Amplification of light pulses with orbital angular momentum (OAM) in nitrogen ions lasing.

Nitrogen ions pumped by intense femtosecond laser pulses give rise to optical amplification in the ultraviolet range. Here, we demonstrated that a seed light pulse carrying orbital angular momentum (OAM) can be significantly amplified in nitrogen plasma excited by a Gaussian femtosecond laser pulse. With the topological charge of ℓ = ±1, we observed an energy amplification of the seed light pulse by two orders of magnitude, while the amplified pulse carries the same OAM as the incident seed pulse. Moreover, we show that a spatial misalignment of the plasma amplifier with the OAM seed beam leads to an amplified emission of Gaussian mode without OAM, due to the special spatial profile of the OAM seed pulse that presents a donut-shaped intensity distribution. Utilizing this misalignment, we can implement an optical switch that toggles the output signal between Gaussian mode and OAM mode. This work not only certifies the phase transfer from the seed light to the amplified signal, but also highlights the important role of spatial overlap of the donut-shaped seed beam with the gain region of the nitrogen plasma for the achievement of OAM beam amplification.

[Genetic analysis of two families with Short-rib thoracic dysplasia type 3].

OBJECTIVE: To explore the pathogenic variants and clinical classification of two fetuses with Short-rib thoracic dysplasia with or without polydactyly (SRTD). METHODS: With informed consent obtained, the phenotypic characteristics of the fetuses were comprehensively examined, and genomic DNA was extracted from fetal skin tissue and peripheral blood samples of the parents with conventional phenol-chloroform method. Whole exome sequencing (WES) was carried out on both fetuses, and the candidate variants were validated by Sanger sequencing. The pathogenicity of the candidate variants was analyzed using bioinformatic software VarCards, and the impact of the variants on the protein structure was predicted with Swiss-Pdb-viewer. RESULTS: Both fetuses were found to harbor compound heterozygous variants of the DYNC2H1 gene, including c.515C>A (p.Pro172Gln) and c.5983G>A (p.Ala1995Thr) in fetus 1, and c.5920G>T (pGly1974) and c.9908T>C (p.He3303Thr) in fetus 2. The parents of both fetuses were heterozygous carriers. CONCLUSION: The compound heterozygous variants of the DYNC2H1 gene probably underlay the SRTD3 in the two fetuses.

Subfemtosecond-resolved modulation of superfluorescence from ionized nitrogen molecules by 800-nm femtosecond laser pulses.

Superfluorescence emission around 391 nm is generated when nitrogen molecules are irradiated by a strong 800-nm pump laser and a delayed seed laser. The emission corresponds to the transition between N2+(B2Σu+,ν″=0) and N2+(X2Σg+,ν=0). When another weak 800-nm probe laser is injected and scanned after the pump laser, the superfluorescence intensity is observed to exhibit periodical modulation. The period is determined to be ~2.63 fs, corresponding to the transition frequency between N2+(A2Πu,ν'=2) and N2+(X2Σg+,ν=0). Based on theoretical derivation, these observations can be attributed to the laser-induced population transfer and polarization variation between the relevant electronic states of ionized nitrogen molecules.

Controlling the Polarization of Nitrogen Ion Lasing.

Air lasing provides a promising technique to remotely produce coherent radiation in the atmosphere and has attracted continuous attention. However, the polarization properties of N2+ lasing with seeding have not been understood since it was discovered 10 years ago, in which the polarization behaviors appear disordered and confusing. Here, we performed an experimental and theoretical investigation of the polarization properties of N2+ lasing and successfully revealed its underlying physical mechanism. We found that the optical gain is anisotropic, owing to the permanent alignment of N2+ induced by the preferential ionization of the pump light. As a result, the polarization of the N2+ lasing tends to align with that of the pump light after amplification, which becomes more pronounced as the amplification factor increases. Based on the permanent alignment of N2+, we built a theoretical model that analytically interpreted and numerically reproduced the experimental observations, which points out the key factors for controlling the polarization of N2+ lasing.

Effect of synthesis temperature on the structural morphology of a metal-organic framework and the capacitor performance of derived cobalt-nickel layered double hydroxides.

