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BACKGROUND: Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO‐E) with antibacterial and fresh‐keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken. RESULTS: The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (−26.63 ± 1.96 mV). BC/TEO‐E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO‐E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween‐E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO‐E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB‐N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO‐E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups. CONCLUSION: All of the results acquired in the present study indicate that BC/TEO‐E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Electrode materials have significant influence on the performance of supercapacitors. Hence, the synthesis of electrode materials with a low cost and excellent electrochemical performance has immense value. Herein, sodium alginate and carboxylated chitosan were used as raw materials to synthesize nitrogen‐containing porous carbon aerogels (NPCAs). The effect of carbonization temperature on the structure and property of NPCA was studied. The specific surface area of NPCA can reach 2028 m2 g−1. The electrochemical performance of NPCA was tested by using a three‐electrode system and a two‐electrode system. The specific capacitance of NPCA‐800 (800 represents the carbonization temperature) in the three‐electrode system can reach 213.1 F g−1 and 146.8 F g−1 at current densities of 1.0 A g−1 and 10 A g−1, respectively. Meanwhile, NPCA‐800 exhibits an excellent cycle performance and the specific capacitance can retain 91.77 % after 20 000 cycles. The energy density of NPCA‐800 can reach 28.8 Wh kg−1 at a power density of 0.28 kW kg−1 in the two‐electrode system. [ABSTRACT FROM AUTHOR]

Improving the specific capacitance of carbon aerogels in supercapacitors and maintaining their high specific surface area remained an important challenge. Here, we prepared resorcinol-phloroglucinol-formaldehyde carbon aerogels reduced with hydrazine hydrate by a microwave method. The effects of the amount of hydrazine hydrate and the time of microwave reaction on the electrochemical performance of carbon aerogels were investigated. The reductive carbon aerogels were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The XPS spectra of reductive carbon aerogels indicated a presence of four nitrogen N1s groups, three oxygen O1s groups and six carbon C1s groups in the deconvoluted spectra. Surface area analysis and electrochemical performance were also investigated. The results showed that the specific surface area of the N-doped carbon aerogels could be as high as 803 m2 g−1. According to the electrochemical testing results, the specific capacitance of the N-doped carbon aerogels significantly increased and reached 219 F g−1 at a current density of 1.5 A g−1 compared to the pristine carbon aerogels. The optimal dosage and time of hydrazine hydrate was 20.6 mol L−1 for 25 min. The N-doped carbon aerogels electrode exhibited excellent reversibility with a cycling efficiency of 93.6% after 10000 cycles. [ABSTRACT FROM AUTHOR]

Ternary carbon aerogels (CAs) were fabricated via a sol-gel process using resorcinol-formaldehyde (R-F), hydroxyethyl cellulose (HC) and carbon fibers (CFs) in the presence of an acid-base catalyst. The acid-base catalyst was composed of ascorbic acid (VC) and sodium carbonate. The products were carbonized at 900 °C in a nitrogen atmosphere. The effects of the acid-base catalyst on the structure and the electrochemical properties of the resulting CAs were studied. The textural and electrochemical properties were investigated by variable instruments (e.g. scanning electron microscopy (SEM), transmission electron microscopy (TEM), an ASAP 2420 surface-area analyzer, and a GAMRY Interface 1000 electrochemical workstation). These tests showed that, when the molar ratios of F/R, VC/R and Na2CO3/R were 2, 0.02 and 0.002, respectively, and the mass ratios of HC/R and CF/R were 0.09 and 0.005, respectively, the specific surface area of the resulting CA was 1071 m2 g−1 and its specific capacitance was 131 F g−1; both of these values are substantially better than those in prior reports. [ABSTRACT FROM AUTHOR]

Carbon aerogels (CA) with uniform pore structures were prepared by the polycondensation of phloroglucinol, resorcinol, and formaldehyde, using carboxylated chitosan as a soft template. The CA were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and surface area analysis. When carboxylated chitosan was added, the time for wet gel formation was reduced by 60%, and the CA showed a more uniform pore structures. The electrochemical performance of the CA was measured in a three-electrode electrochemical cell. The CA prepared with added carboxylated chitosan showed lower charge transfer resistance on the electrode surface, and the specific capacitances were also enhanced, showing a specific capacitance as high as 135 F/g at a resorcinol-to-carboxylated chitosan mass ratio of 250:1 at a current density of 0.5 A/g. This specific capacitance is much higher than that of the CA without carboxylated chitosan. The capacitance retention under increasing discharge current density was also enhanced by the addition of carboxylated chitosan. The electrochemical performance of the CA in different electrolytes (1 M LiOH, 1 M NaOH, 1 M KOH, 3 M KOH, 6 M KOH, and 9 M KOH) was investigated. The results show that the electrochemical performance in 6 M KOH was better than those in other electrolytes. [ABSTRACT FROM AUTHOR]

