Multiphoton Ionization/Dissociation of Molecular Sulfur S2 in the UV Region.

The multiphoton ionization/dissociation dynamics of molecular sulfur (S2) in the ultraviolet range of 205-300 nm is studied using velocity map ion imaging (VMI). In this one-color experiment, molecular sulfur (S2) is generated in a pulsed discharge and then photodissociated by UV radiation. At the three-photon level, superexcited states are accessed via two different resonant states: the B3Σu- (v' = 8-11) valence states at the one-photon level and a Rydberg state at the two-photon level. Among the decay processes of these superexcited states, dissociation to electronically excited S atoms is dominant as compared to autoionization to ionic states S2+ (X2Πg) at wavelengths λ < 288 nm. The anisotropy parameter extracted from these images reflects the parallel character of these electronic transitions. In contrast, autoionization is found to be particularly efficient at S(1D) and S(1S) detection wavelengths around 288 nm. Information obtained from the kinetic energy distributions of S atoms has revealed the existence of vibrationally excited S2+ (X2Πg (v+ > 11)) that dissociates to ionic products following one-photon absorption. This work also reveals many interesting features of S2 photodynamics compared to those of electronically analogous O2.

Saikosaponin d modulates the polarization of tumor-associated macrophages by deactivating the PI3K/AKT/mTOR pathway in murine models of pancreatic cancer.

The tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) poses a major obstacle to traditional and immunomodulatory cancer therapies and is closely associated with macrophage polarization. Saikosaponin d (SSd), a major active component of triterpene saponins derived from Bupleurum falcatum, has anti-inflammatory and antitumor activities. However, whether SSd can regulate immune cells during the development of the TME in PDAC remains unknown. In the present study, we aimed to analyze the role of SSd in regulating immune cells in the PDAC TME, especially the polarization of macrophages, and examine the related mechanisms. An orthotopic PDAC cancer model was used to investigate the antitumor activities and the regulation of immune cells in vivo. In vitro, bone marrow mononuclear (BM-MNC) cells and RAW 264.7 cells were used to induce the M2 macrophage phenotype and examine the effects and molecular mechanism of SSd on M2 macrophage polarization. The results revealed that SSd could directly inhibit the apoptosis and invasion of pancreatic cancer cells, modulate the immunosuppressive microenvironment and reactivate the local immune response, especially by decreasing the shift toward M2 macrophage polarization by downregulating phosphorylated STAT6 levels and the PI3K/AKT/mTOR signaling pathway. Furthermore, 740-Y-P (PI3K activator) was used to verify that SSd inhibited M2 polarization in RAW264.7 cells via the PI3K/AKT/mTOR signaling pathway. In conclusion, this study provided experimental evidence of the antitumor effect of SSd, especially in the regulation of M2 macrophage polarization, and demonstrated that SSd may be a promising therapeutic agent in PDAC.

A Phase Field Approach to Two-Dimensional Quasicrystals with Mixed Mode Cracks.

Quasicrystals (QCs) are representatives of a novel kind of material exhibiting a large number of remarkable specific properties. However, QCs are usually brittle, and crack propagation inevitably occurs in such materials. Therefore, it is of great significance to study the crack growth behaviors in QCs. In this work, the crack propagation of two-dimensional (2D) decagonal QCs is investigated by a fracture phase field method. In this method, a phase field variable is introduced to evaluate the damage of QCs near the crack. Thus, the crack topology is described by the phase field variable and its gradient. In this manner, it is unnecessary to track the crack tip, and therefore remeshing is avoided during the crack propagation. In the numerical examples, the crack propagation paths of 2D QCs are simulated by the proposed method, and the effects of the phason field on the crack growth behaviors of QCs are studied in detail. Furthermore, the interaction of the double cracks in QCs is also discussed.

Photosensitive damage of dipeptides: mechanism and influence of structure.

We illustrate the influence of the dipeptide structure on photosensitive damage and the kinetic mechanism was investigated using acenaphthenequinone (ACQ) as a triplet photosensitizer. With tyrosine (Tyr) serving as the core structure, two classic dipeptides with double (trptophan-tyrosine, Trp-Tyr) and single (tyrosine-alanine, Tyr-Ala and Ala-Tyr) active reaction sites were constructed, and the underlying photodamage mechanisms were investigated carefully. According to the experimental results, the proton-coupled electron transfer processes between ACQ and numerous Trp-Tyr reaction sites have independent reaction properties. The bimolecular quenching rate (kq) value is roughly equivalent to the sum of the rates of two amino acid monomers, and a novel intramolecular dynamic channel between Trp/N˙-Tyr and Trp-Tyr/O˙ was observed. The ACQ/Tyr-Ala system demonstrated the key role of steric hindrance on the kq in bimolecular reactions.