Three-dimensional interconnected nickel-cobalt layered double hydroxides (NiCo-LDHs) were prepared on nickel foam by ion exchange using a cobalt-based metal-organic framework (Co-MOF) as a template at different temperatures. The effects of the Co-MOF preparation temperature on the growth, mass, morphology, and electrochemical properties of the Co-MOF and derived NiCo-LDH samples were studied. The synthesis temperature from 30 to 50 °C gradually increased the mass of the active material and the thickness of the Co-MOF sheets grown on the nickel foam. The higher the temperature is, the larger the proportion of Co3+. ß-Cobalt hydroxide (ß-Co(OH)2) sheets were generated above 60 °C. The morphology and mass loading pattern of the derived flocculent layer clusters of NiCo-LDH were inherited from metal-organic frameworks (MOFs). The areal capacitance of NiCo-LDH shows an inverted U-shaped curve trend with increasing temperature. The electrode material synthesized at 50 °C had a tremendous specific capacitance of 7631 mF·cm-2 at a current density of 2 mA·cm-2. The asymmetric supercapacitor assembled with the sample and active carbon (AC) achieved an energy density of 55.0 Wh·kg-1 at a power density of 800.0 W·kg-1, demonstrating the great potential of the NiCo-LDH material for energy storage. This work presents a new strategy for designing and fabricating advanced green supercapacitor materials with large power and energy densities.

Erratum to "3D collagen matrices modulate the transcriptional trajectory of bone marrow hematopoietic progenitors into macrophage lineage commitment" [Bioact. Mater. 10C (April 2022) 255-268].

[This corrects the article DOI: 10.1016/j.bioactmat.2021.08.032.].

Dimensional-matched two dimensional/two dimensional TiO2/Bi2O3 step-scheme heterojunction for boosted photocatalytic performance of sterilization and water splitting.

A Step-scheme (S-scheme) heterojunction can regulate the directional migration of powerful photogenerated carriers and realize high photocatalytic activity. Herein, we propose a novel dimensional matched S-scheme photocatalyst comprising of two-dimensional (2D) TiO2 nanosheets and 2D Bi2O3 nanosheets for environmental and energy applications, such as water sterilization and water splitting. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance, in-situ irradiated XPS and theoretical calculations provided strong evidence that the photocarrier migration in the TiO2/Bi2O3 composite followed the S-scheme mode, which efficiently prevented the recombination of powerful photocarriers, thereby enabling the heterojunction with a strong redox ability for producing abundant reactive oxygen species. The tight and large 2D/2D interface minimized the distance of photocarrier migration to further extend the lifetime of useful photocarriers (active radicals for sterilization and photoelectrons for H2 generation). The 2D/2D TiO2/Bi2O3 heterojunction demonstrated an improved photocatalytic antibacterial performance with complete inactivation of 4.63 × 107 CFU mL-1Escherichia coli cells within 6 h in water. In addition, the heterojunction displayed a H2 generation rate of 12.08 mmol h-1g-1 through water splitting process. This study provides a potential bifunctional photocatalyst for minimizing the adverse impact of pollution on the environment.

3D collagen matrices modulate the transcriptional trajectory of bone marrow hematopoietic progenitors into macrophage lineage commitment.

Physical signals provided by the extracellular matrix (ECM) are key microenvironmental parameters for the fate decision of hematopoietic stem and progenitor cells (HSPC) in bone marrow. Insights into cell-ECM interactions are critical for advancing HSC-based tissue engineering. Herein, we employed collagen hydrogels and collagen-alginate hydrogels of defined stiffness to study the behaviors of hematopoietic progenitor cells (HPCs). Three-dimensional (3D) collagen hydrogels with a stiffness of 45 Pa were found to promote HPC maintenance and colony formation of monocyte/macrophage progenitors. Using single-cell RNA sequencing (scRNA-seq), we also characterized the comprehensive transcriptional profiles of cells randomly selected from two-dimensional (2D) and 3D hydrogels. A distinct maturation trajectory from HPCs into macrophages within the 3D microenvironment was revealed by these results. 3D-derived macrophages expressed high levels of various cytokines and chemokines, such as Saa3, Cxcl2, Socs3 and Tnf. Furthermore, enhanced communication between 3D-macrophages and other hematopoietic clusters based on ligand-repair interactions was demonstrated through bioinformatic analyses. Our research underlines the regulatory role of matrix-dimensionality in HPC differentiation and therefore probably be applied to the generation of specialized macrophages.

Improvement of alkali metal ion batteries via interlayer engineering of anodes: from graphite to graphene.

