Role of Cyclooxygenase-2 in Head and Neck Tumorigenesis

The cyclooxygenase-2 (COX-2) is a potent enzyme that converts arachidonic acid to prostaglandins (PG), including PGE2, a key mediator of inflammation and angiogenesis. Importantly, COX-2 is activated in response to inflammatory stimuli, where it is also believed to promote the development and progression of head and neck cancers (HNC). COX-2 can mediate its protumorigenic effect through various mechanisms, such as inducing cell proliferation, inhibition of apoptosis, and suppressing the host’s immune response. Furthermore, COX-2 can induce the production of vascular endothelial growth factors, hence, promoting angiogenesis. Indeed, the ability of COX-2 inhibitors to selectively restrict the proliferation of tumor cells and mediating apoptosis provides promising therapeutic targets for cancer patients. Thus, in this comprehensive review, we summarized the reported differential expression patterns of COX-2 in different stages of head and neck carcinogenesis—from potentially premalignant lesions to invasive carcinomas. Furthermore, we examined the available meta-analysis evidence for COX-2 role in the carcinogenesis of HNC. Finally, further understanding of the biological processes of COX-2 and its role in orchestrating cell proliferation, apoptosis, and angiogenesis may give therapeutically beneficial insight to develop the management plan of HNC patients and improve their clinical outcomes.     

Microwave dielectric properties of SrLa[Ga1−x(Mg0.5Ti0.5)x]O4 and SrLa[Ga1−x(Zn0.5Ti0.5)x]O4 (x = 0.2-0.8) ceramics

SrLa[Ga_1−x(R_0.5Ti_0.5)_x]O₄ (R = Mg, Zn) ceramics were prepared by a standard solid state sintering method. The single-phase ceramics with K₂NiF₄-type layered perovskite structure and I4/mmm space group were obtained, indicating that SrLa(R_0.5Ti_0.5) and SrLaGaO₄ can form the unlimited solid solutions. With increasing x for R = Mg and Zn, ε_r increases monotonously, the Qf value first increases and then decreases, while τ_f increases from a negative to a positive value. The optimized microwave dielectric properties were obtained as following: ε_r = 23.3, Qf = 89 400 GHz, τ_f = −0.8 ppm/°C for SrLa[Ga_0.6(Mg_0.5Ti_0.5)_0.4]O₄ and ε_r = 23.3, Qf = 76 200 GHz, τ_f = 0.2 ppm/°C for SrLa[Ga_0.7(Zn_0.5Ti_0.5)_0.3]O₄, indicating that the present solid solution ceramics are the promising candidates as microwave resonator materials for the telecommunication applications.     

CO2对油田地下水环境中Q235钢和X70钢腐蚀行为的影响

为了探明辽河油田地下水环境中CO₂对Q235钢和X70管线钢的腐蚀规律,采用动电位极化技术及交流阻抗技术研究了不同CO₂浓度对该环境下两种钢腐蚀行为的影响,并利用光学显微镜对试样腐蚀界面进行表征。结果表明:随着CO₂浓度的增加,Q235和X70钢的交流阻抗图谱的半径均减小,腐蚀电流密度增大,腐蚀坑数量、深度和面积都增加,腐蚀敏感性增大。在低浓度CO₂环境下(CO₂含量为10%时),Q235钢的腐蚀敏感性比X70钢更高;而在高浓度CO₂环境下(CO₂含量为20%、40%、60%时),Q235钢的腐蚀速率反而较小,耐腐蚀性更好。     

B对FeCoCrNiSiBx高熵合金激光熔覆层组织和硬度的影响

采用激光熔覆制备了FeCoCrNiSiB_x高熵合金熔覆层,利用光学显微镜、扫描电镜、X射线衍射仪和显微硬度计研究微量硼元素(摩尔比x=0、0.02、0.04、0.06、0.08)对FeCoCrNiSiB_x高熵合金熔覆层组织和硬度的影响。结果表明:无B高熵合金涂层组织主要为胞状晶。B的添加会促进枝晶的生成,逐渐形成鱼骨状树枝晶,但过量的B会破坏枝晶完整性,形成蠕虫状晶。此外,高熵合金熔覆层组织为FCC和BCC双相结构,B元素的添加会形成大量0.1~2.6 μm的Cr₂B第二相,有助于提高熔覆层硬度,其中x=0.06时激光熔覆层的硬度最高,约为537 HV0.2。     

Effect of cutting process on the stress corrosion susceptibility of AISI 304L stainless steel

