Dirac equation for photons in a fibre: Origin of polarisation.

Spin is a fundamental degree of freedom, which was discovered by Dirac for an electron in his relativistic quantum mechanics, known as the Dirac equation. The origin of spin for a photon is unclear because Maxwell's equations in a vacuum are Lorentz invariant without introducing the concept of spin. Here, the propagation of coherent rays of photons in a graded-index optical fibre is considered to discuss the origin of polarisation for photons using exact solutions of the Laguerre-Gauss and Hermite-Gauss modes. The energy spectrum is massive, and the effective mass is a function of the confinement and orbital angular momentum. The propagation is described by the one-dimensional (1D) non-relativistic Schrödinger equation, which is equivalent to the 2D space-time Klein-Gordon equation by a unitary transformation. The probabilistic interpretation and the conservation law require the factorisation of the Klein-Gordon equation, leading to the 2D Dirac equation with spin. The spin expectation values of photons correspond to the polarisation state on the Poincaré sphere. As an application of the theory, a polarisation interferometer is proposed, whose energy spectrum shows a Dirac cone in the Stokes parameter space.

Synthesis of Interlocked and Non-Interlocked Deca(para-phenylene) Derivatives by Ni-mediated Biaryl Coupling.

Oligo(para-phenylene) (PPn) is a compound composed of directly connected 1,4-phenylene moieties. The synthesis of PPn composed of six or more phenylene moieties with no substituent at the internal phenylene moiety has been challenging because of its low solubility. Herein we synthesized oligo(para-phenylene)[2]rotaxanes, including a deca(para-phenylene)[2]rotaxane, with a defined number of phenylene moieties. Biaryl coupling of iodoarenes mediated by macrocyclic dibenzodihydrophenanthroline-Ni complex was utilized for the first time to synthesize the [2]rotaxanes. Compared to the non-interlocked deca(para-phenylene), the deca(para-phenylene)[2]rotaxane showed higher solubility. The properties of the oligo(para-phenylene)[2]rotaxanes and non-interlocked oligo(para-phenylene)s were analyzed by spectroscopic methods.

A healthy young patient with hepatic portal vein gas due to acute gastric dilatation: a case report.

Hepatic portal vein gas (HPVG) is caused by the influx of gastrointestinal gas into the intrahepatic portal vein as a result of gastrointestinal wall fragility due to ischemia or necrosis. Gastrointestinal tract necrosis is fatal in severe cases. We observed a case of food intake-induced acute gastric dilatation (AGD) in a healthy young male who developed HPVG and underwent conservative treatment. A 25-year-old male presented to our hospital with epigastric pain and nausea the day after excessive food intake. Computed tomography (CT) revealed gas along the intrahepatic portal vein and marked gastric dilatation with large food residue. AGD-induced HPVG was considered. Esophagogastroduodenoscopy (EGD) was not performed at this stage because of the risk of HPVG and AGD exacerbation, and the patient was followed up with intragastric decompression via a nasogastric tube. Food residue and approximately 2 L of liquid without blood were vomited 1 h after the nasogastric tube placement. His symptoms improved after the vomiting episode. An EGD was performed 2 days after undergoing CT. Endoscopic findings revealed extensive erosions and the presence of a whitish coat extending from the fornix to the lower body of the stomach, indicating AGD. HPVG disappeared on the CT scan taken during EGD. Thereafter, symptom relapse and HPVG recurrence were not observed.

Whole-genome analysis of recombinant inbred rice lines reveals a quantitative trait locus on chromosome 3 with genotype-by-environment interaction effects.

Elucidating genotype-by-environment interactions is fundamental for understanding the interplay between genetic and environmental factors that shape complex traits in crops. Genotype-by-environment interactions are of practical importance, as they determine the performance of cultivars grown in different environments, prompting the need for an efficient approach for evaluating genotype-by-environment interactions. Here, we describe a method for genotype-by-environment detection that involves comparing linear mixed models. This method successfully detected genotype-by-environment interactions in rice (Oryza sativa) recombinant inbred lines grown at 3 locations. We identified a quantitative trait locus (QTL) on chromosome 3 that was associated with heading date, grain number, and leaf length. The effect of this QTL on plant growth-related traits varied with environmental conditions, indicating the presence of genotype-by-environment interactions. Therefore, our method enables a powerful genotype-by-environment detection pipeline that should facilitate the production of high-yielding crops in a given environment.

