Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs), which is the most toxic DNA damage in cells. Unrepaired DSBs can cause genome instability, ...tumorigenesis or cell death. DNA end synapsis is the first and probably the most important step of the NHEJ pathway, aiming to bring two broken DNA ends close together and provide structural stability for end processing and ligation. This process is mediated through a group of NHEJ proteins forming higher-order complexes, to recognise and bridge two DNA ends. Spatial and temporal understanding of the structural mechanism of DNA-end synapsis has been largely advanced through recent structural and single-molecule studies of NHEJ proteins. This review focuses on core NHEJ proteins that mediate DNA end synapsis through their unique structures and interaction properties, as well as how they play roles as anchor and linker proteins during the process of 'bridge over troubled ends'.
Utilizing pyridine catalysis, we developed a visible‐light‐induced transition‐metal‐free radical borylation reaction of unactivated alkyl bromides that features a broad substrate scope and mild ...reaction conditions. Mechanistic studies revealed a novel nucleophilic substitution/photoinduced radical formation pathway, which could be utilized to trigger a variety of radical processes.
To B or not to Br: A visible‐light‐induced organocatalytic borylation reaction of unactivated alkyl bromides was developed. This reaction exhibits a broad substrate scope, and mechanistic studies revealed a novel nucleophilic substitution/photoinduced radical formation pathway.
Using the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), the ionospheric Rayleigh‐Taylor instability growth rate is calculated. ...The seasonal and longitudinal variations of the growth rate from the TIEGCM appear to match that of the spread F observed by various satellite missions. The growth rate is strongly dependent on the angle between the sunset terminator and the geomagnetic field line near the magnetic equator. The TIEGCM simulations with nonmigrating tides show the zonal wave number 4 structure in the Rayleigh‐Taylor instability due to the inclusion of the nonmigrating diurnal eastward zonal wave number 3 and semidiurnal eastward zonal wave number 2 tides.
Key Points
Modeled R‐T growth rate resembles the bubble occurrence
Nonmigrating tide can effect the R‐T growth rate
There are other factors affecting the bubble growth rate
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•The mechanisms of microwave absorption were analyzed in detail.•The preparation methods of carbon/magnetic metal composites were summarized.•Composites with different components, ...morphologies and structures were reviewed.•Challenges and future prospects for carbon/magnetic metal composites were proposed.
At present, developing high-efficiency microwave absorption materials with properties including light-weight, thin thickness, strong absorbing intensity and broad bandwidth is an urgent demand to solve the electromagnetic pollution issues. An ideal microwave absorber should have excellent dielectric and magnetic loss capabilities, thereby inducing attenuation and absorption of incident electromagnetic radiation. Recently, various carbon/magnetic metal composites have been developed and expected to become promising candidates for high-performance microwave absorbers. In this review, we introduce the mechanisms of microwave absorption and summarize the recent advances in carbon/magnetic metal composites. Preparation methods and microwave absorption properties of carbon/magnetic metal composites with different components, morphologies and microstructures are discussed in detail. Finally, the challenges and future prospects of carbon/magnetic metal absorbing materials are also proposed, which will be useful to develop high-performance microwave absorption materials.
Heterostructured metal—organic framework (MOF)‐on‐MOF thin films have the potential to cascade the various properties of different MOF layers in a sequence to produce functions that cannot be ...achieved by single MOF layers. An integration method that relies on van der Waals interactions, and which overcomes the lattice‐matching limits of reported methods, has been developed. The method deposits molecular sieving Cu‐TCPP (TCPP=5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin) layers onto semiconductive Cu‐HHTP (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene) layers to obtain highly oriented MOF‐on‐MOF thin films. For the first time, the properties in different MOF layers were cascaded in sequence to synergistically produce an enhanced device function. Cu‐TCPP‐on‐Cu‐HHTP demonstrated excellent selectivity and the highest response to benzene of the reported recoverable chemiresistive sensing materials that are active at room temperature. This method allows integration of MOFs with cascading properties into advanced functional materials.
MOF‐on‐MOF thin films were prepared from Cu‐HHTP (HHTP=hexahydrotriphenylene) and Cu‐TCPP (TCPP=tetrakis(4‐carboxyphenyl)porphyrin frameworks). The properties of the MOF layers cascade to produce functionality not achieved by a single layer. The MOF‐on‐MOF films demonstrate excellent selectivity and the highest response to benzene among reported recoverable chemiresistive sensing materials active at room temperature.
