Machine Learning Seams of Conical Intersection: A Characteristic Polynomial Approach.

The machine learning of potential energy surfaces (PESs) has undergone rapid progress in recent years. The vast majority of this work, however, has been focused on the learning of ground state PESs. To reliably extend machine learning protocols to excited state PESs, the occurrence of seams of conical intersections between adiabatic electronic states must be correctly accounted for. This introduces a serious problem, for at such points, the adiabatic potentials are not differentiable to any order, complicating the application of standard machine learning methods. We show that this issue may be overcome by instead learning the coordinate-dependent coefficients of the characteristic polynomial of a simple decomposition of the potential matrix. We demonstrate that, through this approach, quantitatively accurate machine learning models of seams of conical intersection may be constructed.

Isotretinoin Exposure and Risk of Inflammatory Bowel Disease: A Systematic Review with Meta-Analysis and Trial Sequential Analysis.

BACKGROUND: Cases of inflammatory bowel disease (IBD) following isotretinoin use have been reported previously, but whether isotretinoin exposure is associated with IBD has been unclear. OBJECTIVE: The aim was to evaluate whether isotretinoin use is associated with IBD. METHODS: We performed a systematic review and searched MEDLINE, Embase, and CENTRAL databases from inception to January 27, 2023 for relevant case-control and cohort studies. Our outcome was the pooled odds ratio (OR) for IBD and its two subtypes (Crohn disease and ulcerative colitis) in relation to isotretinoin exposure. We conducted a random-effects model meta-analysis and a sensitivity analysis by excluding low-quality studies. A subgroup analysis was undertaken by including studies considering antibiotic use. A trial sequential analysis (TSA) was performed to test the robustness of the conclusiveness of our results. RESULTS: We included eight studies (four case-control and four cohort studies) with a total of 2,522,422 participants. The meta-analysis found no increased odds for IBD among patients receiving isotretinoin (OR 1.01; 95% confidence interval [CI] 0.80-1.27). Nor did the meta-analysis find increased odds for either Crohn disease (OR 0.87; 95% CI 0.65-1.15) or ulcerative colitis (OR 1.27; 95% CI 0.94-1.73) associated with isotretinoin exposure. The sensitivity and subgroup analyses produced similar results. In TSA, the Z-curve reached the futility boundaries when using relative risk reduction thresholds ranging from 5% to 15%. CONCLUSION: This meta-analysis with TSA found no evidence of an association of isotretinoin use with IBD. Isotretinoin should not be withheld because of unnecessary concerns for the development of IBD. PROSPERO REGISTRATION NO: CRD42022298886.

Risk for incident suicidality among psoriasis patients: a systematic review and meta-analysis.

Previous meta-analyses have produced conflicting conclusions about suicidality risk among psoriasis patients. We aimed to update the evidence on the risk for the whole continuum of incident suicidality in psoriasis patients. We performed an update systematic review and meta-analysis and searched CENTRAL, PubMed, and Embase from January 1, 2017 to August 14, 2021 for relevant new cohort studies and incorporated new studies into our previous systematic review. Random-effects model meta-analysis was used to obtain pooled hazard ratio (HR) with 95% confidence interval (CI). Subgroup analysis was conducted according to age and disease severity. A total of 12 studies were included in this meta-analysis. We detected no significant differences in the risk for incident completed suicide (HR 1.33, 95% CI 0.91-1.95), suicide attempt (HR 1.22, 95% CI 0.96-1.56), suicidal behavior (HR 1.08, 95% CI 0.98-1.19), and suicide ideation (HR 1.74, 95% CI 0.99-3.06) between psoriasis patients and non-psoriatic controls. In the subgroup analysis based on age, an increased risk for incident suicide ideation was observed in pediatric subgroup (HR 1.50, 95% CI 1.12-2.03). The updated evidence suggests no increased risk for whole continuum of incident suicidality spectrum in psoriasis patients but an increased risk for incident suicide ideation among pediatric psoriasis patients. Involving mental health professionals may be crucial in psoriasis management especially in young patients.

Biologic Disease-Modifying Antirheumatic Drugs for Preventing Radiographic Progression in Psoriatic Arthritis: A Systematic Review and Network Meta-Analysis.

