Flat-surface-assisted and self-regulated oxidation resistance of Cu(111).

Oxidation can deteriorate the properties of copper that are critical for its use, particularly in the semiconductor industry and electro-optics applications1-7. This has prompted numerous studies exploring copper oxidation and possible passivation strategies8. In situ observations have, for example, shown that oxidation involves stepped surfaces: Cu2O growth occurs on flat surfaces as a result of Cu adatoms detaching from steps and diffusing across terraces9-11. But even though this mechanism explains why single-crystalline copper is more resistant to oxidation than polycrystalline copper, the fact that flat copper surfaces can be free of oxidation has not been explored further. Here we report the fabrication of copper thin films that are semi-permanently oxidation resistant because they consist of flat surfaces with only occasional mono-atomic steps. First-principles calculations confirm that mono-atomic step edges are as impervious to oxygen as flat surfaces and that surface adsorption of O atoms is suppressed once an oxygen face-centred cubic (fcc) surface site coverage of 50% has been reached. These combined effects explain the exceptional oxidation resistance of ultraflat Cu surfaces.

Therapeutic Potential of 4-Hexylresorcinol in Preserving Testicular Function in Streptozotocin-Induced Diabetic Rats.

It is known that many diabetic patients experience testicular atrophy. This study sought to investigate the effect of 4-hexylresorcinol (4HR) on testicular function in rats with streptozotocin (STZ)-induced diabetes, focusing on testicular weight, sperm motility, histological alterations, and serum testosterone levels to understand the efficacy of 4HR on testes. Our findings reveal that 4HR treatment significantly improves testicular health in diabetic rats. Notably, the STZ group exhibited a testicular weight of 1.22 ± 0.48 g, whereas the STZ/4HR group showed a significantly enhanced weight of 1.91 ± 0.26 g (p < 0.001), aligning closely with the control group's weight of 1.99 ± 0.17 g and the 4HR group's weight of 2.05 ± 0.24 g, indicating no significant difference between control and 4HR groups (p > 0.05). Furthermore, the STZ/4HR group demonstrated significantly improved sperm motility compared to the STZ group, with apoptotic indicators notably reduced in the STZ/4HR group relative to the STZ group (p < 0.05). These results underscore the therapeutic potential of 4HR for maintaining testicular function under diabetic conditions.

Relevant Properties and Potential Applications of Sericin in Bone Regeneration.

The potential of sericin, a protein derived from silkworms, is explored in bone graft applications. Sericin's biocompatibility, hydrophilic nature, and cost-effectiveness make it a promising candidate for enhancing traditional graft materials. Its antioxidant, anti-inflammatory, and UV-resistant properties contribute to a healthier bone-healing environment, and its incorporation into 3D-printed grafts could lead to personalized medical solutions. However, despite these promising attributes, there are still gaps in our understanding. The precise mechanism through which sericin influences bone cell growth and healing is not fully understood, and more comprehensive clinical trials are needed to confirm its long-term biocompatibility in humans. Furthermore, the best methods for incorporating sericin into existing graft materials are still under investigation, and potential allergic reactions or immune responses to sericin need further study.

Quantum electron liquid and its possible phase transition.

Purely quantum electron systems exhibit intriguing correlated electronic phases by virtue of quantum fluctuations in addition to electron-electron interactions. To realize such quantum electron systems, a key ingredient is dense electrons decoupled from other degrees of freedom. Here, we report the discovery of a pure quantum electron liquid that spreads up to ~3 Å in a vacuum on the surface of an electride crystal. Its extremely high electron density and weak hybridization with buried atomic orbitals show the quantum and pure nature of the electrons, which exhibit a polarized liquid phase, as demonstrated by our spin-dependent measurement. Furthermore, upon enhancing the electron correlation strength, the dynamics of the quantum electrons change to that of a non-Fermi liquid along with an anomalous band deformation, suggestive of a transition to a hexatic liquid crystal phase. Our findings develop the frontier of quantum electron systems and serve as a platform for exploring correlated electronic phases in a pure fashion.

Unleashing the power of boron: enhancing nitrogen reduction reaction through defective ReS2 monolayers.

