Guangzhou HKUST Fok Ying Tung Research Institute

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure-property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).

BACKGROUND: There is a rapidly increasing amount of de novo genome assembly using next-generation sequencing (NGS) short reads; however, several big challenges remain to be overcome in order for this to be efficient and accurate. SOAPdenovo has been successfully applied to assemble many published genomes, but it still needs improvement in continuity, accuracy and coverage, especially in repeat regions. FINDINGS: To overcome these challenges, we have developed its successor, SOAPdenovo2, which has the advantage of a new algorithm design that reduces memory consumption in graph construction, resolves more repeat regions in contig assembly, increases coverage and length in scaffold construction, improves gap closing, and optimizes for large genome. CONCLUSIONS: Benchmark using the Assemblathon1 and GAGE datasets showed that SOAPdenovo2 greatly surpasses its predecessor SOAPdenovo and is competitive to other assemblers on both assembly length and accuracy. We also provide an updated assembly version of the 2008 Asian (YH) genome using SOAPdenovo2. Here, the contig and scaffold N50 of the YH genome were ~20.9 kbp and ~22 Mbp, respectively, which is 3-fold and 50-fold longer than the first published version. The genome coverage increased from 81.16% to 93.91%, and memory consumption was ~2/3 lower during the point of largest memory consumption.

Hundreds of individual human cancer genome sequences are expected to be published in 2010, and thousands per year after that. The International Cancer Genome Consortium (ICGC) was launched with the aim of keeping track of the data relating to large-scale cancer genome studies of all major cancers in adults and children — a total of 50 different cancer types and/or subtypes. In this issue the ICGC team ( http://www.icgc.org ) spells out the policies and planning for the project. The International Cancer Genome Consortium (ICGC) was launched to coordinate large-scale cancer genome studies in tumours from 50 different cancer types and/or subtypes that are of clinical and societal importance across the globe. Systematic studies of more than 25,000 cancer genomes at the genomic, epigenomic and transcriptomic levels will reveal the repertoire of oncogenic mutations, uncover traces of the mutagenic influences, define clinically relevant subtypes for prognosis and therapeutic management, and enable the development of new cancer therapies.

Phosphorescence has rarely been observed in pure organic chromophore systems at room temperature. We herein report efficient phosphorescence from the crystals of benzophenone and its derivatives with a general formula of (X-C 6 H 4 ) 2 C═O (X = F, Cl, Br) as well as methyl 4-bromobenzoate and 4,4′-dibromobiphenyl under ambient conditions. These luminogens are all nonemissive when they are dissolved in good solvents, adsorbed on TLC plates, and doped into polymer films, because active intramolecular motions such as rotations and vibrations under these conditions effectively annihilate their triplet excitons via nonradiative relaxation channels. In the crystalline state, the intramolecular motions are restricted by the crystal lattices and intermolecular interactions, particularly C−H···O, N−H···O, C−H···X (X = F, Cl, Br), C−Br···Br−C, and C−H···π hydrogen bonding. The physical constraints and multiple intermolecular interactions collectively lock the conformations of the luminogen molecules. This structural rigidification effect makes the luminogens highly phosphorescent in the crystalline state at room temperature.

Efficient solid-state emitters developed by a new approach are described. While emission from triphenylamine (TPA) and its dimer (DTPA) is weakened by aggregation, attaching tetraphenylethene (TPE) units to the amines boosts their emission efficiencies up to 100% in the aggregate state without harming their hole-transport properties. The resultant 3TPETPA and 4TPEDTPA luminogens show excellent electroluminescence performance.

Displays based on inorganic light-emitting diodes (LED) are considered as the most promising one among the display technologies for the next-generation. The chip for LED display bears similar features to those currently in use for general lighting, but it size is shrunk to below 200 microns. Thus, the advantages of high efficiency and long life span of conventional LED chips are inherited by miniaturized ones. As the size gets smaller, the resolution enhances, but at the expense of elevating the complexity of fabrication. In this review, we introduce two sorts of inorganic LED displays, namely relatively large and small varieties. The mini-LEDs with chip sizes ranging from 100 to 200 μm have already been commercialized for backlight sources in consumer electronics applications. The realized local diming can greatly improve the contrast ratio at relatively low energy consumptions. The micro-LEDs with chip size less than 100 μm, still remain in the laboratory. The full-color solution, one of the key technologies along with its three main components, red, green, and blue chips, as well color conversion, and optical lens synthesis, are introduced in detail. Moreover, this review provides an account for contemporary technologies as well as a clear view of inorganic and miniaturized LED displays for the display community.

The thermochromic and mechanochromic fluorescence of diphenyldibenzofulvenes is investigated. Emission is boosted and blue-shifted upon crystallization. Yellow emissive crystals of the material transform to green fluorescent crystals upon heating before melting. Reversible switching of the emission color and efficiency are achieved by repeated amorphization and crystallization of dye molecules by a pure thermal process or grinding–heating cycles.

The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized here. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared. Research directions on the further development of active, stable, and low-cost electrocatalysts to meet the ultimate commercialization of PEMFCs and AMFCs are also discussed.

The development of new polymerization reactions is of critical importance to macromolecule science. In this critical review, we summarize the research efforts to incubate alkyne-azide click reactions into a versatile polymerization technique for the synthesis of poly(triazole)s (PTAs) with linear and hyperbranched structures. Cu(I)- and Ru(II)-catalyzed click polymerizations afforded 1,4- and 1,5-regioregular PTAs, respectively. Whereas traditional thermal cycloadditions normally generate regiorandom products, PTAs with 1,4-regioisomer contents up to 95% were created by utilizing the electronic effect involved in the thermal click polymerizations of aroylacetylenes with azides. The PTAs showed unique functional properties, such as luminescence, chromism, fluorescence imaging, emission superquenching, chain helicity, optical nonlinearity, light refractivity, photovoltaic effect, cytocompatibility and biodegradability (145 references).

Abstract Proton exchange membrane fuel cells convert hydrogen and oxygen into electricity without emissions. The high cost and low durability of Pt-based electrocatalysts for the oxygen reduction reaction hinder their wide application, and the development of non-precious metal electrocatalysts is limited by their low performance. Here we design a hybrid electrocatalyst that consists of atomically dispersed Pt and Fe single atoms and Pt–Fe alloy nanoparticles. Its Pt mass activity is 3.7 times higher than that of commercial Pt/C in a fuel cell. More importantly, the fuel cell with a low Pt loading in the cathode (0.015 mg Pt cm −2 ) shows an excellent durability, with a 97% activity retention after 100,000 cycles and no noticeable current drop at 0.6 V for over 200 hours. These results highlight the importance of the synergistic effects among active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-Pt electrocatalysts for electrochemical devices.

In this contribution, we conceptually present a new avenue to construction of molecular functional materials with high performance of circularly polarised luminescence (CPL) in the condensed phase. A molecule (1) containing luminogenic silole and chiral sugar moieties was synthesized and thoroughly characterized. In a solution of 1, no circular dichroism (CD) and fluorescence emission are observed, but upon molecular aggregation, both the CD and fluorescence are simultaneously turned on, showing aggregation-induced CD (AICD) and emission (AIE) effects. The AICD effect is supported by the fact that the molecules readily assemble into right-handed helical nanoribbons and superhelical ropes when aggregated. The AIE effect boosts the fluorescence quantum efficiency (ΦF) by 136 fold (ΦF, ∼0.6% in the solution versus ∼81.3% in the solid state), which surmounts the serious limitations of aggregation-caused quenching effect encountered by conventional luminescent materials. Time-resolved fluorescence study and theoretical calculation from first principles conclude that restriction of the low-frequency intramolecular motions is responsible for the AIE effect. The helical assemblies of 1 prefer to emit right-handed circularly polarised light and display large CPL dissymmetry factors (gem), whose absolute values are in the range of 0.08–0.32 and are two orders of magnitude higher than those of commonly reported organic materials. We demonstrate for the first time the use of a Teflon-based microfluidic technique for fabrication of the fluorescent pattern. This shows the highest gem of −0.32 possibly due to the enhanced assembling order in the confined microchannel environment. The CPL performance was preserved after more than half year storage under ambient conditions, revealing the excellent spectral stability. Computational simulation was performed to interpret how the molecules in the aggregates interact with each other at the molecular level. Our designed molecule represents the desired molecular functional material for generating efficient CPL in the solid state, and the current study shows the best results among the reported organic conjugated molecular systems in terms of emission efficiency, dissymmetry factor, and spectral stability.

