1H Nuclear Magnetic Resonance (1H NMR) combined with multivariate statistics was adopted to discriminate female and male flower buds of Populus tomentosa in the study. Samples of 11 female and 16 ...male flower buds of P. tomentosa were collected in Beijing, China. 1H NMR spectra were acquired on a 400 MHz spectrometer. In total, 30 chemical compounds were identified with standards and literature according to chemical shifts, peak areas, and multiplicity. Principal component analysis (PCA), hierarchical clustering analysis (HCA), and supervised orthogonal partial least squares-discriminant analysis (OPLS-DA) were applied to discriminate female and male flower buds. An apparent grouping trend (R2X, 0.809; Q2, 0.903) between female and male groups was exhibited with PCA and HCA. The two groups were also well discriminated with OPLS-DA (R2X, 0.808; R2Y, 0.976; Q2, 0.960). Combined with variable importance in projection (VIP) > 1.0 and p < 0.05 of OPLS-DA, it was found that the content of daucosterol, β-sitosterol, ursolic acid, and betulonic acid in male group was higher than that in female, which should be the key differences of chemical constituents in female and male flower buds of P. tomentosa. The study demonstrated that 1H NMR combined with multivariate statistics could be used to discriminate female and male plants and clarify differences, which provided a novel method to identify the gender of dioecious plants.
In this paper, a finite-time sliding mode control scheme is proposed to realize the trajectory tracking control for a two degrees of freedom (DOFs) pneumatic dexterous finger. A nonlinear extended ...state observer (NESO) is designed to estimate model uncertainties and external disturbances. A nonsingular finite-time sliding mode controller (NFTSMC) is proposed to achieve fast tracking. Furthermore, stability analyses are shown on both the NESO and the NFTSMC based on Lyapunov methods. Finally, a series of trajectory tracking experiments are carried on a two DOFs pneumatic dexterous finger platform to demonstrate the effectiveness of the proposed finite-time sliding mode control scheme.
Recently, several intriguing interfacial phenomena have been discovered at the KTaO3 (111)-based heterointerfaces, such as the two-dimensional electron gas, superconductivity, anisotropic ...conductivity, etc. However, the available techniques to systematically manipulate such interfacial states are quite limited. Here, we devise a delta-doping strategy by inserting a sub-nanometer Ti layer with distinct reducibilities to the LaAlO3/KTaO3 (111) interface. In the delta-doped samples, we observe an unforeseen two-band conduction, evidenced by the emergence of a new type of electron carrier with an order-of-magnitude enhancement of mobility (∼1800 cm2V−1s−1) than the original carriers. Moreover, the appearance of the high-mobility carriers causes a sharp transition between the non-Fermi-liquid superconducting state and the Fermi-liquid state with reduced spin–orbit scattering. Further evidence shows that the new type of carriers stems from another in-gap state with a shallower energy level compared to the original carriers. Our study broadens the spectrum of interfacial carrier manipulation by introducing an extra band/channel for carrier conduction, which not only opens up new possibilities in device applications but also shines a light on the underlying physics of interfacial superconductivity.
Abstract
The excitonic insulator (EI) is a Bose-Einstein condensation (BEC) of excitons bound by electron-hole interaction in a solid, which could support high-temperature BEC transition. The ...material realization of EI has been challenged by the difficulty of distinguishing it from a conventional charge density wave (CDW) state. In the BEC limit, the preformed exciton gas phase is a hallmark to distinguish EI from conventional CDW, yet direct experimental evidence has been lacking. Here we report a distinct correlated phase beyond the 2×2 CDW ground state emerging in monolayer 1T-ZrTe
2
and its investigation by angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The results show novel band- and energy-dependent folding behavior in a two-step process, which is the signatures of an exciton gas phase prior to its condensation into the final CDW state. Our findings provide a versatile two-dimensional platform that allows tuning of the excitonic effect.
(Ser.) C. B. Clarke (Family Cucurbitaceae) is a dioecious plant and has been used as a traditional Tibetan medicine for the treatment of hepatobiliary diseases. The component, content, and difference ...in volatile compounds in the female and male buds of
were explored by using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology and multivariate statistical analysis. The results showed that isoamyl alcohol was the main compound in both female and male buds and its content in males was higher than that in females; 18 compounds were identified in female buds including 6 unique compounds such as (
)-4-hexenol and isoamyl acetate, and 32 compounds were identified in male buds, including 20 unique compounds such as (
)-3-methylbutyraldehyde oxime and benzyl alcohol. (
)-3-methylbutyraldehyde oxime and (
)-3-methylbutyraldehyde oxime were found in male buds, which only occurred in night-flowering plants. In total, 9 differential volatile compounds between female and male buds were screened out, including isoamyl alcohol, (
)-3-methylbutanal oxime, and 1-nitropentane based on multivariate statistical analysis such as principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA). This is the first time to report the volatile components of
, which not only find characteristic difference between female and male buds, but also point out the correlation between volatile compounds, floral odor, and plant physiology. This study enriches the basic theory of dioecious plants and has guiding significance for the production and development of
germplasm resources.
