Optimized terahertz generation in BNA organic crystals with chirped Ti:sapphire laser pulses.

We report on the efficient generation of intense terahertz radiation from the organic crystal N-benzyl-2-methyl-4-nitroaniline pumped by chirped Ti:sapphire femtosecond laser pulses. The THz energy and spectrum as a function of the pump fluence and duration of the chirped laser pulses are studied systematically. For the appropriate positively chirped pump pulses, a significant boost in the THz generation efficiency by a factor of around 2.5 is achieved, and the enhancement of high-frequency components (>1 THz) shortens the THz pulse duration. Via complete characterization of THz properties and transmitted laser spectra, this nonlinear behavior is attributed to the extended effective interaction length for phase matching as a result of the self-phase modulation of the intense pump laser pulses. Numerical calculations well reproduce the experimental observation. Our results demonstrate a robust, efficient, strong-field (up to several MV/cm) THz source using the common sub-10 mJ and sub-100 fs Ti:sapphire laser systems without optical parametric amplifiers.

Optical steering of electron beam in laser plasma accelerators.

Using a Dazzler system and tilting a compressor grating, we provide an effective way of using the laser group delay dispersion to continuously steer the electron beam accelerated by an asymmetric laser wakefield. The deviation angle of the electron beam was the same as that of the angularly chirped laser pulse from its initial optical axis, which is determined by the laser pulse-front-tilt (PFT). This method can be utilized to continuously control over the pointing direction of electron bunches to the requisite trajectories, especially for practical applications in highly sensitive alignment devices such as electron-positron colliders or undulators. Additionally, we investigate the effect of PFT on the properties of the electron beam.

Short-period high-strength helical undulator by laser-driven bifilar capacitor coil.

Laser wakefield accelerators have emerged as a promising candidate for compact synchrotron radiation and even x-ray free electron lasers. Today, to make the electrons emit electromagnetic radiation, the trajectories of laser wakefield accelerated electrons are deflected by transverse wakefield, counter-propagating laser field or external permanent magnet insertion device. Here, we propose a novel type of undulator that has a period of a few hundred microns and a magnetic field of tens of Tesla. The undulator consists of a bifilar capacitor-coil target that sustains a strong discharge current that generates a helical magnetic field around the coil axis when irradiated by a high-energy laser. Coupling this undulator with state-of-the-art laser wakefield accelerators can, simultaneously, produce ultra-bright quasi-monochromatic x-rays with tunable energy ranging 5-250 keV and optimize the free electron laser parameter and gain length compared with a permanent magnet-based undulator. This concept may pave a path toward ultra-compact synchrotron radiation and even x-ray free electron lasers.

Highly efficient generation of 0.2 mJ terahertz pulses in lithium niobate at room temperature with sub-50 fs chirped Ti:sapphire laser pulses.

We demonstrate generation of 0.2 mJ terahertz (THz) pulses in lithium niobate driven by Ti:sapphire laser pulses at room temperature. Employing tilted pulse front technique, the 800 nm-to-THz energy conversion efficiency has been optimized to 0.3% through chirping the sub-50 fs pump laser pulses to overcome multi-photon absorption and to extend effective interaction length for phase matching. Our approach paves the way for mJ-level THz generation via optical rectification using existing Ti:sapphire laser systems which can deliver Joule-level pulse energy with sub-50 fs pulse duration.

[L-carnitine improves sperm acrosin activity in male infertility patients].

