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•Mesoporous Metal-POM@MOF-199@MCM-41 was prepared for oxidative desulfurization.•The hybrid catalyst leads to the deep DBT conversion with O2 as oxidation.•Stability is mainly ...correlated with MOF-199 and MCM-41.•The oxidation of DBT followed pseudo-first-order kinetics.
A kind of composite catalytic materials, Metal-POM@MOF-199@MCM-41 (Metal-PMM), were obtained by confining MOF-199 encapsulating metallic Keggin POM into mesoporous MCM-41. The catalyst was designed on the stability and efficiency, which MCM-41 could act as a stable cavy for the heterogeneous metallic POM-based catalyst in the oxidative desulfurization process. The structure characteristics of the catalysts were elucidated through XRD, IR, XPS, N2 adsorption-desorption, SEM and TEM. The reaction rate could be greatly enhanced, up to 99.1%, under Co-PMM as catalyst and O2 as oxidant. After reaction, the catalyst can be simply recovered and reused more than 5 times without the change of its structure, for the strongly fixation of MOF-199 and MCM-41 to the metallic modified Keggin POM materials.
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•PES porous nanofibers were obtained with high specific surface area and high porosity.•PFSA/PES porous catalytic nanofibers were obtained after heat treatment with high PFSA ...loading.•The obtained porous catalytic nanofibers with good catalytic property prior to that of commercial catalyst.
Perfluorinated sulfonic acid (PFSA)/polyether sulfone (PES) porous catalytic nanofiber was fabricated and applied to esterification reaction as catalyst in this work. To this aim, PES porous nanofibers were firstly prepared through electrospinning, and PFSA resin as catalyst was successfully anchored on these PES porous nanofibers through dip-coating method. Mesoporous structure was observed in PES porous nanofibers with high specific surface area of 40.6m2/g. The catalytic properties of PFSA/PES porous catalytic nanofibers were measured by esterification of ethanol and acetic acid as model reaction. The recovery of PFSA/PES porous catalytic nanofibers remained 93.8% after three cycles of esterification, and the ion exchange capacity almost remained at a constant level, showing excellent recovery. For PFSA/PES porous catalytic nanofibers loaded with 5wt% of PFSA as catalyst, the conversion rate and forward reaction kinetics constant achieved 85.8% at 1h and 9.03×10−4m3kmol−1s−1g−1, respectively.
Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to ...contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B1, B2, G1, and G2) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 μg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE.
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•Low-cost humic acid-bound silica (HAS) as the solid-phase extraction (SPE) sorbent.•Direct treatment diluted oil sample without liquid-liquid extraction.•High recoveries for aflatoxins in various edible oils were achieved.•Feeble matrix interference and accurate results comparable to IAC.
This study examined the preparation of isobornyl acetate/isoborneol from camphene using an α-hydroxyl carboxylic acid (HCA) composite catalyst. Through the study of the influencing factors, it was ...found that HCA and boric acid exhibited significant synergistic catalysis. Under optimal conditions, when tartaric acid-boric acid was used as the catalyst, the conversion of camphene and the gas chromatography (GC) content and selectivity of isobornyl acetate were 92.9%, 88.5%, and 95.3%, respectively. With the increase in the ratio of water to acetic acid, the GC content and selectivity of isobornol in the product increased, but the conversion of camphene decreased. The yield of isobornol was increased by adding ethyl acetate or titanium sulfate/zirconium sulfate to form a ternary composite catalyst. When a ternary complex of titanium sulfate, tartaric acid, and boric acid was used as the catalyst, the GC content of isobornol in the product reached 55.6%. Under solvent-free conditions, mandelic acid-boric acid could catalyze the hydration reaction of camphene, the GC content of isoborneol in the product reached 26.1%, and the selectivity of isoborneol was 55.9%. The HCA-boric acid composite catalyst can use aqueous acetic acid as a raw material, which is also beneficial for the reuse of the catalyst.
This study aimed to investigate factors affecting the discarded semen of boars. A total of 176,368 ejaculates of boars from nine AI centers were collected from January 2013 to May 2016 in Southern ...China. The criteria for determining whether their semen was abnormal included cytoplasmic droplets, coiling tail, sperm agglutination, impurity, poor motility, oligozoospermia, necrozoospermia, azoospermia, and hemospermia. The cause of discarded semen was evaluated with a Chi-square test, and the effects of housing type, breed, age at collection, season identified in the northern hemisphere, and age at herd entry of the discarded semen of boars were analyzed with a logistic regression model. Results indicated the proportion of the discarded semen (PDS) in the nine AI centers was 13.09%. Chi-square test showed the greatest PDS among all causes was found in semen discarded due to cytoplasmic droplets (31.60%), followed by impurity (25.96%), sperm agglutination (20.31%), coiling tail (17.72%), oligozoospermia (10.86%), and others (6.78%; P < 0.0001). Logistic regression analysis revealed the PDS was affected by all these five factors (P < 0.0001). The PDS of boars raised individually in stalls was greater than that of boars raised individually in pens (OR: 1.657; 95% CI: 1.607 to 1.709). The PDSs of Duroc boars (OR: 1.130; 95% CI: 1.093 to 1.167) and Yorkshire boars (OR: 1.432; 95% CI: 1.380 to 1.486) were greater than that of Landrace boars. The PDSs of adult boars (aged from 13 to 24 mo, from 25 to 36 mo, and more than 37 mo with OR: 0.800, 0.941, and 0.838, respectively; 95% CI: 0.771 to 0.831, 0.902 to 0.983, and 0.790 to 0.889, respectively) were lower than those of young boars (aged less than 12 mo). The PDSs of semen collected in summer (OR: 1.367; 95% CI: 1.314 to 1.422), autumn (OR: 1.185; 95% CI: 1.138 to 1.234), and winter (OR: 1.159; 95% CI: 1.115 to 1.206) were greater than those of semen obtained in spring. The PDSs of boars introduced at ages of 5–7 mo (OR: 1.432; 95% CI: 1.380 to 1.486) and 10–12 mo (OR: 1.432; 95% CI: 1.380 to 1.486) were greater than those of boars introduced at an age of 8 and 9 mo. In conclusion, logistic regression analysis reveals discarded semen is affected by housing type, breed, age at collection, season, and age at herd entry. More importantly, cytoplasmic droplets is the primary reason for discarding boar semen, and 8 months at herd entry is the most suitable age for boar introduction.