During manufacturing of a component, cutting, turning, grinding, and milling operations are inevitable and these operations induce surface residual stresses. In this study, it is shown that, depending on the process employed for cutting, residual stresses generated at the cut surfaces can vary widely and they can, in turn, make the cut surfaces of austenitic stainless steel (SS) prone to stress corrosion cracking (SCC). An austenitic SS 304L plate was cut using three different procesess: bandsaw cutting, cutting using the cut-off wheel, and shearing. Surface residual stress measurement using the X-ray diffraction (XRD) technique is carried out close to the cutting edges and on the cross-section. SCC susceptibility studies were carried out as per ASTM G36 in 45% boiling magnesium chloride solution. Optical microscopic examination showed the presence of cracks, and confocal microscopy was used to measure the depth of cracks. The study confirmed that high tensile residual stresses present in the cut surfaces produced by cut-off wheel and shear cutting make the surfaces susceptible to SCC while the surfaces produced by bandsaw cutting are resistant to SCC. Hence, it is shown that there is a definite risk of SCC for product forms of austenitic SS with cut surfaces produced using cutting processes that generate high tensile residual stresses stored for a long period of time in a susceptible environment.     

CVD涂层α-Al2O3织构制备技术研究

采用化学气相沉积法在硬质合金基体上沉积具有不同织构择优的α-Al2O3涂层,通过扫描电子显微镜(SEM)、X射线衍射(XRD)分别对其微观组织和机械性能进行分析。研究结果表明,通过改善过渡层的氧化气氛,氧化铝的过渡层结构为针状物,成功制备不同织构的氧化铝涂层,涂层结合力良好。     

3D and simplified pseudo-2D modeling of single cell of a high temperature solid oxide fuel cell to be used for online control strategies

In the current study, a single cell of a planar SOFC is firstly modeled in 3D using commercial SOFC module of ANSYS Fluent and the results are validated against the experimental investigations in the literature. Many researchers have used ANSYS Fluent for simulating solid oxide fuel cells. However, there is a huge gap in the literature on explaining the detailed procedure that should be followed in order to use this software effectively. A thorough step-by-step approach is presented to provide a deep insight into the software. Thereafter, a simplified quasi-2D method with infinitely shorter computational time is developed and the results are compared with the 3D model. It is found that the reduced model is capable of being utilized as an alternate method for both online diagnosis and designing active control strategies.     

Electrical oscillation generation with current-induced resistivity switching in VO2 micro-channel devices

We report large amplitude modulation waveforms as large as ~ 10 V using vanadium dioxide micro-channel devices operating under current-controlled conditions. The self-sustained electrical oscillations were generated by controlling the applied current in the negative differential resistance region of the investigated devices. An appropriate value of internal capacitance was achieved as parasitic capacitance in the device structure to stabilize the electrical oscillations. This eliminates the need of an external pulsed source or any external passive component connected to the micro-channel devices. Amplitude and frequency of the oscillation were tuned by illuminating the device micro-channel with an external laser. An equivalent circuit model was developed to simulate the waveforms. A good agreement between experiment and simulation was verified.     

Electro-magneto temperature-dependent vibration analysis of functionally graded-carbon nanotube-reinforced piezoelectric Mindlin cylindrical shells resting on a temperature-dependent,orthotropic elastic medium

Vibration smart control analysis of a temperature-dependent functionally graded-carbon nanotube-reinforced piezoelectric cylindrical shell embedded in an orthotropic elastic medium is investigated. The mixture law is used for obtaining the material properties of the structure. The structure is subjected to a 2D magnetic field. Considering the first-order shear deformation theory, the motion equations are obtained. Based on an analytical method and differential quadrature method, the frequency is calculated. The effects of applied voltage, magnetic field, volume percent, and distribution type of carbon nanotubes, temperature, orthotropic elastic medium, and length to radius ratio of the shell are shown on system frequency.     

A Polyallylamine Anchored Amine‐Rich Laser‐Ablated Graphene Platform for Facile and Highly Selective Electrochemical IgG Biomarker Detection

Current immunosensors have an insufficient number of binding sites for the recognition of biomolecules, which leads to false positive or negative results. In this research, a facile, cost‐effective, disposable, and highly selective electrochemical immunosensing platform is developed based on cationic polyelectrolyte polyallylamine (PAAMI) anchored laser‐ablated graphene (LAG). Here, for the first time, PAAMI is introduced to stabilize LAG flakes, while retaining the intrinsic thermal and electronic properties of the substrate by noncovalent π–π interaction and electrostatic physical absorption. The sensing platform offers a suitable number of anchoring sites for the immobilized antibodies by providing ? NH₂ functional groups. The proper grafting of PAAMI is confirmed through X‐ray photoelectron spectroscopy and Raman spectroscopy. The immunosensing platform is applied to detect immunoglobulin (IgG) biomarkers as a proof of concept. Under optimized conditions, the sensing platform exhibits a linear range of 0.012–15 and 15–352 ng mL^?1 with a limit of detection of 6 pg mL^?1 for IgG detection with high selectivity. Based on the analysis, the developed immunosensing platform can be used for point‐of‐care detection of IgG in clinical diagnostic centers. Furthermore, the developed strategy is well suited for the detection of other cancer biomarkers after immobilizing the relevant antibodies.