Control of Porous Layer Thickness in Thermophoretic Deposition of Nanoparticles

The film thickness plays an important role in the performance of materials applicable to different technologies including chemical sensors, catalysis and/or energy materials. The relationship between the surface and volume of the functional layers is key to high performance evaluations. Here we demonstrate the thermophoretic deposition of different thicknesses of the functional layers designed using flame combustion of tin 2-ethylhexanoate dissolved in xylene, and measurement of thickness by scanning electron microscopy and focused ion beam. The parameters such as spray fluid concentration (differing Sn²⁺ content), substrate-nozzle distance and time of the spray were considered to investigate the layer growth. The results showed ≈ 23, 124 and 161 μm thickness of the SnO₂ layer after flame spray of 0.1, 0.5 M and 1.0 M tin 2-EHA-Xylene solutions for 1200 s. While Sn²⁺ concentration was 0.5 M for all the flame sprays, the substrates placed at 250, 220 and 200 mm from the flame nozzle had layer thicknesses of 113, 116 and 132 µm, respectively. Spray time dependent thickness growth showed a linear increase from 8.5 to 152.1 µm when the substrates were flame sprayed for 30 s to 1200 s using 0.5 M tin 2-EHA-Xylene solutions. Changing the dispersion oxygen flow (3–7 L/min) had almost no effect on layer thickness. Layers fabricated were compared to a model found in literature, which seems to describe the thickness well in the domain of varied parameters. It turned out that primary particle size deposited on the substrate can be tuned without altering the layer thickness and with little effect on porosity. Applications depending on porosity, such as catalysis or gas sensing, can benefit from tuning the layer thickness and primary particle size.     

Imaging update on soft tissue sarcoma

Soft tissue sarcomas (STS) are rare tumours presenting as soft tissue lumps. Ultrasound is often the primary modality for the initial assessment, with MRI the mainstay for lesion characterisation. PET/CT along with other emerging MRI sequences are used in certain situations as an adjunct and problem solving tool in STS staging and assessment of disease recurrence. Recent advances include the promise of whole body MRI, hybrid PET/MRI, diffusion weighted imaging, dynamic contrast enhanced MRI and advances in artificial intelligence. This article discusses current concepts in extremity STS imaging and highlights recent advances.     

Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

In this study, silicon nitride (SiN_x) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiN_x/PI substrates at room temperature (RT), 100 and 200 °C by radio frequency (RF) magnetron sputtering. The thicknesses of the GZO and SiN_x thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiN_x thin films were a working pressure of 800 × 10⁻³ Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH₄ = 20 sccm and NH₃ = 210 sccm, respectively. For the GZO/PI and GZO-SiN_x/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiN_x/PI substrates with thickness of ~000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si) thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiN_x/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiN_x/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiN_x/PI.     

高原地区首例新型冠状病毒肺炎CT诊断分析并文献复习

目的回顾性分析高原地区首例新型冠状病毒肺炎的CT影像特征及临床表现,以提高对该病的认识。方法回顾性分析高原地区1例确诊新型冠状病毒患者的CT影像及临床资料并进行文献复习。结果患者患病过程中早期、进展期及转归期的CT表现较为典型,与内地文献报道无明显差异,但诊断时应与高原性病种相互鉴别。结论新型冠状病毒肺炎的诊断除结合临床特征、实验室检查、流行病学史及核酸检测外,CT扫描在治疗后的复查及早期的诊断可以提供必要的补充资料,熟悉该病CT诊断的分期表现有助于诊断。     

Theoretical Methods of Domain Structures in Ultrathin Ferroelectric Films: A Review

This review covers methods and recent developments of the theoretical study of domain structures in ultrathin ferroelectric films. The review begins with an introduction to some basic concepts and theories (e.g., polarization and its modern theory, ferroelectric phase transition, domain formation, and finite size effects, etc.) that are relevant to the study of domain structures in ultrathin ferroelectric films. Basic techniques and recent progress of a variety of important approaches for domain structure simulation, including first-principles calculation, molecular dynamics, Monte Carlo simulation, effective Hamiltonian approach and phase field modeling, as well as multiscale simulation are then elaborated. For each approach, its important features and relative merits over other approaches for modeling domain structures in ultrathin ferroelectric films are discussed. Finally, we review recent theoretical studies on some important issues of domain structures in ultrathin ferroelectric films, with an emphasis on the effects of interfacial electrostatics, boundary conditions and external loads.     

