Interfacial local field and surface response coefficients.

The interfacial local field is of critical importance in data analysis to deduce intrinsic surface responses from optical measurements of interfaces of condensed media but has not yet been well interrogated. We present here a simple approach to find local fields approximately at various interfaces of isotropic or nearly isotropic media. We divide a medium into atomic planes or molecular layers. It is found that the dipolar field contribution to the local field in a plane or layer from induced dipoles residing in planes beyond the nearest neighbor planes or layers is negligible; in many cases, the contribution is dominated by in-plane dipoles and the local field has a simple expression very much like that for an isotropic bulk. This finding allows us to calculate approximate local field variation at various interfaces. With the interfacial local field known, intrinsic surface response coefficients can be extracted from the optically measured surface responses.

[Finite element analyses of retention of removable partial denture circumferential clasps manufactured by selective laser melting].

OBJECTIVE: To compare the retentions of different designs of cobalt-chromium (Co-Cr), pure titanium (CP Ti), and titanium alloy (Ti-6Al-4V) removable partial denture (RPD) circumferential clasps manufactured by selective laser melting (SLM) and to analyze the stress distribution of these clasps during the removal from abutment teeth. METHODS: Clasps with clasp arm size A (1.9 mm width/1.1 mm thickness at the body and 0.8-taper) or B (1.2 times A) and 0.25 mm or 0.50 mm undercut engagement were modeled on a prepared first premolar die, named as designs A1, A2, A3, and A4, respectively. The density and elastic modulus of SLM-built Co-Cr, CP Ti, and Ti-6Al-4V were measured and given to different groups of clasps. The density, elastic modulus, and Poisson ' s ratio of enamel were given to the die. The control group was the cast Co-Cr clasp with design A1, to which the density and elastic modulus of cast Co-Cr alloy were given. The Poisson's ratio of all metals was 0.33. The initial 5 N dislodging force was applied, and the maximum displacement of the clasp along the insertion path was computed. The load was reapplied with an increment of 5 N than in the last simulation until the clasp was completely dislodged. The retentive force range of different groups of clasps was obtained. The retentive forces of the SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with equivalent computed retentive force range to the control group were validated through the insertion/removal experiment. The von Mises stress distributions of these three groups of SLM-built clasps under 15 N loads were analyzed. RESULTS: SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with designs B1 or B2, and Co-Cr clasps with design A2 had higher retentive forces than those of the control group. SLM-built CP Ti and Ti-6Al-4V clasps with design A1 had lower retentive forces than those of the control group. SLM-built Co-Cr clasp with design A1 and SLM-built CP Ti and Ti-6Al-4V clasps with design A2 had equivalent retentive forces to those of the control group. The insertion/removal experiment showed that the measured retentive forces of these three groups of SLM-built clasps were (21.57±5.41) N, (19.75±4.47) N, and (19.32±2.04) N, respectively. No statistically significant measured retentive force difference was found among these three groups of SLM-built clasps (P>0.05). The maximum von Mises stress of these three groups of SLM-built clasps exceeded their responding yield strength except for the Ti-6Al-4V one. CONCLUSION: SLM-built Co-Cr circumferential clasps had higher retention than CP Ti and Ti-6Al-4V ones with the same clasp arm size and undercut engagement. The retention of SLM-built circumferential clasps could be adjusted by changing the undercut engagement and clasp arm size. If SLM-built circumferential clasps are used in clinical practice, the Ti-6Al-4V clasp with clasp arm size A and 0.50 mm undercut engagement is recommended considering the long-term use of RPD in the patient's mouth.

[Comparison and thoughts of the training system for thoracic surgeons].

There is no unified thoracic surgery training system in China, neither in the trainee selection or evaluation, nor in the training curriculum or the graduation requirements. A literature review was performed for available publications regarding international thoracic surgical training. A brief comparison was made regarding the thoracic surgery residency programs in China, Japan, United States and United Kingdom, including training pathway, recruitments, training content, performance assessment and academic experience. In conclusion, there are four key aspects worth noting. Firstly, an effective residency programme is invaluable to specialty training, and effort should be made to create a unified training programme that allows trainee to progress from residency to specialty training smoothly. Secondly, flexibility and personalization should be allowed in higher specialty training, so that trainee can develop their subspecialty interests. Thirdly, a unified clinical curriculum, selection and standardized income should be promoted to minimalize the variation of training outcome between provinces. Fourthly, additional training and time should be allowed for trainee who wants to pursue an academic career, and academic outcomes should be evaluated alongside with the standard clinical training.

[Association between the presence of solid or micropapillary components and survival outcome in stage â A lung adenocarcinoma cases: a retrospective cohort study].

Objectives: To examine the influence of the proportion of pathological subtypes on the prognosis of stage ⅠA lung adenocarcinoma cases, and to explore the association between the presence/absence of solid or micropapillary (S/M) components and survival outcome. Methods: Totally 321 patients with stage ⅠA lung adenocarcinoma who received complete surgical resection at Department of Thoracic Surgery, Tongji University Affiliated Shanghai Pulmonary Hospital from January 2011 to December 2013 were retrospectively analyzed. There were 130 males and 191 females, aging 59(11) years (M(IQR)) (range: 55 to 66 years). The diagnostic value of the proportion of each pathological growth subtype on relapse-free survival (RFS) and overall survival (OS) were analyzed by using receiver operator characteristic curve. Patients were firstly divided into two groups according to the presence or absence of S/M components. And patients without S/M components were farther divided into two groups according to predominant growth pattern. There were three groups in total: with S/M components (group S/M+), without S/M components and lepidic growth pattern predominant (group S/M-LPA), without S/M components and papillary or acinar growth pattern predominant (group S/M-P/A). Kaplan-Meier method were used to draw the survival curves of the three groups, and Log-rank test were used to compare RFS and OS among the three groups. Cox proportional risk model was used to verify whether the presence of S/M components was a prognostic factor on RFS. Results: The proportion of S/M components had no diagnostic value for recurrence (solid: area under curve (AUC)=0.588, P=0.095; micropapillary: AUC=0.566, P=0.106) and death (AUC=0.589, P=0.104; AUC=0.607, P=0.056). The 5-year RFS rate of group S/M-LPA, S/M-P/A and S/M+ were 92.4%, 82.3% and 77.3%, respectively (all P<0.05), while the 5-year OS rate were 97.4%, 94.5% and 83.2%, respectively (all P<0.05). Multivariable analysis showed that the 3 groups were independent predictors of recurrence (S/M-P/A vs. S/M- LPA: HR=2.691, 95%CI: 1.249 to 5.799, P=0.011; S/M+ vs. S/M-LPA, HR=6.763, 95%CI: 3.050 to 14.996, P<0.01). Conclusions: The proportion of S/M components in stage ⅠA lung adenocarcinoma with complete resection cases did not affect survival outcome. New grouping method based on the presence or absence of S/M components were significantly associated with patient survival outcomes: S/M+ patients had the worst prognosis and S/M-LPA patients had the best prognosis.

Revisiting the basic theory of sum-frequency generation.

The basic theory of sum-frequency generation (SFG) is revisited. A rigorous derivation showing that linear optical transmission and reflection at an interface result from the interference of the incident wave and induced radiation wave in a medium is presented. The derivation is extended to SFG in a medium with a finite interface layer to see how SFG evolves. Detailed description on interface vs bulk and electric dipole (ED) vs electric quadrupole (EQ) contribution to SFG are provided with essentially no model dependence, putting the theory of SFG on a solid ground and removing possible existing confusions. Electric-quadrupole contributions to SFG from the interface and bulk are discussed. It is seen that there is a relevant bulk EQ contribution intrinsically inseparable in measurement from the interface ED contribution but plays a major role among all EQ contributions; its importance relative to the ED part can only be judged by referring to the established reference cases.

Enhancement of femtosecond surface nonlinear optical signals with spatiotemporal focusing.

Nonlinear optical reflection spectroscopies for surface studies often suffer from their relatively weak signals. To enhance the signal strength, femtosecond input pulses are generally preferred, but their intensity is usually limited by supercontinuum (SC) generation in a bulk medium. We show here that the problem can be largely resolved by means of spatiotemporal focusing (STF) of the input that effectively suppresses the SC, permits much higher input intensity on a medium, and greatly enhances the nonlinear output signal. We use second-harmonic generation (SHG) on oxide as examples and demonstrate that, with STF, the input intensity for the onset of the SC can be increased by ∼30 times in comparison with conventional focusing, and the reflected SHG can be increased by about three orders of magnitude.

