response surface optimization
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Chemosphere ◽  
2022 ◽  
Vol 287 ◽  
pp. 132275
Author(s):  
H. Hadiyanto ◽  
Marcelinus Christwardana ◽  
Wahyu Zuli Pratiwi ◽  
P. Purwanto ◽  
S. Sudarno ◽  
...  

2021 ◽  
Vol 37 (6) ◽  
pp. 1462-1474
Author(s):  
Jampana Rama Tulasi ◽  
Avula Prameela Rani ◽  
Panikumar Durga Anumolu

An efficient column friendly, buffer free, highly sensitive, cost effective RP-HPLC method was developed by considering the criticality of different method parameters on analytical attributes like tailing factor, resolution and retention time in preliminary risk analysis and screening designs. The Pareto analysis of screening design highlighted the need for optimization of resolution and its influencers (capacity factor and theoretical plates) for both the drugs to imbibe quality in the method. The suggested method of optimization design was developed using ZODIAC C18 ODS (250 mm × 4.6 mm, 5 μm) column in isocratic mode using mobile phase acetonitrile : methanol : water in the ratio of 60:10:30 at a flow rate of 0.8 mL/min and UV detection wavelength of 262 nm. The retention times of drugs were found to be 3.488 minutes for sofosbuvir, 5.387 minutes for velpatasvir. The linear regression analysis data for the calibration plots showed good linear relationship with r2=0.997 for sofosbuvir, r2=0.988 for velpatasvir, in the working concentration range of 1000-5000 ng/mL, 250-1250 ng/mL respectively. The AQbD devised method was applied for quantification of drugs in plasma and validated as suggested in ICH M10 guidelines.


2021 ◽  
Vol 9 (12) ◽  
pp. 1391
Author(s):  
Kefeng Jiao ◽  
Feihong Yun ◽  
Zheping Yan ◽  
Gang Wang ◽  
Peng Jia ◽  
...  

The sealing performance of the rubber packer is of vital importance for the subsea retractable connector, and the cross-sectional shape of the rubber packer is one of the most important factors affecting it. The compression distance of the rubber packer is increased by 19.54% utilizing the established two-dimensional numerical model. In addition, a new parameter called the anti-shoulder extrusion variable was defined in this paper. Shoulder extrusion will not occur when using this variable as a constraint during simulation. In general, the upper end and the lower end of a rubber packer are subject to different constraints, and the structural parameters of the rubber packer affect each other in terms of sealing performance. Therefore, the importance and originality of this study are exploring the optimization of the thickness and chamfer angles of the upper and lower ends of the rubber packer by use of a combination of the response surface optimization method and the multi-objective genetic algorithm, taking the thickness and chamfer angles of the upper and lower ends as design variables, and the stress on the inner side of the casing wall and the axial force of the compressed rubber packer as optimization objectives. Besides that, the anti-shoulder extrusion variables are also introduced as constraints to prevent shoulder extrusion. Ultimately, the cross-sectional shape of the rubber packer with a smaller-thickness and larger-angle upper end, and a larger-thickness and smaller-angle lower end can be obtained. The result to emerge from the test in this paper is that the pipe pressure that can be sealed by the optimized rubber packer structure is 25.61% higher than that before optimization. The anti-shoulder extrusion variable and the asymmetric cross-sectional shape of the rubber packer proposed in this paper shed new light on the finite element simulation of rubber and the research on similar seals.


2021 ◽  
Author(s):  
Mingluo Zhou ◽  
Riyu Zhou ◽  
Peng Jiang ◽  
Huili Liang ◽  
Yi Zhou ◽  
...  

Abstract Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in-situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84 % removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g/100mL. The CFZ degradation mechanism was studied by the Density Functional Theory (DFT) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe(VI) -clay. Further, DFT calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole and dihydrothiazine rings.


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