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Graphitic carbon nitride (g‐C3N4) assisted photocatalytic production of hydrogen peroxide (H2O2 has already attracted the interest of many researchers due to its environmental sustainability. Nevertheless, the inherent drawbacks of g‐C3N4 limit its progress. Metal‐free modification strategies, including nanostructure design, defect introduction, doping, and heterojunction construction, have been developed to improve the efficiency of g‐C3N4 photocatalytic H2O2 production. Compared to metal modification, metal‐free strategies avoid the use of precious metals and the leaching of heavy metal ions, which have the advantages of good stability and environmental friendliness. However, a comprehensive review of H2O2 production from g‐C3N4 modified by metal‐free strategies is still lacking. This review first recaps the mechanism of photocatalytic H2O2 production by g‐C3N4, including photoexcitation, carrier separation and redox reactions. Then, the perspective advances in metal‐free modified g‐C3N4 photocatalysts are presented, with the special focus on the kernel connection between different strategies and mechanism based on the pivotal stages of H2O2 production. Subsequently, recent applications of g‐C3N4‐based photocatalysts for in situ generated H2O2, mainly including water purification and organic synthesis, are briefly discussed. Finally, the prospects of g‐C3N4‐based photocatalysts are envisioned with the hope that it will have “something to do” in the field of H2O2 production. [ABSTRACT FROM AUTHOR]

Objective: To prospectively study the value of cystatin C in diagnosis of acute kidney injury (AKI) in patients after cardiac surgery., Methods: A total of 132 patients undergoing cardiopulmonary bypass were enrolled in this prospectively study. From each patient, blood samples were collected everyday before and after operation to detect the serum creatinine (Scr) and cystatin C levels by enzymatic method and particle-enhanced turbidimetric immunoassay (PETIA), respectively, and the glomerular filtration rate (eGFR) was estimated using MDRD equation. AKI diagnosis was made according to the RIFLE criteria of the Acute Dialysis Quality Initiative (ADQI) (R: Scr increased by > or =50%; I: Scr increased by > or =100%; F: Scr increased by > or =200%; L: Loss of kidney function; E: End-stage renal disease). Another AKI diagnostic criterion was also adopted according to the levels of cystatin C increment, namely an increase by > or =50%, > or =100%, and > or =200%., Results: Twenty-nine patients (21.9%) developed AKI of varied severities, including 10 meeting the R-criteria, 12 the I-criteria, 7 the F-criteria, with the other 103 patients without AKI serving as the control group. Cystatin C of the 29 AKI patients was drastically increased in comparison with that of the control group (P<0.001). Significant linear correlation was found between cystatin C and Scr (r=0.732, P<0.001) and between [cystatin C]-1 and estimated GFR (R=0.803, P<0.001). By the two diagnostic criteria based on cystatin C and Scr levels, respectively, the median diagnostic time of AKI was 2 days (range 1-4 days) and 3 days (range 2-5 days) for R criteria (10 patients, P=0.014), 3.5 days (range 1-6 days) and 5 days (range 2-8 days) for I criteria (12 patients, P=0.008), and 5 days (range 3-7 days) and 6.5 days (range 4-9 days) for F criteria (7 patients, P=0.02), respectively. ROC analysis confirmed excellent accuracy of cystatin C in AKI diagnosis (AUC=0.992). With the cut-off value of cystatin C increment by > or =50%, the diagnostic sensitivity and specificity of AKI was 92% and 95%, respectively., Conclusion: Cystatin C can serve as a good indicator for AKI diagnosis to allow earlier detection of AKI than Scr-based diagnosis in patients after cardiac surgery.

Objective: To evaluate the clinical effects of treatment with oral sildenafil on severe pulmonary hypertension after cardiac surgery., Methods: From September 2002 to January 2005, oral sildenafil was added to the treatment regime in 27 cases of severe pulmonary hypertension after cardiac surgery. All these cases were given general treatments including intravenous prostaglandin E1 and inhalation of nitric oxide before the use of sildenafil, which did not show obvious effects on decreasing pulmonary pressure. Then a combined treatment [general treatment plus oral sildenafil (1-2 mg/kg, q8h; Pfizer Ltd)] was instituted. Pulmonary artery pressure, systolic pulmonary artery pressure/systolic systemic blood pressure (Pp/Ps) were measured before and every hour after adding sildenafil., Results: One hour after adding sildenafil, the patients' pulmonary artery pressure decreased remarkably (P < 0.01) with no adverse effects on systematic artery pressure. SO(2) and PaO(2) of all cases improved respectively (P < 0.05). One or two days later, the patients' hemodynamics were stable and some patients stopped inhaling nitric oxide and the dosage of prostaglandin E1 decreased. 25 cases stopped use of ventilator and were discharged safely. 2 cases died of multiple organ dysfunction., Conclusion: Sildenafil is a highly selective and effective pulmonary hypertension vasodilator, which can be given for the treatment of pulmonary hypertension after cardiac surgery.