Spondyloarthritis and nonbacterial thrombotic endocarditis as paraneoplastic manifestations in treatment-naive Burkitt lymphoma.

Non-radiographic axial spondyloarthropathy (nr-axSpA) is a clinical diagnosis of symptoms matching inflammatory back pain criteria without radiological lesions at the sacroiliac joint. The frequency of an early nr-axSpA-like presentation in lymphoma patients has not been clarified. Here we report a woman in her 20s with a fever and musculoskeletal discomfort. Detailed investigations revealed that she was suffering from Burkitt lymphoma in which nr-axSpA-like symptoms were a musculoskeletal manifestation of the disease, irrelevant to the anti-neoplastic treatment.

Construction and validation of a m6A RNA methylation and ferroptosis-related prognostic model for pancreatic cancer by integrated bioinformatics analysis.

Background: Both N6-methyladenosine (m6A) ribonucleic acid (RNA) methylation and ferroptosis regulators are demonstrated to have significant effects on the malignant clinicopathological characteristics of pancreatic adenocarcinoma (PAAD) patients. However, the currently available clinical indexes are not sufficient to predict precise prognostic outcomes pf PAAD patients accurately. This study aims to examine the clinicopathologic features of m6A RNA methylation and ferroptosis regulators in predicting the outcomes of different types of cancer. Methods: As the foundation for this research, the differentially expressed genes (DEGs) between PAAD tissues and adjacent normal tissues were first identified. Next, dimensional reduction analysis (DCA) based on m6A RNA methylation regulators and ferroptosis regulators were performed and DEGs between good/poor prognosis PAAD patient clusters were identified. DEGs were then screened by Cox analysis, and finally a risk signature was established by least absolute shrinkage and selection operator (LASSO) analyses. The prediction model based on risk score was further evaluated by a validation set from Gene Expression Omnibus (GEO) database. Results: In total, 4 m6A RNA methylation regulator genes and 29 ferroptosis regulator genes were found to have close causal relationships with the prognosis of PAAD, and a risk score with 3 m6A methylation regulators (i.e., IGF2BP2, IGF2BP3, and METTL16) and 4 ferroptosis regulators (i.e., ENPP2, ATP6V1G2, ITGB4, and PROM2) was constructed and showed to be highly involved in PAAD progression and could serve as effective markers for prognosis with AUC value equaled 0.753 in training set and 0.803 in validation set. Conclusions: The combined prediction model, composed of seven regulators of m6A methylation and ferroptosis, in this study more effectively reflects the progression and prognosis of PAAD than previous single genome or epigenetic analysis. Our study provides a broader perspective for the subsequent establishment of prognostic models and the patients may benefit from more precision management.

Thermally reconfigurable metalens.

Reconfigurable metalenses are compact optical components composed by arrays of meta-atoms that offer unique opportunities for advanced optical systems, from microscopy to augmented reality platforms. Although poorly explored in the context of reconfigurable metalenses, thermo-optical effects in resonant silicon nanoresonators have recently emerged as a viable strategy to realize tunable meta-atoms. In this work, we report the proof-of-concept design of an ultrathin (300 nm thick) and thermo-optically reconfigurable silicon metalens operating at a fixed, visible wavelength (632 nm). Importantly, we demonstrate continuous, linear modulation of the focal-length up to 21% (from 165 µm at 20 °C to 135 µm at 260 °C). Operating under right-circularly polarized light, our metalens exhibits an average conversion efficiency of 26%, close to mechanically modulated devices, and has a diffraction-limited performance. Overall, we envision that, combined with machine-learning algorithms for further optimization of the meta-atoms, thermally reconfigurable metalenses with improved performance will be possible. Also, the generality of this approach could offer inspiration for the realization of active metasurfaces with other emerging materials within field of thermo-nanophotonics.

Achromatic metalens array for full-colour light-field imaging.

A light-field camera captures both the intensity and the direction of incoming light1-5. This enables a user to refocus pictures and afterwards reconstruct information on the depth of field. Research on light-field imaging can be divided into two components: acquisition and rendering. Microlens arrays have been used for acquisition, but obtaining broadband achromatic images with no spherical aberration remains challenging. Here, we describe a metalens array made of gallium nitride (GaN) nanoantennas6 that can be used to capture light-field information and demonstrate a full-colour light-field camera devoid of chromatic aberration. The metalens array contains an array of 60 × 60 metalenses with diameters of 21.65 µm. The camera has a diffraction-limited resolution of 1.95 µm under white light illumination. The depth of every object in the scene can be reconstructed slice by slice from a series of rendered images with different depths of focus. Full-colour, achromatic light-field cameras could find applications in a variety of fields such as robotic vision, self-driving vehicles and virtual and augmented reality.

Second Harmonic Light Manipulation with Vertical Split Ring Resonators.

The second harmonic generation (SHG) of vertical and planar split-ring resonators (SRRs) that are broken centro-symmetry configurations at the interface of metal surface and air is investigated. Strong interactions, better electromagnetic field confinements, and less leakage into the substrate for vertical SRRs are found. Experimental results show a 2.6-fold enhancement of SHG nonlinearity, which is in good agreement with simulations and calculations. Demonstrations of 3D metastructures and vertical SRRs with strong SHG nonlinearity majorly result from magnetic dipole and electric quadrupole clearly provides potential applications for photonics and sensing.

Temperature dependent structural variations of OH(-)(H2O)n, n = 4-7: effects on vibrational and photoelectron spectra.

