Investigation of the 6H-SiC (0001) surface by AFM

Micropipe and step structures on 6H-SiC （0001） surface were investigated by an atomic force microscopy （AFM）. On the facet,all micropipes examined are the origins of spiral steps,indicating that dislocations intersect the surface at these points. Micropipes are empty-core super-dislocations as originally described by Frank. The micropipe radius increases with the square of the dislocation Burgers vector. From the center to the periphery,step structures change with different surface inclinations. Regular step is observed within the central faceted area. Step bunching and atomically rough surfaces are observed within the peripheral convex area. If the inclination with respect to the （0001） plane is large enough,step bunching of 15R-SiC can be observed.

Effective Increase of Crystal Area during Sublimation Growth of 6H-SiC by Using the Cone-shaped Baffle

A novel design of crucible is proposed in this paper for the growth of SiC crystals. The relation between grown crystal shape and temperature distribution in a growth chamber was discussed. It is pointed out that the crystal shape had a close relationship with temperature distribution. The calculations suggested that the radial temperature field of the growing crystal became homogenous by setting up the cone-shaped baffle in the growth chamber. By modifying the crucible design and temperature distribution in the growth chamber, it is possible to enhance the enlargement of crystal, and also possible to keep grown surface flat.

The successful treatment for cardiac tamponade during radiofrequency ablation of hepatocellular carcinoma

To the Editor:Hepatocellular carcinoma(HCC)is the second most common cause of cancer-related death worldwide[1].Repeated liver resection remains a valid and safe curative therapy option for recurrent HCC in a minority of patients,because of multifocal intrahepatic or extra-hepatic recurrence and tumors in unresectable locations[2].HCC nodules less than 3 cm located in the hepatic dome beneath the diaphragm may represent one of the most difficult sites for resection[3].Therefore,some local invasive therapies,such as radiofrequency ablation(RFA),microwave ablation,transarterial chemoembolization(TACE)and laser hyperthermia,have been developed and applied in clinical HCC treatment[4].RFA has high frequency energy which heats the surrounding tissues and causes severe complications such as acute massive hemorrhage,thermal injury to viscera,pneumothorax and cardiac tamponade[5].

Disulfiram:A novel repurposed drug for cancer therapy

Cancer is a major global health issue.Effective therapeutic strategies can prolong patients’survival and reduce the costs of treatment.Drug repurposing,which identifies new therapeutic uses for approved drugs,is a promising approach with the advantages of reducing research costs,shortening development time,and increasing efficiency and safety.Disulfiram(DSF),a Food and Drug Administration(FDA)-approved drug used to treat chronic alcoholism,has a great potential as an anticancer drug by targeting diverse human malignancies.Several studies show the antitumor effects of DSF,particularly the combination of DSF and copper(DSF/Cu),on a wide range of cancers such as glioblastoma(GBM),breast cancer,liver cancer,pancreatic cancer,and melanoma.In this review,we summarize the antitumor mechanisms of DSF/Cu,including induction of intracellular reactive oxygen species(ROS)and various cell death signaling pathways,and inhibition of proteasome activity,as well as inhibition of nuclear factor-kappa B(NF-κB)signaling.Furthermore,we highlight the ability of DSF/Cu to target cancer stem cells(CSCs),which provides a new approach to prevent tumor recurrence and metastasis.Strikingly,DSF/Cu inhibits several molecular targets associated with drug resistance,and therefore it is becoming a novel option to increase the sensitivity of chemo-resistant and radio-resistant patients.Studies of DSF/Cu may shed light on its improved application to clinical tumor treatment.

