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Sea sand exhibits typical features of loose structure, large compressibility and poor consolidation, causing severe challenges for the construction and emergency repair of coastal engineering. A new Hybrid Non-Isocyanate Polyurethane (HNIPU) was utilized as a curing agent to prepare HNIPU-sea sand mixtures (HSM) in this study. A series of uniaxial compression and scanning electron microscopy (SEM) tests were conducted to explore the strength property and microscopic curing mechanism of HSM. As the mass ratio of polyurethane to sea sand increased from 0.1 to 0.7, the uniaxial compressive strength of HSM first increased from 8.75 MPa to 20.09 MPa then decreased to 17.90 MPa. The maximum strength was achieved at a mass ratio of 0.5. The uniaxial compressive strength increased by 79.46% and 58.41% within a temperature range of −10–60 °C and a curing time range of 10–90 min, respectively. Nevertheless, it decreased by 31.06% with an increase from nil to 10% in moisture content. The prediction formula for the uniaxial compressive strength of HSM can be expressed as a function of multiple influencing factors using regression analysis. The main factors affecting the uniaxial compressive strength of HSM are mass ratio, moisture content, curing time, temperature and gradation in sequence. Furthermore, the progressive failure of HSM were identified based on the complete stress-strain curves in conjunction with the failure mode (X-shaped conjugated shear). It is well documented that HNIPU can rapidly fill, encapsulate and cement sea sand and remarkably enhance its strength, ductility and toughness. These research results may provide an effective method for the rapid reinforcement of the beach sand foundation.

Developing materials with large-scale, ultralight, tunable dielectric properties to meet the applications in electromagnetic (EM) pollution management is still a long-standing issue. In this study, a kind of polypyrrole (PPy) aerogel is fabricated on a large scale through the self-assembly of hollow PPy nanofibers. Benefitting from the first reported “seeding” route method, the diameters and dielectric properties of the PPy nanofibers can be controlled by modulating the proportion of hollow PPy nanofiber seeds and pyrrole (Py). By optimizing the component proportion, the hollow PPy nanofiber aerogel can be applied in both microwave absorption and electromagnetic interference (EMI) shielding. It was found that a minimum reflection loss value of −58.73 dB and a wide effective absorption bandwidth of 7.28 GHz were obtained for the seeds and Py proportion of 1:0.5. Moreover, by modulating the proportion to 1:2, the EMI shielding effectiveness of a composite loaded with 20 wt % of hollow PPy nanofiber aerogels can reach 68.92 dB under the thickness of 3.0 mm. A well-defined conductive network of PPy nanofibers and various interface polarizations and multireflections between different PPy nanofibers and hollow pipes may be the main reasons for the excellent performance in EM applications. This work provides a new strategy of hollow PPy nanofiber aerogels for EM protection.

Intervertebral disc (IVD) cells experience a broad range of physicochemical stimuli under physiologic conditions, including alterations in their osmotic environment. At present, the molecular mechanisms underlying osmotic regulation in IVD cells are poorly understood. This study aims to screen genes affected by changes in osmotic pressure in cells of subjects aged 29 to 63 years old, with top-scoring pair (TSP) method. Gene expression data set GSE1648 was downloaded from Gene Expression Omnibus database, including four hyper-osmotic stimuli samples, four iso-osmotic stimuli samples, and three hypo-osmotic stimuli samples. A novel, simple method, referred to as the TSP, was used in this study. Through this method, there was no need to perform data normalization and transformation before data analysis. A total of five pairs of genes ((CYP2A6, FNTB), (PRPF8, TARDBP), (RPS5, OAZ1), (SLC25A3, NPM1) and (CBX3, SRSF9)) were selected based on the TSP method. We inferred that all these genes might play important roles in response to osmotic stimuli and age in IVD cells. Additionally, hyper-osmotic and iso-osmotic stimuli conditions were adverse factors for IVD cells. We anticipate that our results will provide new thoughts and methods for the study of IVD disease.