Evolutionary history of the angiosperm flora of China.

High species diversity may result from recent rapid speciation in a 'cradle' and/or the gradual accumulation and preservation of species over time in a 'museum'. China harbours nearly 10% of angiosperm species worldwide and has long been considered as both a museum, owing to the presence of many species with hypothesized ancient origins, and a cradle, as many lineages have originated as recent topographic changes and climatic shifts-such as the formation of the Qinghai-Tibetan Plateau and the development of the monsoon-provided new habitats that promoted remarkable radiation. However, no detailed phylogenetic study has addressed when and how the major components of the Chinese angiosperm flora assembled to form the present-day vegetation. Here we investigate the spatio-temporal divergence patterns of the Chinese flora using a dated phylogeny of 92% of the angiosperm genera for the region, a nearly complete species-level tree comprising 26,978 species and detailed spatial distribution data. We found that 66% of the angiosperm genera in China did not originate until early in the Miocene epoch (23 million years ago (Mya)). The flora of eastern China bears a signature of older divergence (mean divergence times of 22.04-25.39 Mya), phylogenetic overdispersion (spatial co-occurrence of distant relatives) and higher phylogenetic diversity. In western China, the flora shows more recent divergence (mean divergence times of 15.29-18.86 Mya), pronounced phylogenetic clustering (co-occurrence of close relatives) and lower phylogenetic diversity. Analyses of species-level phylogenetic diversity using simulated branch lengths yielded results similar to genus-level patterns. Our analyses indicate that eastern China represents a floristic museum, and western China an evolutionary cradle, for herbaceous genera; eastern China has served as both a museum and a cradle for woody genera. These results identify areas of high species richness and phylogenetic diversity, and provide a foundation on which to build conservation efforts in China.

New insights into the link between pro-environmental attitudes and household food waste behaviours in China: Moderating effect of shopping distance.

Environmental attitude, value and awareness are widely believed to help reach the goal of cutting global food waste, but these psychological and cognitive factors are not always good predictors of wasteful behaviours. Notably, it is still unclear how the role of pro-environmental attitude (PEA) in reducing household food waste (HFW) changes with grocery shopping distance. To this end, using 7319 households survey data from China, this study investigates the moderating effect of shopping distance on the link between PEA and HFW behaviour. The results of Tobit regressions show that PEA is an important predictor of actual HFW behaviour in the absence of the constraint of shopping distance. However, the expansion of shopping distance will weaken the positive role of PEA in reducing HFW. It indicates that, due to the temporal and financial constraints generated by shopping distance, there is a certain degree of hypothetical deviation between the wasteful behaviours that individuals actually exhibit and their stated PEA. Our findings, from the perspective of the moderating effect of shopping distance, explain why some individuals deviate from their stated PEA in HFW behaviour, which provides a new insight into the generation of 'attitude-behaviour' gap. Therefore, policy interventions that merely enhancing environmental education may have limited effect on reducing food waste; instead, the promotion of citizen environmental ethics should be combined with efforts to improve the accessibility of retail infrastructures.

Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation.

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies. However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China. We conducted a spatial phylogenetic analysis of the Chinese angiosperm flora at the generic level to identify centers of neo- and paleo-endemism. Our results indicate that: (i) the majority of grid cells in China with significantly high phylogenetic endemism (PE) were located in the mountainous regions; (ii) four of the nine centers of endemism recognized, located in northern and western China, were recognized for the first time; (iii) arid and semiarid regions in Northwest China were commonly linked to significant PE, consistent with other spatial phylogenetic studies worldwide; and (iv) six high-priority conservation gaps were detected by overlaying the boundaries of China's nature reserves on all significant PE cells. Overall, we conclude that the mountains of southern and northern China contain both paleo-endemics (ancient relictual lineages) and neo-endemics (recently diverged lineages). The areas we highlight as conservation priorities are important for broad-scale planning, especially in the context of evolutionary history preservation.

The Cyclic Hydrogen-Bonded 6-Azaindole Trimer and its Prominent Excited-State Triple-Proton-Transfer Reaction.