Numerical Simulation and Experimental Study on Energy Absorption of Foam-Filled Local Nanocrystallized Thin-Walled Tubes under Axial Crushing.

A crashworthiness design of foam-filled local nanocrystallized thin-walled tubes (FLNTs) is proposed by using foam-filled structures and ultrasonic impact surface treatment. The crashworthiness and deformation modes of FLNTs are studied using an experiment and numerical analysis. A finite element numerical model of FLNTs is established, and the processing and test platform of FLNTs is set up to verify the numerical predication and analytical design. The results show that local nanocrystallization is an effective method to enhance crashworthiness for hexagonal FLNTs. The FLNTs with four circumferential continuous stripes of surface nanocrystallization exhibit a level of 47.12% higher specific energy absorption than the untreated tubes in numerical simulations for tubes with a 50% ratio of nanocrystallized area. Inspired by the strength mechanism, a novel nested foam-filled local surface nanocrystallization tube is further designed and studied in detail.

Investigation on the photoinduced chemical reaction between p-benzoquinone and tryptophan in homogeneous solution.

Photoinduced electron transfer (PET) and energy transfer between amino acids and bioquinones have become research hotspots, due to the important roles they play in a physiological environment. However, as classic benzoquinones and amino acids, the reaction mechanism of p-benzoquinone (PBQ) and tryptophan (Trp) is still unclear. In this work, the photoinduced chemical reaction of PBQ and Trp was investigated in homogeneous solution using time-resolved electron paramagnetic resonance and laser flash photolysis techniques. Under photoexcitation at 355 nm, the 3PBQ* produced via intersystem crossing (ISC) in ethylene glycol aqueous (EG-H2O) solution followed by the H-atom transfer (HAT) from EG to 3PBQ* was a significant process in competition with the non-radiative transition of 3PBQ*, which was clearly observed in the transient absorption spectra and chemically induced dynamic electron polarization spectra. When Trp was added into the PBQ/EG-H2O solution, a new decay channel of 3PBQ* was produced that reacted with Trp to form a p-benzoquinone anion radical (PBQ˙-) and a tryptophan cationic radical (Trp˙+), indicating that the photoinduced chemical reaction mechanism was the electron transfer. By fitting the decay dynamic curves, the quenching rate constant of 3PBQ* to Trp in homogeneous solution was determined as 6.8 × 108 M-1 s-1, which was close to the diffusion-controlled rate.

A finite element analysis study based on valgus impacted femoral neck fracture under diverse stances.

The aim of the study was to determine the biomechanical environment of patients who suffer from valgus impacted femoral neck fracture. With the help of computational modeling, both of finite element hip fracture and normal three-dimensional model were reconstructed from a patient with hip fracture. The predicted stress distribution was compared between before and after fracture. After the fracture, during standing and the gait, the fracture site has a greater change in stress distribution due to the shortening of the femoral neck. The largest stress occurs at the middle and lower end of the femoral shaft, which occurs from toe off to deceleration during the whole gait. After the fracture, greater stress on the femoral head will result in a worse mechanical environment for the femur. The stress peak value of the femoral shaft is larger than the unfractured side and the stress distribution is uneven. From the results of gait analysis, it is concluded that the increase of concentrated stress and the change of stress distribution will cause the possibility of secondary fractures at the middle and lower ends of the femoral shaft when there is an accident in the case of existing fracture.

Design and Optimization of a New Anti-reflux Biliary Stent With Retractable Bionic Valve Based on Fluid-Structure Interaction Analysis.

Duodenal biliary reflux has been a challenging common problem which could cause dreadful complications after biliary stent implantation. A novel anti-reflux biliary stent with a retractable bionic valve was proposed according to the concertina motion characteristics of annelids. A 2D equivalent fluid-structure interaction (FSI) model based on the axial section was established to analyze and evaluate the mechanical performances of the anti-reflux biliary stent. Based on this model, four key parameters (initial shear modulus of material, thickness, pitch, and width) were selected to investigate the influence of design parameters on anti-reflux performance via an orthogonal design to optimize the stent. The results of FSI analysis showed that the retrograde closure ratio of the retractable valve primarily depended on initial shear modulus of material (p < 0.05) but not mainly depended on the thickness, pitch, and width of the valve (p > 0.05). The optimal structure of the valve was finally proposed with a high retrograde closing ratio of 95.89%. The finite element model revealed that the optimized anti-reflux stent possessed improved radial mechanical performance and nearly equal flexibility compared with the ordinary stent without a valve. Both the FSI model and experimental measurement indicated that the newly designed stent had superior anti-reflux performance, effectively preventing the duodenobiliary reflux while enabling the bile to pass smoothly. In addition, the developed 2D equivalent FSI model provides tremendous significance for resolving the fluid-structure coupled problem of evolution solid with large deformation and markedly shortens the calculation time.

