Boosting the reaction kinetics in aprotic lithium-carbon dioxide batteries with unconventional phase metal nanomaterials.

Given the high energy density and eco-friendly characteristics, lithium-carbon dioxide (Li-CO2) batteries have been considered to be a next-generation energy technology to promote carbon neutral and space exploration. However, Li-CO2 batteries suffer from sluggish reaction kinetics, causing large overpotential and poor energy efficiency. Here, we observe enhanced reaction kinetics in aprotic Li-CO2 batteries with unconventional phase 4H/face-centered cubic (fcc) iridium (Ir) nanostructures grown on gold template. Significantly, 4H/fcc Ir exhibits superior electrochemical performance over fcc Ir in facilitating the round-trip reaction kinetics of Li+-mediated CO2 reduction and evolution, achieving a low charge plateau below 3.61 V and high energy efficiency of 83.8%. Ex situ/in situ studies and theoretical calculations reveal that the boosted reaction kinetics arises from the highly reversible generation of amorphous/low-crystalline discharge products on 4H/fcc Ir via the Ir-O coupling. The demonstration of flexible Li-CO2 pouch cells with 4H/fcc Ir suggests the feasibility of using unconventional phase nanomaterials in practical scenarios.

In Situ Characterizations of the Dynamics of Cathode Electrolyte Interfaces at Different Current Densities.

LiNi0.8Mn0.1Co0.1O2 with high nickel content plays a critical role in enabling lithium metal batteries (LMBs) to achieve high specific energy density, making them a prominent choice for electric vehicles (EVs). However, ensuring the long-term cycling stability of the cathode electrolyte interfaces (CEIs), particularly at fast-charge conditions, remains an unsolved challenge. The decay mechanism associated with CEIs and electrolytes in LMB at high current densities is still not fully understood. To address this issue, in situ Fourier transform infrared (FTIR) is employed to observe the dynamic process of formation/disappearance/regeneration of CEIs during charge and discharge cycles. These dynamic processes further exacerbate the instability of CEIs as current density increases, leading to rupture and dissolution of CEIs and subsequent deterioration in battery performance because of continuous electrolyte reactions. Additionally, the dynamic changes occurring within individual components of CEIs at different cycling stages and various current densities are also discussed. The results demonstrate that excellent capacity retention at small current density is attributed to enrichment of inorganic compounds (Li2CO3, LiF, etc.) and rendering better stability and smaller expansion of CEIs. The key to achieving excellent electrochemical performance at high current densities lies on protecting CEIs, mainly inorganic components.

Porous Mo3 P/Mo Nanorods as Efficient Mott-Schottky Cathode Catalysts for Low Polarization Li-CO2 Battery.

Li-CO2 battery with high energy density has aroused great interest recently, large-scale applications are hindered by the limited cathode catalysis performance and execrably cycle performance. Herein, Mo3 P/Mo Mott-Schottky heterojunction nanorod electrocatalyst with abundant porous structure is fabricated and served as cathodes for Li-CO2 batteries. The Mo3 P/Mo cathodes exhibit ultra-high discharge specific capacity of 10 577 mAh g-1 , low polarization voltage of 0.15 V, and high energy efficiency of up to 94.7%. Mott-Schottky heterojunction formed by Mo and Mo3 P drives electron transfer and optimizes the surface electronic structure, which is beneficial to accelerate the interface reaction kinetics. Distinctively, during the discharge process, the C2 O4 2- intermediates combine with Mo atoms to form a stable Mo-O coupling bridge on the catalyst surface, which effectively facilitate the formation and stabilization of Li2 C2 O4 products. In addition, the construction of the Mo-O coupling bridge between the Mott-Schottky heterojunction and Li2 C2 O4 promotes the reversible formation and decomposition of discharge products and optimizes the polarization performance of the Li-CO2 battery. This work provides another pathway for the development of heterostructure engineering electrocatalysts for high-performance Li-CO2 batteries.

Flexible Li-CO2 Batteries with Boosted Reaction Kinetics and Cyclelife Enabled by Heterostructured Mo3 N2 @TiN Cathode and Interface-protected Li Anode.

