Preparation and performance of a CsI scintillation screen with a double-period structure based on an oxidized silicon micropore array template.

A structured double-period CsI scintillation screen was successfully developed to improve its detection efficiency based on an oxidized silicon micropore array template with a period value on the order of micro-scale. The structure comprises a main structure along with a sub-structure. The main structure with a period of 8 µm was arranged in a square array consisting of square columnar scintillator units. The micropore walls between the main structure units were purposely fabricated from a SiO2-Si-SiO2 layered structure. The pore walls in commonly used single-structure with a period of 4 µm use the same layered structure composition to obtain a fair comparison. The thickness of both Si and the SiO2 layers was around 0.4 µm. The unique feature of the double structure lies in the even separation of each unit within the main structure into four square columnar scintillator sub-units. These four sub-units within each sub-structure were isolated solely by SiO2 layers with a thickness of approximately 0.8 µm. As a result, the X-ray-induced optical luminescence intensity of the double-structure screen exhibited a 31% increase compared to the corresponding single-structure scintillation screen. In X-ray imaging, a spatial resolution of 109 lp/mm was achieved, which closely matched the results obtained with the single-structure CsI screen. Furthermore, the detective quantum efficiency also displayed a notable improvement.

Optimization of SiO2 reflective layer thickness for improving the performance of structured CsI scintillation screen based on oxidized Si micropore array template in X-ray imaging.

Structured scintillation screen based on oxidized Si micropore array template can effectively improve the spatial resolution of X-ray imaging. The purpose of this study is to investigate the effect of SiO2 layer thickness on the light guide and X-ray imaging performance of CsI scintillation screen when the structural period is as small as microns. Cylindrical micropores with a period of 4.3 µm, an average diameter of 3.3 µm and a depth of about 40 µm were prepared in Si wafers. SiO2 layer was formed on the pore walls after thermal oxidation. Increasing SiO2 layer thickness would be beneficial to the propagation of scintillation light along the cylindrical channels. What was not previously anticipated was that the pore size gradually shrank as the SiO2 layer thickened. The pore shrinkage would reduce the filling rate of CsI in the templates and thus would reduce the production of scintillation light. The structured CsI scintillation screens with different SiO2 layer thicknesses were fabricated by filling CsI scintillator into the oxidized silicon micropore array template. The morphology, crystallinity, X-ray excited optical luminescence, and X-ray imaging performance of the screens were studied. The results show that the spatial resolutions of X-ray images measured using the structured CsI scintillation screens with different SiO2 layer thicknesses are close to each other, and they are all about 110 lp/mm. However, the X-ray excited optical luminescence of the screen and detective quantum efficiency of X-ray imaging vary with the thickness of the SiO2 layer. The optimal thickness is about 350 nm.

Application of Scanning Tunneling Microscopy and Spectroscopy in the Studies of Colloidal Quantum Qots.

Colloidal quantum dots display remarkable optical and electrical characteristics with the potential for extensive applications in contemporary nanotechnology. As an ideal instrument for examining surface topography and local density of states (LDOS) at an atomic scale, scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) has become indispensable approaches to gain better understanding of their physical properties. This article presents a comprehensive review of the research advancements in measuring the electronic orbits and corresponding energy levels of colloidal quantum dots in various systems using STM and STS. The first three sections introduce the basic principles of colloidal quantum dots synthesis and the fundamental methodology of STM research on quantum dots. The fourth section explores the latest progress in the application of STM for colloidal quantum dot studies. Finally, a summary and prospective is presented.

Desilylative Coupling Involving C(sp2)-Si Bond Cleavage on Metal Surfaces.

Desilylative coupling involving C-Si bond cleavage has emerged as one of the most important synthetic strategies for carbon-carbon/heteroatom bond formation in solution chemistry. However, in on-surface chemistry, C-Si bond cleavage remains a synthetic challenge. Here, we report the implementation of C(sp2)-Si bond cleavage and subsequent C-C bond formation on metal surfaces. The combination of scanning tunneling microscopy and density functional theory calculation successfully reveals that the incorporation of the C-Br group on the arylsilanes is critical to the success of this desilylative coupling reaction on metal surfaces. Our study represents a promising approach for the removal of protecting silyl groups in on-surface chemistry.

Surface Characterization of the Solution-Processed Organic-Inorganic Hybrid Perovskite Thin Films.

The surface properties of organic-inorganic hybrid perovskites can strongly affect the efficiency and stability of corresponding devices. Even though different surface passivation methods are developed, the microscopic structures of solution-processed perovskite film surfaces are not systematically studied. This study uses low-temperature scanning tunneling microscopy to study the organic-inorganic hybrid perovskite thin films, MA0.4 FA0.6 PbI3 and MAPbI3 , synthesized by the spin-coating method. Flat surface structures, atomic steps, and crystal grain boundaries are resolved at an atomic resolution. The surface imperfections are also characterized, as well as the dominant defects. Simulations on different types of iodine vacancy configurations are performed by density functional theory calculations. In addition, it is observed that the surface iodine lattice structure is unstable during scanning. Tip scanning can also cause the vertical migration of surface iodine ions. The measurements provide the direct visualizations of the surface imperfections of the solution-processed perovskite films. They are essential for understanding the surface-related optoelectronic effects and rationally designing more efficient surface passivation methods.

Influence of the thickness of a SiO2 reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging.

To obtain better light guidance and optical isolation effects under a limited microcolumn wall thickness, the influence of the thickness of a SiO2 reflective layer on the performance of a structured CsI(Tl) scintillation screen based on an oxidized Si micropore array template in X-ray imaging was simulated. The results show that the SiO2 reflective layer should maintain a certain thickness to achieve good light-guide performance. However, if the template is entirely composed of SiO2, the light isolation performance of the microcolumn wall will be slightly worse. The results provide a basis for optimizing the thickness of SiO2 reflective layer.

Performance of a CsI(Tl) scintillation screen with a dual-periodic structure based on an oxidized silicon micropore array template in X-ray imaging.

To address the reduction in the detection efficiency of a structured CsI(Tl) scintillation screen when its structure period reaches the order of microns, a dual-periodic structure of the screen is proposed. The special feature of the dual structure is that each unit of the primary structure is divided equally into either four or nine square column-shaped scintillation sub-units. The sub-units are separated only by SiO2 layers to form a secondary structure. The results show that the performance of a dual-structure CsI(Tl) screen in X-ray imaging is much better than that of a corresponding single-structure screen.

Primary ectopic parasellar craniopharyngioma: a case report.

BACKGROUND: Craniopharyngioma (CP) is a slow-growing, benign tumor of the central nervous system located within the sellar and suprasellar regions. The tumor may extend from the suprasellar region to other areas. CPs are generally believed to originate from squamous remnants of an incompletely involuted craniopharyngeal duct that also develops from Rathke's pouch. Primary parasellar craniopharyngioma is a relatively rare tumor, and nasal endoscopy, computed tomography, and enhanced magnetic resonance imaging can be applied to better evaluate the invasiveness and characteristics of these tumors. CASE PRESENTATION: We report a case of right parasellar craniopharyngioma in a 49-year-old female patient with a 10-day history of dizziness and blurred vision. Preoperative imaging examination revealed right parasellar space-occupying lesions, and the patient underwent transnasal neuroendoscopic resection of the right parasellar space-occupying lesion. The postoperative pathological result confirmed craniopharyngioma. CONCLUSIONS: Primary ectopic parasellar craniopharyngioma is a relatively rare tumor, and preoperative imaging examination can assist in the evaluation of tumor characteristics. However, the final diagnosis continues to depend on the histopathological results.

Prenatal sevoflurane exposure causes abnormal development of the entorhinal cortex in rat offspring.

