RESUMEN
A B-site ordered double perovskite oxide Cd2CrSbO6 was synthesized under high-pressure and high-temperature conditions. The compound crystallizes to a monoclinic structure with a space group of P21/n. The charge configuration is confirmed to be that of Cd2+/Cr3+/Sb5+. The magnetic Cr3+ ions form a tetrahedral structural frustrated lattice, while a long-range ferromagnetic phase transition is found to occur at TC = 16.5 K arising from the superexchange interaction via the Cr-O-Cd-O-Cr pathway. Electrical transport measurements indicate that Cd2CrSbO6 is an insulator that can be described by the Mott 3D variable range hopping mechanism. First-principles calculations reproduce well the ferromagnetic and insulating ground state of Cd2CrSbO6 with an energy band gap of 1.55 eV. The intrinsic ferromagnetic insulating nature qualifies Cd2CrSbO6 as a promising candidate for possible spintronics applications.
RESUMEN
The ability to manipulate gene expression is valuable for elucidating gene function. In the fission yeast Schizosaccharomyces pombe, the most widely used regulatable expression system is the nmt1 promoter and its two attenuated variants. However, these promoters have limitations, including a long lag, incompatibility with rich media, and unsuitability for non-dividing cells. Here, we present a tetracycline-inducible system free of these shortcomings. Our system features the enotetS promoter, which achieves a similar induced level and a higher induction ratio compared to the nmt1 promoter, without exhibiting a lag. Additionally, our system includes four weakened enotetS variants, offering an expression range similar to the nmt1 series promoters but with more intermediate levels. To enhance usability, each promoter is combined with a Tet-repressor-expressing cassette in an integration plasmid. Importantly, our system can be used in non-dividing cells, enabling the development of a synchronous meiosis induction method with high spore viability. Moreover, our system allows for the shutdown of gene expression and the generation of conditional loss-of-function mutants. This system provides a versatile and powerful tool for manipulating gene expression in fission yeast.
RESUMEN
Acute-on-chronic liver failure (ACLF) and decompensated cirrhosis (DC) are life-threatening syndromes that can develop at the end-stage of chronic hepatitis B virus (HBV) infection. Both ACLF and DC are complicated by hepatic and extrahepatic pathogeneses. To better understand the compartment-specific metabolic modulations related to their pathogenesis, HBV-DC, HBV-ACLF patients, and controls (30 each) were analyzed by metabolomics using portal (Port), hepatic vein (Hep), and peripheral (Peri) serum. Compartment ratios of metabolites (RatioHep/Port, RatioPeri/Hep, and RatioPort/Peri) were calculated. The liver tissues (10 per group) were analyzed using transcriptomics and metabolomics. An additional 75 patients with ACLF, 20 with DC, and 20 with liver cirrhosis (LC) were used to confirm oxlipid dysregulation. Both multi-omics datasets suggest suppressed energy, amino acid, and pyrimidine metabolism in the ACLF/DC liver. The serum metabolomic variations were contributed primarily by disease rather than sampling compartments, as both HBV-ACLF and HBV-DC patients demonstrated abnormal profiles of amino acids and peptides, indoles, purines, steroids, and benzimidazoles. In ACLF/DC patients, impaired hepatic metabolism resulted in a highly correlated hepatic and portal vein serum metabolome and release of inflammatory lipids and heme metabolites from the liver. HBV-ACLF showed higher RatioPeri/Hep of extrahepatic inflammatory oxlipids, while HBV-DC patients showed higher RatioPort/Peri of gut microbial metabolites. An inflammatory oxlipid outburst was confirmed in the early stages of HBV-ACLF. The inflammatory effects of the selected oxlipids were confirmed in monocytes. These findings support a synergy between liver-specific mechanisms and systemic inflammation in ACLF/DC development, and that pro-inflammatory oxlipids are metabolic signatures of early HBV-ACLF.
