In recent years melatonin has emerged as a research highlight in plant studies. Melatonin has different functions in many aspects of plant growth and development. The most frequently mentioned ...functions of melatonin are related to abiotic stresses such as drought, radiation, extreme temperature, and chemical stresses. This review mainly focuses on the regulatory effects of melatonin when plants face harsh environmental conditions. Evidence indicates that environmental stress can increase the level of endogenous melatonin in plants. Overexpression of the melatonin biosynthetic genes elevates melatonin levels in transgenic plants. The transgenic plants show enhanced tolerance to abiotic stresses. Exogenously applied melatonin can also improve the ability of plants to tolerate abiotic stresses. The mechanisms by which melatonin alleviates abiotic stresses are discussed.
Surface oxygen chemistry of semiconductor metal oxides is the basis for the sensing reaction between the preadsorbed surface oxygen and the target gases or organic vapors that are to be detected, and ...thus fundamentally determines their sensing performances. Herein, we, for the first time, identify a novel semiconductor spinel oxide, CdGa2O4, that has suitable surface oxygen chemistry and exhibits excellent selectivity and response toward formaldehyde. Moreover, we find that a cation off-stoichiometric CdGa2O4 spinel oxide decorated with a small amount of CdO nanocrystals can further improve the formaldehyde response, without losing the selectivity. This is based on the advantages of an increased amount of adsorbed oxygen in the Ga-rich environment, as well as heterojunctions between CdO nanoparticles and Ga-rich spinel oxide. Sensing performance (e.g., selectivity and response) of the material is much better than that of most reported nanostructured metal oxides used for formaldehyde detection. Our findings propose a general approach for achieving highly selective and sensitive detection of target gases by optimizing the surface oxygen property of semiconductor oxides.
This paper proposes a wide bandpass filter (BPF) with high out‐of‐band suppression and wide stop‐band characteristics. An interdigital coupled line structure loaded by a rectangular resonator ring is ...employed to generate three transmission poles in the pass‐band and an additional transmission zero (TZ) in the stop‐band, thereby achieving a wider pass‐band while enhancing stop‐band suppression. Compared to traditional coupled‐line structures, the structure mentioned in this paper offers significant advantages in designing filters with wide stop‐bands and high out‐of‐band suppression. Furthermore, open‐circuit T‐stub, and a pair of open‐circuit stub are used to generate multiple parasitic TZs at high frequencies, which is adopted to further expand the stop‐band range. Measurement results shows that the insertion loss of the BPF is of −2.86 dB within the range of 7.05–12.20 GHz. The stop‐band ranges from 13 to 48 GHz with an out‐of‐band suppression of −27 dB, especially when the out‐of‐band suppression is −40 dB, the stop‐band frequency range is 16.40–31.35 GHz.
The cation substitutional doping of metal oxide semiconductors plays pivotal roles in improving the gas sensing performances, but the doping effect on surface sensing reaction is still not well ...understood. In this study, indium oxides doped with various heteroatoms are investigated to obtain in-depth understanding of how doping (or the resulting change in the electronic structure) alters the surface-absorbed oxygen chemistry and subsequent sensing process. The experimental results reveal that energy level of In2O3 can be modulated by introduction of these dopants, some of which (e.g., Al, Ga, and Zr) lead to the elevation of Fermi level, whereas others (e.g., Ti, V, Cr, Mo, W, and Sn) bring about relative drop in Fermi level. However, only the former can improve the response to formaldehyde, indicating a strong link between Fermi level and sensing properties. Mechanistic study suggests that the elevation of Fermi level increases energy level difference between oxide semiconductor and oxygen molecules and facilitates the surface absorption of oxygen species, resulting in superior formaldehyde sensing activity. Especially, Al-doped In2O3 exhibits remarkably enhanced sensing performances toward formaldehyde at low working temperature (150 °C) with high response, good selectivity, ultralow limit of detection (60 ppb), and short response time (2–23 s). Our findings not only promote the understanding of sensing reaction process and its correlation with the semiconductor electronic structure but also offer a general guideline for large-scale screening of promising oxide semiconductor-based sensing materials for gas detection.
Patients with N2–3 nasopharyngeal carcinoma have a high risk of treatment being unsuccessful despite the current practice of using a concurrent adjuvant cisplatin–fluorouracil regimen. We aimed to ...compare the efficacy and safety of concurrent adjuvant cisplatin–gemcitabine with cisplatin–fluorouracil in N2–3 nasopharyngeal carcinoma.
