ADAR-mediated RNA editing regulates PVR immune checkpoint in colorectal cancer

Recent studies have revealed that tumor immunotherapy resistance is influenced by ADAR-mediated RNA editing, but its targets remain unelucidated. Our current study identified the poliovirus receptor (PVR) oncogene, which encodes an immune checkpoint in colorectal cancer (CRC), as a potential target for RNA editing. We performed transcriptome sequencing analysis and experimental validation in two Chinese CRC cohorts. PVR and ADAR expressions significantly increased in CRC tumors and showed positive correlations in both cohorts, coupled with upregulated PVR RNA editing in CRC tumors. Manipulation of ADAR expression by over-expression or knockdown substantially changed PVR expression and RNA editing in HTC116 CRC cells. Luciferase reporter and actinomycin D assays further revealed that RNA editing in PVR 3'-UTR could upregulate PVR RNA expression, probably by increasing the RNA stability. By increasing PVR expression, ADAR-mediate RNA editing might contribute to tumor- and immune-related gene functions and pathways in CRC. Moreover, a signature combining PVR RNA editing and expression showed promising predictive performance in CRC diagnosis in both Chinese CRC cohorts. Our findings thus highlight the importance of ADAR-mediated RNA editing in PVR up-regulation in CRC tumors and provide new insight into the application of PVR RNA editing as a novel diagnostic biomarker for CRC.

Preparation of Matrix Product States with Log-Depth Quantum Circuits

We consider the preparation of matrix product states (MPS) on quantum devices via quantum circuits of local gates. We first prove that faithfully preparing translation-invariant normal MPS of N sites requires a circuit depth T=Ω(logN). We then introduce an algorithm based on the renormalization-group transformation to prepare normal MPS with an error ε in depth T=O[log(N/ε)], which is optimal. We also show that measurement and feedback leads to an exponential speedup of the algorithm to T=O[loglog(N/ε)]. Measurements also allow one to prepare arbitrary translation-invariant MPS, including long-range non-normal ones, in the same depth. Finally, the algorithm naturally extends to inhomogeneous MPS.

Comparative Analysis of Molecular Landscape in Mouse Models and Patients Reveals Conserved Inflammation Pathways in Age-Related Macular Degeneration

Purpose

The purpose of this study was to identify key genes and their regulatory networks that are conserved in mouse models of age-related macular degeneration (AMD) and human AMD.

Methods

Retinal RNA-Seq was performed in laser-induced choroidal neovascularization (CNV) mice at day 3 and day 7 after photocoagulation. Mass spectrometry-based proteomic analysis was performed with retinas collected at day 3. Retinal RNA-Seq data was further compared among mouse models of laser-induced CNV and NaIO3-induced retinal degeneration (RD) and a large AMD cohort.

Results

Retinal RNA-Seq revealed upregulated genes and pathways related to innate immunity and inflammation in mice with CNV, with more profound changes at the early stage (day 3). Proteomic analysis further validated these differentially expressed genes and their networks in retinal inflammation during CNV. Notably, the most evident overlap in the retina of mice with laser-induced CNV and NaIO3-induced RD was the upregulation of inflammation-related genes, pointing to a common vital role of retinal inflammation in the early stage for both mouse AMD models. Further comparative transcriptomic analysis of the mouse AMD models and human AMD identified 48 conserved genes mainly involved in inflammation response. Among them, B2M, C3, and SERPING1 were upregulated in all stages of human AMD and the mouse AMD models compared to controls.

Conclusions

Our study demonstrates conserved molecular changes related to retinal inflammation in mouse AMD models and human AMD and provides new insight into the translational application of these mouse models in studying AMD mechanisms and treatments.

The age-related characteristics in bone microarchitecture, osteoclast distribution pattern, functional and transcriptomic alterations of BMSCs in mice

Deteriorated age-related bone loss is the hallmarks of skeletal aging. However, how the aging of bone marrow mesenchymal stem cells (BMSCs) and osteoclasts are linked to the bone microstructure degeneration is not yet very clear. In this study, the characteristics of age-related bone loss, distribution patterns of osteoclasts, functional and transcriptomic alterations of BMSCs, hub genes responsible for BMSCs senescence, were analyzed. Our study revealed an age-related declined trends in trabecular and cortical bones of femur, tibia and lumbar vertebra in mice, which was accompanied by a shift from the trabecular to cortical bones in osteoclasts. Additionally, middle-aged or aged mice exhibited remarkably reduced dynamic bone formation capacities, along with reversed osteogenic-adipogenic differentiation potentials in BMSCs. Finally, transcriptomic analysis indicated that aging-related signaling pathways were significantly activated in BMSCs from aged mice (e.g., cellular senescence, p53 signaling pathway, etc.). Also, weighted correlation network analysis (WGCNA) and venn diagram analysis based on our RNA-Seq data and GSE35956 dataset revealed the critical role of PTPN1 in BMSCs senescence. Targeted inhibition of PTP1B with AAV-Ptpn1-RNAi dramatically postponed age-related bone loss in middle-aged mice. Collectively, our study has uncovered the age-dependent cellular characteristics in BMSCs and osteoclasts underlying progressive bone loss with advancing age.

Epitranscriptomic investigation of myopia-associated RNA editing in the retina

Myopia is one of the most common causes of vision loss globally and is significantly affected by epigenetics. Adenosine-to-inosine (A-to-I RNA) editing is an epigenetic process involved in neurological disorders, yet its role in myopia remains undetermined. We performed a transcriptome-wide analysis of A-to-I RNA editing in the retina of form-deprivation myopia mice. Our study identified 91 A-to-I RNA editing sites in 84 genes associated with myopia. Notably, at least 27 (32.1%) of these genes with myopia-associated RNA editing showed existing evidence to be associated with myopia or related ocular phenotypes in humans or animal models, such as very low-density lipoprotein receptor (Vldlr) in retinal neovascularization and hypoxia-induced factor 1 alpha (Hif1a). Moreover, functional enrichment showed that RNA editing enriched in FDM was primarily involved in response to fungicides, a potentially druggable process for myopia prevention, and epigenetic regulation. In contrast, RNA editing enriched in controls was mostly involved in post-embryonic eye morphogenesis. Our results demonstrate altered A-to-I RNA editing associated with myopia in an experimental mouse model and warrant further study on its role in myopia development.

Gastric juice microbiota in pediatric chronic gastritis that clinically tested positive and negative for Helicobacter pylori

Purpose

Helicobacter pylori (HP) infection is an identified risk factor for pediatric chronic gastritis (PCG), but its impact on gastric juice microbiota (GJM) remains to be further elucidated in PCG. This study aimed to analyze and compare the microbial communities and microbial interactive networks of GJM in PCG that clinically tested positive and negative for HP (HP+ and HP-, respectively).

Methods

A total of 45 PCG patients aged from 6 to 16 years were recruited, including 20 HP+ and 25 HP- patients tested by culture and rapid urease test. Gastric juice samples were collected from these PCG patients and subjected to high-throughput amplicon sequencing and subsequent analysis of 16S rRNA genes.

