Herein, an effective tandem catalysis strategy is developed to improve the selectivity of the CO2RR towards C2H4 by multiple distinct catalytic sites in local vicinity. An earth‐abundant ...elements‐based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel–nitrogen sites (PTF(Ni)) for the enhanced CO2RR to produce C2H4. The Faradaic efficiency of C2H4 reaches 57.3 % at −1.1 V versus the reversible hydrogen electrode (RHE), which is about 6 times higher than the non‐tandem catalyst PTF/Cu, which produces CH4 as the major carbon product. The operando infrared spectroscopy and theoretic density functional theory (DFT) calculations reveal that the local high concentration of CO generated by PTF(Ni) sites can facilitate the C−C coupling to form C2H4 on the nearby Cu NP sites. The work offers an effective avenue to design electrocatalysts for the highly selective CO2RR to produce multicarbon products via a tandem route.
An effective tandem catalysis strategy is developed to enhance the selectivity of the CO2 electroreduction reaction towards C2H4 with a 6‐fold increase in comparison with that of the non‐tandem catalysts. The local high concentration of CO generated by atomically isolated nickel–nitrogen sites PTF(Ni) sites can facilitate the C−C coupling to form C2H4 on the nearby Cu NP sites, thus switching from CH4 to C2H4 production with a Faradaic efficiency of 57.3 %.
Covalent organic frameworks (COFs) are promising candidates for electrocatalytic reduction of carbon dioxide into valuable chemicals due to their porous crystalline structures and tunable single ...active sites, but the low conductivity leads to unmet current densities for commercial application. The challenge is to create conductive COFs for highly efficient electrocatalysis of carbon dioxide reduction reaction (CO2RR). Herein, a porphyrin‐based COF containing donor–acceptor (D–A) heterojunctions, termed TT‐Por(Co)‐COF, is constructed from thieno3,2‐bthiophene‐2,5‐dicarbaldehyde (TT) and 5,10,15,20‐tetrakis(4‐aminophenyl)‐porphinatocobalt (Co‐TAPP) via imine condensation reaction. Compared with COF‐366‐Co without TT, TT‐Por(Co)‐COF displays enhanced CO2RR performance to produce CO due to its favorable charge transfer capability from the electron donor TT moieties to the acceptor Co‐porphyrin ring active center. The combination of strong charge transfer properties and enormous amount of accessible active sites in the 2D TT‐Por(Co)‐COF nanosheets results in good catalytic performance with a high Faradaic efficiency of CO (91.4%, −0.6 V vs reversible hydrogen electrode (RHE) and larger partial current density of 7.28 mA cm−2 at −0.7 V versus RHE in aqueous solution. The results demonstrate that integration of D–A heterojunctions in COF can facilitate the intramolecular electron transfer, and generate high current densities for CO2RR.
A donor–acceptor heterojunctions is constructed in cobalt porphyrin‐based COF (TT‐Por(Co)‐COF) to enhance the current density of CO2 electroreduction reaction due to its favorable charge transfer capability. TT‐Por(Co)‐COF nanosheets show a high FECO of 91.4% at −0.6 V versus reversible hydrogen electrode (RHE) and large partial current density of 7.28 mA cm−2 at −0.7 V versus RHE in aqueous solution.
Organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) materials are promising for the realization of highly efficient light emitters. However, such devices ...have so far suffered from efficiency roll-off at high luminance. Here, we report the design and synthesis of two diboron-based molecules, CzDBA and tBuCzDBA, which show excellent TADF properties and yield efficient OLEDs with very low efficiency roll-off. These donor–acceptor–donor (D–A–D) type and rod-like compounds concurrently generate TADF with a photoluminescence quantum yield of ~100% and an 84% horizontal dipole ratio in the thin film. A green OLED based on CzDBA exhibits a high external quantum efficiency of 37.8 ± 0.6%, a current efficiency of 139.6 ± 2.8 cd A−1 and a power efficiency of 121.6 ± 3.1 lm W−1 with an efficiency roll-off of only 0.3% at 1,000 cd m−2. The device has a peak emission wavelength of 528 nm and colour coordinates of the Commission International de l´Eclairage (CIE) of (0.31, 0.61), making it attractive for colour-display applications.
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen ...acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system’s exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Two benzoylpyridine-carbazole based fluorescence materials DCBPy and DTCBPy, bearing two carbazolyl and 4-(t-butyl)carbazolyl groups, respectively, at the meta and ortho carbons of the benzoyl ring, ...were synthesized. These molecules show very small ΔE ST of 0.03 and 0.04 eV and transient PL characteristics indicating that they are thermally activated delayed fluorescence (TADF) materials. In addition, they show extremely different photoluminescent quantum yields in solution and in the solid state: in cyclohexane the value are 14 and 36%, but in the thin films, the value increase to 88.0 and 91.4%, respectively. The OLEDs using DCBPy and DTCBPy as dopants emit blue and green light with EQEs of 24.0 and 27.2%, respectively, and with low efficiency roll-off at practical brightness level. The crystal structure of DTCBPy reveals a substantial interaction between the ortho donor (carbazolyl) and acceptor (4-pyridylcarbonyl) unit. This interaction between donor and acceptor substituents likely play a key role to achieve very small ΔE ST with high photoluminescence quantum yield.