We conducted an open-label, randomised, controlled, phase 3 trial at four cancer centres in China. Eligible patients were aged 18–65 years with untreated, non-keratinising, stage T1–4 N2–3 M0 nasopharyngeal carcinoma, an Eastern Cooperative Oncology Group performance status score of 0–1, and adequate bone marrow, liver, and renal function. Eligible patients were randomly assigned (1:1) to receive concurrent cisplatin (100 mg/m2 intravenously) on days 1, 22, and 43 of intensity-modulated radiotherapy followed by either gemcitabine (1 g/m2 intravenously on days 1 and 8) and cisplatin (80 mg/m2 intravenously for 4 h on day 1) once every 3 weeks or fluorouracil (4 g/m2 in continuous intravenous infusion for 96 h) and cisplatin (80 mg/m2 intravenously for 4 h on day 1) once every 4 weeks, for three cycles. Randomisation was done using a computer-generated random number code with a block size of six, stratified by treatment centre and nodal category. The primary endpoint was 3-year progression-free survival in the intention-to-treat population (ie, all patients randomly assigned to treatment). Safety was assessed in all participants who received at least one dose of chemoradiotherapy. This study was registered at ClinicalTrials.gov, NCT03321539, and patients are currently under follow-up.
From Oct 30, 2017, to July 9, 2020, 240 patients (median age 44 years IQR 36–52; 175 73% male and 65 27% female) were randomly assigned to the cisplatin–fluorouracil group (n=120) or cisplatin–gemcitabine group (n=120). As of data cutoff (Dec 25, 2022), median follow-up was 40 months (IQR 32–48). 3-year progression-free survival was 83·9% (95% CI 75·9–89·4; 19 disease progressions and 11 deaths) in the cisplatin–gemcitabine group and 71·5% (62·5–78·7; 34 disease progressions and seven deaths) in the cisplatin–fluorouracil group (stratified hazard ratio 0·54 95% CI 0·32–0·93; log rank p=0·023). The most common grade 3 or worse adverse events that occurred during treatment were leukopenia (61 52% of 117 in the cisplatin–gemcitabine group vs 34 29% of 116 in the cisplatin–fluorouracil group; p=0·00039), neutropenia (37 32% vs 19 16%; p=0·010), and mucositis (27 23% vs 32 28%; p=0·43). The most common grade 3 or worse late adverse event (occurring from 3 months after completion of radiotherapy) was auditory or hearing loss (six 5% vs ten 9%). One (1%) patient in the cisplatin–gemcitabine group died due to treatment-related complications (septic shock caused by neutropenic infection). No patients in the cisplatin–fluorouracil group had treatment-related deaths.
Our findings suggest that concurrent adjuvant cisplatin–gemcitabine could be used as an adjuvant therapy in the treatment of patients with N2–3 nasopharyngeal carcinoma, although long-term follow-up is required to confirm the optimal therapeutic ratio.
National Key Research and Development Program of China, National Natural Science Foundation of China, Guangdong Major Project of Basic and Applied Basic Research, Sci-Tech Project Foundation of Guangzhou City, Sun Yat-sen University Clinical Research 5010 Program, Innovative Research Team of High-level Local Universities in Shanghai, Natural Science Foundation of Guangdong Province for Distinguished Young Scholar, Natural Science Foundation of Guangdong Province, Postdoctoral Innovative Talent Support Program, Pearl River S&T Nova Program of Guangzhou, Planned Science and Technology Project of Guangdong Province, Key Youth Teacher Cultivating Program of Sun Yat-sen University, the Rural Science and Technology Commissioner Program of Guangdong Province, and Fundamental Research Funds for the Central Universities.
We report herein the development of palladium‐catalyzed deacylative deuteration of arylketone oxime ethers. This protocol features excellent functional group tolerance, heterocyclic compatibility, ...and high deuterium incorporation levels. Regioselective deuteration of some biologically important drugs and natural products are showcased via Friedel–Crafts acylation and subsequent deacylative deuteration. Vicinal meta‐C−H bond functionalization (including fluorination, arylation, and alkylation) and para‐C−H bond deuteration of electro‐rich arenes are realized by using the ketone as both directing group and leaving group, which is distinct from aryl halide in conventional dehalogenative deuteration.
A palladium‐catalyzed deuteration of arylketone oxime ethers has been realized. Regioselective deuteration of some biologically important drugs and natural products is showcased via Friedel–Crafts acylation and subsequent deacylative deuteration. Vicinal difunctionalization of electro‐rich arenes is achieved by using the ketone as both directing group and leaving group.
Nasopharyngeal carcinoma (NPC) is a malignancy predominantly associated with infection by the Epstein-Barr virus (EBV). Approximately 12,900 new cases of NPC occur each year, with more than 70% of ...cases occurring in the east and southeast Asia. NPC is different from ordinary head and neck squamous cell carcinoma due to its particular biological properties and it is highly sensitive to radiotherapy. With the development of RT technology, the 3-year local control rate and survival rates of non-metastatic NPC reached 80-90% in the intensity-modulated RT (IMRT) era. However, whether distant metastatic NPC (de novo mNPC, dmNPC) should receive locoregional RT (LRRT) needs to be clarified.
