Anisotropic Electron-Phonon Interactions in 2D Lead-Halide Perovskites.

Two-dimensional (2D) hybrid organic-inorganic metal halide perovskites offer enhanced stability for perovskite-based applications. Their crystal structure's soft and ionic nature gives rise to strong interaction between charge carriers and ionic rearrangements. Here, we investigate the interaction of photogenerated electrons and ionic polarizations in single-crystal 2D perovskite butylammonium lead iodide (BAPI), varying the inorganic lamellae thickness in the 2D single crystals. We determine the directionality of the transition dipole moments (TDMs) of the relevant phonon modes (in the 0.3-3 THz range) by the angle- and polarization-dependent THz transmission measurements. We find a clear anisotropy of the in-plane photoconductivity, with a ∼10% reduction along the axis parallel with the transition dipole moment of the most strongly coupled phonon. Detailed calculations, based on Feynman polaron theory, indicate that the anisotropy originates from directional electron-phonon interactions.

Effect of External Electric Field on Nitrogen Activation on a Trimetal Cluster.

Efficient nitrogen (N2) fixation and activation under mild conditions are crucial for modern society. External electric fields (Felectric) can significantly affect N2 activation. In this work, the effect of Felectric on N2 activation by Nb3 clusters supported in a sumanene bowl was studied by density functional theory calculations. Four typical systems at different stages of N-N activation were studied, including two intermediates and two transition states. The impact of Felectric on various properties related to N2 activation was investigated, including the N-N bond length, overlap population density of states (OPDOS), total energy of the system, adsorption energy of N2, decomposition of energy changes, and electron transfer. The sumanene not only functions as a support and protective substrate, but also serves as a donor or acceptor under different Felectric conditions. Negative Felectric is beneficial to N-N bond activation because it promotes electron transfer to the N-N region and improves the d-π* orbital hybridization between metals and N2 in the activation process. Positive Felectric improves d-π* orbital hybridization only when the N-N is nearly dissociated. The microscopic mechanism of Felectric's effects provides insight into N2 activation and theoretical guidance for the design of catalytic reaction conditions for nitrogen reduction reactions (NRR).

Plant growth promoting rhizobacteria induced metal and salt stress tolerance in Brassica juncea through ion homeostasis.

Soil heavy metal contamination and salinity constitute a major environmental problem worldwide. The affected area and impact of these problems are increasing day by day; therefore, it is imperative to restore their potential using environmentally friendly technology. Plant growth-promoting rhizobacteria (PGPR) provides a better option in this context. Thirty-seven bacteria were isolated from the rhizosphere of maize cultivated in metal- and salt-affected soils. Some selected bacterial strains grew well under a wide range of pH (4-10), salt (5-50 g/L), and Cd (50-1000 mg/L) stress. Three bacterial strains, Exiguobacterium aestuarii (UM1), Bacillus cereus (UM8), and Bacillus megaterium (UM35), were selected because of their robust growth and high tolerance to both stress conditions. The bacterial strains UM1, UM8, and UM35 showed P-solubilization, whereas UM8 and UM35 exhibited 1-aminocyclopropane-1-carboxylate deaminase activity and indole acetic acid (IAA) production, respectively. The bacterial strains were inoculated on Brassica juncea plants cultivated in Cd and salt-affected soils due to the above PGP activities and stress tolerance. Plants inoculated with the bacterial strains B. cereus and B. megaterium significantly (p < 0.05) increased shoot fresh weight (17 ± 1.17-29 ± 0.88 g/plant), shoot dry weight (2.50 ± 0.03-4.40 ± 0.32 g/plant), root fresh weight (7.30 ± 0.58-13.30 ± 0.58 g/plant), root dry weight (0.80 ± 0.04-2.00 ± 0.01 g/plant), and shoot K contents (62.76 ± 1.80-105.40 ± 1.15 mg/kg dwt) in normal and stressful conditions. The bacterial strain B. megaterium significantly (p < 0.05) decreased shoot Na+ and Cd++ uptake in single and dual stress conditions. Both bacterial strains, E. aestuarii and B. cereus, efficiently reduced Cd++ translocation and bioaccumulation in the shoot. Bacterial inoculation improved the uptake of K+ and Ca++, while restricted Na+ and Cd++ in B. juncea shoots indicated their potential to mitigate the dual stresses of salt and Cd in B. juncea through ion homeostasis.

Reliability of Longshi scale with remote assessment of smartphone video calls for stroke patients' activities of daily living.

OBJECTIVES: The impairment of activities of daily living (ADL) has brought a heavy burden to the life of patients after stroke. Timely and accurate assessment of patients' activities of daily living is very necessary, which determines the whole process of diagnosis, rehabilitation and prognosis of patients. However, the patients with limited mobility or transportation are difficulted to gain high quality assessment services. This study aimed to explore the reliability of remote Longshi Assessment Scale of Activities of Daily Life (Longshi Scale) with smartphone video calls by comparing the consistency of remote assessment and bedside assessment, as well as the test-retest reliability of the remote assessment. The evaluation duration of these two methods was recorded and the level of satisfaction of patients was investigated. METHODS: In this prospective study, a total of 129 stroke survivors were recruited and accepted a bedside face-to-face assessment and a remote assessment by video calls. The Longshi Scale was used for both bedside and remote assessment and conducted with the inquiry between patients and evaluators. A satisfaction questionnaire was also launched. RESULTS: The result of disability level evaluated from the bedside and remote assessments was highly consistent. The intraclass correlation coefficient with weighted kappa (wK) value was 0.86 (95% confidence interval, 0.80∼0.92). And test-retest of the remote assessment indicated an excellent agreement beyond chance, and its correlation coefficient with wK value was 0.96 (95% confidence interval, 0.92∼1.00). It took 74.44±55.3 s to complete the bedside assessment and 90.86±63.30 s to complete the remote assessment of Longshi Scale. There was no statistical significance in the assessment duration between these two methods (P = 0.056). Satisfaction surveys showed more than 85% of participants were satisfied or very satisfied with remote Longshi scale assessment. CONCLUSIONS: The remote assessment of Longshi Scale with smartphone video calls is reliable and has high acceptance. This method can be readily implemented to evaluate the ADL of stroke patients to improve the capacity of rehabilitation and health services in remote areas.

Modeling Methods and Influencing Factors for Age Estimation Based on DNA Methylation.

Age estimation based on tissues or body fluids is an important task in forensic science. The changes of DNA methylation status with age have certain rules, which can be used to estimate the age of the individuals. Therefore, it is of great significance to discover specific DNA methylation sites and develop new age estimation models. At present, statistical models for age estimation have been developed based on the rule that DNA methylation status changes with age. The commonly used models include multiple linear regression model, multiple quantile regression model, support vector machine model, artificial neural network model, random forest model, etc. In addition, there are many factors that affect the level of DNA methylation, such as the tissue specificity of methylation. This paper reviews these modeling methods and influencing factors for age estimation based on DNA methylation, with a view to provide reference for the establishment of age estimation models.

Investigation on forced vibration characteristics of Nitinol tracheal stent.

BACKGROUND: Tracheal stents can be placed in a narrow position in the human trachea to ensure smooth breathing. And the stent will deform during service by the influence of the physiological environment or random excitations, such as coughing. METHODS: This paper divides the vibration into periodic and random vibrations according to the different pressures. And a coupling vibration model was established by analyzing the contact relationship between the stent and the trachea tissue. And this study discusses the influence of tracheal diameter, respiratory pressure, and frequency on the stent vibration characteristics through Ansys simulation. In addition, the nonlinear equations were solved by the Matlab numerical analysis method, which could help analyze the influence of cough intensity on the stability of the tracheal stent system. RESULTS: The results showed that when tracheal stenosis occurred in the trachea's more significant grade, the trachea stent was more likely to fall off when treated with a tracheal stent. With the increase in respiratory frequency and pressure, the deformation of the tracheal stent is more considerable. Moreover, the frequency of normal cough hardly affects the stability of the stent system, while the excitation force and damping coefficient value greatly influence the system. When the excitation force of the cough exceeds the critical importance of 20 N, the tracheal stent is prone to fall off. This study comprehensively obtained the forced vibration characteristics of the stent under service conditions, which could make up for the shortage of the vibration theory of the stent. CONCLUSION: The results can provide a theoretical basis for predicting the possibility of stent loss in clinical treatment.