Polymer Adsorption on Graphite and CVD Graphene Surfaces Studied by Surface-Specific Vibrational Spectroscopy.

Sum-frequency vibrational spectroscopy was employed to probe polymer contaminants on chemical vapor deposition (CVD) graphene and to study alkane and polyethylene (PE) adsorption on graphite. In comparing the spectra from the two surfaces, it was found that the contaminants on CVD graphene must be long-chain alkane or PE-like molecules. PE adsorption from solution on the honeycomb surface results in a self-assembled ordered monolayer with the C-C skeleton plane perpendicular to the surface and an adsorption free energy of ∼42 kJ/mol for PE(H(CH2CH2)nH) with n ≈ 60. Such large adsorption energy is responsible for the easy contamination of CVD graphene by impurity in the polymer during standard transfer processes. Contamination can be minimized with the use of purified polymers free of PE-like impurities.

Phase-sensitive sum-frequency spectroscopy.

Phase-sensitive sum-frequency spectroscopy (SFS) allows the complete measurement of the complex spectra of surface nonlinear response coefficients. Similar to linear spectroscopy, the spectrum of the imaginary part of a surface response coefficient directly characterizes surface resonances without complication. This newly developed technique has greatly enhanced the capability of surface SFS and provides many new research opportunities for surface science. This article describes the experimental schemes and underlying theory for the technique and briefly reviews works that have clearly demonstrated its power.

Safety evaluation of phytosterols in laying hens: effects on laying performance, clinical blood parameters, and organ development.

Phytosterols are intended for use as a novel food ingredient with plasma cholesterol-lowering activity. Although phytosterols are naturally present in the normal diet, daily consumption is insufficient to ensure plasma cholesterol-lowering levels. Therefore, phytosterols may be added to the diets to achieve the desired cholesterol-lowering activity. A subchronic laying hen safety study was conducted to examine if high-dose phytosterols could affect the safety of hens. Three hundred sixty 21-wk-old Hy-Line Brown laying hens were randomly assigned to 5 groups with 6 replicates of 12 birds each; after 3 wk, birds were fed diets supplemented with 0, 20, 80, 400, and 800 mg/kg of phytosterols for 12 wk. Throughout the study, clinical observations and laying performance were measured. At the end of the study, birds were subjected to a full postmortem examination: blood samples were taken for clinical pathology, selected organs were weighed, and specified tissues were taken for subsequent histological examination. No treatment-related changes that were considered to be of toxicological significance were observed. Therefore, a nominal phytosterol concentration of 800 mg/kg was considered to be the no-observed-adverse-effect level.

The generation of genuine quadripartite Einstein-Podolsky-Rosen steering in an optical superlattice.

Einstein-Podolsky-Rosen (EPR) steering is a quantum effect based on quantum entanglement and it is the key resource for building quantum networks because of its useful properties. Based on the criterion for genuine multipartite EPR steering, the genuine quadripartite EPR steering is confirmed and it can be generated by a spontaneous parametric down-conversion cascaded process with two sum-frequency generations in an optical superlattice. This occurs either below the oscillation threshold and without oscillation threshold. The influence of the parameters of cascaded nonlinear process on the quadripartite EPR steering among signal, idler, and two sum-frequency beams are also discussed. Choosing appropriate nonlinear parameters can achieve good quadripartite quantum steering. This scheme of the generation of genuine quadripartite EPR steering has potential applications in quantum communication and computing.

Optical control of surface anchoring and reorientation of liquid crystals via a plasmon-enhanced local field.

Gold nanoparticles deposited on the windows of a liquid crystal (LC) cell were found to be able to reduce the surface anchoring energy of the LC, and hence the threshold for its reorientation phase transition, by 1 to 2 orders of magnitude when a cw pump light was used to excite the local plasmon resonance of the nanoparticles. The effect was due to the disorientation of LC molecules between nanoparticles by the plasmon-enhanced local field that softens the effective surface anchoring. A light-controlled variation of surface anchoring energy could provide new opportunities for optoelectronic applications of a LC.

Structure and charging of hydrophobic material/water interfaces studied by phase-sensitive sum-frequency vibrational spectroscopy.

We have studied the hydrophobic water/octadecyltrichlorosilane (OTS) interface by using the phase-sensitive sum-frequency vibrational spectroscopy (PS-SFVS), and we obtained detailed structural information of the interface at the molecular level. Excess ions emerging at the interface were detected by changes of the surface vibrational spectrum induced by the surface field created by the excess ions. Both hydronium (H(3)O(+)) and hydroxide (OH(-)) ions were found to adsorb at the interface, and so did other negative ions such as Cl(-). By varying the ion concentrations in the bulk water, their adsorption isotherms were measured. It was seen that among the three, OH(-) has the highest adsorption energy, and H(3)O(+) has the lowest; OH(-) also has the highest saturation coverage, and Cl(-) has the lowest. The result shows that even the neat water/OTS interface is not neutral, but charged with OH(-) ions. The result also explains the surprising observation that the isoelectric point appeared at approximately 3.0 when HCl was used to decrease the pH starting from neat water.

Intrinsic optical properties of vanadium dioxide near the insulator-metal transition.

We studied the insulator-metal transition (IMT) in single-domain, single crystalline vanadium dioxide (VO(2)) microbeams with infrared microspectroscopy. The unique nature of such samples allowed us to probe the intrinsic behavior of both insulating and metallic phases in the close vicinity of IMT, and investigate the IMT driven by either strain or temperature independently. We found that the VO(2) insulating band gap narrows rapidly upon heating, and the infrared response undergoes an abrupt transition at both strain- and temperature-induced IMT. The results are consistent with recent studies attributing the opening of VO(2) insulating band gap to a correlation-assisted Peierls transition.

[Analysis of relationship between distribution of pathogenic microorganisms in olfactory cleft and olfactory disorders among patients with upper respiratory inflammation during the prevention and control of COVID-19].

Objective: To explore the relationship between pathogens in the olfactory cleft area and olfactory disorders in patients with upper respiratory inflammation (URI) during the prevention and control of 2019 novel coronavirus disease (COVID-19). Methods: A total of 234 URI patients including acute upper respiratory infection, chronic rhinosinusitis (CRS), allergic rhinitis (AR) were continuously selected from September 2020 to March 2021 in Beijing Anzhen Hospital and 98 healthy adults were enrolled as controls. The secretions from the olfactory cleft of all subjects were collected with nasal swabs under nasal endoscopy. Multiple real-time fluorescent quantitative polymerase chain reaction detection method was used to detect nucleic acids of 33 types of respiratory pathogenic microorganism. Sniffin' Sticks olfactory test was performed on all patients with URI. URI patients with olfactory dysfunction were followed up for 9 (8, 10) months (M (Q1, Q3)). SPSS 20.0 software was used for statistical analysis. Results: Among the 98 controls, 9 (9.18%) were positive for pathogenic microorganisms, including 1 (1.02%) rhinovirus, 1 (1.02%) parainfluenza virus type 3, 3 (3.06%) enterovirus, 1 (1.02%) staphylococcus aureus and 3 (3.06%) Moraxella catarrhalis. Among the 234 URI patients, 111 (47.44%) had olfactory disorders and 123 (52.56%) had normal sense of smell. In the olfactory disorder group (111 cases), 38 cases (34.23%) were positive for pathogenic microorganisms, and 4 cases (3.60%) were mixed infection, including 11 cases of rhinovirus (9.91%), 5 cases of coronavirus 229E (4.50%), 2 cases of coronavirus OC43/NL63 (1.80%), 3 cases of parainfluenza virus type 1 (2.70%), 2 cases of enterovirus (1.80%), 1 case of influenza B virus type BV (0.90%), 11 cases of Staphylococcus aureus (9.91%), 7 cases of Moraxella catarrhalis (6.31%), and 1 case of Klebsiella pneumoniae (0.90%). In the normal smell group (123 cases), 18 cases (14.63%) were positive for pathogenic microorganisms, and 1 case (0.81%) was mixed infection, including 3 cases of rhinovirus (2.44%), 4 cases of coronavirus 229E (3.25%), 1 case of Influenza virus type 3 (0.81%), 3 cases of enterovirus (2.44%), 3 cases of Staphylococcus aureus (2.44%), 4 cases of Moraxella catarrhalis (3.25%), and 1 case of Klebsiella pneumoniae (0.81%). Univariate analysis between the two groups found that there were significant differences in the detection rate of pathogenic microorganisms, rhinovirus and Staphylococcus aureus between the groups (all P<0.05). The detection rate of parainfluenza virus type 1, Staphylococcus aureus, and rhinovirus were different between the patients with olfactory disorder and normal olfactory function in the three subgroups of acute upper respiratory tract infection, CRS and AR, respectively (χ2 value was 3.88, 4.53 and 4.73, respectively, all P<0.05). During the follow-up period, among the 111 patients with olfactory disorder, 71 (63.96%) patients' olfactory function returned to normal, 32 (28.83%) patients' olfactory function improved but not completely returned to normal, 8 (7.21%) patients' olfactory function did not improve. Conclusions: During the prevention and control of COVID-19, rhinovirus or Staphylococcus aureus infection or colonization of URI patients is closely related to olfactory disorders. Parainfluenza virus type 1 infection can cause relatively persistent olfactory disorders in patients with acute upper respiratory tract infection. Staphylococcus aureus and rhinovirus colonization are related to the occurrence of olfactory dysfunction in CRS and AR patients respectively.

