Feng Tang

Bio: Feng Tang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Wavefront & Interferometry. The author has an hindex of 18, co-authored 106 publications receiving 1078 citations. Previous affiliations of Feng Tang include University of Cambridge & Renmin University of China.

Ag-Incorporated Organic–Inorganic Perovskite Films and Planar Heterojunction Solar Cells

Abstract: Controlled doping for adjustable material polarity and charge carrier concentration is the basis of semiconductor materials and devices, and it is much more difficult to achieve in ionic semiconductors (e.g., ZnO and GaN) than in covalent semiconductors (e.g., Si and Ge), due to the high intrinsic defect density in ionic semiconductors. The organic–inorganic perovskite material, which is frenetically being researched for applications in solar cells and beyond, is also an ionic semiconductor. Here we present the Ag-incorporated organic–inorganic perovskite films and planar heterojunction solar cells. Partial substitution of Pb2+ by Ag+ leads to improved film morphology, crystallinity, and carrier dynamics as well as shifted Fermi level and reduced electron concentration. Consequently, in planar heterojunction photovoltaic devices with inverted stacking structure, Ag incorporation results in an enhancement of the power conversion efficiency from 16.0% to 18.4% in MAPbI3 based devices and from 11.2% to 15.4%...

A novel Fe-N-C catalyst for efficient oxygen reduction reaction based on polydopamine nanotubes.

Abstract: One-dimensional Fe–N-codoped porous carbon materials have shown great potential as sustainable and efficient oxygen reduction reaction (ORR) catalysts. Herein, a highly active ORR 1D Fe–N–C catalyst has been developed by pyrolyzing a complex of polydopamine nanotubes and Fe(NO3)3 at 800 °C. Porous PDA nanotubes as a resource for nitrogen-doped carbon and a coordination platform for Fe3+ can provide well-distributed catalytic sites (Fe–N) after pyrolysis, and generate graphene-like carbon covers with proper thicknesses on Fe/Fe3C nanoparticles that effectively prevent agglomeration. Thanks to the 1D mesoporous morphology and hybrid composition, the rationally designed catalyst exhibits comparable ORR activity to the commercial Pt/C catalyst, and superior durability and methanol tolerance in alkaline media. Polydopamine nanotubes have demonstrated effects in the fabrication of efficient ORR catalysts which can be described as “killing three birds with one stone”. The excellent electrocatalytic performance makes this novel 1D Fe–N–C catalyst a promising non-precious metal catalyst for practical fuel cell application.

Modal wavefront reconstruction based on Zernike polynomials for lateral shearing interferometry: comparisons of existing algorithms.

Abstract: Four modal methods of reconstructing a wavefront from its difference fronts based on Zernike polynomials in lateral shearing interferometry are currently available, namely the Rimmer-Wyant method, elliptical orthogonal transformation, numerical orthogonal transformation, and difference Zernike polynomial fitting. The present study compared these four methods by theoretical analysis and numerical experiments. The results show that the difference Zernike polynomial fitting method is superior to the three other methods due to its high accuracy, easy implementation, easy extension to any high order, and applicability to the reconstruction of a wavefront on an aperture of arbitrary shape. Thus, this method is recommended for use in lateral shearing interferometry for wavefront reconstruction.

Chemoenzymatic synthesis of glycoengineered IgG antibodies and glycosite-specific antibody–drug conjugates