Efficient Triplet-Triplet Annihilation Upconversion in Solution and Hydrogel Enabled by an S-T Absorption Os(II) Complex Dyad with an Elongated Triplet Lifetime.

A new Os(II) complex dyad featuring direct singlet-to-triplet (S-T) absorption and intramolecular triplet energy transfer (ITET) with lifetime up to 7.0 µs was designed to enhance triplet energy transfer efficiency during triplet-triplet annihilation upconversion (TTA-UC). By pairing with 9,10-bis(phenylethynyl)anthracene (BPEA) as a triplet acceptor, intense upconverted green emission in deaerated solution was observed with unprecedented TTA-UC emission efficiency up to 26.3% (with a theoretical maximum efficiency of 100%) under photoexcitation in the first biological transparency window (650-900 nm). Meanwhile, a 7.1% TTA-UC emission efficiency was acquired in an air-saturated hydrogel containing the photosensitizer and a newly designed hydrophilic BPEA derivative. This ITET mechanism would inspire further development of a highly efficient TTA-UC system for biological fields and renewable energy production.

Design of bionic active-passive hybrid-driven prosthesis based on gait analysis and simulation of compound control method.

PURPOSE: The purpose of this paper is to design a prosthetic limb that is close to the motion characteristics of the normal human ankle joint. METHODS: In this study, combined with gait experiments, based on a dynamic ankle joint prosthesis, an active-passive hybrid-driven prosthesis was designed. On this basis, a real-time control algorithm based on the feedforward compensation angle outer loop is proposed. To test the effectiveness of the control method, a multi-body dynamic model and a controller model of the prosthesis were established, and a co-simulation study was carried out. RESULTS: A real-time control algorithm based on the feedforward compensation angle outer loop can effectively realize the gait angle curve measured in the gait test, and the error is less than the threshold. The co-simulation result and the test result have a high close rate, which reflects the real-time nature of the control algorithm. The use of parallel springs can improve the energy efficiency of the prosthetic system. CONCLUSIONS: Based on the motion characteristics of human ankle joint prostheses, this research has completed an effective and feasible design of active and passive ankle joint prostheses. The use of control algorithms improves the controllability of the active and passive ankle joint prostheses.

Multi-photon absorption organotin complex for bioimaging and promoting ROS generation.

Compared to general fluorescent dyes, multi-photon fluorescent dyes exhibit deeper tissue penetration and lower auto-fluorescence in the bio-imaging field. Therefore, it is necessary to develop an efficient multiphoton imaging agent for deep tissue imaging. In this work, an organotin derivative (HSnBu3) has been designed and synthesized, which shows multiphoton absorption activity. In constrast to the ignorable three-photon activity of the ligand, the complex (HSnBu3) exhibits three-photon activity under NIR excitation (1500 nm). Results of chemical and biological tests confirmed that HSnBu3 was more easily activated by oxygen resulting in a higher level of 1O2, which could induce a decrease in mitochondrial membrane potential in HepG2 cells. It suggests that HSnBu3 has potential in photodynamic therapy.

A three-dimensional measurement based on CT for the posterior tilt with ideal inter-and intra-observer reliability in non-displaced femoral neck fractures.

Posterior tilt is associated with prognosis of non-displaced femoral neck fractures (FNFs). Knowledge of their association is critical and informs surgeons whether to choose internal fixation or arthroplasty in treatment of non-displaced FNFs. This study aimed to design a novel three-dimensional (3D) posterior tilt measurement and evaluate the intra- and inter-observer variability compared to two-dimensional (2D) measurement proposed by Palm. We hypothesized that 3D measurement would be more accurate and realistic with higher reliability. To test the hypothesis, three observers measured the posterior tilt on the radiographs of 50 non-displaced FNFs, twice with both methods. Intra- and inter-observer reliability for each measurement method used were determined. The measured angle was divided into two categories, at the cut-off of 20° for clinical practice simulation. Intra- and inter-observer reliability were identified for clinical effectiveness. The results indicated that inter- and intra-observer reliability for 3D measurement and its classification was almost perfect with an intraclass coefficient of 0.995 (0.994) and a kappa value of 0.927(0.947), respectively. Conversely, a substantial inter- and intra-observer reliability for the 2D measurement was obtained with an interclass coefficient of 0.764 as well as an intraclass coefficient of 0.773. The clinical validity for 2D measurement showed slight inter-reliability and moderate intra-reliability with a kappa value of 0.192 and 0.587, respectively. Hence, the novel 3D measurement appears to be more reliable with a strong inter- and intra-observer reliability measurement. Further clinical studies are needed to carry out to validate this hypothesis.

