Chromium in soil detection using adaptive weighted normalization and linear weighted network framework for LIBS matrix effect reduction.

Rapid and accurate detection of agricultural soil chromium (Cr) is of great significance for soil pollution assessment. Laser-induced breakdown spectroscopy (LIBS) could serve as a rapid and chemical-free method for hazardous metal analysis compared with conventional chemical methods. However, the detection of LIBS is interfered by uncertainty and matrix effect. In this study, an average strategy combined with linear weighted network (LWNet) was proposed to reduce the uncertainty. Adaptive weighted normalization-LWNet (AWN-LWNet) framework was proposed to reduce the matrix effect in two soil types. The results indicated that LWNet outperformed traditional machine learning and achieved the average relative error (ARE) of 2.08 % and 3.03 % for yellow brown soil and lateritic red soil, respectively. Moreover, LWNet could effectively mine Cr feature peaks even under the low spectral resolution. AWN-LWNet was the optimal model compared with commonly used models to reduce matrix effect (ARE=4.12 %). Besides, AWN-LWNet greatly reduced the number (from 22016 to 72) of spectral variables for model input. By extracting Cr peaks from models, the difference of Cr peaks intensity could be intuitively observed, which served as spectral interpretation for matrix effect reduction. The two methods have the potential to realize the detection of hazardous metals in soil by LIBS.

Screening of a potential leafhopper attractants and their applications in tea plantations.

Pheromones can be used as leafhopper attractants. However, commercial pheromone products, such as the Ingle lure, have certain limitations, including poor persistence in the field. In this study, (E)-2-hexenal, (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, (E)-ocimene, linalool, and geraniol were selected and behaviorally tested as potential leafhopper attractants. Y-tube olfactometer tests showed that the C2 formulation was more effective than other formulations. In tea field trials, the number of leafhoppers caught by sticky board traps baited with C2 lures was greater than that caught by treatment. The number of leafhoppers attracted by the C2 lures was greater than that attracted by the commercial Ingle lures. Additionally, the total amount of active C2 components on lures was greater than that of the active components on the lure after 14 days. Thus, the results indicated that the C2 formulation may attract leafhoppers and have a greater persistence than other formulations in tea field.

Enantioselective degradation of indoxacarb from different commercial formulations applied to tea.

The stereoselective degradation of indoxacarb enriched with (+)-S-indoxacarb (S/R:70/30) was investigated in three typical green teas. A convenient and precise chiral method was developed and validated for measuring indoxacarb enantiomers in green tea. The developed method was based on high-performance liquid chromatography coupled with tandem mass spectrometry using a Chiralpak IC column. The stereoselective degradation of indoxacarb enantiomers showed that the (+)-S-enantiomer dissipated faster than the (-)-R-enantiomer in all three typical tea farms. However, no enantiomerization was observed after applying pure (+)-S-indoxacarb. Residues on tea plant of the active ingredient (+)-S-indoxacarb from suspension concentrate (SC) was more persistent than that from emulsifiable concentrate (EC).

Synthesis and antiviral bioactivity of novel 3-((2-((1E,4E)-3-oxo-5-arylpenta-1,4-dien-1-yl)phenoxy)methyl)-4(3H)-quinazolinone derivatives.

A series of novel 3-((2-((1E,4E)-3-oxo-5-arylpenta-1,4-dien-1-yl)phenoxy)methyl)-4(3H)-quinazolinone derivatives were designed and synthesized. Antiviral bioassays indicated that a few of the compounds exhibited higher antiviral activities against tobacco mosaic virus (TMV) in vivo than the commercial agent ningnanmycin. In particular, compounds A5, A12, A25, and A27 possessed appreciable curative bioactivities on TMV in vivo, with 50% effective concentration values ranging from 132.25 to 156.10 µg/mL. These values are superior to that of ningnanmycin (281.22 µg/mL) and suggest that novel 4(3H)-quinazolinone derivatives containing 1,4-pentadien-3-one moiety can effectively control TMV. Evaluation of the antiviral properties in field studies and the mechanisms underlying the enhanced antiviral activities of these derivatives are an interesting topic for future investigation.

Cinchona alkaloid derivative-catalyzed enantioselective synthesis via a Mannich-type reaction and antifungal activity of ß-amino esters bearing benzoheterocycle moieties.

An efficient synthesis of highly functionalized chiral ß-amino ester derivatives containing benzothiophene and benzothiazole moieties is developed by a Mannich-type reaction using a cinchona alkaloid-derived thiourea catalyst. The desired products were obtained in good yields and high enantioselectivities (~86% yield, >99% ee) using to the optimized reaction conditions. The synthesized compounds were characterized by 1H-NMR, 13C-NMR, IR, and HREI-MS analyses. The bioassays identified that compound 5dr has excellent antifungal activity, with a 60.53% inhibition rate against F. oxysporum, higher than that of the commercial agricultural fungicide hymexazol, whose inhibition rate was 56.12%.

Design, synthesis, and antibacterial activity against rice bacterial leaf blight and leaf streak of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivative.

A series of 2,5-substituted-1,3,4-oxadiazole/thiadiazole sulfone derivatives were synthesized and evaluated for their antibacterial activities against rice bacterial leaf blight and leaf streak caused by Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicolaby via the turbidimeter test in vitro. Antibacterial bioassay results indicated that most compounds demonstrated good inhibitory effect antibacterial bioactivities against rice bacterial leaf blight and leaf streak. Among the title compounds, compound 6c demonstrated the best inhibitory effect against rice bacterial leaf blight and leaf streak with half-maximal effective concentration (EC50) values of 1.07 and 7.14 µg/mL, respectively, which were even better than those of commercial agents such as Bismerthiazol and Thiediazole Copper. In vivo antibacterial activities tests at greenhouse conditions demonstrated that the controlling effect of compounds 6c (43.5%) and 6g (42.4%) against rice bacterial leaf blight were better than those of Bismerthiazol (25.5%) and Thiediazole Copper (37.5%).

Synthesis and antifungal activities of novel nicotinamide derivatives containing 1,3,4-oxadiazole.

BACKGROUND: Pant diseases in agriculture are extremely difficult to control, which bring about for billions of dollars in economic losses worldwide each year; Nicotinamide derivatives has attracted more and more attention in the field of pesticide due to their broad bioactivities. In an effort to discover new molecules with good antifungal activity, a series of nicotinamide derivatives containing 1,3,4-oxadiazole were synthesized and bio-assayed. RESULTS: Bioassays demonstrated that some of the title compounds exhibited favorable antifungal activities against Gibberella zeae, Fusarium oxysporum, and Cytospora mandshurica. compounds 7b, 7c, 8, 9a, 9b, and 9c displayed 46.4%, 39.6%, 53.0%, 43.2%, 58.3%, 45.6% activities against G. Zeae, respectively; the activities of compounds 7a, 7b, 8, 9a, 9b, and 9c against F. oxysporum were 55.2%, 51.1%, 58.9%, 63.2%, 53.3%, and 47.6%, respectively; whereas inhibitory rates of compounds 7a, 7b, 7c, 8, 9a, 9b, and 9c on C. mandshurica were 53.1%, 49.9%, 44.9%, 52.8%, 59.8%, 54.5%, and 49.3%, respectively. CONCLUSION: A series of the novel nicotinamide derivatives containing 1,3,4-oxadiazole were synthesized and bio-assayed. The results of antifungal tests revealed that the synthesized nicotinamide derivatives possessed weakly to moderately antifungal activities against G. zeae, F. oxysporum, and C. mandshurica. Most of the synthesized compounds exhibited similar activities as (or higher than) these of hymexozol on their corresponding fungus, and compounds 7a, 8, 9a, and 9b showed considerable prospects for further optimization. Primary structure-activity relationships revealed that the introduction of the groups of 4-chloro-6-methyl on benzene, the hydrazone group containing N,N-dimethylamino, and acetyl at -NH2 could enhance the antifungal activity.

N-substituted 5-chloro-6-phenylpyridazin-3(2H)-ones: synthesis, insecticidal activity against Plutella xylostella (L.) and SAR study.

A series of N-substituted 5-chloro-6-phenylpyridazin-3(2H)-one derivatives were synthesized based on our previous work; all compounds were characterized by spectral data and tested for in vitro insecticidal activity against Plutella xylostella. The results showed that the synthesized pyridazin-3(2H)-one compounds possessed good insecticidal activities, especially the compounds 4b, 4d, and 4h which showed > 90% activity at 100 mg/L. The structure-activity relationships (SAR) for these compounds were also discussed.