Copper-Catalyzed Borylation of Styrenes by 1,8-Diaminonaphthalene-Protected Diboronic Acid.

We report a concise synthesis of 1,8-diaminonaphthalene-protected diboronic acid (B2(dan)2), which is a promising borylating agent. B2(dan)2 is a bench-stable compound, and it could be utilized for Cu-catalyzed borylation of styrene derivatives. The reaction proceeded in a highly selective manner, and the products were isolated in up to 97% yields. Mechanistic studies revealed that a borate species would be a key intermediate for the borylation reaction.

Indoxyl Sulfate Promotes Metastatic Characteristics of Ovarian Cancer Cells via Aryl Hydrocarbon Receptor-Mediated Downregulation of the Mas Receptor.

Although platinum-combination chemotherapy shows a high response rate at the primary site, epithelial ovarian cancer (EOC) treatment remains challenging because of tumor recurrence and metastasis. Recent studies have revealed that chemotherapy paradoxically promotes cancer cell survival, proliferation, and metastasis, although the reason for this remains unclear. The underlying molecular mechanisms that contribute to chemotherapy-induced metastasis need to be elucidated to establish effective therapeutic strategies. Acute kidney injury is a known side effect of cisplatin treatment, and kidney dysfunction results in the accumulation of uremic toxins in the serum. The present study aimed to investigate whether indoxyl sulfate (IS), a representative uremic toxin, affects the pathophysiology of EOC. In this study, IS reduced the expression of Mas receptor (MasR) in cultured human EOC cells. Both knockdown of the aryl hydrocarbon receptor (AhR), which is an intracellular IS receptor, and inhibition of AhR function suppressed IS-mediated downregulation of MasR in SK-OV-3 cells. IS induced the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in an AhR-dependent manner. Inhibition of the STAT3 pathway or reactive oxygen species production suppressed the IS-mediated reduction of MasR. IS stimulated cell migration and invasion of SK-OV-3 cells in an AhR-dependent manner. Cisplatin-nephropathy model mice exhibited elevated levels of serum IS accompanied by elevated levels of blood urea nitrogen and serum creatinine. Furthermore, intraperitoneal administration of IS in mice promoted tumor growth and metastasis. Finally, we found that the MasR agonist Ang-(1-7) suppressed the IS-mediated effects on cell proliferation, migration, and invasion of SK-OV-3 cells. However, the knockdown of MasR expression by specific small interfering RNA in the absence of IS resulted in only minimal promotion of cell migration and invasion. These findings demonstrate that IS promotes malignancy in ovarian cancer via AhR-mediated downregulation of MasR function, whereas Ang-(1-7) attenuates this effect, thereby suggesting that Ang-(1-7) could provide a future treatment strategy for this cancer type.

Synthesis and stereochemistry of chiral aza-boraspirobifluorenes with tetrahedral boron-stereogenic centers.

We have synthesized chiral aza-boraspirobifluorenes and evaluated their structural and photophysical properties. Enantiomers were separated by chiral HPLC on a semi-preparative scale, and the absolute stereochemistry was determined by comparison of experimental circular dichroism (CD) spectra and theoretical electronic CD (ECD) spectra. A kinetic analysis combined with theoretical calculations revealed that the rate-determining step of the racemization involves the cleavage of the B-N bond.

Dynamic Au-C σ-Bonds Leading to an Efficient Synthesis of [n]Cycloparaphenylenes (n = 9-15) by Self-Assembly.

The transmetalation of the digold(I) complex [Au2Cl2(dcpm)] (1) (dcpm = bis(dicyclohexylphosphino)methane) with oligophenylene diboronic acids gave the triangular macrocyclic complexes [Au2(C6H4) x (dcpm)]3 (x = 3, 4, 5) with yields of over 70%. On the other hand, when the other digold(I) complex [Au2Cl2(dppm)] (1') (dppm = bis(diphenylphosphino)methane) was used, only a negligible amount of the triangular complex was obtained. The control experiments revealed that the dcpm ligand accelerated an intermolecular Au(I)-C σ-bond-exchange reaction and that this high reversibility is the origin of the selective formation of the triangular complexes. Structural analyses and theoretical calculations indicate that the dcpm ligand increases the electrophilicity of the Au atom in the complex, thus facilitating the exchange reaction, although the cyclohexyl group is an electron-donating group. Furthermore, the oxidative chlorination of the macrocyclic gold complexes afforded a series of [n]cycloparaphenylenes (n = 9, 12, 15) in 78-88% isolated yields. The reorganization of two different macrocyclic Au complexes gave a mixture of macrocyclic complexes incorporating different oligophenylene linkers, from which a mixture of [n]cycloparaphenylenes with various numbers of phenylene units was obtained in good yields.

