Research has shown that the DNA molecule can not only store genetic information but also serve as a polymeric biomolecule for the fabrication of functional materials. The unique precise molecular recognition capability and sequence programmability, combined with its good biocompatibility and biodegradability, impart the DNA molecule considerable potential for use in the construction of multifunctional materials. Depending on the composition, DNA-based materials have been generally categorized into pure DNA materials that are entirely composed of DNA and hybrid DNA materials that are composed of DNA and other functional compositions. Recently, we have developed a series of DNA-based materials that can be applied in diagnosis and therapy, and this review summarizes the relative work. Although challenges still exist regarding the real applications of DNA-based materials such as the high cost of DNA, the difficulty in scale-up, and the low resistance to nuclease, we believe that these drawbacks will be overcome with the development of technology, and new opportunities will emerge in the field of diagnosis and treatment.
The adsorption performance of toluene on ultra-stable Y zeolite (USY) was studied via dynamic adsorption. The effects of bed temperature, initial concentration, and feed flow rate on adsorption were investigated. The Yoon–Nelson model was used to fit the toluene breakthrough curves. The length of mass transfer zone was calculated based on breakthrough curves. The Langmuir–Freundlich model fit the adsorption isotherms of toluene on USY, which indicated that the surface of USY was heterogeneous. The adsorption isosteric heat calculated from adsorption isotherms ranged from 54.3 to 69.8 kJ/mol, indicating physical adsorption. The combined technique of temperature swing adsorption with vacuum swing adsorption (TVSA) exhibited excellent desorption performance, which was attributed to the low desorption activation energy. Under optimized TVSA conditions, the desorption rate of toluene reached 90.6% within 10 min. The long-term cyclic utilization results indicated that the adsorption capacity of USY was stable.
A high-efficiency liquid dishwashing detergent was prepared by using oregano essential oil as an antibacterial agent. The surface cleaning and antibacterial property of the detergent resolved its unifunctionality problem. The antibacterial activities of the detergent were demonstrated through a disk diffusion assay and wipe experiments with Escherichia coli and Staphylococcus aureus. Results showed that the prepared detergent was highly effective against E. coli and S. aureus. The results of chemical accelerated tests indicated that the detergent would be effective for at least 1 year. The antibacterial property and detergency performance of the high-efficiency antibacterial liquid dishwashing detergent were compared with those of a commercial antibacterial detergent containing 0.02% o-phenylphenol. The detergency performance of the high-efficiency detergent reached 97.8% and was superior to that of the commercial antibacterial detergent.
To elucidate feasible routes of producing CO from CH3 and unravel the effect of adsorbed O on CH x transformation, the reactivity of CH x (x = 1–3) with and without the assistance of adsorbed atomic O on Ni(111) was explored using density functional theory calculations. The adsorption energies of CH x (x = 0–3) were found to be significantly reduced on an O-preadsorbed Ni(111) surface compared to a pure surface. Furthermore, O-assisted one-step dehydrogenation of CH x (x = 1–3) features energy barriers and thus is difficult to proceed. In terms of energy, the direct dissociation of CH3 is favorable, except for the last CH dehydrogenation, which is energy intensive. Interestingly, in O-assisted two-step CH transformation to CO via CHO intermediate, the barrier is dramatically lowered. The successive dehydrogenations of CH xO (x = 1–3) were also found to be a route for CO formation. Finally, two possible pathways from CH3 to CO are proposed: (a) CH3 → CH2 → CH → CHO → CO; (b) CH3 → CH3O → CH2O → CHO → CO.
Bismuth vanadate is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its activity and stability need to be further improved. In this work, we synthesized Ni-doped BiVO4 abundant with V4+ species and oxygen defects through an in situ electrodeposition method. The effective doping can decrease the particle size of BiVO4 and lead to the formation of V4+ species/oxygen defects. Accordingly, the doped and defective BiVO4 showed high optical absorption and rapid charge transfer, and further showed much higher PEC activity than pure BiVO4. Specifically, 5-Ni-BiVO4 exhibits the highest activity in PEC water splitting, with a photocurrent of 2.39 mA/cm2 at 1.23 V versus RHE (the reversible hydrogen electrode), which is 2.5 times higher than pure BiVO4 (0.94 mA/cm2), and much higher incident photon-to-current efficiency (IPCE) value of 45% (while only 25% for BiVO4 at ca. 400 nm). This work provides an in situ method for the development of a high-performance photoanode.