Synthesis and molecular recognition characteristics of a tetrapodal benzene cage

In this contribution,we describe the preparation and recognition characteristics of a novel tetrapodal benzene cage(1).The cage can express a wide recognition range without losing selectivity for the object of appropriate size and functional groups.The key to obtaining the desired structural isomer of 1 is the synthesis and isolation of the o-bis(bromomethyl)benzene precursor(5).Three distinct guests,F^(−)(ex-tremely small size),d-lactate(appropriate size)and l-Asp(branched shape),were selected as examples to demonstrate the recognition characteristics of 1.By NMR titration studies,they all expressed good binding affinity(K>10^(5) L/mol)in competitive medium(10%DMSO/THF),indicating that 1 has a wide recognition scope.The highest binding constant was observed for d-lactate,revealing that 1 has good selectivity for d-lactate versus F^(−)and L-Asp.Moreover,the NMR titration study of F^(−)in DMSO indicates 1 can achieve different binding modes(1:1 and 2:1 guest-host)for small-sized guests,which allows for the further development of binary binding properties and thereafter applications in the field of catalysis.

Important mesoscale phenomena in gas phase fluidized bed ethylene polymerization

Gas phase fluidized bed processes have been widely applied to polyethylene production.In these processes,the flow,mass transfer,and reaction rate on the microscale and macroscale are strongly coupled because of the multiphase and multiscale nature of the fluidization system.Understanding mesoscale phenomena is therefore essential to the quantitative translation of the knowledge obtained from the microscale to the macroscale.This paper reviews the development of ethylene polymerization gas phase processes while focussing on studies regarding mesoscale phenomena.These include experimental characterizations,mathematical modelling and control strategies.Trends and future developments in this field are also discussed.

Plasma biomarkers and plaque strain predict long-term cardiovascular events in patients with acute coronary syndrome

To test whether circulating and intracoronary biomarkers and coronary plaque strain have additive values to Global Registry of Acute Coronary Events(GRACE) score for predicting long-term cardiovascular events in ACS patients. One hundred ACS patients were enrolled and the GRACE score and plasma levels and intracoronary gradients of a number of biomarkers were measured. Coronary plaque burden and morphology in non-critical stenotic plaques were determined by intravascular ultrasound(IVUS) technique, and the maximal shear strain(SSmax) and maximal area strain(ASmax) were determined by intravascular ultrasound elastography(IVUSE) technique. Patients were followed for cardiovascular events and the predictive values of clinical characteristics, plasma biomarkers and plaque parameters were compared with GRACE score, and the incremental values of these measurements to the GRACE score were assessed. GRACE score, plasma biomarkers and plaque strain were independent predictors of cardiovascular events. Combination of GRACE score, plasma biomarkers and plaque strains significantly improved the predictive value of the GRACE score alone with the receiver-operating characteristic area increased from0.457 to 0.667(P=0.014). The combination of circulating and intracoronary biomarkers, plaque strain and GRACE score provides a better predictive tool than GRACE score alone in patients with ACS.

Research progress of large size SiC single crystal materials and devices

SiC semiconductor is the focus of recent international research.It is also an important raw material for China to achieve carbon emission peak and carbon neutrality.After nearly 20 years of research and development,we focus on the three types SiC crystals,n-type,p-type and semi-insulating,indicating the development of Shandong University for crystal growth.And defects control,electrical property,atomic polishing,and corresponding device authentication all obtain great progress.Total dislocation density of 6-inch n-type substrates decreases to 2307 cm^(-2),where BPD(Basal Plane Dislocation)lowers to 333 cm^(-2) and TSD(Threading Screw Dislocation)19 cm^(-2).The full width at half maximum(FWHM)(0004)rocking curves is only 14.4 arcsec.The resistivity reaches more than 1E+12Ω·cm for semi-insulating SiC and lower than 20 mΩ·cm for n-type SiC.The impurity concentrations in 6-inch high-purity semi-insulating(HPSI)SiC crystals reach extreme low levels.The devices made of various substrate materials have good performance.