The prevention of joint deformity is among the most important treatment goals of psoriatic arthritis. Some biologics disease-modifying antirheumatic drugs (bDMARDs) have been demonstrated to be effective for both the skin and joints, as well as for slowing radiographic progression. However, there has been a lack of direct comparisons of bDMARDs. To evaluate the comparative effects of bDMARDs in preventing radiographic progression in psoriatic arthritis, we conducted a systematic review and network meta-analysis. On March 7 2022, a search for relevant randomized trials was conducted on MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. Our outcomes included radiographic non-progression, a mean change in the total radiographic score, and adverse events leading to discontinuation (DAE) at week 24. We included 11 trials on 10 bDMARDs, involving 4010 participants. Most bDMARDs were more effective than placebos in achieving radiographic non-progression, including adalimumab (odds ratio (OR) 4.7, 95% confidence interval (CI) 2.66-8.29), etanercept (OR 4.19, 95% CI 1.65-10.61), certolizumab pegol (OR 2.83, 95% CI 1.55-5.2), secukinumab 300 mg (OR 2.63, CI 1.62-4.27), infliximab (OR 2.54, CI 1.13-5.69), ixekizumab (OR 2.22, 95% CI 1.06-4.65), golimumab (OR 2.21, 95% CI 1.24-3.93), and abatacept (OR 1.54, 95% CI 1.03-2.28). A significant reduction in the total radiographic score was found in infliximab (standardized mean difference (SMD) -0.59, 95% CI -0.87, -0.3), etanercept (SMD -0.51, 95% CI -0.78, -0.23), adalimumab (SMD -0.45, 95% CI -0.64, -0.26), ixekizumab (SMD -0.37, 95% CI -0.62, -0.12), secukinumab 300 mg (SMD -0.33, 95% CI -0.50, -0.15), golimumab (SMD -0.33, 95% CI -0.58, -0.09), secukinumab 150 mg (SMD -0.25, 95% CI -0.43, -0.07), certolizumab pegol (SMD -0.23, 95% CI -0.44, -0.03), and ustekinumab (SMD -0.19, 95% CI -0.35, -0.33). No significant differences in DAE were detected between bDMARDs. In conclusion, anti-tumor necrosis factor agents (adalimumab, infliximab, and etanercept) may be preferred for treating psoriatic arthritis for their superiority in preventing radiographic progression.

85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering.

In this study, high internal-quantum-efficiency (IQE) AlGaN multiple quantum wells (MQWs) were successfully demonstrated on low-defect-density AlN templates with nano-patterned sapphire substrates. These templates consisted of AlN structures with 0∼30 periods superlattices (SLs) by alternating high (100) and low (25) V/III ratios under a low growth temperature (1130 °C). Compared to conventional high crystal-quality AlN epilayers achieved at temperatures ≥1300 °C, lower thermal budget can reduce the production cost and wafer warpage. Via optimization of the SL period, the AlN crystallinity was systematically improved. Strong dependence of SL period number on the X-ray full-width-at-half-maximum (FWHM) of the AlN epilayer was observed. The AlN template with 20-period SLs exhibited the lowest FWHM values for (0002) and (10i2), namely 331 and 652 arcsec, respectively, as well as an ultra-low etching pit density of 1 × 105 cm-2. The relative IQE of 280 nm AlGaN MQWs exhibited a dramatically increase from 22.8% to 85% when the inserted SL increased from 0 to 20 periods. It has hardly ever been reported for the AlGaN MQW sample. The results indicate that the engineered AlN templates have high potential applications in deep ultraviolet light emitters.

Effect of non-vacuum thermal annealing on high indium content InGaN films deposited by pulsed laser deposition.

InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications.

High thermal stability of high indium content InGaN films grown by pulsed laser deposition.