With theoretically endowing with high energy densities and environmentally friendly carbon neutralization ability, flexible fiber-shaped Li-CO2 battery emerges as a multipurpose platform for next-generation wearable electronics. Nevertheless, the ineluctable issues faced by cathode catalysts and Li anodes have brought enormous obstacles to the development of flexible fiber-shaped Li-CO2 batteries. Herein, a flexible fiber-shaped Li-CO2 battery based on Mo3 N2 cathode coating with atomic layer deposited TiN and Li3 N protected Li anode is constructed. Owing to the regulation surface electrons of Mo3 N2 by TiN, heterostructured cathode has more delocalized electrons which enable cathodes to stabilize 2-electron intermediate products Li2 C2 O4 by electron bridge bonds and avoid disproportionation into Li2 CO3 . Li3 N layers not only accelerate Li+ transportation but also avoid contact between Li and CO2 to form Li2 CO3 . Thus, the constructed Li-CO2 battery demonstrates a low charge potential of 3.22 V, low overpotential of 0.56 V, outstanding rate capabilities up to 1 A g-1 , and excellent long-term cycling (≈2000 h) with an energy efficiency of ≈80%. The fabricated flexible fiber-shaped Li-CO2 battery shows an ultrahigh energy density of 14 772.5 Wh kg-1 based on cathodes (340.8 Wh kg-1 based on device mass), and outstanding deformations adaptability, giving it great potential for wearable electronics.

Synthetic CRISPR/dCas9-KRAB system driven by specific PSA promoter suppresses malignant biological behavior of prostate cancer cells through negative feedback inhibition of PSA expression.

PSA is a type of proto-oncogene that is specifically and highly expressed in embryonic and prostate cancer cells, but not expressed in normal prostate tissue cells. The specific expression of prostate-specific antigen (PSA) is found to be related with the conditional transcriptional regulation of its promoter. Clustered regularly interspaced short palindromic repeats (CRISPR)-dCas9-KRAB is a newly developed transcriptional regulatory system that inhibits gene expression by interupting the DNA transcription process. Induction of CRISPR-dCas9-KRAB expression through the PSA promoter may help feedback inhibition of cellular PSA gene expression via single guide RNA (sgRNA), thereby monitoring and suppressing the malignant state of tumor cells. In this study, we examined the transcriptional activity of the PSA promoter in different prostate cancer cells and normal prostate epithelial cells and determined that it is indeed a prostate cancer cell-specific promoter.Then we constructed the CRISPR-dCas9-KRAB system driven by the PSA promoter, which can inhibit PSA gene expression in the prostate cancer cells at the transcriptional level, and therefore supress the malignant growth and migration of prostate cancer cells and promote their apoptosis in vitro. This study provides a potentially effective anti-cancer strategy for gene therapy of prostate cancer.

Unraveling Sequence Effect on Glass Transition Temperatures of Discrete Unconjugated Oligomers.

Sequence plays a critical role in enabling unique properties and functions of natural biomolecules, which has promoted the rapid advancement of synthetic sequence-defined polymers in recent decades. Particularly, investigation of short chain sequence-defined oligomers (also called discrete oligomers) on their properties has become a hot topic. However, most studies have focused on discrete oligomers with conjugated structures. In contrast, unconjugated oligomers remain relatively underexplored. In this study, three pairs of discrete oligomers with the same composition but different sequence for each pair are employed for investigating their glass transition temperatures (Tg s). The resultant Tg s of sequenced oligomers in each pair are found to be significantly different (up to 11.6 °C), attributable to variations in molecular packing as demonstrated by molecular dynamics and density function theory simulations. Intermolecular interaction is demonstrated to have less impact on Tg s than intramolecular interaction. The mechanistic investigation into two model dimers suggests that monomer sequence caused the difference in intramolecular rotational flexibility of the sequenced oligomers. In addition, despite having different monomer sequence and Tg s, the oligomers have very similar solubility parameters, which supports their potential use as effective oligomeric plasticizers to tune the Tg s of bulk polymer materials.

Unraveling Reaction Mechanisms of Mo2C as Cathode Catalyst in a Li-CO2 Battery.

