3D Pathways Enabling Highly-Efficient Lithium Reservoir for Fast-Charging Batteries

Enhancing the mobility of lithium-ions (Li+ ) through surface engineering is one of major challenges facing fast-charging lithium-ion batteries (LIBs). In case of demanding charging conditions, the use of a conventional artificial graphite (AG) anode leads to an increase in operating temperature and the formation of lithium dendrites on the anode surface. In this study, a biphasic zeolitic imidazolate framework (ZIF)-AG anode, designed strategically and coated with a mesoporous material, is verified to improve the pathways of Li+ and electrons under a high charging current density. In particular, the graphite surface is treated with a coating of a ZIF-8-derived carbon nanoparticles, which addresses sufficient surface porosity, enabling this material to serve as an electrolyte reservoir and facilitate Li+ intercalation. Moreover, the augmentation in specific surface area proves advantageous in reducing the overpotential for interfacial charge transfer reactions. In practical terms, employing a full-cell with the biphasic ZIF-AG anode results in a shorter charging time and improved cycling performance, demonstrating no evidence of Li plating during 300 cycles under 3.0 C-charging and 1.0 C-discharging. The research endeavors to contribute to the progress of anode materials by enhancing their charging capability, aligning with the increasing requirements of the electric vehicle applications.

Dry-Electrode All-Solid-State Batteries Fortified with a Moisture Absorbent

For realizing all-solid-state batteries (ASSBs), it is highly desirable to develop a robust solid electrolyte (SE) that has exceptional ionic conductivity and electrochemical stability at room temperature. While argyrodite-type Li6PS5Cl (LPSCl) SE has garnered attention for its relatively high ionic conductivity (∼3.19 × 10-3 S cm-1), it tends to emit hydrogen sulfide (H2S) in the presence of moisture, which can hinder the performance of ASSBs. To address this issue, researchers are exploring approaches that promote structural stability and moisture resistance through elemental doping or substitution. Herein, we suggest using zeolite imidazolate framework-8 as a moisture absorbent in LPSCl without modifying the structure of the SE or the electrode configuration. By incorporating highly ordered porous materials, we demonstrate that ASSBs configured with LPSCl SE display stable cyclability due to effective and long-lasting moisture absorption. This approach not only improves the overall quality of ASSBs but also lays the foundation for developing a moisture-resistant sulfide electrolyte.

Bi-Morphological Form of SiO2 on a Separator for Modulating Li-Ion Solvation and Self-Scavenging of Li Dendrites in Li Metal Batteries

The lithium (Li) metal anode is highly desirable for high-energy density batteries. During prolonged Li plating-stripping, however, dendritic Li formation and growth are probabilistically high, allowing physical contact between the two electrodes, which results in a cell short-circuit. Engineering the separator is a promising and facile way to suppress dendritic growth. When a conventional coating approach is applied, it usually sacrifices the bare separator structure and severely increases the thickness, ultimately decreasing the volumetric density. Herein, we introduce dielectric silicon oxide with the feature of bi-morphological form, i.e., backbone-covered and backbone-anchored, onto the conventional polyethylene separator without any volumetric change. These functionally vary the Li⁺ transference number and the ionic conductivity so as to modulate Li-ion solvation and self-scavenging of Li dendrites. The proposed separator paves the way to maximizing the full cell performance of Li/NCM622 toward practical application.

Porous carbon architectures with different dimensionalities for lithium metal storage

Lithium metal batteries have recently gained tremendous attention owing to their high energy capacity compared to other rechargeable batteries. Nevertheless, lithium (Li) dendritic growth causes low Coulombic efficiency, thermal runaway, and safety issues, all of which hinder the practical application of Li metal as an anodic material. In this review, the failure mechanisms of Li metal anode are described according to its infinite volume changes, unstable solid electrolyte interphase, and Li dendritic growth. The fundamental models that describe the Li deposition and dendritic growth, such as the thermodynamic, electrodeposition kinetics, and internal stress models are summarized. From these considerations, porous carbon-based frameworks have emerged as a promising strategy to resolve these issues. Thus, the main principles of utilizing these materials as a Li metal host are discussed. Finally, we also focus on the recent progress on utilizing one-, two-, and three-dimensional carbon-based frameworks and their composites to highlight the future outlook of these materials.

