Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication,...Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication, and portable/wearable electronic equipment.In this work, a nacre-inspired multifunctional heterocyclic aramid(HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper withlarge-scale, high strength, super toughness, and excellent tolerance tocomplex conditions is fabricated through the strategy of HA/MXenehydrogel template-assisted in-situ assembly of PPy. Benefiting from the"brick-and-mortar" layered structure and the strong hydrogen-bondinginteractions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa),outstanding toughness (57.6 MJ m−3), exceptional foldability, and structural stability against ultrasonication. By using the template effect ofHA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly,the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dBat an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2g−1. In addition, the papers also have excellent applicationsin electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developinghigh-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management.展开更多
A strategy for the green synthesis of heterocyclicβ-ketosulfides via nucleophilic substitution ofα-halogenated ketone with het-eroaryl thiols in water media is presented.Compared with the available literature report...A strategy for the green synthesis of heterocyclicβ-ketosulfides via nucleophilic substitution ofα-halogenated ketone with het-eroaryl thiols in water media is presented.Compared with the available literature reports,this new method had the advantages of base-free,additives-free,simple operation,mild condition,greenness,high efficiency,tolerance of a broad scope of substrates.Furth-more,the reaction could easily be scaled up in gram scale and the products also could easily transformed to other useful organic compounds.Mechanism investigation indicated that the tautomerism of pyrimidine-2-thiol to pyrimidine-2(1H)-thione and the hy-drogen bonds played important roles in the reaction.展开更多
Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet dem...Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet demand and high cost.Nowadays,most quality control(QC)analysis of lemon oils is conducted by gas chromatography(GC)analysis,which is far from a reliable method.Oxygen heterocyclic compounds(OHCs)in non-volatile fraction are gaining increasing attention in authentication process because of the nearly finger-printing profiles of OHCs in cold pressed citrus essential oils.Our goal in this study was to identify OHCs using high performance liquid chromatography(HPLC)in lemon oils,establish OHC profiles,perform stepwise logistic regression analysis(SLRA)and build effective predicting model and further determine adulterated lemon oils by referencing the OHC profiles and established models.After HPLC analyses,profiling and SLRA modeling of 154 OHCs samples of industrial lemon oils,we found that the combination of isopimpinellin and total OHC concentration are essential and robust predictors to differentiate authentic samples from adulterated lemon oils with a success rate of 98%from the 5-fold cross validation.This study provided a reliable and efficient method in determining the authenticity of lemon oils.展开更多
The demand for anisotropic aerogels with excellent comprehensive properties in cutting-edge fields such as aerospace is growing.Based on the above background,a novel heterocyclic para-aramid nanofiber/reduced graphene...The demand for anisotropic aerogels with excellent comprehensive properties in cutting-edge fields such as aerospace is growing.Based on the above background,a novel heterocyclic para-aramid nanofiber/reduced graphene oxide(HPAN/rGO)composite aerogel was prepared by combining electrospinning and unidirectional freeze-drying.The anisotropic HPAN/rGO composite aerogel exhibited a honeycomb morphology in the direction perpendicular to the growth of ice crystals,and a through-well structure of directed microchannels in the direction parallel to the temperature gradient.By varying the mass ratio of HPAN/rGO,a composite aerogel with an ultra-low density of 5.34-7.81 mg·cm^(-3) and an ultra-high porosity of 98%-99%was obtained.Benefiting from the anisotropic structure,the radial and axial thermal conductivities of HPAN/rGO-3 composite aerogel were 29.37 and 44.35 mW·m^(-1)·K^(-1),respectively.A combination of software simulation and experiments was used to analyze the effect of anisotropic structures on the thermal insulation properties of aerogels.Moreover,due to the intrinsic self-extinguishing properties of heterocyclic para-aramid and the protection of the graphene carbon layer,the composite aerogel also exhibits excellent flame retardancy properties,and its total heat release rate(THR)was only 5.8 kJ·g^(-1),which is far superior to many reported aerogels.Therefore,ultralight anisotropic HPAN/rGO composite aerogels with excellent high-temperature thermal insulation and flame retardancy properties have broad application prospects in complex environments such as aerospace.展开更多
Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous...Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous explosive reactions when subjected to external stimuli such as electrical discharge.Therefore,developing a reliable model for predicting their electrostatic discharge sensitivity(ESD)becomes imperative.This study proposes a novel and straightforward model based on the presence of specific groups(-NH_(2) or-NH-,-N=N^(+)-O^(-)and-NNO_(2),-ONO_(2) or-NO_(2))under certain conditions to assess the ESD of NRHECs and their salts,employing interpretable structural parameters.Utilizing a comprehensive dataset comprising 54 ESD measurements of NRHECs and their salts,divided into 49/5 training/test sets,the model achieves promising results.The Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and Maximum Error for the training set are reported as 0.16 J,0.12 J,and 0.5 J,respectively.Notably,the ratios RMSE(training)/RMSE(test),MAE(training)/MAE(test),and Max Error(training)/Max Error(test)are all greater than 1.0,indicating the robust predictive capabilities of the model.The presented model demonstrates its efficacy in providing a reliable assessment of ESD for the targeted NRHECs and their salts,without the need for intricate computer codes or expert involvement.展开更多
The use of intramolecular reactions involving palladium/imidazolium salts to synthesize hetero-cyclic compounds is described. Reactivity of phenyl, ethyl and methyl substituents leading to isolation of various isomeri...The use of intramolecular reactions involving palladium/imidazolium salts to synthesize hetero-cyclic compounds is described. Reactivity of phenyl, ethyl and methyl substituents leading to isolation of various isomeric products is also illustrated. Rearrangement of phenyl intermediates to furnish benzoxazoles is also mentioned.展开更多
Plasmodium falciparum(P.falciparum) is responsible for the majority of life-threatening cases of human malaria,causing 1.5-2.7 million annual deaths.The global emergence of drug-resistant malaria parasites necessitate...Plasmodium falciparum(P.falciparum) is responsible for the majority of life-threatening cases of human malaria,causing 1.5-2.7 million annual deaths.The global emergence of drug-resistant malaria parasites necessitates identification and characterisation of novel drug targets and their potential inhibitors.We identified the carbonic anhydrase(CA) genes in P.falciparum.The pfGA gene encodes an α-carbonic anhydrase,a Zn^(2+)-metalloenzme,possessing catalytic properties distinct from that of the human host CA enzyme.The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes.A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions.The structure of the groups substituting the aromatic-ureido-or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides.One derivative,that is,4-(3,4-dichlorophenylureido)thioureidobcnzcnesulfonamide(compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor,and was also the most effective antimalarial compound on the in vitro P.falciparum growth inhibition.The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei,an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria.展开更多
Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe d...Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe diameter, initial pH and 03 dosage on the COD removal were studied. The results showed that the ultrasonic/O3 process significantly improved the biodegradability and reduced the biological toxicity of the wastewater. The ratio of BODs/COD was increased from 0.03 to 0.55 and the EC50 increased from 11% to 52% under ultrasonic/O3 treatment. Low ultrasonic frequency brought better COD removal. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable. The influences of ultrasonic power and probe diameter were small. With an increase in O3 dosage, COD removal was effectively improved. The optimal operational parameters for the combined process on COD removal were ultrasonic frequency 20 kHz, initial pH 9.00, ultrasonic power 300 W and dosage of O3 454.8 mg/（L.min）, under which the efficiency of COD removal reached 67.2%.展开更多
A new heterocyclic compound,named 5,5 -diisobutoxy-2,2 -bifuran(1),and four known compounds(2-5) were isolated from the roots of Cyathula officinalis Kuan.Their structures were elucidated by spectroscopic methods.Amon...A new heterocyclic compound,named 5,5 -diisobutoxy-2,2 -bifuran(1),and four known compounds(2-5) were isolated from the roots of Cyathula officinalis Kuan.Their structures were elucidated by spectroscopic methods.Among these compounds,5,5 - dibutoxy-2,2 -bifuran(2) was isolated for the first time from this plant.展开更多
Neodymium-based heterocyclic Schiff base complex was prepared and applied for the coordination polymerization of isoprene. This complex polymerized isoprene to afford products featuring high cis-1,4 stereospecificity ...Neodymium-based heterocyclic Schiff base complex was prepared and applied for the coordination polymerization of isoprene. This complex polymerized isoprene to afford products featuring high cis-1,4 stereospecificity （ca. 95%） and high molecular weight （ca, 10^5） in the presence of the triisobutyl aluminium （AliBu3） as cocatalyst, The microstructure of obtained polyisoprene was investigated by FTIR, 1^H NMR. Two different kinds of active centers in the catalyst system were examined by GPC method.展开更多
