A sludge volume index (SVI) model based on the multivariate local quadratic polynomial regression method

In this study, a multivariate local quadratic polynomial regression(MLQPR) method is proposed to design a model for the sludge volume index(SVI). In MLQPR, a quadratic polynomial regression function is established to describe the relationship between SVI and the relative variables, and the important terms of the quadratic polynomial regression function are determined by the significant test of the corresponding coefficients. Moreover, a local estimation method is introduced to adjust the weights of the quadratic polynomial regression function to improve the model accuracy. Finally, the proposed method is applied to predict the SVI values in a real wastewater treatment process(WWTP). The experimental results demonstrate that the proposed MLQPR method has faster testing speed and more accurate results than some existing methods.

Left Atrial Volume Index in Patients with Dilated Cardiomyopathy—Correlation with Left Ventricular Function

Background: The aim of this study was to determine the relation of left atrial (LA) volume and LA volume index with left ventricular function and to determine the association of duration of symptoms and left atrial volume index in patients with dilated cardiomyopathy. Materials and Methods: This was an observational, single centre study conducted in India. A total of 50 patients who were admitted to department of cardiology from July, 2008 to February, 2009 with diagnosis of dilated cardiomyopathy and an ejection fraction of <40% were included. Results: Of the 50 patients, 34 (68%) were males. 27 (54%) patients were in NYHA class II and 23 (46%) patients were in NYHA class III. LA volume was found to be ≥40 ml in all patients. LV function and LA volume were found to be correlated (r = -0.789, p < 0.01). Similarly, there was a correlation between LV function and LA volume index (r = -0.826, p < 0.01). There was no correlation between LA volume index and duration of symptoms (r = 0.04). Conclusion: It can be concluded that there is a strong inverse correlation between LA volume and left ventricular function and also between LA volume index and left ventricular function. The patients with NYHA class III were having larger left atrial volume than those with NYHA class II. Moreover, the duration of symptoms has no correlation with left atrial volume index.

Implications of left atrial volume index in patients with three-vessel coronary disease:A 6.6-year follow-up cohort study

Background:Risk assessment and treatment stratification for three-vessel coronary disease(TVD)remain challenging.This study aimed to investigate the prognostic value of left atrial volume index(LAVI)with the Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery(SYNTAX)score II,and its association with the long-term prognosis after three strategies(percutaneous coronary intervention[PCI],coronary artery bypass grafting[CABG],and medical therapy[MT])in patients with TVD.Methods:This study was a post hoc analysis of a large,prospective cohort of patients with TVD in China,that aimed to determine the long-term outcomes after PCI,CABG,or optimal MT alone.A total of 8943 patients with TVD were consecutively enrolled between 2004 and 2011 at Fuwai Hospital.A total of 7818 patients with available baseline LAVI data were included in the study.Baseline,procedural,and follow-up data were collected.The primary endpoint was major adverse cardiac and cerebrovascular events(MACCE),which was a composite of all-cause death,myocardial infarction(MI),and stroke.Secondary endpoints included all-cause death,cardiac death,MI,revascularization,and stroke.Long-term outcomes were evaluated among LAVI quartile groups.Results:During a median follow-up of 6.6 years,a higher LAVI was strongly associated with increased risk of MACCE(Q3:hazard ratio[HR]1.20,95%confidence interval[CI]1.06-1.37,P=0.005;Q4:HR 1.85,95%CI 1.64-2.09,P<0.001),all-cause death(Q3:HR 1.41,95%CI 1.17-1.69,P<0.001;Q4:HR 2.54,95%CI 2.16-3.00,P<0.001),and cardiac death(Q3:HR 1.81,95%CI 1.39-2.37,P<0.001;Q4:HR 3.47,95%CI 2.71-4.43,P<0.001).Moreover,LAVI significantly improved discrimination and reclassification of the SYNTAX score II.Notably,there was a significant interaction between LAVI quartiles and treatment strategies for MACCE.CABG was associated with lower risk of MACCE than MT alone,regardless of LAVI quartiles.Among patients in the fourth quartile,PCI was associated with significantly increased risk of cardiac death compared with CABG(HR:5.25,95%CI:1.97-14.03,P=0.001).Conclusions:LAVI is a potential index for risk stratification and therapeutic decision-making in patients with three-vessel coronary disease.CABG is associated with improved long-term outcomes compared with MT alone,regardless of LAVI quartiles.When LAVI is severely elevated,PCI is associated with higher risk of cardiac death than CABG.

Differences in Heart Stroke Volume between Han and Korean-Chinese Nationalities and Correlative Factors

Objective To compare the differences in stroke volume （SV） and stroke volume index （Sl） between Han and Korean-Chinese and to investigate the correlated risk factors. Methods A total of 1 647 Han and 876 Korean-Chinese aged 10-80 years were investigated. SV, SI, cardiac output, cardiac output index, heart rate （HR）, systemic vascular resistance （SVR）, systemic vascular resistance index （SVRI）, and blood pressure were measured. Results SV/SI values in Korean-Chinese were lower than those in the Han of the same sex and age. Covariance analysis showed that, apart from the effect of sex, age and body mass index （BMI）, the differences in SV and SI between the two cohorts were still significant （P〈O.O01）. Multiple regression analysis revealed that the SV difference between the two ethnicities was affected （in descending order from a strong to weak correlation） by SVR, SVRI, HR, diastolic blood pressure, mean arterial pressure, BMI, and systolic blood pressure, while the SI difference was affected by SVR, SVRI, HR, mean arterial pressure, diastolic and systolic blood pressure, and BMI. Conclusion The Fact that SV and SI in Korean-Chinese are lower than those in Han is related with higher SVR, HR and blood pressure in the Korean-Chinese.