OBJECTIVE: To evaluate the effect of L-carnitine (LC) on low sperm acrosin activity in infertile man. METHODS: A total of 240 male infertility patients with low sperm acrosin activity were randomly assigned to an LC group (n = 180) and a control group (n = 60) to be treated with LC (1g, tid) and vitamin E (VE) capsules (100 mg, tid) respectively, both for 3 months. Based on the results of routine semen analysis, the patients in the experimental group were further divided into oligozoospermia, asthenozoospermia and normozoospermia subgroups. Semen parameters and sperm acrosin activity were examined before and after treatment. RESULTS: Totally, 220 of the patients completed the treatment and follow-up, 163 in the LC medication and 57 in the VE control group. Compared with the baseline, the percentage of progressively motile sperm (PMS) was significantly increased in the LC group after 3 months of treatment (ï¼»32.58 ± 1.13ï¼½% vs ï¼»36.35 ± 1.26ï¼½%, P < 0.05), and so was sperm acrosin activity (ï¼»37.05±0.66ï¼½ vs ï¼»58.61±1.93ï¼½ µIU/106 sperm, P < 0.01). Sperm concentration, PMS and sperm acrosin activity were also improved in the VE control group after treatment, but with no statistically significant difference (P > 0.05). In comparison with pretreatment, remarkable increases were observed after LC medication in sperm concentration in the oligozoospermia subgroup (ï¼»11.27 ± 0.73ï¼½ vs ï¼»21.82 ± 4.21ï¼½ ×106/ml, P < 0.01) and PMS in the asthenozoospermia patients (ï¼»20.61 ± 0.85ï¼½% vs ï¼»29.81 ± 1.88ï¼½%, P < 0.01). And sperm acrosin activity was even higher after treatment in the asthenozoospermia than in the oligozoospermia and normozoospermia subgroups (ï¼»60.85 ± 3.04ï¼½ vs ï¼»56.32 ± 2.86ï¼½ and ï¼»57.09 ± 6.31ï¼½ µIU/106 sperm, P < 0.05). CONCLUSIONS: L-carnitine can effectively elevate sperm acrosin activity in male infertility patients, particularly in those with asthenozoospermia.

[Mechanism of Shikonin on spinal cord injury in rats based on TNFR/RIPK1 pathway].

OBJECTIVE: To explore the effect of shikonin on the recovery of nerve function after acute spinal cord injury(SCI) in rats. METHODS: 96 male Sprague-Dawley(SD)rats were divided into 4 groups randomly:sham operation group (Group A), sham operation+shikonin group (Group B), SCI+ DMSO(Group C), SCI+shikonin group (Group D).The acute SCI model of rats was made by clamp method in groups C and D . After subdural catheterization, no drug was given in group A. rats in groups B and D were injected with 100 mg·kg-1 of shikonin through catheter 30 min after modeling, and rats in group C were given with the same amount of DMSO, once a day until the time point of collection tissue. Basso-Beattie-Bresnahan(BBB) scores were performed on 8 rats in each group at 6, 12, and 3 d after moneling, and oblique plate tests were performed on 1, 3, 7 and 14 d after modeling, and then spinal cord tissues were collected. Eight rats were intraperitoneally injected with propidine iodide(PI) 1 h before sacrificed to detection PI positive cells at 24 h in each group. Eight rats were sacrificed in each group at 24 h after modeling, the spinal cord injury was observed by HE staining.The Nissl staining was used to observe survivor number of nerve cells. Western-blot technique was used to detect the expression levels of Bcl-2 protein and apoptosis related protein RIPK1. RESULTS: After modeling, BBB scores were normal in group A and B, but in group C and D were significantly higher than those in group A and B. And the scores in group D were higher than those in group C in each time point (P<0.05). At 12 h after modeling, the PI red stained cells in group D were significantly reduced compared with that in group C, and the disintegration of neurons was alleviated(P<0.05). HE and Nissl staining showed nerve cells with normal morphology in group A and B at 24h after operation. The degree of SCI and the number of neuronal survival in group D were better than those in group C, the difference was statistically significant at 24h (P<0.05). The expression of Bcl-2 and RIPK1 proteins was very low in group A and B;The expression of RIPK1 was significantly increased in Group C and decreased in Group D, with a statistically significant difference (P<0.05);The expression of Bcl-2 protein in group D was significantly higher than that in group C (P<0.05). CONCLUSION: Shikonin can alleviate the pathological changes after acute SCI in rats, improve the behavioral score, and promote the recovery of spinal nerve function. The specific mechanism may be related to the inhibition of TNFR/RIPK1 signaling pathway mediated necrotic apoptosis.

