High Potency of a Bivalent Human VH Domain in SARS-CoV-2 Animal Models.

Novel COVID-19 therapeutics are urgently needed. We generated a phage-displayed human antibody VH domain library from which we identified a high-affinity VH binder ab8. Bivalent VH, VH-Fc ab8, bound with high avidity to membrane-associated S glycoprotein and to mutants found in patients. It potently neutralized mouse-adapted SARS-CoV-2 in wild-type mice at a dose as low as 2 mg/kg and exhibited high prophylactic and therapeutic efficacy in a hamster model of SARS-CoV-2 infection, possibly enhanced by its relatively small size. Electron microscopy combined with scanning mutagenesis identified ab8 interactions with all three S protomers and showed how ab8 neutralized the virus by directly interfering with ACE2 binding. VH-Fc ab8 did not aggregate and did not bind to 5,300 human membrane-associated proteins. The potent neutralization activity of VH-Fc ab8 combined with good developability properties and cross-reactivity to SARS-CoV-2 mutants provide a strong rationale for its evaluation as a COVID-19 therapeutic.

Structure of the moiré exciton captured by imaging its electron and hole.

Interlayer excitons (ILXs) - electron-hole pairs bound across two atomically thin layered semiconductors - have emerged as attractive platforms to study exciton condensation1-4, single-photon emission and other quantum information applications5-7. Yet, despite extensive optical spectroscopic investigations8-12, critical information about their size, valley configuration and the influence of the moiré potential remains unknown. Here, in a WSe2/MoS2 heterostructure, we captured images of the time-resolved and momentum-resolved distribution of both of the particles that bind to form the ILX: the electron and the hole. We thereby obtain a direct measurement of both the ILX diameter of around 5.2 nm, comparable with the moiré-unit-cell length of 6.1 nm, and the localization of its centre of mass. Surprisingly, this large ILX is found pinned to a region of only 1.8 nm diameter within the moiré cell, smaller than the size of the exciton itself. This high degree of localization of the ILX is backed by Bethe-Salpeter equation calculations and demonstrates that the ILX can be localized within small moiré unit cells. Unlike large moiré cells, these are uniform over large regions, allowing the formation of extended arrays of localized excitations for quantum technology.

The Toxoplasma protein phosphatase 6 catalytic subunit (TgPP6C) is essential for cell cycle progression and virulence.

Protein phosphatases are post-translational regulators of Toxoplasma gondii proliferation, tachyzoite-bradyzoite differentiation and pathogenesis. Here, we identify the putative protein phosphatase 6 (TgPP6) subunits of T. gondii and elucidate their role in the parasite lytic cycle. The putative catalytic subunit TgPP6C and regulatory subunit TgPP6R likely form a complex whereas the predicted structural subunit TgPP6S, with low homology to the human PP6 structural subunit, does not coassemble with TgPP6C and TgPP6R. Functional studies showed that TgPP6C and TgPP6R are essential for parasite growth and replication. The ablation of TgPP6C significantly reduced the synchronous division of the parasite's daughter cells during endodyogeny, resulting in disordered rosettes. Moreover, the six conserved motifs of TgPP6C were required for efficient endodyogeny. Phosphoproteomic analysis revealed that ablation of TgPP6C predominately altered the phosphorylation status of proteins involved in the regulation of the parasite cell cycle. Deletion of TgPP6C significantly attenuated the parasite virulence in mice. Immunization of mice with TgPP6C-deficient type I RH strain induced protective immunity against challenge with a lethal dose of RH or PYS tachyzoites and Pru cysts. Taken together, the results show that TgPP6C contributes to the cell division, replication and pathogenicity in T. gondii.

Unidirectional Transmission Metasurfaces with Topological Continuity Generated from High-dimensional Design Space.

With the growing demand for nanodevices, there is a concerted effort to improve the design flexibility of nanostructures, thereby expanding the capabilities of nanophotonic devices. In this work, a Laplacian-weighted binary search (LBS) algorithm is proposed to generate a unidirectional transmission metasurface from a high-dimensional design space, offering an increased degree of design freedom. The LBS algorithm incorporates topological continuity based on the Laplacian, effectively circumventing the common issue of high structural complexity in designing high-dimensional nanostructures. As a result, metasurfaces developed using the LBS algorithm in a high-dimensional design space exhibit reduced complexity, which is advantageous for experimental fabrication. An all-dielectric metasurface with unidirectional transmission, designed from the high-dimensional space using the LBS method, demonstrated the successful application of these design principles in experiments. The metasurface exhibits high optical performance on unidirectional transmission in measurements by a high-resolution angle-resolved micro-spectra system, achieving forward transmissivity above 90% (400-700 nm) and back transmissivity below 20% (400-500 nm) within the targeted wavelength range. This work provides a feasible approach for advancing high-dimensional metasurface applications, as the LBS design method takes into account topological continuity during experimental processing. Compared to traditional direct binary search (DBS) methods, the LBS method not only improves information processing efficiency but also maintains the topological continuity of structures. Beyond unidirectional transmission, the LBS-based design method has generality and flexibility to accommodate almost all physical scenarios in metasurface design, enabling a multitude of complex functions and applications.