[Quantitative evaluation of printing accuracy of multi-color and multi-hardness three-dimensional printing dental model with photopolymer jetting].

Objective: To quantitatively evaluate the accuracy of multi-color and multi-hardness dental models printed by using the photopolymer jetting (PJ) technology, and to provide protocol for the clinical application. Methods: A maxillary partially edentulous (Kennedy class Ⅱ subclass 1) standard digital model obtained through scanning and processing was selected as reference data. Five monochromatic DLP (digital light processing) models with single hardness were printed by printer DLP-800d based on DLP technology (DLP group), and five multi-color and multi-hardness PJ models were printed by printer J300Plus based on PJ technology (PJ group). Scan the printed model and register the scanning data to the reference data in Geomagic Studio 2013 software. The three-dimensional (3D) deviations of the whole and each area, including residual dentition, abutments adjacent to the edentulous area, gingiva, gingiva in the distal-extended edentulous area, gingiva in other edentulous areas, gingiva supporting the removable partial denture (RPD), were calculated and represented by the root mean square error (RMS) value. The smaller the RMS value was, the higher the trueness of printing was. The scanning data of the five models in the same group were registered in pairs to calculate the 3D deviation. The smaller the RMS value was, the higher the precision of printing was. The threshold of clinical acceptability was 200 µm. Statistical analysis was performed to compare the difference of trueness and precision between the two groups. Results: The overall trueness of the DLP group [57.70 (2.10) µm] was significantly better than that of the PJ group [71.00 (7.70) µm]. The overall precision of the DLP group [15.20 (5.05) µm] was significantly better than that of the PJ group [37.55 (15.55) µm]. The overall trueness and precision of both groups were within the clinically acceptable range. Conclusions: The domestic PJ printer used in this study can print multi-color and multi-hardness dental models with good trueness and precision, which can provide integrated 3D printing technology support for realizing the simulation of regional hardness differentiation between soft and hard tissues of dental models.

Sum-frequency spectroscopic study of Langmuir monolayers of lipids having oppositely charged headgroups.

Sum-frequency vibrational spectroscopy, with the help of surface pressure-area (π-A) isotherm, was used to study lipid Langmuir monolayers composed of molecules with positively and negatively charged headgroups as well as a 1:1 neutral mixture of the two. The spectral profiles of the CH(x) stretch vibrations are similar for all monolayers in the liquid-condensed (LC) phase. They suggest a monolayer structure of closely packed alkyl chains that are nearly all-trans and well oriented along the surface normal. In the liquid-expanded (LE) phase, the spectra of all monolayers appear characteristic of loosely packed chains with significant gauche defects. The OH stretch spectra of interfacial water for both positively and negatively charged monolayers are significantly enhanced in comparison with a neutral water interface, but the phase measurement of SFVS indicates that OH in the two cases points toward the bulk and the interface, respectively. The enhancement results mainly from surface-field-induced polar ordering of interfacial water molecules. For a charge-neutral monolayer composed of an equal number of positively and negatively charged lipid molecules, no such enhancement is observed. This mixed monolayer exhibits a wide range of LC/LE coexistence region extended to very low surface pressure and its CH(x) spectral profile in the coexistence region resembles that of the LC phase. This result suggests that in the LC/LE coexistence region, the mixed monolayer consists of coexisting LC and LE patches in which oppositely charged lipid molecules are homogeneously mixed and dispersed.

