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•The membrane can perform oily wastewater separation, stay stable under harsh environments and mechanical abrasion.•The modification layer was transparent and achieved UV-resistant ...property as well.•The preparation process was fast, facile and environmental-friendly.
As oily wastewater issues continue to grow, the treatment of oily wastewater has become urgent an emergency. However, present solutions are restricted by the limited performance of materials. An UV-resist and transparent coating consisting of PDMS and ZnO decorated on a highly stable and self-standing polyimide is reported in this work as a potential solution. The obtained fibrous membranes not only allow high-efficiency (higher than 99%) oily wastewater separation but also show superior UV-resistant activity. Moreover, the superoleophilicity and hydrophobicity of the composite membrane were confirmed to be stable under harsh conditions, and the transparent coating layer has the potential to be applied in other fields. The design of the UV-resistant, transparent and superoleophilic nanofibrous membrane is very practical, and will be quite promising for reducing oily environmental contaminations from waters.
The extraction and quantitative determination of phenolic compounds (including phenolic acids, flavones, flavanols, alkaloid, tannins, procyanidins, and naphthoquinone) from the walnut kernel and its ...pellicle were performed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Effective parameters on the tandem MS conditions, chromatographic conditions, and extraction solvents were evaluated and optimized. Under optimum condition, limits of detection and linearity were 0.000565–33.3 μg/g and 10–1000 ng/mL with
r
-values > 0.9952, respectively. The relative standard deviation from extraction recovery was from 74.27 ± 2.81% to 109.52 ± 4.33%, with precision values of < 15%. The proposed method was applied for simultaneous extraction and determination of phenolic compounds not only in the walnut kernel and its pellicle, but also in other tree nuts.
Walnut is a natural source of antioxidants. Its antioxidant capacity is determined by the distribution and composition of phenolics. The key phenolic antioxidants in various forms (free, esterified, ...and bound) in walnut kernel (particularly seed skin) are unknown. The phenolic compounds in twelve walnut cultivars were analyzed using ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer in this study. A boosted regression tree analysis was used to identify the key antioxidants. Ellagic acid, gallic acid, catechin, ferulic acid, and epicatechin were abundant in the kernel and skin. The majority of phenolic acids were widely distributed in the free, esterified, and bound forms in the kernel but more concentrated in bound phenolics in the skin. The total phenolic levels of the three forms were positively correlated with antioxidant activities (R = 0.76-0.94,
< 0.05). Ellagic acid was the most important antioxidant in the kernel, accounting for more than 20%, 40%, and 15% of antioxidants, respectively. Caffeic acid was responsible for up to 25% of free phenolics and 40% of esterified phenolics in the skin. The differences in the antioxidant activity between the cultivars were explained by the total phenolics and key antioxidants. The identification of key antioxidants is critical for new walnut industrial applications and functional food design in food chemistry.
Little is known about the phytochemical composition of iron walnuts. Differences in the geographical origin of iron walnuts associated with economic benefits should also be examined. In this study, ...the phytochemical composition (fatty acids, Vitamin E, total polyphenols and flavonoids, amino acids, and minerals) of iron walnuts in China was investigated. The results showed that there were significant differences (
p
< 0.05) in the phytochemical composition of iron walnut oils and flours from different regions. Positive (r > 0.5,
p
< 0.05) and negative (r < − 0.5,
p
< 0.05) correlations were found between amino acids/minerals and amino acids/oleic acid, with the highest correlation coefficient (r = 0.742,
p
< 0.05) between Cu and tyrosine. In addition, based on the 12 phytochemical fingerprints selected by random forest, a geographical-origin identification model for iron walnuts was established, with a corresponding correct classification rate of 96.6%. The top three phytochemical fingerprints for the geographical-origin identification of iron walnut were microelements, macroelements, and antioxidant composition, with contribution rates of 61.7%, 18.1%, and 9.9%, respectively.
Cultivar is one of the key factors to that influences the nutritional and commercial values of walnuts. However, differences in the comprehensive chemical components among walnut cultivars and their ...internal formation mechanism are rarely reported. In this study, 49 chemical components of 10 main walnut cultivars from Shanxi Province, China were investigated. Polyphenols, flavonoids and vitamin E were especially rich with the contents of 32.20 mg/g, 16.25 mg/g and 42.37 mg/g, respectively. Highly positive correlations existed among amino acids (r > 0.77,
p
< 0.01), polyphenols-flavonoids (r = 0.85,
p
< 0.01) and α-Vitamin E - γ-Vitamin E (r = 0.93,
p
< 0.01). Some microelements (Tl, Ba and Ni) were negatively correlated with most of the essential amino acids (expect for Cys and Lys), α-Vitamin E and γ-Vitamin E. Based on further analysis of the relationships between chemical component groups, there were 13 canonical variate pairs between microelements and other chemical composition groups was up to 13 pairs (r > 0.8,
p
< 0.01). Then correspondence analysis indicated 17 chemical compositions were typical phytochemical component of these walnut cultivars. Microelements were the major factor that influenced on the comprehensive qualities of walnuts. Finally, walnut cultivars were classified into various industrial developments based on their chemical components. This research demonstrated that differences and relationships of chemical components in walnuts could be efficiently determined and further applied to the food industry.