The host materials designed for highly efficient white phosphorescent organic light‐emitting diodes (PhOLEDs) with power efficiency (PE) >50 lm W‐1 and low efficiency roll‐off are very rare. In this ...work, three new indolocarbazole‐based materials (ICDP, 4ICPPy, and 4ICDPy) are presented composed of 6,7‐dimethylindolo3,2‐acarbazole and phenyl or 4‐pyridyl group for hosting blue, green, and red phosphors. Among this three host materials, 4ICDPy‐based devices reveal the best electroluminescent performance with maximum external quantum efficiencies (EQEs) of 22.1%, 27.0%, and 25.3% for blue (FIrpic), green (fac‐Ir(ppy)3), and red ((piq)2Ir(acac)) PhOLEDs. A two‐color and single‐emitting‐layer white organic light‐emitting diode hosted by 4ICDPy with FIrpic and Ir(pq)3 as dopants achieves high EQE of 20.3% and PE of 50.9 lm W−1 with good color stability; this performance is among the best for a single‐emitting‐layer white PhOLEDs. All 4ICDPy‐based devices show low efficiency roll‐off probably due to the excellent balanced carrier transport arisen from the bipolar character of 4ICDPy.
Three new indolocarbazole‐based host materials, ICDP, 4ICPPy, and 4ICDPy, are synthesized and used as hosts for various color phosphorescent organic light‐emitting diodes. The blue, green, and red devices using 4ICDPy as the host all exhibit very high device efficiencies. In addition, a two‐color white device shows an external quantum efficiency of 20.3% and power efficiency of 50.9 lm W−1 with excellent color stability.
Human papillomavirus (HPV) is the well‐established etiologic factor for cervical neoplasia. Cervical conization constitutes an effective treatment for high‐grade cervical intraepithelial neoplasia ...(HG‐CIN). We conducted an observational study for long‐term outcomes and HPV genotype changes after conization for HG‐CIN. Between 2008 and 2014, patients with newly diagnosed HG‐CIN before conization (surveillance new SN group) and those who had undergone conization without hysterectomy (surveillance previous SP group) were enrolled. HPV testing and Pap smear were performed periodically for the SN and SP (collectively S) groups. All other patients receiving conization for HG‐CIN during the study period were identified from our hospital database. Those eligible but not enrolled into our study were assigned to the non‐surveillance (non‐S) group. For the S group (n = 493), the median follow‐up period was 74.3 months. Eighty‐four cases had recurrent CIN Grade 2 or worse (CIN2+) (5‐year cumulative rate: 14.8%), of which six had invasive cancer. Among the 84 patients, 65 (77.4%) exhibited type‐specific persistence in the paired HPV results, whereas only 7 (8.3%) harbored new HPV types that belonged to the 9‐valent vaccine types. Among the 7397 non‐S patients, 789 demonstrated recurrent CIN2+, of which 57 had invasive cancer. The stages distribution of those progressed to invasive cancer in the non‐S group were more advanced than the S group (P = .033). Active surveillance might reduce the severity of those progressed to cancer. Because a majority of the patients with recurrent CIN2+ had persistent type‐specific HPV infections, effective therapeutic vaccines are an unmet medical need.
What's new?
High‐grade cervical intraepithelial neoplasia (HG‐CIN), a cervical carcinoma precursor, frequently is caused by high‐risk human papillomavirus (hr‐HPV) infection. HG‐CIN can be treated by cervical conization, though the procedure does not eradicate hr‐HPV, potentially enabling CIN recurrence. Here, in Taiwanese patients, investigation of HPV genotype changes in relation to HG‐CIN status after conization shows that 77.4 percent of patients with recurrent CIN 2 grade or worse (CIN2+) after conization had persistent type‐specific HPV infections. Vaccination against the remaining high‐risk HPVs prevented recurrent CIN2+ in only 8.3 percent of patients, revealing an unmet need for effective therapeutic vaccines.
With the promotion of Industry 4.0, which emphasizes interconnected and intelligent devices, several factories have introduced numerous terminal Internet of Things (IoT) devices to collect relevant ...data or monitor the health status of equipment. The collected data are transmitted back to the backend server through network transmission by the terminal IoT devices. However, as devices communicate with each other over a network, the entire transmission environment faces significant security issues. When an attacker connects to a factory network, they can easily steal the transmitted data and tamper with them or send false data to the backend server, causing abnormal data in the entire environment. This study focuses on investigating how to ensure that data transmission in a factory environment originates from legitimate devices and that related confidential data are encrypted and packaged. This paper proposes an authentication mechanism between terminal IoT devices and backend servers based on elliptic curve cryptography and trusted tokens with packet encryption using the TLS protocol. Before communication between terminal IoT devices and backend servers can occur, the authentication mechanism proposed in this paper must first be implemented to confirm the identity of the devices and, thus, the problem of attackers imitating terminal IoT devices transmitting false data is resolved. The packets communicated between devices are also encrypted, preventing attackers from knowing their content even if they steal the packets. The authentication mechanism proposed in this paper ensures the source and correctness of the data. In terms of security analysis, the proposed mechanism in this paper effectively withstands replay attacks, eavesdropping attacks, man-in-the-middle attacks, and simulated attacks. Additionally, the mechanism supports mutual authentication and forward secrecy. In the experimental results, the proposed mechanism demonstrates approximately 73% improvement in efficiency through the lightweight characteristics of elliptic curve cryptography. Moreover, in the analysis of time complexity, the proposed mechanism exhibits significant effectiveness.