Density functional theory (DFT) calculations were utilized to investigate the electrocatalytic potential of single boron (B) atom doping in defective ReS2 monolayers as an active site. Our investigation revealed that B-doped defective ReS2, containing S and S-Re-S defects, demonstrated remarkable conductivity, and emerged as an exceptionally active catalyst for nitrogen reduction reactions (NRR), exhibiting limiting potentials of 0.63 and 0.53 V, respectively. For both cases, we determined the potential by examining the hydrogenation of adsorbed N2* to N2H*. Although the competing hydrogen evolution reaction (HER) process appeared dominant in the S-Re-S defect case, its impact was minimal. The outstanding NRR performance can be ascribed to the robust chemical interactions between B and N atoms. The adsorption of N2 on B weakens the N-N bond, thereby facilitating the formation of NH3. Moreover, we verified the selectivity and stability of the catalysts for NRR. Our findings indicate that B-doped defective ReS2 monolayers hold considerable promise for electrocatalysis in a variety of applications.

Chemically Stable Low-Dimensional Electrides in Transition Metal-Rich Monochalcogenides: Theoretical and Experimental Explorations.

Electrides, which are ionic crystals composed of excess anionic electrons, are of great interest as an exotic material for fundamental research and practical applications in broad fields of science and technology. However, an inherent chemical instability under ambient conditions at room temperature has been a fatal drawback to be addressed. Here, we report that transition metal-rich monochalcogenides are an emerging class of low-dimensional electrides with excellent chemical and thermal stability in air and water at room temperature through a comprehensive exploration of theoretical prediction and experimental verification. We predict new two-dimensional (2D) electrides crystallized in hexagonal P3̅m1 and P63/mmc structures with strong localization of anionic electrons in a dumbbell shape at the tetrahedral cavity of the interlayer space, which are distinct from the anionic electrons localized at the octahedral cavity in the hexagonal R3̅m structure of the previous 2D [Ca2N]+·e- and [Y2C]2+·2e- electrides. We successfully synthesized the room-temperature stable [Ti2O]2+·2e-, [Ti2S]2+·2e-, [Zr2S]2+·2e-, and primary solid solution [Hf2SxSe1-x]2+·2e- electrides, showing no structural degradation in air and water. Among them, we found that the synthesized [Ti2S]2+·2e- and [Zr2S]2+·2e- electrides are crystallized in orthorhombic symmetry (Pnnm), showing the feature of a one-dimensional (1D) electride with an anionic electron chain, which has never been reported yet. In addition to the successful finding of new 1D and 2D electrides, we discuss the self-passivation effect-driven chemical stability and the role of anionic electrons in determining the physical properties of the newly discovered electrides.

Serial Intervals and Household Transmission of SARS-CoV-2 Omicron Variant, South Korea, 2021.

To clarify transmissibility of the severe acute respiratory syndrome coronavirus 2 Omicron variant, we determined serial intervals and secondary attack rates among household contacts in South Korea. Mean serial interval for 12 transmission pairs was 2.9 days, and secondary attack rate among 25 households was 50.0%, raising concern about a rapid surge in cases.

4-Hexylresorcinol Treatment before Degumming Increases the ß-Sheet Structure of Silk Sericin and BMP-2 Expression in RAW264.7 Cells.

Silk sericin is a degumming product used by the silk industry. The degumming process can affect the protein structure and molecular weight of silk sericin. The present study examined how pretreatment with 4-hexylresorcinol (4HR) affects the biomedical properties of silk sericin. Before the degumming process, silkworm cocoons were treated with 4HR solution. The protein structure of the final degumming product was evaluated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy. Untreated silk sericin (S) and silk sericin pretreated with 4HR (S+4HR) were added to RAW264.7 cells, and the expression of BMP-2 was determined. The bone-regenerating capacity of S+4HR was evaluated using the critical-sized rat calvarial defect model. Compared with S, S+4HR showed an increase in ß-sheet structures. Administration of S+4HR to RAW264.7 cells increased expression of BMP-2, mainly via the TLR-mediated signaling pathway. Bone volume, as measured by micro-computerized tomography, was significantly greater in the S+4HR group than in the S, gelatin alone, and unfilled control groups (p < 0.05 each). Expression of BMP-2 and runx2 in tissue specimens was significantly higher following treatment with S+4HR than with S (p < 0.05). Taken together, these findings show that 4HR pretreatment before the degumming process increased the ß-sheet structure of silk sericin, as well as inducing BMP-2 expression and bone regeneration ability.

Hypoxia-inducible factor 2α is a novel inhibitor of chondrocyte maturation.

Hypoxic environment is essential for chondrocyte maturation and longitudinal bone growth. Although hypoxia-inducible factor 1 alpha (Hif-1α) has been known as a key player for chondrocyte survival and function, the function of Hif-2α in cartilage is mechanistically and clinically relevant but remains unknown. Here we demonstrated that Hif-2α was a novel inhibitor of chondrocyte maturation through downregulation of Runx2 stability. Mechanistically, Hif-2α binding to Runx2 inhibited chondrocyte maturation by Runx2 degradation through disrupting Runx2/Cbfß complex formation. The Hif-2α-mediated-Runx2 degradation could be rescued by Cbfß transfection due to the increase of Runx2/Cbfß complex formation. Consistently, mesenchymal cells derived from Hif-2α heterozygous mice were more rapidly differentiated into hypertrophic chondrocytes than those of wild-type mice in a micromass culture system. Collectively, these findings demonstrate that Hif-2α is a novel inhibitor for chondrocyte maturation by disrupting Runx2/Cbfß complex formation and consequential regulatory activity.

Revealing well-defined cluster-supported bi-atom catalysts for enhanced CO2 electroreduction: a theoretical investigation.

It remains a great challenge to explore high-performance electrocatalysts for the CO2 reduction reaction (CO2RR) with high activity and selectivity. Herein, we employ first principles calculations to systematically investigate an emerging family of extended surface catalysts, bi-atom catalysts (BACs), in which bimetals anchored on graphitic carbon nitride (g-CN), for the CO2RR; and propose a novel framework to boost the CO2RR via incorporation with well-defined clusters. Among 28 BACs, five candidates (Cr2, CrFe, Mn2, MnFe and Fe2/g-CN) are first selected with efficient CO2 activation and favorability for CO2 reduction over H2 evolution. Fe2@g-CN is then served as a superior electrocatalyst for the CO2RR with low limiting potentials (UL) of -0.58 and -0.54 V towards C1 and C2 products. Intriguingly, the CO2RR performance of pure Fe2@g-CN could be controlled by tunable Fe atomic cluster integration. In particular, the presence of an Fe13 cluster could strengthen the CO2 adsorption, effectively deactivate H, and intriguingly break the adsorbate (CO* and CHO*) scaling relation to achieve the distinguished CO2RR with a lowered UL to -0.45 V for the C1 mechanism, which is attributed to the exceptional charge redistribution of bimetals modulated by Fe13. Our findings might open up possibilities for the rational design of BACs towards the CO2RR and other reactions.

Enhanced performance of Mo2P monolayer as lithium-ion battery anode materials by carbon and nitrogen doping: a first principles study.

By means of density functional theory (DFT) computations, we explored the potential of carbon- and nitrogen-doped Mo2P (CMP and NMP) layered materials as the representative of transition metal phosphides (TMPs) for the development of lithium-ion battery (LIB) anode materials, paying special attention to the synergistic effects of the dopants. Both CMP and NMP have exceptional stabilities and excellent electronic conductivity, and a high theoretical maximum storage capacity of ∼ 486 mA h g-1. Li-ion diffusion barriers on the two-dimensional (2D) CMP and NMP surfaces are extremely low (∼0.036 eV), and it is expected that on these 2D layers Li can diffuse 104 times faster than that on MoS2 and graphene at room temperature, and both monolayers have relatively low average open-circuit voltage (0.38 and 0.4 eV). All these exceptional properties make CMP and NMP monolayers as promising candidates for high-performance LIB anode materials, which also demonstrates that simple doping is an effective strategy to enhance the performance of anode materials in rechargeable batteries.

Effects of 4-Hexylresorcinol on Craniofacial Growth in Rats.

4-Hexylresorcinol (4HR) has been used as a food additive, however, it has been recently demonstrated as a Class I histone deacetylase inhibitor (HDACi). Unlike other HDACi, 4HR can be taken through foods. Unfortunately, some HDACi have an influence on craniofacial growth, therefore, the purpose of this study was to evaluate the effects of 4HR on craniofacial growth. Saos-2 cells (osteoblast-like cells) were used for the evaluation of HDACi and its associated activities after 4HR administration. For the evaluation of craniofacial growth, 12.8 mg/kg of 4HR was administered weekly to 4 week old rats (male: 10, female: 10) for 12 weeks. Ten rats were used for untreated control (males: 5, females: 5). Body weight was recorded every week. Serum and head samples were collected at 12 weeks after initial administration. Craniofacial growth was evaluated by micro-computerized tomography. Serum was used for ELISA (testosterone and estrogen) and immunoprecipitation high-performance liquid chromatography (IP-HPLC). The administration of 4HR (1-100 µM) showed significant HDACi activity (p < 0.05). Body weight was significantly different in male rats (p < 0.05), and mandibular size was significantly smaller in 4HR-treated male rats with reduced testosterone levels. However, the mandibular size was significantly higher in 4HR treated female rats with increased growth hormone levels. In conclusion, 4HR had HDACi activity in Saos-2 cells. The administration of 4HR on growing rats showed different responses in body weight and mandibular size between sexes.