The exploration of efficient electrocatalysts is the central issue for boosting the overall efficiency of water splitting. Herein, pertinently creating active sites and improving conductivity for ...metal–organic frameworks (MOFs) is proposed to tailor electrocatalytic properties for overall water splitting. An Ni(II)‐MOF nanosheet array is presented as an ideal material model and a facile alkali‐etched strategy is developed to break its NiO bonds accompanied with the introduction of extra‐framework K cations, which contribute to creating highly active open metal sites and largely improving the electrical conductivity. As a result, the assembled defect‐Ni‐MOF||defect‐Ni‐MOF electrolyte cell delivers a lower and stable voltage of 1.50 V at 10 mA cm−2 in alkaline medium for overall water splitting, comparable to the combination of iridium and platinum as benchmark catalysts.
The introduction of defects into metal–organic framework (MOF) by alkali‐etching treatment to create rich active sites and tailor electrical conductivity is proposed. The resultant defect‐rich Ni(II)‐MOF nanosheet array exhibits excellent electrocatalytic overall water splitting performance, comparable to the noble metal‐based benchmark catalysts.
For successful wastewater reclamation, advanced oxidation processes have attracted attention for elimination of emerging contaminants. In this study, the synergistic treatment with UV irradiation and ...chlorine (UV/chlorine) was used to degrade carbamazepine (CBZ). Neither UV irradiation alone nor chlorination alone could efficiently degraded CBZ. UV/chlorine oxidation showed a significant synergistic effect on CBZ degradation through generation of radical species (OH and Cl), and this process could be well depicted by pseudo first order kinetic. The degradation rate constants (kobs,CBZ) of CBZ increased linearly with increasing UV irradiance and chlorine dosage. The degradation of CBZ by UV/chlorine in acidic solutions was more efficient than that in basic solutions mainly due to the effect of pH on the dissociation of HOCl and OCl− and then on the quantum yields and radical species quenching of UV/chlorine. When pH was increased from 5.5 to 9.5, the rate constants of degradation of CBZ by OH decreased from 0.65 to 0.14 min−1 and that by Cl decreased from 0.40 to 0.11 min−1. The rate constant for the reaction between Cl and CBZ was 5.6 ± 1.6 × 1010 M−1 s−1. Anions of HCO3− (1–50 mM) showed moderate inhibition of CBZ degradation by UV/chlorine, while Cl− did not. UV/chlorine could efficiently degrade CBZ in wastewater treatment plant effluent, although the degradation was inhibited by about 30% compared with that in ultrapure water with chlorine dosage of 0.14–0.56 mM. Nine main oxidation products of the CBZ degradation by UV/chlorine were identified using the HPLC-QToF MS/MS. Initial oxidation products arose from hydroxylation, carboxylation and hydrogen atom abstraction of CBZ by OH and Cl, and were then further oxidized to generate acylamino cleavage and decarboxylation products of acridine and acridione.
•UV/chlorine showed synergistic degradation of carbamazepine than UV and chlorination.•Carbamazepine degraded through both OH and Cl ways during UV/chlorine oxidation•Carbamazepine could be efficiently degraded by UV/chlorine in UPW and WWTP effluent.•The second order rate constant between carbamazepine and Cl were examined
Single‐ligand‐based electronically conductive porous coordination polymers/metal–organic frameworks (EC‐PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their ...limited tunability in terms of both conductivity and topology. In this study, a new 2D π‐conjugated EC‐MOF containing copper units with mixed trigonal ligands was developed: Cu3(HHTP)(THQ) (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene, THQ=tetrahydroxy‐1,4‐quinone). The modulated conductivity (σ≈2.53×10−5 S cm−1 with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m2 g−1) of the Cu3(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor.
Makes sense: As two ligands offer more opportunity than one to tune MOF conductivity and topology, a 2D π‐conjugated copper‐based electronically conductive MOF with two different trigonal organic ligands was developed (see structure). The semiconductivity and high porosity of the resulting nanowires provided a low conductivity baseline and highly accessible surface areas, thus resulting in excellent room‐temperature chemiresistive sensing properties.
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