Exploring complications following cranioplasty after decompressive hemicraniectomy: A retrospective bicenter assessment of autologous, PMMA and CAD implants.

Cranioplasty (CP) after decompressive hemicraniectomy (DHC) is a common neurosurgical procedure with a high complication rate. The best material for the repair of large cranial defects is unclear. The aim of this study was to evaluate different implant materials regarding surgery related complications after CP. Type of materials include the autologous bone flap (ABF), polymethylmethacrylate (PMMA), calcium phosphate reinforced with titanium mesh (CaP-Ti), polyetheretherketone (PEEK) and hydroxyapatite (HA). A retrospective, descriptive, observational bicenter study was performed, medical data of all patients who underwent CP after DHC between January 1st, 2016 and December 31st, 2022 were analyzed. Follow-up was until December 31st, 2023. 139 consecutive patients with a median age of 54 years who received either PMMA (56/139; 40.3%), PEEK (35/139; 25.2%), CaP-Ti (21/139; 15.1%), ABF (25/139; 18.0%) or HA (2/139; 1.4%) cranial implant after DHC were included in the study. Median time from DHC to CP was 117 days and median follow-up period was 43 months. Surgical site infection was the most frequent surgery-related complication (13.7%; 19/139). PEEK implants were mostly affected (28.6%; 10/35), followed by ABF (20%; 5/25), CaP-Ti implants (9.5%; 2/21) and PMMA implants (1.7%, 1/56). Explantation was necessary for 9 PEEK implants (25.7%; 9/35), 6 ABFs (24.0%; 6/25), 3 CaP-Ti implants (14.3%; 3/21) and 4 PMMA implants (7.1%; 4/56). Besides infection, a postoperative hematoma was the most common cause. Median surgical time was 106 min, neither longer surgical time nor use of anticoagulation were significantly related to higher infection rates (p = 0.547; p = 0.152 respectively). Ventriculoperitoneal shunt implantation prior to CP was noted in 33.8% (47/139) and not significantly associated with surgical related complications. Perioperative lumbar drainage, due to bulging brain, inserted in 38 patients (27.3%; 38/139) before surgery was protective when it comes to explantation of the implant (p = 0.035). Based on our results, CP is still related to a relatively high number of infections and further complications. Implant material seems to have a high effect on postoperative infections, since surgical time, anticoagulation therapy and hydrocephalus did not show a statistically significant effect on postoperative complications in this study. PEEK implants and ABFs seem to possess higher risk of postoperative infection. More biocompatible implants such as CaP-Ti might be beneficial. Further, prospective studies are necessary to answer this question.

Germline immortality relies on TRIM32-mediated turnover of a maternal mRNA activator in C. elegans.

How the germ line achieves a clean transition from maternal to zygotic gene expression control is a fundamental problem in sexually reproducing organisms. Whereas several mechanisms terminate the maternal program in the soma, this combined molecular reset and handover are poorly understood for primordial germ cells (PGCs). Here, we show that GRIF-1, a TRIM32-related and presumed E3 ubiquitin ligase in Caenorhabditis elegans, eliminates the maternal cytoplasmic poly(A) polymerase (cytoPAP) complex by targeting the germline-specific intrinsically disordered region of its enzymatic subunit, GLD-2, for proteasome-mediated degradation. Interference with cytoPAP turnover in PGCs causes frequent transgenerational sterility and, eventually, germline mortality. Hence, positively acting maternal RNA regulators are cleared via the proteasome system to avoid likely interference between maternal and zygotic gene expression programs to maintain transgenerational fertility and acquire germline immortality. This strategy is likely used in all animals that preform their immortal germ line via maternally inherited germplasm determinants.

Multifunctional Ceramic Composite System for Simultaneous Thermal Protection and Electromagnetic Interference Shielding for Carbon Fiber-Reinforced Polymer Composites.

Achieving a high electrical conductivity while maintaining a good thermal insulation is often contradictory in the material design for the goal of simultaneous thermal protection and electromagnetic interference shielding. The reason is that materials with a high electrical conductivity often pertain a high thermal conductivity. To address this challenge, this study reports a multifunctional ceramic composite system for carbon fiber-reinforced polymer composites. The fabricated multifunctional ceramic composite system has a multilayer structure. The polymer-derived SiCN ceramic reinforced with yttria-stabilized zirconia fibers serves as the thermal protection and impedance-matching layer, while the yttria-stabilized zirconia fiber-reinforced SiCN ceramic with carbon nanotubes provides the electromagnetic interference shielding. The thermal conductance of the multilayered ceramic composite is about 22.5% lower compared to that of the carbon fiber-reinforced polymer composites. The thermal insulation test during the steady-state condition shows that the hybrid composite can be used up to 300 °C while keeping the temperature reaching the surface of carbon fiber-reinforced polymer composites at around 167.8 °C. The flame test was used to characterize the thermal protection capability under transient conditions. The hybrid composite showed temperature differences of 72.9 and 280.7 °C during the low- and high-temperature settings, respectively. The average total shielding efficiency per thickness of the fabricated four-layered ceramic composite system was 21.45 dB/mm, which showed a high reflection-dominant electromagnetic interference shielding. The average total shielding efficiency per thickness of the eight-layered composite system was 16.57 dB/mm, revealing a high absorption-dominant electromagnetic interference shielding. Typical carbon fiber-reinforced polymer composites reveal a reflection-dominant electromagnetic interference shielding. The electrons can freely move in the percolated carbon nanotubes within the inner layers of the composite material, which provide the improved electromagnetic interference shielding ability. The movement of electrons was impeded by the top and bottom layers whose thermal conduction relies on the lattice vibrations, resulting in a satisfactory thermal insulation of the composite materials and impedance matching with the free space. Results of this study showed that materials with a good thermal insulation and electromagnetic interference shielding can be obtained simultaneously by confining the electron movement inside the materials and refraining their movement at the skin surface.

Ultrahigh-Temperature Ceramic-Polymer-Derived SiOC Ceramic Composites for High-Performance Electromagnetic Interference Shielding.

High-performance electromagnetic interference (EMI) shielding materials for a high-temperature harsh environment are highly required for electronics and aerospace applications. Here, a composite made of ultrahigh-temperature ceramic- and polymer-derived SiOC ceramic (PDC-SiOC) with high EMI shielding was reported for such applications. A total EMI shielding efficiency (SET) of 26.67 dB with a thickness of 0.6 mm at the Ka-band (26.5-40 GHz) was reported for ZrB2 fabricated by spark plasma sintering, which showed reflection-dominant shielding. A unique interface of t-ZrO2 was formed after the introduction of PDC-SiOC into ZrB2. This interface has better electrical conductivity than SiOC. The composites also displayed reflection-dominant shielding. Accordingly, the composite with a normalized ZrB2 fraction of 50% pyrolyzed at 1000 °C exhibited a significant SET of 72 dB (over 99.99999% shielded) with a thickness of 3 mm at the entire Ka-band. A maximum SET of 90.8 dB (over 99.9999999% shielded) was achieved with a thickness of 3 mm at around 39.7 GHz.