Self‐perceived mouthfeel and physico‐chemical surface effects after chewing gums containing sorbitol and Magnolia bark extract

The European Food Safety Authority recognizes the contribution of sugar‐free chewing gum to oral health through increased salivation, clearance of food debris, and neutralization of biofilm pH. Magnolia bark extract is a gum additive shown to reduce the prevalence of bad‐breath bacteria but its effects on self‐perceived mouthfeel are unknown. This paper aims to relate the effects of sorbitol‐containing chewing gum, with and without Magnolia bark extract, on tooth‐surface hydrophobicity and salivary‐film composition with self‐perceived mouthfeel. In a crossover clinical trial, volunteers chewed sorbitol‐containing gum, with or without Magnolia bark extract added, three times daily during a 4‐wk time period. A subset of volunteers also chewed Parafilm as a mastication control. Oral moistness and tooth smoothness were assessed using questionnaires, and intra‐oral water‐contact angles were measured before, immediately after, and 60 min after, chewing. Simultaneously, saliva samples were collected, placed on glass slides, and the compositions of the adsorbed film were measured using X‐ray photoelectron spectroscopy. Chewing of gum, regardless of whether or not it contained Magnolia bark extract, improved self‐perceived mouthfeel up to 60 min, concurrent with a more hydrophilic tooth surface and an increased amount of O_1s electrons bound at 532.6 eV in salivary films. Chewing of Parafilm affected neither tooth‐surface hydrophobicity nor salivary‐film composition. Accordingly, adsorption of sorbitol, rather than the presence of Magnolia bark extract or increased salivation, is responsible for improved self‐perceived mouthfeel.     

Evaluation of clinical and financial outcomes of a new no‐sting barrier film and barrier cream in a large UK primary care organisation

The study involves 95 subjects within a UK Primary Care Organisation and was undertaken in two arms. The objective was to determine the clinical outcomes and clinical acceptability of a newly available range of no‐sting barrier film and no‐sting barrier cream products offering significant financial benefits. The importance of undertaking this study is underpinned by evidence in the literature relating to the use of no‐sting barrier preparations within clinical practice. The first part of the study (arm 1) involved extensive evaluation of either the film or cream barrier in 36 patients and was compared to existing standardised barrier protection care within the organisation. The results indicated that the new product range met all the criteria for formulary inclusion and following this the barrier range was further evaluated in arm 2, 33 patients with barrier cream and 26 patients with barrier film. The entire study was conducted over a 3‐month period with patient treatment lasting a minimum of 2 days to a maximum 4‐week period adhering to the agreed evaluation protocol as approved by clinical governance. In arm 1 (n = 36), the clinical expectation of the product was met in 32 cases relating to ease of use, conformability, no‐sting, quick drying, ease of absorption, compatibility with devices, frequency of application, prevention and management including visual skin improvement resulting in a recommendation for formulary listing in 31 of 36 cases. In arm 2 (n = 59), barrier film and barrier cream performance was consistently rated same as, better than or much better than the existing barrier used. A formulary listing recommendation was made in 51 of 59 cases.     

Development and evaluation of novel biodegradable chitosan based metformin intrapocket dental film for the management of periodontitis and alveolar bone loss in a rat model

ObjectiveThe aim of this study was to develop a chitosan-metformin based intrapocket dental film (CMIDF) for applications in the treatment of periodontitis and alveolar bone loss in an rat model of periodontitis.DesignCMIDF inserts were fabricated by the solvent casting technique. The fabricated inserts were evaluated for physical characteristics such as folding endurance, surface pH, mucoadhesive strength, metformin content uniformity, and release. X-ray diffraction analysis indicates no crystallinity of metformin in presence of chitosan which confirmed successful entrapment of metformin into the CMIDF. Fourier-transform infrared spectroscopy revealed stability of CMIDF and compatibility between metformin and chitosan. Periodontitis was induced by a combination of Porphyromonas gingivalis- lipopolysaccharide injections in combinations with ligatures around the mandibular first molar. We divided rats into 5 groups (8 rats/group): healthy, untreated periodontitis; periodontitis plus CMIDF-A (1.99 ± 0.09 mg metformin; total mass-4.01 ± 0.05 mg), periodontitis plus CMIDF-B (2.07 ± 0.06 mg metformin; total mass-7.56 ± 0.09 mg), and periodontitis plus chitosan film (7.61 ± 0.08 mg). After four weeks, mandibles were extracted to evaluate alveolar bone loss by micro-computerized tomography and histological techniques.ResultsAlveolar bone was intact in the healthy group. Local administration of CMIDF resulted in significant improvements in the alveolar bone properties when compared to the untreated periodontitis group. The study reported here demonstrates that novel CMIDF showed good antibacterial activity and effectively reduced alveolar bone destruction in a rat model of experimental periodontitis.ConclusionsNovel CMIDF showed good antibacterial activity and improved alveolar bone properties in a rat model.     

Electrochemical and surface analyses of nanostructured Ti–24Nb–4Zr–8Sn alloys in simulated body solution

The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti–24Nb–4Zr–8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37 °C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott–Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring.