Search

Microplastic pollution is considered to be a major coastal environmental issue worldwide, and studies have confirmed the ubiquitous nature of microplastics on many beaches. To best of our knowledge, no previous study on microplastic pollution has been conducted in the present study area to date. This study examined the microplastic abundance, polymer type, size, shape and color in the sediments of Liuqinghewan Bathing Beach and the fishing port beach of Qingdao, China. Microplastics (1–0.5, 0.5–0.25 and 0.25–0.125 mm) were extracted from beach sediments using a density separation method. Fourier transform infrared (FTIR) spectroscopy was used to determine the chemical composition of the plastics while physical characteristics (size, shape, and color) of microplastics were observed using a stereomicroscope. The average microplastic abundance values with the grain size ranges from 1 to 0.125 mm at Liuqinghewan Bathing Beach and at the fishing port beach were approximately 208 ± 3.5 and 299 ± 5.7 microplastics per kg of dry sand, respectively. The number of microplastic particles with the grain size from 0.25 to 0.125 mm was significantly higher than for the other grain sizes. Microplastics were mainly multicolor fibers in all samples making up a large proportion that exceeded 97%. On the basis of FTIR analysis, the microplastics were shown to be composed of polypropylene and polystyrene at both sites. Microplastic characteristics used to identify their origin revealed high development and industrialization predict the non-point source of microplastics related to their hydrodynamic and geographical conditions. Assessing the distribution and characterization of microplastics on sandy beaches of some regions is not novel but a rather common study. However, the outcomes of current study furnish valuable and novel data for the evaluation of microplastic concentrations in beach sediments, environmental risks in China, and a baseline for future analysis. [ABSTRACT FROM AUTHOR]

This paper presents a Double Imaging Mach-Zehnder Spatial Carrier Digital Shearography (DIM-SCDS) system. Compared to traditional Spatial Carrier Mach-Zehnder shearography, DIM-SCDS has two advantages: one is that it can adjust shearing amount and spatial carrier frequency independently; the other one is that it can measure a larger area with a shorter working distance. Two pairs of imaging lenses and apertures are placed in the two arms of Mach-Zehnder interferometry, respectively. Shearing amount is adjusted by the mirrors in the two arms, and spatial carrier frequency is determined by the angle between the two apertures when they are mapped to the same optical axis. Shearograms of the object under test are recorded using a CCD. Shearogram phases are calculated as the measurement results. Finally, the performance of DIM-SCDS is proved by experiments. [ABSTRACT FROM AUTHOR]

A novel polymeric antioxidant, hydroxyl-terminated polybutadiene-bound 2,2-thiobis(4-methyl-6-tert-butylphenol) (HTPB-IPDI-TPH), was prepared by binding 2, 2-thiobis(4-methyl-6-tert-butylphenol) (TPH) onto hydroxyl-terminated polybutadiene (HTPB) with isophorone diisocyanate (IPDI). Fourier-transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance spectroscopy (13C NMR), and gel permeation chromatography (GPC) were used to characterize the structure of HTPB-IPDI-TPH. The thermal stability of HTPB-IPDI-TPH was studied by thermogravimetry analysis (TGA). The effect of HTPB-IPDI-TPH on thermo-oxidative aging resistance of NR vulcanizates was investigated, and the mechanism of thermo-oxidative aging resistance was preliminarily discussed. The results showed that HTPB-IPDI-TPH contributed better thermal stability and thermo-oxidative aging resistance to NR vulcanizates than TPH. The thermo-oxidative aging resistance of HTPB-IPDI-TPH was more remarkable in the later stage of aging. Attenuated total-reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) analysis showed that the relative content of carbonyl groups of NR vulcanizate with HTPB-IPDI-TPH was obviously lower than that with TPH after thermo-oxidative aging. It is suggested that ‒NHCOO‒ groups in HTPB-IPDI-TPH enhanced the ability of trapping alkyl peroxide radicals. [ABSTRACT FROM PUBLISHER]