Thermal stability on the structural and optical properties of high indium content InGaN films grown using pulsed laser deposition (PLD) was investigated through long-duration and high-temperature annealing. X-ray diffraction and cathode- luminescence measurements of the 33% indium InGaN revealed no differences in the line-shape and peak position even after annealing at 800°C for 95 min; similar structural stability was found for the 60% samples after annealing for 75 min. The higher thermal stability is attributed to nanoscale InN domains with different orientations create mixed-polarity InGaN/InN interfaces, resulting in higher activation energies at interfaces and increasing the thermal stability of the material. Furthermore, the InGaN films were subjected to metalorganic chemical vapor deposition treatment to regrow a GaN layer; results are promising for the development of high thermal stability InGaN films using the PLD technique.

High indium content InGaN films grown by pulsed laser deposition using a dual-compositing target.

High indium compositions InGaN films were grown on sapphires using low temperature pulse laser deposition (PLD) with a dual-compositing target. This target was used to overcome the obstacle in the InGaN growth by PLD due to the difficulty of target preparation, and provided a co-deposition reaction, where InGaN grains generated from the indium and GaN vapors deposit on sapphire surface and then act as nucleation seeds to promote further InGaN growth. The effects of co-deposition on growth mechanisms, surface morphology, and electrical properties of films were thoroughly investigated and the results clearly show promise for the development of high indium InGaN films using PLD technique with dual-compositing targets.

Donnan potential of dilute colloidal dispersions: Monte Carlo simulations.

Donnan equilibrium between a salt-free colloidal dispersion and an electrolyte solution has been investigated by Monte Carlo simulations. The Donnan potential is directly calculated by considering two compartments separated by a semipermeable membrane. In order to understand the role played by colloid-ion interactions, the influences of colloidal characteristics, including particle size R, intrinsic particle charge Z, counterion valency z(c), and concentration c(p), on Donnan potential Psi(D) and effective charge Z(eff) are examined. Our simulations show that the electroneutrality condition is not followed in both compartments and the Donnan potential arises due to the net charge density. The Donnan potential grows by increasing c(p) and Z(eff) and by decreasing dielectric constant epsilon(r), i.e., Psi(D) approximately Z(eff)c(p)/epsilon(r) approximately. Note that the effective charge varies with R,Z,c(p),epsilon(r) and z(c) as well. When the salt concentration is increased, the net charge density is lowered and thus the Donnan potential decays accordingly. The validity of the classical theory based on the Nernst equation and the electroneutrality assumption is also examined. In general, the simulation results at high-salt condition can be well represented by such mean-field theory.

Osmotic pressure and virial coefficients of star and comb polymer solutions: dissipative particle dynamics.

The effects of macromolecular architecture on the osmotic pressure pi and virial coefficients (B(2) and B(3)) of star and comb polymers in good solvents are studied by dissipative particle dynamics simulations for both dilute and semiconcentrated regimes. The dependence of the osmotic pressure on polymer concentration is directly calculated by considering two reservoirs separated by a semipermeable, fictitious membrane. Our simulation results show that the ratios A(n+1) identical with B(n+1)/R(g)(3n) are essentially constant and A(2) and A(3) are arm number (f) dependent, where R(g) is zero-density radius of gyration. The value of dimensionless virial ratio g = A(3)/A(2)(2) increases with arm number of stars whereas it is essentially arm number independent for comb polymers. In semiconcentrated regime the scaling relation between osmotic pressure and volume fraction, pi proportional to phi(lambda), still holds for both star and comb polymers. For comb polymers, the exponent lambda is close to lambda(*) (approximately = 2.73 for linear chains) and is independent of the arm number. However, for star polymers, the exponent lambda deviates from lambda(*) and actually grows with increasing the arm number. This may be attributed to the significant ternary interactions near the star core in the many-arm systems.

Equilibrium sedimentation profile of dilute, salt-free charged colloids.

The sedimentation profile of a dilute colloidal solution follows the barometric distribution owing to the balance between gravitational force and thermal fluctuation. However, the electrostatic interactions may lead to significant deviation even in the low volume fraction limit (e.g., 10(-5)). On the basis of Monte Carlo simulations for a dilute, salt-free colloidal dispersion, five regimes can be identified through the resulting colloidal sedimentation profile and the counterion distribution. The electrostatic interactions depends on the Coulomb strength E(c) defined as the ratio of the Bjerrum length to the colloid size. At weak colloid-ion attractions (small E(c)), counterions tend to distribute uniformly in the container. However, both barometric and inflated profiles of colloids can be observed. On the contrary, at strong colloid-ion attraction (large E(c)), counterions accumulate in the vicinity of the colloids. Significant counterion condensation effectively decreases the strength of colloid-colloid repulsion and barometric profile of colloids can be obtained as well. As a result, the sedimentation profile and counterion distribution are indicative of the strength of effective colloid-colloid and colloid-ion interactions. It is also found that local electroneutrality condition is generally not satisfied and charge separation (or internal electric field) is neither a sufficient nor necessary condition for nonbarometric distributions.

