Accurate assessment of biodiversity is important for scientists, conservationists and policy makers. With the development of DNA barcoding and metabarcoding, many cryptic species have been identified ...based on the sequence diversity of a ‘barcode’ region in the mitochondrial genome. These molecular identifications have increased the estimated number of species on Earth ten‐fold. Mitochondrial DNA heteroplasmy, in which multiple mitochondrial haplotypes coexist in a single organism, can interfere with the accuracy of these estimates. However, this phenomenon is still infrequently documented. The main reason is that it is difficult to distinguish heteroplasmic sequences from nuclear mitochondrial segments (Numts). We investigated the prevalence of multiple haplotypes in DNA barcoding sequences in fig wasps (Insect: Hymenoptera) by performing high‐throughput sequencing on individual specimens. DNA metabarcoding was artificially simulated by combining all the haplotype sequences. Using conventional DNA barcoding by Sanger sequencing, the 28 morphological species we studied were divided into 38 taxa, suggesting the existence of ten cryptic species. However, the haplotypes originating from a single specimen clustered into different cryptic species clades, which conflicted with the conventional barcoding results. Furthermore, when we artificially simulated DNA metabarcoding by mixing all haplotype sequences, the number of molecular operational taxonomic units (or putative species) was 3.2× the number of morphological species. These results indicate that the prevalence of multiple haplotypes within individual specimens may have an important impact on DNA barcode‐based species identification and biodiversity assessment more broadly.
We obtained multiple haplotypes within individual specimens by high‐throughput sequencing.
Multiple haplotypes originating from a single specimen could mislead DNA barcoding result.
Multiple haplotypes within individual specimens could result in overestimation of biodiversity in DNA metabarcoding.
Two G-quadruplex ligands: Co(H-La)2Cl2 (Co1) and Co(Lb)2CoCl4⋅2H2O (Co2) have been synthesized and characterized. Two cobalt oxoisoaporphine complexes exhibited selective cytotoxicity to SK-OV-3/DDP ...cells than for HL-7702 cells. Cytotoxic mechanism studies indicated that both Co1 and Co2 were telomerase inhibitor targeting c-myc, telomere, and bcl-2 G4s, and triggering cell senescence and apoptosis, which caused S phase arrest. They also induced mitochondrial dysfunction. The better antitumor activity of Co2, which should be correlated with a moiety of 2-5-(2-pyridinyl)-1H-pyrrol-2-ylpyridine in the Lb. Importantly, Co2 at high doses showed at least the same level of tumor growth inhibition efficacy compared to that of cisplatin, and better in vivo safety profile.
Co1 and Co2 exhibited selective cytotoxicity to SK-OV-3/DDP. They were telomerase inhibitor targeting c-myc, telomere, bcl-2 G4s, and triggering cell senescence and apoptosis. Co2 displayed high in vivo antitumor activity. Display omitted
•Two new Co1 and Co2 with oxoisoaporphine were synthesized.•Co1 and Co2 exhibited selective cytotoxicity toward SK-OV-3/DDP versus HL-7702.•Co1 and Co2 inhibited telomerase activity by binding c-myc, telomere, and bcl-2 G4s.•Co2 exhibited higher in vivo safety and close anticancer activity than cisplatin.
A quaternary ammonium salt covalently bound to chitosan (a functionalized biopolymer) is reported as an efficient and recyclable single-component catalyst for the synthesis of propylene carbonate ...from propylene oxide and CO
2 without any organic solvent or co-catalyst. Notably, this environmental benign and cost-effective process has great potential to be applied in various continuous flow reactors in industry.
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A quaternary ammonium salt covalently bound to chitosan is reported as an efficient and recyclable single-component catalyst for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and carbon dioxide without any organic solvent or co-catalyst. The catalyst can be easily recovered by filtration and reused for at least five times without obvious loss of its catalytic activity. The effects of the catalyst structure and various reaction parameters on the catalytic performance were in detail investigated. Moreover, the catalyst was found to be applicable to a variety of terminal epoxides, producing the corresponding cyclic carbonates in high yield and selectivity. Notably, this environmentally benign and cost-effective process has great potential to be applied in various continuous flow reactors in industry.
