量子点作为未来商业化应用的光电子器件和电子器件的候选材料所面临的主要问题和挑战, 譬如化学不稳定性、铅毒性问题、量子点与其他材料间界面高效电荷传输等问题, 并提出了解决思路和方法.这为设计和推进高性能、高稳定性卤化物钙钛矿量子点基光电功能化器件的商业化应用指明了方向.      

纳米稀土发光材料的研究进展

概述了纳米稀土发光材料的研究进展 ,着重研究了纳米稀土发光材料的制备方法、结构与性能之间的关系。光谱学的研究主要集中在发射光谱、发光强度、荧光寿命和浓度猝灭等方面。并对该类材料的应用及发展前景进行了探讨及展望     

图像分割评估方法在显微图像分析中的应用

图像分割是计算机视觉领域中的重要分支,旨在将图像分成若干个特定的、具有独特性质的区域。随着计算机硬件计算能力的提高和计算方法的进步,大量基于不同理论的图像分割算法获得了长足的发展。因而选择合适的评估方法对分割结果的准确性和适用性进行综合评估,从而选择最优分割算法,成为图像分割研究中的必要环节。在综述14种图像分割评估指标的基础上,将其分成基于像素的评估方法、基于类内重合度的评估方法、基于边界的评估方法、基于聚类的评估方法和基于实例的评估方法五大类。在材料显微图像分析的应用背景下,通过实验讨论了不同分割方法和不同典型噪声在不同评估方法中的表现。最终,讨论了各种评估方法的优势和适用性。      

Luminescence tuning of Ce~(3+),Pr~(3+) activated(Y,Gd)AGG system by band gap engineering and energy transfer

Tuning of phosphor luminescence properties,including the emission energy/intensity and thermal stability,is an important way to develop superior luminescent materials for diverse applications.In this work,we discuss the effect of band gap engineering and energy transfer on the luminescence properties of Ce~(3+)or Pr~(3+) doped(Y,Gd)AGG systems,and analyze the underlying reasons for their different phenomena.By using VUV-UV excitation spectra and constructing VRBE schemes,the changes of host band structure,5 d excited level energies and emission thermal stability of Ce~(3+)and Pr~(3+) with the incorporation of Gd~(3+)ions were studied.In addition,the energy transfer dynamics was also investigated in terms of the luminescence decay curves.This work demonstrates a way to tune phosphor luminescence properties by combining band gap engineering and energy transfer tailoring and provides an inspiring discussion on the different results of Ce~(3+)doping on the Ce~(3+)and Pr~(3+)emissions.     

TiNi合金制备技术及连续铸造的可行性探讨

TiNi合金具有优良的机械性能、耐腐蚀性能、超弹性以及形状记忆性能,被广泛应用于电子、机械、宇航、运输、建筑、化学、医疗、能源以及日常生活用品等各个领域,但其高昂的价格成为制约TiNi合金进一步发展的瓶颈。本文简单介绍了TiNi合金的性能和应用,综述了其传统制备技术及新的制备工艺,在讨论连续铸造特点的基础上对该技术用于制备TiNi合金的可行性进行了探讨。     

Use of sensitized luminescence of lanthanides in analysis of drugs

The sensitization of the Tb(III) and Eu(III) ions luminescence by drugs, the pyrocatechol, naphthyridine and heterocyclic aromatic acid derivatives, were studied. It was shown that a result of intramolecular energy transfer from the ligand molecule to the lanthanide ion increases the luminescence intensity of the latter by 10(8)-10(10) times. The luminescence properties of the complexes in solutions were investigated. The highly sensitive methods for luminescence determination of dopegyt, levodopum, dophaminum, nevigramon, furosemidum and cinchophenum were developed. The detection limits of the drugs are 0.0005, 0.02, 0.5, 0.01, 0.05 and 0.1, respectively.     

The dentin substrate: structure and properties related to bonding

OBJECTIVES: Dentin is a vital, hydrated composite material with structural components and properties that vary with location. These variations are reviewed along with alterations by physiological and pathological changes that allow classification into various forms of dentin. Structural characteristics and mechanical properties are reviewed and the limitations of our understanding of structure-property relationships for normal and modified forms of dentin are discussed with respect to their impact on dentin bonding. Recent progress in methods available to study dentin and its demineralization are emphasized with their promise to increase our understanding of dentin properties and structure. DATA SOURCES: Recent microstructural studies, focusing on scanning electron microscopy, atomic force microscopy and X-ray tomographic microscopy are included. A review of fundamental studies with emphasis on microstructurally sensitive methods, and prior reviews of basic mechanical properties are included with discussion of their correlation to composition and structure. STUDY SELECTION AND CONCLUSIONS: Emphasis in this work was placed on the major structural components of the tissue, including the collagen based organic matrix and its mineral reinforcement, the distribution of these components and their microstructural organization as related to mechanical properties and response to demineralization. Little information is included on biochemical and developmental studies or on non-collagenous proteins and other organic components for which limited understanding is available with respect to their role in structure-property relations and influence on bonding. In spite of the fact that the complexity of dentin precluded a comprehensive review, it is clear that local structural variations influence properties and impact nearly all preventive and restorative dental treatments. Much more work is needed in order to understand differences between vital and non-vital dentin, and dentin from extracted teeth. Although our knowledge is rudimentary in certain areas, increasingly sophisticated methods of studying dentin should provide the necessary information to model structure-property relations, optimize dentin bonding, and improve many aspects of preventive and restorative dentistry.     