The Effect of Buccal Fat Pad Graft in the Palatoplasty and the Risk Factor of Postoperative Palatal Fistula.

PURPOSE: The aim of this study was to evaluate the effect of buccal fat pad (BFP) in the palatoplasty and to investigate the risk factors associated with postoperative palatal fistula formation. MATERIALS AND METHODS: Sixty-five cleft palate patients were enrolled for this study. Clinical data regarding sex, age, type of cleft, surgical technique, the ratio of cleft width, and BFP graft were collected. The ratio of cleft width was measured and calculated using preoperative clinical photographs. In 36 patients, the BFP was harvested and grafted on the cleft palate to prevent palatal fistula formation. The patients were followed up, the incidence of fistula formation was investigated, and the risk factors related with the fistula were evaluated. RESULTS: Four patients had postoperative palatal fistula and were not BFP grafted during operation. The BFP graft and ratio of cleft width are significant factors in palatal fistula formation (P = .035, .003). There was a significant difference in the ratio of cleft width between the normal and fistula groups (P = .006). In the logistic regression analysis, there was significant association between high ratio of cleft width and palatal fistula formation in the no BFP group (odds ratio; 11.15, P = .036). CONCLUSIONS: The ratio of cleft width and BFP graft was a significant factor in palatal fistula formation. The BFP graft is a reliable procedure to prevent palatal fistula formation and increase the success of palatoplasty.

The Administration of 4-Hexylresorcinol Accelerates Orthodontic Tooth Movement and Increases the Expression Level of Bone Turnover Markers in Ovariectomized Rats.

Surgical methods for accelerating orthodontic tooth movement are limited by possible damage to the tooth root and patient discomfort. 4-Hexylresorcinol (4HR) has been shown to increase bone remodeling and may potentially facilitate tooth movement. This study investigated the (1) effect of 4HR administration on osteoblast-like cells and (2) effect of 4HR administration on tooth movement in ovariectomized rats. Saos-2 cells were treated with either 4HR or solvent (control). Protein expression levels were investigated 2, 8, and 24 h after treatment. Thirty ovariectomized Sprague-Dawley rats were divided into two experimental groups (A and B) and one control group. After installation of an orthodontic tooth movement device, groups A and B received subcutaneous weekly injections of 4HR (1.28 and 128 mg/kg). Micro-computerized tomography and histological analyses were performed after 2 weeks of tooth movement. The application of 4HR elevated expression of osteogenic markers in Saos-2 cells. Movement of the first molars was significantly greater in rats administered 4HR. Furthermore, the expression of bone morphogenic protein-2, receptor activator of nuclear factor kappa-B ligand, osteocalcin, and tartrate-resistant acid phosphatase were increased after 4HR administration. 4HR application demonstrated increased expression of osteogenic markers in Saos-2 cells and accelerated orthodontic tooth movement in rats.

Increased Level of Vascular Endothelial Growth Factors by 4-hexylresorcinol is Mediated by Transforming Growth Factor-ß1 and Accelerates Capillary Regeneration in the Burns in Diabetic Animals.

4-Hexyl resorcinol (4HR) is an organic compound and has been used in skin care application. 4HR is an M2-type macrophage activator and elevates vascular endothelial growth factor (VEGF) expression via the hypoxia-inducible factor (HIF)-independent pathway. As endothelial cells are important in wound healing, the human umbilical vein endothelial cells (HUVECs) were treated with 4HR, and changes in VEGF-A, -C, and transforming growth factor-ß1 (TGF-ß1) expression were investigated. The administration of 4HR increased the expression level of VEGF-A, -C, and TGF-ß1. The application of TGF-ß1 protein also increased the expression level of VEGF-A and -C. Knockdown with small interfering RNA (siRNA) targeting to TGF-ß1 and the selective chemical inhibition (A83-01) to ALK5 confirmed the involvement of the TGF-ß signaling pathway in the 4-HR-mediated VEGFs expression. 4HR application in a burn model of diabetic rats demonstrated an increased level of angiogenic proteins with wound healing. Compared to sericin application, the 4HR application group showed more prominent capillary regeneration. Collectively, 4HR activated TGF-ß1/ALK5/VEGFs signaling in endothelial cells and induced vascular regeneration and remodeling for wound healing.

Botulinum Toxin Injection to Treat Masticatory Movement Disorder Corrected Mandibular Asymmetry in a Growing Patient.