Asunto(s)
Insuficiencia Hepática Crónica Agudizada , Virus de la Hepatitis B , Hepatitis B Crónica , Cirrosis Hepática , Hígado , Metabolómica , Humanos , Insuficiencia Hepática Crónica Agudizada/virología , Cirrosis Hepática/virología , Cirrosis Hepática/metabolismo , Masculino , Femenino , Hígado/metabolismo , Hígado/virología , Persona de Mediana Edad , Adulto , Hepatitis B Crónica/complicaciones , Hepatitis B Crónica/virología , Virus de la Hepatitis B/genética , MetabolomaRESUMEN
The rare physical property of negative thermal expansion (NTE) is intriguing because materials with a large NTE over a wide temperature range can serve as high-performance thermal expansion compensators. However, the applications of NTE are hindered by the fact that most of the available NTE materials show small magnitudes of NTE, and/or NTE occurs only in a narrow temperature range. Herein, for the first time, we investigated the effect of anion substitution instead of general Pb/Ti-site substitutions on the thermal expansion properties of a typical ferroelectric NTE material, PbTiO3. Intriguingly, the substitution of S for O in PbTiO3 further increases the tetragonality of PbTiO3. Consequently, an unusually enhanced NTE with an average volumetric coefficient of thermal expansion of îV = -2.50 × 10-5 K-1 was achieved over a wide temperature range (300-790 K), which is in contrast to that of pristine PbTiO3 (îV = -1.99 × 10-5 K-1, RT-763 K). The intensified NTE is attributed to the enhanced hybridization between Pb/Ti and O/S atoms by the substitution of S, as evidenced by our theoretical investigations. We therefore demonstrate a new technique for introducing mixed anions to achieve a large NTE over a wide temperature range in PbTiO3-based ferroelectrics.
RESUMEN
Objective: To systematically evaluate the efficacy of hyperbaric oxygen therapy (HBOT) as an adjunct therapy for treating sleep disorders in patients with Parkinson's disease (PD). Methods: We conducted comprehensive searches in eight databases from inception through September 2023, including PubMed, Cochrane Library, Embase, Web of Science, SinoMed, China National Knowledge Infrastructure (CNKI), China Science and Technology Periodical Database (VIP), and Wanfang Database. The objective was to identify randomized controlled trials (RCTs) evaluating HBOT's effectiveness in alleviating sleep disorder symptoms in PD patients as an adjunct therapy. Literature screening and data extraction were independently executed by the authors. Meta-analyses were performed using Review Manager 5.3 software, and publication bias and sensitivity analyses were assessed using Stata 17.0 software. Results: Seven RCTs involving 461 participants were included. The findings revealed that the addition of HBOT significantly enhanced sleep efficiency (MD = 15.26, 95% CI [10.89, 19.63], p < 0.00001), increased time in bed (MD = 69.65, 95% CI [43.01, 96.30], p < 0.00001), total sleep time (MD = 75.87, 95% CI [25.42, 126.31], p = 0.003), slow-wave sleep (SWS) time (MD = 6.14, 95% CI [3.95, 8.34], p < 0.00001), and rapid eye movement sleep (REM) time (MD = 4.07, 95% CI [2.05, 6.08], p < 0.0001), and reduced awakening frequency (MD = -11.55, 95% CI [-15.42, -7.68], p < 0.00001) and sleep latency (MD = -6.60, 95% CI [-9.43, -3.89], p < 0.00001). Additionally, significant improvements were observed in the Pittsburgh Sleep Quality Index (PSQI) (MD = -2.52, 95% CI [-2.85, -2.18], p < 0.00001), Epworth Sleepiness Scale (ESS) (MD = -2.90, 95% CI [-3.34, -2.47], p < 0.00001), Unified Parkinson's Disease Rating Scale Part III (UPDRS III) (MD = -1.32, 95% CI [-2.16, -0.47], p = 0.002), and Hoehn and Yahr grading (H-Y grading) (MD = -0.15, 95% CI [-0.28, -0.01], p = 0.03). Conclusion: The current meta-analysis supports the efficacy of HBOT as an adjunct therapy in managing sleep disorders in PD patients. It is recommended for PD patients experiencing sleep disturbances.Systematic review registration:https://www.crd.york.ac.uk/, identifier: CRD42023462201.
RESUMEN
As a model plant for bryophytes, Marchantia polymorpha offers insights into the role of RNA silencing in aiding early land plants navigate the challenges posed by high-temperature environments. Genomic analysis revealed unique ARGONAUTE1 ortholog gene (MpAGO1) in M. polymorpha, which is regulated by two species-specific microRNAs (miRNAs), miR11707.1 and miR11707.2. Comparative studies of small RNA profiles from M. polymorpha cellular and MpAGO1 immunoprecipitation (MpAGO1-IP) profiles at various temperatures, along with analyses of Arabidopsis AGO1 (AtAGO1), revealed that MpAGO1 has a low selectivity for a diverse range of small RNA species than AtAGO1. Protein structural comparisons revealed no discernible differences in the guide strand small RNA recognition middle domain, MID domain, of MpAGO1 and AtAGO1, suggesting the complexity of miRNA species specificity and necessitating further exploration. Small RNA profiling and size exclusion chromatography have pinpointed a subset of M. polymorpha miRNAs, notably miR11707, that remain in free form within the cell at 22°C but are loaded into MpAGO1 at 28°C to engage in RNA silencing. Investigations into the mir11707 gene editing (mir11707ge) mutants provided evidence of the regulation of miR11707 in MpAGO1. Notably, while MpAGO1 mRNA expression decreases at 28°C, the stability of the MpAGO1 protein and its associated miRNAs is essential for enhancing the RNA-inducing silencing complex (RISC) activity, revealing the importance of RNA silencing in enabling M. polymorpha to survive thermal stress. This study advances our understanding of RNA silencing in bryophytes and provides groundbreaking insights into the evolutionary resilience of land plants to climatic adversities.
Asunto(s)
Proteínas Argonautas , Regulación de la Expresión Génica de las Plantas , Marchantia , MicroARNs , Proteínas de Plantas , Marchantia/genética , Marchantia/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Aclimatación/genética , Calor , ARN de Planta/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Edición Génica , Arabidopsis/genética , Arabidopsis/metabolismoRESUMEN
Background: Synchroamedogensis, a new species of Synchroidae Lacordaire, 1859, is described and illustrated, based on a single male collected from Mêdog, Xizang, China. This new species is close to S.elongatula Nikitsky, 1999 and S.melanotoides Lewis, 1895, but could be distinguished by the elongated antennae and elytra, the apically narrowed prosternal process and the stout parameres. New information: The new information of this new species provided in this paper include: description, type information, distribution and comparison amongst S.medogensis sp. nov., S.elongatula and S.melanotoides.
RESUMEN
Platelet-rich plasma (PRP) holds promise as a therapeutic modality for wound healing; however, immediate utilization encounters challenges related to volume, concentration, and consistency. Cryopreservation emerges as a viable solution, preserving PRP's bioactive components and extending its shelf life. This study explores the practicality and efficacy of cryopreserved platelet-rich plasma (cPRP) in wound healing, scrutinizing both cellular mechanisms and clinical implications. Fresh PRP and cPRP post freeze-thaw underwent assessment in macrophage, fibroblast, and endothelial cell cultures. The impact of cPRP on active component release and cell behavior pertinent to wound healing was evaluated. Varied concentrations of cPRP (1%, 5%, 10%) were examined for their influence on cell polarization, migration, and proliferation. The results showed minimal changes in cPRP's IL-1ß levels, a slight decrease in PDGF-BB, and superior effects on macrophage M2 polarization and fibroblast migration, while no statistical significance was observed in endothelial cell angiogenesis and proliferation. Remarkably, 5% PRP exhibited the most significant stimulation among all cPRP concentrations, notably impacting cell proliferation, angiogenesis, and migration. The discussion underscores that cPRP maintains platelet phenotype and function over extended periods, with 5% cPRP offering the most favorable outcomes, providing a pragmatic approach for cold storage to extend post-thaw viability and amplify therapeutic effects.
What is the context? Platelet-rich plasma (PRP) is a potential bioactive material for wound healing, but using it immediately faces issues like volume, concentration, and consistency.Low-temperature freezing is a method employed to preserve PRP. However, the current understanding of the effects of the freezing-thawing process on the components of PRP and its impact on cells relevant to wound healing remains unclear.What is new? This study explores the feasibility and effectiveness of using cryopreserved PRP at −80°C for promoting wound healing. This research stands out for its focus on cellular responses and practical implications in therapeutic contexts.To understand their distinct impact on different cell types relevant to wound healing, the study meticulously examined various final concentrations of cPRP (1%, 5%, 10%).The study identified the superior effects of 5% cPRP on crucial cellular activities, notably in cell polarization, proliferation, angiogenesis, and migration.What is the impact? Low-temperature freezing can be considered an effective method for PRP preservation.Some bioactive components in cPRP exhibit subtle changes; however, these changes result in better effects on certain cell types related to healing.The study illustrates that all concentrations of cPRP effectively enhance cell proliferation, migration, and differentiation, emphasizing the comparable efficacy of cryopreserved PRP to non-cryopreserved PRP.
Asunto(s)
Criopreservación , Plasma Rico en Plaquetas , Cicatrización de Heridas , Plasma Rico en Plaquetas/metabolismo , Humanos , Criopreservación/métodos , Proliferación Celular , Movimiento Celular , Fibroblastos/metabolismoRESUMEN
Despite being the most widespread blister beetle subfamily, Nemognathinae is unfairly understudied in China. In this study, a new genus and species, Sinostenoria yangi Pan, from northern China is described and illustrated. The antennae, elytra, hind wings, and claws of the new genus form a truly unique set of characteristics never observed in other genera of Nemognathini Laporte de Castelnau, 1840. Three species from China are newly recorded and illustrated: Megatrachelus sibiricus (Tauscher, 1812), Zonitomorpha dollei (Fairmaire 1889), and Stenodera djakonovi Aksentjev, 1978. The genus Oreomeloe Tan, 1981, is transferred from the tribe Meloini Gyllenhal, 1910, to Nemognathini based on an examination of the types. Aiming to test the morphology-based placement of the new genus, we conducted molecular phylogenetic analyses using two mitochondrial (COI, 16S) and three nuclear markers (28S, CAD, ITS2). The results confirm our tribal assignment of the new genus and support a clade that consists of Sinostenoriagen. n., Longizonitis Pan and Bologna, 2018, Stenoria cf. grandiceps, and Ctenopus cf. persicus.
RESUMEN
INTRODUCTION: Neonatal respiratory failure (NRF) is a serious condition that often has high mortality and morbidity, effective interventions can be delivered in the future by identifying the risk factors associated with morbidity and mortality. However, recent advances in respiratory support have improved neonatal intensive care units (NICUs) care in China. We aimed to provide an updated review of the clinical profile and outcomes of NRF in the Jiangsu province. METHODS: Infants treated for NRF in the NICUs of 28 hospitals between March 2019 and March 2022 were retrospectively reviewed. Data collected included baseline perinatal and neonatal parameters, NICU admission- and treatment-related data, and patient outcomes in terms of mortality, major morbidity, and survival without major morbidities. RESULTS: A total of 5548 infants with NRF were included in the study. The most common primary respiratory disorder was respiratory distress syndrome (78.5%). NRF was managed with non-invasive and invasive respiratory support in 59.8% and 14.5% of patients, respectively. The application rate of surfactant therapy was 38.5%, while that of neonatal extracorporeal membrane oxygenation therapy was 0.2%. Mortality and major morbidity rates of 8.5% and 23.2% were observed, respectively. Congenital anomalies, hypoxic-ischemic encephalopathy, invasive respiratory support only and inhaled nitric oxide therapy were found to be significantly associated with the risk of death. Among surviving infants born at < 32 weeks of gestation or with a birth weight < 1500 g, caffeine therapy and repeat mechanical ventilation were demonstrated to significantly associate with increased major morbidity risk. CONCLUSION: Our study demonstrates the current clinical landscape of infants with NRF treated in the NICU, and, by proxy, highlights the ongoing advancements in the field of perinatal and neonatal intensive care in China.
Asunto(s)
Unidades de Cuidado Intensivo Neonatal , Síndrome de Dificultad Respiratoria del Recién Nacido , Humanos , Recién Nacido , China/epidemiología , Estudios Retrospectivos , Femenino , Masculino , Síndrome de Dificultad Respiratoria del Recién Nacido/terapia , Insuficiencia Respiratoria/terapia , Surfactantes Pulmonares/uso terapéutico , Surfactantes Pulmonares/administración & dosificación , Oxigenación por Membrana Extracorpórea , Respiración Artificial/estadística & datos numéricos , Resultado del TratamientoRESUMEN
The miR390-derived TAS3 trans-acting short-interfering RNAs (tasiRNAs) module represents a conserved RNA silencing pathway in the plant kingdom; however, its characterization in the bryophyte Marchantia polymorpha is limited. This study elucidated that MpDCL4 processes MpTAS3 double-stranded RNA (dsRNA) to generate tasiRNAs, primarily from the 5'- and 3'-ends of dsRNA. Notably, we discovered a novel tasiRNA, tasi78A, which can negatively regulate a cytochrome P450 gene, MpCYP78A101. Additionally, tasi78A was abundant in MpAGO1, and transient expression assays underscored the role of tasi78A in repressing MpCYP78A101. A microRNA, miR11700, also regulates MpCYP78A101 expression. This coordinate regulation suggests a role in modulating auxin signaling at apical notches of gemma, influencing the growth and sexual organ development of M. polymorpha and emphasizing the significance of RNA silencing in MpCYP78A101 regulation. However, phylogenetic analysis identified another paralog of the CYP78 family, Mp1g14150, which may have a redundant role with MpCYP78A101, explaining the absence of noticeable morphological changes in loss-of-function plants. Taken together, our findings provide new insights into the combined regulatory roles of miR390/MpTAS3/miR11700 in controlling MpCYP78A101 and expand our knowledge about the biogenesis and regulation of tasiRNAs in M. polymorpha.
Asunto(s)
Sistema Enzimático del Citocromo P-450 , Regulación de la Expresión Génica de las Plantas , Marchantia , MicroARNs , ARN Interferente Pequeño , Marchantia/genética , MicroARNs/genética , MicroARNs/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Filogenia , ARN de Planta/genética , ARN de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
A transition-metal oxide of PbCu3Mn4O12 was prepared at 1523 K and 10 GPa. An A-site-ordered quadruple perovskite structure with the space group Im3Ì is assigned for this compound. Based on bond-valence-sum calculations and X-ray absorption spectroscopy, the charge combination is determined to be PbCu32+Mn44+O12. Due to Cu2+(↑)-Mn4+(↓) antiferromagnetic coupling, a near-room-temperature ferrimagnetic phase transition is observed at approximately 287 K. PbCu3Mn4O12 exhibits a semiconducting electric transport property with the energy band gap Eg ≈ 0.2 eV. In addition, considerable low-field magnetoresistance effects are observed at lower temperatures. This study provides an intrinsic near-room-temperature ferrimagnetic semiconductor that exhibits potential applications in next-generation spintronic devices.
RESUMEN
Eupyrochroa Blair, 1914 is a small genus of fire-colored beetles (Coleoptera: Pyrochroidae) with two putative species recorded from limited historical distributions in China. The two species, E. insignita (Fairmaire, 1894) and E. limbaticollis (Pic, 1909), have been distinguished on the basis of color differences in the pronotum and scutellum, characters now known to exhibit significant variability. In the present study, adult morphology of the two species was compared, and partial fragments of cytochrome c oxidase subunit I (COI) from 36 samples representing 14 pyrochroid species were obtained by extraction and a GenBank search. Nucleotide composition, genetic distance, and phylogeny were analyzed. The results of morphological and molecular analyses indicate consistency, suggesting that the two species are indistinguishable by any significant measure. Therefore, Eupyrochroa limbaticollis (Pic, 1909) is proposed as a junior synonym of E. insignita (Fairmaire, 1894). The species is also redescribed and illustrated, including both adults and larvae.