磁性液体的制备及应用

本文介绍了金属氧化物、金属、氧化铁磁性液体的制备方法和磁性液体应用的工作原理 ,以及磁性液体在密封、轴承、研磨、阻尼、潜艇推进器、分离技术(选矿 )、生物医学等方面的应用。     

稀土有机框架材料（Ln-MOFs）的合成及应用

稀土有机框架材料 (Ln-MOFs) 因镧系离子存在特殊的电子排布[Xe]4fn (n = 0～14)而具有独特的发光性和磁性,且具有不饱和配位的金属位和大的比表面积,在化学工业中具有广阔的应用前景而备受关注. 研究表明,Ln-MOFs具有特殊的拓扑结构以及特定尺寸和形状的孔道,是一种新型多功能结晶材料,涉及了无机化学、有机化学以及配位化学等多学科,然而,通过简单的设计直接合成得到精确的Ln-MOFs是比较困难的,且有机配体和镧系金属单元具有无穷组合,故Ln-MOFs的合成与应用依然是今后研究的重点. 文中以设计合成稀土有机框架材料(Ln-MOFs)的配体类型为主线,综述了Ln-MOFs的合成与结构,重点阐述了其在催化剂、热稳定性、气体吸附、发光材料、磁性材料等方面的应用.      

Sub-10 nm lanthanide-doped SrFCl nanoprobes:Controlled synthesis,optical properties and bioimaging

Alkaline-earth dihalide nanocrystals(NCs) such as SrFCl, owing to their high chemical stability and low phonon energy, are excellent host materials for lanthanide(Ln~(3+)) doping to achieve desirable optical properties for various bioapplications, Herein, we report a novel strategy for the synthesis of sub-10 nm Ln~(3+)-doped SrFCl NCs with efficient upconverting and downshifting luminescence through a facile onestep hot-injection method. Utilizing the temperature-dependent upconverting luminescence(UCL) from the thermally coupled ~2H_(11/2) and ~4S_(3/2) levels of Er~(3+), we showed the potential of SrFCl:Yb,Er NCs as sensitive UCL nanoprobes for non-contact thermal sensing with a maximum detection sensitivity of 0.0066 K~(-1), which is among the highest values for thermal sensing based on Er~(3+)-activated UCL nanoprobes. Furthermore, by employing the intense downshifting luminescence from Tb~(3+) and Eu~(3+), we demonstrated the successful use of biotinylated SrFCl:Ce,Tb and SrFCl:Eu~(3+) nanoprobes for biotin receptor-targeted cancer cell imaging, thus revealing the great promise of SrFCl:Ln~(3+) nanoprobes for versatile bioapplications.     

Significance of multidrug resistance in the therapy of malignant tumors

Some human malignant tumours respond poorly to initial chemotherapy, indicating that they possess intrinsic resistance. On the other hand, in a significant portion of tumours after early promising results of therapy, the patients relapse, metastases appear, and acquired resistance to chemotherapy develops. The broad spectrum-resistance against chemotherapy is called multidrug resistance (MDR), and due to its clinical significance, studying of proteins responsible for multidrug resistance has become one of the most active research areas in biomedicine. There are several molecular mechanisms responsible for multidrug resistance. A group of filogenetically conservative plasmamembrane proteins actively extrudes different toxic compounds, xenobiotics, and also cytotoxic drugs from drug-resistant cells by using the energy of ATP. The clinically and biochemically most thoroughly characterized member of these proteins is the P-glycoprotein, which pumps hydrophobic drugs of natural origin and different chemical structure out of the cells. The recently cloned multidrug resistance associated protein (MRP) has also a broad substrate specificity, thus resembling P-glycoprotein. However, besides hydrophobic compounds, organic anions, glucuronide and glutathione conjugates are also excellent substrates of the MRP. The basic and clinically relevant properties of proteins causing multidrug resistance and the state of the art of current diagnostic approaches are summarized in this literature review. The different malignancies are characterized from the point of view of their multidrug resistance and recent clinical and biochemical data concerning therapeutic approaches for reversal of multidrug resistance are also presented.     

Medical resources and the internet. Making the connection

The Internet has provided a new forum through which medical information can be obtained and discussed. We review methods available to take advantage of this resource and provide a glimpse of electronically available information and discussions. These methods are useful for beginning and experienced users of the Internet.     

Blue-Light Emission from Undoped and Rare Earth-Doped Wide Bandgap Oxides

Blue-light emitting materials have been receivingconsiderable attention due to their applications for avariety of optoelectronic devices and display technolo-gies . Rare earth-doped compounds have long founduses as blue phosphors in a variety of devices due totheir intensely luminescent f-d and f-f electronictransitions[1]. Metal sulfides ,such as ZnS have beenutilized as conventional phosphors due to their excel-lent brightness . However ,the life span of the displaydevices is li mited due t…     

GIS-Based Engineering Management Service Functions: Taking GIS beyond Mapping for Municipal Governments

A geographic information system (GIS) is found to be a platform of choice for meeting the needs of several core engineering functions. However, there is a dearth of GIS usage for engineering management service functions (EMSFs), which typically are specific to individual jurisdictions. This study outlines a simple approach for automating EMSFs on a GIS platform and demonstrates its efficacy. In the first phase of this research, a review of GIS applications in various municipal government functions is conducted. The review indicated that most municipal governments have currently employed GIS for a variety of general administrative services such as revenue collection, data archival, and information dissemination purposes. The proposed approach is demonstrated by developing a GIS model for a sanitary sewer reimbursement (GIS-MSSR) program at a fast-growing urban municipality. Data modeling issues related to representing complex management tasks within the context of a relational database model are discussed. Development of functional requirement specifications for GIS models and their implementation are also discussed. The effectiveness of the approach is verified by highlighting productivity gains resulting from the development of GIS-MSSR. The research concluded that several complex engineering service management functions can be automated on GIS platforms to realize substantial productivity gains. Automating multiple tasks, however small they might be, in an integrated environment can increase the productivity even further.