ABSTRACT
Core-shell nanostructures are widely used, and their photoacoustic (PA) properties are important for applications. However, the relations between their structural parameters and the properties of the PA spectrum are indirect because most theoretical models have been reported for them in the time domain. In this study, we develop a complete model in the frequency domain to analyze the PA response of core-shell particles. As in the case of solid spheres, the core-shell particles have pronounced resonant modes. The PA mode varies with the thickness of the shell and the radius of the core. Under single-pulse irradiation, PA signals of gold-silica nanospheres obtained by our theory agreed with those of the theory in the time domain and experiments. Under multi-pulse irradiation, the magnitude of the PA signals peaked whether the repeated excitation itself or its harmonic was equal to the PA mode. The structure could thus be monitored by the PA signals. These findings enrich PA theory and may inspire new techniques for the noninvasive characterization of nanoparticles.
ABSTRACT
OBJECTIVES: We conducted a prospective clinical randomized single-blind placebo-controlled trial (ChiCTR-TRC-14004156) to observe the effect of XiangBin granules on the recovery of gastrointestinal function and levels of brain-gut peptide motilin (MTL); vasoactive intestinal peptide (VIP); growth hormone releasing peptide-ghrelin, GHRP-ghrelin, and corticotropin releasing hormone (CRH), after transabdominal gynecological surgery. STUDY DESIGN: Patients undergoing gynecologic abdominal surgery were randomly divided in a 2:1 ratio (according to the data of pre-trial which was a small sample randomized trial in gynecology inpatient) into two groups: the larger treatment group taking XiangBin granules, and the smaller placebo group taking Chinese herbal placebo. The aim was to observe anal exhaust time, time to defecation, and the change in level of brain-gut peptide. RESULT: A significantly shorter time to first postoperative anal exhaust was observed in the treatment group. In the placebo group, the MTL level on the first day after surgery was lower than the preoperative level (P<0.05). In both groups, the GHRP-ghrelin level on the first postoperative day was lower than the preoperative level (P<0.05). In the treatment group, the GHRP-ghrelin level of the third day after surgery was higher than the first day after surgery (P<0.05). The CRH level on the first postoperative day was lower in the treatment group compared to the placebo group (P<0.05). CONCLUSION: XiangBin granules can effectively promote the recovery of gastrointestinal function after surgery for gynecologic abdomen and promote GHRP-ghrelin and MTL recovery, and reduce the postoperative secretion of CRH.
