Accurate determination of potassium ion (K+) concentration in fingertip blood, soil pore water, pipette solution, and sweat is crucial for performing biological analysis, evaluating soil nutrients levels, ensuring experimental precision, and monitoring electrolyte balance. However, current electrochemical K+ sensors often require large sample volumes and oversized reference electrodes, which limits their applicability for the aforementioned small-volume samples. In this paper, a K+ sensor integrated with a glass capillary and a spiral reference electrode was proposed for detecting K+ concentrations in small-volume samples. A K+-selective membrane (K+-ISM)/ reduced graphene oxide-coated acupuncture needle (working electrode) was spirally wrapped with a chitosangraphene/AgCl-modified Ag wire (reference electrode). This assembly was then inserted into a glass capillary, forming an anisotropic diffusion region of an annular cylindrical gap with width 410 mu m and height 20 mm. It was found that the capillary action of the glass capillary results in a raised liquid level of the sample inside it compared to that in the container, which promotes efficient contact between the small-volume sample and the K+ sensor. Besides, the formed anisotropic diffusion region limits the K+ diffusion from the bulk solution to the K+ISM, which leads to a larger potentiometric response of the K+-ISM. The glass capillary-assembled K+ sensor displays high performance, including a sensitivity 58.3 mV/dec, a linear range 10_ 5-10_ 1 M, and a detection limit 1.26 x 10_6 M. Moreover, it reliably determines K+ concentrations in artificial sweat of microliter volume. These results facilitate accurate detection of K+ concentration in fingertip blood, soil pore water, and pipette solution.

This study investigated the improvement in a type of sand using a geopolymer made of recycled glass powder (RGP) as the base material and sodium hydroxide (NaOH) as the alkaline activator. Using maximum uniaxial compressive strength (UCS), the impact of alkaline activator concentration and the RGP content were investigated to determine the optimum mix design. Groundwater level increments were simulated through a laboratory procedure to study the effect of curing age and capillary action on the behavior of stabilized soil. The UCS of samples at different ages (14, 28, 45, and 60 days) and different degrees of saturation (Sr=0%, 20%, 50%, 80%, and 100%) were determined and their stress-strain diagrams were drawn. Using the stress-strain relationships, UCS, modulus of elasticity (Es), shear modulus (G), and resilient modulus (Mr) of the stabilized soil were estimated. The results showed that fully saturated stabilized samples did not disintegrate and exhibited a considerable UCS of up to 1.88 MPa at the age of 60 days. The greatest observed reduction in the UCS through saturation was between Sr=0 to 20%. To further investigate and validate the mechanical results, chemical and microstructural studies including X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR) were carried out. The results showed that during the curing period, the silicon/aluminum (Si/Al) ratio increased from 2.98 in untreated soil to 4 in stabilized samples, indicating active geopolymerization, which enhanced UCS and reduced the potential for disintegration. Additionally, the crystal size decreased from 53 to 24 nm for the 45-day stabilized samples when the degree of saturation changed from 0% to 100%. This finding suggests that if RGP-based geopolymer-stabilized soil contacts water after fully drying, geopolymerization reactions will resume that involve the dissolution of both crystalline and amorphous phases.

As a key cultural relic protection unit in China, the site of the Lidu Shochu Workshop has suffered deformation damage such as structural loosening and material deterioration following archaeological excavations. By means of on-site geological investigation, engineering geological mapping, drilling and indoor tests, the geotechnical type and spatial distribution characteristics, geotechnical setting and chemical properties of water and soil of the site where the Lidu Shochu Workshop was located were studied, and the main destruction mechanisms of the site remains based on the structural characteristics of the geotechnical setting were analyzed in depth. The results of the present study show that: (1) The site remains is subject to a strong alternating wet and dry conditions due to the site's location within the influence of perched water, the increased evaporation caused by the archaeological excavation that removed the upper layers of rock and soil of the site remains, which allowed for the continuous upward transport of perched water by capillary action, and the dynamic changes in the water table; (2) Due to the compartmentalization of the surrounding setting and the low lateral runoff, the perched water tends to accumulate more soluble salts that lead to a higher mineralization; (3) During the upward transport of water by capillary action, the soluble salts in the perched water are concentrated, crystallized and precipitated under evaporation, resulting in the crystallization of salts on the masonry surface of the site proper, which are mainly magnesium sulphate and calcium sulphate (gypsum); (4) In the crystallization process, magnesium sulphate and calcium sulphate (gypsum) swell in volume and corrode and destroy brick, sandstone and bonding materials, resulting in plaster disruption, weakening or failure of the bond, which lead to structural loosening, spalling and deformation.