Stoichiometry and stable isotopes of plants and their response to environmental factors in boreal peatland, Northeast China

The alterations of plant composition and diversity pose a threat to the stability of the carbon pool in boreal peatland under climate change. We collected the samples of three plant functional types (deciduous shrubs, evergreen shrubs, and sedge) in seven permafrost peatlands of the Great Hing’an Mountains, China, and measured the properties of total carbon (TC), nitrogen (TN), and phosphorus (TP), their stoichiometric ratios (C:N, C:P, and N:P), and the stable isotope values (δ13C and δ15N) of six tissues (ranging from leaves to roots). For TC, TN, and TP, the contents had an average of 470.69 ± 1.56, 8.03 ± 0.23, and 1.71 ± 0.61 mg·g−1, respectively. TC contents of sedge were lower than those of shrubs for the whole plant. The allocations of N and P to shrub leaves were higher than to stems and roots. There was a similar trend of TN and TP contents, and stoichiometric ratios from leaves to roots between deciduous shrubs and evergreen shrubs. Shrubs and sedge have similar C: N in leaves and fine roots, while leaves of sedge C:P and N:P ratios were higher than shrubs, mainly showed that sedge is N and P co-limitation and shrubs are N limitation. The values of δ13C and δ15N were significantly higher in leaves and roots of sedge than those of shrubs, which means shrubs have higher nutrient acquisition strategies. These results support the shrubs are expanding in the boreal peatland under climate warming through nutrient competition. TC contents of all deciduous shrubs and sedge tissues were positively linear correlated to MAT and the values of δ13C and δ15N in sedge had significant relationships with MAT and MAP. Our results imply warming can increase plant photosynthesis in boreal peatland, and sedge was more sensitive to climate change. These findings would be helpful to understanding the responses of different plant tissues to climate changes in permafrost peatland

PMMA Sandwiched Bi2Te3 Layer as a Saturable Absorber in Mode-Locked Fiber Laser

In this paper, we fabricated a PMMA sandwiched Bi2Te3 self-assembly layer as a saturable absorber device, which was used as a passive mode locker for ultrafast pulse generation at the telecommunication band. Nanosheets of Bi2Te3 as a bulk topological insulator were successfully synthesized through a solvothermal treatment and self-assemble method to form a thin film at a water-air interface. In order to transfer the Bi2Te3 self-assembly layer to the optical fiber end, we design a construction of two PMMA layers sandwiched self-assembly layer. By incorporating this saturable absorber into an erbium-doped fiber laser, femtosecond mode-locking operation was experimentally demonstrated. The output pulse width is about 505 fs. Our results indicate that PMMA sandwiched topological insulator layer structure could be an improvement technology in traditional PMMA transfer method and could be used as a long-term stable saturable absorber for the passively mode locking lasers

Second harmonic generation in two different arrangement of type I collagen on nonlinear microscopy

Second harmonic generation (SHG) microscopy has emerged as a powerful tool for biomedical research, especially in fibrosis-related disease studies. In this letter, two different arrangement models were established to compare SHG in type I collage, which is a major risk factor for fibrotic diseases. Different models result in distinct SHG intensity curves, which are functions of polarization angle. Based on those models, the influences of different scatters array and incident polarization on SHG in biological tissues were discussed. For practical application, this theoretical approach can guide us to judge the array pattern or the slice type of biological tissues and lead us to analyze the severity of collage diseases. Moreover, the relationship between the SHG intensity and parameter ρ was revealed, which is closely related to the age of living organisms. OCIS codes: (180.4315) Nonlinear microscopy, (190.1900) Diagnostic applications of nonlinear optic, (170.6930) Tissu

Numerical Simulations of Transfer of Spatial Beam Aberrations in Optical Parametric Chirped-Pulse Amplification

In this paper, the spatial characteristics of the optical parametric chirped-pulse amplification (OPCPA) process were numerically studied when initial pump beam was aberrated. Numerical results showed that the spatial walk-off effect transferred phase modulation partly to the signal beam as the pump phase was modulated. Moreover, the modulation amplitude became increasingly severe as the nonlinear length extended. In the absence of phase aberration in the initial input signal, the induced phase aberration in the output signal was assumed as the differential form of the pump beam phase. As the pump beam intensity was modulated, the spatial walk-off effect reduced the influence of pump beam noise on beam quality and the angular spectrum but reduced signal gain simultaneously; thus, it may do more harm than good in the OPCPA process. In the case of a non-diffraction-limited pump beam, the greater the beam quality factor Mp2, the lower the conversion efficiency of the output signal in the OPCPA process. These results have important guiding significance for optimized design of an OPCPA system for high power laser

