RESUMEN
Acoustic transducers with graphene film have high sensitivity and wide bandwidth of frequency response as receivers. However, they exist in transmitting mode with low radiation performance. We propose an effective approach to enhance radiation performance of the graphene acoustic transducer by embedding a coil in insulating layer, and investigate the characteristics of graphene acoustic transducers by experiments. A graphene acoustic transducer is designed and fabricated. The highest receiving sensitivity of the transducer is -30 dB. The output sound pressure level of the transducer is more than 3 dB on average in the range of 2 â¼ 16 kHz compared without a coil. And the sound pressure level increases by 6 dB on average in the range of 40 â¼ 45 kHz. These results demonstrate that the graphene transducer maintains high receiving performance, and also improves acoustic radiation performance, which greatly expands its application field.
RESUMEN
Sepsis is a systemic inflammatory response to infection and includes severe sepsis, septic shock and death. Platelet endothelial cell adhesion molecule-1 (PECAM-1) is one cell adhesion molecule expressed on platelets and leukocytes. It regulates platelet activation and mediates transendothelial migration of leukocytes, thus maintaining the integrity of the vasculature. There are some animal experiments associated with the protective role of PECAM-1 against septic shock. However few host genetic risk factors have been identified for sepsis severity and susceptibility to septic shock. A case-control study was conducted, which included 217 patients with sepsis and 90 control subjects recruited from our hospital. One single nucleotide polymorphisms (SNP) of PECAM-1 gene Leu125Val (C373G) was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Serum soluble PECAM-1 (sPECAM-1) levels were determined by enzyme-linked immunosorbent assay (ELISA). Our results showed that the CG and GG genotypes of SNP in Leu125Val of PECAM-1 (rs668: C>G) was significantly associated with increased susceptibility to septic shock compared with CC genotype in sepsis patients (CG genotype, OR: 2.493, 95% CI: 1.175~5.287, P = 0.016; GG genotype: OR: 3.328, 95% CI: 1.445~7.666, P = 0.004). The serum levels of sPECAM-1 in the sepsis patients (47.1 ± 17.5 ng/ml) were significantly higher than those in the healthy controls (61.3 ± 20.9 ng/ml, P<0.01). Among sepsis patients, the serum levels of sPECAM-1 were significantly higher in CG and GG genotype than in CC genotype. In septic shock patients, nonsurvivors (83.7 ± 12.6 ng/ml, n = 69) had a significantly higher serum sPECAM-1 level than the survivors (76.9 ± 12.7 ng/ml, n = 53) (P<0.01). In conclusion, PECAM-1 Leu125Val polymorphism and its sPECAM-1 levels are associated with sepsis severity and susceptibility to septic shock.