Results

While no significant change in alpha diversity, significant differences in beta diversity were observed between HP+ and HP- PCG. At the genus level, Streptococcus, Helicobacter, and Granulicatella were significantly enriched in HP+ PCG, whereas Campylobacter and Absconditabacteriales (SR1) were significantly enriched in HP- PCG. Network analysis showed that Streptococcus was the only genus positively correlated with Helicobacter (r = 0.497) in the GJM network of overall PCG. Moreover, compared to HP- PCG, HP+ PCG showed a reduction in microbial network connectivity in GJM. Netshift analysis identified driver microbes including Streptococcus and other four genera, which substantially contributed to the GJM network transition from HP- PCG to HP+ PCG. Furthermore, Predicted GJM function analysis indicated up-regulated pathways related to the metabolism of nucleotides, carbohydrates, and L-Lysine, the urea cycle, as well as endotoxin peptidoglycan biosynthesis and maturation in HP+ PCG.

Conclusion

GJM in HP+ PCG exhibited dramatically altered beta diversity, taxonomic structure, and function, with reduced microbial network connectivity, which could be involved in the disease etiology.

[Analysis of clinical manifestations and imaging characteristics of in vivo confocal microscopy for Nocardia keratitis]

Objective: To analyze the clinical manifestations and imaging characteristics of in vivo confocal microscopy (IVCM) for Nocardia keratitis. Methods: It was a retrospective case series study. Medical records of 16 consecutive patients (16 eyes) with Nocardia keratitis were collected from the Department of Ophthalmology at Beijing Tongren Hospital, Capital Medical University between 2018 and 2022. The group consisted of 11 males and 5 females. The inclusion criteria for the study were the presence of typical clinical manifestations of Nocardia keratitis and at least one positive pathogenic test (corneal scraping or microbial culture) indicating Nocardia infection. The medical history, clinical and microbiological examination data of the patients were analyzed, including risk factors, diagnosis time, clinical manifestations, diagnostic methods, strain isolation, cure time, and best corrected visual acuity before and after treatment. This study utilized techniques such as slit lamp microscopy, in vivo confocal microscopy (IVCM), scraping cytology, microbial culture, and mass spectrometry identification. Results: The main risk factors for Nocardia keratitis included plant or foreign body injuries (5 out of 16 cases), contact lens use (4 out of 16 cases), and surgery (2 out of 16 cases). The average time to diagnosis was (20.8±11.8) days, with the shortest time being 8 days and the longest being 60 days. The best corrected visual acuity was less than 0.05 in 7 patients, between 0.05 to 0.3 in 7 patients, and greater than or equal to 0.3 in 2 patients. The typical symptoms included superficial gray-white infiltration in a wreath-like pattern on the cornea, corneal ulcers with dry and gray-white necrotic tissue coverage, and in severe cases, corneal ulcer perforation. Nocardia corneal infection was identified in 12 out of 16 cases by scraping cytology, 9 out of 16 cases by mass spectrometry, and 8 out of 16 cases by both methods. IVCM showed the presence of fine and moderately reflective filamentous hyphae in the subepithelial and superficial stromal layer of the cornea, arranged in elongated, beaded, and branched structures. Infiltration of many hyper-reflective round inflammatory cells was also seen around the hyphae. Fourteen cases were treated with medication and 2 cases were treated with corneal transplantation. The average cure time was (37.5±25.2) days and there were no cases of recurrence during the follow-up period (all greater than 6 months). Conclusions: Nocardia keratitis is primarily characterized by dense, round, or wreath-like infiltration in the early stage, and by gray-white dry necrotic secretion and hypopyon on the surface of corneal ulcers in the middle and late stages. Fine, branched or beaded, and moderately reflective filamentous structures are the hallmark of the corneal lesion on the IVCM images.

Host A-to-I RNA editing signatures in intracellular bacterial and single-strand RNA viral infections

Background

Microbial infection is accompanied by remodeling of the host transcriptome. Involvement of A-to-I RNA editing has been reported during viral infection but remains to be elucidated during intracellular bacterial infections.

Results

Herein we analyzed A-to-I RNA editing during intracellular bacterial infections based on 18 RNA-Seq datasets of 210 mouse samples involving 7 tissue types and 8 intracellular bacterial pathogens (IBPs), and identified a consensus signature of RNA editing for IBP infections, mainly involving neutrophil-mediated innate immunity and lipid metabolism. Further comparison of host RNA editing patterns revealed remarkable similarities between pneumonia caused by IBPs and single-strand RNA (ssRNA) viruses, such as altered editing enzyme expression, editing site numbers, and levels. In addition, functional enrichment analysis of genes with RNA editing highlighted that the Rab GTPase family played a common and vital role in the host immune response to IBP and ssRNA viral infections, which was indicated by the consistent up-regulated RNA editing of Ras-related protein Rab27a. Nevertheless, dramatic differences between IBP and viral infections were also observed, and clearly distinguished the two types of intracellular infections.

Conclusion

Our study showed transcriptome-wide host A-to-I RNA editing alteration during IBP and ssRNA viral infections. By identifying and comparing consensus signatures of host A-to-I RNA editing, our analysis implicates the importance of host A-to-I RNA editing during these infections and provides new insights into the diagnosis and treatment of infectious diseases.

[A case of bilateral corneal ulcer after left eye cataract extraction surgery]

The patient is a 73-year-old female who developed bilateral corneal ulcers one month after cataract surgery in her left eye. The diagnosis is bilateral conjunctival pemphigoid. She underwent a left-eye amniotic membrane transplant and a right-eye lamellar corneal transplant, and was treated with oral immunosuppressants. The patient's condition is stable.

[A case report of congenital osteogenesis imperfacta with corneal ectasia]

An 8-year-old male patient was admitted to ophthalmology for bilateral progressive blurred vision for 5 years. He had a history of multiple spontaneous fractures. Ocular examination revealed best-corrected visual acuity (BCVA) of 0.5 in the right eye and 0.6 in the left eye. Slitlamp examination showed bilateral blue sclerae, thining of the entire cornea and corneal ectasia. General physical examination demonstrated multi-site ligamentous laxity. The diagnosis of osteogenesis imperfacta was made. The patient was advised to wear rigid gas permeable contact lens with large diameter and stabilized peripheral curve, and the BCVA achieved 0.8 for both eyes.

[A case of bacterial keratitis after lamellar keratoplasty for pterygium]

A 48-year-old man presented to Beijing Tongren Hospital Ophthalmology Department with redness, increased secretions and vision loss in his right eye. He had been treated with pterygium excision and lamellar keratoplasty due to recurrent pterygium in the right eye. After corneal scraping and microbial culture, he was diagnosed as bacterial keratitis after pterygium lamellar keratoplasty in the right eye. After applying topical antibiotic eye drops, removing corneal graft and conducting amniotic membrane transplantation, corneal infection was controlled and his vision was recovered.

Brain Epitranscriptomic Analysis Revealed Altered A-to-I RNA Editing in Septic Patients

Recent studies suggest that RNA editing is associated with impaired brain function and neurological and psychiatric disorders. However, the role of A-to-I RNA editing during sepsis-associated encephalopathy (SAE) remains unclear. In this study, we analyzed adenosine-to-inosine (A-to-I) RNA editing in postmortem brain tissues from septic patients and controls. A total of 3024 high-confidence A-to-I RNA editing sites were identified. In sepsis, there were fewer A-to-I RNA editing genes and editing sites than in controls. Among all A-to-I RNA editing sites, 42 genes showed significantly differential RNA editing, with 23 downregulated and 19 upregulated in sepsis compared to controls. Notably, more than 50% of these genes were highly expressed in the brain and potentially related to neurological diseases. Notably, cis-regulatory analysis showed that the level of RNA editing in six differentially edited genes was significantly correlated with the gene expression, including HAUS augmin-like complex subunit 2 (HAUS2), protein phosphatase 3 catalytic subunit beta (PPP3CB), hook microtubule tethering protein 3 (HOOK3), CUB and Sushi multiple domains 1 (CSMD1), methyltransferase-like 7A (METTL7A), and kinesin light chain 2 (KLC2). Furthermore, enrichment analysis showed that fewer gene functions and KEGG pathways were enriched by edited genes in sepsis compared to controls. These results revealed alteration of A-to-I RNA editing in the human brain associated with sepsis, thus providing an important basis for understanding its role in neuropathology in SAE.

Transplantation of Gut Microbiota From High-Fat-Diet-Tolerant Cynomolgus Monkeys Alleviates Hyperlipidemia and Hepatic Steatosis in Rats

Emerging evidence has been reported to support the involvement of the gut microbiota in the host's blood lipid and hyperlipidemia (HLP). However, there remains unexplained variation in the host's blood lipid phenotype. Herein a nonhuman primate HLP model was established in cynomolgus monkeys fed a high-fat diet (HFD) for 19 months. At month 19%, 60% (3/5) of the HFD monkeys developed HLP, but surprisingly 40% of them (2/5) exhibited strong tolerance to the HFD (HFD-T) with their blood lipid profiles returning to normal levels. Metagenomic analysis was used to investigate the compositional changes in the gut microbiota in these monkeys. Furthermore, the relative abundance of Megasphaera remarkably increased and became the dominant gut microbe in HFD-T monkeys. A validation experiment showed that transplantation of fecal microbiota from HFD-T monkeys reduced the blood lipid levels and hepatic steatosis in HLP rats. Furthermore, the relative abundance of Megasphaera significantly increased in rats receiving transplantation, confirming the successful colonization of the microbe in the host and its correlation with the change of the host's blood lipid profiles. Our results thus suggested a potentially pivotal lipid-lowering role of Megasphaera in the gut microbiota, which could contribute to the variation in the host's blood lipid phenotype.

Characterization of Changes and Driver Microbes in Gut Microbiota During Healthy Aging Using A Captive Monkey Model

Recent population studies have significantly advanced our understanding of how age shapes the gut microbiota. However, the actual role of age could be inevitably confounded due to the complex and variable environmental factors in human populations. A well-controlled environment is thus necessary to reduce undesirable confounding effects, and recapitulate age-dependent changes in the gut microbiota of healthy primates. Herein we performed 16S rRNA gene sequencing, characterized the age-associated gut microbial profiles from infant to elderly crab-eating macaques reared in captivity, and systemically revealed the lifelong dynamic changes of the primate gut microbiota. While the most significant age-associated taxa were mainly found as commensals such as Faecalibacterium, the abundance of a group of suspicious pathogens such as Helicobacter was exclusively increased in infants, underlining their potential role in host development. Importantly, topology analysis indicated that the network connectivity of gut microbiota was even more age-dependent than taxonomic diversity, and its tremendous decline with age could probably be linked to healthy aging. Moreover, we identified key driver microbes responsible for such age-dependent network changes, which were further linked to altered metabolic functions of lipids, carbohydrates, and amino acids, as well as phenotypes in the microbial community. The current study thus demonstrates the lifelong age-dependent changes and their driver microbes in the primate gut microbiota, and provides new insights into their roles in the development and healthy aging of their hosts.

[Detection of the spontaneous blinking pattern of dry eye patients using the machine learning method]

Objective: To establish a method to record the spontaneous blink pattern with a machine learning model, and to clarify the spontaneous blink pattern in patients with dry eye. Methods: It was a cross-setional study.We selected 357 dry eye patients (102 males and 255 females), aged (46.2±13.3) years, who visited corneal specialist clinics of Beijing Tongren Eye Center in 2019, as the dry eye group. The control group enrolled 152 normal controls, including 32 males and 120 females, aged (48.1±13.9) years. All participants completed the Ocular Surface Disease Index questionnaire, blink video capture, lipid layer thickness measurement, tear break-up time measurement, corneal fluorescein staining, and Schirmer Ⅱ test. Based on the assembled model built using UNet image segmentation algorithm and ResNet image classification algorithm, single frames of the blink video were analyzed, and then the palpebral opening height of each frame was obtained in order to establish a spontaneous blink wave. Finally, the characteristics of spontaneous blinks in dry eye patients were analyzed based on different types of complete blinks (types A, B and C) and partial blinks (types Ⅰ, Ⅱ and Ⅲ). Independent sample t test and Wilcoxon rank-sum test were used to judge if there was significant difference between the dry eye group and the normal group. Results: The accuracy of the segmentation model and the classification model was 96.3% and 96.0%, respectively, and the consistency with the manual analysis was 97.9%. In dry eye patients, the number of blinks was 30 (18, 42)/min, which was higher than that in normal controls [20 (9, 46)/min] (U=18 132.50, P=0.002). The number of complete blinks in dry eye cases was significantly lower than that in normal controls [6 (3, 24)/min vs. 12 (3,33)/min; U=12 361.00, P=0.016], and the number of partial blinks was significantly higher than that in normal controls [15 (6, 27)/min vs. 3 (0, 10)/min; U=22 839.00, P<0.001]. In complete blinks, the proportion of type A blinks in dry eye patients was significantly higher than that in normal controls [53.7% (2 796/5 177) vs. 39.3% (633/1 698); χ²=101.83, P<0.001]; in partial blinks, the proportion of type Ⅱ blinks in dry eye patients was significantly higher than that in normal controls [36.0%(2 334/6 477) vs. 29.6%(126/426); χ²=6.99, P=0.007]. The average interblink interval of dry eye patients was 1.2 s, which was not significantly different from that of normal controls (1.1 s; U=15 230.00, P=0.093). The eyelid closed phase of dry eye patients was 0.8 s, which was significantly shorter than that of normal controls (1.3 s; U=16 291.50, P=0.006). There were no significant differences in eyelid closing phase, early opening phase and late opening phase between the two groups (all P>0.05). Conclusions: In dry eye patients, the number of partial blinks increased, the number of complete blinks decreased, and the duration of eyelid closed phase shortened significantly. The main blink patterns of dry eye patients included type Ⅱ partial blinks with a reduced closure amplitude and type A complete blinks with a shortened closure time.

Sequential Generation of Projected Entangled-Pair States

We introduce plaquette projected entangled-pair states, a class of states in a lattice that can be generated by applying sequential unitaries acting on plaquettes of overlapping regions. They satisfy area-law entanglement, possess long-range correlations, and naturally generalize other relevant classes of tensor network states. We identify a subclass that can be more efficiently prepared in a radial fashion and that contains the family of isometric tensor network states [M. P. Zaletel and F. Pollmann, Phys. Rev. Lett. 124, 037201 (2020)PRLTAO0031-900710.1103/PhysRevLett.124.037201]. We also show how this subclass can be efficiently prepared using an array of photon sources.

Repeated Winning and Losing Experiences in Chronic Social Conflicts Are Linked to RNA Editing Pattern Difference

Winner-loser effects influence subsequent agonistic interactions between conspecifics. Previous winning experiences could strengthen future aggression and increase the chance of winning the next agonistic interaction, while previous losing experiences could have the opposite effect. Although the role of A-to-I RNA editing has been recently implicated in chronic social defeat stress and aggressive behavior, it remains to be further elucidated in chronic social conflicts in agonistic interactions, especially in the repeated aggression (winners) and repeated defeat (losers) resulted from these conflicts. In the current study, transcriptome-wide A-to-I RNA editing in the dorsal striatum was investigated in a mouse model of chronic social conflicts, and compared between mice repeatedly winning and losing daily agonistic interactions. Our analysis identified 622 A-to-I RNA editing sites in the mouse dorsal striatum, with 23 to be differentially edited in 22 genes, most of which had been previously associated with neurological, psychiatric, or immune disorders. Among these differential RNA editing (DRE) sites four missense variants were observed in neuroligin 2 (Nlgn2), Cdc42 guanine nucleotide exchange factor 9 (Arhgef9) BLCAP apoptosis inducing factor (Blcap), and cytoplasmic FMR1 interacting protein 2 (Cyfip2), as well as two noncoding RNA sites in small nucleolar RNA host gene 11 (Snhg11) and the maternally expressed 3 (Meg3) gene. Moreover, significant changes were observed in gene functions and pathways enriched by genes with A-to-I RNA editing in losers and especially winners compared to controls. Our results demonstrate that repeated winning and losing experiences in chronic social conflicts are linked to A-to-I RNA editing pattern difference, underlining its role in the molecular mechanism of agonistic interactions between conspecifics.

[A randomized controlled trial study of immunogenicity and safety of an inactivated SARS-CoV-2 vaccine in different immunization schedules]

Objective: To compare the immunogenicity and safety of an inactivated SARS-CoV-2 vaccine used for the vaccination in public security officers with different immunization schedules. Methods: From January to February, 2021, 405 public security officers in Taiyuan were randomly divided into 3 groups. Two doses of SARS-CoV-2 inactivated vaccine were injected according to the immunization schedule of 0-14 days, 0-21 days or 0-28 days, respectively. The nucleic acid of SARS-CoV-2 was detected by reverse transcription polymerase chain reaction. The neutralizing antibodies to SARS-CoV-2 were tested by microdose cytopathogenic efficiency assay of live virus. The GMT, seroconversion rate of SARS-CoV-2 neutralizing antibody and safety of the vaccine were analyzed for the 3 groups. Results: The seroconversion rate of SARS-CoV-2 neutralizing antibody was 100% in all the 3 groups. The SARS-CoV-2 neutralizing antibody level of 0-21 day group [166.70 (95%CI: 148.30-185.10)] was similar to that of 0-28 day group [179.50 (95%CI: 156.50-202.60)] (P>0.05), significantly higher than that of 0-14 day group [86.08 (95%CI: 72.36-99.80)] (P<0.001). The incidence rates of adverse reaction in the 3 groups were 1.48% (2/135), 0.74% (1/136) and 1.49% (2/134) respectively (P=0.750), all the adverse reactions were mild. Conclusions: The vaccination of inactivated SARS-CoV-2 vaccine with different immunization schedules in public security officers showed good safety and high seroconversion rate, and the GMTs of SARS-CoV-2 neutralizing antibody in 0-21 day group and 0-28 day group were higher than that in 0-14 day group.

Hybrid de novo Genome Assembly of Erwinia sp. E602 and Bioinformatic Analysis Characterized a New Plasmid-Borne lac Operon Under Positive Selection

Our previous study identified a new β-galactosidase in Erwinia sp. E602. To further understand the lactose metabolism in this strain, de novo genome assembly was conducted by using a strategy combining Illumina and PacBio sequencing technology. The whole genome of Erwinia sp. E602 includes a 4.8 Mb chromosome and a 326 kb large plasmid. A total of 4,739 genes, including 4,543 protein-coding genes, 25 rRNAs, 82 tRNAs and 7 other ncRNAs genes were annotated. The plasmid was the largest one characterized in genus Erwinia by far, and it contained a number of genes and pathways responsible for lactose metabolism and regulation. Moreover, a new plasmid-borne lac operon that lacked a typical β-galactoside transacetylase (lacA) gene was identified in the strain. Phylogenetic analysis showed that the genes lacY and lacZ in the operon were under positive selection, indicating the adaptation of lactose metabolism to the environment in Erwinia sp. E602. Our current study demonstrated that the hybrid de novo genome assembly using Illumina and PacBio sequencing technologies, as well as the metabolic pathway analysis, provided a useful strategy for better understanding of the evolution of undiscovered microbial species or strains.

Cytotoxic T-Cell Trafficking Chemokine Profiles Correlate With Defined Mucosal Microbial Communities in Colorectal Cancer

The involvement of gut microbiota in T-cell trafficking into tumor tissue of colorectal cancer (CRC) remains to be further elucidated. The current study aimed to evaluate the expression of major cytotoxic T-cell trafficking chemokines (CTTCs) and chemokine-associated microbiota profiles in both tumor and adjacent normal tissues during CRC progression. We analyzed the expression of chemokine C-X-C motif ligands 9, 10, and 11 (CXCL9, CXCL10, and CXCL11), and C-C motif ligand 5 (CCL5), characterized gut mucosa-associated microbiota (MAM), and investigated their correlations in CRC patients. Our results showed that the expression of CXCL9, CXCL10, and CXCL11 was significantly higher in tumor than in adjacent normal tissues in 136 CRC patients. Notably, the high expression of CXCL9 in tumor tissues was associated with enhanced CD8⁺ T-cell infiltration and improved survival. Moreover, the MAM in tumor tissues showed reduction of microbial diversity and increase of oral bacteria. Microbial network analysis identified differences in microbial composition and structure between tumor and adjacent normal tissues. In addition, stronger associations between oral bacteria and other gut microbes were observed. Furthermore, the correlation analysis between the defined MAM and individual CTTCs showed that the CTTCs' correlated operational taxonomic units (OTUs) in tumor and adjacent normal tissues rarely overlap with each other. Notably, all the enriched OTUs were positively correlated with the CTTCs in either tumor or adjacent normal tissues. Our findings demonstrated stronger interactions between oral bacteria and gut microbes, and a shifted correlation pattern between MAM and major CTTCs in tumor tissues, underlining possible mechanisms of gut microbiota-host interaction in CRC.

[Correlation of inflammatory cells and corneal nerve damage in fungal keratitis on in vivo confocal microscopy]

Objective: To investigate the relationship between inflammatory cell infiltration and nerve damage in patients with fungal keratitis at different degrees of severity. Methods: Retrospective study. A total of 44 consecutive patients (44 eyes) with fungal keratitis in Beijing Tongren Hospital Affiliated to Capital Medical University from January 2017 to December 2019 were selected as the patient group, including 30 males and 14 females, with an age of (58.3±11.5) years old. Twenty healthy people (20 eyes) were included as control group. Slit-lamp microscopy was performed to observe the corneal ulcer. According to the diameter of corneal ulcer, patients were divided into mild, moderate and severe groups. With in vivo confocal microscopic ,the images were obtained from the epithelial layer to the endothelial layer in the central cornea and superior, inferior, nasal and temporal peripheral cornea. Parameters of the maximum density of fungal hyphae, the maximum depth of hyphal infiltration, the density, area and length of dendritic cells (DCs), the nerve density, and the number and curvature of nerve trunks were collected. The Kruskal-Wallis test, Wilcoxon test, and Spearman correlation analysis were used for analyses. Results: On confocal microscopy, many uniform, highly reflective, segment-like structures in parallel or staggered rows were detected in the cornea, with a certain degree of physiological curvature and branching. Quantitative analysis of hyphal density found that the median rating of hyphal density was 2.6 (2.0, 3.0), mainly with medium to large amounts of hyphae. Most hyphae were 100-150 μm in depth (18 cases, 40.9%), and the maximum depth of hyphae in 95.5% (42 cases) of patients was within 300 μm. The hyphal invasion depth in the mild group was 89.4 (50.5, 106.8) μm, in the moderate group was 133 (122, 203) μm, and in the severe group was 135 (74, 151) μm. As the severity of the disease increased, the depth of hyphal invasion increased (F=4.248, P=0.001). Compared with the control group, the DC density [166 (81.3, 212.5) vs. 24.0 (20.8, 32.3) cells/μm²], area [441.3 (291.9, 529.5) vs. 63.7 (47.7, 70.3) μm²] and length [68.3 (39.4, 91.0) vs. 9.2 (7.0, 11.3) μm] increased in patients (W=493.5, 500.0, 500.0; P<0.01). The nerve density [5 398.3 (3 202.7, 6 828.3) vs. 19 171.8 (17 558.8, 21 550.4) μm/mm²; t=-14.448, P<0.01] and the length [692.7 (402.0, 925.1) vs.2 138.4 (1 940.4, 2 597.2) μm; t=-11.930, P<0.01] and number [2.9 (2.0,3.0) vs. 6.0 (5.5,7.0); t=-8.282, P<0.01] of nerve trunks in patients decreased. There were strong negative correlations between the nerve density, the number of nerve trunks, and the DC density (r=-0.555, -0.466; P<0.01). Conclusions: The depth of fungal hypha invasion in patients with fungal keratitis is mainly concentrated in the epithelial layer and superficial stroma layer. The density of mature dendritic cells in the lesion area was negatively correlated with the density and number of subbasal nerves. The density of subbasal nerves decreased as the increase of the severity of the lesion. (Chin J Ophthalmol, 2021, 57: 580-588).

Transcriptome-Wide Identification of G-to-A RNA Editing in Chronic Social Defeat Stress Mouse Models

Emerging evidence suggests that RNA editing is associated with stress, neurological diseases, and psychiatric disorders. However, the role of G-to-A RNA editing in chronic social defeat stress (CSDS) remains unclear. We herein identified G-to-A RNA editing and its changes in the ventral tegmental area (VTA), a key region of the brain reward system, in CSDS mouse models under emotional stress (ES) and physiological stress (PS) conditions. Our results revealed 3812 high-confidence G-to-A editing events. Among them, 56 events were significantly downregulated while 23 significantly upregulated in CSDS compared to controls. Moreover, divergent editing patterns were observed between CSDS mice under ES and PS conditions, with 42 and 21 events significantly upregulated in PS and ES, respectively. Interestingly, differential RNA editing was enriched in genes with multiple editing events. Genes differentially edited in CSDS included those genetically associated with mental or neurodevelopmental disorders, especially mood disorders, such as FAT atypical cadherin 1 and solute carrier family 6 member 1. Notably, changes of G-to-A RNA editing were also implicated in ionotropic glutamate receptors, a group of well-known targets of adenosine-to-inosine RNA editing. Such results demonstrate dynamic G-to-A RNA editing changes in the brain of CSDS mouse models, underlining its role as a potential molecular mechanism of CSDS and stress-related diseases.

[Progress of clinical diagnosis and treatment in fungal keratitis]

Fungal keratitis is an important cause of corneal blindness in China. Delayed diagnosis and treatment contribute to its poor prognosis. In recent years, with the advancement of laboratory test techniques, imaging diagnostic techniques and treatment methods, the diagnosis and treatment of fungal keratitis has constantly improved. This article reviews the recent progress of the laboratory and imaging diagnosis, medicine and surgical treatment in fungal keratitis. It may be helpful to promote the application of the new technologies in China and to improve the prognosis of fungal keratitis.(Chin J Ophthalmol, 2020, 56: 631-636).

[Mechanism of transcriptional regulation of Meox1 by transforming growth factor β (1) and its effect on cell migration of adult human dermal fibroblasts]

Objective: To explore the transcriptional regulation mechanism of transforming growth factor β(1) (TGF-β(1)) on Meox1 and its effect on cell migration of adult human dermal fibroblasts (HDF-a). Methods: (1) HDF-a cells were cultured in RPMI 1640 complete medium (hereinafter referred to as routinely cultured). The cells were divided into TGF-β(1) stimulation group and blank control group. The cells in TGF-β(1) stimulation group were stimulated with 10 μL TGF-β(1) in the mass concentration of 1 mg/μL, while the cells in blank control group were stimulated with the equal volume of phosphate buffer solution. After 72 hours in culture, partial cells in both groups were collected for transcriptome sequencing. The genes with differential expression ratio greater than or equal to 2 and P<0.01 between the two groups were selected to perform enrichment analysis and analysis of metabolic pathways of the Kyoto Gene and Genome Encyclopedia with, and the expression value of Meox1 per million transcripts (TPM) was recorded (n=3). Partial cells from the two groups were used to detect the Meox1 mRNA expression by real-time fluorescent quantitative reverse transcription polymerase chain reaction (RT-PCR) (n=3). (2) Cultured HDF-a cells in the logarithmic growth phase (the same growth phase of cells below) were divided into empty plasmid group, Smad2 overexpression (OE) group, Smad3 OE group, and Smad4 OE group, which were transfected respectively with 2 μg empty pcDNA3.1 plasmid and pcDNA3.1 plasmids separately carrying Smad2, Smad3, and Smad4 for 6 hours, and then were routinely cultured for 48 hours. The Meox1 mRNA expression in the transfected cells of each group was detected by real-time fluorescent quantitative RT-PCR (n=3). (3) HDF-a cells were routinely cultured and grouped the same as in experiment (1). After 72 hours in culture, the enrichment of Smad2, Smad3, and Smad4 protein on the Meox1 promoter in the cells of each group was detected by chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) (n=3). (4) HDF-a cells were routinely cultured and divided into negative interference group, small interference RNA (siRNA)-Smad2 group, siRNA-Smad3 group, siRNA-Smad4 group, empty plasmid group, Smad2 OE group, Smad3 OE group, and Smad4 OE group, which were transfected respectively with 50 μmol/L random siRNA, siRNA-Smad2, siRNA-Smad3, siRNA-Smad4, 2 μg empty pcDNA3.1 plasmid and pcDNA3.1 plasmids separately carrying Smad2, Smad3, and Smad4 for 6 hours and then routinely cultured for 48 hours. The enrichment of Smad2, Smad3, and Smad4 protein on the Meox1 promoter in the cells of corresponding group was detected by ChIP-qPCR (n=3). (5) Two batches of HDF-a cells were cultured and divided into negative interference group, siRNA-Meox1 group, empty plasmid group, and Meox1 OE group, which were transfected respectively with 50 μmol/L random siRNA, siRNA-Meox1, 2 μg empty pcDNA3.1 plasmid and pcDNA3.1 plasmid carrying Meox1 for 6 hours and then routinely cultured for 24 hours. One batch of cells were subjected to scratch test with the scratch width being observed 24 hours after scratching and compared with the initial width for scratch wound healing; the other batch of cells were subjected to Transwell assay, in which the migrated cells were counted after being routinely cultured for 24 hours (n=3). (6) From January 2018 to June 2019, 3 hypertrophic scar patients (2 males and 1 female, aged 35-56 years) were admitted to the First Affiliated Hospital of Army Medical University (the Third Military Medical University) 8-12 months after burns. The scar tissue and normal skin tissue along the scar margin resected during surgery were taken, and immunohistochemical staining was performed to observe the distribution of Meox1 protein expression. Data were statistically analyzed with one-way analysis of variance and independent sample t test. Results: (1) After 72 hours in culture, a total of 843 genes were obviously differentially expressed between the two groups, being related to tissue repair, cell migration, inflammatory cell chemotaxis induction process and potential signaling pathways such as tumor necrosis factor, interleukin 17, extracellular matrix receptor. The TPM value of Meox1 in the cells of blank control group was 45.9±1.9, which was significantly lower than 163.1±29.5 of TGF-β(1) stimulation group (t=6.88, P<0.01) with RNA-sequencing. After 72 hours in culture, the Meox1 mRNA expression levels in the cells of blank control group was 1.00±0.21, which was significantly lower than 11.00±3.61 of TGF-β(1) stimulation group (t=4.79, P<0.01). (2) After 48 hours in culture, the Meox1 mRNA expression levels in the cells of Smad2 OE group, Smad3 OE group, and Smad4 OE group were 198.70±11.02, 35.47±4.30, 20.27±2.50, respectively, which were significantly higher than 1.03±0.19 of empty plasmid group (t=31.07, 13.80, 13.12, P<0.01). (3) After 72 hours in culture, the enrichment of Smad2, Smad3, and Smad4 protein on the promoter of Meox1 in the cells of TGF-β(1) stimulation group was significantly higher than that of blank control group respectively (t=12.99, 41.47, 29.10, P<0.01). (4) After 48 hours in culture, the enrichment of Smad2 protein on the promoter of Meox1 in the cells of negative interference group was (0.200 000±0.030 000)%, significantly higher than (0.000 770±0.000 013)% of siRNA-Smad2 group (t=11.67, P<0.01); the enrichment of Smad2 protein on the promoter of Meox1 in the cells of empty plasmid group was (0.200 000±0.040 000)%, significantly lower than (0.700 000±0.090 000)% of Smad2 OE group (t=8.85, P<0.01). The enrichment of Smad3 protein on the promoter of Meox1 in the cells of negative interference group was (0.500 0±0.041 3)%, significantly higher than (0.006 0±0.001 3)% of siRNA-Smad3 group (t=17.79, P<0.01); the enrichment of Smad3 protein on the promoter of Meox1 in the cells of empty plasmid group was (0.470 0±0.080 0)%, which was significantly lower than (1.100 0±0.070 0)% of Smad3 OE group (t=9.93, P<0.01). The enrichment of Smad4 protein on the promoter of Meox1 in the cells of negative interference group was similar to that of siRNA-Smad4 group (t=2.11, P>0.05); the enrichment of Smad4 protein on the promoter of Meox1 in the cells of empty plasmid group was similar to that of Smad4 OE group (t=0.60, P>0.05). (5) Twenty-four hours after scratching, the scratch healing width of cells in siRNA-Meox1 group was narrower than that of negative interference group, while that of Meox1 OE group was wider than that of empty plasmid group. After 24 hours in culture, the number of migration cells in negative interference group was significantly higher than that in siRNA-Meox1 group (t=9.12, P<0.01), and that in empty plasmid group was significantly lower than that in Meox1 OE group (t=8.99, P<0.01). (6) The expression of Meox1 protein in the scar tissue was significantly higher than that in normal skin of patients with hypertrophic scars. Conclusions: TGF-β(1) transcriptionally regulates Meox1 expression via Smad2/3 in HDF-a cells, thus promoting cell migration.

Synthesis of high quality silver nanowires and their applications in ultrafast photonics

Silver nanowires are widely used in catalysts, surface enhanced Raman scattering, microelectronic equipment, thin film solar cells, microelectrodes and biosensors for their excellent conductivity, heat transfer, low surface resistance, high transparency and good biocompatibility. However, the optical nonlinearity of silver nanowires has not been further explored yet. In this paper, three silver nanowire samples with different concentrations are produced via a typical hydrothermal method. Their applications to fiber lasers are implemented to prove the optical nonlinearity of silver nanowires for the first time. Based on three kinds of silver nanowires, the mode-locked operation of fiber lasers is successfully realized. Moreover, the fiber laser based on the silver nanowire with a concentration of 2 mg/L demonstrates the shortest pulse duration of 149.3 fs. The experiment not only proves the optical nonlinearity of silver nanowires, but also has some enlightenment on the selection of the optimum concentration of silver nanowires in the consideration of ultrashort pulse output.