Interlayer engineering of graphite anodes in alkali metal ion (M = Li, Na, and K) batteries is carried out based on the first-principles calculations. By increasing the interlayer spacing of graphite, the specific capacity of Li or Na does not increase while that of K increases continuously (from 279 mA h g-1 at the equilibrium interlayer spacing to 1396 mA h g-1 at the interlayer spacing of 20.0 Å). As the interlayer spacing increases, the electrostatic potential of graphite becomes smoother, and the ability to buffer the electrostatic potential fluctuation becomes poorer in M ions. These two effects jointly lead to minima of the diffusion barrier of M ions on graphite (0.01-0.05 eV), instead of strictly monotonous declines with the increasing interlayer spacing. To perform the interlayer engineering of anode candidates more efficiently, a set of high-throughput programs has been developed and can be easily applied to other systems. Our research has guiding significance for achieving the optimal effect in interlayer engineering experimentally.

Study of the Formation Dynamics of OH from the Photolysis of O3 by Ultrashort Laser Pulses.

We report the first experimental detection of the laser-induced formation dynamics of OH under normal pressure, which was observed using the pump-probe scheme with two 250 fs laser pulses at 282.2 nm. The first laser photolyzes O3 to form OH, and the second laser excites OH to induce fluorescence at 308 nm. The fluorescence cannot be detected with a single beam because the femtosecond pulses have already passed through the sample before the formation of OH from their own photolysis. A photochemical dynamic model was built, and the experimental results are in good agreement with the model. This method can also be used for other OH-related dynamic measurements, which can effectively avoid laser-generated interference from the photolysis of O3.

Spatial distribution of and historical changes in heavy metals in the surface seawater and sediments of the Beibu Gulf, China.

To study the impact of rapid industrialization and urbanization in Guangxi Province on the coastal environment in recent years, seven metals (Hg, Cu, Pb, Cd, Cr, Zn and As) were investigated in the surface seawater and sediments of the northern Beibu Gulf. The levels of the metals were lower than in other regions in China, but Hg, Cu and Cd showed a significant increasing trend in both seawater and sediments over the past 20 years. Higher levels were consistently observed in the nearshore area, particularly in the northwest, which may be related to the rapid industrial development in coastal areas. Correlation and principal component analyses suggested that both terrestrial inputs and biological processes influenced the distribution of metals. In addition, the higher risk observed for Hg and Cu may be largely influenced by the increasing trend in these metals in the Beibu Gulf.

Photoluminescence enhancement in Yb(3+):Er(3+)co-doped eutectic Al(2)O(3): SiO(2) thin films by 980nm excitation.

Si nanocrystals (nc-Si) are addressed in the eutectic Al(2)O(3):SiO(2) thin films co-doped with Er(3+) and Yb(3+) by the laser-induced crystallization (LIC). The thin films are originally synthesized on a silica-on-silicon (SOS) substrate by the microwave electron cyclotron resonance (MW-ECR) plasma source enhanced RF sputtering. Raman spectroscopy has revealed that the strong crystallization occurs with the emergence of the nc-Si in the eutectic Al(2)O(3): SiO(2) layer during the liquid phase transformation. The dual wavelength energy transfer mechanism at 800nm and 980nm induced by 980nm excitation in nc-Si and Yb sensitized Er doped system has been proposed and demonstrated. A tenfold photoluminescence enhancement has been obtained from this mechanism.

siRNA agents inhibit oncogene expression and attenuate human tumor cell growth.

Cancer is a genomic functional disease with features of oncogene activation and tumor suppressor inactivation. These genomic features have resulted in the limited effectiveness of conventional therapies and therefore forced considerable efforts to explore new types of anticancer agents. It has been clear that chemically synthesized or in vivo-expressed short interfering RNA (siRNA) can specifically and effectively direct homology-dependent post-transcriptional gene silencing. In the present study, we intended to investigate whether siRNA could suppress the proliferation of human cancer cells through interfering oncogene activities and recovering the functions of tumor-suppressor gene. Single siRNA or combinatorial siRNAs were successfully transfected into HeLa cells, lung adenocarcinoma cells, hepatoma cells, ovarian carcinoma cells, and melanoma cells with cationic lipid complexes. These siRNA molecules not only specifically knocked down their cognate targets such as bcl-2, cdk-2, mdm-2, pkc-alpha, tgf-beta1, H-ras, vegf, and GFP mRNAs, but also effectively suppressed the proliferation of cancer cells to different extents. These data suggest that (1) all these human cancer cells preserve RNAi machinery; (2) chemically synthesized and vector-driven siRNAs can be incorporated into intrinsic RNAi system for silencing target mRNA molecules; and (3) the combination of different siRNAs inhibits the growth and proliferation of cancer cells.