Semi-empirical molecular orbital calculations were performed on heterocyclic aromatic amines(HCAs). The relationship between the structures and the carcinogenicities can be rationally elucidated by the models based on...Semi-empirical molecular orbital calculations were performed on heterocyclic aromatic amines(HCAs). The relationship between the structures and the carcinogenicities can be rationally elucidated by the models based on the metabolism of HCAs and the Di-region theory. The degree of easiness for the formation of Di-region electrophilic centers determines the carcinogenic activity. There is a good linear relationship between the observed carcinogenicities and the PM3 calculated parameters, with r=0.973 and F=29.8>F ** 0.01 .展开更多
Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reacti...Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reaction of benzamide by directed lithiation and sequential treatment with sulfur and phosgene as key steps. All new compounds have been fully characterized by means of IR, ^1H NMR, ^13C NMR, and HRMS.展开更多
A series of new chelating resins with incorporating heterocyclic functional groups： pyridine, thiadizole, benzothizole into macroporous chloromethylated polystyrene were synthesized via hydrophilic spacer arm of poly...A series of new chelating resins with incorporating heterocyclic functional groups： pyridine, thiadizole, benzothizole into macroporous chloromethylated polystyrene were synthesized via hydrophilic spacer arm of polyethylene glycol containing sulfur. These chelating resins were found to show high adsorption capacities for Ag^＋, Hg^2＋, Au^3＋ and Pd^2＋, and the presence of spacer arm can enhance adsorption ability due to increase the hydrophilicity of the chelating resins.展开更多
Two heterocyclic Schiff bases were synthesized via the condensation reactions of primary amines with carbonyl compounds. 2-[（4-pyridylmethylene）-amino] phenol （compound 1） was synthesized by the interaction of 4-p...Two heterocyclic Schiff bases were synthesized via the condensation reactions of primary amines with carbonyl compounds. 2-[（4-pyridylmethylene）-amino] phenol （compound 1） was synthesized by the interaction of 4-pyridinecarboxaldehyde with o-aminophenol in ethanol solvent; N,N＇-bis（3-（furan-2-yl）allylidene）benzene-1,4-diamin （compound 2） was synthesized by the interaction of 3-（2-furyl）acrolein with p-phenylenediamine in ethanol medium. The compounds were characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction. Compound 1 （C12H10N2O） crystallizes in the monoclinic system, space group P21/c with α = 7.0771（7）, b = 7.2820（7）, c = 19.849（2）, b = 96.3390（10）°, V = 1016.66（17） ？3, Z = 4, Mr = 198.22, Dc = 1.295 g/cm3, F（000） = 416, GOOF = 1.060, m = 0.085 mm-1, the final R = 0.0371 and wR = 0.0929 for 1497 observed reflections with I 〉 2σ（I）. Compound 2 （C20H16N2O2） crystallizes in the orthorhombic system, space group Fdd2 with α = 26.344（15）, b = 48.50（3）, c = 5.293（3）, V = 6764（7） ？3, Z = 16, Mr = 316.35, Dc = 1.243 g/cm3, F（000） = 2656, GOOF = 1.043, m = 0.081 mm-1, the final R = 0.0526 and wR = 0.1267 for 2059 observed reflections with I 〉 2σ（I）. 1 and 2 molecules are connected through hydrogen bonds to generate a 2D network and a 1D chain structure, respectively. The preliminary antibacterial activity results showed that the title compounds display excellent antibacterial activities to Escherichia coli, Staphylococcus aureus and Bacillus subtilis.展开更多
Heterocyclic ketene aminals 1 react with aryl azides 2 to give the titled compounds 3,and in some cases also with the formation of fused heterocycles 4.
Meat products are an important part in our daily diet,providing valuable nutrients for the human body.However,heating processes cause the meat to become more appetizing with changes in texture,appearance,flavor,and ch...Meat products are an important part in our daily diet,providing valuable nutrients for the human body.However,heating processes cause the meat to become more appetizing with changes in texture,appearance,flavor,and chemical properties by the altering of protein structure and other ingredients.As one kind of cooking-induced contaminants,heterocyclic aromatic amines(HAAs)are widely present in protein aceous food products with strong carcinogenic and mutagenic properties.In order to promote the safety of traditional meat products,this review focused on the formation,metabolism,biological monitoring and inhibitory mechanism of HAA.An overview of the formation pathways,hazards,and control methods of HAAs during food processing in recent years was studied,aiming to provide some valuable information for exploring effective methods to inhibit the production of associated hazards during food processing.Systematic selection of different types of flavonoids to explore their effects on the formation of HAAs in an actual barbecue system can provide theoretical reference for effectively controlling the formation of HAAs and reducing their harm to human health.展开更多
