Abstract The surfactant-polymer-based (S/P) fracturing fluid combines the advantages of the surfactant-based and polymer-based fracturing fluids. In this study, the synergistic tackifying of cationic surfactants and carboxymethyl hydroxyethyl cellulose and the potential application in hydraulic fracturing fluid was investigated. Firstly, cetyltrimethylammonium chloride (CTAC) and salicylic acid (SA) with a weight ratio of 4:1 were optimized as the main agent of the small molecule surfactant gel, which was then mixed with carboxymethyl 2-hydroxyethyl ether cellulose (CMHEC) and salicylic acid (SA) to obtain the S/P gel. The proppant suspension performance, gel-breaking properties, salt-resistance and thermal stability of the optimized S/P were evaluated to confirm their potential application in the hydraulic fracturing fluid. These results showed that the performance of the S/P fracturing fluid system was much better than the performance of the surfactant fracturing fluid and also the performance of polymer fracturing fluid.

RESUMO - RACIONAL: A pancreatectomia laparoscópica está se tornando uma abordagem amplamente usada para lesões benignas e malignas do pâncreas. OBJETIVOS: Descrever como realizar a pancreatectomia distal laparoscópica usando a Clockwise Technique. MÉTODOS: Paciente feminina com 18 anos de idade, apresentando tumor bem definido no corpo pancreático com 4 cm de diâmetro que sugeria o diagnóstico de tumor sólido pseudopapilar (tumor de Frantz). O paciente foi considerado para pancreatectomia distal laparoscópica pela Clockwise Technique. RESULTADOS: A Clockwise Technique parece apresentar outras vantagens técnicas significativas que facilitam a realização do procedimento. CONCLUSÕES: A pancreatectomia distal laparoscópica foi realizada com a clockwise technique, obtendo-se resultados satisfatórios.

ABSTRACT - BACKGROUND: Laparoscopic pancreatectomy is currently a widely used approach for benign and malignant lesions of the pancreas. AIMS: This study aimed to describe how to perform a laparoscopic distal pancreatectomy using The Clockwise Technique. METHODS: An 18-year-old female patient presented with a well-defined tumor in the pancreatic body with 4 cm in diameter that suggested a diagnosis of solid pseudopapillary tumor (Frantz’s tumor). The patient was recommended for laparoscopic distal pancreatectomy by using The Clockwise Technique. RESULTS: The clockwise, caudal-to-cephalic approach appears to have other significant technical advantages that facilitate the performance of the procedure. CONCLUSIONS: A laparoscopic distal pancreatectomy performed using The Clockwise Technique provides satisfactory outcomes.

Abstract: Poly(aspartic acid-citric acid) copolymer (PAC) is a new product of poly(carboxylic acid) scale inhibitor. The study aims to develop a "green" water treatment agent for calcium phosphate scale. The article compares the efficiency of three polymeric antiscalants, poly(aspartic acid-citric acid) copolymer (PAC), polymaleic acid (HPMA) and a compound inhibitor (PAC-HPMA), for calcium phosphate scale prevention under varying experimental conditions. Inhibitor concentration, calcium concentration, system pH, temperature and experimental time were varied to determine their influences on inhibitor performance by the static scale inhibition method. The copolymer (PAC) was characterized by FTIR, 1H NMR and 13C NMR. The compound inhibitor was applied in the actual circulating cooling water system. An atomic force microscope (AFM), X-ray powder diffraction (XRD) and a scale formation process analysis were used to explore the scale inhibition mechanism. The results showed that scale inhibition rates of PAC, HPMA and PAC-HPMA against Ca3(PO4)2 were, respectively, about 23%, 41.5% and 63% when the dosage was 8 mg/L in the experiment. The compound inhibitor showed the better inhibition performance than the above two kinds of monomers. Under the actual working conditions, the inhibition rate of compound inhibitor was close to 100% and completely met the actual application requirements of scale inhibitor in circulating cooling water systems. The main inhibition mechanism was the decomposition-chelation dispersion effect. The compound inhibitor can be used as an efficient "green" scale inhibitor for calcium phosphate.

The quantitative structure property relationship (QSPR) for the boiling point (Tb) of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) was investigated. The molecular distance-edge vector (MDEV) index was used as the structural descriptor. The quantitative relationship between the MDEV index and Tb was modeled by using multivariate linear regression (MLR) and artificial neural network (ANN), respectively. Leave-one-out cross validation and external validation were carried out to assess the prediction performance of the models developed. For the MLR method, the prediction root mean square relative error (RMSRE) of leave-one-out cross validation and external validation was 1.77 and 1.23, respectively. For the ANN method, the prediction RMSRE of leave-one-out cross validation and external validation was 1.65 and 1.16, respectively. A quantitative relationship between the MDEV index and Tb of PCDD/Fs was demonstrated. Both MLR and ANN are practicable for modeling this relationship. The MLR model and ANN model developed can be used to predict the Tb of PCDD/Fs. Thus, the Tb of each PCDD/F was predicted by the developed models.

The application of automated correlation optimized warping (ACOW) to the correction of retention time shift in the chromatographic fingerprints of Radix Puerariae thomsonii (RPT) was investigated. Twenty-seven samples were extracted from 9 batches of RPT products. The fingerprints of the 27 samples were established by the HPLC method. Because there is a retention time shift in the established fingerprints, the quality of these samples cannot be correctly evaluated by using similarity estimation and principal component analysis (PCA). Thus, the ACOW method was used to align these fingerprints. In the ACOW procedure, the warping parameters, which have a significant influence on the alignment result, were optimized by an automated algorithm. After correcting the retention time shift, the quality of these RPT samples was correctly evaluated by similarity estimation and PCA. It is demonstrated that ACOW is a practical method for aligning the chromatographic fingerprints of RPT. The combination of ACOW, similarity estimation, and PCA is shown to be a promising method for evaluating the quality of Traditional Chinese Medicine.