Objective
To explore whether narrow‐band imaging (NBI) endoscopy is accurate in the diagnosis of malignant transformation of vocal cord leukoplakia.
Methods
The PubMed, Embase, Cochrane Library and ...Web of Science databases were searched to collect data on studies reporting the use of NBI endoscopy as a diagnostic test for diagnosing vocal cord leukoplakia from January 2015 to December 2021. Study design, analysis method, and extraction results were performed according to the PRISMA guidelines. The sensitivity, specificity, pooled positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the curve (AUC) were used to summarize the performance metrics of the meta‐analysis. Risk of bias data and the quality of the included studies was evaluated according to the Quality Assessment of Diagnostic Accuracy Studies‐2 tool (QUADAS‐2).
Results
Nine studies were finally included in the analysis. The results of the meta‐analysis showed that the pooled sensitivity and specificity of NBI endoscopy for diagnosing leukoplakia lesions were 0.76 (95% CI: 0.72–0.8) and 0.93 (95% CI: 0.91–0.95), respectively. The PLR and NLR were 10.09 (95% CI: 6.53–15.59) and 0.22 (95% CI: 0.13–0.38), respectively. The comprehensive diagnostic odds ratio (DOR) was 54.96 (95% CI: 24.32–124.17), and the area under the curve was 0.9584. The eight articles had a low risk of bias risk and one article was unclear.
Conclusion
NBI likely has good accuracy for diagnosing malignant transformation of vocal cord leukoplakia. However, multicenter studies and large samples are still needed.
Narrow‐band imaging (NBI) likely has good accuracy for diagnosing malignant transformation of vocal cord leukoplakia and has a high diagnostic value. But the diagnostic value of NBI for leukoplakia needs to be further verified by multicenter, large sample, and high‐quality clinical trials.
The systematic advancement of land urbanization coupled with the pursuit of a low-carbon economy constitutes a critical challenge faced by numerous nations across the globe. Utilizing panel data ...spanning 195 countries from 1990 to 2020, this study employed a panel regression model to scrutinize the impact mechanisms of land urbanization on CO2 emissions across income groups. The findings revealed a consistent overall increase in both land urbanization and per capita CO2 emissions during the period examined, with marked disparities evident among countries of varying income levels. The regression analysis further identified an “inverted U-shaped” curve relationship between land urbanization and per capita CO2 emissions in the global context and within high-income panels. Conversely, a “U-shaped” curve relationship was discerned in lower-middle-income nations, whereas a linear relationship was observed in upper-middle-income and low-income countries. These insights serve to deepen the understanding of the CO2 emission implications of land urbanization across countries at different development stages. This study underscores the necessity for countries to attentively consider their unique stage of development when devising CO2 reduction policies, reinforcing the complex interplay between urbanization, economic categorization, and environmental stewardship.
We present a two-step technique for the synthesis of superconducting CuxBi2Se3. Cu0.15Bi2Se3 single crystals were synthesized using the melt-growth method. Although these samples are ...non-superconducting, they can be employed to generate high quality superconducting samples if used as precursors in the following electrochemical synthesis step. Samples made from Cu0.15Bi2Se3 reliably exhibit zero-resistance even under the non-optimal quenching condition, while samples made from pristine Bi2Se3 require fine tuning of the quenching conditions to achieve similar performance. Moreover, under the optimal quenching condition, the average superconducting shielding fraction was still lower in the samples made from pristine Bi2Se3 than in the samples made from Cu0.15Bi2Se3. These results suggest that the pre-doped Cu atoms facilitate the formation of a superconducting percolation network. We also discuss the useful clues that we gathered about the locations of Cu dopants that are responsible for superconductivity.
In digital marketing, the core advantages of scientific and technological means such as artificial intelligence and big data analysis gradually appear and pay attention to them. This paper studies ...the accuracy of digital marketing and proposes an intelligent algorithm based on data analysis, which improves the effect of marketing communication. Through the combination of intelligent algorithms and big data analysis, the data are convincing. Through the comparison and improvement of intelligent algorithm logistic regression and XGBoost, this paper puts forward an improved algorithm of XGBoost based on Bayesian optimization parameters, which can improve the efficiency of digital marketing communication and enhance the social influence of digital marketing.
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