A novel recombinant S-based subunit vaccine induces protective immunity against porcine deltacoronavirus challenge in piglets.

IMPORTANCE: As an emerging porcine enteropathogenic coronavirus that has the potential to infect humans, porcine deltacoronavirus (PDCoV) is receiving increasing attention. However, no effective commercially available vaccines against this virus are available. In this work, we designed a spike (S) protein and receptor-binding domain (RBD) trimer as a candidate PDCoV subunit vaccine. We demonstrated that S protein induced more robust humoral and cellular immune responses than the RBD trimer in mice. Furthermore, the protective efficacy of the S protein was compared with that of inactivated PDCoV vaccines in piglets and sows. Of note, the immunized piglets and suckling pig showed a high level of NAbs and were associated with reduced virus shedding and mild diarrhea, and the high level of NAbs was maintained for at least 4 months. Importantly, we demonstrated that S protein-based subunit vaccines conferred significant protection against PDCoV infection.

Dense Polarized Positrons from Beam-Solid Interaction.

Relativistic positron sources with high spin polarization have important applications in nuclear and particle physics and many frontier fields. However, it is challenging to produce dense polarized positrons. Here we present a simple and effective method to achieve such a positron source by directly impinging a relativistic high-density electron beam on the surface of a solid target. During the interaction, a strong return current of plasma electrons is induced and subsequently asymmetric quasistatic magnetic fields as high as megatesla are generated along the target surface. This gives rise to strong radiative spin flips and multiphoton processes, thus leading to efficient generation of copious polarized positrons. With three-dimensional particle-in-cell simulations, we demonstrate the production of a dense highly polarized multi-GeV positron beam with an average spin polarization above 40% and nC-scale charge per shot. This offers a novel route for the studies of laserless strong-field quantum electrodynamics physics and for the development of high-energy polarized positron sources.

The antioxidant protein glutaredoxin 1 is essential for oxidative stress response and pathogenicity of Toxoplasma gondii.

Glutaredoxins (Grxs) are ubiquitous antioxidant proteins involved in many molecular processes to protect cells against oxidative damage. Here, we study the roles of Grxs in the pathogenicity of Toxoplasma gondii. We show that Grxs are localized in the mitochondria (Grx1), cytoplasm (Grx2), and apicoplast (Grx3, Grx4), while Grx5 had an undetectable level of expression. We generated Δgrx1-5 mutants of T. gondii type I RH and type II Pru strains using CRISPR-Cas9 system. No significant differences in the infectivity were detected between four Δgrx (grx2-grx5) strains and their respective wild-type (WT) strains in vitro or in vivo. Additionally, no differences were detected in the production of reactive oxygen species, total antioxidant capacity, superoxide dismutase activity, and sensitivity to external oxidative stimuli. Interestingly, RHΔgrx1 or PruΔgrx1 exhibited significant differences in all the investigated aspects compared to the other grx2-grx5 mutant and WT strains. Transcriptome analysis suggests that deletion of grx1 altered the expression of genes involved in transport and metabolic pathways, signal transduction, translation, and obsolete oxidation-reduction process. The data support the conclusion that grx1 supports T. gondii resistance to oxidative killing and is essential for the parasite growth in cultured cells and pathogenicity in mice and that the active site CGFS motif was necessary for Grx1 activity.

Cryo-electron microscopy structures of the N501Y SARS-CoV-2 spike protein in complex with ACE2 and 2 potent neutralizing antibodies.

The recently reported "UK variant" (B.1.1.7) of SARS-CoV-2 is thought to be more infectious than previously circulating strains as a result of several changes, including the N501Y mutation. We present a 2.9-Å resolution cryo-electron microscopy (cryo-EM) structure of the complex between the ACE2 receptor and N501Y spike protein ectodomains that shows Y501 inserted into a cavity at the binding interface near Y41 of ACE2. This additional interaction provides a structural explanation for the increased ACE2 affinity of the N501Y mutant, and likely contributes to its increased infectivity. However, this mutation does not result in large structural changes, enabling important neutralization epitopes to be retained in the spike receptor binding domain. We confirmed this through biophysical assays and by determining cryo-EM structures of spike protein ectodomains bound to 2 representative potent neutralizing antibody fragments.

Photo-induced C(sp2)-H difluoroalkylation of anilines.

A photoinduced protocol for the direct difluoroalkylation of C(sp2)-H bonds in anilines under catalyst-free reaction conditions is presented. This transformation is characterized by a wide substrate scope, mild reaction conditions, and operational simplicity, and could serve as an alternative tool to established methods for the synthesis of difluoroalkylated anilines. Mechanistic studies suggest the formation of an electron-donor-acceptor (EDA) complex between anilines and difluoroalkyl bromides in this reaction.

Pulmonary embolism in patients with chronic coronary syndrome masquerading as acute coronary syndrome: a case report and literature review.

BACKGROUND: Pulmonary embolisms (PEs) exhibit clinical features similar to those of acute coronary syndrome (ACS), including electrocardiographic abnormalities and elevated troponin levels, which frequently lead to misdiagnoses in emergency situations. CASE PRESENTATION: Here, we report a case of PE coinciding with chronic coronary syndrome in which the patient's condition was obscured by symptoms mimicking ACS. A 68-year-old female with syncope presented to the hospital. Upon admission, she was found to have elevated troponin levels and an electrocardiogram showing ST-segment changes across multiple leads, which initially led to a diagnosis of ACS. Emergency coronary arteriography revealed occlusion of the posterior branches of the left ventricle of the right coronary artery, but based on the complexity of the intervention, the occlusion was considered chronic rather than acute. On the 3rd day after admission, the patient experienced recurrent chest tightness and shortness of breath, which was confirmed as acute PE by emergency computed tomography pulmonary angiography. Following standardized anticoagulation treatment, the patient improved and was subsequently discharged. CONCLUSIONS: This case report highlights the importance of recognizing the nonspecific features of PE. Clinicians should be vigilant when identifying other clinical features that are difficult to explain accompanying the expected disease, and it is necessary to carefully identify the causes to prevent missed diagnoses or misdiagnoses.

Csi-let-7a-5p delivered by extracellular vesicles from a liver fluke activates M1-like macrophages and exacerbates biliary injuries.

Chronic infection with liver flukes (such as Clonorchis sinensis) can induce severe biliary injuries, which can cause cholangitis, biliary fibrosis, and even cholangiocarcinoma. The release of extracellular vesicles by C. sinensis (CsEVs) is of importance in the long-distance communication between the hosts and worms. However, the biological effects of EVs from liver fluke on biliary injuries and the underlying molecular mechanisms remain poorly characterized. In the present study, we found that CsEVs induced M1-like activation. In addition, the mice that were administrated with CsEVs showed severe biliary injuries associated with remarkable activation of M1-like macrophages. We further characterized the signatures of miRNAs packaged in CsEVs and identified a miRNA Csi-let-7a-5p, which was highly enriched. Further study showed that Csi-let-7a-5p facilitated the activation of M1-like macrophages by targeting Socs1 and Clec7a; however, CsEVs with silencing Csi-let-7a-5p showed a decrease in proinflammatory responses and biliary injuries, which involved in the Socs1- and Clec7a-regulated NF-κB signaling pathway. Our study demonstrates that Csi-let-7a-5p delivered by CsEVs plays a critical role in the activation of M1-like macrophages and contributes to the biliary injuries by targeting the Socs1- and Clec7a-mediated NF-κB signaling pathway, which indicates a mechanism contributing to biliary injuries caused by fluke infection. However, molecules other than Csi-let-7a-5p from CsEVs that may also promote M1-like polarization and exacerbate biliary injuries are not excluded.

Bile Acid Injection Regulated Blood Glucose in T2DM Rats Via the TGR5/GLP-1 Rather than FXR/FGF15 Pathway.

Background and Aims: Type 2 Diabetes mellitus (T2DM) has reached an epidemic status worldwide. Targeting bile acid signaling has therapeutic potential for treating T2DM. However, the effect of bile acid on T2DM and related mechanisms remains unclear. Here, we explored the role of bile acid in T2DM and elucidated the mechanisms involved. Methods: We established an STZ-induced rat model of T2DM and divided it into an bile acid-treated group and saline control group according to the random number table method. We incubated the bile acid-treated group with human bile acid via middle small intestine intubation and the saline control group was incubated with the same amount of normal saline. We compared the fasting body mass, fasting blood glucose (FBG), 2-hour postprandial blood glucose (2h-PG), fasting plasma insulin (FINS), fasting plasma triglyceride (TG), cholesterol, and total bile acid levels between the two groups one week before surgery and one to four weeks after surgery. Mechanically, Western blot, IHC, and ELISA assays were employed to detect the effect of bile acid on the TGR5/GLP-1 and FXR/FGF15 pathways. Results: Bile acid injection could increase the FINS level and decrease the 2h-PBG level of T2DM rats. In addition, bile acid injection did not affect FBG, fasting body mass, TG, CH, and total bile acid. At the same time, bile acid injection could activate the TGR5/GLP-1 pathway but could not influence the FXR/FGF15 pathway. Conclusion: Bile acids treatment promotes glucose homeostasis in the STZ-induced T2MD rat model via the following mechanism by activating the TGR5/GLP-1 signaling pathway rather than FXR/FGF15 pathway to improve glucose tolerance and thus achieve glucose homeostasis. The bile acid/TGR5/GLP-1 signaling pathway may be a crucial mechanism of controlling the blood glucose of T2DM rats, and TGR5/GLP-1 pathway may constitute novel targets for treating T2DM.

Prevalence and genotype/subtype distribution of Enterocytozoon bieneusi and Blastocystis in donkeys in Shanxi Province, north China.

Enterocytozoon bieneusi and Blastocystis may cause diarrhea in humans and various animals. However, little information is available regarding the prevalence and genetic diversity of E. bieneusi and Blastocystis in donkeys. To fill this gap, we molecularly assessed E. bieneusi and Blastocystis in fecal samples from donkeys (n = 815) in Shanxi Province, north China. The overall prevalence of E. bieneusi and Blastocystis in donkeys was 8.1% and 0.2%, respectively. Region and age were risk factors associated with E. bieneusi infection in donkeys. Three internal transcribed spacer (ITS) genotypes of E. bieneusi were identified in the current study, including two previously described genotypes (D and Henan-IV) and one novel genotype (named SXD1). Of which, genotype D was found to be the most prevalent. Phylogenetic analysis demonstrated that the three genotypes belonged to group 1, implying a potential of zoonotic transmission. Multilocus sequence typing showed that 19, 15, 13, and 22 types were identified at the loci MS1, MS3, MS4, and MS7, respectively, forming six multilocus genotypes (MLGs) distributed in the genotype D. One Blastocystis subtype (ST33) was identified, which has previously been reported only in horses. This is the first molecular-based description of E. bieneusi and Blastocystis infections in donkeys in Shanxi Province, north China, contributing to a better understanding of transmission dynamics and molecular epidemiological characteristics of the two intestinal protozoa.

Expression profiles of host miRNAs and circRNAs and ceRNA network during Toxoplasma gondii lytic cycle.

Toxoplasma gondii is an opportunistic protozoan parasite that is highly prevalent in the human population and can lead to adverse health consequences in immunocompromised patients and pregnant women. Noncoding RNAs, such as microRNAs (miRNAs) and circular RNAs (circRNAs), play important regulatory roles in the pathogenesis of many infections. However, the differentially expressed (DE) miRNAs and circRNAs implicated in the host cell response during the lytic cycle of T. gondii are unknown. In this study, we profiled the expression of miRNAs and circRNAs in human foreskin fibroblasts (HFFs) at different time points after T. gondii infection using RNA sequencing (RNA-seq). We identified a total of 7, 7, 27, 45, 70, 148, 203, and 217 DEmiRNAs and 276, 355, 782, 1863, 1738, 6336, 1229, and 1680 DEcircRNAs at 1.5, 3, 6, 9, 12, 24, 36, and 48 h post infection (hpi), respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed that the DE transcripts were enriched in immune response, apoptosis, signal transduction, and metabolism-related pathways. These findings provide new insight into the involvement of miRNAs and circRNAs in the host response to T. gondii infection.

Functional Characterization of Six Eukaryotic Translation Initiation Factors of Toxoplasma gondii Using the CRISPR-Cas9 System.

Eukaryotic translation initiation factors (eIFs) are crucial for initiating protein translation and ensuring the correct assembly of mRNA-ribosomal subunit complexes. In this study, we investigated the effects of deleting six eIFs in the apicomplexan parasite Toxoplasma gondii using the CRISPR-Cas9 system. We determined the subcellular localization of these eIFs using C-terminal endogenous tagging and immunofluorescence analysis. Four eIFs (RH::315150-6HA, RH::286090-6HA, RH::249370-6HA, and RH::211410-6HA) were localized in the cytoplasm, while RH::224235-6HA was localized in the apicoplast. Additionally, RH::272640-6HA was found in both the basal complex and the cytoplasm of T. gondii. Functional characterization of the six RHΔeIFs strains was conducted using plaque assay, cell invasion assay, intracellular growth assay and egress assay in vitro, and virulence assay in mice. Disruption of five eIF genes (RHΔ315150, RHΔ272640, RHΔ249370, RHΔ211410, and RHΔ224235) did not affect the ability of the T. gondii RH strain to invade, replicate, form plaques and egress in vitro, or virulence in Kunming mice (p > 0.05). However, the RHΔ286090 strain showed slightly reduced invasion efficiency and virulence (p < 0.01) compared to the other five RHΔeIFs strains and the wild-type strain. The disruption of the TGGT1_286090 gene significantly impaired the ability of tachyzoites to differentiate into bradyzoites in both type I RH and type II Pru strains. These findings reveal that the eukaryotic translation initiation factor TGGT1_286090 is crucial for T. gondii bradyzoite differentiation and may serve as a potential target for drug development and an attenuated vaccine against T. gondii.

Structural and sensory characteristics of ultrasonic assisted wet-heating Maillard reaction products of Giant salamander protein hydrolysates.

BACKGROUND: Chinese giant salamander protein hydrolysates (CGSPH) are beneficial to human health as a result of their high content of amino acids and peptides. However, the formation of bitter peptides in protein hydrolysates (PHs) would hinder their application in food industry. The ultrasound assisted wet-heating Maillard reaction (MR) is an effective way to improve the flavor of PHs. Thus, the effect of ultrasonic assisted wet-heating MR on the structure and flavor of CGSPH was investigated in the present study. RESULTS: The results indicated that the ultrasound assisted wet-heating MR products (MRPs) exhibited a higher degree of graft and more significant changes in the secondary and tertiary structures of CGSPH compared to traditional wet-heating MRPs. Moreover, ultrasound assisted wet-heating MR could significantly increase the content of small molecule peptides and reduce the content of free amino acids of CGSPH, which resulted in more significant changes in flavor characteristics. The changed in flavor properties after MR (especially ultrasound assisted wet-heating MRPs) were mainly manifested by a significant reduction in bitterness, as well as a significant increase in the content of aromatic aldehyde ester compounds such as furan-2-carbaldehyde, butanal, benzaldehyde, furfural, etc. CONCLUSIONS: Ultrasound assisted wet-heating MR between CGSPH and xylose could be a promising way to improve the sensory characteristics of CGSPH. © 2024 Society of Chemical Industry.

Virtual Photon-Mediated Quantum State Transfer and Remote Entanglement between Spin Qubits in Quantum Dots Using Superadiabatic Pulses.

Spin qubits in semiconductor quantum dots are an attractive candidate for scalable quantum information processing. Reliable quantum state transfer and entanglement between spatially separated spin qubits is a highly desirable but challenging goal. Here, we propose a fast and high-fidelity quantum state transfer scheme for two spin qubits mediated by virtual microwave photons. Our general strategy involves using a superadiabatic pulse to eliminate non-adiabatic transitions, without the need for increased control complexity. We show that arbitrary quantum state transfer can be achieved with a fidelity of 95.1% within a 60 ns short time under realistic parameter conditions. We also demonstrate the robustness of this scheme to experimental imperfections and environmental noises. Furthermore, this scheme can be directly applied to the generation of a remote Bell entangled state with a fidelity as high as 97.6%. These results pave the way for fault-tolerant quantum computation on spin quantum network architecture platforms.

Effects of HMGB1/RAGE/cathespin B inhibitors on alleviating hippocampal injury by regulating microglial pyroptosis and caspase activation in neonatal hypoxic-ischemic brain damage.

