Nonlinear error correction for Terahertz FMCW System by a new beat frequency estimation method.

Terahertz (THz) frequency modulated continuous wave (FMCW) technology is a means of nondestructive testing. The signal's nonlinearity is an unavoidable problem in the daily application of THz FMCW technology. The signal's nonlinearity will lead to the spectrum broadening of the FMCW's beat frequency (BF) signal, which degrades the range resolution and result in distance-measuring error. Traditional methods require additional hardware or require a lot of computation, which are not conducive to the miniaturization of the system and real-time measurement. A novel method for correcting the nonlinear error of THz FMCW technology has been proposed and demonstrated in this article. In the proposed method, the windowed Fourier transform (WFT) is introduced to estimate the BF corresponding to the measured target, according to the linearity distribution of voltage-controlled oscillator (VCO). In this way, the measured target's BF can be accurately estimated from the unprocessed BF signal with a poor linearity. From the estimated BF of the reference target, the non-linear compensation coefficients are calculated. With the non-linear compensation coefficients, the non-linearity of the output BF signal can be calibrated. The results of simulations and experiments show that the proposed method allows the range resolution of an FMCW system to reach the theoretical limit.

[Application of high performance liquid-ion trap mass spectrometry in analyzing saponins in sodium aescinate].

Sodium aescinate, which is produced from saponins of Chinese Buckeye Seed, is a prescription drug for treatment of brain edema and all kinds of swellings caused by surgery. In this article, high-performance liquid chromatography/ion trap (HPLC-IT) mass spectrometry was applied to study the characteristic ions of ten reference substances, namely escin Ⅰa, escin Ⅰb, isoescin Ⅰa, isoescin Ⅰb, aesculiside A, aesculiside B, aesculuside A, escin Ⅳc, escinⅡa and escin Ⅴ, which were isolated from aescinate. Furthermore, 19 saponin compounds were predicted in sodium aescinate, besides the above mentioned reference substances. The study showed that sapogenins in sodium aescinate had two structural types, namely protoaescigenin and barringenol C, and the substituent acetyl, tigloyl or angeloyl was usually located at C-21, C-22 or C-28 position. Among these predicted saponins, their sugar chains were all located at C-3 position consisting of glucose and glucuronide. This study provides experimental data for chemical constituents in sodium aescinate and scientific basis for quality and safety evaluation.

[Salidroside inhibits hypoxia-induced phenotypic modulation of corpus cavernosum smooth muscle cells in vitro].

OBJECTIVE: To explore the effects of salidroside on the phenotypic modulation of corpus cavernosum smooth muscle cells (CCSMC) in hypoxic SD rats. METHODS: CCSMCs were cultured in vitro and identified by immunohistochemistry. The cells were divided into six groups: normal control (21% O2), hypoxia (1% O2), hypoxia + salidroside 1 mg/L, hypoxia + salidroside 3 mg/L, hypoxia + salidroside 5 mg/L and hypoxia + PGE1 0.4 microg/L, and then cultured for 48 hours. The relative expressions of alpha-actin and osteopontin (OPN) in each group were determined by RT-PCR. RESULTS: The in vitro cultured CCSMCs grew well, with anti-alpha-smooth muscle actin monoclonal antibodies immunohistochemically positive. The relative expression of alpha-actin was markedly decreased while that of OPN remarkably increased in the hypoxia group as compared with the normal control group (P < 0.01). The hypoxia + salidroside 5 mg/L group showed a significantly higher expression of alpha-actin and lower expression of OPN than the hypoxia group (P < 0.01), but exhibited no significant differences from the hypoxia + PGE group (P > 0.05). CONCLUSION: Hypoxia can reduce the relative expression level of alpha-actin and increase that of OPN in the CCSMCs of SD rats, namely, induce their phenotypic modulation from the contraction to the non-contraction type. Salidroside can restrain hypoxia-induced phenotypic modulation of CCSMCs, and its inhibitory effect at 5 mg/L is similar to that of PGE1.

[Hypoxia induces fibrosis of corpus cavernosum smooth muscle in SD rats].

OBJECTIVE: To explore the effect of hypoxia on the fibrosis of corpus cavernosum smooth muscle cells (CCSMC) in SD rats. METHODS: CCSMCs were cultured in vitro, identified by immunohistochemistry, and then exposed to hypoxia at the concentration of 1% O2 for 12, 24, 48 and 72 hours. Those exposed to normal oxygen concentration for the corresponding lengths of time were used as the control. The relative expressions of TGF-131, type I collagen and type DI collagen were determined by RT-PCR. RESULTS: The in vitro cultured CCSMCs grew well, and the anti-a-smooth muscle actin monoclonal antibodies were positive on immunohistochemical staining. The relative expression levels of TGF-beta1, type I collagen and type mI collagen were positively correlated with the time of hypoxia interference within 48 hours, and did not increase further with prolonged exposure. CONCLUSION: When exposed to hypoxia, the relative expressions of TGF-beta1, type I collagen and type mI collagen in the CCSMCs of SD rats increased with the length of time, and reached the peak at 48 hours. Hypoxia can cause fibrosis of CCSMCs in SD rats.

Consecutive nightly measurements are needed for accurate evaluation of nocturnal erectile capacity when the first-night laboratory recording is abnormal.

Multiple measurements of nocturnal penile tumescence and rigidity (NPTR) are widely accepted as a method to differentiate psychogenic erectile dysfunction (ED) from organic ED. However, direct evidence remains limited regarding the first-night effect on NPTR measurement using the RigiScan. Here, we evaluated the first-night effect on the results of NPTR measurement to validate the necessity of NPTR measurement for two consecutive nights, particularly when abnormal first-night measurements are recorded in a laboratory setting. We retrospectively reviewed 105 patients with a complaint of ED, who underwent NPTR measurement using the RigiScan in the Department of Infertility and Sexual Medicine, the Third Affiliated Hospital of Sun Yat-sen University (Guangzhou, China), for two consecutive nights, during the period from November 2015 to May 2016. NPTR parameters were collected and analyzed. We found that more effective nocturnal erections were detected during the second night than during the first night (P <0.001). Twenty percent of all patients had no effective erection during the first night, but exhibited at least one effective erection during the second night. The negative predictive value of NPTR measurement during the first night was 43.2%; this was significantly lower than that on the second night (84.2%; P = 0.003). Most NPTR parameters were better on the second night than on the first night. The first-night effect might be greater among patients younger than 40 years of age. In conclusion, two consecutive nightly measurements of NPTR can avoid a false-abnormal result caused by the first-night effect; moreover, these measurements more accurately reflect erectile capacity, especially when the first-night record is abnormal in a laboratory setting.

Triterpenoid Saponins from the Seeds of Aesculus chinensis and Their Cytotoxicities.

Six new triterpenoid saponins, aesculusosides A-F (1-6), together with 19 known ones, were isolated from the seeds of Aesculus chinensis. The new structures were elucidated through extensive spectroscopic analyses and by comparison with previously reported data. Some of the isolates were evaluated for their cytotoxic activities against MCF-7 cell line by an MTT assay, and compounds 15, 16, 19, and 23-25 exhibited inhibitory activities against MCF-7 with IC50 values ranging from 7.1 to 31.3 µM.