The aim of the present study was to compare the ability of the myricetin and quercetin to modulate the oxidative DNA damage induced by 2-amino-3, 8- dimethylimidazo [4,5-f] quinoxaline (8-MeIQx), 2-amino- 3, 4, 8- tri...The aim of the present study was to compare the ability of the myricetin and quercetin to modulate the oxidative DNA damage induced by 2-amino-3, 8- dimethylimidazo [4,5-f] quinoxaline (8-MeIQx), 2-amino- 3, 4, 8- trimethylimidazo [4, 5-f]-quinoxaline (4,8-diMeIQx) and 2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (PhIP), in human hepatoma cells. DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. None of the myricetin and quercetin concentrations tested protected against 8-MeIQx, 4, 8-diMeIQx and PhIP-induced DNA strand breaks. The oxidized pyrimidines induced by 4, 8-diMeIQx and PhIP were reduced by myricetin but not by quercetin. Quercetin reduced the oxidized purines induced by 8-MeIQx and PhIP, while myricetin also reduced the induced by 4, 8-diMeIQx. One feasible mechanism by which myricetin and quercetin exert their protective effect towards HCAs-induced oxidative DNA could be related in part to the reduction of human CYP1A1. Another mechanism claimed to be responsible for the protective effect of myricetin and quercetin is the induction of phase II metabolizing enzymes such as UDP-glucuronyltrasferase (UGT). The ethoxyresorufin O-deethylation (CYP1A1) activity was moderately inhibited by myricetin, while little effect was observed by quercetin. On the contrary, quercetin showed the greatest increase on UDP-glucuronyltransferase activity. However, these are not the only mechanisms by which myricetin and quercetin exert their protective effect, other mechanisms such as stimulation of the repair of carcinogen-induced DNA damage and or the free radical scavenging efficiency have been also implicated. In conclusion, our results clearly indicate that myricetin was more efficient than quercetin to prevent DNA damage (oxidized purines and pyrimidines) induced by the three HCAs evaluated. This protective effect depends on the chemical structure of flavonoid and the mutagen studied.展开更多
Recent investigations have shown the oxone-mediated oxidative methyl esterification of benzaldehyde derivatives using methanol. The reactions were accelerated in the presence of indium(III) triflate, a trivalent indiu...Recent investigations have shown the oxone-mediated oxidative methyl esterification of benzaldehyde derivatives using methanol. The reactions were accelerated in the presence of indium(III) triflate, a trivalent indium reagent, in many cases. Based on this method of methyl esterification of benzaldehyde derivatives, we further explored an application to heterocyclic aldehydes. The reactions were examined using methanol as well as other alcohols in order to establish a suitable range.展开更多
Dihydro-1H-1, 5-benzodiazepines and 1-benzoy1-2, 3-dihydro-1H-1H-1,5-benzodiazepines react with .α-carbonylkelenes, generated from 2-diazo-1,3-diphenyl-1,3-propandione or 2-diazo-1-phenyl-1,3-butandione by heating, t...Dihydro-1H-1, 5-benzodiazepines and 1-benzoy1-2, 3-dihydro-1H-1H-1,5-benzodiazepines react with .α-carbonylkelenes, generated from 2-diazo-1,3-diphenyl-1,3-propandione or 2-diazo-1-phenyl-1,3-butandione by heating, to give 4a,5, 6, 12-letralydro- 1H,7H-1,3-oxazino[3,2-d][1,5]-benzodiazepine-1-ones,a new ring system. 2, 3-Dihydro-1H-1,5-benzodiazepines also afford,dducts of H-N bond,with a carbonylketenes, 2-aryt-1-(2-benzoyl-phenylacelyl)-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepines. Addition of henzonitrile N-phenylimine,yielde in situ from the N-phenyl benzenecarbohydrazic chloride,to 2, 4-diaryl-2, 3-dihydro-1,5-benzothiazepines and 1H-1,5-benzodiazepine gave 3a, 5-diaryl-1, 3-diphenyl-3a, 4, 5, 11 tetralydro-3H-1, 2, 4-triazolo [4, 3-d][1. 5]benzothiazepine and 3H,6H-1, 2, 4 triazolo[4, 3-d][1, 5] benzodiazpine, respectively.展开更多
Diamide compounds such as chlorantraniliprole,a famous anthranilic diamide insecticide targeting the insect ryanodine receptor(Ry R),have received continuous attention in pesticide research during the past 15 years ow...Diamide compounds such as chlorantraniliprole,a famous anthranilic diamide insecticide targeting the insect ryanodine receptor(Ry R),have received continuous attention in pesticide research during the past 15 years owing to their excellent insecticidal potentials.With the aim of discovering new heterocyclic pesticides used for crop protection,based on the structural information of compound M from the reported pharmacophore-based virtual screening for Ry R insecticides and diamide compound,a series of new heterocyclic mono-,di-,and tri-amide derivatives containing piperazine moiety have been synthesized in this paper.The new compounds were identified and confirmed by melting point,^(1)H NMR,^(13)C NMR and HRMS.Compound M was firstly validated for insecticidal activities,and the new synthesized compounds were all made comprehensive insecticidal evaluations against diamondback moth and oriental armyworm.The bioassay results showed that some of the compounds exhibit favorable insecticidal potentials,particularly some novel piperazine-containing heterocyclic mono-/di-/tri-amide derivatives such as 8 g,14 a,15 a,15 g,15 i,15 j,15 k,15 l,and 15 m could be used as new insecticidal leading structures for further study(e.g.,towards diamondback moth,15i-15 m LC_(50):0.0022-0.0081 mg/L).The structure-activity relationships of the compounds discussed in detail provide useful guidance for further design and development of new insecticides.展开更多
基金supported by the Fundamental Research Funds for the Central Universities and Heilongjiang Provincial Natural Science Foundation of China(Grant No.YQ2020E009).