Balloon-Occluded Esophageal Variceal Obliteration Procedure: A Novel Technique Report from Three Centers.

Introduction: Esophageal variceal bleeding (EVB) is a potentially fatal complication of cirrhosis. The purpose of the present study was to evaluate the safety and efficacy of a novel technique of balloon-occluded esophageal varices (EVs) obliteration (BEVO) for EVs classified as F2 (medium size, F2-EVs) and F3 (large size, F3-EVs). Materials and Methods: Between December 2020 and December 2021, a total of 73 consecutive patients with EVs were treated using BEVO. An injection of sclerosant was administered via direct puncture of the varices during balloon occlusion. Immediate postprocedural Doppler endoscopic ultrasonography (EUS) was conducted to evaluate the blood flow in the EVs. Several factors, including the technical success, controlling of acute bleeding, intraoperative bleeding at the injection site, variceal eradication, variceal recurrence, and BEVO-related complications, were assessed. Results: BEVO was successfully performed in all patients. Immediate hemostasis was achieved in 100% (25/25) of patients with active EVB. The incidence of injection site intraoperative bleeding presenting as oozing and spurting bleeding was 76.71% (56/73) and 8.22% (6/73), respectively. Based on Doppler EUS and endoscopic examination, EVs were completely eradicated in 71 out of 73 patients (97.26%) after three sessions. A total of 3 (4.11%) patients were diagnosed with EV recurrence during follow-up after complete EV eradication. Retrosternal chest discomfort (13.70%; 10/73) and abdominal bloating (2.74%; 2/73) were spontaneously relieved after a few days. No serious BEVO-related complications were observed. Discussion: BEVO is a convenient and effective treatment for obliterating F2 and F3 EVs. Clinical Trial Registration No. ChiCTR2000039974.

Comparison of Clinical Effects of the Modified Masquelet Technique and Kirschner Wire External Fixation-Assisted Autogenous Bone Transplantation in the Treatment of Segmental Metacarpophalangeal Bone Defects.

OBJECTIVE: The present study aims to explore the (1) clinical effects of the modified Masquelet technique, whose improved Masquelet technique innovates the in vitro plasticity of the bone cement module and prefabricated hollow design, and the Kirschner wire external fixation-assisted autologous bone transplantation technique in the treatment of segmental metacarpophalangeal bone defects and (2) the differences between the two techniques. METHODS: The clinical data of 32 patients with segmental metacarpophalangeal bone defects (15 patients treated with the modified Masquelet technique and 17 patients treated with the self-made Kirschner wire external fixation technique) admitted to our department between January 2012 and January 2020 were retrospectively analyzed. The postoperative bone healing time, hand function, and complications were compared between the two groups. RESULTS: The two groups were comparable; there were no significant differences in age, sex, length of bone defect, and time from injury to operation between the two groups (P > 0.05). All patients were followed up with for 6-24 months (average = 13.7 months), and all patients with segmental metacarpophalangeal bone defects achieved fracture healing. The postoperative hospital stay, fracture healing time, functionary scores of the affected limb, and incidence of severe complications were better in the modified group than in the external fixation group (P < 0.05). CONCLUSION: Compared with the Kirschner wire external fixation stent assisted autologous bone transplantation, the improved Masquelet technique has the advantages of simple operation, fast healing, accurate effect, wide indications, and less complications, making it more worthy of clinical promotion.

Factors affecting failed trial of labor and countermeasures: A retrospective analysis.