Interactive effects of aquatic nitrogen and plant biomass on nitrous oxide emission from constructed wetlands.

Understanding of mechanisms in nitrous oxide (N2O) emission from constructed wetland (CW) is particularly important for the establishment of related strategies to reduce greenhouse gas (GHG) production during its wastewater treatment. However, plant biomass accumulation, microbial communities and nitrogen transformation genes distribution and their effects on N2O emission from CW as affected by different nitrogen forms in aquatic environment have not been reported. This study investigated the interactive effects of aquatic nitrogen and plant biomass on N2O emission from subsurface CW with NH4+-N (CW-A) or NO3--N (CW-B) wastewater. The experimental results show that NH4+-N and NO3--N removal efficiencies from CW mesocosms were 49.4% and 87.6%, which indirectly lead to N2O emission fluxes of CW-A and CW-B maintained at 213 ± 67 and 462 ± 71 µg-N/(m2·h), respectively. Correlation analysis of nitrogen conversion dynamic indicated that NO2--N accumulation closely related to N2O emission from CW. Aquatic NH4+-N could up-regulate plant biomass accumulation by intensifying citric acid cycle, glycine-serine-threonine metabolism etc., resulting in more nitrogen uptake and lower N2O emission/total nitrogen (TN) removal ratio of CW-A compared to CW-B. Although the abundance of denitrifying bacteria and N2O reductase nosZ in CW-B were significantly higher than that of CW-A, after fed with mixed NH4+-N and NO3--N influent, N2O fluxes and N2O emission/TN removal ratio in CW-A were extremely close to that of CW-B, suggesting that nitrogen form rather than nitrogen transformation microbial communities and N2O reductase nosZ determines N2O emission from CW. Hence, the selection of nitrate-loving plants will play an important role in inhibiting N2O emission from CW.

Graphene's Role in Emerging Trends of Capacitive Energy Storage.

Technological breakthroughs in energy storage are being driven by the development of next-generation supercapacitors with favorable features besides high-power density and cycling stability. In this innovation, graphene and its derived materials play an active role. Here, the research status of graphene supercapacitors is analyzed. Recent progress is outlined in graphene assembly, exfoliation, and processing techniques. In addition, electrochemical and electrical attributes that are increasingly valued in next-generation supercapacitors are highlighted along with a summary of the latest research addressing chemical modification of graphene and its derivatives for future supercapacitors. The challenges and solutions discussed in the review hopefully will shed light on the commercialization of graphene and a broader genre of 2D materials in energy storage applications.

Interactive effects between cadmium stabilized by palygorskite and mobilized by siderophores from Pseudomonas fluorescens.

The application of palygorskite (PAL) for potentially toxic trace elements (Cd2+, Ni2+, etc.) remediation in polluted soil can substantially reduce the bioavailability and toxicity of these hazard materials. However, the secretion of organic acids and siderophores by microorganisms might result in the re-mobilization of cadmium (Cd) in PAL-bound forms (PAL-Cd). In this study, the interactive effects between Cd stabilized by PAL and mobilized by siderophores from Pseudomonas fluorescens were performed with four flask-shaking experimental treatments, namely, strain with or without an ability of siderophores production respectively associated with or without PAL-Cd. The GC-MS and UHPLC-MS test methods were used to analyze the concentrations of metabolites. Results showed that the Cd mobilized by strain with siderophores production was 22.1% higher than that of strain without the ability of siderophores production (p < 0.05). The mobilization of Cd in PAL in turn significantly reduced the siderophores production of Pseudomonas fluorescens by 25.1% (p < 0.05). The numbers of metabolites significantly up-regulated and down-regulated were 9 and 22 in strain groups with PAL-Cd addition compared with the groups without PAL-Cd, respectively. Metabolomics analysis revealed that the mobilized Cd affects the signal transduction pathway and primary metabolic processes, reduces the metabolic capacity of pentose phosphate pathway, glycolysis and tricarboxylic acid cycle pathway. These changes inhibit the ability of strain to biosynthesize amino acids during the mobilization processes, further reducing the capacity of Pseudomonas fluorescens to produce siderophores. This study provides a useful information on how to select soil Cd-stabilizing materials in a targeted manner and how to avoid Cd re-mobilization by siderophores.

Staging Surgery for The Treatment of Aortic Arch Aneurysm Combined with Aberrant Bilateral Subclavian Artery, Persistent Left Superior Vena Cava and Airway Compression: A Case Report.

BACKGROUND: To describe staging surgery for the treatment of a patient with aortic arch aneurysm combined with aberrant bilateral subclavian artery, persistent left superior vena cava (PLSVC), and airway compression. CASE REPORT: A 42-year-old female was hospitalized for aortic arch aneurysm involving aberrant bilateral subclavian artery, PLSVC, and airway compression. The patient's aneurysm was successfully treated by stage I surgery, including total aortic arch replacement and stented elephant trunk procedure and stage II surgery, including tracheal stenting and tracheotomy. Aortic CTA examination showed an unobstructed lumen and a good stent position without tracheal stent migration. Regular postoperative follow-up showed no complications, such as dyspnea, cough, and sputum, or other discomfort symptoms. CONCLUSIONS: Total aortic arch replacement, elephant trunk surgery, and second-stage tracheal stent surgery are effective and safe for the treatment of aortic arch aneurysm combined with aberrant bilateral subclavian artery, PLSVC, and airway compression.

Light-Activated Electron Transfer and Turnover in Ru-Modified Aldehyde Deformylating Oxygenases.

Conversion of biological molecules into fuels or other useful chemicals is an ongoing chemical challenge. One class of enzymes that has received attention for such applications is aldehyde deformylating oxygenase (ADO) enzymes. These enzymes convert aliphatic aldehydes to the alkanes and formate. In this work, we prepared and investigated ADO enzymes modified with RuII(tris-diimine) photosensitizers as a starting point for probing intramolecular electron transfer events. Three variants were prepared, with RuII-modification at the wild type (WT) residue C70, at the R62C site in one mutant ADO, and at both C62 and C70 in a second mutant ADO protein. The single-site modification of WT ADO at C70 using a cysteine-reactive label is an important observation and opens a way forward for new studies of electron flow, mechanism, and redox catalysis in ADO. These Ru-ADO constructs can perform the ADO catalytic cycle in the presence of light and a sacrificial reductant. In this work, the Ru photosensitizer serves as a tethered, artificial reductase that promotes turnover of aldehyde substrates with different carbon chain lengths. Peroxide side products were detected for shorter chain aldehydes, concomitant with less productive turnover. Analysis using semiclassical electron transfer theory supports proposals for hopping pathway for electron flow in WT ADO and in our new Ru-ADO proteins.

Effects of freshwater leaching on potential bioavailability of heavy metals in tidal flat soils.

Leaching experiments were conducted to investigate the effects of desalination levels and sediment depths on potential bioavailability of heavy metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in tidal flat soils. The data showed that both the desalination levels (p < 0.001) and soil depths (p < 0.001) had significant effects on the concentrations of acid-volatile sulfide (AVS). AVS concentrations generally exhibited increasing trends with an increase in depth and decreasing trends with enhanced desalination levels. The desalination levels had significant (p < 0.05) effects on the concentrations of simultaneously extracted metal (SEM; Cd, Cr, Cu, Fe, Mn, Pb, and Zn). Moreover, the concentrations of SEM (Cd, Cr, Cu, Fe, Mn, Pb, and Zn) generally tended to decrease with an increase in the desalination level. The desalination treatment significantly reduced the ratios of SEM/AVS compared with control. However, the ratios of SEM/AVS increased with enhanced desalination levels in treatments. Results reveal that low desalination treatment is better for reducing toxicity to benthic organisms than high desalination treatment. Since these reclaimed tidal flats with low desalinisation are suitable for saline water aquaculture, transforming the present land use of reclaimed tidal flats from fresh water aquaculture into saline water aquaculture may reduce health risk of heavy metals remained in sediments. These results will also contribute to our understanding of the dynamic behavior of heavy metals in the reclamation of tidal flats during leaching and the role of the ratio of SEM/AVS predictions on assessing the ecological risks of reclaimed tidal flats.

[Comparative study on effects of blood enriching on mouse model of blood deficiency syndrome induced by cyclophosphamide of albiflorin, paeoniflorin on levels of GM-CSF, IL-3 and TNF-α].

OBJECTIVE: To compare the effects and mechanism of blood enriching on mouse model of blood deficiency syndrome induced by cyclophosphamide of albiflorin and paeoniflorin. METHOD: Albiflorin and paeoniflorin were determined by using animal models of blood deficiency syndrome induced by cyclophosphamide. The amount of WBC, RBC, HGB, index of thymus gland and spleen, and the changes of GM-CSF, IL-3 and TNF-α in serum were detected after the treatment. RESULT: Compared with the model group, the amount of WBC in the group of 30 mg x kg(-1) albiflorin and 30 mg x kg(-1) paeoniflorin were increased obviously (P < 0.01). The amount of RBC in the group of 30 mg x kg(-1) albiflorin and 30 mg x kg(-1) paeoniflorin were increased obviously (P < 0.01, P < 0.001), which did not had a significant difference compared with the same dose. The index of thymus gland in the group of 30 mg x kg(-1) albiflorin was superior to the model group (P < 0.01), the difference was significant compared with the same dose of paeoniflorin (P < 0.05). The GM-CSF in serum in all groups of 30 mg x kg(-1) albiflorin, 15 mg x kg(-1) albiflorin, 30 mg x kg(-1) paeoniflorin and 15 mg x kg(-1) paeoniflorin increased obviously (P < 0.01, P < 0.05, P < 0.01, P < 0.05); The IL-3 in serum in both group of 30 mg x kg(-1) albiflorin and 30 mg x kg(-1) paeoniflorin also increased (P < 0.001). The content of TNF-α in group of 30 mg x kg(-1) albiflorin and 30 mg x kg(-1) paeoniflorin were reduced (P < 0.01), which showed the obvious difference compared with the same dose group (P < 0.01). CONCLUSION: Albiflorin had the effect of blood enriching by regulating the immune function, same with the paeoniflorin. The probable mechanism of nourishing blood and liver of Paeoniae Radix Alba was not only the better effect of adjusting the content of TNF-α, but also might act synergistically with paeoniflorin.

Identification of heavy metal sources in the reclaimed farmland soils of the pearl river estuary in China using a multivariate geostatistical approach.

Heavy metals in the reclaimed farmland soils of the Pearl River Estuary in China have attracted much attention because of the health risk posed to local residents. The identification of heavy metal sources in these soils is necessary to reduce their health risk. Reclaimed farmland soil samples were collected from 144 sites in the Pearl River Estuary and the contents of heavy metals (Cd, Pb, Cr, Ni, Cu, and Zn) were determined. All these heavy metals showed concentrations substantially higher than their background values, indicating possible anthropogenic pollution. The results of a multivariate geostatistical method demonstrate that grouped Cd, Cr, and Cu were mainly controlled by chemical fertilizers. Grouped Pb and Zn were the most severely impacted by atmospheric deposition from Guangzhou and Foshan, and Ni was primarily impacted by electroplating factories' wastewater discharge.