As a gamma-aminobutyric acid type A receptor agonist sevoflurane is a common general anesthetic used in anesthesia and affects the neural development in offspring. We hypothesized that sevoflurane could regulate interneurons via the neuregulin-1-epidermal growth factor receptor-4 (NRG1-ErbB4) pathway in the entorhinal cortex (ECT) of the middle pregnancy. Six female rats in middle pregnancy (14.5 days of pregnancy) were randomly and equally divided into sevoflurane (SeV) and control groups. The rats in the SeV group were exposed to 4% sevoflurane for 3 hours. The expression levels of NRG1 and ErbB4, parvalbumin (PV) and glutamic acid decarboxylase (GAD67), and N-methyl-D-aspartate receptor subunit 2A (NR2A) and subunit 2B (NR2B) in offspring were examined through immunohistochemistry. The pyramidal neurons in the ECT were examined via Golgi staining. The levels of NRG1 and ErbB4 were significantly decreased (P < 0.01) and the levels of PV and GAD67 (interneurons) were found to be decreased in the SeV group (P < 0.01). The level of NR2B was found to be increased while the level of NR2A being decreased in the SeV group (P < 0.01). The development of pyramidal neurons was abnormal in the SeV group (P < 0.05). Conclusively, prenatal sevoflurane exposure could lead to the disturbance of the interneurons by activating the NRG1-ErbB4 pathway and subsequently result in abnormal development of pyramidal neurons in middle pregnancy. Prenatal sevoflurane exposure in middle pregnancy could be potentially harmful to the neural development of rat offspring. This study may reveal a novel pathway in the influence mechanism of sevoflurane on rat offspring.

Prenatal sevoflurane exposure causes neuronal excitatory/inhibitory imbalance in the prefrontal cortex and neurofunctional abnormality in rats.

The balance of excitatory and inhibitory neurons in the central nervous system is critical for maintaining brain function and sevoflurane, a general anesthetic and an GABA receptor modulator, may change the balance of excitatory and inhibitory neurons in the cortex during early brain development. Herein, we investigated whether prenatal sevoflurane exposure (PSE) disturbs cortical neuronal development and brain function. Pregnant rats at the gestational day 14.5 were subjected to sevoflurane exposure at 3.0% for 3 h and their offspring were studied thereafter. We found a significant increase of parvalbumin-positive neurons, vesicular GABA transporter (VGAT) and GAD67 expression, and GABA neurotransmitter, and a significant decrease of vesicular glutamate transporter 1 (VGLUT1) expression and glutamate in the medial prefrontal cortex (mPFC) of offspring. Pyramidal neurons showed atrophy with shorter dendrites, less branches and lower spine density visualized by Golgi stain and a decrease of excitability with the increased miniature inhibitory postsynaptic current (mIPSC) frequency and amplitude, the decreased miniature excitatory postsynaptic current (mEPSC) frequency and excitation/inhibition (E/I) ratio using whole-cell recording in offspring. There was a significant increase of inhibitory synapse in the mPFC detected by electron microscopy. Furthermore, PSE animals showed hypo-excitatory phenotype including depression-like behaviors and learning deficits. Thus, our studies provide novel evidence that PSE causes the persisted imbalance of excitatory and inhibitory neurons in the mPFC, and this is very likely the mechanisms of the sevoflurane-induced brain functional abnormalities.

Influence of silicon wall thickness on the performance of structured CsI(Tl) scintillation screen based on oxidized silicon micropore array template in X-ray imaging.

The influence of silicon wall thickness on the performance of structured CsI(Tl) scintillation screen based on oxidized silicon micropore array template in X-ray imaging was simulated using Geant4 Monte Carlo simulation code in terms of light output (LO), modulation transfer function (MTF) and detective quantum efficiency (DQE). The results show that when the thickness of the silicon wall is less than 0.5 µm, the increase in the bottom light output (BLO) of the screen and the decrease in the spatial resolution of the X-ray imaging system using the screen become more significant as the thickness decreases. At low spatial frequency, the thicker the silicon wall, the lower the DQE. However, the DQE with a thick silicon wall can exceed the DQE with a thin silicon wall at high spatial frequency. All the results provide the quantitative relation between the silicon wall thickness of the structured CsI(Tl) scintillation screen and the quality of the X-ray imaging.

Dexmedetomidine attenuates spinal cord ischemia-reperfusion injury through both anti-inflammation and anti-apoptosis mechanisms in rabbits.

