Evaluation of Food Security in North China Based on Food Production Level.

This paper focuses on county-level grain production and food security in North China; selects 17 indicators from both climatic conditions and human activities; applies yield fluctuation coefficients, spatial econometric modelling, the random forest method, and factor analysis to study the characteristics of grain production in North China and the influencing factors; and evaluates the situation of food security in North China based on grain production capacity. The following results were obtained: (1) The spatial and temporal changes in grain production located in North China from 2000 to 2020 are obvious. The grain output in North China from 2000 to 2020 maintains fluctuating growth at a rate of 0.38 × 1011 kg/10a. The east and south are the key areas for grain production in North China. Grain output was relatively stable except for 2003. with the cold spots of grain production being mainly in the northwestern area and the hot spots in the central and southern areas. (2) The changes in grain production in North China from 2000 to 2020 were less affected by climate and mainly influenced by human activity indicators. (3) As time progresses, the area of food shortage zones decreases in size, becoming evenly distributed and dispersed from the initial concentration in northern Hebei and most of Shanxi; the change in the supply-demand equilibrium zones is not obvious; and the area of surplus grain zones increases markedly in size, with a tendency to expand from the south and centre of the study area to the west and north. The grain production capacity of counties in the northwest and north is generally low, and even counties located in surplus grain areas have potential food security risks. However, in the east and south, due to their high grain production capacity, the per capita grain supply situation may be alleviated even in counties located in grain shortage areas. This study can deepen the understanding of the characteristics of food production in North China and enrich the research on food security. Analyses of factors influencing food production will improve a deeper understanding of food security. Food security evaluation based on food production capacity will contribute to a more precise and comprehensive understanding of the food security pattern in North China.

Dopamine-based selective spectrophotometry p-aminosalicylic acid assay by hydrolyzate-triggered formation of azamonardine-like products.

BACKGROUND: The selective recognition of drugs and its metabolism or decomposition products is significant to drug development and drug resistance research. Fluorescence-based techniques provide satisfying sensitivity by target-triggered chemical reaction. However, the interference from the matrix or additives usually restricts the specific detection. It is highly desirable to explore specific chemical reactions for achieving selective perception of these species. RESULTS: We report a specific m-aminophenol (MAP)-dopamine (DA) reaction, which generates highly fluorescent azamonardine-like products. Based on this reaction, fluorometric and indirect detection of p-aminosalicylic acid (typical antituberculosis drug, PAS) can be realized using the DA-based probe with high sensitivity. The acid induces the decarboxylation of PAS and produces MAP, which reacts with DA and generates fluorescent azamonardine-like products. The practical application of the proposed method is validated by the accurate PAS analysis in urine samples and Pasinazid tablets. Interestingly, none of additives in the Pasinazid tablets contribute comparable fluorescence variation. SIGNIFICANCE: This work discovers a new MAP-DA reaction for the first time, it not only explores sensitive PAS drug detection probe, but also demonstrates the feasibility of the development of novel drug analysis platform by recognizing decomposition product with specific reaction. Thus, new avenues for the exploration of simple and rapid spectrophotometric probes toward various drug analytes with high specify and sensitivity based on this tactic might be possible in analytical and drug-related fields.

3,5-Dihydroxybenzoic Acid-Based Selective Dopamine Detection via Subsititution-Enhanced Kinetics Differences.

The selective recognition of dopamine (DA) over other neurotransmitter analogues is difficult due to the similar molecular structure and chemical reactivity. In this study, substitution-regulated chemical reactivity of the sensing substrate is utilized to explore a novel DA detection probe with satisfying selectivity. As a case study, 3,5-dihydroxybenzoic acid (DHBA, carboxy-substituted resorcinol)-based probes have been explored for selective and ratiometric DA sensing. The carboxy substitution benefits the stabilization of the carbanion intermediate and the azamonardine product, which enhances the reaction kinetics and thermodynamics and subsequently facilitates selective DA recognition over other analogues and interferents. By exploring DHBA emission as the internal reference, ratiometric fluorescence variation is realized, which contributes to sensitive DA analysis. With the combination of logic gate and fluorometric analysis, DA detection in both low and high concentrations can be readily achieved. In addition, the DA analysis in biological samples and the enzymatic transformation of DA analogues in cerebrospinal fluid samples are achieved by the proposed DHBA probe.

Herbicide Resistance: Another Hot Agronomic Trait for Plant Genome Editing.

Weeds have continually interrupted crop plants since their domestication, leading to a greater yield loss compared to diseases and pests that necessitated the practice of weed control measures. The control of weeds is crucial to ensuring the availability of sufficient food for a rapidly increasing human population. Chemical weed control (herbicides) along with integrated weed management (IWM) practices can be the most effective and reliable method of weed management programs. The application of herbicides for weed control practices calls for the urgency to develop herbicide-resistant (HR) crops. Recently, genome editing tools, especially CRISPR-Cas9, have brought innovation in genome editing technology that opens up new possibilities to provide sustainable farming in modern agricultural industry. To date, several non-genetically modified (GM) HR crops have been developed through genome editing that can present a leading role to combat weed problems along with increasing crop productivity to meet increasing food demand around the world. Here, we present the chemical method of weed control, approaches for herbicide resistance development, and possible advantages and limitations of genome editing in herbicide resistance. We also discuss how genome editing would be effective in combating intensive weed problems and what would be the impact of genome-edited HR crops in agriculture.

