In the cultural stone heritage,progressive deteriorations develop over time with the effect of atmospheric processes.These deteriorations can reach to a significant degree that threaten the integrity of the monuments ...In the cultural stone heritage,progressive deteriorations develop over time with the effect of atmospheric processes.These deteriorations can reach to a significant degree that threaten the integrity of the monuments built from weak-strength rocks.In this study,it is aimed to determine the deteriorations caused by atmospheric processes on the monument surface in cultural heritage works built by carving into low-strength pyroclastic rocks by nondestructive tests(NDTs).To this end,two historic structures in the Kilistra Ancient City of Konya(Turkey)were selected.The index,strength,mineralogical and petrographic properties of the rocks,in which the monuments were carved,were first investigated.Then,contour scaling,crack,efflorescence and biodeterioration types were determined on the facades of the monuments.Later,NDT deterioration change maps were prepared based on the data obtained by performing the relative humidity,Schmidt hammer rebound(SHR),and P-wave velocity(Vp)measurements on the facades of the monuments.In the deterioration maps,it was determined that the SHR and Vp values of the rock were low in the capillary,infiltration,and crack zones with water penetration in the monuments built on low-strength pyroclastic rocks.However,deterioration was less in the regions with more limited water access according to zones.展开更多
The mechanism of idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) is not clear. Many clinical reports have suggested a mechanism of triggered activity. However, there are ...The mechanism of idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) is not clear. Many clinical reports have suggested a mechanism of triggered activity. However, there are few studies investigating this because of the technical difficulties associated with examining this theory. The L-type calcium current (ICa-L), an important inward current of the action potential (AP), plays an important role in arrhythmogenesis. The aim of this study was to explore differences in the APs of right ventricular (RV) and RVOT cardiomyocytes, and differences in electrophysiological characteristics of the ICa-L in these myocytes. Rabbit RVOT and RV myocytes were isolated and their AP and ICa-L were investigated using the patch-clamp technique. RVOT cardiomyocytes had a wider range of AP duration (APD) than RV cardiomyocytes, with some markedly prolonged APDs and markedly shortened APDs. The markedly shortened APDs in RVOT myocytes were abolished by treatment with 4-AP, an inhibitor of the transient outward potassium current, but the markedly prolonged APDs remained, with some myocytes with a long AP plateau not repolarizing to resting potential. In addition, early afterdepolarization (EAD) and second plateau responses were seen in RVOT myocytes but not in RV myocytes. RVOT myocytes had a higher current density for ICa-L than RV myocytes (RVOT (13.16±0.87) pA pF-1, RV (8.59±1.97) pA pF-1; P<0.05). The ICa-L and the prolonged APD were reduced, and the EAD and second plateau response disappeared, after treatment with nifedipine (10 μmol L-1), which blocks the ICa-L. In conclusion, there was a wider range of APDs in RVOT myocytes than in RV myocytes, which is one of the basic factors involved in arrhythmogenesis. The higher current density for ICa-L is one of the factors causing prolongation of the APD in RVOT myocytes. The combination of EAD with prolonged APD may be one of the mechanisms of RVOT-VT generation.展开更多
基金the grants from Scientific Research Foundation of Adıyaman University MU¨FYL/2017-0001.
文摘In the cultural stone heritage,progressive deteriorations develop over time with the effect of atmospheric processes.These deteriorations can reach to a significant degree that threaten the integrity of the monuments built from weak-strength rocks.In this study,it is aimed to determine the deteriorations caused by atmospheric processes on the monument surface in cultural heritage works built by carving into low-strength pyroclastic rocks by nondestructive tests(NDTs).To this end,two historic structures in the Kilistra Ancient City of Konya(Turkey)were selected.The index,strength,mineralogical and petrographic properties of the rocks,in which the monuments were carved,were first investigated.Then,contour scaling,crack,efflorescence and biodeterioration types were determined on the facades of the monuments.Later,NDT deterioration change maps were prepared based on the data obtained by performing the relative humidity,Schmidt hammer rebound(SHR),and P-wave velocity(Vp)measurements on the facades of the monuments.In the deterioration maps,it was determined that the SHR and Vp values of the rock were low in the capillary,infiltration,and crack zones with water penetration in the monuments built on low-strength pyroclastic rocks.However,deterioration was less in the regions with more limited water access according to zones.
文摘The mechanism of idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) is not clear. Many clinical reports have suggested a mechanism of triggered activity. However, there are few studies investigating this because of the technical difficulties associated with examining this theory. The L-type calcium current (ICa-L), an important inward current of the action potential (AP), plays an important role in arrhythmogenesis. The aim of this study was to explore differences in the APs of right ventricular (RV) and RVOT cardiomyocytes, and differences in electrophysiological characteristics of the ICa-L in these myocytes. Rabbit RVOT and RV myocytes were isolated and their AP and ICa-L were investigated using the patch-clamp technique. RVOT cardiomyocytes had a wider range of AP duration (APD) than RV cardiomyocytes, with some markedly prolonged APDs and markedly shortened APDs. The markedly shortened APDs in RVOT myocytes were abolished by treatment with 4-AP, an inhibitor of the transient outward potassium current, but the markedly prolonged APDs remained, with some myocytes with a long AP plateau not repolarizing to resting potential. In addition, early afterdepolarization (EAD) and second plateau responses were seen in RVOT myocytes but not in RV myocytes. RVOT myocytes had a higher current density for ICa-L than RV myocytes (RVOT (13.16±0.87) pA pF-1, RV (8.59±1.97) pA pF-1; P<0.05). The ICa-L and the prolonged APD were reduced, and the EAD and second plateau response disappeared, after treatment with nifedipine (10 μmol L-1), which blocks the ICa-L. In conclusion, there was a wider range of APDs in RVOT myocytes than in RV myocytes, which is one of the basic factors involved in arrhythmogenesis. The higher current density for ICa-L is one of the factors causing prolongation of the APD in RVOT myocytes. The combination of EAD with prolonged APD may be one of the mechanisms of RVOT-VT generation.