A novel polymeric antioxidant HTPB-IPDI-TPH was synthesized by the reaction between 2,2-thiobis (4-methyl-6-tert-butylphenol) (TPH) and an adduct (HTPB-IPDI) from hydroxyl terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI). The effects of raw materials ratio and the reaction condition were investigated by measuring the content of the residual –NCO groups of the reactants during the reaction. The structure of HTPB-IPDI-TPH was characterized by FTIR and 1H NMR. Thermo-oxidative aging resistance of HTPB-IPDI-TPH was evaluated by oxidation induction time (OIT) from DSC of natural rubber vulcanizates. The optimal reaction conditions between IPDI and HTPB were that the amount of dibutyltin dilaurate (DBTDL) was 0.6 wt% based on IPDI, and the temperature and time were 40°C and 270 min, respectively. The reaction conditions between TPH and HTPB-IPDI were that the molar ratio of TPH to –NCO in HTPB-IPDI was 3:1, and the amount of DBTDL was 1.6 wt% based on the total of reactants, and the temperature and time were 75°C and 360 min, respectively. Thermo-oxidative aging resistance of HTPB-IPDI-TPH was obviously superior to the corresponding low molecular counterpart (TPH) for natural rubber vulcanizates. [ABSTRACT FROM AUTHOR]

The solid‐phase microextraction technique (SPME) was used for the measurement of the partition coefficients of eight nitro polycyclic aromatic hydrocarbons (NPAHs) and ten polycyclic aromatic hydrocarbons (PAHs) between the polymeric coating of polydimethylsiloxane used in SPME and water (Ksw). The results demonstrate that the technique is simple, rapid, and reproducible, and thus provides a viable alternative to the conventional methods used for such measurements. There is a strong linear correlation between logKsw and the commonly used logKow (octanol–water partition coefficient) for PAHs, NPAHs, PCBs, and simple aromatics. The logKow values for NPAHs range from 2.78 to 4.75, and exhibit a general increase in value with increasing molecular weight. NPAHs are thus noticeably less hydrophobic than their parent PAHs counterparts, for which the log Kow values range from 3.35 to 5.20. [ABSTRACT FROM AUTHOR]

An electrochemical aptasensor was established for the fast and sensitive determination of tetracycline based on the synergistic effect of MoS2-thionine nanocomposite and aptamer. The glassy carbon electrode was coated with MoS2 nanosheets of thionine to immobilize the tetracycline aptamer. In the absence of tetracycline, large quantities of thionin were loaded on the surface of the MoS2 nanosheet to serve as the electrochemical probe. After tetracycline was added to the surface of the electrode, an aptamer analyte complex was produced on the modified electrode. Through intercalation and electrostatic interactions, the complex was substantially adsorbed onto thionine, and the peak currents of the redox signal of thionine decreased. Therefore, the concentration of tetracycline was monitored by the change in signal intensity. Under optimized conditions, the developed electrochemical strategy with MoS2-thionine composite and aptamer exhibited an excellent linear detection range of 1.0 nM–1.0 μΜ and a low detection limit of 0.6 nM with suitable selectivity and stability. Therefore, the fabricated platform offers great potential for food safety, medical detection, and drug analysis. [ABSTRACT FROM AUTHOR]

AimsMethodsResultsConclusionTo systematically identify, evaluate and synthesize qualitative evidence about the dignity-related nursing experiences of people with dementia in families and nursing homes, summarize the similarities and differences and analyse the causes and influencing factors.A synthesis of qualitative studies retrieved from eight databases that were published before September 2022. Two reviewers independently screened and selected studies. Inclusion criteria were established according to the PICOS principle. Quality assessment was guided by Joanna Briggs Institute’s Qualitative Assessment and Review Instrument and the structured topic synthesis method was used to summarise studies eligible for inclusion.Three key themes were extracted from 14 included studies; the living environment, relationship needs and self-awareness, which focused on improving the dementia-centred nursing environment, meeting the needs of the relationship-centred nursing network, and finally, improving the self-awareness of people with dementia to promote dignity.This systematic review shows people with dementia need to integrate into society and maintain their dignity in a dementia-friendly environment that is respectful, inclusive environment that promotes freedom. [ABSTRACT FROM AUTHOR]