Design and evaluation of a novel anti-reflux biliary stent with cone spiral valve.

Endoscopic placement of biliary stent is a well-established palliative treatment for biliary obstruction. However, duodenobiliary reflux after stent placement has been a common problem which may lead to dreadful complications. This paper designed a novel anti-reflux biliary stent with a cone spiral valve. Fluid-Structure Interaction (FSI) simulations were established to evaluate the efficiency of the anti-reflux stent comparing with a clinically applied standard stent. According to the stress distribution of the valve, the fatigue performance in the stress concentration area was analyzed. The results show that when the antegrade flow through the valve, the cone spiral valve could stretch and open to realize adequate drainage under the normal physiological pressure of biliary tract; When the duodenal reflux through the valve, the valve would be compressed and close with a result of nearly zero at the outlet flow rate. Furthermore, the anti-reflux stent achieved improved radial mechanical performance with 2.7 times higher radial stiffness than standard stent. Finite element analysis (FEA) also indicates that compared with the standard stent, the addition of the anti-reflux valve had little negative effect on flexibility of the stent. Fatigue analysis results showed that the valve was reliable. This research provides the new stent with a cone spiral valve and proves that it is technically feasible and effective for preventing the duodenobiliary reflux while ensuring the antegrade bile flow without compromising the other biomechanical performances.

Post-buckling analysis of functionally graded multilayer graphene platelet reinforced composite cylindrical shells under axial compression.

Axially compressed composite cylindrical shells can attain multiple bifurcation points in their post-buckling procedure because of the natural transverse deformation restraint provided by their geometry. In this paper, the post-buckling analysis of functionally graded (FG) multilayer graphene platelets reinforced composite (GPLRC) cylindrical shells under axial compression is carried out to investigate the stability of such shells. Rather than the critical buckling limit, the focus of the present study is to obtain convergence post-buckling response curves of axially compressed FG multilayer GPLRC cylindrical shells. By introducing a unified shell theory, the nonlinear large deflection governing equations for post-buckling of FG multilayer GPLRC cylindrical shells with wide range of thickness are established, which can be easily changed into three widely used shell theories. Load-shortening curves for both symmetric and asymmetric post-buckling modes are obtained by Galerkin's method. Numerical results illustrate that the present solutions agree well with the existing theoretical and experimental data. The effects of geometries and material properties on the post-buckling behaviours of FG multilayer GPLRC cylindrical shells are investigated. The differences in the three shell theories and their scopes are discussed also.

PEDF improves atherosclerotic plaque stability by inhibiting macrophage inflammation response.

BACKGROUND: Atherosclerosis is a vascular disease with plaque formation and growth. Instable plaque with chronic inflammation is closely related to adverse cardiac outcomes. Pigment epithelium-derived factor (PEDF) is an endogenous multifunctional cytokine that possesses the ability of anti-inflammation. The aim of this study is to detect whether PEDF has protective effect on the stability of atherosclerotic plaque and to explore whether the effect of anti-inflammation involved. METHODS AND RESULTS: ApoE-/- mice fed with high fat diet and RAW264.7 cells were used to evaluate anti-inflammatory activities of PEDF both in vivo and in vitro. PEDF overexpression improved atherosclerotic plaque stability in ApoE-/- mice. The expression of inflammatory factors (interleukin-1ß [IL-1ß], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α], monocyte chemotactic protein-1 [MCP-1] and matrix metalloproteinase [MMP-9]) was significantly decreased with PEDF overexpression in vivo and in vitro. The anti-inflammation effect of PEDF was attenuated by PPAR-γ specific antagonist GW9662. In addition, PEDF significantly decreased the expression of phosphorylated ERK-MAPK, p38-MAPK and JNK-MAPK. GW9662 partly reversed the PEDF-mediated depression of phosphorylated ERK- and p38-MAPK but has no significant effect on JNK-MAPK. CONCLUSIONS: PEDF has protective effect on increasing AS plaque stability through ameliorating macrophage inflammation. PPAR-γ and downstream MAPKs were involved in the mechanism.