Nanoarchitectonics of the cathode to improve the reversibility of Li-O2 batteries

The strategic design of the cathode is a critical feature for high-performance and long-lasting reversibility of an energy storage system. In particular, the round-trip efficiency and cycling performance of nonaqueous lithium-oxygen batteries are governed by minimizing the discharge products, such as Li₂O and Li₂O₂. Recently, a metal-organic framework has been directly pyrolyzed into a carbon frame with controllable pore volume and size. Furthermore, selective metallic catalysts can also be obtained by adjusting metal ions for outstanding electrochemical reactions. In this study, various bimetallic zeolitic imidazolate framework (ZIF)-derived carbons were designed by varying the ratio of Zn to Co ions. Moreover, carbon nanotubes (CNTs) are added to improve the electrical conductivity further, ultimately leading to better electrochemical stability in the cathode. As a result, the optimized bimetallic ZIF-carbon/CNT composite exhibits a high discharge capacity of 16,000 mAh·g^-1, with a stable cycling performance of up to 137 cycles. This feature is also beneficial for lowering the overpotential of the cathode during cycling, even at the high current density of 2,000 mA·g^-1.

Strategic Approaches to the Dendritic Growth and Interfacial Reaction of Lithium Metal Anode

Utilization of lithium (Li) metal anode is highly desirable for achieving high energy density batteries. Even so, the unavoidable features of Li dendritic growth and inactive Li are still the main factors that hinder its practical application. During plating and stripping, the solid electrolyte interphase (SEI) layer can provide passivation, playing an important role in preventing direct contact between the electrolyte and the electrode in Li metal batteries. Because of complexities of the electrolyte chemical and electrochemical reactions, the various formation mechanisms for the SEI are still not well understood. What we do know is that a strategic artificial SEI achieved through additives electrolyte can suppress the Li dendrites. Otherwise, the dendrites keep generating an abundance of irreversible Li, resulting in severe capacity loss, internal short-circuiting, and cell failure. In this minireview, we focus on the phenomenon of dendritic Li-growth and provide a brief overview of SEI formation. We finally provide some clear insights and perspectives toward practical application of Li metal batteries.

Patchable and Implantable 2D Nanogenerator

With the development of technology, electronic devices are becoming more miniaturized and multifunctional. With the development of small electronic devices, they are changing from the conventional accessory type, which is portable, to the patchable type, which can be attached to a person's apparel or body, and the eatable/implantable type, which can be directly implanted into the human body. In this regard, it is necessary to address various technical issues, such as high-capacity/high-efficiency small-sized battery technology, component miniaturization, low power technology, flexible technology, and smart sensing technology. In addition, there is a demand for self-powered wireless systems in particular devices. A piezoelectric/triboelectric nanogenerator (PENG/TENG) can generate electric energy from small amounts of mechanical energy such as from blood flow and heartbeats in the human body as well as human movement, so it is expected that it will enable the development of self-powered wireless systems. Due to their unique properties, such as flexibility, transparency, mechanical stability, and nontoxicity, 2D materials are optimal materials for the development of implantable and patchable self-powered nanodevices in the human body. In this Review, the studies related to patchable and implantable devices for the human body using PENGs/TENGs based on 2D materials are discussed.

Biomolecular Piezoelectric Materials: From Amino Acids to Living Tissues

Biomolecular piezoelectric materials are considered a strong candidate material for biomedical applications due to their robust piezoelectricity, biocompatibility, and low dielectric property. The electric field has been found to affect tissue development and regeneration, and the piezoelectric properties of biological materials in the human body are known to provide electric fields by pressure. Therefore, great attention has been paid to the understanding of piezoelectricity in biological tissues and its building blocks. The aim herein is to describe the principle of piezoelectricity in biological materials from the very basic building blocks (i.e., amino acids, peptides, proteins, etc.) to highly organized tissues (i.e., bones, skin, etc.). Research progress on the piezoelectricity within various biological materials is summarized, including amino acids, peptides, proteins, and tissues. The mechanisms and origin of piezoelectricity within various biological materials are also covered.

