Quantitative Evaluation of the Effects of Salt Concentration and pH on the Self-Assembly of Kaolin Nanoplatelets.

Diffusion of pollutants in the earth's strata threatens both the environment and human health. The clay soil microstructure that plays a crucial role in the diffusion of pollutants is significantly influenced by the pore water chemistry. However, there is still a lack of quantitative evaluation of pore water chemistry on clay fabric evolution. To bring new insights, we systematically examined the impact of water chemistry (mainly refers to salt ion concentration and pH) on the self-assembly form (fabric) of kaolin platelets and evaluated the fabric quantitatively. The results show that as the salt ion concentration increases, the "kaolin book" structure is formed, which can be captured by the (001) and (020) pole figures. Under acidic conditions, kaolin platelets turn randomly arranged; however, with the increase of pH, the edge-to-face (EF) microstructure of kaolin platelets gradually changes to a face-to-face (FF) structure. Under alkali-eq conditions, kaolin platelets form a dispersion assembly dominated by FF repulsion. However, the strong alkaline condition triggers the decomposition of kaolin, leading to a notable decrease in the maximum pole density. The conclusions were substantiated through insightful AFM tests. Moreover, we addressed the advantages and limitations of 1DXRD and 2DXRD by analyzing the trend between the OI and pole density, with 2DXRD being favored for its accuracy. Overall, this study provides insights into clay platelets and the self-assembly of kaolin under different water chemistry conditions, which have significant implications for predicting and modeling the physical properties of clay under special environmental conditions.

Quantitative examination of microstructural transformations of clay-rich sediments in river-dominated deltas under the influence of polluted pore water.

Coastal water pollution has a significant impact on sedimentary environments, altering the microstructure of clay-rich sediments and further destabilizing river-dominated delta strata. However, the understanding of the microstructure of clay sediment, influenced by burial depth and pore water chemistry, remains limited due to challenges in quantitatively analyzing clay texture at varying depths. The perturbable of clay microstructures, and the cost of deep sampling have hindered such efforts. To address this issue, this study aims to quantitatively analyze the clay anisotropy at different depths and pore water chemistry through laboratory-simulated sediment samples by using centrifugal modeling and 2DXRD technology. The results suggest that 1DXRD (Orientation index) is prone to generating incorrect conclusions, whereas 2DXRD (pole density) yields more precise and reliable results. Specifically, the results indicated that the introduction of salt ions promoted clay precipitation and stabilized the oriented microstructure at shallower depths. In acidic solutions, clay sediment still contained a certain proportion of edge to face (EF) microstructure at depths less than 6 m, suggesting higher soil thixotropy and lower strength than that of clay sediments in other types of solutions. Overall, our findings provide valuable insights into the relationship between water pollution, delta disappearance, and ocean acidification, highlighting the urgent need for effective environmental management strategies to prevent further damage to fragile coastal ecosystems.

Possible sarcopenia and its risk factors in a home for seniors in Shanghai.

BACKGROUND AND OBJECTIVES: The Asian Working Group for Sarcopenia (AWGS) recommended various measures for identifying patients with possible sarcopenia in its 2019 consensus. The present survey aimed to assess older adults in a senior home to determine the prevalence and associated factors for possible sarcope-nia and to compare the differences between various assessment pathways based on AWGS 2019 criteria. METHODS AND STUDY DESIGN: This cross-sectional study examined 583 participants of a senior home. Patients with possible sarcopenia were determined through the following four pathways: [I] calf circumference (CC) + handgrip strength (HGS); [II] SARC-F+HGS; (III) SARC-CalF+HGS; and (IV) CC, SARC-F, and/or SARC-CalF+HGS. RESULTS: The four assessment pathways revealed a high prevalence of possible sarcopenia in the older adults in the senior home ([I]=50.6%; [II]=46.8%; [III]=48.2%; [IV]=65.9%). There is significant difference in prevalence between pathway IV and the other pathways (p<0.001). A multivariate analysis revealed that advanced age, risk of malnutrition, malnutrition, high level of care, an exercise frequency of <3 times per week, and osteoporosis were correlated with a higher risk of possible sarcopenia. By contrast, oral nutritional supplements (ONS) reduced the risk of possible sarcopenia. CONCLUSIONS: This survey reported a high prevalence of possible sarcopenia in the older adults of the senior home and determined the associated influencing factors. Furthermore, our findings suggested that pathway IV is the most suitable pathway for the examined older adults which enabled the detection and early intervention of more possible sarcopenia.

Malnutrition and its risk factors in a home for seniors in Shanghai.

