Fabrication of Cellulose-Graphite Foam via Ion Cross-linking and Ambient-Drying.

Conventional plastic foams are usually produced by fossil-fuel-derived polymers, which are difficult to degrade in nature. As an alternative, cellulose is a promising biodegradable polymer that can be used to fabricate greener foams, yet such a process typically relies on methods (e.g., freeze-drying and supercritical-drying) that are hardly scalable and time-consuming. Here, we develop a fast and scalable approach to prepare cellulose-graphite foams via rapidly cross-linking the cellulose fibrils in metal ions-containing solution followed by ambient drying. The prepared foams exhibit low density, high compressive strength, and excellent water stability. Moreover, the cross-linking of the cellulose fibrils can be triggered by various metal ions, indicating good universality. We further use density functional theory to reveal the cross-linking effect of different ions, which shows good agreement with our experimental observation. Our approach presents a sustainable route toward low-cost, environmentally friendly, and scalable foam production for a range of applications.

3D-Printed, High-Porosity, High-Strength Graphite Aerogel.

The global demand for plastic foam materials is enormous (annual worth of ≈$341.3 billion) and still surging with an annual growth rate of 4.8%, driven by increasing modern societal needs. The majority of existing foam materials are made of plastics, which take hundreds of years to degrade, leading to severe global pollution issues. Here, a degradable, recyclable, and cost-effective solution to foam materials based on 3D graphite-cellulose nanofibers (G-CNF) foam fabricated from resource-abundant graphite and cellulose via advanced 3D printing is reported. The CNFs can directly disperse the graphite under physical sonication without the need for any chemical reactions. The interaction of the CNFs with graphite through the function of hydrophilic and hydrophobic faces in CNFs renders the dispersion polymer-like rheological properties and good processability with tunable viscosity for 3D printing. A robust, degradable, and recyclable G-CNF foam with designed shapes can be printed in a large scale, demonstrating higher mechanical strength (3.72 MPa versus 0.28 MPa in tensile strength and 2.34 MPa versus 1.11 MPa in compressive stiffness), better fire resistance, degradability, and recyclability than commercial polystyrene foam material. The demonstrated G-CNF foam can potentially replace the commercial plastic foam materials, representing a sustainable solution toward white pollution.

Use of Point-of-Care Ultrasound in the Pediatric and Neonatal Emergency Transport Realm.

Point-of-care ultrasound (POCUS) is a tool often used by clinical providers in the care of critically ill or acutely injured patients. POCUS can be used to evaluate for potentially harmful conditions during transport and to optimize downstream management. Although available literature primarily focuses on adults in the prehospital, critical care, and austere environment realm, more literature supporting POCUS use during pediatric and neonatal transport has emerged over the last few years. What is currently available is often from diverse operators and a wide variety of applications. The goal of this article is to describe current pediatric and neonatal POCUS applications and to identify its barriers and limitations in the transport realm. [Pediatr Ann. 2021;50(10):e432-e436.].

Psychosocial Work Environment and Teachers' Psychological Well-Being: The Moderating Role of Job Control and Social Support.

Nowadays, the issue of teachers' psychological well-being causes serious concern, especially in Malaysia. Many studies related to psychological well-being have focused on students rather than on the health and well-being of teachers. Thus, the current study investigated the determinants of psychological well-being (depression, anxiety and stress) from the psychosocial work environment (job control, job demands and social support), and examined the moderating role of job control and social support in the relationship between job demands and psychological well-being among teachers. The design of this study was quantitative research through a survey questionnaire. The sample consisted of 335 high school teachers (23.3%-male; 76.7%-female) who responded to measuring scales of job demands, job control, social support, depression, anxiety and stress, and socio-demographic profile. The data were analyzed using two statistical methods, namely descriptive and inferential statistics. The hierarchical linear regression model was used to analyze the data by assisting the statistical software, i.e., SPSS-23. The results showed that job demands, job control and social support significantly predicted teachers' psychological well-being. Furthermore, the effect of job demands on teachers' depression and anxiety was partially moderated by job control and social support. In conclusion, this study has successfully identified the significant predictors of teachers' psychological well-being and the role of job control and social support as a moderating variable to teachers' psychological well-being in Malaysia. The result provides insights and contributes to the literature of teachers' psychological well-being determinants and involves Malaysian respondents with a collectivistic eastern culture.

Decoupling Ionic and Electronic Pathways in Low-Dimensional Hybrid Conductors.

The construction of two-dimensional (2D) layered compounds for nanofluidic ion transport has recently attracted increasing interest due to the facile fabrication, tunable channel size, and high flux of these materials. Here we design a nacre-mimetic graphite-based nanofluidic structure in which the nanometer-thick graphite flakes are wrapped by negatively charged nanofibrillated cellulose (NFC) fibers to form multiple 2D confined spacings as nanochannels for rapid cation transport. At the same time, the graphite-NFC structure exhibits an ultralow electrical conductivity (σe ≤ 10-9 S/cm), even when the graphite concentration is up to 50 wt %, well above the percolation threshold (∼1 wt %). By tuning the hydration degree of graphite-NFC composites, the surface-charge-governed ion transport in the confined ∼1 nm spacings exhibits nearly 12 times higher ionic conductivity (1 × 10-3 S/cm) than that of a fully swollen structure (∼1.5 nm, 8.5 × 10-5 S/cm) at salt concentrations up to 0.1 M. The resulting charge selective conductor shows intriguing features of both high ionic conductivity and low electrical conductivity. Moreover, the inherent stability of the graphite and NFC components contributes to the strong functionality of the nanofluidic ion conductors in both acidic and basic environments. Our work demonstrates this 1D-2D material hybrid system as a suitable platform to study nanofluidic ion transport and provides a promising strategy to decouple ionic and electronic pathways, which is attractive for applications in new nanofluidic device designs.