Everlasting Living and Breathing Gyroid 3D Network in Si@SiOx/C Nanoarchitecture for Lithium Ion Battery

Silicon-based materials are the most promising candidates to surpass the capacity limitation of conventional graphite anode for lithium ion batteries. Unfortunately, Si-based materials suffer from poor cycling performance and dimensional instability induced by the large volume changes during cycling. To resolve such problems, nanostructured silicon-based materials with delicately controlled microstructure and interfaces have been intensively investigated. Nevertheless, they still face problems related to their high synthetic cost and their limited electrochemical properties and thermal stability. To overcome these drawbacks, we demonstrate the strategic design and synthesis of a gyroid three-dimensional network in a Si@SiO_x/C nanoarchitecture (3D-Si@SiO_x/C) with synergetic interaction between the computational prediction and the synthetic optimization. This 3D-Si@SiO_x/C exhibits not only excellent electrochemical performance due to its structural stability and superior ion/electron transport but also enhanced thermal stability due to the presence of carbon, which was formed by a cost-effective one-pot synthetic route. We believe that our rationally designed 3D-Si@SiO_x/C will lead to the development of anode materials for the next-generation lithium ion batteries.

Point-Defect-Passivated MoS2 Nanosheet-Based High Performance Piezoelectric Nanogenerator

In this work, a sulfur (S) vacancy passivated monolayer MoS₂ piezoelectric nanogenerator (PNG) is demonstrated, and its properties before and after S treatment are compared to investigate the effect of passivating S vacancy. The S vacancies are effectively passivated by using the S treatment process on the pristine MoS₂ surface. The S vacancy site has a tendency to covalently bond with S functional groups; therefore, by capturing free electrons, a S atom will form a chemisorbed bond with the S vacancy site of MoS₂ . S treatment reduces the charge-carrier density of the monolayer MoS₂ surface, thus the screening effect of piezoelectric polarization charges by free carrier is significantly prevented. As a result, the output peak current and voltage of the S-treated monolayer MoS₂ nanosheet PNG are increased by more than 3 times (100 pA) and 2 times (22 mV), respectively. Further, the S treatment increases the maximum power by almost 10 times. The results suggest that S treatment can reduce free-charge carrier by sulfur S passivation and efficiently prevent the screening effect. Thus, the piezoelectric output peaks of current, voltage, and maximum power are dramatically increased, as compared with the pristine MoS₂ .

Point-Defect-Passivated MoS2 Nanosheet-Based High Performance Piezoelectric Nanogenerator

In this work, a sulfur (S) vacancy passivated monolayer MoS₂ piezoelectric nanogenerator (PNG) is demonstrated, and its properties before and after S treatment are compared to investigate the effect of passivating S vacancy. The S vacancies are effectively passivated by using the S treatment process on the pristine MoS₂ surface. The S vacancy site has a tendency to covalently bond with S functional groups; therefore, by capturing free electrons, a S atom will form a chemisorbed bond with the S vacancy site of MoS₂ . S treatment reduces the charge-carrier density of the monolayer MoS₂ surface, thus the screening effect of piezoelectric polarization charges by free carrier is significantly prevented. As a result, the output peak current and voltage of the S-treated monolayer MoS₂ nanosheet PNG are increased by more than 3 times (100 pA) and 2 times (22 mV), respectively. Further, the S treatment increases the maximum power by almost 10 times. The results suggest that S treatment can reduce free-charge carrier by sulfur S passivation and efficiently prevent the screening effect. Thus, the piezoelectric output peaks of current, voltage, and maximum power are dramatically increased, as compared with the pristine MoS₂ .

Reliable Piezoelectricity in Bilayer WSe2 for Piezoelectric Nanogenerators

Recently, piezoelectricity has been observed in 2D atomically thin materials, such as hexagonal-boron nitride, graphene, and transition metal dichalcogenides (TMDs). Specifically, exfoliated monolayer MoS₂ exhibits a high piezoelectricity that is comparable to that of traditional piezoelectric materials. However, monolayer TMD materials are not regarded as suitable for actual piezoelectric devices due to their insufficient mechanical durability for sustained operation while Bernal-stacked bilayer TMD materials lose noncentrosymmetry and consequently piezoelectricity. Here, it is shown that WSe₂ bilayers fabricated via turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a mechanically exfoliated WSe₂ bilayer with Bernal stacking. Turbostratic stacking refers to the transfer of each chemical vapor deposition (CVD)-grown WSe₂ monolayer to allow for an increase in degrees of freedom in the bilayer symmetry, leading to noncentrosymmetry in the bilayers. In contrast, CVD-grown WSe₂ bilayers exhibit very weak piezoelectricity because of the energetics and crystallographic orientation. The flexible piezoelectric WSe₂ bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources, in contrast to monolayer WSe₂ for which the device performance becomes degraded above a strain of 0.63%.

Noise and sensitivity characteristics of solid-state nanopores with a boron nitride 2-D membrane on a pyrex substrate

We have fabricated highly sensitive and low noise solid-state nanopores with multiple layers of boron nitride (BN) membranes transferred onto a pyrex substrate. Both the dielectric and flicker noise of the device, which have been described as one of the bottlenecks to making highly sensitive 2-D membrane nanopore devices, have been reduced as follows. Firstly, a pyrex substrate with a low dielectric constant (εr = 4.7-5.1) and low dielectric loss (D < 0.001) is used instead of a Si substrate to reduce the dielectric noise of the device. Secondly, flicker noise is minimized by employing a 100 nm thick SiNx supporting layer with a small opening (less than 100 nm) for BN membrane transfer to enhance the mechanical stability. The flicker noise is further reduced by transferring multiple layers of BN instead of a single layer of BN. The resulting multi-layered BN device shows significant reduction of dielectric and 1/f noise as compared to the devices with a single layer of the BN and Si substrate. Furthermore, we demonstrate dsDNA translocations with a high signal to noise ratio around 50 at 100 and 10 kHz bandwidths.

Surface energy and wettability of van der Waals structures

The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability.

Formation of hexagonal boron nitride by metal atomic vacancy-assisted B-N molecular diffusion

Because of the low solubility of N atoms in metals, hexagonal boron nitride (h-BN) growth has explained by surface reaction on metal rather than by penetration/precipitation of B and N atoms in metal. Here, we present an impressive pathway of h-BN formation at the interface between Ni and oxide substrate based on B-N molecular diffusion into Ni through individual atomic vacancies. First-principles calculations confirmed the formation energies of the h-BN layers on and under the metal and the probability of B-N molecular diffusion in metal. The interface growth behavior depends on the species of metal catalysts, and these simulation results well support experimental results.

Chondrogenic potentials of human synovium-derived cells sorted by specific surface markers

OBJECTIVE

We aimed to evaluate expression levels of nine candidate surface markers for chondrogenic potential in human synovial cells and to determine whether cell pellets positively sorted by each specific marker would have valuable chondrogenic potential.

METHODS

The expression levels of the selected nine leading surface markers in synovial cells from knee joints in 15 patients with primary knee osteoarthritis were evaluated at the stage of isolation and after cultivation using flow cytometry. We obtained positive and negative cells for each surface marker using a magnetically activated cell sorting method and compared chondrogenic potentials between the positive and the negative cell pellets.