Microglia play a crucial role in regulating neuroinflammation in the pathogenesis of neonatal hypoxic-ischemic brain damage (HIBD). Pyroptosis, an inflammatory form of programmed cell death, has been implicated in HIBD; however, its underlying mechanism remains unclear. We previously demonstrated that high-mobility group box 1 protein (HMGB1) mediates neuroinflammation and microglial damage in HIBD. In this study, we aimed to investigate the association between HMGB1 and microglial pyroptosis and elucidate the mechanism involved in rats with HIBD (both sexes were included) and in BV2 microglia subjected to oxygen-glucose deprivation. Our results showed that HMGB1 inhibition by glycyrrhizin (20 mg/kg) reduced the expression of microglial pyroptosis-related proteins, including caspase-1, the N-terminus fragment of gasdermin D (N-GSDMD), and pyroptosis-related inflammatory factors, such as interleukin (IL) -1ß and IL-18. Moreover, HMGB1 inhibition resulted in reduced neuronal damage in the hippocampus 72 h after HIBD and ultimately improved neurobehavior during adulthood, as evidenced by reduced escape latency and path length, as well as increased time and distance spent in the target quadrant during the Morris water maze test. These results revealed that HIBD-induced pyroptosis is mediated by HMGB1/receptor for advanced glycation end products (RAGE) signaling (inhibition by FPS-ZM1, 1 mg/kg) and the activation of cathespin B (cat B). Notably, cat B inhibition by CA074-Me (5 mg/kg) also reduced hippocampal neuronal damage by suppressing microglial pyroptosis, thereby ameliorating learning and memory impairments caused by HIBD. Lastly, we demonstrated that microglial pyroptosis may contribute to neuronal damage through the HMGB1/RAGE/cat B signaling pathway in vitro. In conclusion, these results suggest that HMGB1/RAGE/cat B inhibitors can alleviate hippocampal injury by regulating microglial pyroptosis and caspase activation in HIBD, thereby reducing the release of proinflammatory mediators that destroy hippocampal neurons and induce spatial memory impairments.

Association of dietary inflammatory index with helicobacter pylori infection and mortality among US population.

BACKGROUND: Limited research has been conducted on the potential relationship between the dietary inflammation index (DII) and mortality, particularly in individuals with Helicobacter pylori (H. pylori) infection. This study aimed to investigate the association between the DII and H. pylori infection, as well as their respective impacts on all-cause mortality in a cohort of individuals with or without H. pylori infection. METHODS: Data from the 1999-2018 National Health and Nutrition Examination Survey (NHANES) were utilized for this study, with a final of 4370 participants included. Both univariable and multivariable-adjusted logistic regression analyses were employed to explore the relationship between H. pylori infection and pertinent covariates. Cox regression analysis, as well as restricted regression cubic spline analysis, were utilized to assess the association between DII and all-cause mortality among individuals with or without H. pylori infection. RESULTS: The findings demonstrated a positive correlation between DII scores and H. pylori infection, even after adjusting for potential confounding factors. Moreover, higher DII scores were significantly associated with an elevated risk of mortality exclusively in individuals with H. pylori infection, while no such association was observed in the uninfected population. Additional analysis using restricted cubic spline modeling revealed a positive linear relationship between DII scores as a continuous variable and the adjusted risk of all-cause mortality specifically in H. pylori-infected patients. CONCLUSION: The results of this study indicated that DII was positively correlated with an increased risk of H. pylori infection and was associated with a heightened risk of all-cause mortality solely in individuals with H. pylori infection. Consequently, DII might serve as a useful tool for risk stratification in the H. pylori-infected population among U.S. adults. Further research is warranted to elucidate the underlying mechanisms and potential clinical implications of these findings.

Triangular bright solitons in nonlinear optics and Bose-Einstein condensates.

We demonstrate what we believe to be novel triangular bright solitons that can be supported by the nonlinear Schrödinger equation with inhomogeneous Kerr-like nonlinearity and external harmonic potential, which can be realized in nonlinear optics and Bose-Einstein condensates. The profiles of these solitons are quite different from the common Gaussian or sech envelope beams, as their tops and bottoms are similar to the triangle and inverted triangle functions, respectively. The self-defocusing nonlinearity gives rise to the triangle-up solitons, while the self-focusing nonlinearity supports the triangle-down solitons. Here, we restrict our attention only to the lowest-order fundamental triangular solitons. All such solitons are stable, which is demonstrated by the linear stability analysis and also clarified by direct numerical simulations. In addition, the modulated propagation of both types of triangular solitons, with the modulated parameter being the strength of nonlinearity, is also presented. We find that such propagation is strongly affected by the form of the modulation of the nonlinearity. For example, the sudden change of the modulated parameter causes instabilities in the solitons, whereas the gradual variation generates stable solitons. Also, a periodic variation of the parameter causes the regular oscillation of solitons, with the same period. Interestingly, the triangle-up and triangle-down solitons can change into each other, when the parameter changes the sign.