Using coupling slabs to tailor surface-acoustic-wave band structures in phononic crystals consisting of pillars attached to elastic substrates

The propagation of surface acoustic waves(SAWs) in two-dimensional phononic crystals(PnCs) with and without coupling-enhancement slabs was theoretically investigated using a three-dimensional finite element method.Different piezoelectric substrates,for example,lithium niobate(LiNbO_3),gallium nitride(GaN),and aluminium nitride(A1N),were taken into account.Compared to the PnCs without coupling-enhancement slabs,the coupling between each pillar and its nearest neighbor was largely enhanced in the presence of slabs.The bandwidth of the first directional band gap increased markedly compared with its initial value for the PnCs without a slab(within square symmetry).In addition,with increasing thicknesses of the slabs bonded between neighboring pillars,the first directional band-gap and second directional band gap of the PnCs tend to merge.Therefore,the structure with coupling-enhancement slabs can be used as an excellent electrical band elimination filter for most electro-SAW devices,offering a new strategy to realize chip-scale applications in electroacoustic signal processing,optoacoustic modulation,and even SAW microfluidic devices.

lon migration suppression mechanism via 4-sulfobenzoic acid monopotassium salt for 22.7%stable perovskite solar cells

The deep-level traps at grain boundaries(GBs)and halide ion migration are quite challenging for further enhancement of the stability and efficiency of perovskite solar cells(PSCs)as well as for the elimination of notorious hysteresis.Herein,we report a large-sized strongly coordinated organic anion GB anchoring strategy for suppressing ion migration and passivating defects in planar PSCs.The practical implementation of this strategy involves the incorporation of potassium salts containing a large-sized organic counter anion(4-sulfobenzoic acid monopotassium salt,SAMS)into the perovskite precursor.It has been found that anions within SAMS can be firmly anchored at GBs due to the strong coordination interaction between C=O and/or S=O at both ends of bulky anion and undercoordinated Pb^(2+)and/or halide vacancies,along with the hydrogen bond between–OH and formamidinium.SAMS can not only passivate shallowlevel defects but also cause more effective passivation of the deep-level defects.The GB manipulation strategy results in a reduced defect density,an increased carrier lifetime as well as suppressed ion migration,which in turn contributed to enhanced efficiency and stability of PSCs together with a thorough elimination of hysteresis.As a result,the SAMSmodified device with an outstanding fill factor of 0.84 delivers a significant improvement in efficiency(22.7%)in comparison with the control device(20.3%).The unencapsulated modified device demonstrates only little degradation after 1320 h at 60℃.

In Situ Fabrication of Superfine Perovskite Composite Nanofibers with Ultrahigh Stability by One‑Step Electrospinning Toward White Light‑Emitting Diode

All-inorganic CsPbX_(3)(X=Cl,Br,I)perovskite nanocrystals(NCs)are emerging as promising candidate materials for optoelectronic devices due to their splendid optical and electrical properties.However,the intrinsic instability greatly limits their practical application.Herein,a feasible strategy is proposed for fabricating highly stable and luminescent CsPbBr_(3)@PVDF-HFP/PS nanofibers by combining one-step electrospinning method with 1H,1H,2H,2H-perfluorodecyltrimethoxysi-lane(PFDTMS)-assisted post-treatment.The bright-emitting CsPbBr_(3) NCs can be effectively encapsulated within polymer nanofibers,which exhibit ultrafine diameter of only 88.1±2.8 nm and high photoluminescence quantum yield(PLQY)of 87.9%via rationally optimizing the electrospinning parameters,concentration of perovskite precursors and ligands.Most importantly,the superhydrophobic surface structures of nanofibers are formed by the hydrolysis and condensation of PFDTMS under moist environment.Benefiting from the double effective protection of polymer matrices and hydrophobic PFDTMS oligomers against moisture erosion,the CsPbBr_(3)@PVDF-HFP/PS nanofibers present an obviously improved stability,which can retain 90%initial PL intensity after water immersion for 70 days.Furthermore,an efficient white light-emitting diode with wide color gamut covering 117%of National Television System Committee(NTSC)standard is successfully fabricated based on the composite nanofiber membranes,suggesting their promising prospect for solid-state lighting and display applications.