RESULTS

CD29, CD44, CD73, and CD90 were expressed on the most synovial cells at the isolation stage and on almost all cells at stage of P0 and P1. CD133 was rarely expressed at any stages of the evaluated cells. CD166 was expressed in 7.1% of cells at the isolation stage on average, but this expression increased after cell passages. The expressions of CD10 and CD105 also increased after cell passages while the expression of CD49a made no significant difference at progressive stages of isolation and passage. Comparison of chondrogenic potentials between positive and negative cell pellets for each marker revealed that only CD105- and CD166-positive cell pellets showed better chondrogenic potentials (type II collagen gene expression, cartilage matrix formation, and GAG expression) than the corresponding negative cell pellets.

CONCLUSION

Our study suggests that CD105 and CD166 would be valuable surface markers associated with chondrogenic potential; thus, CD105- and CD166-enriched cells derived from human synovium would be practical and valuable sources for cartilage regeneration.

Ridge formation and removal via annealing in exfoliated graphene

It is well known that graphene is a very promising material due to its excellent physical, chemical, and thermal properties. Previously, ridges in graphene on a substrate were found in epitaxial graphene on a SiC substrate. It was found in this study that ridges can be made on a graphene layer via mechanical exfoliation on a sapphire substrate, and that ridges can be created or removed through heating and cooling. Due to the difference of the thermal-expansion coefficients of the substrate and graphene, it can be said that thermal cycling causes compressive strain, which is released by forming ridges. Annealing was carried out in a vacuum chamber within the pressure range of 10(-3)-10(-6) Torr and at 900-1100 degrees C. To analyze the shapes and mechanical properties of the ridges, Raman spectroscopy and AFM measurement were performed. It was found that the ridges can be extended by defect as a nucleation center, and the graphene layer can be folded along the preexisting ridge during heating and cooling.

Prognostic Significance of β-catenin in Colorectal Cancer with Liver Metastasis

AIMS

A decreased expression of beta-catenin has been known to be associated with tumour metastasis. The prognostic value of beta-catenin expression in colorectal cancer (CRC) patients with liver metastasis was evaluated.

MATERIALS AND METHODS

Seventy patients who underwent curative resection for CRC with liver metastasis were included. Tissue samples from normal colon mucosa, primary CRC and metastatic liver lesions were prepared in tissue microarrays, and were stained by immunohistochemistry with beta-catenin antibody. The beta-catenin expression of primary CRC tissues and metastatic liver tissues was analysed.

RESULTS

A high expression of beta-catenin (score > 6) was observed in 42.0% and 21.9% of primary colorectal tissues and metastatic liver tissues, respectively. The beta-catenin expression in metastatic liver tissues was significantly lower than in primary CRC tissues (P = 0.022). The patients were classified into two groups according to the difference in the beta-catenin expression score between the primary CRC and the liver metastasis. Group A was defined as patients showing a remarkably decreased expression of beta-catenin in their metastatic liver tissue and group B was defined as patients showing a maintained or increased beta-catenin expression in their metastatic liver tissue in comparison with their primary CRC. The overall survival and disease-free survival rates were better in group B than in group A, and this was statistically significant (P = 0.02, P = 0.002).

CONCLUSION

The decreased expression of beta-catenin in a metastatic liver lesion may be a poor prognostic marker in CRC with liver metastasis and further investigation is necessary.

Clinical Significance of Peripheral Blood CEA mRNA Expression in Gastric Cancer Patients Underwent Curative Resection

PURPOSE

Recent advances in molecular technology have made it possible to detect small numbers of circulating tumor cells in the peripheral blood or bone marrow. Carcinoembryonic antigen (CEA) is an oncofetal antigen that is expressed in epithelial tumor cells. CEA mRNA may be a reliable marker for the detection of tumor cells in the peripheral blood of patients with epithelial cancer.

MATERIALS AND METHODS

We analyzed the peripheral blood of 46 patients with gastric cancer who had undergone curative resection. The presence of CEA mRNA was serially monitored using RT-PCR (Preop, Post op 15 day, 2 months (m), 4 m, 6 m, 8 m, 10 m, 12 m). The clinical characteristics, serum CEA level and immunohistochemical staining of tumor tissue were also evaluated. Patients were followed up for 6 to 12 months.