文摘Robust, ultra-flexible, and multifunctional MXene-basedelectromagnetic interference (EMI) shielding nanocomposite filmsexhibit enormous potential for applications in artificial intelligence,wireless telecommunication, and portable/wearable electronic equipment.In this work, a nacre-inspired multifunctional heterocyclic aramid(HA)/MXene@polypyrrole (PPy) (HMP) nanocomposite paper withlarge-scale, high strength, super toughness, and excellent tolerance tocomplex conditions is fabricated through the strategy of HA/MXenehydrogel template-assisted in-situ assembly of PPy. Benefiting from the"brick-and-mortar" layered structure and the strong hydrogen-bondinginteractions among MXene, HA, and PPy, the paper exhibits remarkable mechanical performances, including high tensile strength (309.7 MPa),outstanding toughness (57.6 MJ m−3), exceptional foldability, and structural stability against ultrasonication. By using the template effect ofHA/MXene to guide the assembly of conductive polymers, the synthesized paper obtains excellent electronic conductivity. More importantly,the highly continuous conductive path enables the nanocomposite paper to achieve a splendid EMI shielding effectiveness (EMI SE) of 54.1 dBat an ultra-thin thickness (25.4 μm) and a high specific EMI SE of 17,204.7 dB cm2g−1. In addition, the papers also have excellent applicationsin electromagnetic protection, electro-/photothermal de-icing, thermal therapy, and fire safety. These findings broaden the ideas for developinghigh-performance and multifunctional MXene-based films with enormous application potential in EMI shielding and thermal management.
文摘A strategy for the green synthesis of heterocyclicβ-ketosulfides via nucleophilic substitution ofα-halogenated ketone with het-eroaryl thiols in water media is presented.Compared with the available literature reports,this new method had the advantages of base-free,additives-free,simple operation,mild condition,greenness,high efficiency,tolerance of a broad scope of substrates.Furth-more,the reaction could easily be scaled up in gram scale and the products also could easily transformed to other useful organic compounds.Mechanism investigation indicated that the tautomerism of pyrimidine-2-thiol to pyrimidine-2(1H)-thione and the hy-drogen bonds played important roles in the reaction.
文摘Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet demand and high cost.Nowadays,most quality control(QC)analysis of lemon oils is conducted by gas chromatography(GC)analysis,which is far from a reliable method.Oxygen heterocyclic compounds(OHCs)in non-volatile fraction are gaining increasing attention in authentication process because of the nearly finger-printing profiles of OHCs in cold pressed citrus essential oils.Our goal in this study was to identify OHCs using high performance liquid chromatography(HPLC)in lemon oils,establish OHC profiles,perform stepwise logistic regression analysis(SLRA)and build effective predicting model and further determine adulterated lemon oils by referencing the OHC profiles and established models.After HPLC analyses,profiling and SLRA modeling of 154 OHCs samples of industrial lemon oils,we found that the combination of isopimpinellin and total OHC concentration are essential and robust predictors to differentiate authentic samples from adulterated lemon oils with a success rate of 98%from the 5-fold cross validation.This study provided a reliable and efficient method in determining the authenticity of lemon oils.
基金supported by the National Key R&D Program of China(No.2021YFB3700103).
文摘The demand for anisotropic aerogels with excellent comprehensive properties in cutting-edge fields such as aerospace is growing.Based on the above background,a novel heterocyclic para-aramid nanofiber/reduced graphene oxide(HPAN/rGO)composite aerogel was prepared by combining electrospinning and unidirectional freeze-drying.The anisotropic HPAN/rGO composite aerogel exhibited a honeycomb morphology in the direction perpendicular to the growth of ice crystals,and a through-well structure of directed microchannels in the direction parallel to the temperature gradient.By varying the mass ratio of HPAN/rGO,a composite aerogel with an ultra-low density of 5.34-7.81 mg·cm^(-3) and an ultra-high porosity of 98%-99%was obtained.Benefiting from the anisotropic structure,the radial and axial thermal conductivities of HPAN/rGO-3 composite aerogel were 29.37 and 44.35 mW·m^(-1)·K^(-1),respectively.A combination of software simulation and experiments was used to analyze the effect of anisotropic structures on the thermal insulation properties of aerogels.Moreover,due to the intrinsic self-extinguishing properties of heterocyclic para-aramid and the protection of the graphene carbon layer,the composite aerogel also exhibits excellent flame retardancy properties,and its total heat release rate(THR)was only 5.8 kJ·g^(-1),which is far superior to many reported aerogels.Therefore,ultralight anisotropic HPAN/rGO composite aerogels with excellent high-temperature thermal insulation and flame retardancy properties have broad application prospects in complex environments such as aerospace.