BACKGROUND: Vaginal delivery is the ideal mode of delivery for the termination of a pregnancy. However, the cesarean section rate in China is much higher than the published by the World Health Organization in the Lancet in 2010. AIM: To retrospectively analyze the factors related to failed trial of labor and the clinical indications for cesarean section conversion, explore how to promote the trial of labor success rate, and determine the feasibility of reducing the rate of conversion to cesarean section. METHODS: A retrospective analysis was performed on 9240 maternal women who met vaginal delivery conditions and required a trial of labor from January 2016 to December 2018 at our hospital. Among them, 8164 pregnant women who had a successful trial of labor were used as a control group, and 1076 pregnant women who had a failed trial of labor and converted to an emergency cesarean section were used as an observation group. The patients' clinical data during hospitalization were collected for comparative analysis, the related factors of the failed trial of labor were discussed, and reasonable prevention and resolution strategies were proposed to increase the success rate of trial of labor. RESULTS: The analysis revealed that advanced age (≥ 35 years old), macrosomia (≥ 4000 g), delayed pregnancy (≥ 41 wk), use of uterine contraction drugs, primipara, and fever during labor were associated with conversion to an emergency cesarean section in the failed trial of labor. Multivariate regression analysis showed that age, gestational age, primipara, use of uterine contraction drugs, fever during birth, and newborn weight led to a higher probability of conversion to an emergency cesarean section in the failed trial of labor. The analysis indicated that the following clinical indications were associated with the conversion to cesarean section in the failed trial of labor: Fetal distress (44.3%), social factors (12.8%), malpresentation (face presentation, persistent occipitoposterior position, and persistent occipitotransverse position) (9.4%), and cephalopelvic disproportion (8.9%). CONCLUSION: The conversion to emergency cesarean section in failed trial of labor is affected by many factors. Medical staff should take appropriate preventive measures for the main factors, increase the trial of labor success rate, improve the quality of delivery, ensure the safety of mother and child during the perinatal period, and improve the relationship between doctors and patients.

Esophageal Scab Mimicking a Parasite: A Case Report.

BACKGROUND Parasitic helminths in the esophagus are rare. Here, we report a case of esophageal scab mimicking a parasite. CASE REPORT A 65-year-old man was admitted to our hospital because after choking on food. Gastroscopy showed 2 foreign bodies adherent to the esophagus wall 28 and 34 cm from the incisor, which appeared to be a fluke. Two fluke-like foreign bodies (1.5 and 1.8 cm in length) were removed from the esophageal ulcer with forceps. After fixation with alcohol, the suspected fluke-like foreign bodies were noted to be brown and woody. Under a light microscope, the structure of the foreign body was not apparent, and no typical flatworm tegument structure was demonstrated on pathologic sections, but it had a blood clot-like structure. Administration of albendazole did not expel any helminths. A stool examination showed no eggs of the putative flukes. The genomic DNA of the suspected flukes was extracted and a 700 bp fragment was amplified by universal barcoding primers. The sequencing showed that the homology with human cytochrome c oxidase subunit I gene was 98.8%. CONCLUSIONS The scab formed by the esophageal ulcer was identified based on clinical manifestations, anti-helminth and stool examinations, parasite morphology, and molecular biology. Our experience with this case suggests that the universal barcoding technique can be used for identification of foreign bodies suspected to be parasites.

Highly sensitive and selective detection of human carboxylesterase 1 activity by liquid chromatography with fluorescence detection.

Human carboxylesterases 1 (hCE1), one of the most important human drug metabolizing enzymes, catalyzes the hydrolysis of a large number of structurally diverse of endogenous and exogenous substrates. However, a practical, reliable and sensitive method for the precise measurement of hCE1 activities in complex biological samples has been rarely reported. In this study, a liquid chromatography-fluorescence detection (LC-FD) based method was developed for highly selective and sensitive measurement of hCE1 activities in human tissue and cell preparations. This method was based on the fluorimetric detection of HMBT, the hydrolyzed product of BMBT which was a newly developed specific probe substrate for hCE1. The developed LC-FD method was fully validated in terms of specificity, sensitivity, linearity, precision, recovery and stability. With the help of LC separation, most polar endogenous compounds in biological samples could be eluted in the column dead time, which is very beneficial for accurate determination of hCE1 activities in complex biological samples. The lower limit of quantification for HMBT (product of hCE1) of this LC-FD based method was as low as 20nM, which was quite lower than other reported methods. The method also exhibited good precision, both intra- and inter- assay variances were both lower than 2.5%. Furthermore, the newly developed method was successfully applied to measure hCE1 activity in human liver preparations from individual donors (n=12), as well as in homogenates from eleven different human cell lines. All these findings combined with this practical method are very helpful for the deep understanding of the expression and function of hCE1 in human biological samples.