The diversity of cultivars and variation in phytochemical components pose a great threat to the security of foods that contain walnut. The nutrient values of walnut are stipulated according to ...phytochemical components, which are driven by internal and external factors associated with fruit growth. The objective of this work was to investigate the effects of cultivar and climate zone on the phytochemical components of walnuts. First, differences and relationships of phytochemical components in eleven walnut cultivars harvested from northeastern China were analyzed. Almost all individual phytochemical components among cultivars showed significant differences (p < .05). The results were submitted to correspondence analysis followed by matrix transformation and factor analysis. Fatty acids, amino acids, and minerals (Ca, Na, Fe, Cu, P, and Zn) for the identification and discrimination of eleven walnut cultivars were authenticated. Furthermore, based on essential microelements, essential amino acids, unsaturated fatty acids, and antioxidants, the walnut cultivars realized the precision position in food application. Finally, we confirmed the effects of climate zones on the phytochemical components of walnuts, with variations up to 142%. The climatic factors precipitation and temperature influenced the formation and accumulation of monounsaturated fatty acids, tocopherols, and most minerals. The findings will open promising perspectives for oriented cultivation of walnuts and future application in the food industry.
The differences and relationships of 49 phytochemical components and their influence factor (cultivar and climate zone) were comprehensively analyzed. Based on correspondence analysis and specific nutritive characters, the walnut cultivars realized the precision position in the food industry. Precipitation and temperature were the important climatic factors for the formation of MUFA, Ve, and most of the minerals.
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•A nanofibrous membrane was prepared for contaminated water purification.•The membrane is based on reduced graphene and aromatic polymer.•The membrane can maintain the properties ...under multi-kinds external stimulations.•The membrane is suitable for recycled test without compromising the performance.•This material has great potential to be used at industrial level.
This work proposes an anti-corrosive nanofibrous membrane by combining one-pot solvothermal reduction method and electrospinning technology as a solution to the ever-increasing water pollution issues. Such membrane is made of aromatic polymer-polyimide and further modified by reduced graphene oxide, which maintained the original performance under different external environment and multi-cycled test, and achieved high separation efficiency (99.19%) and flux (2040.04 L m-2h−1) at the same time. The purification process is suitable for various contaminants and different combinations. Additionally, the inherent purification mechanism was fully explored in this study. The practicability of the membrane can be tested for the contaminated water purification, the recycle of poisonous and harmful substances, pre-process of precision extraction and so on.
•The majority phenolics in walnut kernel were free phenolics.•Acetone was better to extract soluble phenolics, and methanol for insoluble bound phenolics.•Jeuglone, kaempferol, ...quercetin-7-o-β-D-glucoside and dihydroquercetin were only found in free phenolics.•There was positive linear correlation between antioxidant activities and total phenolic contents.
The free, esterified and bound forms of 37 phenolic compounds (including hydroxybenzoic acid, hydroxycinnamic acids, flavanols, flavonols and flavones) from walnut kernel (Juglans regia L.) were investigated in this study. Results showed that the majority of walnut phenolics were presented in the free form (51.1%–68.1%), followed by bound (21.0%–38.0%) and esterified forms (9.7%–18.7%). Ellagic acid, gallic acid, ferulic acid, sinapic acid and caffeic acid were widely distributed in three forms. Differently, jeuglone, kaempferol, quercetin-7-o-β-d-glucoside and dihydroquercetin were only found in free phenolics. Among the three forms, free phenolics had the highest radical scavenging activity (IC50: DPPH, 15.5 µg/ml; ABTS, 13.6 µg/ml). The correlation coefficients between the antioxidant activities of phenolics and their corresponding contents were 0.82–0.92. More soluble phenolics (free and esterified forms) could be extracted by acetone, while methanol was better at extracting insoluble bound phenolics.
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The aim of this study is to prepare a fibrous membrane scaffold that possesses a frogspawn structure for high-efficiency oil-water separation. Polyamic acid was first electrospun onto ...a rotating wheel-collector to obtain the fibrous membrane. Subsequently, post-processing by immersion in a polydimethylsiloxane solution and a silica nanoparticles suspension, followed by a thermal treatment generated a frogspawn-structured fibrous membrane. The obtained membrane achieved superhydrophobicity and superoleophilicity, with the water contact angle as high as 155.75° and the oil contact angle lower than 10°. The separation efficiencies of the membrane were higher than 99.55% and the permeate flux was maintained at greater than 4400 L/m2∙h after 20 separation cycles. Additionally, the wettability studies suggested the membrane exhibits high stability because it can resist damages due to high temperature (150 °C), acid/basic conditions and organic/inorganic solvents. These findings indicated that this composite membrane has great potential for use in gravity-driven oil-water separation and can extend the range of its application for treatments of oil spills incident, oily wastewater and spent liquor.
•Notable correlations between pellicle colors and phenolics in kernel without pellicle.•Positive correlations between TPCs of three forms in pellicle and their colors.•Dark walnuts with high contents ...of flavanols, flavones and flavonols in free form.
Although walnut kernels are a rich source of phenolic compounds, little is known about the profiles of phenolic compound forms in various colored-pellicle walnuts, which may be important for product development and utilization. In this work, the free, esterified and bound forms of phenolic compounds in various colored-pellicle walnuts were identified using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry ((UHPLC-MS/MS). The total phenolics (TPCs) in pellicle, kernel without pellicle and whole kernel (with pellicle) were presented in the free form (62.6%) and bound form (1.30 %–12.2 %). Positive correlations were found between the TPCs of three forms in pellicle and the pellicle color, with correlation coefficients of 0.920, 0.990 and 0.940. In addition, the phenolic compounds in free form in the whole kernel (with dark pellicle) demonstrated notable advantages in flavanols, flavones and flavonols contents, particularly (+)-catechin (C) (40.7 μg/g) and epicatechin (EC) (25.8g/g), which were 2–153 times higher than other phenolic compounds in free form. Furthermore, the dark group of esterified phenolic acids showed advantages, particularly ellagic acid (428 μg/g) and gallic acid (130 μg/g).
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