Methane gas sensor based on direct absorption spectroscopy and the laser self-heating effect.

In this paper, a methane detection sensor based on direct absorption spectroscopy and the self-heating effect of lasers is proposed, which abandons the traditional method of relying on a thermoelectric cooler (TEC) to ensure stable gas concentration detection. The sensor can achieve stable concentration measurement in the temperature range of -10∘ to 40°C without the need for a TEC, which greatly simplifies the structure of the sensor and reduces the cost. The results of gas concentration calibration experiments show that the sensor has a good linear correlation (R 2=0.9993). Long-term continuous detection experiments show that the sensor maintains a relative detection error between -2.667% and 4.3% over the full test temperature range. In addition, signal-to-noise ratio analysis experiments further determine that the minimum detection limit of the sensor for methane gas is 27.33p p m⋅m (1σ). Given its advantages of simple structure, low cost, high accuracy, and stability, this methane detection sensor is well suited for natural gas leakage monitoring in home environments and can also be widely used in industrial safety detection and environmental monitoring applications. This technology provides a cost-effective solution for domestic and industrial methane detection.

catena-Poly[3,3'-diethyl-1,1'-(propane-1,3-di-yl)di(1H-imidazol-3-ium) [silver(I)-di-µ-iodido-silver(I)-di-µ-iodido]].

The title compound, {(C(13)H(22)N(4))[Ag(2)I(4)]}(n), was prepared by reaction of 1,3-bis-(N-ethyl-imidazolium-1-yl)propane iodide with silver (I) oxide. In the 3,3'-diethyl-1,1'-(propane-1,3-di-yl)di(1H-imidazol-3-ium) cation, the dihedral angle between the imidazole rings is 49.3 (1)°. In the [Ag(2)I(4)](2-) anion, each Ag(I) atom is bonded to three iodide anions, the two Ag(I) atoms and two of the iodides forming Ag(2)I(2) square-planar (r.m.s. deviation = 0.01 Å) units·The remaining two iodides, which are placed on opposite sides of the square, together with their centrosymmetric counterparts, link the square-planar Ag(2)I(2) units into {[Ag(2)I(4)](2-)}(n) polymeric chains via Ag-I bonds.

The Efficacy and Safety of Transurethral 2 µm Laser Bladder Lesion Mucosal En Bloc Resection in the Treatment of Cystitis Glandularis.

Objective: To study the safety and feasibility of transurethral bladder lesion mucosal en bloc resection with 2 µm laser for cystitis glandularis. Methods: From July 2018 to July 2019, 58 patients with cystitis glandularis received surgical treatment were selected. All patients in this study were randomly divided into experimental group (transurethral 2 µm laser bladder lesion mucosal en bloc resection) and control group (traditional transurethral resection of bladder lesion mucosal). By analyzing the perioperative and follow-up clinical data of these two operation procedures, we discuss the efficacy and safety of transurethral 2 µm laser bladder lesion mucosal en bloc resection in the treatment of cystitis glandularis. Results: Patients of two groups received operation successfully without serious complications such as bladder perforation. Compared with the experimental group, the laser treated group hadless bleeding in operation, shorter post-operative catheter indwelling time. These differences were statistically significant. No significant difference existed between two groups in terms of operative time, Bladder flushing time, irritation symptoms of bladder. Conclusion: Transurethral 2 µm laser bladder lesion mucosal en bloc resection is safe and effective for the treatment of cystitis glandularis, and it is worthy of further clinical application.