Turning "stone" into "gold": pyrene, a faint fluorophore in the solid state, is transformed into a bright emitter by decorating it with tetraphenylethene units; the new luminogen is thermally and morphologically stable and its light-emitting diode shows excellent performance, with external quantum efficiency and current efficiency up to 4.95% and 12.3 cd A(-1), respectively.

Two is better than one: a luminogen comprised of two units of tetraphenylethene (BTPE) emits more efficiently than that with one tetraphenylethene unit in the solid state; self-assembly of the BTPE molecules affords crystalline microfibers that fluoresce in 100% efficiency, giving the largest effect of aggregation-induced emission (alpha(AIE)-->infinity); BTPE-based electroluminescence devices emit in current efficiency up to approximately 7.3 cd/A.

Fluorescence of a hyperbranched poly(silylenephenylene) is weakened with increasing quencher concentration in an exponential fashion, giving an extremely high quenching constant and making the polymer a highly sensitive chemosensor for explosive detection.

Chemical transformations of small molecules have served as a rich source of reactions for the development of new polymerization processes, and “click” reaction has the potential to become a powerful polymerization technique. We herein give a brief account of the research efforts devoted to the development of click reaction into a new polymerization process. Remarkable progresses have been made in recent years in the exploration of metal-mediated and metal-free click polymerization systems and in the syntheses of linear and hyperbranched polytriazoles with regioregular molecular structures and advanced functional properties. We also discuss the existing limitations and challenges as well as the promising opportunities and directions in fostering the click polymerization into a versatile tool for the construction of new macromolecules with well-defined structures and multifaceted functionalities.

Many emerging applications such as intruder detection and border protection drive the fast increasing development of device-free passive (DfP) localization techniques. In this paper, we present Pilot, a Channel State Information (CSI)-based DfP indoor localization system in WLAN. Pilot design is motivated by the observations that PHY layer CSI is capable of capturing the environment variance due to frequency diversity of wideband channel, such that the position where the entity located can be uniquely identified by monitoring the CSI feature pattern shift. Therefore, a ``passive'' radio map is constructed as prerequisite which include fingerprints for entity located in some crucial reference positions, as well as clear environment. Unlike device-based approaches that directly percepts the current state of entities, the first challenge for DfP localization is to detect their appearance in the area of interest. To this end, we design an essential anomaly detection block as the localization trigger relying on the CSI feature shift when entity emerges. Afterwards, a probabilistic algorithm is proposed to match the abnormal CSI to the fingerprint database to estimate the positions of potential existing entities. Finally, a data fusion block is developed to address the multiple entities localization challenge. We have implemented Pilot system with commercial IEEE 802.11n NICs and evaluated the performance in two typical indoor scenarios. It is shown that our Pilot system can greatly outperform the corresponding best RSS-based scheme in terms of anomaly detection and localization accuracy.

After the publication of ‘SOAPdenovo2: an empirically improved memory-efficient short-read de novo assembler. GigaScience 2012 1:18’ [1] this paper was used as case study by the ISA, Research Object and Nanopu-blication communities to use their data models to try to quantitatively assess the reproducibility of published research. While the supporting data and overall results were found to be accurate, a number of semantic problems were detected in a few points of interpretation, and in order to ensure the accuracy of the scientific we now outline these in this correction article. While there are huge improvements to the quality of the resulting assemblies, other than the tables it was not stressed in the text that the speed of SOAPdenovo2 can be slightly slower than SOAPdenovo v1. In the testing an assessment section (page 3), based on the correct results in table 1, where we say the scaffold N50 metric is an order of magnitude longer from SOAPdenovo2 versus SOAPdenovo1, this was actually 45 times longer. Also in the testing an assessment section, based on the correct results in table 1, where we say SOAPdenovo2 produced a contig N50 1.53 times longer than ALLPATHS-LG, this should be 2.18 times longer. Finally in this section, where we say the correct assembly length produced by SOAPdenovo2 was 3–80 fold longer than SOAPdenovo1, this should be 3–64 fold longer. To see more about how these errors were detected see the case study article [2]. To access all the supporting materials, ISA metadata and pipelines implemented in Galaxy to test these results on your own, please see the supporting entry in GigaDB [3].

