At present, silk fibroin (SF) hydrogel can be prepared by means of electrodeposition at 25 V in direct current (DC) mode. Reducing the applied voltage would provide benefits, including lower ...fabrication costs, less risk of high voltage shocks, and better stability of devices. Here, a simple but uncommon strategy for SF-based hydrogel preparation using 4 V in DC mode is discussed. SF was mixed and cross-linked with carboxymethyl chitosan (CMCS) through hydrogen bonding, then co-deposited on the graphite electrode. The thickness, mass, and shape of the SF/CMCS hydrogel were easily controlled by adjusting the electrodeposition parameters. Morphological characterization of the prepared hydrogel via SEM revealed a porous network within the fabricated hydrogel. This structure was due to intermolecular hydrogen bonding between SF and CMCS, according to the results of thermogravimetric analysis and rheological measurements. As a potential wound dressing, SF/CMCS hydrogel maintained a suitable moisture environment for wound healing and demonstrated distinct properties in terms of promoting the proliferation of HEK-293 cells and antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, histological studies were conducted on a full-thickness skin wound in rats covered with the SF/CMCS hydrogel, with results indicating that this hydrogel can promote wound re-epithelization and enhance granulation tissue formation. These results illustrate the feasibility of using the developed strategy for SF-based hydrogel fabrication in practice for wound dressing.
Sericin is a by-product of the silk industry. Its recycling contributes to environmental protection and the sustainable development of the cocoon silk industry. In this paper, on the basis of ...realizing sericin enrichment in solution, the Cu(II) adsorption capacities of sericin-derived carbon (SC), prepared at different pyrolysis temperatures, were studied. SC was characterized using scanning electron microscopy (SEM) and the zeta potential. The effects of the initial concentration of Cu(II), pH, adsorption temperature, and contact time on the adsorption process were evaluated, followed by an investigation of the mechanism of Cu(II) adsorption by SC. The results showed that SC has a porous structure that provides sites for Cu(II) adsorption. The maximum adsorption capacity of Cu(II) onto SC1050, 17.97 mg/g, was obtained at an adsorption temperature of 35 °C and a pH of 5.5. In addition, the pseudo-second-order kinetic model and Langmuir isotherm model correctly described the adsorption process of Cu(II) onto SC1050. Therefore, SC can act as a potential adsorbent for removing Cu(II) from water. This study helps promote the effective use of cocoon silk resources.
The recycling and reuse of biomass waste for the preparation of carbon-based adsorbents is a sustainable development strategy that has a positive environmental impact. It is well known that a large ...amount of silk sericin (SS) is dissolved in the wastewater from the silk industry. Utilizing the SS instead of discharging it into the environment without further treatment would reduce environmental and ecological problems. However, effective enrichment of the SS from the aqueous solution is a challenge. Here, with the help of carboxymethyl chitosan (CMCS), which can form a gel structure under low voltage, an SS/CMCS hydrogel with SS as the major component was prepared via electrodeposition at a 3 V direct-current (DC) voltage for five minutes. Following a carbonization process, an SS-based adsorbent with good performance for the removal of methylene blue (MB) from an aqueous solution was prepared. Our results reveal that the SS/CMCS hydrogel maintains a porous architecture before and after carbonization. Such structure provides abundant adsorption sites facilitating the adsorption of MB molecules, with a maximum adsorptive capacity of 231.79 mg/g. In addition, it suggests that the adsorption is an exothermic process, has a good fit with the
model, and follows the intra-particle diffusion model. The presented work provides an economical and feasible path for the treatment of wastewater from dyeing and printing.
Carbonized silk paves the way for the design and construction of wearable electronics. The composition of silk fibers can be modulated by feeding silkworms with specific diets, which can enhance the ...functionality of the carbonized silk. In our previous work, the silkworms were fed ammonium molybdate tetrahydrate solution sprayed mulberry leaves to obtain carbonized silk fibers (CSF) possessing a maximum specific capacitance of 298 F/g at 0.2 A/g. In this work, we fed the silkworms sodium molybdate solution sprayed mulberry leaves, for which silkworms present a high tolerance, in order to raise the quantity of the element Mo incorporated within the silk. Transmission electron microscopy - energy dispersive X-ray spectroscopy was utilized to observe and analyze grains, grown through the process of carbonization, inside the carbonized silk. It was confirmed that the composition of those grains are MoO2. Electrochemical measurements show these CSF based electrodes possess outstanding capacitance behavior with a specific capacitance of 524 F/g at 0.2 A/g. Additionally, the electrodes show excellent cyclability. The capacitance retention ratio can reach up to 96.84% after 5000 galvanostatic charge/discharge cycles at 0.2 A/g. Our strategy is straightforward and does not require any hazardous or organic solvents, therefore is an illustration of a green procedure for functionalized CSF synthesis. Furthermore, because the precursor fed to silkworm is water soluble and can be easily dispersed over the surface of mulberry leaves, the method described is suitable for bulk and large scale production of functionalized CSF.