Batch crystallization in acidic aqueous solution of cephalexin was conducted by reactive crystallization with or without seeding. Supersaturation was generated by mixing ammonia and acidic aqueous solution of cephalexin and controlled by solution feeding rate and seeding conditions. UV and Morphologi G3 were used to measure supersaturation and aspect ratio. Experimental results demonstrated that burst nucleation occurred and the products were needle-like at high supersaturation; meanwhile, the products were plate-like and had high aspect ratio at low supersaturation. Analysis of the measured supersaturation profiles and corresponding aspect ratio explained the mechanisms governing the aspect ratio. The optimized operating parameters were also proposed (seeding supersaturation is equal to 1.3, seed mass ratio 8% and feeding rate 368 μL/min).
SsrA peptide tag from Mycoplasma florum has been developed as a versatile biotechnology tool to control orthogonal degradation of tagged proteins in Escherichia coli. Here, using the systematic deletion mutants of mf-ssrA tag, we demonstrated that the residues in two separate regions have different functions in mf-Lon-mediated specific orthogonal target protein degradation in E. coli. The deletion of multiple residues, up to six amino acids, did not fatally abolish its specific degradation activity, instead of being able to improve the stability of the tagged protein in the presence of endogenous proteases before mf-Lon expression in E. coli. Except for previously identified essential residues, the region adjacent to the C-terminal of the mf-ssrA tag was involved in mf-Lon and endogenous protease-mediated degradation. Moreover, the deletion of specific residues made the mf-ssrA tag more effective and compact. The mf-ssrA tag can be implemented in synthetic biology and bioengineering for development of synthetic circuits.
Unlike the adverse effect caused by the gelation during crystallization process, gelation of cefpiramide sodium was found to provide ideal product properties, such as a larger and more regular crystal shape. The causes of the gelation phenomenon and the mechanism of gel–crystal transition during the crystallization of cefpiramide sodium were both investigated in this work. The gel was formed due to the strapping of the solvents by the networks of cefpiramide sodium molecules. The whole gel–crystal transition process was divided into the following three stages: (1) when the temperature decreased, the system reached a metastable-state gelation; (2) the initial microcrystal in the gel grew slowly because of the low supersaturation; and (3) the gel finally disappeared, and a larger and more regular crystal was formed. The Hansen solubility parameters were used to analyze the effects of the solvents on this gelation; the analysis results can serve as guidance for solvent screening in the actual production process.
Natural pyrites contain high levels of adsorbed and structurally incorporated arsenic (As), which may simultaneously result in the release of As and affect the oxidation process of pyrite. However, the oxidation and electrochemical behaviors of As on the oxidation reactivity of pyrites are still not clear. In this study, pyrite was prepared by a hydrothermal method and applied to study the oxidation mechanism between pyrite and aqueous arsenate. Analyses of X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy demonstrate that the as-prepared sample is an octahedron-like pyrite with high purity and crystallinity. The interaction between As(V) and pyrite as well as the electrochemical behaviors of pyrite oxidation in the presence of aqueous arsenate were investigated under acidic conditions by an ion analysis method, cyclic voltammetry (CV), Tafel, and electrochemical impedance spectroscopy (EIS). The results of the chemical reaction indicate that electrons are transferred from S2 2− to dissolved oxygen with the formation of SO4 2− in the initial As(V) concentration range of 0–0.3 mmol/L. In the initial As(V) concentration range of 0.4–1.2 mmol/L, electrons are transferred from S2 2− to As(V) with the formation of elemental S0 and As(III). The CV, the Tafel plot and EIS analyses indicate that aqueous arsenate in an electrolyte promotes oxidation reactivity and passivation of the pyrite electrode. Moreover, the electron transfer rate increases with increasing aqueous arsenate concentration in the electrolyte.
