Hydration of the methanesulfonate–ammonia/amine complex and its atmospheric implications

Methanesulfonate (MSA⁻), found in substantial concentrations in the atmosphere, is expected to enhance aerosol nucleation and the growth of nanoparticles, but the details of methanesulfonate clusters are poorly understood. In this study, MSA⁻ was chosen along with ammonia (NH₃) or three common amines and water (H₂O) to discuss the roles of ternary homogeneous nucleation and ion-induced nucleation in aerosol formation. We studied the structural characteristics and thermodynamics of the clusters using density functional theory at the PW91PW91/6-311++G(3df,3pd) level. The analysis of noncovalent interactions predicts that the amines can form more stable clusters with MSA⁻ than NH₃, in agreement with the results from structures and thermodynamics; however, the enhancement in stability for amines is not large enough to overcome the difference in the concentrations of NH₃ and amines under typical atmospheric conditions. In addition, the favorable free energies of formation for the (MSA⁻)(NH₃/amines)(H₂O)_n (n = 0–3) clusters at 298.15 K show that MSA⁻ could contribute to the aerosol nucleation process with binding NH₃/amines and H₂O up to n = 3. There are strong temperature and humidity dependences for the formation of complexes; higher humidity and temperature promote the formation of larger hydrates. Finally, for the (MSA⁻)(NH₃/amines)(H₂O)_n clusters, the evaporation rates were determined to further investigate the atmospheric implications.

Methanesulfonate (MSA⁻), found in substantial concentrations in the atmosphere, is expected to enhance aerosol nucleation and the growth of nanoparticles, but the details of methanesulfonate clusters are poorly understood.     

Performance and mechanism of free nitrous acid on the solubilization of waste activated sludge

Free nitrous acid (FNA) is a promising chemical reagent for excess sludge reduction. The distinctive properties of FNA treatment on waste activated sludge (WAS) disposal have previously been demonstrated, however, the cellular response, permeabilization, and disruption caused by low-concentration FNA and the direct cell solubilization of WAS using concentrated FNA should be better understood. In this study, the parameters that influence the sludge solubilization efficiency were optimized over a wide range of FNA concentrations. The sludge solubilization efficiency was found to be superior when the sludge was exposed to FNA (when the dosage of NaNO₂ was 0.12 g g⁻¹ TSS and the pH was 3.0, FNA = 20.94 mg L⁻¹) for 10 h at 25 °C, and the TSS removal and COD dissolution efficiencies were found to be prominent at 38% and 7%, respectively. In the FNA treatment of WAS, some FNA-tolerable cells increased the K⁺, Ca²⁺, and H⁺ effluxes under low concentrations of FNA, and finally achieved ion homeostasis based on the results using a scanning ion-selective electrode measurement technique. This could cause the cells in WAS to maintain cytoactivity and integrity under a low-concentration FNA treatment. Furthermore, flow cytometry was used to assess the permeabilization and disruption of sludge cells toward a concentration gradient of FNA. Flow cytometry results indicated that cells in sludge flocs were disrupted within 30 minutes when the FNA concentration was above 8 mg L⁻¹.

The mechanism of sludge solubilization induced by free nitrous acid over a large concentration range was investigated using SIET and FCM.     

Fluorescence enhancement of carbon dots by graphene for highly sensitive detection of tetracycline hydrochloride

In this study, fluorescence of self-assembled multilayers (SAMs) of carbon dots (CDs) was found to be enhanced by graphene. The number of polyelectrolyte layers can be tuned to control the distance between CDs and graphene in SAMs. The enhanced fluorescence efficiency was found to be dependent on graphene concentration, degree of graphene reduction, and the distance between CDs and graphene surface. When graphene concentration and polyelectrolyte bilayer number were set to 0.005 mg mL⁻¹ and 3 layers, respectively, fluorescence intensity of CDs could be increased up to 3.2 times. Tetracycline hydrochloride (Tc) could be detected by the established SAMs in the presence of graphene as the sensitivity was 2 orders higher than that of SAMs in the absence of graphene. Limit of detection of this sensing system was 0.9284 nM, which is 1–3 orders of magnitude lower than those of most of reported fluorescence sensors. This method could be successfully applied to detect trace Tc in milk samples.

The fluorescence of carbon dots self-assembled multilayers (CDs SAMs) can be enhanced by graphene, the sensing sensitivity for tetracycline hydrochloride of CDs SAMs with graphene is two orders higher than that of SAMs without graphene.     

Absence of developmental toxicity in a canine model after infusion of a hemoglobin-based oxygen carrier: Implications for risk assessment

Bovine-derived hemoglobin-based oxygen carriers (HBOCs) have been investigated for use in humans (HBOC-201) and approved for veterinary medicine (HBOC-301). We infused pregnant beagles with HBOC-201 to test whether HBOC-induced developmental toxicity previously observed in rats would occur in a species devoid of an inverted visceral yolk sac (invVYS). Phase 1 assessed developmental toxicity of 6 g/kg HBOC-201 on gestational day (GD) 21. Phase 2 investigated single infusions of 6 g/kg HBOC-201 on one of GDs 21, 25, 29 or 33. Phase 3 studied multiple sequential infusions on GDs 21, 23,25,27,29, 31, and 33 at 0.52 g/kg/day (3.6 g/kg total dose). Mild to moderate maternal toxicity occurred in all phases. There was an unequivocal absence of developmental toxicity in all phases. Overall, our hypothesis that HBOC, which interferes with the function of the invVYS, would not affect the offspring in dogs was supported. The implications relative to human risk are discussed.     