BACKGROUND: Dexmedetomidine (Dex) can improve neuronal viability and protect the spinal cord from ischemia-reperfusion (I/R) injury, but the underlying mechanisms are not fully understood. This study investigated the effects of dexmedetomidine on the toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NF-κB) inflammatory system and caspase-3 dependent apoptosis induced by spinal cord ischemia-reperfusion injury. METHODS: Twenty-four rabbits were divided into three groups: I/R, Dex (10 µg/kg/h prior to ischemia until reperfusion), and Sham. Abdominal aortic occlusion was carried out for 30 min in the I/R and Dex groups. Hindlimb motor function was assessed using the Tarlov scoring system for gait evaluation. Motor neuron survival and apoptosis in the ventral grey matter were assessed by haematoxylin-eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling staining. The expression and localisation of ionised calcium-binding adaptor molecule 1, TLR4, NF-κB and caspase-3 were assessed by immunoreactivity analysis. The levels of interleukin 1ß and tumour necrosis factor α were assessed using enzyme-linked immunosorbent assays. RESULTS: Perioperative treatment with dexmedetomidine was associated with a significant preservation of locomotor function following spinal cord ischemia-reperfusion injury with increased neuronal survival in the spinal cord compared to control. In addition, dexmedetomidine suppressed microglial activation, inhibited the TLR4-mediated NF-κB signalling pathway, and inhibited the caspase-3 dependent apoptosis. CONCLUSIONS: Dexmedetomidine confers neuroprotection against spinal cord ischemia-reperfusion injury through suppression of spinal cord inflammation and neuronal apoptosis. A reduction in microglial activation and inhibition of both the TLR4-mediated NF-κB signalling pathway and caspase-3 dependent apoptosis are implicated.

Development of ZnO-based nanorod arrays as scintillator layer for ultrafast and high-spatial-resolution X-ray imaging system.

Under excitation of high-energy and low-flux density of X-ray beam, a 1-µm system spatial resolution was initially achieved by using an 18-µm thickness ZnO nanorod array as the scintillator layer in X-ray imaging beamline at Shanghai Synchrotron Radiation Facility. The decay time measurements indicated the ultraviolet and visible emissions of the arrays were subnanosecond and nanosecond, respectively. Through hydrogen annealing treatment, the ultraviolet luminescence was intensively enhanced and the visible luminescence was remarkably suppressed simultaneously. In conclusion, it can be determined that the ZnO-based nanorod arrays are the decent candidates for applications in ultrafast and high-spatial-resolution X-ray imaging systems.

[Subclinical hypothyroidism and endocrine metabolic characteristics in women with polycystic ovary syndrome].

OBJECTIVE: To explore associations of subclinical hypothyroidism (SCH) with endocrine metabolic characteristics in women with polycystic ovary syndrome (PCOS).
 Methods: A total of 321 women who were newly diagnosed as PCOS were recruited from two endocrine outpatient clinics. The diagnosis of PCOS was established according to the 2003 Rotterdam consensus criteria. Thyroid function was examined by chemiluminescent immunoassay. Patients who had normal free thyroxine (FT4) were divided into different SCH subgroups according to two thyroid stimulating hormone (TSH) cutoff points (4.2 and 2.5 mU/L). Endocrine metabolic characteristics in different subgroups were compared and analyzed.
 Results: In PCOS women with normal FT4, the patients with TSH≥4.2 mU/L had higher prolactin (PRL), luteinizing hormone-to-follicle stimulating hormone ratio, and visceral adipose index (all P<0.05). There were trends toward an increase in triglyceride (P=0.085) and a decrease in high-density lipoprotein cholesterol (HDL-C) (P=0.060) in the patients with TSH≥4.2 mU/L compared with that in the patients with TSH<4.2 mU/L. Also in PCOS women with normal FT4, the patients with TSH≥2.5 mU/L had higher body mass index, PRL, triglyceride, visceral adipose index and lower HDL-C in comparison of that in the patients with TSH<2.5 mU/L (all P<0.05).
 Conclusion: SCH is associated with more severe endocrine abnormality, dyslipidemia, and visceral obesity in PCOS women. PCOS women with normal FT4 and endocrine metabolic characteristics are more prone to be different between the SCH group and the euthyroid group when setting 2.5 mU/L as a TSH cutoff for SCH, indicating that 2.5 mU/L is a good TSH cutoff for SCH in PCOS women.

A novel tool for tracing water sources of streamflow in a mixed land-use catchment.