In this work, we identified a large number of structurally distinct isomers of midsized deprotonated water clusters, OH(-)(H2O)n=4-7, using first-principles methods. The temperature dependence of the structural variation in the solvation shell of OH(-) for these clusters was examined under the harmonic superposition approximation. We simulated the vibrational and photoelectron spectra based on these thermodynamic calculations. We found that the isomers with 3-coordinated hydroxide dominate the population in these midsized clusters. Furthermore, an increase in temperature causes a topological change from compact isomers with many intermolecular hydrogen bonds to open isomers with fewer but more directional intermolecular hydrogen bonds. We showed that this evolution in structure can be observed through the change in the vibrational spectra at 3200-3400 cm(-1). In addition, the increase in directional hydrogen bonded isomers, which have outer hydration shell with OH bonds pointing to the hydroxide, causes the vertical detachment energy to increase at higher temperatures. Lastly, we also performed studies to understand the variation in the aforementioned spectral quantities with the variation in the coordination number of the hydroxide.

Site specificity on OH α-H abstraction reaction for a zwitterionic ß-hairpin peptide in aqueous solution: a theoretical investigation.

Protein backbone oxidation was investigated by studying the α-H abstraction reaction in a ß-hairpin peptide, called Chignolin (PDB ID 1UAO), with density functional theory calculation at B3LYP/6-31G(d,p) without any constraint. In order to stabilize the zwitterionic form of Chignolin with the salt bridges, the effects of aqueous solution were implemented by using microsolvation combined with a conductor-like polarizable continuum model (CPCM). Comparison between three glycine residues located at three different sites in Chignolin was used to examine the possible site specificity of this backbone oxidation. To construct the reaction profile of these α-H abstraction reactions, the pre- and postreactive complexes along with their associated transition states were located and verified with the intrinsic reaction coordinate (IRC) method. The bond dissociation energy and reaction rates of these OH α-H abstraction reactions were calculated with transition state theory. The differences in this abstraction reaction between the neutral and zwitterionic forms of Chignolin were also compared. A molecular dynamics simulation was implemented to study the explicit solvation effect on the abstracted Chignolin structure. The range of the simulation time scale covers from femtoseconds to microseconds, i.e., from onset of the abstraction to the abstracted products reaching thermal equilibrium. Our results show that there are three kinds of site-specificity in this abstraction reaction. The reactivity and stability of the abstraction products and their abstraction modes are all dependent on the location where OH attacks. Furthermore, the free energy landscapes of these abstraction products are distinctively different. This may imply that the pathological disorders or diseases caused by this type of radicals are also dependent on the abstraction location.

Site specificity of OH α-H abstraction reaction for a ß-hairpin peptide: an ab initio study.

A ß-hairpin peptide (PDB ID 1UAO) was modeled to explore the backbone oxidation of a protein by an OH radical to abstract one α-H atom with ab initio calculation at the B3LYB/6-31G(d) without any constraint. Three glycine residues located at three different sites in 1UAO were used to examine the possible site specificity of this backbone oxidation. The pre- and post-reactive complexes along with their associated transition states were located and verified by the intrinsic reaction coordinate method. The reaction profile of these α-H abstraction reactions was constructed. The effects of the aqueous solution were estimated by the conductor-like polarizable continuum model (CPCM) model. Rate constants were calculated with transition state theory. The reaction rate of the OH α-H abstraction varies among these three different sites. The differences among these three sites were rationalized in terms of the molecular and electronic structures of the reactive complexes along the reaction pathway. The explicit solvation effect was estimated through the similar abstraction of a zwitterionic glycine with the combination of microsolvation and a CPCM model. Our results indicate that the α-H abstraction at certain sites requires explicit salvation to obtain accurate results. A replica exchange molecular dynamics simulation was performed to demonstrate the structural change due to this type of abstraction.

Variation of reaction dynamics for OH hydrogen abstraction from glycine between ab initio levels of theory.

The variation in reaction dynamics of OH hydrogen abstraction from glycine between HF, MP2, CCSD(T), M05-2X, BHandHLYP, and B3LYP levels was demonstrated. The abstraction mode shows distinct patterns between these five levels and determines the barrier height, and the spin density transfer between OH radical and glycine. These differences are mainly resulted from the spin density distribution and geometry of the alpha carbon during the abstraction. The captodative effect which is commonly believed as one of the major factors to stabilize the caron-centered radical can only be observed in DFT levels but not in HF and MP2 levels. Difference in the abstraction energy were found in these calculation levels, by using the result of CCSD(T) as reference, B3LYP, BHandHLYP, and M05-2X underestimated the reaction barrier about 5.1, 0.1, and 2.4 kcal mol(-1), while HF and MP2 overestimated 19.1 kcal mol(-1) and 1.6 kcal mol(-1), respectively. These differences can be characterized by the vibration mode of imaginary frequency of transition states, which indicates the topology around transition states and determines reaction barrier height. In this model system, BHandHLYP provides the best prediction of the energy barrier among those tested methods.

Site specificity of the (alpha)C--H bond dissociation energy for a naturally occurring beta-hairpin peptide-An ab initio study.

A naturally occurring beta-hairpin peptide (PDB ID 1UAO) was used as a model to study the backbone oxidation of a protein with ab initio calculation at the B3LYB/6-31G(d) without any constraints. The (alpha)C--H bond dissociation energy of three different glycyl radicals located at different sites on the beta-hairpin peptide was calculated to evaluate the site specificity of backbone oxidation. The molecular and electronic structures of these glycyl radicals were analyzed to rationalize this site specificity. The overall molecular structure of the alpha-H abstracted beta-hairpin peptide remained almost unchanged with the exception of the local conformation of the attacked residue. However, the (alpha)C--H bond strength varied dramatically among these different sites.