The dephosphorization slag produced by the duplex steelmaking process is suited for making steel slag phosphate fertilizer. The factors influencing P2O5solubility of dephosphorization slag in citric acid were studied and a series of CaO-SiO2-FetO-P2O5quaternary slag samples were prepared and analyzed. It was demonstrated that the corresponding P2O5solubility varies from 81.6% to 97.9%. The P2O5solubility increases with the increase of CaO/SiO2, CaO/P2O5, CaO/(SiO2+P2O5) and SCA (Surplus Calcium Alkalinity), and decreases with the increase of both FetO and P2O5content. Halide content has a notable negative effect on solubility in citric acid. The P2O5solubility decreases from 92.5% to 47.1% with 1.0% CaF2added. When the content of CaF2reaches 6.0%, the solubility of slag is only 13.7%. With 2.0% and 5.0% CaCl2added, the P2O5solubility decreases from 92.5% to 81.9% and 79.8%, respectively. In order to get a higher soluble slag, fluorine-containing and chlorine-containing substances cannot be added into the steelmaking converter. The addition of MgO and MnO has a positive influence on the P2O5solubility in citric acid. The addition of Al2O3shows an opposite influence. Na2O can significantly improve the P2O5solubility in citric acid solution. [ABSTRACT FROM PUBLISHER]

Shearography is only sensitive to deformation in the shearing direction, and the deformation of object defects after loading may occur in multiple directions. This work reports a multi-direction shearography system that uses spatial phase-shift methods to detect the object from multi-shearing directions, effectively avoiding the missed detection of directional defects. A single laser is utilized to illuminate an object, and a single CCD camera records images in the multiplexed Mach–Zehnder interference system. First, the aperture stops in suitable size and location are set to produce different spatial carrier frequencies. Second, the shearing amount is independently adjusted by using different devices. Finally, the Fourier transform method is used to extract the phase information from the frequency domain. This system can be used for nondestructive testing of multi-directional defects and the feasibility of the method is verified by theoretical analysis and experiment. [ABSTRACT FROM AUTHOR]

Pyruvate oxidase (PyOD) is a very powerful enzyme for clinical diagnostic applications and environmental monitoring. Influences of temperature on cell growth, plasmid stability, and PyOD expression during the PyOD fermentation process by recombinant Escherichia coli were investigated. Based on the influences of temperature on the physiological metabolism, a novel high-cell density fed-batch cultivation with gradient temperature decrease strategy for effective PyOD production was achieved, under which the biomass (OD600) of recombinant E. coli could reach to 71 and the highest PyOD activity in broth could reach to 3,307 U/L in 26 hr fermentation. [ABSTRACT FROM AUTHOR]

The bones of channel catfish (Ictalurus punctatus), a kind of fish processing waste, were hydrolyzed with one of five proteases (alcalase, neutrase, papain, pepsin, and trypsin) in order to generate antibacterial agents. The antibacterial activity of hydrolysates recovered through enzyme hydrolysis was tested by radial diffusion assay (RDA). Pepsin hydrolysate was found to have the greatest antibacterial activity. Thus, the conditions of hydrolysis with pepsin were optimized by response surface methodology (RSM). After screening and optimization, a quadratic model was proposed. The model predicted that the maximum diameter of clear zone, which suggests the optimum antibacterial activity, was around 20.2 mm with a hydrolysis condition of pH 3.5, reaction temperature of 40°C, enzyme-substrate ratio of 1.97/100 (g/g), substrate concentration of 0.15 g/mL, and reaction time of 4 h. Verification experiments under this condition showed a clear zone of 19.8 mm, which agreed well with the model's predicted value. This result indicates that RSM is an effective way to optimize the enzymatic hydrolysis of channel catfish bones to increase antibacterial activity, and the bones of channel catfish are promising resources for generating antibacterial components. [ABSTRACT FROM AUTHOR]