Two compounds previously isolated from traditional Chinese medicine,
(DC), 6-hydroxyl-oxoisoaporphine (H-L
), and 4,6-di(2-pyridinyl)benzo
isoindolo4,5,6-
quinolin-8(5
)-one (H-L
), were known to ...have in vitro antitumor activity and to selectively bind human telomeric, c-myc, and bcl-2 G-quadruplexes (G4s). In this study, the binding properties of these two compounds to telomerase were investigated through molecular docking and telomeric repeat amplication protocol and silver staining assay (TRAP-silver staining assay). The binding energies bound to human telomerase RNA were calculated by molecular docking to be -6.43 and -9.76 kcal/mol for H-L
and H-L
, respectively. Compared with H-L
, the ligand H-L
more strongly inhibited telomerase activity in the SK-OV-3 cells model.
The hemorrhagic and the ischemic types of stroke have similar symptoms in the early stage, but their treatments are completely different. The timely and effective discrimination of the two types of ...stroke can considerable improve the patients' prognosis. In this paper, a 16-channel and noncontact microwave-based stroke detection system was proposed and demonstrated for the potential differentiation of the hemorrhagic and the ischemic stroke. In animal experiments, 10 rabbits were divided into two groups. One group consisted of five cerebral hemorrhage models, and the other group consisted of five cerebral ischemia models. The two groups were monitored by the system to obtain the Euclidean distance transform value of microwave scattering parameters caused by pathological changes in the brain. The support vector machine was used to identify the type and the severity of the stroke. Based on the experiment, a discrimination accuracy of 96% between hemorrhage and ischemia stroke was achieved. Furthermore, the potential of monitoring the progress of intracerebral hemorrhage or ischemia was evaluated. The discrimination of different degrees of intracerebral hemorrhage achieved 86.7% accuracy, and the discrimination of different severities of ischemia achieved 94% accuracy. Compared with that with multiple channels, the discrimination accuracy of the stroke severity with a single channel was only 50% for the intracerebral hemorrhage and ischemia stroke. The study showed that the microwave-based stroke detection system can effectively distinguish between the cerebral hemorrhage and the cerebral ischemia models. This system is very promising for the prehospital identification of the stroke type due to its low cost, noninvasiveness, and ease of operation.
Designing efficient catalysts with a high selectivity toward hydrocarbons at a relatively low overpotential is of great significance for the application of the CO 2 electrochemical reduction reaction ...(CO 2 RR). In consideration of the advantages of Au or Ag pure metal with high faradaic efficiencies towards CO and a weaker competing hydrogen evolution reaction (HER) compared to Cu, this work employed density functional theory (DFT) calculations to explore whether the modification of Au or Ag pure metal could generate hydrocarbons rather than CO, as well as retain the two advantages above. Herein, 28 kinds of bimetallic alloys were investigated with models denoted as A/S(111) and A/S/A(111), where A is Au or Ag and S is a transition metal (Au, Ag, Pt, Pd, Ir, Rh, or Ni). Both the thermodynamic and kinetic aspects of the key elementary steps towards hydrocarbons are evaluated to reveal the catalytic performance of these alloys. The results indicated that Au/Pt/Au(111), Au/Rh/Au(111) and Au/Ni/Au(111) are the most promising catalyst candidates, being able to produce hydrocarbons with high faradaic efficiency at a much lower potential.
Designing efficient catalysts with a high selectivity toward hydrocarbons at a relatively low overpotential is of great significance for the application of the CO
2
electrochemical reduction reaction ...(CO
2
RR). In consideration of the advantages of Au or Ag pure metal with high faradaic efficiencies towards CO and a weaker competing hydrogen evolution reaction (HER) compared to Cu, this work employed density functional theory (DFT) calculations to explore whether the modification of Au or Ag pure metal could generate hydrocarbons rather than CO, as well as retain the two advantages above. Herein, 28 kinds of bimetallic alloys were investigated with models denoted as A/S(111) and A/S/A(111), where A is Au or Ag and S is a transition metal (Au, Ag, Pt, Pd, Ir, Rh, or Ni). Both the thermodynamic and kinetic aspects of the key elementary steps towards hydrocarbons are evaluated to reveal the catalytic performance of these alloys. The results indicated that Au/Pt/Au(111), Au/Rh/Au(111) and Au/Ni/Au(111) are the most promising catalyst candidates, being able to produce hydrocarbons with high faradaic efficiency at a much lower potential.
