Modification of nanoparticles for the strength enhancing of cementstabilized dredged sludge

This paper investigates the effectiveness of nano-modification on the strength enhancement of cementstabilized dredged sludge(CDS).Three types of nanoparticles including nano-SiO2(NS),nano-Al2O3(NA)and nano-MgO(NM)were used as cement admixtures for dredged sludge stabilization.Effects of single nanoparticle content,mass ratio of composite nanoparticles and curing time on the strength development of CDS were evaluated via a series of unconfined compressive strength(UCS)tests.The pH evolutions of CDS caused by nanoparticles were also examined by a range of pH tests.Furthermore,micromechanisms reflecting the strength evolutions were analyzed by performing scanning electron microscopy(SEM)and X-ray diffraction(XRD)tests.The results indicated that adding nanoparticles can significantly improve the UCS of CDS.For single nano-modification,the optimum contents of NS,NA and NM were 4%e6%,6%and 8%,which can increase the 7-and 28-d UCSs of CDS by 38%and 50%,17%and 35%,65%and 67%,respectively.Compared with single nano-modification,composite nano-modifications were more effective in improving the strength gain of CDS.The optimum mass ratios of composite nanoparticles,namely NS/NA,NS/NM and NA/NM,were 9/1,3/7 and 3/7,respectively.Based on the strength growth rate,the composite nanoparticles with NS/NM of 3/7 were highly recommended.The addition of nanoparticles obviously affected the pH evolution of CDS,which was mainly determined by the difference of OHproduction and consumption inside nano-modified CDS.The microstructural analysis revealed that C-S-H and C-A-H gels are the main cementitious products,and the addition of nanoparticles can obviously contribute to a denser and more homogenous microstructure of CDS.

Relationship between symptom response and esophageal pH level on standard dose of esomeprazole treatment for gastroesophageal reflux disease

Background The relationship between symptom elimination and normalization of esophageal acid level of gastroesophageal reflux disease （GERD） on proton-pump inhibitor （PPI） therapy has been questioned. This study aimed to evaluate the relationship between symptom response and gastro-esophageal acidity control in Chinese patients with GERD on esomeprazole therapy, and to assess the role of 24-hour esophageal pH-metry after therapy in GERD patients.Methods GERD patients with typical reflux symptoms were enrolled and received esomeprazole 40 mg once daily for 4 weeks. Patients with positive baseline 24-hour esophageal pH-metry were divided into two groups depending on an additional dual-channel 24-hour pH-metry after treatment. The pH- group achieved normalization of esophageal pH level whereas the pH＋ group did not.Results Of the 80 patients studied, 76 had abnormal baseline esophageal pH levels. Of these, 90% （52/58） of symptom-free patients and 67% （12/18） of symptom-persistent patients achieved esophageal pH normalization after therapy （P=0.030）. The mean post-therapy gastric nocturnal percent time of pH 〈4.0 was significantly higher in pH＋group than that in pH- group （P 〈0.001） after therapy. The multivariate regression analysis identified hiatus hernia （P〈0.001） and persistent reflux symptom （P=0.004） were two independent factors predicting the low post-therapy esophageal pH level.Conclusions Symptom elimination is not always accompanied by esophageal pH normalization, and vice verse.Esophageal pH-metry is recommended for GERD patients with hiatus hernia or with persistent reflux symptoms after PPI therapy.