BACKGROUND AND OBJECTIVES: Older adults residing in senior homes are at a high risk of malnutrition. In this study, we investigated the nutritional status of these individuals and factors associated with malnutrition in this population. METHODS AND STUDY DESIGN: This cross-sectional study (September 2020-January 2021) included a total of 583 older adults residing in a senior home in Shanghai (mean age, 85.0±6.6 years). The Mini Nutritional Assessment Short Form (MNA-SF) questionnaire was administered to assess the nutritional status of the participants. Patients with possible sarcopenia were identified according to the guidelines recommended by the Asian Working Group for Sarcopenia in its 2019 consensus (AWGS 2019). Moreover, the factors influencing malnutrition were determined through multivariate analyses. RESULTS: The likelihoods of having malnutrition and being at a risk of malnutrition were noted in 10.5% and 37.4% of the participants, respectively. In both male and female participants, handgrip strength (HGS) and calf circumference (CC) increased significantly with increasing scores on the aforementioned questionnaire (p<0.001). Among the participants, 44.6% had ≥3 chronic diseases and 48.2% used multiple medicines. Multivariate analyses revealed that dys-phagia (OR, 3.8; 95% CI, 1.7-8.5), possible sarcopenia (OR, 3.6; 95% CI, 2.2-5.6), and dementia (OR, 4.5; 95% CI, 2.8-7.0) were correlated with a relatively high prevalence of malnutrition/malnutrition risk. Exercise (at least thrice a week) reduced malnutrition risk. CONCLUSIONS: Malnutrition is common among older adults residing in senior homes; therefore, the associated factors must be identified, and appropriate interventions should be administered.

Effects of water chemistry on microfabric and micromechanical properties evolution of coastal sediment: A centrifugal model study.

Water chemistry alteration induced strength weakening of natural sediment, which leads to the differential settlement of infrastructures in coastal areas, has caused numerous disasters and engineering failures. To thoroughly understand the underlying mechanisms of how water chemistry influences the microfabric and mechanical properties evolution of coastal sediments, herein, the authors adopted centrifuge test, X-ray diffraction (XRD), and atomic force microscope (AFM) to quantitatively study the structure anisotropy index (i.e., orientation index (OI)), micromorphological property (i.e., root mean square height (Sq)), and micromechanics (i.e., microscale apparent modulus) of clay sediments in different water chemistry conditions and gravity gradients. The results show that the change rule of OI is: OIsaline > OIalkaline > OIwater > OIacid, along the vertical sedimentary depth. Randomly distributed clay flocs and loose flocculated soil skeleton (mainly consisted by edge-to-face (EF) and edge-to-edge (EE) contact of the kaolinite platelets) are associated with the acidic water chemical conditions. The action of supergravity and face-to-face (FF) repulsive contact mode lead to high degree of anisotropy of kaolinite sediments in alkaline environment. Clay platelets are compacted closely under the synergetic effect of centrifugal pressure and prevailing van der Waals attraction (reduction of electric double layer repulsion) in saline environment. The change of 1/Sq is highly consistent with the change of OI at different depths in different water chemical environments. Along the sedimentary depth (i.e., transition from the normal gravity (1 g) to supergravity (8000 g)), the microscale apparent modulus of kaolinite sediment was found to be the highest in alkaline environment. As the water chemistry changes from alkaline to acidic, however, the microscale apparent modulus of kaolinite aggregate decreased, and it showed the smallest in the saline environment.

Dual-controlled tunable dual-band and ultra-broadband coherent perfect absorber in the THz range.

This paper proposes a vanadium dioxide metamaterial-based tunable, polarization-independent coherent perfect absorber (CPA) in the terahertz frequency range. The designed CPA demonstrates intelligent reconfigurable switch modulation from an ultra-broadband absorber mode to a dual-band absorber mode via the thermally controlled of VO2. The mode of ultra-broadband absorber is realized when the conductivity of VO2 reaches 11850 S/m via controlling its temperature around T = 328 K. In this mode, the CPA demonstrates more than 90% absorption efficiency within the ultra-wide frequency band that extends from 0.1 THz to 10.8 THz. As the conductivity of VO2 reaches 2×105 S/m (T = 340 K), the CPA switches to a dual-band absorber mode where a relatively high absorption efficiency of 98% and 99.7% is detected at frequencies of 4.5 THz and 9.8 THz, respectively. Additionally, using phase modulation of the incident light, the proposed CPA can regulate the absorption efficiency, which can be intelligently controlled from perfect absorption to high pass-through transmission. Owing to the ability of the proposed CPA to intelligently control the performance of light, this study can contribute towards enhancing the performance of stealth devices, all-optical switches and coherent photodetectors.

Palatal expansion and relapse in rats: A histologic and immunohistochemical study.

INTRODUCTION: Rapid palatal expansion is an effective intervention for correcting transverse maxillary deficiency in growing patients. However, relapse after treatment is often observed, and the mechanisms of tissue remodeling during expansion and relapse remain unclear. This study aimed to gain insight into such a mechanism. METHODS: A total of 24 5-week-old male Wistar rats were randomly divided into either the expansion or sham device (control) group. Each rat underwent 7 days of expansion and 7 days of relapse. The width of the dental arch, palatal bone, and suture, as well as the angle of the teeth, were measured. Tissue remodeling in the midpalatal suture was examined using microcomputed tomography and histologic and immunohistochemical analyses. RESULTS: The mechanical expansion force caused an increase in arch width, which relapsed after the removal of force. Bilateral tilting of the teeth and midpalatal suture expansion contributed to the widening of the maxillary arch, and only the relapse of the palatal bone width was observed. Histochemical staining showed that suture tissue remodeling was activated by mechanical force in the expansion group and reverted to the level of the control group after relapse. Immunohistochemistry staining revealed that the expression of cathepsin K, osteocalcin, and collagen type I was higher in the expansion group than that in the control group on day 7; however, the difference dissipated by day 14. CONCLUSIONS: The expansion force stimulated osteogenic activity in the midpalatal suture area. After removal of the expansion force, tissue remodeling went back to the normal level.