BODIPY-Decorated Nanoscale Covalent Organic Frameworks for Photodynamic Therapy

Covalent organic frameworks (COFs), an emerging class of organic porous materials, have attracted intense attention due to their versatile applications. However, the deliberate fabrication of COF-based nanomaterials for nanomedical application remains challenging due to difficulty in their size- and structure-controlled synthesis and poor aqueous dispersibility. Herein, we report two boron-dipyrromethene (BODIPY)-decorated nanoscale COFs (NCOFs), which were prepared by the Schiff-base condensation of the free end -CHO (bonding defects in COFs) on the established imine-based NCOFs with the amino-substituted organic photosensitizer BODIPY via "bonding defects functionalization" approach. Thus BODIPY has been successfully nanocrystallized via the NCOF platform, and can be used for photodynamic therapy (PDT) to treat tumors. These NCOF-based PDT agents featured nanometer size (∼110 nm), low dark toxicity, and high phototoxicity as evidenced by in vitro and in vivo experiments. Moreover, the "bonding defects functionalization" approach might open up new avenues for the fabrication of additional COF-based platforms for biomedical treatment.

Nonlinear optical properties of MoS2-WS2 heterostructure in fiber lasers

As a saturable absorption material, the heterostructure with the van der Waals structure has been paid much attention in material science. In general, the heterogeneous combination is able to neutralize, or even exceed, the individual material's advantages in some aspects. In this paper, which describes the magnetron sputtering deposition method, the tapered fiber is coated by the MoS₂-WS₂ heterostructure, and the MoS₂-WS₂ heterostructure saturable absorber (SA) is fabricated. The modulation depth of the prepared MoS₂-WS₂ heterostructure SA is measured to be 19.12%. Besides, the theoretical calculations for the band gap and carrier mobility of the MoS₂-WS₂ heterostructure are provided. By employing the prepared SA, a stable and passively erbium-doped fiber laser is implemented. The generated pulse duration of 154 fs is certified to be the shortest among all fiber lasers based on transition mental dichalcogenides. Results in this paper provide the new direction for the fabrication of ultrafast photon modulation devices.

Effects of fat-to-sugar ratio in excess dietary energy on lipid abnormalities: a 7-month prospective feeding study in adult cynomolgus monkeys

BACKGROUND

Excess energy intake contributes to metabolic disorders. However, the relationship between excess sugar and fat in their contributions to metabolic abnormalities remains to be further elucidated. Here we conducted a prospective feeding experiment to evaluate effects of dietary fat-to-sugar ratio on diet-induced metabolic abnormalities in adult cynomolgus monkeys.

METHODS

Four groups of adult cynomolgus monkeys were fed regular chow plus emulsion with combinations of high sugar (HS) or low sugar (HS) and low fat (LF) or high fat (HF) for 7 months. Plasma levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG) and blood glucose were measured for all the four groups of animals during the experiment.

RESULTS

Plasma levels of TC and LDL-C gradually increased in all 4 diets groups, with the highest increase found in the LSHF group compared to the other three groups (P = 0.0018 and P = 0.0005 respectively). HF induced increased fasting glucose (P = 0.0077) and HS induced higher TG (P = 0.0227) respectively. Intriguingly, HSHF led to dramatically smaller magnitude of increase in LDL-C and TC levels compared to LSHF, while such difference was absent between the LSLF and LSHF groups. Our findings thus indicate interactive effects of HS and HF on TC and LDL-C. In addition, HF exhibited stronger effects on lipid abnormalities than HS.

CONCLUSIONS

In the current study, our prospective feeding experiment in adult cynomolgus monkeys revealed effects of different fat-to-sugar ratios on diet-induced metabolic abnormalities. Furthermore, our findings suggest that not only excess dietary energy but also the balance of dietary fat-to-sugar ratio matters in diet-induced lipid abnormalities.

Methylmercury-l-Cysteine targeting L-type amino acid transporter conjugate cytotoxicity on C6 glioma cells

Glioma is the most common primary tumor in the brain, accounting for about 40~50% of intracranial primary tumors. Most chemotherapeutic drugs have difficulty in penetrating the blood-brain barrier, and their clinical applications are greatly limited. We evaluated the effects of methylmercury-L-cysteine (MeHg-L-cys) and methylmercury chloride (MMC) on apoptosis of C6 glioma cells. L-type amino acid transporter (LAT1) was used to investigate the targeted transport function and cytotoxicity of MeHg- L-cys in glioma. MeHg-L-cys enhanced the ability of targeting glioma cells and reduced the adverse reactions to normal brain tissues. Therefore, it is significantly important to develop new anti-glioma drugs targeting the blood-brain barrier.

Directly Measuring the Degree of Quantum Coherence using Interference Fringes

Quantum coherence is the most distinguished feature of quantum mechanics. It lies at the heart of the quantum-information technologies as the fundamental resource and is also related to other quantum resources, including entanglement. It plays a critical role in various fields, even in biology. Nevertheless, the rigorous and systematic resource-theoretic framework of coherence has just been developed recently, and several coherence measures are proposed. Experimentally, the usual method to measure coherence is to perform state tomography and use mathematical expressions. Here, we alternatively develop a method to measure coherence directly using its most essential behavior-the interference fringes. The ancilla states are mixed into the target state with various ratios, and the minimal ratio that makes the interference fringes of the "mixed state" vanish is taken as the quantity of coherence. We also use the witness observable to witness coherence, and the optimal witness constitutes another direct method to measure coherence. For comparison, we perform tomography and calculate l_{1} norm of coherence, which coincides with the results of the other two methods in our situation. Our methods are explicit and robust, providing a nice alternative to the tomographic technique.

Generation of quasi-monoenergetic electron beams with small normalized divergences angle from a 2 TW laser facility

We report the generation of a 6 pC, 23 MeV electron bunch with the energy spread ± 3.5% by using 2 TW, 80 fs high contrast laser pulses interacting with helium gas targets. Within the optimized experimental condition, we obtained quasi-monoenergetic electron beam with an ultra-small normalized divergence angle of 92 mrad, which is at least 5 times smaller than the previous LPA-produced bunches. We suggest the significant decrease of the normalized divergence angles is due to smooth transfer from SM-LWFA to LWFA. Since the beam size in LPA is typically small, this observation may explore a simple way to generate ultralow normalized emittance electron bunches by using small-power but high-repetition-rate laser facilities.

Note: A new angle-resolved proton energy spectrometer

In typical laser-driven proton acceleration experiments Thomson parabola proton spectrometers are used to measure the proton spectra with very small acceptance angle in specific directions. Stacks composed of CR-39 nuclear track detectors, imaging plates, or radiochromic films are used to measure the angular distributions of the proton beams, respectively. In this paper, a new proton spectrometer, which can measure the spectra and angular distributions simultaneously, has been designed. Proton acceleration experiments performed on the Xtreme light III laser system demonstrates that the spectrometer can give angle-resolved spectra with a large acceptance angle. This will be conductive to revealing the acceleration mechanisms, optimization, and applications of laser-driven proton beams.

Geometric mechanics of periodic pleated origami

Origami structures are mechanical metamaterials with properties that arise almost exclusively from the geometry of the constituent folds and the constraint of piecewise isometric deformations. Here we characterize the geometry and planar and nonplanar effective elastic response of a simple periodically folded Miura-ori structure, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, defined completely by two angles and two lengths. We show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign, independent of material properties. Furthermore, we show that effective bending stiffness of the unit cell is singular, allowing us to characterize the two-dimensional deformation of a plate in terms of a one-dimensional theory. Finally, we solve the inverse design problem of determining the geometric parameters for the optimal geometric and mechanical response of these extreme structures.

Spectrally peaked electron beams produced via surface guiding and acceleration in femtosecond laser-solid interactions

Highly collimated MeV electron beam guiding has been observed along the target surface following the interaction of bulk target irradiation by femtosecond laser pulses at relativistic intensities. The beam quality is shown to depend critically on the laser contrast: With a ns prepulse, the generated electron beam is well concentrated and intense, while a high laser contrast produces divergent electron beams. In the case of large preplasma scale lengths, tunable guiding and acceleration of the target surface electrons is achieved by changing the laser incident angle. By expanding the preplasma scale length to several hundred micrometers, we obtained MeV spectrum-peaked electron beams with a 100 pC per laser pulse and divergence angles of only 3°. This technique suggests a stable method of injection of elections into a variety of accelerator designs.

Note: Diagnosing femtosecond laser-solid interactions with monochromatic Kα imager and x-ray pinhole camera

An x-ray pinhole camera and a monochromatic K(α) imager are used to measure the interactions of intense femtosecond laser pulses with Cu foil targets. The two diagnostics give different features in the spot size and the laser energy scaling, which are resulted from different physical processes. Under our experimental conditions, the K(α) emission is mainly excited by the fast electrons transporting inside the cold bulk target. In contrast, the x-ray pinhole signals are dominated by the broadband thermal x-ray emission from the hot plasma at the front target surface.

Effect of prepulse on fast electron lateral transport at the target surface irradiated by intense femtosecond laser pulses

The effects of preplasma on lateral fast electron transport at front target surface, irradiated by ultraintense (>10(18) W/cm2) laser pulses, are investigated by Kα imaging technique. A large annular Kα halo with a diameter of ∼560 μm surrounding a central spot is observed. A specially designed steplike target is used to identify the possible mechanisms. It is believed that the halos are mainly generated by the lateral diffusion of fast electrons due to the electrostatic and magnetic fields in the preplasma. This is illustrated by simulated electron trajectories using a numerical model.

Intense high-contrast femtosecond K-shell x-ray source from laser-driven Ar clusters

Bright Ar quasimonochromatic K-shell x ray with very little background has been generated using an Ar clustering gas jet target irradiated with a 30 fs ultrahigh-contrast laser, with a measured flux of 2.2×10(11)   photons/J into 4π. This intense x-ray source critically depends on the laser contrast and intensity. The optimization of source output with interaction length is addressed. Simulations point to a nonlinear resonant mechanism of electron heating during the early stage of laser interaction, resulting in enhanced x-ray emission. The x-ray pulse duration is expected to be only 10 fs, opening the possibility for single-shot ultrafast keV x-ray imaging applications.

Effective fast electron acceleration along the target surface

The dependence of angular distributions of fast electrons generated in the interaction of p-polarized femtosecond laser pulses with foil targets on laser intensities is investigated. A novel fast electron beam along the front target surface is observed for high laser intensity. It is found that the electron acceleration along the target surface is more efficient than those in other directions.

Effect of target shape on fast electron emission in femtosecond laser-plasma interactions

Fast electron emission from the interaction of femtosecond laser pulses with shaped solid targets has been studied. It is found that the angular distributions of the forward fast electrons are highly dependent upon the target shapes. The important roles played by the electrostatic fields built up at the non-laser-irradiated target surfaces and the collisions in the target are identified. Our two-dimensional particle-in-cell simulations with binary collisions included reproduce the main experimental observations.

Observation of a fast electron beam emitted along the surface of a target irradiated by intense femtosecond laser pulses

A novel fast electron beam emitting along the surface of a target irradiated by intense laser pulses is observed. The beam is found to appear only when the plasma density scale length is small. Numerical simulations reveal that the electron beam is formed due to the confinement of the surface quasistatic electromagnetic fields. The results are of interest for potential applications of fast electron beams and deep understanding of the cone-target physics in the fast ignition related experiments.

Surface topography and its transition of nematic elastomers due to photoinduced deformation

Due to the disruption of liquid-crystal order caused by photoisomerization of the rodlike molecules, solids containing light-sensitive molecules such as nematic liquid-crystal elastomers can undergo large reversible shape changes when stimulated by light. In this paper, we study surface deformation of such solids illuminated by light based on a phenomenological model. Numerical computation shows that the deformation topography of the surface depends remarkably on the spot radius of light. The result is expected helpful to practical applications related to the creation of surface patterns, such as guidance of microfluids and manipulation of nanostructures.

Control of filamentation induced by femtosecond laser pulses propagating in air

Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated. It is found that the position of filamentation can be controlled continuously by changing the laser power and divergence angle of the laser beam. An analytical model for the process is given.

Third-order harmonic generation by self-guided femtosecond pulses in air

Strong third-order harmonic (TH) emission is observed with a conversion efficiency higher than 10(-3) from a plasma channel formed by self-guided femtosecond laser pulses propagating in air. The main characteristics of TH emission in various conditions and the phase-matching condition between the fundamental and the TH wave are investigated. An optimized condition is found, under which the TH conversion efficiency is maximized. Our experimental results show that radiation of the emission in ultraviolet wavelength range makes a major attribution to TH emission, whereas the effects of self-phase modulation are not important when intense laser pulses interact with gaseous media.

Long plasma channels generated by femtosecond laser pulses

Generation of a long plasma channel by femtosecond laser pulses is investigated. The results show that the balance between the nonlinear self-focusing of the laser beam and plasma defocusing forms a long plasma channel, which guides the laser beam to propagate a long distance in air. This phenomenon can be used to trigger lightning.

Effects of laser polarization on jet emission of fast electrons in femtosecond-laser plasmas

Effects of laser polarization on fast electron emission are studied from an aluminum target irradiated by ultrashort laser pulses at 2 x 10(16) W/cm(2). Jet emission of outgoing fast electrons collimated in the polarization direction is observed for s-polarized laser irradiation, whereas for p-polarized irradiation highly directional emission of outgoing fast electrons is found in the direction close to the normal of the target. The behavior of ingoing fast electrons into the target for s- and p-polarized irradiation is also investigated by observing x-ray bremsstrahlung radiation at the backside of the target.

Hot electrons in the interaction of femtosecond laser pulses with foil targets at a moderate laser intensity

Characteristics of hot electrons produced in the interaction of femtosecond laser pulses with foil targets were investigated at a moderate laser intensity. Both outgoing and ingoing hot electrons from the femtosecond laser plasma were studied. A collimated jet of outgoing hot electrons was observed in the target normal direction. An ingoing energetic hot-electron beam was found in the laser propagation direction, while the low-energy ingoing electrons spread into wider cone angle due to the collisional effects in the plasma and target material. These observations were supported by three-dimensional Monte Carlo simulations. The hot-electron temperature obtained from electron spectra and absorption experiments implies that resonance absorption is partially responsible for the generation of hot electrons.