Improving benzene catalytic oxidation on Ag/Co3O4 by regulating the chemical states of Co and Ag

Silver (9 wt.%) was loaded on Co3O4-nanofiber using reduction and impregnation methods, respectively. Due to the stronger electronegativity of silver, the ratios of surface Co3+/Co2+ on Ag/Co3O4 were higher than on Co3O4, which further led to more adsorbed oxygen species as a result of the charge compensation. Moreover, the introducing of silver also obviously improved the reducibility of Co3O4. Hence the Ag/Co3O4 showed better catalytic performance than Co3O4 in benzene oxidation. Compared with the Ag/Co3O4 synthesized via impregnation method, the one prepared using reduction method (named as AgCo-R) exhibited higher contents of surface Co3+ and adsorbed oxygen species, stronger reducibility, as well as more active surface lattice oxygen species. Consequently, AgCo-R showed lowest T90 value of 183°C, admirable catalytic stability, largest normalized reaction rate of 1.36 × 10-4 mol/(h·m2) (150°C), and lowest apparent activation energy (Ea) of 63.2 kJ/mol. The analyzing of in-situ DRIFTS indicated benzene molecules were successively oxidized to phenol, o-benzoquinone, small molecular intermediates, and finally to CO2 and water on the surface of AgCo-R. At last, potential reaction pathways including five detailed steps were proposed.

Design of infinite horizon LQR controller for discrete delay systems in satellite orbit control: A predictive controller and reduction method approach

In the realm of satellite orbit control, powerful controller design plays a pivotal role in minimizing fuel consumption and ensuring orbit stability. This article introduces an advanced approach to the design of a Linear Quadratic Regulator (LQR) controller with an infinite horizon, tailored for discrete delay systems. The proposed methodology integrates predictive control with a reduction method, aiming for optimality while addressing performance and system constraints. Formulating the control problem as a quadratic program, the predictive control method generates a sequence of control inputs using a reducing horizon strategy. Stability analysis, employing Lyapunov-Krasovsky functions and linear matrix inequalities, yields delay-independent conditions for exponential convergence. A numerical example showcases the controller's effectiveness in maintaining orbit and reducing fuel consumption, underlining its capacity to achieve control objectives despite uncertainties and time delays. This research contributes to robust control strategies in satellite orbit systems, enhancing control performance and operational efficiency.

Effect of different reduction methods on Pd/Al2O3 for o-xylene oxidation at low temperature

Pd/Al₂O₃ was pretreated by CO, H₂ and NaBH₄ reduction, respectively. The reduced catalysts were tested for o-xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of palladium hydride (TPDH). The characterizations indicate the pretreatments lead to distinct Pd particle sizes and amount of surface activated oxygen species, which are responsible for the catalytic performance. Compared with H₂ and NaBH₄ reduction methods, CO reduction shows a strong interaction between Pd and Al₂O₃ with smaller Pd particle size and more surface activated oxygen. It exhibited excellent catalytic performance, complete oxidation of 50 ppmV o-xylene at 85°C with a WHSV of 60,000 mL/(g∙hr).

Effect of reduction pretreatments on PdAg/Al2O3 for HCHO and CO oxidation

PdAg/Al₂O₃ were pretreated by CO and H₂ reduction pretreatments, respectively. The reduced catalysts were tested for HCHO and CO oxidation and characterized by Brunner Emmet Teller (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and oxygen temperature programmed desorption (O₂-TPD). These results indicate that the pretreatments have effect on PdAg reconstruction, PdAg particle size and active oxygen species, which are responsible for the catalytic performance. Compared with H₂ reduction method, CO reduction is more suitable for PdAg/Al₂O₃ pretreatment. PdAg/Al₂O₃-CO exhibited better catalytic performance.

The existence and stability of spikes in the one-dimensional Keller-Segel model with logistic growth

It is well known that Keller-Segel models serve as a paradigm to describe the self aggregation phenomenon, which exists in a variety of biological processes such as wound healing, tumor growth, etc. In this paper, we study the existence of monotone decreasing spiky steady state and its linear stability property in the Keller-Segel model with logistic growth over one-dimensional bounded domain subject to homogeneous Neumann boundary conditions. Under the assumption that chemo-attractive coefficient is asymptotically large, we construct the single boundary spike and next show this non-constant steady state is locally linear stable via Lyapunov-Schmidt reduction method. As a consequence, the multi-symmetric spikes are obtained by reflection and periodic extension. In particular, we present the formal analysis to illustrate our rigorous theoretical results.

A new lever reduction technique for the surgical treatment of elderly patients with lumbar degenerative Spondylolisthesis

BACKGROUND

Proper reduction method for Lumbar degenerative spondylolisthesis (LDS) is still controversial. The aim of this study was to determine the safety and effectiveness of lever reduction combined with traditional elevating-pull reduction technique for the treatment of elderly patients with LDS.

METHODS

From May 2015 to December 2017, 142 elderly patients (≥65 years) diagnosed with LDS were enrolled in this study with a mean follow-up of 25.42 ± 8.31 months. All patients were operated using lever reduction combined with traditional elevating-pull reduction technique. Patient age, sex, body mass index, bone mineral density, preoperative comorbidities, surgical duration, blood loss, and surgical complications were collected form patient charts. Clinical data as visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey (SF-36) were collected preoperatively, 1 month postoperatively, and at the final follow-up. Radiographic evaluation included slip percentage, slip angle (SA), lumbar lordosis (LL), and fusion status.