文摘Nitrogen-rich heterocyclic energetic compounds(NRHECs)and their salts have witnessed widespread synthesis in recent years.The substantial energy-density content within these compounds can lead to potentially dangerous explosive reactions when subjected to external stimuli such as electrical discharge.Therefore,developing a reliable model for predicting their electrostatic discharge sensitivity(ESD)becomes imperative.This study proposes a novel and straightforward model based on the presence of specific groups(-NH_(2) or-NH-,-N=N^(+)-O^(-)and-NNO_(2),-ONO_(2) or-NO_(2))under certain conditions to assess the ESD of NRHECs and their salts,employing interpretable structural parameters.Utilizing a comprehensive dataset comprising 54 ESD measurements of NRHECs and their salts,divided into 49/5 training/test sets,the model achieves promising results.The Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and Maximum Error for the training set are reported as 0.16 J,0.12 J,and 0.5 J,respectively.Notably,the ratios RMSE(training)/RMSE(test),MAE(training)/MAE(test),and Max Error(training)/Max Error(test)are all greater than 1.0,indicating the robust predictive capabilities of the model.The presented model demonstrates its efficacy in providing a reliable assessment of ESD for the targeted NRHECs and their salts,without the need for intricate computer codes or expert involvement.
文摘The use of intramolecular reactions involving palladium/imidazolium salts to synthesize hetero-cyclic compounds is described. Reactivity of phenyl, ethyl and methyl substituents leading to isolation of various isomeric products is also illustrated. Rearrangement of phenyl intermediates to furnish benzoxazoles is also mentioned.
基金Supported by a grant from UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases(No.900142,930143,960103,970074,990490)the National Science and Technology Development Agency of Thailand(Career Development Award ID no.01-38-007)the Thailand Research Fund(BasicResearch Grants ID No.BRG/13/2543.BRG4580020.BRG 4880006)
文摘Plasmodium falciparum(P.falciparum) is responsible for the majority of life-threatening cases of human malaria,causing 1.5-2.7 million annual deaths.The global emergence of drug-resistant malaria parasites necessitates identification and characterisation of novel drug targets and their potential inhibitors.We identified the carbonic anhydrase(CA) genes in P.falciparum.The pfGA gene encodes an α-carbonic anhydrase,a Zn^(2+)-metalloenzme,possessing catalytic properties distinct from that of the human host CA enzyme.The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes.A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions.The structure of the groups substituting the aromatic-ureido-or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides.One derivative,that is,4-(3,4-dichlorophenylureido)thioureidobcnzcnesulfonamide(compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor,and was also the most effective antimalarial compound on the in vitro P.falciparum growth inhibition.The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei,an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria.
基金supported by the National Water Pollution Control and Management Technology Major Project(No. 2008ZX07316-003)
文摘Ultrasonic/O3 combined process was employed to pretreat heterocyclic pesticide wastewater for increasing biodegradability and reducing biological toxicity. Influences of ultrasonic frequency, ultrasonic power, probe diameter, initial pH and 03 dosage on the COD removal were studied. The results showed that the ultrasonic/O3 process significantly improved the biodegradability and reduced the biological toxicity of the wastewater. The ratio of BODs/COD was increased from 0.03 to 0.55 and the EC50 increased from 11% to 52% under ultrasonic/O3 treatment. Low ultrasonic frequency brought better COD removal. Initial pH was found to have a high influence on the COD removal and alkaline conditions were more favorable. The influences of ultrasonic power and probe diameter were small. With an increase in O3 dosage, COD removal was effectively improved. The optimal operational parameters for the combined process on COD removal were ultrasonic frequency 20 kHz, initial pH 9.00, ultrasonic power 300 W and dosage of O3 454.8 mg/（L.min）, under which the efficiency of COD removal reached 67.2%.
基金the Natural Science Foundation of Tianjin(No.06YFJMJC15800) for the financial support.
文摘A new heterocyclic compound,named 5,5 -diisobutoxy-2,2 -bifuran(1),and four known compounds(2-5) were isolated from the roots of Cyathula officinalis Kuan.Their structures were elucidated by spectroscopic methods.Among these compounds,5,5 - dibutoxy-2,2 -bifuran(2) was isolated for the first time from this plant.
基金The authors are indebted to the financial supports of the National Natural Science Foundation of China （No.20774078 and the Key Program No.20434020）；the Special Funds for Major Basic Research Projects （G2005CB623802）.
文摘Neodymium-based heterocyclic Schiff base complex was prepared and applied for the coordination polymerization of isoprene. This complex polymerized isoprene to afford products featuring high cis-1,4 stereospecificity （ca. 95%） and high molecular weight （ca, 10^5） in the presence of the triisobutyl aluminium （AliBu3） as cocatalyst, The microstructure of obtained polyisoprene was investigated by FTIR, 1^H NMR. Two different kinds of active centers in the catalyst system were examined by GPC method.
