The CFTR polymorphisms poly-T, TG-repeats and M470V in Chinese males with congenital bilateral absence of the vas deferens

Congenital bilateral absence of the vas deferens （CBAVD） is a frequent cause of obstructive azoospermia, and mutations of the cystic fibrosis transmembrane conductance regulator （CFTR） gene have also been frequently identified in patients with CBAVD. However, the distribution of the CFTR polymorphisms M470V, poly-T, TG-repeats and F508del mutation in the Chinese CBAVD population with presumed low cystic fibrosis （CF） frequency remains to be evaluated. Samples obtained from 109 Chinese infertile males with CBAVD and 104 normal controls were analyzed for the presence of CFTR （TG）m（T）n, M470V and F508del by PCR amplification followed by direct sequencing. Our study showed that the F5OSdel mutation was not found in our patients. The 5T mutation was present with high frequency in Chinese CBAVD patients and IVS8-5T linked to either 12 or 13 TG repeats was highly prevalent among CBAVD patients （97.22% of 72 cases and 96.91% of 97 alleles with IVS8-5T）. Moreover, a statistically significant relationship between TG 12-5T-V470 haplotype and CBAVD was detected. This study indicated that the CFTR polymorphisms poly-T, TG-repeats and M470V might affect the process of CBAVD in the Chinese population.

Simulation and photoelectron track reconstruction of soft X-ray polarimeter

The soft X-ray polarimeter(SXP)is a detector with a wide energy range,large area,and large field of view.A SXP will be mounted on the Chinese Space Station and will mainly focus on detecting the polarization of transient soft X-ray(2–10 keV)sources,especially gamma-ray bursts(GRBs).In this work,a polarimeter detector unit is taken as an example,and Geant4 and Garfield++software are used to simulate the detection efficiency and track production.An improved track reconstruction algorithm is proposed and used to reconstruct two-dimensional images of the tracks.In this method,the initial emission angle of photoelectrons is reconstructed from the initial part of the track by shortening or extending the initial part of the track until the remaining track is straight,and the number of pixels is within an adjustable threshold.The modulation factor of the photoelectronic tracks after reconstruction reaches approximately 57%in the photon energy range of 7–10 keV.

Reference limits： limited references in laboratories worldwide

Dear Editor, The newly revised World Health Organization （WHO） semen analysis manual provides the lower reference limits of semen parameters based on ＂the raw data from between about 400 and 1 900 semen samples, from recent fathers in eight countries on three continents＂： Australia, Europe and North America .

Surface quality investigation in high-speed dry milling of Ti-6Al-4V by using 2D ultrasonic-vibration-assisted milling platform

Ultrasonic-vibration-assisted milling(UVAM)is an advanced method for the efficient and precise machining of difficult-to-machine materials in modern manufacturing.However,the milling efficiency is limited because the ultrasonic vibration toolholder ER16 collet has a critical cutting speed.Thus,a 2D UVAM platform is built to ensure precision machining efficiency and improve the surface quality without changing the milling toolholder.To evaluate this 2D UVAM platform,ultrasonic-vibration-assisted high-speed dry milling(UVAHSDM)is performed to process a titanium alloy(Ti-6Al-4V)on the platform,and the milling temperature,surface roughness,and residual stresses are selected as the important indicators for performance analysis.The results show that the intermittent cutting mechanism of UVAHSDM combined with the specific spindle speed,feed speed,and vibration amplitude can reduce the milling temperature and improve the texture of the machined surface.Compared with conventional milling,UVAHSDM reduces surface roughness and peak-groove surface profile values and extends the range of residual surface compressive stresses from−413.96 MPa to−600.18 MPa.The excellent processing performance demonstrates the feasibility and validity of applying this 2D UVAM platform for investigating surface quality achieved under UVAHSDM.

Analysis of risk factors for lateral lymph node metastasis in papillary thyroid carcinoma: A retrospective cohort study

Objective: To investigate the risk factors for lateral lymph node metastasis (LLNM) in papillary thyroid carcinoma (PTC).Methods: A retrospective analysis of 209 patients with PTC who underwent primary surgery at the Beijing Friendship Hospital affiliated with Capital Medical University from November 2014 to November 2018 was performed. The patients were divided into the LLNM group and the non-LLNM group. The clinical and pathological characteristics of the patients were analysed. The risk factors for LLNM were analysed by univariate and multivariate analyses.Results: The incidence of LLNM was 13.4% in PTC patients. Univariate analysis showed that the maximum diameter of the primary tumour > 2 cm (P < 0.001), bilateral primary tumour (P= 0.020), extrathyroidal extension (ETE) (P < 0.001), central lymph node metastasis (CLNM) (P < 0.001), and CLNM number ≥ 5 (P < 0.001) were significantly associated with LLNM. Multivariate logistic regression analysis showed that the maximum diameter of the primary tumour > 2 cm, ETE, and CLNM were independent risk factors for LLNM (OR values were 3.880, 5.202, and 4.474, respectively). There were 6 patients with skip lateral cervical lymph node metastasis, accounting for 21% of all LLNM patients.Conclusion: This study revealed several independent risk factors for predicting LLNM in PTC patients, such as the maximum diameter of the primary tumour > 2 cm, ETE and CLNM. Lateral neck dissection may be recommended in PTC patients with those risk factors. Paying attention to the occurrence of skip lateral cervical lymph node metastasis during the clinical diagnosis and treatment processes is necessary.