A-B diblock copolymer micelles: effects of soluble-block length and component compatibility.

Micellization of a diblock copolymer in dilute solution is studied by dissipative particle dynamics. The influence of the compatibility between blocks A and B and the interaction between the insoluble block and solvent on aggregation number P and micellar core radius Rc are examined. The micelle size distribution is obtained, and it is quite polydisperse. Different from the scaling theory for starlike micelles, the mean aggregation number based on weight average

w decreases with increasing soluble-block length NA and the power law relation can be obtained,

w approximately NA(-alpha). Similarly, the micellar core radius declines with NA, following Rc approximately NA(-beta) with beta=alpha/3. However, the exponent depends on the mutual compatibility between soluble and insoluble blocks. For the same composition, the incompatible diblocks form a smaller micelle and its aggregation number declines with a smaller exponent alpha. When NA approximately NB, the micelles deviate significantly from the spherical shape and solvophilic blocks are observed to be entrapped in the solvophobic core for compatible diblocks.

Effects of multivalent salt addition on effective charge of dilute colloidal solutions.

The effective charge Z* is often invoked to account for the accumulation of counterions near the colloid with intrinsic charge Z. Although the ion concentrations c(i) are not uniform in the solution due to the presence of the charged particle, their chemical potentials are uniform everywhere. Thus, on the basis of ion chemical potential, effective ion concentrations c(i)*, which can be experimentally measured by potentiometry, are defined with the pure salt solution as the reference state. The effective charge associated with the charged particle can then be determined by the global electroneutrality condition. Monte Carlo simulations are performed in a spherical Wigner-Seitz cell to obtain the effective charge of the colloid. In terms of the charge ratio alpha=Z*/Z, the effects of added salt concentration, counterion valency, and particle charge are examined. The effective charge declines with increasing salt concentration and the multivalent salt is much more efficient in reducing the effective charge of the colloidal solution. Moreover, the extent of effective charge reduction is decreased with increasing intrinsic charge for a given concentration of added salt. Those results are qualitatively consistent with experimental observations by electrophoresis.

Characterization of natural chitosan membranes from the carapace of the soldier crab Mictyris brevidactylus and its application to immobilize glucose oxidase in amperometric flow-injection biosensing system.

This study investigated characteristics of a chitosan membrane from the carapace of the soldier crab Mictyris brevidactylus intended to construct an amperometric biosensor. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used in this study to characterize these chitosan membranes intended for constructing enzymatic biosensors. Chitosan membranes suffering various durations (>10 min) of deacetylation had small charge-transfer resistances (<7.88 kohms) but large double-layer capacitances (>0.55 microF). They were found in EIS where both the solution resistance and Warburg impedance upon electrode interface were almost independent of the durations and degree of deacetylation. The degree of deacetylation and the thickness of chitosan membranes were also determined. Membrane thickness was slightly dependent with the duration but degree of deacetylation was slightly dependent on the duration. Chitosan membranes with various thicknesses suffered various durations of deacetylation, but this did not influence their electrochemical characteristics. The chitinous membrane was covalently immobilized with glucose oxidase (EC 1.3.4.3) and then attached onto the platinum electrode of a homemade amperometric flow cell. Sensor signal was linearly related to glucose concentration (r=0.999 for glucose up to 1.0 mM). The system was sensitive (S/N>5 for 10 microM glucose) and reproducible (CV<1.3% for 50 microM glucose, n=5).

Counterion condensation and release in micellar solutions.