[Protective effect of Acai berries on chronic alcoholic hepatic injury in rats and their effect on inflammatory cytokines].

OBJECTIVE: To study the protective effect of Acai berries(Euterpe oleraceae) on chronic alcoholic hepatic injury in rats and their mechanism. METHOD: Wistar rats were fed for 1 week and randomly divided into blank group, model group, Dongbao Gantai group, Acai 1.6, 0.8, 0.4 g . kg-1 groups. The blank group was given distilled water, and the other groups were orally given 56% white spirit (Erguotou) for eight weeks at the dosages of 8 mL . kg-1 in the 1st week, which increased by 0.1 mL week by week till to 15 mL . kg-1, in order to establish the chronic hepatic injury model, and observe the effect of Acai berry freeze-dried powder on hepatocyte membrane permeability, liver lipid peroxidation, changes in inflammatory cytokines and pathological changes in hepatocytes. RESULT: Acai berries could significantly reduce serum ALT and AST(P<0.05), MDA(P<0.05), TG(P<0.05) and serum TNF-α and IL-6(P <0.05) and increase GSH and SOD(P <0.05). According to liver histopathological observation, livers in the model group were dominated by steatosis, some livers suffered spotty necrosis and inflammatory cell infiltration; The positive drug and Acai groups showed different changes in pathologic changes in rat livers. CONCLUSION: Acai berries show s specific protective effect on alcoholic hepatic injury. Its mechanism may be correlated with the inhibition of such inflammatory factors as TNF-α and IL-6.

[Determination of ß-sitosterol and total sterols content and antioxidant activity of oil in acai (Euterpe oleracea)].

In order to establish a method for the determination of the sterols of the oil in the freeze-dried acai (Euterpe oleracea Mart.) and to evaluate its antioxidant activities, a saponification/extraction procedure and high performance liquid chromatography (HPLC) analysis method were developed and validated for the analysis of phytosterols in PEE (Petroleum ether extract). Separation was achieved on a Purosper STAR LP C18 column with a binary, gradient solvent system of acetonitrile and isopropanol. Evaporative light scattering detection (ELSD) was used to quantify ß-sitosterol and the total sterols. Peak identification was verified by retention times and spikes with external standards. Standard curves were constructed (r = 0.999 2) to allow for sample quantification. Recovery of the saponification and extraction was demonstrated via analysis of spiked samples. The highest content of total sterols is ß-sitosterol. The antioxidant activities of the extracts were evaluated using the total oxyradical scavenging capacity assay (TOSC assay). The result showed that the PEE exhibited significant antioxidant properties, sample concentration and the antioxidant capacity had a certain relevance.

[Study on blood enriching effects of γ-ray radiation of paeoniflorin and albiflorin on mouse model of blood deficiency].

OBJECTIVE: To study the blood enriching effects of Paeoniae Radix Rubra and Paeoniae Radix Alba, paeoniflorin and albiflorin on mouse model of blood deficiency caused by γ-ray radiation. METHOD: Build mouse model of blood deficiency induced by γ-ray radiation. Paeoniae Radix Rubra and Paeoniae Radix Alba were given during modeling. The amount of WBC was detected af- ter the treatment. Based on the result of WBC and paeoniflorin content, albiflorin content in Paeoniae Radix Rubra and Paeoniae Radix Alba, the same model and the same method were used to comparatively study the effect of blood enriching of paeoniflorin and albiflorin. RESULT: On the 7th day, the amount of WBC in model mice treated with 2 g x kg(-1) Paeoniae Radix Alba and 2 g x kg(-1) Paeoniae Radix Rubra significantly increased compared with that of model group (P < 0.05). In another experiment with the same model, the amount of WBC in model mice treated with 120 mg x kg(-1) paeoflorin and 120 mg x kg(-1) albiflorin significantly increased (P < 0.05) compared with that of model group on the 7th day. On the 10th day, the amount of WBC in rats treated with 120 mg x kg(-1) paeoflorin increased significantly (P < 0.05) compared with that of model group. Compared with the same dose of paeoniflorin, the amount of WBC in mice treated with albiflorin had no significant difference. CONCLUSION: All Paeoniae Radix Alba, Paeoniae Radix Rubra, paeoniflorin and al- biflorin can raise the amount of WBC and have the effect of enriching blood induced by radiation, while paeoniflorin and albiflorin have a similar result in this model. The result indicated that both paeoniflorin and albiflorin are effective constituents in Paeoniae Radix Alba, and paeoniflorin work as the common effective constituent in both Paeoniae Radix Rubra and Paeoniae Radix Alba.