The compound 6-azaindole undergoes self-assembly by formation of N(1)-H⋅⋅⋅N(6) hydrogen bonds (H bonds), forming a cyclic, triply H-bonded trimer. The formation phenomenon is visualized by scanning tunneling microscopy. Remarkably, the H-bonded trimer undergoes excited-state triple proton transfer (ESTPT), resulting in a proton-transfer tautomer emission maximized at 435 nm (325 nm of the normal emission) in cyclohexane. Computational approaches affirm the thermodynamically favorable H-bonded trimer formation and the associated ESTPT reaction. Thus, nearly half a century after Michael Kasha discovered the double H-bonded dimer of 7-azaindole and its associated excited-state double-proton-transfer reaction, the triply H-bonded trimer formation of 6-azaindole and its ESTPT reaction are demonstrated.

The In Situ Tryptophan Analogue Probes the Conformational Dynamics in Asparaginase Isozymes.

Dynamic water solvation is crucial to protein conformational reorganization and hence to protein structure and functionality. We report here the characterization of water dynamics on the L-asparaginase structural homology isozymes L-asparaginases I (AnsA) and II (AnsB), which are shown via fluorescence spectroscopy and dynamics in combination with molecular dynamics simulation to have distinct catalytic activity. By use of the tryptophan (Trp) analog probe 2,7-diaza-tryptophan ((2,7-aza)Trp), which exhibits unique water-catalyzed proton-transfer properties, AnsA and AnsB are shown to have drastically different local water environments surrounding the single Trp. In AnsA, (2,7-aza)Trp exhibits prominent green N(7)-H emission resulting from water-catalyzed excited-state proton transfer. In stark contrast, the N(7)-H emission is virtually absent in AnsB, which supports a water-accessible and a water-scant environment in the proximity of Trp for AnsA and AnsB, respectively. In addition, careful analysis of the emission spectra and corresponding relaxation dynamics, together with the results of molecular dynamics simulations, led us to propose two structural states associated with the rearrangement of the hydrogen-bond network in the vicinity of Trp for the two Ans. The water molecules revealed in the proximity of the Trp residue have semiquantitative correlation with the observed emission spectral variations of (2,7-aza)Trp between AnsA and AnsB. Titration of aspartate, a competitive inhibitor of Ans, revealed an increase in N(7)-H emission intensity in AnsA but no obvious spectral changes in AnsB. The changes in the emission profiles reflect the modulation of structural states by locally confined environment and trapped-water collective motions.

Screening of peroxynitrite scavengers in Flos Lonicerae by using two new methods, an HPLC-DAD-CL technique and a peroxynitrite spiking test followed by HPLC-DAD analysis.

INTRODUCTION: Peroxynitrite is involved in the pathogenesis of a number of significant diseases. Peroxynitrite scavengers thus have potential application in understanding and treating these diseases. It is, therefore, important to establish screening methods able to rapidly identify peroxynitrite scavengers from herbal plants. OBJECTIVE: To develop effective and easily operable screening methods for identifying peroxynitrite scavengers in complex matrices, including Chinese herbal medicines. METHODS: Two simple and efficient screening methods have been developed for the identification of natural peroxynitrite scavengers in Flos Lonicerae Japonicae (FLJ). Method I used HPLC-DAD-(luminol-peroxynitrite)-CL techniques combined with Q-TOF MS/MS analysis, while Method II used pre-column reaction of the sample with peroxynitrite, followed by HPLC separation and Q-TOF MS/MS analysis. RESULTS: Five peroxynitrite scavengers (neochlorogenic acid, chlorogenic acid, 3,4-O-dicaffeoyl quinic acid, 3,5-O-dicaffeoyl quinic acid and 4,5-O-dicaffeoyl quinic acid) were identified in FLJ using Method I. Besides the compounds identified using Method I, three additional peroxynitrite scavengers (rutin, isoquercitrin and luteoloside) were identified using Method II. CONCLUSION: The two new methods proved to be complementary and the use of these methods should allow rapid detection of peroxynitrite-scavenging natural products from FLJ and other complex matrices.

[The Research of Spectral Polarization Imaging Detection System Based Dual-AOTFs].

