Effect of pH and added slag on the extractability of Si in two Si-deficient sugarcane soils

The effects of increasing pH on the adsorption and extractability of Si in two Si-deficient Australian sugarcane soils was investigated and the effects of increasing rates of fertilizer Si (as blast furnace slag) on pH and extractable Si were also examined. Equilibrium studies showed that maximum adsorption of Si by the two soils occurred in the pH range 9-10. When soil pH was increased from 5.0 to 6.5, subsequent adsorption of Si by the two soils, as measured by adsorption isotherms, increased. After incubation with progressive lime additions there was a decline in CaCl2- extractable Si due to its increased adsorption and an increase in acid (H2SO4- and acetic acid)-extractable (mainly adsorbed) Si. The increase in acid extractable Si was greater than the decrease in CaCl2- extractable Si suggesting a supply from an additional source. Alkali (Na2CO3 and Tiron)-extractable Si decreased greatly with increasing pH suggesting dissolution of the amorphous (mainly biogenic) pool of silica was occurring with increasing pH. When increasing rates of slag were incubated with the soils, pH, CaCl2- and acid- extractable Si were all increased because upon dissolution slags release both silicic acid and OH- ions. There was, therefore, a positive relationship between extractable Si and soil pH. However, Na2CO3-and Tiron-extractable Si decreased with increasing slag rates (and increasing soil pH) suggesting dissolution of the biogenic pool of soil Si. It was concluded that future research needs to examine the desorption potential of adsorbed Si and the effects of liming on dissolution of the biogenic pool of soil silica under field conditions

Vibrational spectroscopy at electrolyte/electrode interfaces with graphene gratings.

Microscopic understanding of physical and electrochemical processes at electrolyte/electrode interfaces is critical for applications ranging from batteries, fuel cells to electrocatalysis. However, probing such buried interfacial processes is experimentally challenging. Infrared spectroscopy is sensitive to molecule vibrational signatures, yet to approach the interface three stringent requirements have to be met: interface specificity, sub-monolayer molecular detection sensitivity, and electrochemically stable and infrared transparent electrodes. Here we show that transparent graphene gratings electrode provide an attractive platform for vibrational spectroscopy at the electrolyte/electrode interfaces: infrared diffraction from graphene gratings offers enhanced detection sensitivity and interface specificity. We demonstrate the vibrational spectroscopy of methylene group of adsorbed sub-monolayer cetrimonium bromide molecules and reveal a reversible field-induced electrochemical deposition of cetrimonium bromide on the electrode controlled by the bias voltage. Such vibrational spectroscopy with graphene gratings is promising for real time and in situ monitoring of different chemical species at the electrolyte/electrode interfaces

Effects of Polypyrrole/Graphene Oxide Composites with Different Reaction Times on Electrochemical Performance

Graphene oxide (GO) was prepared using the modified Hummers method and used as a template for polypyrrole. Polypyrrole was polymerized in situ on the surface of GO to finally obtain the polypyrrole/graphene oxide composite material. The effects of different reaction times on the electrochemical performance of polypyrrole/graphene oxide in the second step were studied. It was obtained that the composite material had optimal properties when the reaction time was 24 h

Pharmacokinetic/Pharmacodynamic Correlation of Cefquinome Against Experimental Catheter-Associated Biofilm Infection Due to Staphylococcus aureus.

Biofilm formations play an important role in Staphylococcus aureus pathogenesis and contribute to antibiotic treatment failures in biofilm-associated infections. The aim of this study was to evaluate the pharmacokinetic/pharmacodynamic (PK/PD) profiles of cefquinome against an experimental catheter-related biofilm model due to S. aureus, including three clinical isolates and one non-clinical isolate. The minimal inhibitory concentration (MIC), minimal biofilm inhibitory concentration (MBIC), biofilm bactericidal concentration (BBC), minimal biofilm eradication concentration (MBEC) and biofilm prevention concentration (BPC) and in vitro time-kill curves of cefquinome were studied in both planktonic and biofilm cells of study S. aureus strains. The in vivo post-antibiotic effects (PAEs), PK profiles and efficacy of cefquinome were performed in the catheter-related biofilm infection model in murine. A sigmoid E max model was utilized to determine the PK/PD index that best described the dose-response profiles in the model. The MICs and MBICs of cefquinome for the four S. aureus strains were 0.5 and 16 μg/mL, respectively. The BBCs (32-64 μg/mL) and MBECs (64-256 μg/mL) of these study strains were much higher than their corresponding BPC values (1-2 μg/mL). Cefquinome showed time-dependent killing both on planktonic and biofilm cells, but produced much shorter PAEs in biofilm infections. The best-correlated PK/PD parameters of cefquinome for planktonic and biofilm cells were the duration of time that the free drug level exceeded the MIC (fT > MIC, R (2) = 96.2%) and the MBIC (fT > MBIC, R (2) = 94.7%), respectively. In addition, the AUC24h/MBIC of cefquinome also significantly correlated with the anti-biofilm outcome in this model (R (2) = 93.1%). The values of AUC24h/MBIC for biofilm-static and 1-log10-unit biofilm-cidal activity were 22.8 and 35.6 h; respectively. These results indicate that the PK/PD profiles of cefquinome could be used as valuable guidance for effective dosing regimens treating S. aureus biofilm-related infections