Asunto(s)
Escarabajos , Animales , Filogenia , Larva , Bases de Datos de Ácidos NucleicosRESUMEN
Oblatopyrochroabellula, a new genus and species of Pyrochroinae Latreille, 1807 from Xizang, China, is described and illustrated. The antennae, cranial apparatus, and genitalia of the new genus form a truly unique set of characters not observed in any other pyrochroid genus. The taxonomic position and phylogenetic relationships of Oblatopyrochroagen. nov. are also discussed but appear difficult to resolve.
RESUMEN
The adult, pupa and larva of a new species, Gnaptorina (Gnaptorina) lhorongica Li, sp. nov., from northeastern Xizang, China are described and illustrated. The species was identified using molecular phylogenetic analyses based on three mitochondrial fragments and one nuclear gene fragment (COI, Cytb, 16S, and 28S-D2). The taxonomic status of the new species is confirmed using a combination of molecular and morphological datasets. This study provides valuable molecular and morphological data for phylogenetic studies of the tribe Blaptini.
RESUMEN
BACKGROUND: Microglia-mediated neuroinflammation is a hallmark of neurodegeneration. Metabotropic glutamate receptor 8 (GRM8) has been reported to promote neuronal survival in neurodegenerative diseases, yet the effect of GRM8 on neuroinflammation is still unclear. Calcium overload-induced endoplasmic reticulum (ER)-mitochondrial miscommunication has been reported to trigger neuroinflammation in the brain. The aim of this study was to investigate putative anti-inflammatory effects of GRM8 in microglia, specifically focusing on its role in calcium overload-induced ER stress and mitochondrial dysfunction. METHODS: BV2 microglial cells were pretreated with GRM8 agonist prior to lipopolysaccharide administration. Pro-inflammatory cytokine levels and the microglial polarization state in BV2 cells were then quantified. Cellular apoptosis and the viability of neuron-like PC12 cells co-cultured with BV2 cells were examined using flow cytometry and a Cell Counting Kit-8, respectively. The concentration of cAMP, inositol-1,4,5-triphosphate receptor (IP3R)-dependent calcium release, ER Ca2+ concentration, mitochondrial function as reflected by reactive oxygen species levels, ATP production, mitochondrial membrane potential, expression of ER stress-sensing protein, and phosphorylation of the nuclear factor kappa B (NF-κB) p65 subunit were also quantified in BV2 cells. RESULTS: GRM8 activation inhibited pro-inflammatory cytokine release and shifted microglia polarization towards an anti-inflammatory-like phenotype in BV2 cells, as well as promoting neuron-like PC12 cell survival when co-cultured with BV2 cells. Mechanistically, microglial GRM8 activation significantly inhibited cAMP production, thereby desensitizing the IP3R located within the ER. This process markedly limited IP3R-dependent calcium release, thus restoring mitochondrial function while inhibiting ER stress and subsequently deactivating NF-κB signaling. CONCLUSIONS: Our results indicate that GRM8 activation can protect against microglia-mediated neuroinflammation by attenuating ER stress and mitochondrial dysfunction, and that IP3R-mediated calcium signaling may play a vital role in this process. GRM8 may thus be a potential target for limiting neuroinflammation.
Asunto(s)
Microglía , Enfermedades Mitocondriales , Receptores de Glutamato Metabotrópico , Ratas , Animales , FN-kappa B/metabolismo , Enfermedades Neuroinflamatorias , Calcio/metabolismo , Citocinas/metabolismo , Antiinflamatorios/metabolismo , Antiinflamatorios/farmacología , Estrés del Retículo Endoplásmico , Enfermedades Mitocondriales/metabolismoRESUMEN
An AA'3B2B'2O12-type quadruple perovskite oxide of CaCu3Cr2Re2O12 was synthesized at 18 GPa and 1373 K. Both an A- and B-site ordered quadruple perovskite crystal structure was observed, with the space group Pn-3. The valence states are verified to be CaCu32+Cr23+Re25+O12 by bond valence sum calculations and synchrotron X-ray absorption spectroscopy. The spin interaction among Cu2+, Cr3+, and Re5+ generates a ferrimagnetic transition with the Curie temperature (TC) at about 360 K. Moreover, electric transport properties and specific heat data suggest the presence of a half-metallic feature for this compound. The present study provides a promising quadruple perovskite oxide with above-room-temperature ferrimagnetism and possible half-metallic properties, which shows potential in the usage of spintronic devices.