Designing efficient catalysts with a high selectivity toward hydrocarbons at a relatively low overpotential is of great significance for the application of the CO
2
electrochemical reduction reaction (CO
2
RR).
Stress invariant-based failure criteria, which are acknowledged for their simple expression but elegant description, still remain irrational considerations in its original formulation with regard to ...matrix failure in FRP composite materials. This study firstly re-examines the debatable hypothesis of infinite strength under equi-biaxial transverse compression. Afterwards, further attention is paid to the intrinsic relationship of transverse strengths when employing the assumption of transverse isotropy. During the formulation of the improved failure criteria from invariant theory, one notable feature is that deductions of strength coefficients, rather than direct use of measured strengths, are preferred to satisfy the mathematical and physical logic underlying the predefined assumptions and conditions. The analytical expressions for transverse shear strength and biaxial tensile strengths are deduced with Mohr’s fracture hypothesis, while biaxial compressive strength is estimated according to the theory of ductile/brittle transition. The predictions are validated based on computational micromechanics. The proposed criteria can be totally defined in terms of conventionally uniaxial strengths, thereby eliminating the need of biaxial strength parameters that are difficult to be measured experimentally. Combined practically and virtually experimental evaluations show that more reasonable and more accurate predictions under various stress conditions can be achieved by the developed stress invariant-based criteria, especially for the combined transverse normal stress case.
•An alternative analytical approach is proposed to determine biaxial strengths, resulting in a complete description of matrix failure envelopes with conventional uniaxial strengths.•The rationality of the proposed theory is evaluated and supported by biaxial damage scenarios within the computational micro-mechanics framework.•The present matrix failure criteria may give a better correlation compared with the existing invariant-based criteria, especially in combined transverse normal stresses.
S,N-co-doped porous carbon (SNPC) materials are good candidates for the cathodic oxygen-reduction reaction (ORR) and lithium-ion batteries (LIBs). However, SNPC gives low yield and is expensive. ...Herein, we report a new and efficient method for synthesizing a S,N-co-doped mesoporous carbon material through the carbonization of S,N-containing precursors in molten ZnCl sub(2), where ZnCl sub(2) served as the ionic solvent and Lewis acid catalyst. The resultant SNPC-800 showed a mesoporous structure with a specific surface area of 1235 m super(2) g super(-1) and a mesopore-size range of 10-45 nm, which were considerably larger than those obtained through the carbonization of ionic liquids and fabrication of graphene oxides. Furthermore, ORR measurements indicated good catalytic activity, comparable to the commercial Pt/C catalyst. Also the SNPC-800 material exhibited excellent catalytic stability, and high methanol tolerance compared to the commercial Pt/C catalyst. Density functional theory calculation results revealed that the catalytic properties originated from the synergistic effect of the S/N dopant and that the main catalytic reaction path followed an associative mechanism. LIB tests further showed high reversible capacity, as well as excellent cycling stability and rate performance.
Nanoholes on the basal plane of graphene can provide abundant mass transport channels and chemically active sites for enhancing the electrochemical performance. However, current thermal chemical ...etching processes to manufacture these nanoholes commonly suffer from insufficient process efficiency, scalability and controllability, due to the conventional bulk heating strategy lacks capability to promote the etching reactions. To address this issue, a novel process is developed using microwave irradiation to promote and control the chemical etching of graphene. In this process, the microwave can induce a selective heating of graphene in the liquid solution and then facilitate the etching reactions occurring on the graphene-etchant interface. Applying this strategy, a remarkable reduction of processing time from hour-scale to minute-scale compared to the conventional approaches have been achieved with the control of the population and area percentage of nanoholes on the graphene basal plane. Density functional theory and molecular dynamics simulations revealed that the formation of nanoholes originated from the cyclic etchant oxidation process occurring at the edge-sites atoms around pretreated vacancies on graphene basal plane. The obtained holey graphene oxide sheets exhibit excellent capacitive performance and electrochemical catalytic activity due to the improvements in the accessible surface area, ion diffusion, and heterogeneous charge transfer.
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