Quantification of bcr/abl mRNA expression level in leukemia cells by FQ-RT-PCR.

OBJECTIVE: To establish a fluorogenic probe quantitative RT-PCR (FQ-RT-PCR) method for detection of bcr/abl mRNA fusion gene expression level in leukemia cells, and provide a useful tool for leukaemia diagnosis and minimal residual disease inspectation. METHOD: The conventional RT-PCR was used to amplify bcr/abl gene from cultured K562 cells, the quantitative standard template was constructed with A-T clone method. The fluo-rogenic quantitative RT-PCR method by using Applied Biosystems 7700 Sequence Detector for detecting the expression of bcr/abl fusion gene was successfully. The sensitivity, stability and repetitiveness of this method was determined. The peripheral blood samples from 14 CML patients, one of whom before and one month after bone marrow transplantation (BMT) and 4 cases of ALL in the early stages were detected. RESULTS: The sensitivity of FQ-RT-PCR for detecting bcr/abl fusion gene was about 10(-5) micro g RNA from K562 cell and 10 copies recombined plasmid. The repetition CT value (cycle threshold) and the coefficient variation (CV) among tubes and batches were 2.0% and 3.7%, respectively. The median bcr/abl fusion gene expression level of 14 CML patients was 5.15 x 10(4) copies/ micro g RNA. The products analyzed by electrophoresis showed that 11 cases were b2a2 and 3 cases b3a2. 1.2 x 10(5) copies/ micro g RNA in one CML patient before BMT was changed to 2.3 x 10(3) copies/ micro g RNA one month after BMT. B2a2 was observed in one of the four (25.0%) patients with ALL, and its level of expression was 8.2 x 10(5) copies/ micro g RNA. CONCLUSION: The established FQ-RT-PCR method is sensitive, specific, reliable, accurate and good at repetitiveness. The results expressed in copies were easy for evaluation and comparation. Two different bcr/abl fusion gene form - b2a2, b3a2 can be detected by the method. It can be widely applied to diagnosis and detection of minimal residual disease for CML and some ALL patients.

[Expression and clinical significance of mdr-1 gene in lymphoma].

BACKGROUND & OBJECTIVE: It is still unclear whether overexpression of mdr-1 gene play a role in the chemotherapy resistance of lymphoma. This study was designed to investigate P-glycoprotein(P-gp) and mdr-1 mRNA levels of lymphoma and to observed the impact of P-gp level upon chemotherapy response. METHODS: Ten samples of relapsed lymphoma and 21 samples of untreated lymphoma were assessed by flow cytometry(FCM). The mdr-1 mRNA levels were determined by real-time reverse-transcription PCR assay simultaneously in eighteen samples. The impact of P-gp levels upon chemotherapy response was observed in seventeen patients. RESULTS: Nineteen Percent (4/21) patients overexpressed P-gp at diagnosis as compared to 60%(6/10) in relapse(P = 0.012). The copy numbers of mdr-1 mRNA were 4 x 10(2)-1.32 x 10(4) copies/microgram RNA in untreated group and 4 x 10(2)-4 x 10(4) copies/microgram RNA in recurrent group. There existed significant difference in the distribution of mdr-1 mRNA expression between these two groups, P < 0.05. The complete response rates were 46% (6/13) in P-gp non-overexpression group and 25% (1/4) in P-gp overexpression group(P = 0.60). CONCLUSION: Relapsed lymphomas highly express P-gp and mdr-1 mRNA. The overexpression of mdr-1 gene may play a role in the multidrug resistance of relapsed lymphoma.

Telomerase activity in gastric cancer and its clinical implications.

AIM:To study the telomerase expression in gastric carcinoma and its clinical implications.METHODS:Telomerase activity was examined in gastric cancer and corresponding normal tissues using a modified TRAP (telomeric repeat amplify-cation protocol) assay (TRAP-eze) in tissue samples from 94 gastric carcinomas and 58 normal tissues, 12 gastric adenomas and 9 gastric ulcer lesions.RESULTS:Telomerase activity was present in 81 of the 94 (86.2%) gastric cancer tissues, whereas no telomerase activity was detected in any normal tissues.The incidence of telomerase activity in gastric cancer tissues was unrelated to the tumor diameter, histological grade, tumor invasion in depth, lymph node metastasis and TNM stage.CONCLUSION:Telomerase plays an important role in carcinogenesis and progression of gastric cancer, and it is suggested to be a useful tumor marker.