Multivariate analysis identified three independent prognostic factors: Epstein-Barr virus (EBV) DNA, number of metastatic lesions, and number of metastatic organs. Through these factors, all patients were successfully divided into 3 subgroups: low-risk (single metastatic organ, EBV DNA ≤ 25,000 copies/ml, and ≤ 5 metastatic lesions), intermediate-risk (single metastatic organ, EBV DNA > 25,000 copies/ml, and ≤ 5 metastatic lesions), and high-risk (multiple metastatic organs or > 5 metastatic lesions or both). By comparing LRRT and non-LRRT groups, statistical differences were found in OS in the low-risk and intermediate-risk subgroups (p = 0.039 and p = 0.010, respectively) but no significant difference was found in OS in the high-risk subgroup (p = 0.076). Further multivariate analysis of different risk stratifications revealed that LRRT can improve OS of low- and intermediate-risk subgroups.
The risk stratification of dmNPC may be used as a new prognostic factor to help clinicians organize individualized LRRT treatment to improve the survival outcomes of dmNPC patients.
Gas hydrates have been endowed with great potential as the medium for natural gas storage & transportation. In this work, we prepared novel nanopromoters by grafting hydrophilic groups (SO3−, COO− ...and NCH33+) covalently on polystyrene nanospheres (Group@PSNS), and for the first time achieved rapid formation of methane hydrates together compact agglomeration by regulating the hydrophilic groups on the surface of nanopromoters. When SO3−@PSNS was used, methane hydrates formed rapidly but loosely in the reactor; while for COO−@PSNS and N(CH3)3+@PSNS, even the hydrate formation rate was seriously reduced, the formed hydrates agglomerated compactly in the reactor bottom. Interestingly, when both SO3− and COO− were fixed on the nanospheres, both the hydrate growth rate and agglomeration compactness were controlled. Especially, the nanopromoter with the SO3−/COO− molar ratio of 2:1 resulted in the formation of methane hydrates with compact agglomeration morphology within 1–2 hr and with the storage capacity reaching 140–145 vol/vol.
Tungsten (W) is the most commonly used high-temperature refractory metal in many critical fields such as aerospace, military and electronic industries etc. This paper proposes a low-cost, efficient, ...and industrially feasible pathway for large scale preparation of tungsten nanoparticles via the combination of carbothermic reduction and hydrogen reduction processes. The new strategy involves the preparation process of pre-reduction W powder by reducing commercial WO3 with insufficient carbon black at 1050 °C or 1150 °C to avoid the residue of carbon, and the deep reduction process of pre-reduction W powder by hydrogen 725 °C. By this process, most of the oxygen in WO3 was reduced by carbon, and W particles with a much smaller size could be obtained owing to the absence of the volatile tungsten oxide, such as WO2(OH)2, which leads to the serious increase of particle size during the hydrogen reduction process. Tungsten nanoparticles with average particle sizes of about 40 nm and 75 nm have been successfully synthesized at 1050 °C and 1150 °C, respectively, with the residual carbon content as low as about 0.01%. This process can be readily extended to a large-scale industrial production of W nanopowders. Additionally, this new strategy has great potential to prepare other pure metals (or nanopowders) from their metal oxides via combining of carbothermic reduction (main process) and further reduction of other reducing agents.
•Pre-reduced nano W powders were prepared by reducing WO3 with insufficient carbon.•Growth of W nanoparticles can be controlled in carbothermic reduction process.•A minor amount of remained WO2 can reduce the residual carbon to as low as 0.01%.•A deep deoxidation by H2 at 725 °C could reduce the minor amount of WO2 to W.
In the current study, ultrafine and high-purity tungsten carbide (WC) powders are successfully prepared by a two-step process: carbothermic reduction of WO3 followed by carbonization reaction. The ...effects of the C/WO3 molar ratio, reaction temperature and reaction time on the phase transition and morphology evolution of the products are investigated. During the carbothermic reduction process, all the oxygen in yellow tungsten trioxide (WO3) is removed by carbon to generate a mixture of W, W2C and WC at 1100 °C; and then the as-prepared powder is mixed with an appropriate content of carbon black and carbonized at 1200 °C. The carbon content in the finally obtained WC powders is almost equal to the theoretical value. Furthermore, it is found that a high C/WO3 molar ratio at the first stage is beneficial for decreasing the particle size of the WC powders. When the C/WO3 molar ratio is 3.5, the single phase WC with a particle size of about 200 nm can be obtained. Therefore, this carbothermic reduction–carburization process may provide a simple, low-cost, and high efficiency route to prepare the WC powders in a large-scale.
Display omitted
•Ultrafine WC are prepared by carbothermic reduction-carbonization process.•A high C/WO3 molar ratio could decrease the particle size of prepared WC.•A low carbonization temperature of 1200 °C is used to prepare WC.
PDF