First-principles density functional theory calculations are first used to study possible reaction mechanisms of molybdenum carbide (Mo2C) as cathode catalysts in Li-CO2 batteries. By systematically investigating the Gibbs free energy changes of different intermediates during lithium oxalate (Li2C2O4) and lithium carbonate (Li2CO3) nucleations, it is theoretically demonstrated that Li2C2O4 could be stabilized as the final discharge product, preventing the further formation of Li2CO3. The surface charge distributions of Li2C2O4 adsorbing onto catalytic surfaces are studied by using Bader charge analysis, given that electron transfers are found between Li2C2O4 and Mo2C surfaces. The catalytic activities of catalysts are intensively evaluated toward the discharge and charge processes by calculating the electrochemical free energy diagrams to identify the overpotentials. Our studies promote the understanding of electrochemical processes and shed more light on the design and optimization of cathode catalysts for Li-CO2 batteries.

Ultrafine nanosulfur particles sandwiched in little oxygen-functionalized graphene layers as cathodes for high rate and long-life lithium-sulfur batteries.

Although lithium-sulfur batteries are one of the promising candidates for next-generation energy storage systems, the practical applications are still hampered by the poor cycle life, which can be attributed to the insulating properties of sulfur and the shuttle effect of electrochemical intermediate polysulfides. To address these problems, we synthesize sandwich-like composites which consist of ultrafine nanosulfur particles enveloped by little oxygen-functionalized graphene layers (F-GS@S). In this structure, the little oxygen-functionalized graphene backbone can not only accelerate the redox kinetics of sulfur species, but also eliminate the shuttle effect of polysulfides by strong chemical interaction. Moreover, the sandwich confinement structures can further inhibit the dissolution of polysulfides by physical restraint and accommodate the volume contraction/expansion of sulfur during cycling. As a result, the F-GS@S composites used as cathodes for lithium-sulfur batteries display a superior rate capability with the high capacities of 1208 mAh g-1 at 0.1 C and 601.7 mAh g-1 at 2 C and high cycling stability with a capacity retention of 70.5% after 500 cycles at 2 C. In situ characterizations and real-time monitoring experiments during the charge-discharge process are carried out to elucidate the reaction mechanism of the F-GS@S composites as cathodes for high rate and long-life lithium-sulfur batteries.

[Medication versus health education for patients with type â ¢ prostatitis-like symptoms: A prospective randomized control study].

OBJECTIVE: To investigate the necessity of medication for patients with type Ⅲ prostatitis-like symptoms for less than 3 months. METHODS: We enrolled in this study 171 outpatients with type Ⅲ prostatitis-like symptoms for less than 3 months in our hospital from November 2016 to October 2017, and randomly divided them into groups A (n = 57), B (n = 57) and C (n = 57). The patients of group A received tamsulosin, levofloxacin and health education, those of group B tamsulosin and health education, and those of group C health education only. Three months later, we evaluated the therapeutic effects according to the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) scores of the patients, 4-point reduction in the total score indicating effectiveness. RESULTS: After 3 months of treatment, the total NIH-CPSI scores of the patients in groups A, B and C were decreased by (9.0 ± 2.9), (8.2 ± 3.4) and (8.6 ± 3.2) points respectively, all indicating effectiveness, the pain scores (4.2 ± 1.8), (4.0 ± 1.9) and (4.2 ± 1.6) points, the urinary symptom scores decreased by decreased by (2.4 ± 1.2), (2.4 ± 1.4) and (2.2 ± 1.2) points, and quality of life scores decreased by (2.4 ± 1.4), (1.9 ± 1.4) and (2.2 ± 1.3) points, none with statistically significant difference among the three groups (P > 0.05). CONCLUSIONS: Health education is proved to have a therapeutic effect on type Ⅲ prostatitis-like symptoms similar to that of alpha receptor blockers.

First-principles studies of polar perovskite KTaO3 surfaces: structural reconstruction, charge compensation, and stability diagram.

Polar perovskite oxides are of considerable interest for developing advanced functional materials with exceptional electronic properties for their unique polar characters. A cleavage of polar perovskite oxides along the charged layers leads to an electrostatic instability on the cleaved surfaces, and a charge compensation is required to stabilize these surfaces. In this work, we have systemically studied 25 types of surface models of polar KTaO3 perovskite oxide, including (001), (110), and (111) surfaces with various types of surface terminations, using first-principles electronic structure calculations. The surface structural reconstruction, electronic structures, and thermodynamic properties including cleavage energy and surface energy are investigated. The phase stability diagrams of the (001), (110), and (111) surfaces are constructed with respect to the chemical potentials of component elements. The KO(001), O(110), and KO2(111) terminations are more likely to be formed than other types of terminations in corresponding surfaces, consistent with experimental observations on KTaO3(001) surfaces. This work provides useful guidance for accurate control of surface morphology for tailing functional properties of polar KTaO3 perovskite oxide.

Graphene oxide hydrogel as a restricted-area nanoreactor for synthesis of 3D graphene-supported ultrafine TiO2 nanorod nanocomposites for high-rate lithium-ion battery anodes.

Three-dimensional graphene-supported TiO2 nanorod nanocomposites (3D GS-TNR) are prepared using graphene oxide hydrogel as a restricted-area nanoreactor in the hydrothermal process, in which well-distributed TiO2 nanorods with a width of approximately 5 nm and length of 30 nm are conformally embedded in the 3D interconnected graphene network. The 3D graphene oxide not only works as a restricted-area nanoreactor to constrain the size, distribution and morphology of the TiO2; it also work as a highly interconnected conducting network to facilitate electrochemical reactions and maintain good structural integration when the nanocomposites are used as anode materials in lithium-ion batteries. Benefiting from the nanostructure, the 3D GS-TNR nanocomposites show high capacity and excellent long-term cycling capability at high current rates. The 3D GS-TNR composites deliver a high initial charge capacity of 280 mAh g-1 at 0.2 C and maintain a reversible capacity of 115 mAh g-1, with a capacity retention of 83% at 20 C after 1000 cycles. Meanwhile, compared with that of previously reported TiO2-based materials, the 3D GS-TNR nanocomposites show much better performance, including higher capacity, better rate capability and long-term cycling stability.

Size effects and odd-even effects in MoS2 nanosheets: first-principles studies.

Molybdenum disulfide (MoS2) nanostructures have been widely used as catalysts in the petroleum refinery industry for the hydrodesulfurization process, in which sulfur vacancies play a critical role in determining the catalytic activity. Here we report size effects and odd-even effects on the formation of sulfur vacancies in the triangular MoS2 nanosheets using first-principles calculations. By modeling four types of edge structures of MoS2 nanosheets, S-terminated edges are found to be energetically more favorable than Mo-terminated edges, and are then selected for studying energetics of sulfur vacancies. Two types of sulfur dimer vacancies at the center (VS@Cen) and at the corner (VS@Cnr) of the edges of S-terminated MoS2 nanosheets are modeled, respectively. Our results reveal a strong odd-even effect on the formation of sulfur dimer vacancies, particularly for small MoS2 nanosheets, in terms of the size of nanosheets that is defined by the number of Mo atoms on the edge. The VS@Cen dimer vacancy has a low formation energy at an even-number but a high formation energy at an odd-number, while the VS@Cnr dimer vacancy exhibits a complete opposite trend. These results indicate that small MoS2 nanosheets can exhibit unique material properties for catalytic applications.

High-mobility two-dimensional electron gas in SrGeO3- and BaSnO3-based perovskite oxide heterostructures: an ab initio study.

We explored the possibility of producing a high-mobility two-dimensional electron gas (2DEG) in the LaAlO3/SrGeO3 and LaGaO3/BaSnO3 heterostructures using first-principles electronic structure calculations. Our results show that the 2DEG occurs at n-type LaAlO3/SrGeO3 and LaGaO3/BaSnO3 interfaces. Compared to the prototype LaAlO3/SrTiO3, LaAlO3/SrGeO3 and LaGaO3/BaSnO3 systems yield comparable total interfacial charge carrier density but much lower electron effective mass (nearly half the value of LaAlO3/SrTiO3), thus resulting in about twice larger electron mobility and enhanced interfacial conductivity. This work demonstrates that SrGeO3 and BaSnO3 can be potential substrate materials to achieve a high-mobility 2DEG in the perovskite-oxide heterostructures.

Nb and Ta layer doping effects on the interfacial energetics and electronic properties of LaAlO3/SrTiO3 heterostructure: first-principles analysis.