Passive leg raising as an indicator of fluid responsiveness in patients with severe sepsis

In the management of critically ill patients, the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians. Static indices of cardiac preload are poor predictors of volume responsiveness. Passive leg raising （PLR） mimics an endogenous volume expansion （VE） that can be used to predict fluid responsiveness. This study was to assess the changes in stroke volume index （SVI） induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis. This was a prospective study. Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital, Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011. Patients with non-sinus rhythm or arrhythmia, parturients, and amputation of the lower limbs were excluded. Measurements of SVI were obtained in a semi-recumbent position （baseline） and during PLR by the technique of pulse indicator continuous cardiac output （PiCCO） system prior to VE. Measurements were repeated after VE （500 mL 6% hydroxyethyl starch infusion within 30 minutes） to classify patients as either volume responders or non-responders based on their changes in stroke volume index （ASVI） over 15%. Heart rate （HR）, systolic artery blood pressure （ABPs）, diastolic artery blood pressure （ABPd）, mean arterial blood pressure （ABPm）, mean central venous pressure （CVPm） and cardiac index （CI） were compared between the two groups. The changes ofABPs, ABPm, CVPm, and SVI after PLR and VE were compared with the indices at the baseline. The ROC curve was drawn to evaluate the value of ASVI and the change of CVPm （ACVPm） in predicting volume responsiveness. SPSS 17.0 software was used for statistical analysis. Among the 32 patients, 22 were responders and 10 were non-responders. After PLR among the responders, some hemodynamic variables （including ABPs, ABPd, ABPm and CVPm） were significantly elevated （101.2±17.6 vs. 118.6±23.7, P=0.03; 52.8±10.7 vs. 64.8±10.7, P=0.006; 68.3±11.7 vs. 81.9±14.4, P=0.008; 6.8±3.2 vs. 11.9±4.0, P=0.001）. After PLR, the area under curve （AUC） and the ROC curve of ASVI and ACVPm for predicting the responsiveness after VE were 0.882±0.061 （95%CI 0.759-1.000） and 0.805±0.079 （95%CI 0.650-0.959） when the cut-off levels of ASVI and ACVPm were 8.8% and 12.7%, the sensitivities were 72.7% and 72.7%, and the specificities were 80% and 80%. Changes in ASVI and ACVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.

Control of sludge settleability and nitrogen removal under low dissolved oxygen condition

Low dissolved oxygen （DO） is an energy- saving condition in activated sludge process. To investi- gate the possible application of limited filamentous bulking （LFB） in sequencing batch reactor （SBR）, two lab-scale SBRs were used to treat synthetic domestic wastewater and real municipal wastewater, respectively. The results showed that prolonging low DO aeration duration and setting pre-anoxic （anaerobic） phase were effective strategies to induce and inhibit filamentous sludge bulking, respectively. According to the sludge settleability, LFB could be maintained steadily by adjusting operation patterns. Filamentous bacteria content and sludge volume index （SVI） were likely correlated. SVI fluctuated dramatically within a few cycles when around 200 mL-g~, where altering operation pattern could change sludge settleability in spite of the unstable status of activated sludge system. Energy consumption by aeration reduced under low DO LFB condition, whereas the nitrification performance deteriorated. However, short-cut nitrification and simultaneous nitrification denitrification （SND） were prone to take place under such conditions. When the cycle time kept constant, the anoxic （anaerobic） to aerobic time ratio was determining factor to the SND efficiency. Similarity keeping aerobic time as constant, the variation trends of SND efficiency and specific SND rate were uniform. SBR is a promising reactor to apply the LFB process in practice.

Low intensity ultrasound stimulates biological activity of aerobic activated sludge

This work aims to explore a procedure to improve biological wastewater treatment efficiency using low inten-sity ultrasound.The aerobic activated sludge from a munici-pal wastewater treatment plant was used as the experimental material.Oxygen uptake rate(OUR)of the activated sludge(AS)was determined to indicate the changes of AS activity stimulated by ultrasound at 35 kHz for 0-40 min with ultrasonic intensities of 0-1.2 W/cm^(2).The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm^(2) and an irradiation period of 10 min;more than 15%increase was achieved immediately after sonication.More significantly,the AS activity stimulated by ultrasound could last 24 h after sonication,and the AS activity achieved its peak value within 8 h after sonication,or nearly 100%higher than the initial level after sonication.Therefore,to improve the wastewater treatment efficiency of bioreactors,ultrasound with an intensity of 0.3 W/cm^(2) could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.