Plasmonics has developed for decades in the field of condensed matter physics and optics. Based on the classical Maxwell theory, collective excitations exhibit profound light‐matter interaction properties beyond classical physics in lots of material systems. With the development of nanofabrication and characterization technology, ultra‐thin two‐dimensional (2D) nanomaterials attract tremendous interest and show exceptional plasmonic properties. Here, we elaborate the advanced optical properties of 2D materials especially graphene and monolayer molybdenum disulfide (MoS2), review the plasmonic properties of graphene, and discuss the coupling effect in hybrid 2D nanomaterials. Then, the plasmonic tuning methods of 2D nanomaterials are presented from theoretical models to experimental investigations. Furthermore, we reveal the potential applications in photocatalysis, photovoltaics and photodetections, based on the development of 2D nanomaterials, we make a prospect for the future theoretical physics and practical applications.

(circular birefringence) and absorption losses (circular dichroism) with the circu larly polarized light (CPL) illumination. [10] CB arises from the difference in the real part of refractive index, leading to a dif ferent velocity for LCP and RCP compo nents, and thus results in the polarization rotation of the linearly polarized incident light. CD corresponds to the difference in the imaginary part of refractive index, resulting in a distinct absorption loss for LCP and RCP excitations. Besides the con ventional CD and CB, asymmetric trans mission (circular conversion dichroism) is another fundamental chiroptical pheno menon, which exists in the nondiffracting array, referring to different LCPtoRCP and RCPtoLCP conversion efficiencies. [11] All of these chiroptical phenomena have been successfully applied in the spectros copy for identifying special arrangements of chiral matters in biology, chemistry and physics as efficient diagnostic tools. [12][13][14][15][16] However, the chirop tical response in natural chiral materials is relatively weak due to the small electromagnetic (EM) interaction volume, [17] hence limits its further applications.Recent progress in plasmonics paves the way for the enhancement of chiroptical response. [18][19][20] Surface plasmons (SPs), as the collective electrons oscillation at the dielectric and metal interface, [21][22][23] present the capacity of light confine ment and field enhancement, which significantly improve the strength of lightmatter interactions. [24][25][26][27][28] With the uptodate nanofabrication technology, the study field of chirality has been extended from traditional chiral molecules to 3D metallic nanostructures. [29][30][31][32] Chiroptical responses of metallic meta molecules have been widely investigated, [33][34][35] and applied in various fields, such as biosensing, [36] chiral catalysis, [37] polari zation tuning, [38] and chiral photo detection.[39] The 3D metallic structure exhibited giant optical activity response because of the strong interaction between electric and magnetic resonant modes. [40,41] Different from 3D chiral ensembles, planar chiral structures show none chiral effect, as they can always coincide with their mirror images. However, 2D chirality was successfully found in the quasitwodimensional (quasi2D) chiral structure. [42] Moreover, recent reports show that even achiral nanomaterials have the ability to generate strong CD under an oblique CPL illumination. [43] This kind of extrinsic chirality arises from sym metry breaking of the incident light and the quasi2D material, which is quite different from the intrinsic chirality of 3D chiral The plasmonic chiroptical effect has been used to manipulate chiral states of light, where the strong field enhancement and light localization in metallic nanostructures can amplify the chiroptical response. Moreover, in metamaterials, the chiroptical effect leads to circular dichroism (CD), circular birefringence (CB), and asymmetric transmission. Potential applications enabled by chiral plasmonics...

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T he use of DNA to link nanoparticles (NPs) into complex self-assembled structures is an increasingly popular approach to the bottom-up design of nanoclusters and materials. 1À5 The selectivity and reversibility of DNA base-pair recognition, coupled with the relative stiffness of double-stranded DNA (dsDNA) 6À8 and a tunable assembly kinetics, 9 make DNA an ideal choice to create programmable interactions between NPs. This is accomplished by tethering multiple strands of DNA to a core NP (gold, silver, or CdSe core). 10À12 The outermost part of tethered strands is singlestranded DNA (ssDNA) with a specific sequence that will either link directly to another NP or connect to another NP via an additional linking strand. 13,14 The hybridization of ssDNA in linking regions directs the self-assembly of nanoparticles into largerscale structures. Their organization is controlled by the DNA sequences and linker architecture, 15À19 as well as by the NP geometry. 20 Using this approach, the precise fabrication of small nanoclusters and the formation of two-and three-dimensional superlattices has been achieved. 20À27While the approach of single-step, direct assembly is promising, many biological materials ; such as bone, hair, skin, and spider silk 28 ; take advantage of a more complex hierarchical scheme. In such a scenario, assembly at each scale results in units or structures that enable assembly at a larger scale. These processes have been evolved over aeons, so the development of synthetic multiscale self-assembly will prove challenging. In the context of DNA-tethered NPs, the most basic unit in such a hierarchical approach is a dimer of two NPs. As a first step toward a synthetic multiscale assembly, here we examine in detail the structure of dimer units. The structure of these dimers is complicated by the fact that the surface curvature of the NP is on a scale comparable to the length of the connecting DNA. In such a regime, the behavior of polymer chains (such as DNA) attached to the surface is known to deviate significantly from the free-chain behavior. 29,30 In this paper, we examine the structure of DNA-linked NP dimers by a combination of in situ dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS), complemented by molecular simulations and theory. The DLS method probes a hydrodynamic measure of an angular-averaged dimer size. The in situ SAXS experiments reveal more detailed information on the interparticle distances within the dimer. The numerical modeling provides a detailed molecular picture that helps to interpret the experimental findings and develop a theoretical description.When the NPs are linked by dsDNA with a separation less than the persistence length, the interparticle distance is a linear function of the DNA length, due to the rigidity of dsDNA. For longer ssDNA linkers, the * Address correspondence to ogang@bnl.gov, fstarr@wesleyan.edu.Received for review April 6, 2012 and accepted July 13, 2012. Published online 10.1021/nn301528hABSTRACT We construct nanoparticle dimers lin...

Background and Objectives: To achieve the goal of 300,000 general practitioners by 2020—an increase of 215,200 in a decade—China is utilizing multiple training pathways. To comprehensively illustrate general practitioner training strategies in China, this article introduces and describes these pathways. Methods: We used descriptive policy analysis. This involved taking an inventory of existing literature and source documents and developing a model to illustrate pathways for training general practice physicians. Results: The rural doctor pathway represents rural clinicians who had only basic training and practiced multiple years prior to training reforms. The 3+2 pathway to assistant general practitioners requires 3 years of junior college and 2 years of clinical training. The transfer pathway for current physicians requires 1-2 years of training. The 5+3 pathway comprises 5 years of bachelor of science degree training in clinical medicine and 3 years of standardized residency training. Despite the development of advanced degree programs, their use remains limited. Conclusions: These pathways illustrate significant heterogeneity in training of general practitioners. Training ranges from a 2-year technical degree to a doctorate with research. Emphasis on the 5+3 track shows promise for China’s goals of improved quality and new goal of 500,000 additional general practitioners by 2030.

The recently developed ability to controllably connect biological and inorganic objects on a molecular scale opens a new page in biomimetic methods with potential applications in biodetection, tissue engineering, targeted therapeutics and drug/gene delivery. Particularly in the biodetection arena, a rapid development of new platforms has largely been stimulated by a spectrum of novel nanomaterials with physical properties that offer efficient, sensitive and inexpensive molecular sensing. Recently, DNA-functionalized nano-objects have emerged as a new class of nanomaterials that can be controllably assembled in predesigned structures. Such DNA-based nanoscale structures might provide a new detection paradigm due to their regulated optical, electrical and magnetic responses, chemical heterogeneity and high local biomolecular concentration. The specific biorecognition DNA and its physical-chemical characteristics allows for an exploitation of DNA-functionalized nanomaterials for sensing of nucleic acids, while a broad tunability of DNA interactions permits extending their use for detection of proteins, small molecules and ions. We discuss the progress that was achieved in the last decade in the exploration of new detection methods based on DNA-incorporating nanomaterials as well as their applications to gene delivery. The comparison between various detection platforms, their sensitivity and selectivity, and specific applications are reviewed.

DNA linked nanoparticles are applied as a sensor for single-stranded DNA detection. The detection is based on nanocluster dimer disassembly triggered by the binding of target nucleic acid strands. Target detection and disassembly kinetics are followed in real-time using dynamic light scattering. The observed disassembly process is in agreement with a two-step kinetic model. The DNA sensing is found to be selective down to the level of a single base mismatch, even in the presence of a high concentration of interference DNA. The method further provides label-free detection of DNA in minutes and demonstrates the use of this new class of nanoclusters as a powerful platform for nucleic acid detection.

Asthma imposes a substantial burden on individuals and societies. Patients with asthma need high-quality primary care management; however, evidence suggests the quality of this care can be highly variable. Here we identify and report factors contributing to high-quality management. Twelve primary care global asthma experts, representing nine countries, identified key factors. A literature review (past 10 years) was performed to validate or refute the expert viewpoint. Key driving factors identified were: policy, clinical guidelines, rewards for performance, practice organisation and workforce. Further analysis established the relevant factor components. Review evidence supported the validity of each driver; however, impact on patient outcomes was uncertain. Single interventions (e.g. healthcare practitioner education) showed little effect; interventions driven by national policy (e.g. incentive schemes and teamworking) were more effective. The panel’s opinion, supported by literature review, concluded that multiple primary care interventions offer greater benefit than any single intervention in asthma management.