The two-dimensional electron gas (2DEG) formed at the n-type (LaO)(+1)/(TiO2)(0) interface in the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) has emerged as a prominent research area because of its great potential for nanoelectronic applications. Due to its practical implementation in devices, desired physical properties such as high charge carrier density and mobility are vital. In this respect, 4d and 5d transition metal doping near the interfacial region is expected to tailor electronic properties of the LAO/STO HS system effectively. Herein, we studied Nb and Ta-doping effects on the energetics, electronic structure, interfacial charge carrier density, magnetic moment, and the charge confinements of the 2DEG at the n-type (LaO)(+1)/(TiO2)(0) interface of LAO/STO HS using first-principles density functional theory calculations. We found that the substitutional doping of Nb(Ta) at Ti [Nb(Ta)@Ti] and Al [Nb(Ta)@Al] sites is energetically more favorable than that at La [Nb(Ta)@La] and Sr [Nb(Ta)@Sr] sites, and under appropriate thermodynamic conditions, the changes in the interfacial energy of HS systems upon Nb(Ta)@Ti and Nb(Ta)@Al doping are negative, implying that the formation of these structures is energetically favored. Our calculations also showed that Nb(Ta)@Ti and Nb(Ta)@Al doping significantly improve the interfacial charge carrier density with respect to that of the undoped system, which is because the Nb(Ta) dopant introduces excess free electrons into the system, and these free electrons reside mainly on the Nb(Ta) ions and interfacial Ti ions. Hence, along with the Ti 3d orbitals, the Nb 4d and Ta 5d orbitals also contribute to the interfacial metallic states; accordingly, the magnetic moments on the interfacial Ti ions increase significantly. As expected, the Nb@Al and Ta@Al doped LAO/STO HS systems show higher interfacial charge carrier density than the undoped and other doped systems. In contrast, Nb@Ti and Ta@Ti doped systems may show higher charge carrier mobility because of the lower electron effective mass.

Adhesion of nanoparticles to polymer brushes studied with the ghost tweezers method.

Mechanisms of interactions between nanoparticles (NPs) and polymer brushes (PBs) are explored using dissipative particle dynamics simulations and an original "ghost tweezers" method that emulates lab experiments performed with optical or magnetic tweezers. The ghost tweezers method is employed to calculate the free energy of adhesion. Ghost tweezers represents a virtual harmonic potential, which tethers NP with a spring to a given anchor point. The average spring force represents the effective force of NP-PB interaction as a function of the NP coordinate. The free energy landscape of NP-PB interactions is calculated as the mechanical work needed to transfer NP from the solvent bulk to a particular distance from the substrate surface. With this technique, we explore the adhesion of bare and ligand-functionalized spherical NPs to polyisoprene natural rubber brush in acetone-benzene binary solvent. We examine two basic mechanisms of NP-PB interactions, NP adhesion at PB exterior and NP immersion into PB, which are governed by interplay between entropic repulsive forces and enthalpic attractive forces caused by polymer adsorption at the NP surface and ligand adsorption at the substrate. The relative free energies of the equilibrium adhesion states and the potential barriers separating these states are calculated at varying grafting density, NP size, and solvent composition.

Morphological transformations in polymer brushes in binary mixtures: DPD study.

Morphological transformations in polymer brushes in a binary mixture of good and bad solvents are studied using dissipative particle dynamics simulations drawing on a characteristic example of polyisoprene natural rubber in an acetone-benzene mixture. A coarse-grained DPD model of this system is built based on the experimental data in the literature. We focus on the transformation of dense, collapsed brush in bad solvent (acetone) to expanded brush solvated in good solvent (benzene) as the concentration of benzene increases. Compared to a sharp globule-to-coil transition observed in individual tethered chains, the collapsed-to-expanded transformation in brushes is found to be gradual without a prominent transition point. The transformation becomes more leveled as the brush density increases. At low densities, the collapsed brush is highly inhomogeneous and patterned into bunches composed of neighboring chains due to favorable polymer-polymer interaction. At high densities, the brush is expanded even in bad solvent due to steric restrictions. In addition, we considered a model system similar to the PINR-acetone-benzene system, but with the interactions between the solvent components worsened to the limit of miscibility. Enhanced contrast between good and bad solvents facilitates absorption of the good solvent by the brush, shifting the collapsed-to-expanded transformation to lower concentrations of good solvent. This effect is especially pronounced for higher brush densities.

Oxygen Transport through Amorphous Cathode Coatings in Solid-State Batteries.