Hierarchical Porous Patterns of n-type 6H-SiC Crystals via Photoelectrochemical Etching

Hierarchical porous patterns have been fabricated on the C face, Si face, and cross section of n-type 6H-SiC crystal via photo-electrochemical etching using HF/C2H5OH and HF/H2O2 as electrolytes. The porous layer displayed multiple and multiscale microstructures on different faces, including stalactite-like, sponge-like and dendritic porous structures on C face, echinoid micro-patterns on Si face, and columnar and keel-shaped micro-patterns on the cross section. The formation of hierarchical porous pattern is ascribed to the dynamic competition balance between the electrochemical oxidation rate and the oxide removal rate. It was found that increasing the ionic strength of the electrolyte can obviously disturb the surface morphology of the porous SiC during the photo-electrochemical etching. Possible mechanisms for selective etching were further discussed.

Superior single-mode lasing in a self-assembly CsPbX3 microcavity over an ultrawide pumping wavelength range

All-inorganic perovskite micro/nanolasers are emerging as a class of miniaturized coherent photonic sources for many potential applications,such as optical communication,computing,and imaging,owing to their ultracompact sizes,highly localized coherent output,and broadband wavelength tunability.However,to achieve singlemode laser emission in the microscale perovskite cavity is still challenging.Herein,we report unprecedented single-mode laser operations at room temperature in self-assembly Cs Pb X3 microcavities over an ultrawide pumping wavelength range of 400–2300 nm,covering one-to five-photon absorption processes.The superior frequency down-and upconversion single-mode lasing manifests high multiphoton absorption efficiency and excellent optical gain from the electron–hole plasma state in the perovskite microcavities.Through direct compositional modulation,the wavelength of a single-mode Cs Pb X3 microlaser can be continuously tuned from blue-violet to green(427–543 nm).The laser emission remains stable and robust after long-term high-intensity excitation for over 12 h(up to 4.3×107 excitation cycles)in the ambient atmosphere.Moreover,the pump-wavelength dependence of the threshold,as well as the detailed lasing dynamics such as the gain-switching and electron–hole plasma mechanisms,are systematically investigated to shed insight into the more fundamental issues of the lasing processes in Cs Pb X3 perovskite microcavities.

PFKL,a novel regulatory node for NOX2-dependent oxidative burst and NETosis

Neutrophils are predominant leukocytes in the circulation,which are essential for killing invading pathogens via the activation of effector responses and the production of reactive oxygen species(ROS),also named as"oxidative burst."When infected,activated neutrophils fight bacteria,fungi,and viruses through oxidative burst,phagocytosis,degranulation,and the production of neutrophil extracellular traps(NETs)in a neutrophil death process named as"NETosis"(Mutua and Gershwin,2021).

Anomalous Resistivity in Vanadium-Doped Semi-Insulating 4H-SiC Wafers

The resistivities of vanadium-doped semi-insulating 4H-SiC wafers were measured by a contactless resistivity measurement system. Anomalous resistivity was found in semi-insulating 4H-SiC wafer. Raman spectra of semi-insulating4H-SiC wafer indicated that the anomalous resistivity was caused by polytype inclusion. Based on the activation energies of different SiC polytypes calculated from resistivity versus temperature data measured by COREMA-VT, the resistivities in the vanadium-doped semi-insulating 4H-SiC wafer with 6H polytype inclusion were calculated. The calculated resistivities are quite consistent with the measured resistivities. Furthermore, the compensation mechanism for the formation of anomalous resistivity was proposed.

Detection of surface defects and subsurface defects of polished optics with multisensor image fusion

Surface defects(SDs)and subsurface defects(SSDs)are the key factors decreasing the laser damage threshold of optics.Due to the spatially stacked structure,accurately detecting and distinguishing them has become a major challenge.Herein a detection method for SDs and SSDs with multisensor image fusion is proposed.The optics is illuminated by a laser under dark field condition,and the defects are excited to gener-ate scattering and fluorescence lights,which are received by two image sensors in a wide-field microscope.With the modified algorithms of image registration and feature-level fusion,different types of defects are identified and extracted from the scattering and fluorescence images.Experiments show that two imaging modes can be realized simultaneously by multisensor image fusion,and HF etching verifies that SDs and SSDs of polished optics can be accurately distinguished.This method provides a more targeted reference for the evaluation and control of the defects of optics,and exhibits potential in the application of material surface research.