Modification of polyvinylidene fluoride membrane with ciprofloxacin to improve the bacteriostatic performance.

The common polyvinylidene fluoride (PVDF) membrane itself is susceptible to membrane fouling, especially biofouling, which is a serious threat. In this study, PVDF membrane was modified with ciprofloxacin (CIP) through co-blending to investigate the filtration properties, bacterial inhibition and fouling resistance. Modified membranes were prepared by adding 0.3 g (MC0.3), 0.6 g (MC0.6), 0.9 g (MC0.9) and 1.2 g (MC1.2) CIP per 100 g casting solution. Among these modified membranes, MC0.6 showed the best filtration performances, with the pure water flux stabilized at about 416.67 L/(m2·h) and bovine serum albumin (BSA) rejection of 92.0% at a trans-membrane pressure of 0.1 MPa. The pore size was reduced, the average roughness was reduced to 29.4 nm, the contact angle was lowered to 68.9°, and the hydrophilicity was greatly improved. The width of the inhibition circle produced by MC0.6 was 0.35-0.45 mm, and the modified membrane showed good inhibition of non-specific bacteria and algal removal during urban river water filtration. The rejection of BSA was increased by 16.32% compared to the base membrane and the adsorption rate for BSA was reduced by 68.45%. In addition, the removal of conventional pollutants in urban river water by the modified membranes for was also improved. Compared with that of the base membrane, the removal of TN, NH3-N, TP and COD by MC0.6 was increased by 10.58%, 12.45%, 15.44% and 13.53%. The results showed that CIP co-blending modified PVDF membrane could effectively improve membrane performances and has good value for water treatment.

Sensitivity Analysis of RV Reducer Rotation Error Based on Deep Gaussian Processes.

The rotation error is the most important quality characteristic index of a rotate vector (RV) reducer, and it is difficult to accurately optimize the design of a RV reducer, such as the Taguchi type, due to the many factors affecting the rotation error and the serious coupling effect among the factors. This paper analyzes the RV reducer rotation error and each factor based on the deep Gaussian processes (DeepGP) model and Sobol sensitivity analysis(SA) method. Firstly, using the optimal Latin hypercube sampling (OLHS) approach and the DeepGP model, a high-precision regression prediction model of the rotation error and each affecting factor was created. On the basis of the prediction model, the Sobol method was used to conduct a global SA of the factors influencing the rotation error and to compare the coupling relationship between the factors. The results show that the OLHS method and the DeepGP model are suitable for predicting the rotation error in this paper, and the accuracy of the prediction model constructed based on both of them is as high as 95%. The rotation error mainly depends on the influencing factors in the second stage cycloidal pinwheel drive part. The primary involute planetary part and planetary output carrier's rotation error factors have little effect. The coupling effects between the matching clearance between the pin gear and needle gear hole (δJ) and the circular position error of the needle gear hole (δt) is noticeably stronger.

Experimental study of acute organophosphorus compound poisoning in rabbit kidneys by ultrasonic tissue characterization.

OBJECTIVE: The purpose of this study was to investigate the value of integrated backscatter (IBS) of kidneys in acute organophosphorus compound poisoning in rabbits. METHODS: Eighteen rabbits were poisoned by dimethyl dichlorovinyl phosphate to establish animal models. Sonographic examinations were performed before (T0) and after (T1-T9) the rabbits were poisoned. The echo and size of kidneys were evaluated by 2-dimensional gray scale sonography. Changes of the renal cortex and medulla were analyzed quantitatively with IBS. RESULTS: No change of the cortex echo was found before and after poisoning. A significant change of the volume of kidneys on both sides began at T6 compared with that at T0 (P < .05). A significant change of renal length on both sides began at T7 compared with that at T0 (P < .05). The volume change was earlier than that of length. A significant change in IBS% of the renal cortex began at T5 compared with that at T0 (P < .05), whereas a significant change in IBS% of the renal medulla began at T6 compared with that at T(0) (P < .05). The change in IBS% of the renal cortex was earlier. CONCLUSIONS: More useful information provided by IBS% has been found in acute organophosphorus compound poisoning in rabbits.