结直肠息肉伴高级别瘤变内镜下切除术后复发因素的分析

目的探讨结直肠息肉伴高级别瘤变内镜切除术后息肉复发的危险因素,为临床监测提供参考依据。方法收集2013年7月-2017年3月该院结直肠息肉伴高级别瘤变行内镜切除术且有术后随访资料的患者67例,统计术后复发情况,并进行回顾性分析。对患者特征和可能影响术后息肉复发的相关因素[性别、年龄、体重指数(BMI)、吸烟史、饮酒史、息肉部位、大小、形态及数目]进行单因素和多因素分析。结果结直肠息肉伴高级别瘤变内镜切除术后1、2和3年息肉复发率分别为7.5%、17.7%和23.5%。术后3年息肉累计复发率为41.8%,其中高级别瘤变累计复发率为7.5%。高龄、肥胖、直径 2.0 cm息肉和多发性息肉的患者术后复发率较高,多因素分析显示息肉数目是息肉复发的独立危险因素(OR=3.191,95%CI:1.056～9.641)。结论结直肠息肉伴高级别瘤变内镜切除术后息肉复发率较高,且随着随访时间的延长而升高。术前息肉数目是预测息肉复发的重要因素。     

鼻窦炎合并糖尿病内镜手术患者术后并发症的护理观察

目的探析鼻窦炎合并糖尿病内镜手术患者术后并发症的护理方法及护理效果。方法用数字随机表法将2018年1月—2019年7月于该院接受内镜手术的50例鼻窦炎合并糖尿病患者分为两组,对照组(n=25)实施常规护理,观察组(n=25)实施护理干预,对比护理效果。结果与对照组相比,观察组的术后并发症发生率更低;两组患者护理前的空腹血糖、餐后2 h血糖相比差异无统计学意义(P>0.05),而护理后两组的血糖值较护理前均降低,且观察组的空腹血糖、餐后2 h血糖水平更低,差异有统计学意义(P<0.05);两组患者的护理后的焦虑、抑郁情绪评分均显著小于护理前,且观察组的负面情绪评分明显小于对照组,差异有统计学意义(P<0.05)。结论鼻窦炎合并糖尿病内镜手术患者接受护理干预能够降低并发症的发生风险,同时也有利于患者血糖的控制与稳定,有积极意义,值得推广应用。     

Effect of Spraying Power on Oxidation Resistance of MoSi2-ZrB2 Coating for Nb-Si Based Alloy Prepared by Atmospheric Plasma

The MoSi₂-ZrB₂ coatings were prepared on Nb-Si based alloy by atmospheric plasma spraying with the spraying power 40, 43 and 45 kW. The effect of spraying power on the microstructure and oxidation resistance of MoSi₂-ZrB₂ coating at 1250 °C were studied. The results showed that the main constituent phases of coatings were MoSi₂ at all spraying power. The coating became more compact as the spraying power increased. The coating prepared at 45 kW was dense and uniform, which exhibited the best oxidation resistance due to the formation of a dense and uniform glass layer consisting of SiO₂ and ZrSiO₄.     

A Novel Micro-Displacement Sensor Based on Double Optical Fiber Probes Made through Photopolymer Materials

In this paper, a novel micro-displacement sensor with double optical fiber probes is proposed and designed, which can realize the highly sensitive sensing of longitudinal or lateral micro-displacements. The optical fiber probes are made through photopolymer formulation, and the effects of reaction time and optical power on the growth length of the probe are illustrated. The relationship between light intensity and longitudinal micro-displacement is a power function in the range of 0–100 μm at room temperature with a correlation coefficient of 98.92%. For lateral micro-displacement, the sensitivity is −2.9697 dBm/μm in the range of 0–6 μm with a linear fit of 99.61%. In addition, the linear correlation coefficient decreases as the initial longitudinal distance increases, and the function of these correlation coefficients is also linear with a linearity of 96.14%. This sensor has a simple manufacturing process, low cost, high sensitivity, and fast response speed. It is suitable for harsh environments such as strong electromagnetic interference and corrosivity, and has a broad application prospect in the field of micro-displacement sensing.     

Improved in vitro and in vivo hepatoprotective effects of liposomal silymarin in alcohol-induced hepatotoxicity in Wistar rats

BackgroundSilymarin, a known hepatoprotectant, owing to its poor oral bioavailability, has limited pharmacological effects. The present study was designed to improve its in vitro and in vivo hepatoprotection and increase its oral bioavailability against alcohol intoxication by formulating it in four different liposomal formulations namely conventional, dicetyl phosphate, stearyl amine and PEGylated liposomes.MethodThe liposomes were prepared using phosphatidylcholine, cholesterol, and silymarin in addition to dicetyl phosphate, stearyl amine and DSPE mPEG 2000 by film hydration method with 5% sucrose as a cryo-protectant. The optimized formulations were studied for their release profile at pH 1.2 and 6.8. Liposomes were studied for in vitro protection on Chang liver cells and efficacious liposomes were selected for in vivo hepatoprotection study. Further, conventional liposomes were studied for bioavailability in alcohol intoxicated Wistar rats.ResultsThe conventional liposomes increased in vitro release profile at pH 1.2 and 6.8 and also showed better in vitro protection compared to silymarin alone. Conventional and PEGylated liposomes showed better improvement in liver function, better efficacy in combating inflammatory conditions, better improvement in antioxidant levels and reversal of histological changes compared to silymarin alone. Conventional also showed an almost fourfold increase in area under the curve compared to silymarin suspension.ConclusionConventional and PEGylated liposomes of silymarin were found to be more efficacious as hepatoprotective against alcohol-induced hepatotoxicity by its free radical scavenging and anti-inflammatory effects. Conventional liposomes showed enhanced bioavailability compared to silymarin alone.