Surface vibrational spectroscopic studies of hydrogen bonding and hydrophobicity.

Surface vibrational spectroscopy by sum-frequency generation was used to study hydrophobicity at the molecular level at various interfaces: water-surfactant-coated quartz, water-hexane, and water-air. In all cases, hydrophobicity was characterized by the appearance of dangling hydroxyl bonds on 25 percent of the surface water molecules. At the water-quartz interface, packing restrictions force the water surface layer to have a more ordered, ice-like structure. A partly wettable water-quartz interface was also studied.

The dietary combination of essential oils and organic acids reduces Salmonella enteritidis in challenged chicks.

This study was conducted to determine the effects of essential oils and organic acids (EOA) on Salmonella Enteritidis (S. Enteritidis) challenged chickens. One-day-old specific pathogen-free (SPF) chicks (250) were randomly assigned to 5 groups, with 50 birds in each group. The treatment groups were as follows: 1) basal diet, negative control group (NC); 2) basal diet + S. Enteritidis, positive control group (PC); 3) PC + 4,000 g/t of enrofloxacin (5%), antibiotic group (ENR); 4) PC + 800 g/t of EOA1, thymol-benzoic acid group (TBA); and 5) PC + 800 g/t of EOA2, cinnamylaldehyde-caproic acid group (CCA). At 7 D of age, each bird, except those in NC, was orally gavaged with 0.4 mL of a suspension of 4.4 × 109 cfu S. Enteritidis/mL. Results revealed that ENR reduced bacterial counts in the liver and spleen on days 3, 5, and 7 post-challenge more (P < 0.05) than any other treatments. However, bacterial counts in cecal contents among ENR, TBA, and CCA were similar at 5 and 7 D post-challenge but lower than those of PC. Additionally, the bacterial counts in liver, spleen, and cecum contents in TBA were lower (P < 0.05) than in PC at 3, 5, and 7 D post-challenge; the bacterial counts in spleen contents in TBA were lower (P < 0.05) than in CCA at 7 D post-challenge. Tumor necrosis factor-α contents in TBA and CCA were lower (P < 0.05) than those in PC. Also, the ratio of villus height to crypt depth in the ileum of CCA was higher (P < 0.05) than that of PC and ENR; however, there was no difference in the secretory IgA content of the jejunum among the groups. In conclusion, EOA had a bacteriostatic effect on S. Enteritidis, and the effect of the thymol-benzoic acid complex surpassed that of the cinnamaldehyde-caproic acid complex. Therefore, EOA may act as an effective antibiotic substitute for animals in the prevention and treatment of Salmonella.

Dynamics of the guest-host orientational interaction in dye-doped liquid-crystalline materials.

We present a comprehensive study on the dynamics of laser-induced molecular reorientation in a dye-doped liquid crystalline (LC) medium that exhibits significant enhancement of the optical Kerr nonlinearity due to guest-host interaction. Using various techniques, we separately characterized the dynamical responses of the relevant molecular species present in the medium following photoexcitation and, thus, were able to follow the transient process in which photoexcitation of the dye molecules exert through guest-host interaction a net torque on the host LC material, leading to the observed enhanced optical Kerr nonlinearity. Experimental results agree quantitatively with the time-dependent theory based on a mean-field model of the guest-host interaction.

Orientations of side chains and adsorbed liquid crystal molecules on a rubbed polyimide surface studied by optical second harmonic generation.

Surface second harmonic generation was used to obtain approximate orientational distributions of the side chains and the adsorbed liquid crystal (LC) molecules on a rubbed side-chain polyimide surface. Both the side chains and the LC molecules appear to be well aligned in the rubbing direction but tilted away from the surface in the antirubbing direction. The latter yields a negative pretilt angle in a homogeneously aligned LC film sandwiched between two such surfaces. The side chains and the LC molecules, however, have antiparallel orientations at the surface.