Badanie zależności między metylacją regionu promotora genu MMP-9 a nefropatią cukrzycową

Objective: This study aims to explore the relationship between the methylation of matrix metalloproteinase (MMP)-9 gene promoter region and diabetic nephropathy (DN) through the detection of the methylation level of MMP-9 gene promoter region in the peripheral blood of patients with DN in different periods and serum MMP-9 concentration. Methods: The methylation level of the MMP-9 gene promoter region was detected by methylation-specific polymerase chain reaction (MSP), and the content of MMP-9 in serum was determined by enzyme-linked immunosorbent assay (ELISA). Results: Results of the statistical analysis revealed that serum MMP-9 protein expression levels gradually increased in patients in the simple diabetic group, early diabetic nephropathy group and clinical diabetic nephropathy group, compared with the control group; and the difference was statistically significant (P < 0.05). Compared with the control group, the methylation levels of MMP-9 gene promoter regions gradually decreased in patients in the simple diabetic group, early diabetic nephropathy group, and clinical diabetic nephropathy group; and the difference was statistically significant (P < 0.05). Furthermore, correlation analysis results indicated that the demethylation levels of the MMP-9 gene promoter region was positively correlated with serum protein levels, urinary albumin to creatinine ratio (UACR), urea and creatinine; and was negatively correlated with GFR. Conclusion: The demethylation of the MMP-9 gene promoter region may be involved in the occurrence and development of diabetic nephropathy by regulating the expression of MMP-9 protein in serum.Wstęp: Celem pracy jest zbadanie zależności między metylacją regionu promotora genu metaloproteinazy macierzy zewnątrzkomórkowej typu 9 a nefropatią cukrzycową, poprzez wykrycie poziomu metylacji regionu promotora genu MMP-9 we krwi obwodowej pacjentów z nefropatią cukrzycową w różnych okresach i przy różnym stężeniu MMP-9 w surowicy krwi. Materiał i metody: Poziom metylacji regionu promotora genu MMP-9 wykrywano za pomocą metylospecyficznej reakcji łańcuchowej polimerazy (methylation-specific polymerase chain reaction; MSP), natomiast zawartość MMP-9 w surowicy krwi była określana przy użyciu enzymatycznego testu immunoadsorpcyjnego (ELISA). Wyniki: Wyniki analizy statystycznej wykazały, że poziom ekspresji białka MMP-9 w surowicy krwi stopniowo wzrastał w grupie pa­cjentów ze zwykłą cukrzycą, w grupie pacjentów z wczesną nefropatią cukrzycową oraz w grupie z kliniczną nefropatią cukrzycową w porównaniu z grupą kontrolną; różnica była statystycznie istotna (p &lt; 0,05). W porównaniu z grupą kontrolną poziom metylacji regionów promotora genu MMP-9 stopniowo się zmniejszał w grupie pacjentów ze zwykłą cukrzycą, w grupie pacjentów z wczesną nefropatią cukrzycową oraz w grupie z kliniczną nefropatią cukrzycową; różnica była istotna statystycznie (p &lt; 0,05). Ponadto, wyniki analizy korelacji wykazały, że poziomy demetylacji regionu promotora genu MMP-9 były dodatnio skorelowane ze stężeniem białek w surowicy krwi, ze wskaźnikiem albumina/kreatynina (urinary albumin to creatinine ratio; UACR), mocznikiem i kreatyniną oraz były ujemnie skorelowane ze wskaźnikiem GFR. Wnioski: Demetylacja regionu promotora genu MMP-9 może być zaangażowana w występowanie i rozwój nefropatii cukrzycowej poprzez regulację ekspresji białka MMP-9 w surowicy krwi.