Chiral germanium micro-gears for tuning orbital angular momentum.

Group IV light sources with vertical emission and non-zero orbital-angular momentum (OAM) promise to unlock many novel applications. In this report, we demonstrate cylindrically symmetrical germanium micro-gear cavities, fabricated by etching a grating around the circumference of standard micro-disks, with periods ranging from 14 to 22. Photoluminescence (PL) measurements were done to identify the confined whispering-gallery modes (WGM). Finite-difference time-domain (FDTD) simulations were conducted to map the resonant modes to their modal profiles and characteristics. Vertical emission of WGMs with non-zero OAM was demonstrated, with a clear dependence of the OAM order ([Formula: see text]) on the WGM azimuthal order and the number of micro-gear grating periods. As the chirality, or the direction of rotation, is not controlled in a symmetrical cavity, we propose introducing staircase or triangular-shaped gear periods resulting in an asymmetry. By choosing the diameter, number of periods, and the asymmetrical direction of the gear-teeth, it is possible to generate OAM signals with certain wavelength, OAM order and chirality.

Phenanthroline based rotaxanes: recent developments in syntheses and applications.

The advancements in the field of mechanically interlocked molecular systems (MIMs) has concurrently restructured the material chemistry frontiers and provided ample scope to explore new dimensions for applications and diversity creation. Among all these molecular entities, rotaxanes have a special locale and many research groups over the globe have contributed to their current niche in supramolecular chemistry. From refinements for better yielding synthetic strategies to their application oriented designs, this field has come a long way and is well inclined for further developments. In this review, we aim to document the contemporary developments in the synthesis of phenanthroline (phen) based rotaxanes. In addition to providing a comprehensive account of various subtypes of these rotaxanes and their stitching strategies, their applications, wherever discernible, will be duely highlighted.

Conformational Control of [2]Rotaxane by Hydrogen Bond.

A series of [2]rotaxanes with various functional groups in the axle component was synthesized by the oxidative dimerization of alkynes, which is mediated by a macrocyclic phenanthroline-Cu complex. The rotaxanes were fully characterized by spectroscopic methods, and the structure of a rotaxane was determined by X-ray crystallographic analysis. The interaction between the ring component and the axle component was studied in detail to understand the conformation of the rotaxanes. The presence of the hydrogen bond between the phenanthroline moiety in the macrocyclic component and the acidic proton in the axle component influenced the conformation of rotaxane.

Ge Ion Implanted Photonic Devices and Annealing for Emerging Applications.

Germanium (Ge) ion implantation into silicon waveguides will induce lattice defects in the silicon, which can eventually change the crystal silicon into amorphous silicon and increase the refractive index from 3.48 to 3.96. A subsequent annealing process, either by using an external laser or integrated thermal heaters can partially or completely remove those lattice defects and gradually change the amorphous silicon back into the crystalline form and, therefore, reduce the material's refractive index. Utilising this change in optical properties, we successfully demonstrated various erasable photonic devices. Those devices can be used to implement a flexible and commercially viable wafer-scale testing method for a silicon photonics fabrication line, which is a key technology to reduce the cost and increase the yield in production. In addition, Ge ion implantation and annealing are also demonstrated to enable post-fabrication trimming of ring resonators and Mach-Zehnder interferometers and to implement nonvolatile programmable photonic circuits.

The Aza-Prins Reaction of 1,2-Dicarbonyl Compounds with 3-Vinyltetrahydroquinolines: Application to the Synthesis of Polycyclic Spirooxindole Derivatives.

The aza-Prins reaction of 6,7-dimethoxy-3-vinyl-1,2,3,4-tetrahydroquinoline (1) with 1,2-dicarbonyl compounds proceeded smoothly in the presence of HCl, and the corresponding tricyclic benzazocines were isolated in yields of 20-86%. The reaction proceeded in a stereoselective manner, and the formation of the 2,4-trans isomer was observed. The reaction of 1 with an enantiopure ketoester gave the corresponding tricyclic benzazocine as a mixture of diastereomers. The diastereomers were easily separated and converted to enantiopure tricyclic benzazocines. The synthesis of spirooxindole derivatives was achieved by the reaction of 1 with isatin derivatives.

