Fabrication and testing of bioinspired microstructured alumina composites with sacrificial interpenetrating polymer bonds.

Bioinspired composites exhibit well-defined microstructures, where anisotropic ceramic particles are assembled and bonded by an organic matrix. However, it is difficult to fabricate these composites where both the ceramic particles and organic matrix work together to unlock toughening mechanisms, such as shear dissipation, particle rotation and interlocking, etc, that lead to stiff, strong, and tough mechanical properties. Here, we produce composites inspired by seashells, made of alumina microplatelets assembled in complex microstructures and that are physically bonded by a small amount of interpenetrated polymer network (IPN) made of polyacrylamide (PAM) and poly-N-isopropylacrylamide (PNIPAM). The fabrication employs magnetically assisted slip-casting to orient the microplatelets as desired, andin situgelation of the IPN, followed by drying. The process was successful after carefully tuning the slip casting and gelation kinetics. Samples with horizontal, vertical, and alternating vertical and horizontal microplatelets orientations were then tested under compression. It was found that the IPN threads bonding the microplatelets acted as sacrificial bonds dissipating energy during the compression. Paired with the alternating microstructure, the IPN significantly enhanced the compressive toughness of the composites by 205% as compared to the composites with horizontal or vertical orientation only, with less than 35% reduction on the stiffness. This study demonstrates that microstructure control and design combined with a flexible and tough matrix can effectively enhance the properties of bioinspired ceramic polymer composites.

Microstructured BN Composites with Internally Designed High Thermal Conductivity Paths for 3D Electronic Packaging.

Miniaturized and high-power-density 3D electronic devices pose new challenges on thermal management. Indeed, prompt heat dissipation in electrically insulating packaging is currently limited by the thermal conductivity achieved by thermal interface materials (TIMs) and by their capability to direct the heat toward heat sinks. Here, high thermal conductivity boron nitride (BN)-based composites that are able to conduct heat intentionally toward specific areas by locally orienting magnetically functionalized BN microplatelets are created using magnetically assisted slip casting. The obtained thermal conductivity along the direction of alignment is unusually high, up to 12.1 W m-1 K-1 , thanks to the high concentration of 62.6 vol% of BN in the composite, the low concentration in polymeric binder, and the high degree of alignment. The BN composites have a low density of 1.3 g cm-3 , a high stiffness of 442.3 MPa, and are electrically insulating. Uniquely, the approach is demonstrated with proof-of-concept composites having locally graded orientations of BN microplatelets to direct the heat away from two vertically stacked heat sources. Rationally designing the microstructure of TIMs to direct heat strategically provides a promising solution for efficient thermal management in 3D integrated electronics.

Mechanical properties of dense mycelium-bound composites under accelerated tropical weathering conditions.

Mycelium, as the root of fungi, is composed of filamentous strands of fine hyphae that bind discrete substrate particles into a block material. With advanced processing, dense mycelium-bound composites (DMCs) resembling commercial particleboards can be formed. However, their mechanical properties and performance under the working conditions of particleboards are unknown. Here, we show how weathering conditions affect the DMC stress and elastic modulus. DMC was made using Ganoderma lucidum mycelium grown on a substrate of sawdust and empty fruit bunch. The DMC was then subjected to weathering under tropical conditions over 35 days and tested under flexural, tensile, and compressive loading with reference to international standards. After exposure to specified weathering conditions, the maximum stress in flexure, tension, and compression decreased substantially. The addition of a protective coating improved the resistance of DMC to weathering conditions; however, the difference between coated and uncoated samples was only found to be statistically significant in tensile strength.

Eliminating MRSA transmission in a tertiary neonatal unit-A quality improvement initiative.

BACKGROUND: Health care facility-onset methicillin-resistant Staphylococcus aureus (HO-MRSA) colonization or infection is a major cause of health care-associated infection (HAI) worldwide. HAIs are preventable and considered a health care quality outcome indicator. A quality improvement project to eliminate HO-MRSA transmission was conducted in a tertiary care neonatal unit over a 9-month period, and sustainability data were monitored. The primary aim of this project was to achieve zero transmission of MRSA among all neonatal unit admissions, and secondary aims were to improve hand hygiene (HH) and environmental hygiene compliance to 100%. METHODS: Existing inpatient admission processes, staff HH, and environmental hygiene practices were critically analyzed. Sequential interventions were implemented, including reinforcing staff awareness on infection control practices through regular education and updates, providing "just in time" feedback, ensuring easy availability of cleaning equipment, individualizing items for all patients, keeping personal belongings away from clinical areas, and revising admission work flow for ex-utero transferred babies from other hospitals. RESULTS: The neonatal unit achieved zero MRSA transmission to previously noninfected and noncolonized patients over the 9-month period, and HH and environmental hygiene compliance improved from a preintervention median of 87.1% and 82.2%, respectively, to 100%, which has been sustained to date. CONCLUSIONS: Intensive reinforcement of infection control practices, strict cohorting of ex-utero transfers, universal surveillance on admission, and improvement in HH and environmental hygiene compliance were key to infection prevention and control measures, resulting in elimination of MRSA transmission in our neonatal unit.