Chinese Herbal Cardiotonic Pill Stabilizes Vulnerable Plaques in Rabbits by Decreasing the Expression of Adhesion Molecules.

The cardiotonic pill (CP), consisting of a mixture of Radix Salviae Miltiorrhizae, Radix Notoginseng, and Borneolum Syntheticum, has been widely used in the prevention and treatment of cardiovascular disease. Adhesion molecules, including intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1, are involved in the development of vulnerable plaque. We investigated the effect of the CP in a rabbit model of vulnerable plaque established by local transfection with p53 gene. Compared with the control group, rabbits with vulnerable plaque showed a significantly lower intima-media thickness and plaque burden after CP treatment for 12 weeks. Moreover, the reduction in rate of plaque rupture and vulnerability index was similar. On enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and immunohistochemistry analysis, the expression of intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1 was inhibited with CP treatment. CP treatment could postpone atherosclerotic plaque development and stabilize vulnerable plaque by inhibiting the expression of adhesion molecules in treatment of cardiovascular disease.

Photoinduced electron transfer between 2-methylanthraquinone and triethylamine in an ionic liquid: time-resolved EPR and transient absorption spectroscopy study.

Photoinduced electron transfer between 2-methylanthraquinone (MeAQ) and triethylamine (TEA) in a room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), was investigated by comparing the time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and the transient absorption spectroscopy. The results of TR-EPR spectroscopy, in which MeAQ was 8 mmol L(-1) and TEA was 150 mmol L(-1), indicated that the transient radical would exist longer time in [bmim][PF6] than in acetonitrile. At the delay time of 8 µs after laser excitation, the TR-EPR signal transformed from an emissive peak into an absorptive peak when the experiment was performed in [bmim][PF6]. The results of the transient absorption spectroscopy, in which MeAQ was 0.1 mmol L(-1) and TEA was 2.2 mmol L(-1), showed that the efficiency and the rate of the photoinduced electron transfer reaction in [bmim][PF6] were obviously lower than that in acetonitrile. It was concluded that various factors, such as concentration, viscosity and local structural transformation of the solution, have an influence on the process of photoinduced electron transfer in [bmim][PF6].

Laparoscopic sleeve gastrectomy versus laparoscopic Roux-en-Y gastric bypass for morbid obesity and related comorbidities: a meta-analysis of 21 studies.

Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are two most common weight loss procedures; our meta-analysis aims to compare these two in the treatment of morbid obesity and its related comorbidities. An electronic literature research of published studies concerning LRYGB and LSG was performed from inception to October 2013. Percentage of excess weight loss (%EWL), resolution or improvement rate of comorbidities, and adverse events were all pooled and compared by the software Review Manager 5.1. As a result, a total of 21 studies involving 18,766 morbidly obese patients were eventually selected according to the inclusion criteria. No significant difference was found in %EWL during 0.5- to 1.5-year follow-up (P > 0.05), but after that, LRYGB achieved higher %EWL than LSG (P < 0.05). Except for type 2 diabetes mellitus (T2DM) (P < 0.001), the difference between these two procedures in the resolution or improvement rate of other comorbidities did not reach a statistical significance (P > 0.05). There were more adverse events in LRYGB compared with LSG (P < 0.01). In conclusion, LRYGB is superior to LSG in efficacy but inferior to LSG in safety.

Relationship between carotid artery intima-media thickness and cardiovascular risk factors in Chinese Uygur population.

AIMS: To investigate the relationships between carotid intima-media thickness (IMT) and conventional cardiovascular risk factors in Uygur population. METHODS: In totally 226 Uygur subjects, common carotid IMT values were detected, and the anthropometric and laboratory measurements were recorded. RESULTS: Correlation analysis showed that the factors of age, BMI, SBP, DBP, PP, hypertension, TC, LDL-C, TG, Apo B, diabetes mellitus, glucose, smoking status, creatinine, IHD, and stroke were significantly and positively associated with carotid IMT in Uygur males. In Uygur females, significant positive associations with carotid IMT were observed for age, BMI, SBP, DBP, PP, hypertension, TC, LDL-C, TG, diabetes mellitus, glucose, IHD, and stroke, and a significant inverse association was found for HDL-C. Multiple regression analyses suggested that LDL-C, age, TG, creatinine, BMI, smoking, hypertension, and diabetes were independently associated with carotid IMT in Uygur males. However, for carotid IMT in Uygur females, SBP, age, TG, HDL-C, BMI, and diabetes were independent determinants. CONCLUSION: Carotid artery IMT could be used as a predictive tool for atherosclerotic lesions and cardiovascular diseases in Uygur population, which might contribute to the prevention and management of the local disease.