All solid-state batteries (SSBs) are considered the most promising path to enabling higher energy-density portable energy, while concurrently improving safety as compared to current liquid electrolyte solutions. However, the desire for high energy necessitates the choice of high-voltage cathodes, such as nickel-rich layered oxides, where degradation phenomena related to oxygen loss and structural densification at the cathode surface are known to significantly compromise the cycle and thermal stability. In this work, we show, for the first time, that even in an SSB, and when protected by an intact amorphous coating, the LiNi0.5Mn0.3Co0.2O2 (NMC532) surface transforms from a layered structure into a rocksalt-like structure after electrochemical cycling. The transformation of the surface structure of the Li3B11O18 (LBO)-coated NMC532 cathode in a thiophosphate-based solid-state cell is characterized by high-resolution complementary electron microscopy techniques and electron energy loss spectroscopy. Ab initio molecular dynamics corroborate facile transport of O2- in the LBO coating and in other typical coating materials. This work identifies that oxygen loss remains a formidable challenge and barrier to long-cycle life high-energy storage, even in SSBs with durable, amorphous cathode coatings, and directs attention to considering oxygen permeability as an important new design criteria for coating materials.

CNT@Fe3O4@C coaxial nanocables: one-pot, additive-free synthesis and remarkable lithium storage behavior.

By using carbon nanotubes (CNTs) as a shape template and glucose as a carbon precursor and structure-directing agent, CNT@Fe3O4@C porous core/sheath coaxial nanocables have been synthesized by a simple one-pot hydrothermal process. Neither a surfactant/ligand nor a CNT pretreatment is needed in the synthetic process. A possible growth mechanism governing the formation of this nanostructure is discussed. When used as an anode material of lithium-ion batteries, the CNT@Fe3O4@C nanocables show significantly enhanced cycling performance, high rate capability, and high Coulombic efficiency compared with pure Fe2O3 particles and Fe3O4/CNT composites. The CNT@Fe3O4@C nanocables deliver a reversible capacity of 1290 mA h g(-1) after 80 cycles at a current density of 200 mA g(-1), and maintain a reversible capacity of 690 mA h g(-1) after 200 cycles at a current density of 2000 mA g(-1). The improved lithium storage behavior can be attributed to the synergistic effect of the high electronic conductivity support and the inner CNT/outer carbon buffering matrix.

Ultrastretchable, Multihealable, and Highly Sensitive Strain Sensor Based on a Double Cross-Linked MXene Hydrogel.

The ability of a flexible strain sensor to directly adapt the complicated human biological motion or combined gestures and remotely control the artificial intelligence robotics could benefit the wearable electronics such as intelligent robotics and patient healthcare. However, it is a challenge for the flexible strain sensor to simultaneously achieve high sensing performances and stretchability and long sustainability under various deformation stress or damage. Herein, a dual-cross-linked poly(acrylic acid-stearyl methacrylate)/MXene [P(AA-SMA)M] hydrogel with enhanced mechanical stretchability and self-healability is fabricated by importing reversible coordination and hydrophobic interaction into polymer networks. As a result, the hydrogel film not only exhibits high tensile strength (525 kPa) and stretchability (∼2600%) but also achieves repetitive healable property with 843% elongation even after the 20th broken/self-healing cycle. More importantly, the resultant strain sensor delivers a low detection limit, wide sensing range, fast response time, and repeatability of 1000 cycles even after repeated self-healing. So, the sensor can monitor subtle human motions and recognize different handwriting and gestures, which reveals potential applications toward health-care devices, flexible electronics, and human-machine interfacing.

Strategies Toward Stretchable Aqueous Zn-based Batteries for Wearable Electronics from Components to Devices.

Recently, aqueous Zn-based batteries (AZBs) are receiving increased attention in wearable and implantable electronics due to the low cost, high safety, high eco-efficiency, and relatively high energy density. However, it is still a big challenge to develop stretchable AZBs (SAZBs) which can be conformally folded, crumpled, and stretched with human body motions. Although a lot of efforts have been dedicated to constructions of SAZBs, a comprehensive review which focuses on summarizing stretchable materials, device configurations and challenges of SAZBs is needed. Herein, this review attempts to critically review the latest developments and progress in stretchable electrodes, electrolytes, packaging materials and device configurations in detail. Furthermore, these challenges and potential future research directions in the field of SAZBs are also discussed.