Abstract: Glycoengineered therapeutic antibodies and glycosite-specific antibody-drug conjugates (gsADCs) have generated great interest among researchers because of their therapeutic potential. Endoglycosidase-catalyzed in vitro glycoengineering technology is a powerful tool for IgG Fc (fragment cystallizable) N-glycosylation remodeling. In this protocol, native heterogeneously glycosylated IgG N-glycans are first deglycosylated with a wild-type endoglycosidase. Next, a homogeneous N-glycan substrate, presynthesized as described here, is attached to the remaining N-acetylglucosamine (GlcNAc) of IgG, using a mutant endoglycosidase (also called endoglycosynthase) that lacks hydrolytic activity but possesses transglycosylation activity for glycoengineering. Compared with in vivo glycoengineering technologies and the glycosyltransferase-enabled in vitro engineering method, the current approach is robust and features quantitative yield, homogeneous glycoforms of produced antibodies and ADCs, compatibility with diverse natural and non-natural glycan structures, convenient exploitation of native IgG as the starting material, and a well-defined conjugation site for antibody modifications. Potential applications of this method cover a broad scope of antibody-related research, including the development of novel glycoengineered therapeutic antibodies with enhanced efficacy, site-specific antibody-drug conjugation, and site-specific modification of antibodies for fluorescent labeling, PEGylation, protein cross-linking, immunoliposome formation, and so on, without loss of antigen-binding affinity. It takes 5-8 d to prepare the natural or modified N-glycan substrates, 3-4 d to engineer the IgG N-glycosylation, and 2-5 d to synthesize the small-molecule toxins and prepare the gsADCs.

Real-Time Analysis on Drug-Antibody Ratio of Antibody-Drug Conjugates for Synthesis, Process Optimization, and Quality Control.

Abstract: Drug-antibody ratio (DAR) of antibody-drug conjugates (ADCs) is important for their therapeutic efficacy and pharmacokinetics, therefore control on DAR in synthesis process is a key for ADC quality control. Although various analytical methods were reported, the real-time monitoring on DAR is still a challenge because time-consuming sample preparation is usually needed during the analysis. Antibody deglycosylation of ADC simplifies DAR measurement, however long-time PNGaseF digestion for deglycosylation hampers the real-time detection. Here, we report a rapid DAR analysis within 15 min by robust deglycosylation treatment and LC-MS detection that enables real-time DAR monitoring for optimization on ADC synthetic process. With this approach, we were able to screen suitable conjugation conditions efficiently and afford the ADCs with expected DARs. To the best of our knowledge, this is the first report on real-time DAR analysis of ADCs for conjugation optimization and quality control, compatible with random lysine-linked ADCs, glycosite-specific ADCs, and the complicated dual-payload ADCs.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Methods in Enzymology.

Abstract: I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

International Tables for X-Ray Crystallography

Abstract: International Tables for X-Ray Crystallography (Published for the International Union of Crystallography.) Vol. 1: Symmetry Groups. Edited by Norman F. M. Henry and Kathleen Lonsdale. Pp. xi + 558. (Birmingham: Kynoch Press, 1952.) 105s.

Perovskite-based photodetectors: materials and devices

Abstract: While the field of perovskite-based optoelectronics has mostly been dominated by photovoltaics, light-emitting diodes, and transistors, semiconducting properties peculiar to perovskites make them interesting candidates for innovative and disruptive applications in light signal detection. Perovskites combine effective light absorption in the broadband range with good photo-generation yield and high charge carrier mobility, a combination that provides promising potential for exploiting sensitive and fast photodetectors that are targeted for image sensing, optical communication, environmental monitoring or chemical/biological detection. Currently, organic–inorganic hybrid and all-inorganic halide perovskites with controlled morphologies of polycrystalline thin films, nano-particles/wires/sheets, and bulk single crystals have shown key figure-of-merit features in terms of their responsivity, detectivity, noise equivalent power, linear dynamic range, and response speed. The sensing region has been covered from ultraviolet-visible-near infrared (UV-Vis-NIR) to gamma photons based on two- or three-terminal device architectures. Diverse photoactive materials and devices with superior optoelectronic performances have stimulated attention from researchers in multidisciplinary areas. In this review, we provide a comprehensive overview of the recent progress of perovskite-based photodetectors focusing on versatile compositions, structures, and morphologies of constituent materials, and diverse device architectures toward the superior performance metrics. Combining the advantages of both organic semiconductors (facile solution processability) and inorganic semiconductors (high charge carrier mobility), perovskites are expected to replace commercial silicon for future photodetection applications.