Analytical approach for lubricant characterization of excipients using the surface replication method.

Lubricants are indispensable pharmaceutical ingredients for preventing tableting failure due to powder adhesion to the die wall. The impact of lubricants was evaluated with use of the Binding Identification for Net Detriment (BIND) surface replication method. Raloxifene hydrochloride (RH) was selected as a model chemical with high adhesion, and four commercially available tablet lubricants - stearic acid, sodium stearyl fumarate, calcium stearate, and magnesium stearate - were used for RH formulation. BIND was applied to the die wall to analyze the effect of various lubricants on binding properties. The preparations without lubricants showed poor tableting properties as evidenced by as much as 61.7% powder adhesion density. Lubricants significantly altered the binding properties, yielding powder adhesion densities of 40.2% (stearic acid), 29.7% (stearyl sodium fumarate), 23.0% (calcium stearate), and 13.6% (magnesium stearate). Evaluation of three grades of magnesium stearate resulted in a two-fold difference between the highest and the lowest powder adhesion density. Throughout the work, conventional methods including visual observations and measurement of ejection force were unable to provide qualitative/quantitative evaluations. The ejection process depends on both axial force and radial force; however, the ejection force show only the axial force. At the same time, visual observation could release significant qualitative results. However, BIND allowed qualitative and quantitative analysis of the binding properties. BIND is a promising assessment method for analyzing the impacts of various lubricants on binding properties and for optimizing RH formulations.

(Z)-Selective Hydrosilylation and Hydroboration of Terminal Alkynes Enabled by Ruthenium Complexes with an N-Heterocyclic Carbene Ligand.

Metal-catalyzed trans-1,2-hydrosilylations and hydroborations of terminal alkynes that generate synthetically valuable (Z)-alkenylsilanes and (Z)-alkenylboranes remain challenging due to the (E)-selective nature of the reactions and the formation of the thermodynamically unfavorable (Z)-isomer. The development of new, efficient catalytic systems for the (Z)-selective hydrosilylation and hydroboration of terminal alkynes is thus highly desirable from a fundamental perspective as it would deepen our understanding of the metal-catalyzed (Z)-selective hydrosilylation and hydroboration of terminal alkynes. This personal account describes our research for developing a ruthenium complex that can efficiently catalyze the hydrosilylation and hydroboration of terminal alkynes, and for exploring the factors controlling (Z)-selectivity of the reactions. Our effort into the activation of B-protected boronic acids, R-B(dan) (dan=naphthalene-1,8-diaminato), that was believed not to participate in Suzuki-Miyaura cross-coupling, is also discussed.

Direct observation of surface charge redistribution in active nanoscale conducting channels by Kelvin Probe Force Microscopy.

Surface-exposed uniformly doped silicon-on-insulator channels are fabricated to evaluate the accuracy of Kelvin Probe Force Microscopy (KPFM) measured surface potential and reveals the role of surface charge on the exposed channel operated in the ambient environment. First, the quality of the potential profile probed in the vacuum environment is assessed by the consistency of converted resistivity from KPFM result to the resistivity extracted by the other three methods. Second, in contrast to the simulated and vacuum surface potential profile and image, the ambient surface potential is bent excessively at the terminals of the channel. The excessive bending can be explained by the movement of surface charge under the drive of geometry induced strong local electric field from the channel and results in non-uniform distribution. The dynamic movement of surface charges is proved by the observation of time-dependent potential drift in the ambient measurement. The result suggests the surface charge effect should be taken into account of the measurement of the surface potential in the ambient environment and the design of charge sensitive devices whose surfaces are exposed to air or in ambient conditions in their operation.

Probing hole spin transport of disorder quantum dots via Pauli spin-blockade in standard silicon transistors.

Single hole transport and spin detection is achievable in standard p-type silicon transistors owing to the strong orbital quantization of disorder based quantum dots. Through the use of the well acting as a pseudo-gate, we discover the formation of a double-quantum dot system exhibiting Pauli spin-blockade and investigate the magnetic field dependence of the leakage current. This enables attributes that are key to hole spin state control to be determined, where we calculate a tunnel couplingtcof 57µeV and a short spin-orbit lengthlSOof 250 nm. The demonstrated strong spin-orbit interaction at the interface when using disorder based quantum dots supports electric-field mediated control. These results provide further motivation that a readily scalable platform such as industry standard silicon technology can be used to investigate interactions which are useful for quantum information processing.

Silicon erasable waveguides and directional couplers by germanium ion implantation for configurable photonic circuits.

A novel technique for realization of configurable/one-time programmable (OTP) silicon photonic circuits is presented. Once the proposed photonic circuit is programmed, its signal routing is retained without the need for additional power consumption. This technology can potentially enable a multi-purpose design of photonic chips for a range of different applications and performance requirements, as it can be programmed for each specific application after chip fabrication. Therefore, the production costs per chip can be reduced because of the increase in production volume, and rapid prototyping of new photonic circuits is enabled. Essential building blocks for the configurable circuits in the form of erasable directional couplers (DCs) were designed and fabricated, using ion implanted waveguides. We demonstrate permanent switching of optical signals between the drop port and through the port of the DCs using a localized post-fabrication laser annealing process. Proof-of-principle demonstrators in the form of generic 1×4 and 2×2 programmable switching circuits were fabricated and subsequently programmed.

Transient appearance of Ca2+ -permeable AMPA receptors is crucial for the production of repetitive LTP-induced synaptic enhancement (RISE) in cultured hippocampal slices.

We have previously shown that repetitive induction of long-term potentiation (LTP) by glutamate (100 µM, 3 min, three times at 24-hr intervals) provoked long-lasting synaptic enhancement accompanied by synaptogenesis in rat hippocampal slice cultures, a phenomenon termed RISE (repetitive LTP-induced synaptic enhancement). Here, we examined the role of Ca2+ -permeable (CP) AMPA receptors (AMPARs) in the establishment of RISE. We first found a component sensitive to the Joro-spider toxin (JSTX), a blocker of CP-AMPARs, in a field EPSP recorded from CA3-CA1 synapses at 2-3 days after stimulation, but this component was not found for 9-10 days. We also observed that rectification of AMPAR-mediated current appeared only 2-3 days after stimulation, using a whole-cell patch clamp recording from CA1 pyramidal neurons. These findings indicate that CP-AMPAR is transiently expressed in the developing phase of RISE. The blockade of CP-AMPARs by JSTX for 24 hr at this developing phase inhibited RISE establishment, accompanied by the loss of small synapses at the ultrastructural level. These results suggest that transiently induced CP-AMPARs play a critical role in synaptogenesis in the developing phase of long-lasting hippocampal synaptic plasticity, RISE.

Folate-appended cyclodextrin carrier targets ovarian cancer cells expressing the proton-coupled folate transporter.

Folate receptor alpha (FRα) is overexpressed in >80% of epithelial ovarian cancer (EOC). Accordingly, folate is attracting attention as a targeting ligand for EOC. For EOC patients, paclitaxel (PTX) is generally used as a first-line chemotherapeutic agent in combination with platinum-based drugs. Cyclodextrin (CyD) is a potential new formulation vehicle for PTX that could replace Cremophor-EL, a traditional formulation vehicle that causes significant side effects, including neutropenia. Several years ago, folate-appended ß-CyD (Fol-c1 -ß-CyD) was developed as an FRα-targeting drug carrier, but its efficacy as a treatment for EOC remains to be determined. In this study, we assessed the antitumor activity of PTX in Fol-c1 -ß-CyD (PTX/Fol-c1 -ß-CyD) in EOC-derived cell lines. We found that PTX/Fol-c1 -ß-CyD killed not only FRα-expressing cells but also FRα-negative cells. In the FRα-negative A2780 cells, knockdown of proton-coupled folate transporter (PCFT) significantly decreased the cytotoxicity of PTX/Fol-c1 -ß-CyD, whereas knockdown of FRα did not. By contrast, knockdown of either FRα or proton-coupled folate transporter (PCFT) decreased the cytotoxicity of PTX/Fol-c1 -ß-CyD in FRα-expressing SK-OV-3 cells. Furthermore, the cytotoxicity of PTX/Fol-c1 -ß-CyD in A2780 cells was increased at acidic pH, and this increase was suppressed by PCFT inhibitor. In mice intraperitoneally inoculated with FRα-expressing or PCFT-expressing EOC cells, intraperitoneal administration of PTX/Fol-c1 -ß-CyD significantly suppressed the growth of both types of EOC cells relative to PTX alone, without inducing a significant change in the neutrophil/white blood cell ratio. Our data suggest that Fol-c1 -ß-CyD targets not only FRα but also PCFT, and can efficiently deliver anticancer drugs to EOC cells in the peritoneal cavity.