Immunopeptides: immunomodulatory strategies and prospects for ocular immunity applications.

Immunopeptides have low toxicity, low immunogenicity and targeting, and broad application prospects in drug delivery and assembly, which are diverse in application strategies and drug combinations. Immunopeptides are particularly important for regulating ocular immune homeostasis, as the eye is an immune-privileged organ. Immunopeptides have advantages in adaptive immunity and innate immunity, treating eye immune-related diseases by regulating T cells, B cells, immune checkpoints, and cytokines. This article summarizes the application strategies of immunopeptides in innate immunity and adaptive immunity, including autoimmunity, infection, vaccine strategies, and tumors. Furthermore, it focuses on the mechanisms of immunopeptides in mediating ocular immunity (autoimmune diseases, inflammatory storms, and tumors). Moreover, it reviews immunopeptides' application strategies and the therapeutic potential of immunopeptides in the eye. We expect the immune peptide to get attention in treating eye diseases and to provide a direction for eye disease immune peptide research.

Effect of Deposition Pressure and Temperature on Tungsten Thin-Film Heater for Phase-Change Switch Applications.

Tungsten (W) film is increasingly utilized in various microheater applications due to its numerous advantages. These advantages include a high melting point, positive constant temperature coefficient of resistance (TCR), good mechanical stability, and compatibility with semiconductor processes. In this paper, deposition parameters for enhancing the properties of W film were investigated, and an optimized microheater was fabricated. It was found that the deposition temperature and pressure can modify the TCR to be negative or positive and the crystalline phase of W films to be alpha phases or mixed with beta phases. A W film deposited under 650 °C with a pressure of 1 pa has a positive TCR and pure alpha phase crystalline structure. We applied this optimized W film as a microheater in an RF phase-change switch (RFPCS), and the maximum voltage of the optimized W microheater increased by at least 48% in this work. By optimizing the microheater, the phase-change switch can be successfully actuated in both on and off states, demonstrated by the Raman results of the phase-change material. A voltage pulse of 20 V/200 ns was enough to turn the switch off with MΩ, and 11 V/3 µs could turn the switch on with 138 Ω. The optimized microheater and device can cycle 500 times without failure. The insertion loss and isolation of the device at 20 GHz was 1.0 dB and 22 dB.

A Review on Material Selection Benchmarking in GeTe-Based RF Phase-Change Switches for Each Layer.

The global demand for radio frequency (RF) modules and components has grown exponentially in recent decades. RF switches are the essential unit in RF front-end and reconfigurable systems leading to the rapid development of novel and advanced switch technology. Germanium telluride (GeTe), as one of the Chalcogenide phase-change materials, has been applied as an RF switch due to its low insertion loss, high isolation, fast switching speed, and low power consumption in recent years. In this review, an in-depth exploration of GeTe film characterization is presented, followed by a comparison of the device structure of directly heated and indirectly heated RF phase-change switches (RFPCSs). Focusing on the prototypical structure of indirectly heated RFPCSs as the reference, the intrinsic properties of each material layer and the rationale behind the material selection is analyzed. Furthermore, the design size of each material layer of the device and its subsequent RF performance are summarized. Finally, we cast our gaze toward the promising future prospects of RFPCS technology.