Counterion condensation and release in micellar solutions are investigated by direct measurement of counterion concentration with ion-selective electrode. Monte Carlo simulations based on the cell model are also performed to analyze the experimental results. The degree of counterion condensation is indicated by the concentration ratio of counterions in the bulk to the total ionic surfactant added, alpha< or =1. The ionic surfactant is completely dissociated below the critical micelle concentration (cmc). However, as cmc is exceeded, the free counterion ratio alpha declines with increasing the surfactant concentration and approaches an asymptotic value owing to counterion condensation to the surface of the highly charged micelles. Micelle formation leads to much stronger electrostatic attraction between the counterion and the highly charged sphere in comparison to the attraction of single surfactant ion with its counterion. A simple model is developed to obtain the true degree of ionization, which agrees with our Monte Carlo results. Upon addition of neutral polymer or monovalent salts, some of the surfactant counterions are released to the bulk. The former is due to the decrease of the intrinsic charge (smaller aggregation number) and the degree of ionization is increased. The latter is attributed to competitive counterion condensation, which follows the Hefmeister series. This consequence indicates that the specific ion effect plays an important role next to the electrostatic attraction.

Effective charges of polyelectrolytes in a salt-free solution based on counterion chemical potential.

The phenomenon of counterion condensation around a flexible polyelectrolyte chain with N monomers is investigated by Monte Carlo simulations in terms of the degree of ionization alpha, which is proportional to the effective charge. It is operationally defined as the ratio of observed to intrinsic counterion concentration, alpha = co/ci. The observed counterion concentration in the dilute polyelectrolyte solution is equivalent to an electrolyte solution of concentration co with the same counterion chemical potential. It can be determined directly by thermodynamic experiments such as ion-selective electrode. With the polyelectrolyte fixed at the center of the spherical Wigner-Seitz cell, the polymer conformation, counterion distribution, and chemical potential can be obtained. Our simulation shows that the degree of ionization rises as the polymer concentration decreases. This behavior is opposite to that calculated from the infinitely long charged rod model, which is often used to study counterion condensation. Moreover, we find that, for a specified line charge density, alpha decreases with an increment in chain length and chain flexibility. In fact, the degree of ionization is found to decline with increasing polymer fractal dimension, which can be tuned by varying bending modulus and solvent quality. Those results can be qualitatively explained by a simple model of two-phase approximation.

Charge renormalization of charged spheres based on thermodynamic properties.

At strong electrostatic coupling, counterions are accumulated in the vicinity of the surface of the charged particle with intrinsic charge Z. In order to explain the behavior of highly charged particles, effective charge Z(*) is therefore invoked in the models based on Debye-Huckel approximation, such as the Derjaguin-Landau-Verwey-Overbeek potential. For a salt-free colloidal suspension, we perform Monte Carlo simulations to obtain various thermodynamic properties omega in a spherical Wigner-Seitz cell. The effect of dielectric discontinuity is examined. We show that at the same particle volume fraction, counterions around a highly charged sphere with Z may display the same value of omega as those around a weakly charged sphere with Z(*), i.e., omega(Z)=omega(Z(*)). There exists a maximally attainable value of omega at which Z=Z(*). Defining Z(*) as the effective charge, we find that the effective charge passes through a maximum and declines again due to ion-ion correlation as the number of counterions is increased. The effective charge is even smaller if one adopts the Debye-Huckel expression omega(DH). Our results suggest that charge renormalization can be performed by chemical potential, which may be observed in osmotic pressure measurements.

Use of chitosan membrane from the carapace of the soldier crab Mictyris brevidactylus for biosensor construction.

Glucose oxidase (EC 1.3.4.3) was immobilized on chitosan membrane (<0.1 mm in thickness) prepared from the carapace of the soldier crab Mictyris brevidactylus. A glucose electrode was constructed by covering a platinum electrode (2.0 mm in diameter) with the enzyme membrane. The enzyme electrode sensed glucose amperometrically (1.0 micro A/mM, with linear range up to 0.5 mM, r = 0.999) when positively imposed with 0.6 V against an Ag/AgCl reference electrode. The glucose biosensor was sensitive (<0.1 micro M, S/N > 3), reproducible (CV for 55 micro M glucose <3%, n = 5), reagentless, and durable for months.