•A logistic regression model was firstly used to study the influencing factors of discarded boar semen.•Cytoplasmic droplets is the primary reason for discarding the semen of boars in Southern China.•Discarded semen is affected by housing type, breed, age at collection, season, and age at herd entry.•8 months at herd entry is the most suitable age for boar introduction.
A rapid identification method for flue-cured tobacco quality was proposed based on Raman spectroscopy. Considering the critical quality factors of flue-cured tobacco-like oil content, softness, and ...glossiness, four statistical methods, random forest,
K
-nearest neighbor, logistic regression, and partial least squares, can effectively improve the accuracy of quality identification. We randomly collected 149 flue-cured tobacco samples from multiple producing areas in China. After Raman spectroscopy analysis, Savitzky–Golay convolution smoothing and multi-scatter correction were done. The functional groups were analyzed to select characteristic peaks as features for discriminant analysis. The results show that the Raman spectroscopic information can distinguish the quality of flue-cured tobacco with an accuracy greater than 95%, whereas the partial least-squares approach delivers an accuracy of 100%. We conclude that Raman spectroscopy can be considered a vital avenue for identifying the quality of flue-cured tobacco.
Six novel mixed-ligand complexes, Cd(MCPA)
2
(bbhb)
n
(1), Cd(MCPA)
2
(bib)
2
n
(2), Co
2
(MCPA)
4
(pbix)
2
(3), Zn(MCPA)
2
(pbix)
2
n
(4), Cd(MCPA)
2
(obix)
2
n
(5), and Co(MCPA)
2
(obix)
2
n
...(6), have been synthesized under hydrothermal conditions and structurally characterized, where MCPAH = 2-methyl-4-chlorophenoxyacetic acid, bbhb = 1,1′-(1,4-butanediyl)bis-1H-benzimidazole, bib = 1,4-bis(imidazol-1-yl)-butane, pbix = 1,4-bis(imidazol-1-ylmethyl)benzene and obix = 1,2-bis(imidazol-1-ylmethyl)benzene. X-ray diffraction analyses reveal that the N-donor ligands bridge the metal centers into different 1 D chains in complexes 1, 2, 4, 5, and 6, while three is a dinuclear molecule containing 26-membered ring. Furthermore, the luminescent properties of 1, 2, 4, and 5 are also presented.
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Two novel compounds (1–2), together with two known compounds 3 (Pinophilins B) and 4 (Sch 725680) were isolated from the fermentation broth of fungus of Talaromyces aculeatus ...(DS-62013). Absolute configuration (AC) of compound 1 was deduced by comparison of experimental and calculated optical rotation (OR), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) with those of its derivative 1a. Since both OR and ECD methods cannot provide the convincible data for AC identification, and VCD was used in the AC study. The AC of compound 2 was also determined.
•Difunctional membranes performed high catalytic and separating performances simultaneously.•The methyl laurate production process was optimized in the membrane reactor.•A kinetics model was ...established and agreed well with experimental results.
Difunctional hollow fiber ceramic composite membranes with self-sufficient catalysis and separation properties were successfully fabricated through thermal imidization, followed by dip-coating method. The structure, separation and catalysis properties of the fabricated difunctional membrane were investigated by SEM, pervaporation dehydration of methanol aqueous solution, and esterification of methanol and lauric acid to produce methyl laurate in a membrane reactor, respectively. The results showed that the obtained difunctional membrane was characterized by a multilayer structure: a sponge-like support layer, a dense separation layer and a porous catalysis layer. The porous catalysis layer had little effect on separation property. But it provided a large specific surface area for perfluorosulfonic acid (PFSA), resulting in a good catalytic effect. The obtained difunctional membrane also showed an excellent stability and repeatability. The optimized operating conditions were methanol to lauric acid ratio of 10:1, reaction temperature of 70°C, and catalyst dosage of 1.0wt% in this work. A mathematical model was established to describe this experimental process and the predicted results agreed well with the experimental results.