An 8-year-old girl with masticatory movement disorder received botulinum toxin-A (BTX-A) injection and orthodontic treatment. She showed facial asymmetry with right masseter muscle hyperplasia. After BTX-A injection combined with orthodontic treatment, the transverse discrepancy between right and left maxillary dentition completely corrected. Cone-beam computed tomography images revealed that the height of the left mandibular ramus had increased by 2.3 mm, considerably more than on the right side, the discrepancy in mandibular ramus height between the left and the right decreased dramatically. In a short period, BTX-A injection combined with orthodontic treatment corrected a mandibular movement disorder with asymmetric mandibular growth in a growing patient.

Custom Implant for Reconstruction of Mandibular Continuity Defect.

PURPOSE: The purpose of this study was to compare the daily food intake rate and the rate of screw loosening between 2 groups of rabbits with mandibular continuity defects: custom implant (CI) group and 5-hole mini-plate group. MATERIALS AND METHODS: Two types of cylindrical implants were printed, and their physical strength was compared. In this study using rabbits, 1 group (n = 5) received a CI for the reconstruction of a mandibular continuity defect (CI group) and the other group (n = 5) received a 5-hole mini-plate without a bone graft (reconstruction plate [RP] group). After reconstruction, the daily food intake rate and the rate of screw loosening were examined postoperatively. Histologic examination in the CI group was performed 3 months after the operation. RESULTS: The design that mimicked the mandible showed greater physical strength. The amount of time required to achieve 50% recovery was shorter in the CI group than in the RP group (P = .011). The total number of loosened screws in the CI group was lower than that in the RP group at 3 months postoperatively (P = .008). New bone formation in the porous CI was evident in the CI group. CONCLUSIONS: Rabbits with mandibular continuity defects treated with CIs for reconstruction showed faster recovery of the daily food intake rate and fewer loosened screws than those treated with a 5-hole mini-plate without bone graft.

Porcine Bone Incorporated With 4-Hexylresorcinol Increases New Bone Formation by Suppression of the Nuclear Factor Kappa B Signaling Pathway.

OBJECTIVE: The objectives of this study were to evaluate the suppression of the nuclear factor kappa B (NF-kB) pathway by 4-hexylresorcinol (4HR), which was activated by tumor necrosis factor-α (TNF-α) in osteoblasts, and new bone formation by 4HR-incorporated porcine bone in an animal model. STUDY DESIGN: For the confirmation of successful incorporation of 4HR into porcine bone, scanning electron microscopy (SEM) and Fourier transform-infrared (FT-IR) analysis were performed. High performance liquid chromatography was performed for the analysis of the 4HR release profile from porcine bone. MC 3T3-E1 cells were used for the analysis of the NF-kB signaling pathway activation by western blotting and real-time reverse transcriptase polymerase chain reaction. New bone formation and the analysis of marker protein expression were studied in a rat calvarial critical-sized defect model. RESULTS: Both SEM and FT-IR analysis demonstrated successful incorporation of 4HR into porcine bone. Approximately 30% of 4HR was steadily released from porcine bone for 18 days. 4HR suppressed the NF-kB signaling pathway, which was activated by TNF-α application in MC 3T3-E1 cells. Histological analysis revealed that porcine bone particles with incorporated 4HR showed significantly greater new bone formation than those without 4HR at 4 and 8 weeks after operation (P < 0.05). The expression intensities of alkaline phosphatase, osteoprotegerin, and osteocalcin were also higher in the 4HR-incorporated group. CONCLUSION: The application of 4HR suppressed the NF-kB signaling pathway in osteoblasts and 4HR-containing porcine bone particles promoted new bone formation in a rat calvarial defect model.

Mandibular Reconstruction Using a Customized Three-Dimensional Titanium Implant Applied on the Lingual Surface of the Mandible.

A patient had a right mandibular defect due to resection of an ameloblastoma. Previously, the defect had been reconstructed by an iliac bone graft, and subsequently, a titanium mesh with xenograft was used. However, it was not successfully reconstructed. For the recovery of mandible continuity and rehabilitation of jaw movement, we manufactured a customized 3-dimensional titanium implant by computer-aided design and manufacturing and electron beam melting technology. This implant was designed to have a porous body structure and lingual plate. The customized implant was accurately inserted in the bony defect. As a result, the patient showed a normal range of mouth opening and jaw movement. New bone migration was observed in the porous structure of the implant. Although there was a slight plate exposure and lack of alveolar bone formation, the customized 3D titanium implant successfully reconstructed the mandibular discontinuous defect and recovered jaw movement.