Carbon aerogels were synthesized through a sol-gel process by polycondensation of phloroglucinol, resorcinol and formaldehyde, using salicylic acid, m-hydroxybenzoic acid, gallic acid, oxalic acid and succinic acid as the acid catalyst, respectively. The effects of reactants solution pH values on the gel time were studied, and the structure of carbon aerogels was characterized by X-ray diffraction and scanning electron microscopy. The specific surface area, pore size distribution and pore volume were measured by surface area analyzer. Electrochemical properties of carbon aerogels were measured by cyclic voltammetry and galvanostatic charge/discharge measurements. The results show that the gel time was the shortest and the specific surface area of carbon aerogel was the highest, up to 753 m g, and the specific capacitance was 97 F g at pH 1.58 in the presence of oxalic acid. [ABSTRACT FROM AUTHOR]

Drug-resistant bacterial infections exhibit a major threat to public health. Thus, exploring a novel antibacterial with efficient inhibition is urgently needed. Herein, this paper describes three types of MSNs (MSNs-FC2-R1, MSNs-FC2-R0.75, MSNs-FC2-R0.5) with controllable pore size (4–6 nm) and particle size (30–90 nm) that were successfully prepared. The MSNs were loaded with tetracycline hydrochloride (TCH) for effective inhibition of Escherichia coli (ATCC25922) and TCH-resistant Escherichia coli (MQ776). Results showed that the loading capacity of TCH in three types of MSNs was as high as over 500 mg/g, and the cumulative release was less than 33% in 60 h. The inhibitory rate of MSNs-FC2-R0.5 loaded with TCH against E. coli and drug-resistant E. coli reached 99.9% and 92.9% at the concentration of MIC, respectively, compared with the other two types of MSNs or free TCH. Modified MSNs in our study showed a great application for long-term bacterial growth inhibition. [ABSTRACT FROM AUTHOR]

d-cysteine (d-cys) has been demonstrated to possess an extraordinary antibacterial activity because of its unique steric configuration. However, inefficient antibacterial properties seriously hinder its wide applications. Here, cysteine-functionalized gold nanoparticles (d-/l-Au NPs) were prepared by loading d-/l-cysteine on the surface of gold nanoparticles for the effective inhibition of Escherichia coli (E. coli) in vitro and in vivo, and the effects on the intestinal microflora in mice were explored during the treatment of E. coli infection in the gut. We found that the antibacterial activity of d-/l-Au NPs was more than 2–3 times higher than pure d-cysteine, l-cysteine and Au NPs. Compared with l-Au NPs, d-Au NPs showed the stronger antibacterial activity, which was related to its unique steric configuration. Chiral Au NPs showed stronger destructive effects on cell membrane compared to other groups, which further leads to the leakage of the cytoplasm and bacterial cell death. The in vivo antibacterial experiment illustrated that d-Au NPs displayed impressive antibacterial activity in the treatment of E. coli-infected mice comparable to kanamycin, whereas they could not affect the balance of intestinal microflora. This work is of great significance in the development of an effective chiral antibacterial agent. [ABSTRACT FROM AUTHOR]

In the present study, nanoscale rod-shaped manganese oxide (MnO) mixtures were successfully prepared from graphitic carbon nitride (C3N4) and potassium permanganate (KMnO4) through a hydrothermal method. The as-prepared MnO nanomixtures exhibited high activity in the adsorption and degradation of methylene blue (MB). The as-synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Furthermore, the effects of the dose of MnO nanomixtures, pH of the solution, initial concentration of MB, and the temperature of MB removal in dye adsorption and degradation experiments was investigated. The degradation mechanism of MB upon treatment with MnO nanomixtures and H2O2 was studied and discussed. The results showed that a maximum adsorption capacity of 154 mg g−1 was obtained for a 60 mg L−1 MB solution at pH 9.0 and 25 °C, and the highest MB degradation ratio reached 99.8% under the following optimum conditions: 50 mL of MB solution (20 mg L−1) at room temperature and pH ≈ 8.0 with 7 mg of C, N-doped MnO and 0.5 mL of H2O2. [ABSTRACT FROM AUTHOR]

Environmental problems caused by metal ions have caused widespread concern in recent years. In this work, carbon aerogels (CAs) adsorbing different metal ions were prepared. The adsorption performance and kinetics of metal ions (Cu(II), Cr(VI), and Fe(III)) on carbon aerogels were systematically investigated. The results indicated that the maximum adsorption capacity of Cu(II) was 424 mg·g−1 in 600 mg·L−1 copper solution. Adsorption performances of Cu(II), Cr(VI), and Fe(III) on CAs well fitted with a pseudo-second-order kinetic model. The structures and morphologies of metal-containing samples were characterized by scanning electron micrographs (SEM), Energy Dispersive Spectrometer (EDS), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results demonstrated that the texture and electrochemical performance of CAs adsorbing metal ions exhibited a clear change. The specific surface area of CAs for adsorbing copper ions was 450 m2·g−1 and they showed a small average pore diameter (7.16 nm). Furthermore, CAs adsorbing metals could be used for the super capacitor. The specific capacitance of CAs adsorbing copper ions could reach 255 F·g−1 at a current density of 1.0 A·g−1. The CA-Cu electrode materials exhibited excellent reversibility with a cycling efficiency of 97% after 5000 cycles. [ABSTRACT FROM AUTHOR]