RESUMEN
On-chip micro-ring resonators (MRRs) with low loss and large free spectral ranges (FSRs) are important for photonic devices. So far, ultra-low-loss silicon-nitride (Si3N4) waveguides are primarily fabricated in laboratories, as they often demand special processes to reduce transmission losses. While, Si3N4 waveguides fabricated by the standard multi-project wafer (MPW)-based processes often suffer from significant sidewall scattering, resulting in high scattering losses. Here, we present an innovative approach to photonics by introducing a compact and multi-mode structure. This approach significantly reduces the contact between the optical field and the rough sidewalls in the high-confinement Si3N4 waveguide. By incorporating modified Euler bends, and a weakly tapered gap directional coupler, adiabatic transmission with simultaneous ultra-low loss and compact size is achieved even in 7-µm wide waveguide. Results show that the intrinsic quality factor Qi of MRR is (6.8 ± 0.4) × 106 at the wavelength of 1550â nm, which is approximately four times higher than the previously reported by the same fabrication process. An ultra-low loss of 0.051 ± 0.003â dB/cm is achieved based on the standard LIGENTEC-AN800 technology. This accomplishment addresses a critical challenge in high-confinement waveguides. Our work provides new insights into the low propagation loss in Si3N4 waveguides and provides a broader prospect for integrated photonics in the ultra-high-Q regime.
RESUMEN
The development of magnetocaloric materials with a significantly enhanced volumetric cooling capability is highly desirable for the application of adiabatic demagnetization refrigerators in confined spatial environments. Here, the thermodynamic characteristics of a magnetically frustrated spin-7/2 Gd9.33[SiO4]6O2 is presented, which exhibits strongly correlated spin disorder below ≈1.5 K. A quantitative model is proposed to describe the magnetization results by incorporating nearest-neighbor Heisenberg antiferromagnetic and dipolar interactions. Remarkably, the recorded magnetocaloric responses are unprecedentedly large and applicable below 1.0 K. It is proposed that the S = 7/2 spin liquids serve as versatile platforms for investigating high-performance magnetocaloric materials in the sub-kelvin regime, particularly those exhibiting a superior cooling power per unit volume.
RESUMEN
Designing a multifunctional electrocatalyst to produce H2 from water, urea, urine, and wastewater, is highly desirable yet challenging because it demands precise Fermi-engineering to realize stronger π-donation from O 2p to electron(e-)-deficient metal (t2g) d-orbitals. Here a Sr-induced phase transformed ß-FeOOH/α-Ni(OH)2 catalyst anchored on Ni-foam (designated as pt-NFS) is introduced, where Sr produces plenteous Fe4+ (Fe3+ â Fe4+) to modulate Fermi level and e--transfer from e--rich Ni3+(t2g)-orbitals to e--deficient Fe4+(t2g)-orbitals, via strong π-donation from the π-symmetry lone-pair of O bridge. pt-NFS utilizes Fe-sites near the Sr-atom to break the HâOâH bonds and weakens the adsorption of *O while strengthening that of *OOH, toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Invaluably, Fe-sites of pt-NFS activate H2-production from urea oxidation reaction (UOR) through a one-stage pathway which, unlike conventional two-stage pathways with two NH3-molecules, involves only one NH3-molecule. Owing to more suitable kinetic energetics, pt-NFS requires 133 mV (negative potential shift), 193 mV, ≈1.352 V, and ≈1.375 V versus RHE for HER, OER, UOR, and human urine oxidation, respectively, to reach the benchmark 10 mA cm-2 and also demonstrates remarkable durability of over 25 h. This work opens a new corridor to design multifunctional electrocatalysts with precise Fermi engineering through d-band modulation.