Tracing water sources of streamflow in a mixed land-use catchment is critical for predicting pollutant emissions from various human activities to streams but remains a major challenge. A rain event based field monitoring study was conducted in the Jieliu catchment located in the hilly area of central Sichuan Province, southwest China. The ratio of the maximum fluorescence intensities (Fmax) of the two humic-like dissolved organic matter (DOM) components at excitation/emission wavelengths of 255 (315)/415 nm (component 1; C1) and 260 (375)/480 nm (component 2; C2) was proposed as a tracer for quantifying streamflow water sources. Satisfactory performance of using the Fmax(C1)/Fmax(C2) ratio in hydrograph separation of streamflow at the outlet of a forest sub-catchment was verified by through comparison with the hydrograph separation results based on δ18O data. The Fmax(C1)/Fmax(C2) ratio was then applied to estimate the contributions of rainwater and pre-event water sources under different land use types to the streamflow in an agro-forest sub-catchment and the entire catchment. The hydrograph separation results using the Fmax(C1)/Fmax(C2) ratio can be used to support the optimization of water resource management and the quantification of pollutant loadings from major water sources to streams at the catchment scale.

Experimental and Numerical Study on Shear Performance of Pitched Screws in Wood-Concrete Composite Beam with Wooden Partitions.

Wooden partitions are extensively used as formwork for pouring concrete in wood-concrete composite beams, especially in the restoring of wood structures. However, limited research has been conducted on the shear properties of pitched screw connectors in wood-concrete composite beams with wooden partitions. Therefore, this study investigated the shear performance of pitched screws in wood-concrete composite beams with wooden partitions through push-out tests and finite element analysis. The test results revealed that the failure mode of pitched screws was characterized by the pulling failure of the screws under tensile-shear action. The finite element analysis accurately predicted the failure mode, stress distribution, and load-slip behavior of pitched screws. Furthermore, the effects of the screw embedding angle, wooden partition thickness, concrete strength, and the length-diameter ratio of the screw were investigated through parametric analyses. It was found that when the screw diameter was 12 mm, the shearing capacity of the pitched screws with embedding angles of ±45°, ±60°, and ±75° decreased by 3.9%, 11.9%, and 26.9%, respectively, compared to the screws with an embedding angle of ±30°. The shearing capacity of pitched screws improved with the increase in the concrete strength and length-diameter ratio of the screw. However, the improvement in shearing capacity became less significant as the concrete strength and length-diameter ratio of the screw increased. Moreover, an increase in wooden partition thickness reduced the shearing capacity of pitched screws.

EEF1A2 accelerates the protein translation of chemokine in rat myocardial cells induced by ischemia-reperfusion.

How to reduce the damage caused by myocardial ischemia-reperfusion (IR) in a timely manner to save patients' lives is still a great clinical challenge. Although dexmedetomidine (DEX) has been reported to protect the myocardium, the regulatory mechanism of gene translation responding to IR injury and DEX protection is poorly understood. In this study, IR rat model with DEX and the antagonist yohimbine (YOH) pretreatment were established, and RNA sequencing was carried out to seek the important regulators in differential expressed genes. A series of cytokines and chemokine as well as eukaryotic translation elongation factor 1 alpha 2 (EEF1A2) were induced by IR compared to control and compromised by DEX pretreatment compared to IR, then reversed by YOH. Immunoprecipitation was conducted to identify that peroxiredoxin 1 (PRDX1) interacted with EEF1A2 and contributed to the recruitment of EEF1A2 on mRNA molecules of cytokines and chemokine. Knockdown of PRDX1 could weaken the enhancive effect of EEF1A2 for gene translation of IL6, CXCL2 and CXCL11 under the IR condition, and indeed reduce cell apoptosis of cardiomyocytes. We also determined that the RNA motif "USCAGDCU" at 5' UTR could be particularly recognized by PRDX1. Destruction of this motif at the 5' UTR of IL6, CXCL2 and CXCL11 by CRISPR-CAS9 could result in the loss occupancies of EEF1A2 and PRDX1 on the mRNA of these three genes. Our observations showed the importance of PRDX1 in the reasonable control of cytokine and chemokine expression to prevent excessive inflammatory response to cell damage.

Metal Atoms Participate in the Self-Assembly and On-Surface Reaction Behaviors of 1,4-DBN on Ag(111) Surface.

