Limits Of Detection Of A Total Reflection X-ray Fluorescence System With Double Reflection Module

An X-ray tube with a Mo target and Zr filter, operated at 45 kV/20 mA, was used to excite samples (5 μL deposited on a quartz support) and the total reflection angle condition was obtained with a double reflector module built with two 10-cm-long 7-mm-thick quartz crystals placed 50 μm apart. A high-resolution spectrometer based on a Si(Li) detector coupled to a multichannel analyzer was used for X-ray detection and the spectra were interpreted with the AXIL software. The system was calibrated with standard chemical solutions containing Cr, Fe, Cu, Zn, and Pb, and Y was used as an internal standard to correct eventual geometric errors and high-voltage instabilities of the X-ray generator. The limits of detection were 19, 9, 5, and 4 ng/mL for Cr, Fe, Cu, and Zn, respectively, analyzed through characteristic K(α) X-rays, and 7 ng/mL for Pb, through L(α) X-rays, considering 50 μL samples deposited and dried on a quartz support, to be excited/detected for 1000 s.71-72423430Yoneda, Y., Horiuchi, T., Optical flats for use in X-ray spectrochemical micro-analysis (1971) Rev. Sci. Instrum., 42, p. 1069Aiginger, H., Wobrauschek, P., A method for quantitative X-ray fluorescence analysis in the nanogram region (1974) Nucl. Instrum. Methods, 114, pp. 157-158Wobrauschek, P., Aiginger, H., Total reflection fluorescence spectrometric determination of elements in ng amounts (1975) Anal. Chem., 47, pp. 852-855Koopmann, C., Prange, A., Multielement determination in sediments from the German Wadden Sea - Investigations on sample preparation techniques (1991) Spectrochim. Acta, 46 B, pp. 1395-1402Poblete, V.H., (1996), p. 48. , Ph.D. Thesis, Facultad de Ciencias Físicas y Matematicas, Universidad de Chile, Santiago, Chile Chap. IIIAiginger, H., Historical development and principles of total reflection X-ray fluorescence analysis (TXRF) (1991) Spectrochim. Acta, 46 B, pp. 1313-1321Prange, A., Schwenke, H., Trace element analysis using total-reflection X-ray fluorescence spectrometry (1992) Adv. X-Ray Anal., 35, pp. 899-923Ladisich, W., Rieder, R., Wobrauschek, P., Quantitative total reflection X-ray fluorescence analysis with monoenergetic excitation (1994) X-ray Spectrom., 23, pp. 173-177Klockemkämper, R., Von Bohlen, A., Elemental analysis of environmental samples by total reflection fluorescence: A review (1996) X-ray Spectrom., 25, pp. 156-162Curie, L.A., Limits for quantitative detection and quantitative determination (1968) Anal. Chem., 40, pp. 586-593Ladisich, W., Rieder, R., Wobrauschek, P., Aiginger, H., Total reflection X-ray fluorescence analysis with monoenergetic excitation using rotating anode X-ray tubes (1993) Nucl. Instrum. Methods Phys. Res., 330 A, pp. 501-50

Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery

Background: Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery. Methods: A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury. Results: A total of 4164 patients were included, with a median age of 68 (i.q.r. 57\u201375) years (54\ub79 per cent men). Some 1153 (27\ub77 per cent) received NSAIDs on postoperative days 1\u20133, of whom 1061 (92\ub70 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4\ub76 versus 4\ub78 days; hazard ratio 1\ub704, 95 per cent c.i. 0\ub796 to 1\ub712; P = 0\ub7360). There were no significant differences in anastomotic leak rate (5\ub74 versus 4\ub76 per cent; P = 0\ub7349) or acute kidney injury (14\ub73 versus 13\ub78 per cent; P = 0\ub7666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35\ub73 versus 56\ub77 per cent; P < 0\ub7001). Conclusion: NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement