The desire for practical utilization of rechargeable lithium batteries with high energy density has motivated attempts to develop new electrode materials and battery systems. Here, without additional binders we present a simple vacuum filtration method to synthesize nitrogen and sulfur codoped graphene(N,S-G) blocking layer, which is ultra-lightweight, conductive, and free standing. When the N,S-G membrane was inserted between the catholyte and separator, the lithium–selenium(Li–Se)batteries exhibited a high reversible discharge capacity of 330.7 mAh g^(-1) at 1 C(1 C = 675 mA g^(-1)) after 500 cycles and high rate performance(over 310 mAh g^(-1) at 4 C) even at an active material loading as high as ～5 mg cm^(-2). This excellent performance can be ascribed to homogenous dispersion of the liquid active material in the electrode, good Li^+-ion conductivity, fast electronic transport in the conductive graphene framework, andstrong chemical confinement of polyselenides by nitrogen and sulfur atoms. More importantly, it is a promising strategy for enhancing the energy density of Li–Se batteries by using the catholyte with a lightweight heteroatom doping carbon matrix.
Diagnosis facilitates the discovery of an impending disease. A complete and accurate treatment of cancer depends heavily on its early medical diagnosis. Cancer, one of the most fatal diseases world-wide, consistently affects a larger number of patients each year. Magnetism, a physical property arising from the motion of electrical charges, which causes attraction and repulsion between objects and does not involve radiation, has been under intense investigation for several years. Magnetic materials show great promise in the application of image contrast enhancement to accurately image and diagnose cancer. Chelating gadolinium （Gd Ⅲ） and magnetic nanoparticles （MNPs） have the prospect to pave the way for diagnosis, operative management, and adjuvant therapy of different kinds of cancers. The potential of MNP-based magnetic resonance （MR） contrast agents （CAs） now makes it possible to image portions of a tumor in parts of the body that would be unclear with the conventional magnetic resonance imaging （MRI）. Multiple functionalities like variety of targeting ligands and image contrast enhancement have recently been added to the MNPs. Keeping aside the additional complexities in synthetic steps, costs, more convoluted behavior, and effects in-vivo, multifunctional MNPs still face great regulatory hurdles before clinical availability for cancer patients. The trade-off between additional functionality and complexity is a subject of ongoing debate. The recent progress regarding the types, design, synthesis, morphology, characterization, modification, and the in-vivo and in-vitro uses of different MRI contrast agents, including MNPs, to diagnose cancer will be the focus of this review. As our knowledge of MNPs＇ characteristics and applications expands, their role in the future management of cancer patients will become very important. Current hurdles are also discussed, along with future prospects of MNPs as the savior of cancer victims.
Nanoparticles（NPs） with easily modified surfaces have been playing an important role in biomedicine.As cancer is one of the major causes of death,tremendous efforts have been devoted to advance the methods of cancer diagnosis and therapy.Recently,magnetic nanoparticles（MNPs） that are responsive to a magnetic field have shown great promise in cancer therapy.Compared with traditional cancer therapy,magnetic field triggered therapeutic approaches can treat cancer in an unconventional but more effective and safer way.In this review,we will discuss the recent progress in cancer therapies based on MNPs,mainly including magnetic hyperthermia,magnetic specific targeting,magnetically controlled drug delivery,magnetofection,and magnetic switches for controlling cell fate.Some recently developed strategies such as magnetic resonance imaging（MRI） monitoring cancer therapy and magnetic tissue engineering are also addressed.
Electrochemical capacitors(EC) bear faster charge-discharge; however, their real applications are still on a long away due to lower capacitance and energy densities which mainly arise from simple surface charge accumulation or/and reaction. Here, a novel synthesis strategy was designed to obtain the purposeful hybrids of nickel cobalt double hydroxide(Ni Co DH) with genetic morphology to improve their electrochemical performance as electrode of EC. Nanostructures of metal hydroxides were grown on the nitrogen-doped graphene(NG) sheets by utilizing defects as nucleation sites and their composition was optimized both by tuning the ratio of Ni:Co as well as the counter halogen and carbonate anions to improve the porosity, stabilize the structure and mediate the redox reaction. The growth of the hybrids was guided by the Co ions through topochemical transformation supported by hoping charge transfer process and olation growth. NG overcoating successfully protects the nanostructure of Ni Co DH during electrochemical test and enhances overall conductivity of the electrode, improving the mass and ionic transportations. As a result, the hybrid exhibits excellent capacitance of 2925 F g-1 at 1 A g-1, as well as long cyclic stability of 10,000 cycles with good capacity retention of 90% at 16 A g-1. Furthermore, the hybrid shows excellent energy and power densities of 52 Wh kg-1 and 3191 W kg-1, respectively at discharge rate of 16 A g-1. It is expected that this strategy can be readily extended to other metal hydroxides, oxides and sulphides to improve their electrochemical performances.