Catalysts consisting of atomically dispersed Pt (Pt iso ) species on CeO 2 supports have received recent interest due to their potential for efficient metal utilization in catalytic convertors. However, discrepancies exist between the behavior (reducibility, interaction strength with adsorbates) of high surface area Pt iso /CeO 2 systems and of well-defined surface science and computational model systems, suggesting differences in Pt local coordination in the two classes of materials. Here, we reconcile these differences by demonstrating that high surface area Pt iso /CeO 2 synthesized at low Pt loadings (<0.1% weight) exhibit resistance to reduction and sintering up to 500 °C in 0.05 bar H 2 and minimal interactions with CO—properties previously seen only for model system studies. Alternatively, Pt loadings >0.1 weight % produce a distribution of sub-nanometer Pt structures, which are difficult to distinguish using common characterization techniques, and exhibit strong interactions with CO and weak resistance to sintering, even in 0.05 bar H 2 at 50 °C—properties previously seen for high surface area materials. This work demonstrates that low metal loadings can be used to selectively populate the most thermodynamically stable adsorption sites on high surface area supports with atomically dispersed metals. Further, the site uniformity afforded by this synthetic approach is critical for the development of relationships between atomic scale local coordination and functional properties. Comparisons to recent studies of Pt iso /TiO 2 suggest a general compromise between the stability of atomically dispersed metal catalysts and their ability to interact with and activate molecular species.

A unique 1D nanostructure of Pt@CeO 2 –BDC was prepared from Pt@CeBDC MOF. The Pt@CeO 2 –BDC was rich in oxygen vacancies (i.e., XPS O β /(O α + O β ) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO 2 . Toluene oxidation was conducted in a spectroscopic operando Raman–online FTIR reactor to elucidate the reaction mechanism and establish the structure–activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO 2 –BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO 2 and H 2 O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt 2+ with minor amounts of Pt 0 and Pt 4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO 2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir–Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO 2 and H 2 O mainly by the Mars-van Krevelen mechanism.

COVID-19 is an acute respiratory disease caused by SARS-CoV-2, which has high transmissibility. People infected with SARS-CoV-2 can develop symptoms including cough, fever, pneumonia and other complications, which in severe cases could lead to death. In addition, a proportion of people infected with SARS-CoV-2 may be asymptomatic. At present, the primary diagnostic method for COVID-19 is reverse transcription-polymerase chain reaction (RT-PCR), which tests patient samples including nasopharyngeal swabs, sputum and other lower respiratory tract secretions. Other detection methods, e.g., isothermal nucleic acid amplification, CRISPR, immunochromatography, enzyme-linked immunosorbent assay (ELISA) and electrochemical sensors are also in use. As the current testing methods are mostly performed at central hospitals and third-party testing centres, the testing systems used mostly employ large, high-throughput, automated equipment. Given the current situation of the epidemic, point-of-care testing (POCT) is advantageous in terms of its ease of use, greater approachability on the user's end, more timely detection, and comparable accuracy and sensitivity, which could reduce the testing load on central hospitals. POCT is thus conducive to daily epidemic control and achieving early detection and treatment. This paper summarises the latest research advances in POCT-based SARS-CoV-2 detection methods, compares three categories of commercially available products, i.e., nucleic acid tests, immunoassays and novel sensors, and proposes the expectations for the development of POCT-based SARS-CoV-2 detection including greater accessibility, higher sensitivity and lower costs.