Acousto-optic tunable filter (AOTF) has the advantages of small size, good stability, wide range of wavelength scanning, quick modulation speed and so on. So AOTF is widely used in spectral imaging. But the detection of spectral polarization imaging is seldom found by using AOTF individually., Anew method of spectral polarization imaging based on dual-AOTFs is proposed. This method shows that the incident light is firstly divided into two beams by splitting mirror, and then two beams of light are through two AOTFs respectively, and the polarization direction of +1 diffraction order formed by AOTF is at a 45° against the other. The intensity of 0°, 45°, 90°and 135° can be obtained by ±1 diffraction orders of dual-AOTFs. Finally, the Stokes parameters are obtained by ±1 diffraction orders imaging of dual-AOTFs. They are S0 (the sum of light intensity between 0° and 90°), S1(the difference of light intensity between 0° and 90°) and S2 (the difference of light intensity between 45° and 135°). The target degree of linear polarization (DoLP) and angle of linear polarization (AoLP) is realized by corresponding theoretical formula. Furthermore, the polarization imaging of different wavelengths is realized with frequency sweep of dual-AOTFs so as to ultimately detect the spectral polarization imaging. The experiment has been verified through polarization imaging of three different lights, such as λ=500 nm, λ=550 nm and λ=600 nm.

[The Study of Large OPD's PEM Based on Micro Trapezoidal Photo-Elastic Crystals].

Existing Photoelastic Modulator (PEM), whose optical path difference (OPD) is small, has strict requirements on the incident spot size and is poor in the aspect of light use efficiency under multiple reflections. What's more, Photoelastic Modulator based Fourier transform spectrometer (PEM-FTS) spectral resolution is relatively poor. Because there are these disadvantages in the PEM, this paper presents a method of large optical path difference whose PEM is based on micro trapezoidal photoelastic crystals. By improving the structure of photoelastic crystal, the PEM becomes micro trapezoidal octagonal structure. And two transmission surfaces are changed slightly into a certain angle. Therefore, the PEM improved can not only increase the optical path difference of the PEM, but also have less requirements on the incident spot size. Firstly, a detailed analysis of the maximum modulation optical path difference was made in this paper. Secondly, the equation of maximum optical path difference was deduced under any angle and any position of incident light, vibration displacement and stress distribution of PEM are analyzed by the way of COMSOL Multiphysics 4.3a. Again, a method was analyzed to find the best angle of incidence, combining with maximum optical path difference and energy efficiency. Then the large OP's PEM is designed and processed, including two parts: photoelastic crystal and piezoelectric crystal. Moreover, ZnSe crystal is used as photoelastic crystal, and piezoelectric quartz crystal is used as piezoelectric crystal. With experiment analyzed by 632. 8 nm He-Ne laser, the results show that under the same driving voltage, the optical path difference of the PEM improved is about 19. 25 times bigger than the normal PEM, and the relative error is 1.3%.

[The study of photo-elastic modulator-based Fourier transform spectroscopy].

In order to enhance the spectrum resolution of current photo-elastic modulator-based Fourier transform spectrometer, a multi-reflected photo-elastic modulator-based interferometer structure was proposed in the present paper. Through coating reflecting film alternatingly on the photo-elastic crystal and light oblique incidence, and allowing the incident ray to have the multi-reflection in the crystal and exit from the other side of the crystal, the authors increased the light propagation distance in the crystal and enhanced the optical path difference at last. Based on this, the function of interference-spectrum retrieval was established, the optical system matched to the multi-reflected PEM-based interferometer was designed, and finally, the experimental system of multi-reflected PEM-based Fourier transform spectroscopy for telemetry was established. The principle of verification tests by using 671 nm laser and xenon lamp shows that the interferogram was clear and stable, and the feasibility of the principle of the system was verified. The expected result shows that the spectrum resolution of the designed PEM-FTs with multi-reflection achieved 13 cm(-1), and its luminous flux just didn't reduce too much, which ensured the SNR. Through spectral inversion of the interference fringes, the technical feasibility of the spectrum system developed was verified. This work established the basic condition of prototype fabrication, radiation precise calibration, spectral calibration and instrument signal-to-noise ratio test and so on.

[Research of dual-photoelastic-modulator-based beat frequency modulation and Fourier-Bessel transform imaging spectrometer].

As the existing photoelastic-modulator(PEM) modulating frequency in the tens of kHz to hundreds of kHz between, leading to frequency of modulated interference signal is higher, so ordinary array detector cannot effectively caprure interference signal..A new beat frequency modulation method based on dual-photoelastic-modulator (Dual-PEM) and Fourier-Bessel transform is proposed as an key component of dual-photoelastic-modulator-based imaging spectrometer (Dual-PEM-IS) combined with charge coupled device (CCD). The dual-PEM are operated as an electro-optic circular retardance modulator, Operating the PEMs at slightly different resonant frequencies w1 and w2 respectively, generates a differential signal at a much lower heterodyne frequency that modulates the incident light. This method not only retains the advantages of the existing PEM, but also the frequency of modulated photocurrent decreased by 2-3 orders of magnitude (10-500 Hz) and can be detected by common array detector, and the incident light spectra can be obtained by Fourier-Bessel transform of low frequency component in the modulated signal. The method makes the PEM has the dual capability of imaging and spectral measurement. The basic principle is introduced, the basic equations is derived, and the feasibility is verified through the corresponding numerical simulation and experiment. This method has' potential applications in imaging spectrometer technology, and analysis of the effect of deviation of the optical path difference. This work provides the necessary theoretical basis for remote sensing of new Dual-PEM-IS and for engineering implementation of spectra inversion.

Effect of agricultural fiscal expenditures on agricultural carbon intensity in China.

Few studies provide direct evidences that agricultural fiscal affects agricultural carbon intensity. This study tries to fill this gap. Using panel data of 30 provinces in China from 2005 to 2019, we conclude that agricultural fiscal expenditures significantly reduce agricultural carbon intensity. The result is still robust after employing the provincial agricultural leaders' birthplace information as an instrumental variable. Further study shows that the negative effect of agricultural fiscal expenditures on agricultural carbon intensity is more pronounced in regions with less corruption and is also more visible in central, western, and inland regions than other areas. For this effect, agricultural technological improvement and structure optimization are possible channels, but not operation scale expansion. Interestingly, although agricultural fiscal expenditures reduce the local agricultural carbon intensity, neighbor regions' carbon intensities are increased due to fiscal rivalry.

[Temperature compensation strategy and implementation for photoelectric modulation interferometer with large optical path difference].

For temperature drift in hypervelocity photoelectric modulation interferometer, a control model of temperature compensation is presented including voltage and phase compensation. First, according to the similar and modeling theory, an equivalent circuit model of mechanical properties of hypervelocity photoelectric modulation interferometer was established, the impact of temperature drift on its resonance frequency was analyzed, a mathematical model was set up, which contains drive voltage, frequency and resonance frequency, and the control method was determined for high optical path difference to get steady. Then, a digital method including voltage and phase compensation is given for optical path difference deviation control, which merges the DPLL and program of voltage and phase compensation. Finally, the control method was tested through experiment system. A test between drive control system including voltage and phase compensation and traditional drive control system was executed, using a laser doppler vibrometer to record the amount of change in optical path difference within 3 hours. Results show that the optical path difference deviation caused by temperature drift in long term is reduced by about 50%.

Economic Growth, Income Inequality and Food Safety Risk.

Food safety risk, as an implicit cost of social and economic development, endangers the health of global residents, including China. To systematically understand the impact of socioeconomic development on food safety risk and to establish a sound modern governance system of food safety in China, this paper uses provincial panel data from 2011 to 2020 to explore the relationship between food safety risk and socio-economic development factors such as economic growth and income inequality by employing a two-way fixed effect model and moderating effect model. The results show that the food safety risk is a Kuznets curve, and the turning point is about RMB 58,104.59 per capita GDP (based on prices in 2011). However, under the moderating effect of income inequality, the turning point of the Kuznets curve of food safety risk will shift to the right, and the curve will be flattened. In other words, income inequality has a negative moderating effect on the "inverted U-shaped" relationship between economic growth and food safety risk. When dealing with food safety problems, the goal of stable and sustained economic growth and common prosperity should be incorporated into policy formulation to enhance the governance effectiveness of food safety risk.

Effects of Governmental Intervention on Foodborne Disease Events: Evidence from China.