Regulating Fe-spin state by atomically dispersed Mn-N in Fe-N-C catalysts with high oxygen reduction activity.

As low-cost electrocatalysts for oxygen reduction reaction applied to fuel cells and metal-air batteries, atomic-dispersed transition metal-nitrogen-carbon materials are emerging, but the genuine mechanism thereof is still arguable. Herein, by rational design and synthesis of dual-metal atomically dispersed Fe,Mn/N-C catalyst as model object, we unravel that the O2 reduction preferentially takes place on FeIII in the FeN4 /C system with intermediate spin state which possesses one eg electron (t2g4eg1) readily penetrating the antibonding π-orbital of oxygen. Both magnetic measurements and theoretical calculation reveal that the adjacent atomically dispersed Mn-N moieties can effectively activate the FeIII sites by both spin-state transition and electronic modulation, rendering the excellent ORR performances of Fe,Mn/N-C in both alkaline and acidic media (halfwave positionals are 0.928 V in 0.1 M KOH, and 0.804 V in 0.1 M HClO4), and good durability, which outperforms and has almost the same activity of commercial Pt/C, respectively. In addition, it presents a superior power density of 160.8 mW cm-2 and long-term durability in reversible zinc-air batteries. The work brings new insight into the oxygen reduction reaction process on the metal-nitrogen-carbon active sites, undoubtedly leading the exploration towards high effective low-cost non-precious catalysts.

Ultratrace Pb determination in seawater by solution-cathode glow discharge-atomic emission spectrometry coupled with hydride generation.

A novel method for the determination of ultratrace Pb in seawater by solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) coupled with hydride generation (HG) has been developed. In the SCGD process, the hollow Ti tube, which can introduce gas instead of a solid tungsten rod is used as a discharge anode and combined with hydride generator. HG technology can not only separate Pb from a seawater matrix and reduce the matrix interference on detection, but can also significantly improve the transfer and atomization efficiencies for SCGD-AES. The optimum working conditions for HG and SCGD-AES for quantitative analysis of Pb were determined as 1% H2C2O4 as the masking agent and addition of 3% formic acid to increase Pb volatilization. The limit of detection (LOD) for Pb was decreased by two orders of magnitude in comparison to the SCGD-AES process alone. Under optimal conditions, the LOD for Pb was 0.17 µg L-1, and the relative standard deviation was 2.1% (n = 11) for 100 µg L-1 Pb in artificial seawater. The proposed quantification method was verified using a seawater reference material (BWQ7001-2016), and the obtained results agreed well with certified values. Finally, the approach was used to quantitatively analyse Pb in seawater, and the results agreed well with those obtained by inductively coupled plasma mass spectrometry. The recoveries of standard addition were between 96.0% and 103.0%.

Distribution and sources of organochlorine pesticides in agricultural soils from central China.

There is little information on the organochlorine pesticides (OCPs) residues in agricultural soils of Wuhan, the largest city in central China. Surface soil samples were collected from agricultural soils in Wuhan and analyzed to determine twenty-one OCPs. According to the measured concentrations and detection frequencies, dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), heptachlor (HEPT), hexachlorobenzene (HCB) and aldrin were the predominant compounds in soil. DDTs accounted for 77.10% of total OCPs, followed by HCHs (7.83%), aldrin (4.21%), HEPTs (2.82%) and HCB (1.53%). The total DDT concentrations ranged from nd to 1198.0ngg(-1) and the main contaminated areas were distributed in Hannan and Xinzhou districts of Wuhan. The total HCH concentrations ranged from nd to 100.58ngg(-1) in soil and relatively higher levels were observed in soil samples from Huangpi and Hannan districts. Source analysis showed that OCPs residues except heptachlor originated mainly from historical application, besides slight recent introduction at some sites. Based on the China National Soil Quality Standard, DDT pollution in most samples of Wuhan agricultural soils could be considered as no and low contamination, while the level of HCHs was classified as no pollution. Our study indicated that there existed potential exposure risk of OCPs in Wuhan agricultural soils although the use of OCPs has been banned.

[Cytological comparison of anther and pollen growth in Liriope spicata var. prolifera and L. spicata].

OBJECTIVE: To compare the difference of anther and pollen growth between Liriope spicata var. prolifera and L. spicate, and investigate the mechanism of the sterility of Liriope spicata var. prolifera. METHODS: A comparative study on anther and pollen growth process was carried out between L. spicata var. prolifera and L. spicata by means of paraffin section. RESULTS: In L. spicata, the tapetum was secretory tapetum and began to degrade during dyad stage. The cells of tapetum and middle layer disappeared thoroughly when pollens were fully mature at 3-celled stage. In L. spicata var. prolifera, the degradation of the tapetum took place at the early time of meiosis stage and the tapetum cells inflated like vacuolization. The mononuclear pollens were abortive, which eventually formed abnormal pollens. CONCLUSION: The pollen abortion of L. spicata var. prolifera is associated with tapetum heteroplasia and degradation in advance.