Research on release rate of volatile organic compounds in typical vessel cabin

[Objectives] Volatile Organic Compounds (VOC) should be efficiently controlled in vessel cabins to ensure the crew's health and navigation safety. As an important parameter, research on release rate of VOCs in cabins is required. [Methods] This paper develops a method to investigate this parameter of a ship's cabin based on methods used in other closed indoor environments. A typical vessel cabin is sampled with Tenax TA tubes and analyzed by Automated Thermal Desorption-Gas Chromatography-Mass Spectrometry (ATD-GC/MS). The lumped mode is used and the release rate of Benzene, Toluene, Ethylbenzene and Xylene (BTEX), the typical representatives of VOCs, is obtained both in closed and ventilated conditions. [Results] The results show that the content of xylene and Total Volatile Organic Compounds (TVOC) exceed the indoor environment standards in ventilated conditions. The BTEX release rate is similar in both conditions except for the benzene. [Conclusions] This research builds a method to measure the release rate of VOCs, providing references for pollution character evaluation and ventilation and purification system design

Safety and efficacy of self-expandable metallic stent combined with 125I brachytherapy for the treatment of malignant obstructive jaundice

Abstract Background Several previous studies demonstrated that the combination of self-expandable metallic stents (SEMS) and 125I seed implantation might prolong stent patency and obtain survival benefits for malignant obstructive jaundice (MOJ) patients. However, these studies rarely mentioned a comparison between CT-guided intratumoral 125I seed implantation and intraluminal 125I seed strand insertion combined with stenting for the management of MOJ. This study aimed to further evaluate the safety and efficacy of SEMS combined with 125I brachytherapy in the management of unresectable MOJ. Methods Fifty-nine patients with unresectable MOJ were retrospectively included from March 2018 to June 2021. The main therapeutic outcomes were evaluated in terms of stent patency, and overall survival. Cumulative stent patency and overall survival rates were calculated by Kaplan–Meier survival analysis. Both clinical and treatment factors associated with survival were analyzed. Results Technical success was achieved in all patients. The clinical success rate was 94% (32/34) in the seeds group and 92% (23/25) in the control group, no significant difference was found (p =1.000). The median duration of stent patency was significantly longer in the 125I brachytherapy group compared with the control group (289 days vs. 88 days, respectively, p =0.001). The 125I brachytherapy group demonstrated a significantly better median overall survival rate than the control group (221 days vs. 78 days, respectively, p =0.001). In multivariate analysis, stents with 125I brachytherapy (p =0.004) was a significant favorable prognostic factor that affected patient survival. No significant difference was observed between CT-guided 125I seed implantation and 125I seed strand insertion in stent patency (p =0.268), and overall survival (p =0.483). Conclusion SEMS combined with 125I brachytherapy is safe and effective for treating MOJ. 125I brachytherapy may help to maintain stent patency and prolong overall survival. There was no significant difference between CT-guided 125I seed implantation with SEMS and 125I seed strand insertion with SEMS in stent patency and overall survival

Identification of Loci for Four Important Agronomic Traits in Loose-Curd Cauliflower Based on Genome-Wide Association Studies

Cauliflower is a nutritious vegetable with inflorescences that are specialized to form the edible organs called curds. Uncovering key genes underlying important traits is crucial for the genetic improvement of this important crop. However, the genetic basis of many important agronomic traits, including curd performance and plant architecture in cauliflower, remains unclear. GWASs have proved to be powerful tools to study agronomic traits in many crops. To reveal the genetic basis of four important agronomic traits, namely, the main stem height (MSH), purplish curd (PC), external leaf wing (ELW) and weight of a single curd (WSC), we selected 220 core accessions of loose-curd cauliflower for resequencing, phenotypic investigation and GWAS. The approach revealed significant novel loci. We detected several significant associations: on C02 for MSH and PC, on C06 for ELW and on C01 for WSC. More interestingly, we identified a significant single-peak signal for the weight of a single curd (WSC), an important yield trait, and within this signal interval, we identified the BOB01G136670 gene with five SNPs encoding nonsynonymous mutations in the CDS region; these mutations resulted in two haplotypes with significant differences in curd weight. The weight of a single curd was significantly increased in the varieties with the BOB01G136670 Hap1 allele compared to those with BOB01G136670 Hap2. BOB01G136670 was highly conserved with the homologous genes that encode serine carboxypeptidase and belong to the S10 family in other species, including GS5, which functions as a positive regulator of grain size in rice, wheat and maize. Additionally, BOB01G136670 was highly expressed specifically at the curd enlargement stage, with low or even no expression at all in other tissues and stages, indicating that BOB01G136670 is a plausible candidate gene for WSC. Overall, this study identified genomic loci for four important agronomic traits that are relevant for accelerating biological breeding and the improvement of cauliflower varieties