Quantitative microRNA (miRNA) detection is crucial for early breast cancer diagnosis and prognosis. However, quick and stable fluorescence sensing for miRNA identification is still challenging. This work developed a novel label-free detection method based on AuNPs etching for quantitatively detecting miRNA-155. A layer of AuNPs was grown on the surface of mesoporous silica nanoparticles (MSN) loaded with Rhodamine 6G (R6G) using seed-mediated growth, followed by probe attachment. In the presence of miRNA-155, the MSN@R6G@AuNP surface loses the protection of the attached probe, rendering AuNPs susceptible to etching by hydrochloric acid. This results in a significant fluorescent signal being released in the free space. The encapsulation with AuNPs effectively reduces signal leakage, while the rapid etching process shortens detection time. This strategy enables sensitive and fast detection with a detection range of 100 fM to 100 nM, a detection limit of 2.18 fM, and a detection time of 30 min. The recovery rate in normal human serum ranges from 99.02 % to 106.34 %. This work presents a simple biosensing strategy with significant potential for application in tumor diagnosis.

Cold atmospheric pressure plasma (CAP) treatment has been shown to kill bacteria and remove bacterial biofilms from surfaces. Here we report the etch capacity of a linear discharge CAP device on Pseudomonas fluorescens biofilms. A 21 kHz, 1.4 kV RMS AC voltage applied to the CAP electrodes generated a hydrated Ar plasma between the plates, with the gas flow directing the plasma species toward the biological sample, causing both bacterial killing and etching of the biofilm. Typical discharge currents for a 2.4 cm long, 0.6 mm wide linear discharge device were 1-4.4 mA. Hydrated Ar flow gas was critical for removal of biofilm from a stainless steel substrate, while both hydrated and dry Ar + O2, Ar + air, O2 only, and air only flow gas mixtures did not cause etching at equivalent or greater discharge current intensities. A biofilm etch rate of > 2 μm/min was achieved, provided the plasma discharge was within 1-2 mm of the substrate surface and used a hydrated Ar gas flow of at least 5 LPM.

BACKGROUND: In dental practice, different situations require etching the enamel layer. Acid etching, the present golden standard, may be replaced by other methods, such as laser etching. The main focus of our scoping review is to assess the existent literature regarding the effectiveness of different types of lasers, to identify the main aspects studied so far, and to understand where new search strategies are needed.
METHODS: The search was conducted in several databases focusing on the laser etching of human definitive enamel. We included English language articles published between January 2000 and December 2021.
RESULTS: The 34 articles reviewed showed that hard lasers, Er:YAG, Er,Cr:YAG, may represent an alternative etching method on enamel surfaces. They create a fractured, irregular surface and open dentin tubules, highly suitable for adhesion but with a lower risk of cavity formation. Nd:YAG, CO2, and Diode lasers do not help in creating sufficient shear bond strength. There is, however, evidence suggesting that microcracks in the enamel layer may appear after thermomechanical ablation using laser energy.
CONCLUSIONS: While the use of acid etching is still successfully used for enamel conditioning, some researchers have emphasized the role played by saliva in the enamel-remineralization process a few days after the procedure. In this context, laser energy can be used, especially for bonding ceramic brackets in the case of orthodontic treatments. However, as thermomechanical ablation can generate microcracks, further research is required in order to establish clear findings concerning the use of laser energy on enamel etching.

The properties of alfalfa-derived biochars etched with phosphoric (PBC) or hydrochloric acid (ClBC) compared with raw materials (BC) were examine in this paper. SEM, FT-IR, XRD, BET and elemental analysis were performed to characterize the micromorphology and chemical structure comprehensibly. The results showed that the porous structure was enhanced, and surface area was increased via etching with inorganic acids. Batch adsorption experiments were performed for sulfamethoxazole (SMX) to biochars. The experimental data showed that modified biochars exhibited higher adsorption capacity for SMX, i.e., the adsorption quantity of ClBC and PBC had risen by 38% and 46%. The impact on pH values suggested that the physisorption, including pore-filling and electrostatic interaction, might be applied to original biochar. In addition, chemisorption also played a role, including hydrogen bonding, π-π electron donor acceptor interaction (π-π EDA), and so on. Furthermore, both pH and coexisting ions also had a certain effect on sorption. Enhancement of the electrostatic attraction between biochar and SMX might also account for the enhanced capacity of SMX at pH < 7, and coexisting ions could decrease the amount of SMX adsorbed onto biochars, mainly because of competition for adsorption sites.

Heavily doped polysilicon layers have been widely used in the fabrication of microelectromechanical systems (MEMS). However, the investigation of high selectivity, anisotropy, and excellent uniformity of heavily doped polysilicon etching is limited. In this work, reactive ion etching of undoped and heavily doped polysilicon-based hydrogen bromide (HBr) plasmas have been compared. The mechanism of etching of heavily doped polysilicon is studied in detail. The final results demonstrate that the anisotropy profile of heavily doped polysilicon can be obtained based on a HBr plasma process. An excellent uniformity of resistance of the thermocouples reached ± 2.11%. This technology provides an effective away for thermopile and other MEMS devices fabrication.

Herein, we report a novel Fe foil-guided, in situ etching strategy for the preparation of highly uniform Ag@AgX (X = Cl, Br) nanowires (NWs) and applied the photoelectric-responsive materials for sensitive photoelectrochemical (PEC) detection of leukemia DNA. The Ag@AgX NW formation process was discussed from the redox potential and Ksp value. The fabricated PEC platform for sensing leukemia DNA showed good assay performance with a wide linear range (0.1 pM to 50 nM) and low detection limit of 0.033 pM. We envision that our Fe foil-guided synthetic method could be applied to synthesize more photoactive materials for sensitive PEC detections.

Using an atomic force microscope (AFM), the wear of monocrystalline silicon (covered by a native oxide layer) at high humidity was investigated. The experimental results indicated that tribochemistry played an important role in the wear of the silicon at different relative humidity levels (RH = 60%, 90%). Since the tribochemical reactions were facilitated at 60% RH, the wear of silicon was serious and the friction force was around 1.58 μN under the given conditions. However, the tribochemical reactions were restrained when the wear pair was conducted at high humidity. As a result, the wear of silicon was very slight and the friction force decreased to 0.85 μN at 90% RH. The slight wear of silicon at high humidity was characterized by etching tests. It was demonstrated that the silicon sample surface was partly damaged and the native oxide layer on silicon sample surface had not been totally removed during the wear process. These results may help us optimize the tribological design of dynamic microelectromechanical systems working in humid conditions.

Suspended crystalline Ge semiconductor structures are created on a Si(001) substrate by a combination of epitaxial growth and simple patterning from the front surface using anisotropic underetching. Geometric definition of the surface Ge layer gives access to a range of crystalline planes that have different etch resistance. The structures are aligned to avoid etch-resistive planes in making the suspended regions and to take advantage of these planes to retain the underlying Si to support the structures. The technique is demonstrated by forming suspended microwires, spiderwebs and van der Pauw cross structures. We finally report on the low-temperature electrical isolation of the undoped Ge layers. This novel isolation method increases the Ge resistivity to 280 Ω cm at 10 K, over two orders of magnitude above that of a bulk Ge on Si(001) layer, by removing material containing the underlying misfit dislocation network that otherwise provides the main source of electrical conduction.