The hydrodynamic characteristic of a new rotating stream tray (NRST) was investigated. The tests were carried out using an air–water/oxygen experimental system in a column with a diameter of 500 mm. The hydrodynamic parameters studied were dry plate pressure drop, wet plate pressure drop, weeping, entrainment, and Murphree liquid efficiency. The results showed that the NRST has excellent performance in terms of high operational flexibility. The pressure drop, weeping rate, and entrainment rate remained low even under a high-capacity operation. Correlations of pressure drop, weeping, and entrainment for the NRST were obtained by regression analysis. The results can provide some important theoretical guidance for the development of this type of trays.
This study evaluated the changes in sugar metabolism and fruit quality of different pear cultivars during cold storage using seven major commercial pear cultivars belonging to different Pyrus species, such as P. bretschneideri Rehd. (“Huangguan,” “Yali”), P. pyrifolia Nakai. (“Wonhwang,” “Hosui”), P. ussuriensis Maxim. (“Jingbai,” “Nanguo”), and P. communis L. (“Bartlett”). The firmness, respiration rate, titratable acidity, total soluble solids, sugar content, and enzyme activity of the seven pear cultivars were investigated. SPSS was used for analyzing the significance of different indexes. Results showed that fructose was the dominant sugar, accounting for > 60% of total sugars, followed by glucose and sucrose. The respiration peak of almost all cultivars appeared within 60 days. The levels of fructose, glucose, sucrose, and total soluble solids increased within 90 days and then generally decreased. Acid invertase showed the highest activity among all pear cultivars, followed by neutral invertase, sucrose synthetase, and sucrose phosphate synthetase during storage.
To study the influence of the preparation method on Cu active sites and the reaction pathway in NO reduction by NH3 over Cu–SSZ-13, three kinds of catalysts (Cu ion-exchanged SSZ-131, one-pot synthesis Cu–SSZ-132, and Ce0.017–Fe0.017/Cu–SSZ-13 [Ce and Fe ion exchange on the basis of Cu–SSZ-132]) were prepared. In situ diffuse reflectance infrared Fourier transform spectroscopy and H2 temperature program reduction were used to study the differences in the reaction pathways and Cu active sites over the three kinds of catalysts. Density functional theory was employed to study the effect of active sites on the reaction pathway. In situ DRIFTS showed that the reaction pathway on Cu–SSZ-131 during NO oxidation was different from that on Cu–SSZ-132 and Ce0.017–Fe0.017/Cu–SSZ-13. The difference was that intermediate NO2 was involved in the selective catalytic reduction reaction on Cu–SSZ-131, whereas NO2 was not found during the reaction process on Cu–SSZ-132 and Ce0.017–Fe0.017/Cu–SSZ-13. H2–TPR studies revealed that the three catalysts had different Cu active sites, which were located in the six-membered ring, eight-membered ring, and CHA cage. On the basis of DFT studies, NO and O2 were more conducive to form nitrate when the Cu species was on the six- and eight-membered rings; by contrast, NO and O2 were more conducive to form NO2 in the cage. These results showed that different preparation methods led to various Cu active sites, and varying Cu active sites could lead to different NO oxidation processes.
This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of flax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these findings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were significantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out efficiently and quickly. The mixed system exhibits feasible applications in the fiber and textile industry.
To detect the real-time plasma plume during pulse wave Nd:YAG laser welding, experimental studies were conducted based on asynchronous signal acquisition system. The electrical signals of the laser-induced plasma plume were obtained by a passive acquisition system. The plume was directly observed and recorded using synchronous high-speed camera. The results showed that the waveform of the signals was in accordance with the periodical laser power. The signals decreased after the laser was turned on and fluctuated relatively steadily on the stable stage and then increased to 0 V after the laser beam was turned off. The decreasing time of the electrical signals was roughly 1.0 ms, and it decreased with the increasing peak power. However, the average power had insignificant effect on the signal decreasing time.