RESULTS

There was no significant relationship seen between CEA mRNA RT-PCR positivity in the peripheral blood and sex, stage, serum CEA level or immunohistochemical staining for CEA antigen, During follow up,eight patients experienced recurrence; were positve for CEA mRNA RT-PCR recurrence was seen in 66.7% (6/9) of the patients who before clinical recurrence as compared to 5.4% (2/37) of patients who were negative (p=0.0002). Serial changes of CEA mRNA RT-PCR correlated with clinical recurrence; 100% in the positively converted group (3/3), 0% in the negatively converted group(0/18), 50% in all positive group (3/6) and 10.5% in all negative group (2/19) experienced recurrence, respectively.

CONCLUSION

RT-PCR analysis of CEA mRNA in the peripheral blood seems to be a promising tool for the early detection of micrometastatic circulating tumor cells in gastric cancer patients and may be useful in determining patients at high risk for recurrence. However, definitive correlation with recurrence certainly requires a longer follow up duration in further studies.

beta-catenin expression and mutational analysis in renal cell carcinomas

beta-Catenin acts as a downstream transcriptional activator of the Wingless-Wnt signaling pathway. The beta-catenin-Tcf complex transactivates the downstream genes that regulate cell proliferation or inhibit apoptosis. The activation of this pathway through stabilization of beta-catenin is caused either by inactivating mutations of adenomatous polyposis coli (APC) tumor suppressor gene or by activating mutations in beta-catenin exon 3. To determine whether the abnormal expression and activating mutations in exon 3 of the beta-catenin gene are implicated in renal cell carcinogenesis, 52 renal cell carcinomas (RCC) were analyzed by immunohistochemistry, polymerase chain reaction-single-strand conformational polymorphism analysis (PCR-SSCP), and direct DNA sequencing. Immunohistochemically, all cases, as well as normal kidneys, showed membranous and/or cytoplasmic staining patterns without nuclear localization. However, the cytoplasmic accumulations of beta-catenin were observed in five (22.7%) of 22 cases of conventional (clear cell) renal carcinoma, but not in papillary or chromophobe renal carcinomas. The beta-catenin mutation was identified in only one case of conventional renal carcinoma and was a single-base missense mutation on codon 61, leading to substitution of glutamine by arginine. In conclusion, this study demonstrates that beta-catenin mutations are a relatively rare event in RCC and that cytoplasmic accumulations of beta-catenin protein are found only in conventional (clear cell) renal carcinomas. These data suggest that the activation of the beta-catenin signaling pathway may partly play a role in the development of conventional RCC.

Characterization of mouse integrin alpha3 subunit gene

Integrin alpha3beta1 (VLA-3) is an adhesion receptor for extracellular matrix proteins including various isoforms of laminin. We have isolated mouse genomic clones encoding the integrin alpha3 subunit and deduced the exon/intron organization. The mouse integrin alpha3 subunit gene is encoded by 26 exons spanning 40 kb. The exon/intron structure of the integrin alpha3 subunit gene resembles that of the integrin alpha6 subunit gene, but differs somewhat from those of other members of the integrin family. We have demonstrated that the cytoplasmic domain splicing variants of the alpha3 subunits (alpha3A and alpha3B) are generated by alternative exon usage. We also cloned the 5'-flanking region and performed a preliminary analysis of its promoter activity in various tumor cell lines with different degrees of integrin alpha3 expression. Following transfection, activity in the luciferase assay was found to be roughly correlated with the expression level of integrin alpha3 as measured by flow cytometry. Furthermore, the luciferase assay was performed with normal and SV-40- or polyoma virus-transformed fibroblasts. In mouse, human, and hamster fibroblasts, higher levels of luciferase expression were observed in transformed cells than in normal cells. This result is consistent with our previous finding that integrin alpha3 expression at both the protein and mRNA levels is enhanced upon oncogenic transformation of fibroblasts by tumor viruses.