Effect of intravariceal sclerotherapy combined with esophageal mucosal sclerotherapy using small-volume sclerosant for cirrhotic patients with high variceal pressure.

AIM: To explore the effect of intravariceal-mucosal sclerotherapy using small dose of sclerosant on the recurrence of esophageal varices. METHODS: We randomly assigned 38 cirrhotic patients with previous variceal bleeding and high variceal pressure (> 15.2 mmHg) to receive endoscopic variceal ligation (EVL) and combined intravariceal and esophageal mucosal sclerotherapy (combined group) using small-volume sclerosant. The end-points of the study were rebleeding and recurrence of esophageal varices. RESULTS: During a median follow-up period of 16 mo, varices recurred in 1 patient in the combined group as compared with 7 patients in the EVL group (P = 0.045). Rebleeding occurred in 3 patients in the EVL group as compared with 1 patient in the combined group (P = 0.687). No patient died in the two groups. No significant differences were observed between the two groups with respect to serious adverse events. CONCLUSION: Intravariceal-mucosal sclerotherapy using small dose of sclerosant is more effective than EVL in decreasing the incidence of variceal recurrence for cirrhotic patients.

ß-2 Adrenergic receptor gene polymorphism and response to propranolol in cirrhosis.

AIM: To evaluate the association of ß-2 adrenergic receptor (ß2-AR) gene polymorphism with response of variceal pressure to propranolol in cirrhosis. METHODS: Sixty-four non-related cirrhotic patients participated in this study and accepted variceal pressure measurement before and after propranolol administration. Polymorphism of the ß2-AR gene was determined by directly sequencing of the polymerase chain reaction products from the DNA samples that were prepared from the patients. RESULTS: The prevalence of Gly16-Glu/Gln27 and Arg16-Gln27 homozygotes, and compound heterozygotes was 29.7%, 10.9%, and 59.4%, respectively. Patients with cirrhosis with Gly16-Glu/Gln27 homozygotes had a greater decrease of variceal pressure after propranolol administration than those with Arg16-Gln27 homozygotes or with compound heterozygotes (22.4% ± 2.1%, 13.1% ± 2.7% and 12.5% ± 3.1%, respectively, P < 0.01). CONCLUSION: The variceal pressure response to propranolol was associated with polymorphism of ß2-AR gene. Patients with the Gly(16)-Glu/Gln(27) homozygotes probably benefit from propranolol therapy.

Quasi-steady-state air plasma channel produced by a femtosecond laser pulse sequence.

A long air plasma channel can be formed by filamentation of intense femtosecond laser pulses. However, the lifetime of the plasma channel produced by a single femtosecond laser pulse is too short (only a few nanoseconds) for many potential applications based on the conductivity of the plasma channel. Therefore, prolonging the lifetime of the plasma channel is one of the key challenges in the research of femtosecond laser filamentation. In this study, a unique femtosecond laser source was developed to produce a high-quality femtosecond laser pulse sequence with an interval of 2.9 ns and a uniformly distributed single-pulse energy. The metre scale quasi-steady-state plasma channel with a 60-80 ns lifetime was formed by such pulse sequences in air. The simulation study for filamentation of dual femtosecond pulses indicated that the plasma channel left by the previous pulse was weakly affected the filamentation of the next pulse in sequence under our experimental conditions.