基金the National Natural Science Foundation of China(No.2 0 0 4 2 0 0 1) and by the Postdoctoral Foundation ofthe Ministry of Education P.R.China
文摘Semi-empirical molecular orbital calculations were performed on heterocyclic aromatic amines(HCAs). The relationship between the structures and the carcinogenicities can be rationally elucidated by the models based on the metabolism of HCAs and the Di-region theory. The degree of easiness for the formation of Di-region electrophilic centers determines the carcinogenic activity. There is a good linear relationship between the observed carcinogenicities and the PM3 calculated parameters, with r=0.973 and F=29.8>F ** 0.01 .
基金financially supported by the Scientific Research Foundation of Northwest University(No. PR10035)
文摘Facile synthesis of the two new natural heterocyclic compounds bretschneiderazines A （2） and B （3）, isolated from an extract of the stems of Bretschneidera sinensis, is reported. We employed the cyclization reaction of benzamide by directed lithiation and sequential treatment with sulfur and phosgene as key steps. All new compounds have been fully characterized by means of IR, ^1H NMR, ^13C NMR, and HRMS.
基金The authors are grateful to the financial support by the Postdoctoral Science Foundation of China(No.2003034330)the Science Foundation for mid-youth elite of Shangdong Province+1 种基金the Natural Science Foundation of Shangdong Province(No.Q99B15)the National Natural Science Foundation of China(No.2906008)
文摘A series of new chelating resins with incorporating heterocyclic functional groups： pyridine, thiadizole, benzothizole into macroporous chloromethylated polystyrene were synthesized via hydrophilic spacer arm of polyethylene glycol containing sulfur. These chelating resins were found to show high adsorption capacities for Ag^＋, Hg^2＋, Au^3＋ and Pd^2＋, and the presence of spacer arm can enhance adsorption ability due to increase the hydrophilicity of the chelating resins.
基金Supported by the Natural Science Foundation of China(No.21264011,20961007)
文摘Two heterocyclic Schiff bases were synthesized via the condensation reactions of primary amines with carbonyl compounds. 2-[（4-pyridylmethylene）-amino] phenol （compound 1） was synthesized by the interaction of 4-pyridinecarboxaldehyde with o-aminophenol in ethanol solvent; N,N＇-bis（3-（furan-2-yl）allylidene）benzene-1,4-diamin （compound 2） was synthesized by the interaction of 3-（2-furyl）acrolein with p-phenylenediamine in ethanol medium. The compounds were characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction. Compound 1 （C12H10N2O） crystallizes in the monoclinic system, space group P21/c with α = 7.0771（7）, b = 7.2820（7）, c = 19.849（2）, b = 96.3390（10）°, V = 1016.66（17） ？3, Z = 4, Mr = 198.22, Dc = 1.295 g/cm3, F（000） = 416, GOOF = 1.060, m = 0.085 mm-1, the final R = 0.0371 and wR = 0.0929 for 1497 observed reflections with I 〉 2σ（I）. Compound 2 （C20H16N2O2） crystallizes in the orthorhombic system, space group Fdd2 with α = 26.344（15）, b = 48.50（3）, c = 5.293（3）, V = 6764（7） ？3, Z = 16, Mr = 316.35, Dc = 1.243 g/cm3, F（000） = 2656, GOOF = 1.043, m = 0.081 mm-1, the final R = 0.0526 and wR = 0.1267 for 2059 observed reflections with I 〉 2σ（I）. 1 and 2 molecules are connected through hydrogen bonds to generate a 2D network and a 1D chain structure, respectively. The preliminary antibacterial activity results showed that the title compounds display excellent antibacterial activities to Escherichia coli, Staphylococcus aureus and Bacillus subtilis.
文摘Heterocyclic ketene aminals 1 react with aryl azides 2 to give the titled compounds 3,and in some cases also with the formation of fused heterocycles 4.
基金supported by National Postdoctoral Program(2020M682073)the National Natural Science Foundation of China(NSFC,32061160477)+1 种基金The National Natural Science Foundation of China(32272315,32072209)the Natural Science Foundation of Guangdong Province(2022A1515010694).
文摘Meat products are an important part in our daily diet,providing valuable nutrients for the human body.However,heating processes cause the meat to become more appetizing with changes in texture,appearance,flavor,and chemical properties by the altering of protein structure and other ingredients.As one kind of cooking-induced contaminants,heterocyclic aromatic amines(HAAs)are widely present in protein aceous food products with strong carcinogenic and mutagenic properties.In order to promote the safety of traditional meat products,this review focused on the formation,metabolism,biological monitoring and inhibitory mechanism of HAA.An overview of the formation pathways,hazards,and control methods of HAAs during food processing in recent years was studied,aiming to provide some valuable information for exploring effective methods to inhibit the production of associated hazards during food processing.Systematic selection of different types of flavonoids to explore their effects on the formation of HAAs in an actual barbecue system can provide theoretical reference for effectively controlling the formation of HAAs and reducing their harm to human health.