Circulating tumor DNA (ctDNA) provides a potential non‐invasive biomarker for cancer diagnosis and prognosis, but whether it could reflect tumor heterogeneity and monitor therapeutic responses in ...hepatocellular carcinoma (HCC) is unclear. Focusing on 574 cancer genes known to harbor actionable mutations, we identified the mutation repertoire of HCC tissues, and monitored the corresponding ctDNA features in blood samples to evaluate its clinical significance. Analysis of 3 HCC patients' mutation profiles revealed that ctDNA could overcome tumor heterogeneity and provide information of tumor burden and prognosis. Further analysis was conducted on the 4th HCC case with multiple lesion samples and sequential plasma samples. We identified 160 subclonal SNVs in tumor tissues as well as matched peritumor tissues with PBMC as control. 96.9% of this patient's tissue mutations could be also detected in plasma samples. These subclonal SNVs were grouped into 9 clusters according to their trends of cellular prevalence shift in tumor tissues. Two clusters constituted of tumor stem somatic mutations showed circulating levels relating with cancer progression. Analysis of tumor somatic mutations revealed that circulating level of such tumor stem somatic mutations could reflect tumor burden and even predict prognosis earlier than traditional strategies. Furthermore, HCK (p.V174M), identified as a recurrent/metastatic related mutation site, could promote migration and invasion of HCC cells. Taken together, study of mutation profiles in biopsy and plasma samples in HCC patients showed that ctDNA could overcome tumor heterogeneity and real‐time track the therapeutic responses in the longitudinal monitoring.
What's new?
Hepatocellular carcinoma (HCC) is a heterogenous disease, with significant variability in morphology, molecular alterations, and progression. Accurately evaluating the prognosis of this complicated disease is challenging but could potentially overcome through the use of circulating tumor DNA (ctDNA), according to the present study. Analysis of mutation profiles in HCC patients showed that more than 98% of subclonal mutations are captured in ctDNA. The majority of changes in circulating levels of subclonal mutations were correlated to tumor burden. By providing real‐time information on tumor lesions, the screening of somatic ctDNA alterations could facilitate tumor burden tracking and enable earlier prognostic determination.
The highly selective production of reduced multicarbon products with long‐term durability for CO2 electroreduction reaction (CO2RR) using clean and renewable electricity is currently a major ...challenge. Copper nanoparticles (Cu NPs) are exceptionally advantageous for CO2RR to yield multielectron transfer chemical products such as ethylene and ethanol. However, Cu NPs for CO2RR generally require high overpotential to produce multiple electron transfer C2+ products with poor stability. Herein, an imidazolium‐functionalized covalent triazine framework (ICTF) stabilized Cu NPs (Cu/ICTF) for the enhanced CO2RR to produce ethylene is reported. The imidazolium groups in the cationic ICTF not only can enhance CO2 capture capacity and lower the energetic barrier to activate CO2, but also the in situ formed N‐heterocyclic carbenes (NHC) could stabilize Cu NPs to prevent their deactivation. Thus, the Cu/ICTF demonstrated higher selectivity (35 %) for the electroreduction of CO2 to ethylene with larger partial current density of ethylene (4.14 mA cm−2) over the unmodified neutral CTF stabilized Cu NPs (Cu/CTF) with 29 % Faradaic efficiency (FE) of ethylene and current density of 3.69 mA cm−2. Moreover, the active sites could be stabilized by the in situ produced NHC in ICTF and the current density and C2H4 FE of Cu/ICTF50 were almost maintained after 10 h continuous electrolysis experiment, while the C2H4 FE of Cu/CTF50 were lost ca. 42 % of its original value after 7 h. This strategy provides a facile approach to stabilize active sites for CO2RR and may bring new inspiration to apply in energy storage and conversion.
CO2 electroreduction: An imidazolium‐functionalized covalent triazine framework (ICTF) stabilized Cu NPs (Cu/ICTF) for the enhanced CO2RR to produce ethylene was reported. The imidazolium groups in the cationic ICTF not only can enhance CO2 capture capacity and lower energetic barrier to activate CO2, but also the in situ formed N‐heterocyclic carbenes (NHC) could stabilize Cu NPs to prevent their deactivation.
PDF
