Application of derivative ratio spectrophotometry for determination of β-carotene and astaxanthin from Phaffia rhodozyma extract

A derivative ratio spectrophotometric method was used for the simultaneous determination of β-carotene and astaxanthin produced from Phaffia rhodozyma. Absorbencies of a series of the standard carotenoids in the range of 441 nm to 490 nm demonstrated that their absorptive spectra accorded with Beer’s law and that the additivity when the concentrations of β-carotene and astaxanthin and their mixture were within the range of 0 to 5 μg/ml, 0 to 6 μg/ml, and 0 to 6 μg/ml, respectively. When the wavelength interval (?λ) at 2 nm was selected to calculate the first derivative ratio spectra values, the first derivative amplitudes at 461 nm and 466 nm were suitable for quantitatively determining β-carotene and astaxanthin, respectively. Effect of divisor on derivative ratio spectra could be neglected; any concentration used as divisor in range of 1.0 to 4.0 μg/ml is ideal for calculating the derivative ratio spectra values of the two carotenoids. Calibration graphs were established for β-carotene within 0?6.0 μg/ml and for astaxanthin within 0?5.0 μg/ml with their corresponding regressive equations in: y=?0.0082x?0.0002 and y=0.0146x?0.0006, respectively. R-square values in excess of 0.999 indicated the good linearity of the calibration graphs. Sample recovery rates were found satisfactory (>99%) with relative standard deviations (RSD) of less than 5%. This method was suc- cessfully applied to simultaneous determination of β-carotene and astaxanthin in the laboratory-prepared mixtures and the extract from the Phaffia rhodozyma culture.

Diagnostic Method and Adaptability Analysis of Multiple Water Breakthroughs in Horizontal Well in Combined Well Pattern

The combined well pattern has been widely used in reservoir development, with a common pattern being a horizontal well in the center for oil production and multiple vertical wells around for water injection. For this type of well pattern, determining the horizontal well is affected by which injection wells, especially when the injecting water breaks through, accurately determining the direction of water inflow will provide an important basis for targeted water well measures. Based on the production performance data of horizontal wells, the semi logarithmic relationship curves of water-oil ratio, derivative water-oil ratio, and cumulative production were used for the first time to determine the breakthrough problem of water injection in the surrounding water injection wells of horizontal wells based on their response characteristics. The adaptability of this method under different influencing factors was analyzed. Introducing the parameter of cumulative production not only preserves the variation trend of the derivative of water-oil ratio with time, but also facilitates the processing of actual production data.

Utility of preoperative systemic inflammatory biomarkers in predicting postoperative complications after pancreaticoduodenectomy: Literature review and single center experience

BACKGROUND The role of preoperative inflammatory biomarkers(PIBs)in predicting postoperative morbidity has been assessed in colorectal and otorhinolaryngeal surgery.However,data regarding the role that preoperative inflammatory biomarkers have on morbidity after pancreaticoduodenectomiy(PD)are less consistent.AIM To assess the utility of PIBs in predicting postoperative complications after pancreaticoduodenectomy.METHODS A database of 317 consecutive pancreaticoduodenectomies performed from April 2003 to November 2018 has been retrospectively analyzed.Data regarding preoperative neutrophil-to-lymphocyte ratio(NLR),derived NLR and C-reactive protein(CRP),and postoperative complications of 238 cases have been evaluated.Exclusion criteria were:age<18-years-old,previous neoadjuvant treatment,absence of data about PIBs,concomitant hematological disorders,and presence of active infections at the moment of the surgery.PIBs were compared using Mann-Whitney’s test and receiver operating characteristic(ROC)analysis was performed to define the cutoffs.The positive predictive value(PPV)was computed to evaluate the probability to develop complication.P-values<0.05 were considered statistically significant.RESULTS According to the literature findings,only four papers have been published reporting the relation between the inflammatory biomarkers and PD postoperative morbidity.A combination of preoperative and postoperative inflammatory biomarkers in predicting complications after PD and the utility of preoperative NLR in the development of postoperative pancreatic fistula(POPF)have been reported.The combination of PIBs and postoperative day-1 drains amylase has been reported to predict the incidence of POPF.According to our results,CRP values were significantly different between patients who had/did not have postoperative complications and abdominal collections(P<0.05).Notably,patients with preoperative CRP>8.81 mg/dL were at higher risk of both overall complications and abdominal collections(respectively P=0.0037,PPV=0.95,negative predictive value[NPV]=0.27 and P=0.016,PPV=0.59,NPV=0.68).Preoperative derived neutrophil-to-lymphocyte ratio(dNLR)(cut off>1.47)was also a predictor of abdominal collection(P=0.021,PPV=0.48,NPV=0.71).Combining CRP and dNLR,PPV increased to 0.67.NLR(cut off>1.65)was significantly associated with postoperative hemorrhage(P=0.016,PPV=0.17,NPV=0.98).CONCLUSION PIBs may predict complications after PD.During postoperative care,PIB levels could influence decisions regarding the timing of drains removal and the selection of patients who might benefit from second level diagnostic exams.