文摘The aim of the present study was to compare the ability of the myricetin and quercetin to modulate the oxidative DNA damage induced by 2-amino-3, 8- dimethylimidazo [4,5-f] quinoxaline (8-MeIQx), 2-amino- 3, 4, 8- trimethylimidazo [4, 5-f]-quinoxaline (4,8-diMeIQx) and 2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (PhIP), in human hepatoma cells. DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. None of the myricetin and quercetin concentrations tested protected against 8-MeIQx, 4, 8-diMeIQx and PhIP-induced DNA strand breaks. The oxidized pyrimidines induced by 4, 8-diMeIQx and PhIP were reduced by myricetin but not by quercetin. Quercetin reduced the oxidized purines induced by 8-MeIQx and PhIP, while myricetin also reduced the induced by 4, 8-diMeIQx. One feasible mechanism by which myricetin and quercetin exert their protective effect towards HCAs-induced oxidative DNA could be related in part to the reduction of human CYP1A1. Another mechanism claimed to be responsible for the protective effect of myricetin and quercetin is the induction of phase II metabolizing enzymes such as UDP-glucuronyltrasferase (UGT). The ethoxyresorufin O-deethylation (CYP1A1) activity was moderately inhibited by myricetin, while little effect was observed by quercetin. On the contrary, quercetin showed the greatest increase on UDP-glucuronyltransferase activity. However, these are not the only mechanisms by which myricetin and quercetin exert their protective effect, other mechanisms such as stimulation of the repair of carcinogen-induced DNA damage and or the free radical scavenging efficiency have been also implicated. In conclusion, our results clearly indicate that myricetin was more efficient than quercetin to prevent DNA damage (oxidized purines and pyrimidines) induced by the three HCAs evaluated. This protective effect depends on the chemical structure of flavonoid and the mutagen studied.
文摘Recent investigations have shown the oxone-mediated oxidative methyl esterification of benzaldehyde derivatives using methanol. The reactions were accelerated in the presence of indium(III) triflate, a trivalent indium reagent, in many cases. Based on this method of methyl esterification of benzaldehyde derivatives, we further explored an application to heterocyclic aldehydes. The reactions were examined using methanol as well as other alcohols in order to establish a suitable range.
文摘Dihydro-1H-1, 5-benzodiazepines and 1-benzoy1-2, 3-dihydro-1H-1H-1,5-benzodiazepines react with .α-carbonylkelenes, generated from 2-diazo-1,3-diphenyl-1,3-propandione or 2-diazo-1-phenyl-1,3-butandione by heating, to give 4a,5, 6, 12-letralydro- 1H,7H-1,3-oxazino[3,2-d][1,5]-benzodiazepine-1-ones,a new ring system. 2, 3-Dihydro-1H-1,5-benzodiazepines also afford,dducts of H-N bond,with a carbonylketenes, 2-aryt-1-(2-benzoyl-phenylacelyl)-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepines. Addition of henzonitrile N-phenylimine,yielde in situ from the N-phenyl benzenecarbohydrazic chloride,to 2, 4-diaryl-2, 3-dihydro-1,5-benzothiazepines and 1H-1,5-benzodiazepine gave 3a, 5-diaryl-1, 3-diphenyl-3a, 4, 5, 11 tetralydro-3H-1, 2, 4-triazolo [4, 3-d][1. 5]benzothiazepine and 3H,6H-1, 2, 4 triazolo[4, 3-d][1, 5] benzodiazpine, respectively.
基金financially supported by the National Key Research and Development Program of China(No.2017YFD0200505)the National Natural Science Foundation of China(No.21772103)。
文摘Diamide compounds such as chlorantraniliprole,a famous anthranilic diamide insecticide targeting the insect ryanodine receptor(Ry R),have received continuous attention in pesticide research during the past 15 years owing to their excellent insecticidal potentials.With the aim of discovering new heterocyclic pesticides used for crop protection,based on the structural information of compound M from the reported pharmacophore-based virtual screening for Ry R insecticides and diamide compound,a series of new heterocyclic mono-,di-,and tri-amide derivatives containing piperazine moiety have been synthesized in this paper.The new compounds were identified and confirmed by melting point,^(1)H NMR,^(13)C NMR and HRMS.Compound M was firstly validated for insecticidal activities,and the new synthesized compounds were all made comprehensive insecticidal evaluations against diamondback moth and oriental armyworm.The bioassay results showed that some of the compounds exhibit favorable insecticidal potentials,particularly some novel piperazine-containing heterocyclic mono-/di-/tri-amide derivatives such as 8 g,14 a,15 a,15 g,15 i,15 j,15 k,15 l,and 15 m could be used as new insecticidal leading structures for further study(e.g.,towards diamondback moth,15i-15 m LC_(50):0.0022-0.0081 mg/L).The structure-activity relationships of the compounds discussed in detail provide useful guidance for further design and development of new insecticides.