Foodborne disease events (FDEs) endanger residents' health around the world, including China. Most countries have formulated food safety regulation policies, but the effects of governmental intervention (GI) on FDEs are still unclear. So, this paper purposes to explore the effects of GI on FDEs by using Chinese provincial panel data from 2011 to 2019. The results show that: (i) GI has a significant negative impact on FDEs. Ceteris paribus, FDEs decreased by 1.3% when government expenditure on FDEs increased by 1%. (ii) By strengthening food safety standards and guiding enterprises to offer safer food, government can further improve FDEs. (iii) However, GI has a strong negative externality. Although GI alleviates FDEs in local areas, it aggravates FDEs in other areas. (iv) Compared with the eastern and coastal areas, the effects of GI on FDEs in the central, western, and inland areas are more significant. GI is conducive to ensuring Chinese health and equity. Policymakers should pay attention to two tasks in food safety regulation. Firstly, they should continue to strengthen GI in food safety issues, enhance food safety certification, and strive to ensure food safety. Secondly, they should reinforce the co-governance of regional food safety issues and reduce the negative externality of GI.

Combining the species-area-habitat relationship and environmental cluster analysis to set conservation priorities: a study in the Zhoushan Archipelago, China.

Identification of priority areas is a fundamental goal in conservation biology. Because of a lack of detailed information about species distributions, conservation targets in the Zhoushan Archipelago (China) were established on the basis of a species-area-habitat relationship (choros model) combined with an environmental cluster analysis (ECA). An environmental-distinctness index was introduced to rank areas in the dendrogram obtained with the ECA. To reduce the effects of spatial autocorrelation, the ECA was performed considering spatial constraints. To test the validity of the proposed index, a principal component analysis-based environmental diversity approach was also performed. The priority set of islands obtained from the spatially constrained cluster analysis coupled with the environmental-distinctness index had high congruence with that from the traditional environmental-diversity approach. Nevertheless, the environmental-distinctness index offered the advantage of giving hotspot rankings that could be readily integrated with those obtained from the choros model. Although the Wilcoxon matched-pairs test showed no significant difference among the rankings from constrained and unconstrained clustering process, as indicated by cophenetic correlation, spatially constrained cluster analysis performed better than the unconstrained cluster analysis, which suggests the importance of incorporating spatial autocorrelation into ECA. Overall, the integration of the choros model and the ECA showed that the islands Liuheng, Mayi, Zhoushan, Fodu, and Huaniao may be good candidates on which to focus future efforts to conserve regional biodiversity. The 4 types of priority areas, generated from the combination of the 2 approaches, were explained in descending order on the basis of their conservation importance: hotspots with distinct environmental conditions, hotspots with general environmental conditions, areas that are not hotspots with distinct environmental conditions, and areas that are not hotspots with general environmental conditions.

Avian biogeography and conservation on Hainan Island, China.

The aim of this study was to perform a biogeographical and conservation analysis of avian distribution on Hainan Island, China using quantitative approaches. I employed cluster analysis with a statistical test to examine the biogeographical zonation of birds on Hainan Island, and then employed an optimization criterion approach to detect candidate areas of endemism. Three biogeographical regions were diagnosed based on the statistical tests. One area of endemism was identified in the southwestern part of the island, principally in the western limestone areas and the central mountainous areas. Canonical variate analysis showed significant separation among the three biogeographic regions correlated with climatic variables. Nested subset analysis using two null models indicated that there was a good nested pattern in the avian assemblage on Hainan Island. In addition, complementarity analysis identified six top species-rich provinces for conservation. The present study is one of the first attempts to use integrative quantitative approaches to analyze bird diversity patterns on this island, and the effectiveness of the methodologies employed is discussed.

Integrated chemometric fingerprints of antioxidant activities and HPLC-DAD-CL for assessing the quality of the processed roots of Polygonum multiflorum Thunb. (Heshouwu).

BACKGROUND: The processed roots of Polygonum multiflorum Thunb. (Heshouwu; processed HSW) are commonly used in anti-aging medicine. Few reports have combined chemical profiles with bioactivity to evaluate the quality of the processed HSW. This study aims to integrate chemometric fingerprints of antioxidant activities and high-performance liquid chromatography-diode array detection-chemiluminescence (HPLC-DAD-CL) to assess the quality of processed HSW. METHODS: An online HPLC-DAD-CL based on the three reactive oxygen species (ROS), superoxide anion, hydrogen peroxide, and peroxynitriteanion, was developed to screen the potential anti-aging constituents for a comprehensive quality evaluation of processed HSW. Additionally, antioxidant-activity-integrated fingerprints were constructed and hierarchical cluster analysis and principal component analysis were used to evaluate the variations among 14 batches of processed HSW samples purchased from drug stores in different habitats. RESULTS: Fourteen batches of processed HSW samples were highly similar and classified into two clusters using hierarchical cluster analysis. Twelve active compounds exhibited antioxidant activity on the ROS with different degrees of sensitivity that constituted specific fingerprints. Among them, protocatechuic acid, catechin, trans-2,3,5,4'-tetrahydroxy-stilbene-2-O-ß-d-glucoside, 2,3,5, 4'-tetrahydroxy-stilbene-2-O-ß-d-(2''-galloyl)-glucoside, torachrysone-8-O-glucoside, and emodin-8-O-ß-d-glucoside exerted relatively large influences on the differences between processed HSW samples. CONCLUSION: Our study established the antioxidative activity-integrated fingerprint for processed HSW and achieved a screening of the potential anti-aging constituents using the online HPLC-DAD-CL method with H2O2, O2 (•-), and ONOO(-)scavenging experiments.

A new series of fluorescent indicators for super acids.

The photophysical properties of fluorescent Hammett acidity indicator derived from 3,4,5,6-tetrahydrobis(pyrido[3,2-g]indolo)[2,3-a:3',2'-j]acridine (1a), 6-bis(pyrido[3,2-g]indol-2'-yl)pyridine (1b) and their analogues have been investigated in sulfuric acid solutions by means of absorption, fluorimetry, relaxation dynamics and computational approach. These new indicators undergo a reversible protonation process in the Hammett acidity range of H0 < 0, accompanied by a drastic increase of the bright blue-green (1a) or yellow (1b) fluorescence intensity upon increasing the acidity. For 1a in H2 SO4 , the emission yield increases as large as 200 folds from pH = -0.41 to the Hammett acidity range of -5.17, the results of which are rationalized by a much increase of the steric hindrance upon third protonation toward the central pyridinic site, together with their accompanied changes of electronic configuration from charge transfer to a delocalized ππ* character in the lowest lying excited state. The combination of 1a and 1b renders a wide and linear range of H0 measurement from -1.2 to -5.1 detected by highly intensive fluorescence.

Water-catalyzed excited-state proton-transfer reactions in 7-azaindole and its analogues.

The mechanism of the water-catalyzed excited-state proton-transfer (ESPT) reaction for 7-azaindole (7AI) has long been investigated, but there are some controversial viewpoints. Recently, owing to the superiority of sensing biowaters in proteins by a 7AI analogue, 2,7-diazatryptophan, it is timely to reinvestigate water-catalyzed ESPT in 7AI and its analogues in an attempt to unify the mechanism. Herein, a series of 7AI analogues and their methylated derivatives were synthesized to carry out a systematic study on pKa, pKa*, and the associated fluorescence spectroscopy and dynamics. The results conclude that all 7AI derivatives undergo water-catalyzed ESPT in neutral water. However, for those derivatives with -H (7AI) and a electron-donating substituent at C(3), they follow water-catalyzed ESPT to form an excited N(7)-H proton-transfer tautomer, T*. T* is rapidly protonated to generate an excited cationic (TC*) species. TC* then undergoes a fast deactivation to the N(1)-H normal species in the ground state. Conversely, protonation in T* is prohibited for those derivatives with an electron-withdrawing group at the C(2) or C(3) or with the C(2) atom replaced by an electron-withdrawing nitrogen atom (N(2) in, e.g., 2,7-diazatryptophan), giving a prominent green T* emission. Additional support is given by the synthesis of the corresponding N(7)-CH3 tautomer species, for which pKa* of the cationic form, that is, the N(7)-CH3N(1)-H(+) species, is measured to be much greater than 7.0 for those with electron-donating C(3) substituents, whereas it is lower than 7.0 upon anchoring electron-withdrawing groups. For 7AI, the previously missing T* emission is clearly resolved with a peak wavelength at 530 nm in the pH interval of 13.0-14.3 (H- 14.2).