A previous study found that the capacitive behavior of nanoparticles fed to the silkworm can be delivered to carbonized silk fibers, which can be used to fabricate electrodes for the construction of ...flexible supercapacitors. However, the tendency of nanoparticles to aggregate decreases the quantity of nanoparticles that enter the silk and therefore reduces the capacitance performance of the prepared carbonized silk. Here, we sprayed ammonium molybdate tetrahydrate (AMT) on the surface of mulberry leaves used for feeding silkworms and investigated the effect of feeding AMT on the growth of silkworms and the properties of spun silk. The precursor incorporated into the silk was converted into scattered MoO
2
NPs, which were embedded within the carbonized silk fiber (CSF)
via
carbothermal reduction. The specific capacitance of CSF obtained from silkworms fed with an aqueous solution of AMT-treated mulberry leaves reached up to 298 F/g at 0.2 g/A, which is much higher than that of the control group (102 F/g). Since AMT is highly water-soluble, and its concentration can be easily modulated, we believe that the proposed strategy is feasible for the large-scale fabrication of CSF with enhanced capacitive performance.
It was found in our previous study that feeding silkworms with MoO2 nanoparticles (NPs) as a food additive enabled the incorporation of MoO2 NPs into the as-spun silk, which, in turn, can be used to ...build electrodes for energy storage. However, aggregation of the MoO2 NPs was observed at high fractional feeding dosages. In order to disperse the MoO2 NPs in fibrous silk and enhance the specific capacitance of the carbonized silk more effectively, a 0.5% (w/v) hydroxypropyl methyl cellulose (HPMC) solution was utilized as the dispersant in this work. Transmission electron microscopy (TEM) results confirmed that HPMC increased the separation of MoO2 nanoparticles incorporated within the silk matrix. Furthermore, the electrochemical performance was characterized, revealing that the specific capacitance of carbonized silk from this HPMC-MoO2 NP feeding group reached 456 F/g, compared to the value of 245 F/g from the previous study, at a current density of 0.2 A/g, demonstrating a significant improvement. The feasibility of utilizing HPMC to maintain the segregated state of MoO2 NPs throughout all stages of silk encapsulation, with negligible impact of this feeding regimen on the growth of silkworms, is demonstrated in this work.
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•Upon in vivo feeding, HPMC can ensure the separation of nanoparticles even after they are encapsulated within silk fibers.•Feeding HPMC to the silkworm enhances the degree of graphitization of the carbonized silk.•Compared with previous results, the specific capacitance of the carbonized silk increased from 245 F/g to 456 F/g.•Our work produced a silk precursor with potential utility as a high-power supercapacitor component.
In this paper a new method is presented for measuring internal pressure of vacuum tubes, without using magnetic fields but using decay velocity of emission current. Firstly, 500muA emission current ...is used to bombard the surfaces of contacts, which removes superfluous adsorbed layers of molecules from contacts surfaces. Secondly, 35muA emission current is used to ionize the residual gas, which yields ion current. The ion current strikes the surfaces of contacts, adsorbs and then becomes new added layers of molecules, which enlarges the work function of contacts material and reduces the emission current. The decay velocity (=Deltaj thetas /Deltat, where Deltaj thetas decay amount, Deltat decay time) of emission current is varied with internal pressure of vacuum tubes. So with certain Deltaj thetas , internal pressure can be determined by measuring Deltat. The relationship of internal pressure with Deltat is deduced in theory and validated by experiment
The detection of SF 6 gas decomposition products is an effective means of diagnosing defects in gas-insulated electrical equipment. Since the ultra-high voltage gas-insulated switchgear chamber is ...large and equipped with adsorbents, the concentration of decomposition products produced by equipment defects is usually lower than the minimum detection limit of on-site testing instruments, resulting in defects that cannot be detected. This paper uses a method that combines cryogenic enrichment with gas chromatography technology to develop a high-precision SF 6 gas decomposition products detection device. The device can detect SF6 decomposition products with a minimum limit of 10 ppb, which provides an effective means for the detection and diagnosis of latent defects in ultra-high voltage gas-insulated switchgear equipment.
C 4 F 7 N /CO 2 gas mixture has excellent insulation and interrupting properties, and is considered to be the most promising SF 6 replacement gas at present. In order to avoid the carbon ...precipitation phenomenon of C 4 F 7 N /CO 2 gas mixture in the process of opening and closing, O2 needs to be added as the second buffer gas. When partial discharge or local overheating occurs, the C 4 F 7 N /CO 2 /O 2 gas mixture will decompose, and the fault in gas-insulated electrical equipment can be determined by detecting the decomposition components of the gas mixture in gas-insulated electrical equipment. However, the existing C 4 F 7 N ICO 2 /O 2 gas mixture decomposition components are difficult to achieve relatively accurate multi-component simultaneous detection. In this paper, the Raman spectra of each single gas and gas mixture of C 4 F 7 N /CO 2 /O 2 gas mixture and its decomposition gas were obtained by simulation, and the spectral characteristics of the characteristic Raman peaks of each gas were investigated. This study provides some basic data for the detection and quantitative analysis of the decomposition components of C 4 F 7 N /CO 2 /O 2 gas mixture, and shows that Raman spectroscopy has great potential in the field of detection of the decomposition components of C 4 F 7 N /CO 2 /O 2 gas mixture.
The incidence of papillary thyroid carcinoma （PTC） has exponentially increased in recent years. Papillary thyroid microcarcinoma （PTMC） accounts for the majority of the reported cases of PTC. The ...debates and crucial issues in PTMC management have received researchers＇ attention. To further improve the clinical management of PTMC in China,
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