Herein, using 1,4-dibromonaphthalene (1,4-DBN) as the precursor molecule and Ag(111) surface as the substrate, we have characterized the various coordination and covalent structures formed by 1,4-DBN by low-temperature scanning tunnelling microscopy. We observed that there are three ordered structures (phase I, II, III) and one metal-organic short-chain structure (phase IV) at high coverage, meanwhile a new type of chiral structure (phase V) is observed coexisting with phase II, III, IV at low coverage. Surprisingly, all these structures have surface Ag adatoms incorporated. In addition, the phase III should be formed by a dissymmetric dehalogenation reaction of 1,4-DBN. Furthermore, we showed that the Ullmann coupling and cyclodehydrogenation of 1,4-DBN to form the armchair-shaped graphene nanoribbons will occur after thermal annealing. Combining the experiment data and density functional theory simulations, our results show that the surface Ag adatoms play a critical role in both the self-assembly and the on-surface reaction.

Effect of genetic polymorphism of UCP2-866 G/A on repaglinide response in Chinese patients with type 2 diabetes.

The aim of the present study was to evaluate the impact of the UCP2-866 G/A polymorphism on the efficacy of repaglinide in treating patients with diabetes mellitus type 2 (T2DM). 370 patients with T2DM and 166 healthy volunteers were enrolled to identify UCP2-866 G/A genotypes. 16 patients with GG genotype, 14 with GA genotype and 11 with AA genotype of UCP2-866 G/A underwent an 8-week repaglinide treatment regimen. There were no differences in allele frequency of UCP2-866 G/A between T2DM patients and control subjects. The patient with AA genotype of UCP2-866 G/A had higher levels of fasting plasma glucose (FPG), 30-min and 2-h postload plasma glucose, glycated haemoglobin (HbA1c), and lower concentrations of 30-min and 2-h postload plasma insulin, homeostasis model assessment of beta cell function (HOMA-beta), deltaI30/deltaG30 compared with GG genotype. After repaglinide treatment for 8 consecutive weeks, we found that A allele carriers of UCP2 in the T2DM patients had smaller decrease in FPG (P < 0.05) and HbA1c (P < 0.05), and smaller increase in 30-min postload plasma insulin (P < 0.01) compared with GG genotypes. We demonstrated that UCP2-866 G/A polymorphism is associated with the therapeutic efficacy of repaglinide in Chinese T2DM patients.

Keyhole supraorbital eyebrow approach for fully endoscopic resection of tuberculum sellae meningioma.

Background: The fully endoscopic supraorbital trans-eyebrow keyhole approach is a technique utilized for the transcranial resection of tuberculum sellae meningioma (TSM). Surgery is the first choice for TSM treatment. This study aimed to summarize and analyze the safety, feasibility, limitations, and technical requirements of the fully endoscopic supraorbital trans-eyebrow keyhole approach for TSM resection. Methods: Data of 19 TSM fully endoscopic supraorbital trans-eyebrow keyhole approach resections cases (six and 13 on the left and right eyebrows, respectively) were retrospectively analyzed at the Neurosurgery Department of the First Affiliated Hospital of Bengbu Medical College (Bengbu, China) from August 2015 to March 2022. Results: All 19 patients were diagnosed with meningioma (World Health Organization grade I), and according to the scope of tumor resection (EOR), 18 patients (94.7%) had gross total resection (GTR), and one patient (5.3%) had near-total resection (NTR). Preoperative chief complaints were symptomatic visual dysfunction (n = 12), headache and dizziness (n = 6), and accidental discovery (n = 1). Postoperative visual function improved in 83.3% of cases (10/12), and headache and dizziness were relieved in 83.3% of cases (5/6 patients). Postoperative intracranial infection occurred in one case and was cured by external drainage of the lumbar cistern and anti-infective treatment. Two cases of frontal lobe injury were discharged after conservative treatment. There was no postoperative olfactory dysfunction, eyelid ptosis, cerebrospinal fluid leakage, or death. There were no reports of disease recurrence or death during the 3-month follow-up at an outpatient clinic or by telephone. Conclusion: Fully endoscopic TSM resection through the keyhole approach is safe and feasible. It can be used to explore angles that cannot be seen under a microscope and show the true value of endoscopy technology. The endoscopic equipment and technical skills of the surgeon and surgical team are important in this technique.