RESULTS

The clinical parameters of VAS_back, VAS_leg, ODI, and SF-36 had significantly improved at both follow-ups after surgery. A significant improvement was indicated for slippage reduction at both follow-ups, showing no significant correction loss after surgery. SA significantly increased after surgery and was well maintained at the final follow-up. LL was not affected by the surgery. At the final follow-up, complete fusion was obtained in 121 patients (85.2%) and partial fusion in 21 (14.8%). Revision surgery was performed for one patient. Screw loosening was observed in 3 (2.11%) cases. No nerve root injury or adjacent segment disease was observed.

CONCLUSIONS

This new lever reduction combined with traditional elevating-pull reduction technique for the surgical treatment of elderly patients with LDS is both safe and effective. Satisfactory correction and fusion rates were achieved with acceptable correction loss and reduction-related complications.

Efficient calculation of heterogeneous non-equilibrium statistics in coupled firing-rate models

Understanding nervous system function requires careful study of transient (non-equilibrium) neural response to rapidly changing, noisy input from the outside world. Such neural response results from dynamic interactions among multiple, heterogeneous brain regions. Realistic modeling of these large networks requires enormous computational resources, especially when high-dimensional parameter spaces are considered. By assuming quasi-steady-state activity, one can neglect the complex temporal dynamics; however, in many cases the quasi-steady-state assumption fails. Here, we develop a new reduction method for a general heterogeneous firing-rate model receiving background correlated noisy inputs that accurately handles highly non-equilibrium statistics and interactions of heterogeneous cells. Our method involves solving an efficient set of nonlinear ODEs, rather than time-consuming Monte Carlo simulations or high-dimensional PDEs, and it captures the entire set of first and second order statistics while allowing significant heterogeneity in all model parameters.

A neural network analysis of Lifeways cross-generation imputed data

OBJECTIVES

Neural networks are a powerful statistical tool that use nonlinear regression type models to obtain predictions. Their use in the Lifeways cross-generation study that examined body mass index (BMI) of children, among other measures, is explored here. Our aim is to predict the BMI of children from that of their parents and maternal and paternal grandparents. For comparison purposes, linear models will also be used for prediction. A complicating factor is the large amount of missing data. The missing data may be imputed and we examine the effects of different imputation methods on prediction. An analysis using neural networks (and also linear models) that uses all available data without imputation is also carried out, and is the gold standard by which the analyses with imputed data sets are compared.

RESULTS

Neural network models performed better than linear models and can be used as a data analytic tool to detect nonlinear and interaction effects. Using neural networks the BMI of a child can be predicted from family members to within roughly 2.84 units. Results between the imputation methods were similar in terms of mean squared error, as were results based on imputed data compared to un-imputed data.

Provisional pin fixation: An efficient alternative to manual maintenance of reduction in nailing of intertrochanteric fractures

INTRODUCTION

During nailing of intertrochanteric fractures, there is always a risk of reduction loss despite achieving an acceptable reduction status after a percutaneous procedure. Most surgeons usually attempted to maintain the reduction with a manual endeavor. However, we experienced varying amounts of intraoperative reduction loss and had to perform readjustments several times. These struggles motivated us to attempt provisional pin fixation as an alternative method. The purpose of this study was to analyze the factors affecting intraoperative reduction loss, especially in comparison between two methods.

MATERIALS AND METHODS

Sixty-eight patients with intertrochanteric fractures were included. They were divided into two groups based on the method, by retrospective analysis of the intraoperative c-arm image. In the manual maintenance group, an assistant maintained the instruments during the procedure. In the provisional pin fixation group, the reduction was temporaryily held by a 3.2mm guide pin fixation across the fracture. A displacement of more than one cortical thickness in any plane or angular deformity during any point in the procedure after acceptable reduction was judged as an intraoperative reduction loss. Multivariate logistic regression was used for statistical analysis.

RESULTS

The number of cases with intraoperative reduction loss was 18 (18 of 38, 46.1%) in the manual maintenance group and 6 (6 of 30, 20.0%) in the provisional pin fixation group. The odds ratio of intraoperative reduction loss in the manual maintenance group was 5.182 (95% confidence interval, 1.455-18.452) compared with the provisional pin fixation group as the reference.

CONCLUSIONS

As a reasonable approach for maintaining reduction, provisional pin fixation can significantly decrease intraoperative reduction loss after percutaneous reduction of intertrochanteric fractures during nailing.

A novel ultrasound assisted method in synthesis of NZVI particles

This research is about a novel ultrasound assisted method for synthesis of nano zero valent iron particles (NZVI). The materials were characterized using TEM, FESEM, XRD, BET and acoustic PSA. The effect of ultrasonic power, precursor/reductant concentration (NaBH4, FeSO4·7H2O) and delivery rate of NaBH4 on NZVI characteristics were investigated. Under high ultrasonic power the morphology of nano particles changed from spherical type to plate and needle type. Also, when high precursor/reductant and high ultrasonic power was used the particle size of NZVI decreased. The surface area of NZVI particles synthesized by ultrasonic method was increased when compared by the other method. From the XRD patterns it was found also the crystallinity of particles was poor.

Synthesis and antimicrobial effects of silver nanoparticles produced by chemical reduction method

BACKGROUND AND THE PURPOSE OF THE STUDY

The most prominent nanoparticles for medical uses are nanosilver particles which are famous for their high anti-microbial activity. Silver ion has been known as a metal ion that exhibit anti-mold, anti-microbial and anti-algal properties for a long time. In particular, it is widely used as silver nitrate aqueous solution which has disinfecting and sterilizing actions. The purpose of this study was to evaluate the antimicrobial activity as well as physical properties of the silver nanoparticles prepared by chemical reduction method.

METHODS

Silver nanoparticles (NPs) were prepared by reduction of silver nitrate in the presence of a reducing agent and also poly [N-vinylpyrolidone] (PVP) as a stabilizer. Two kinds of NPs were synthesized by ethylene glycol (EG) and glucose as reducing agent. The nanostructure and particle size of silver NPs were confirmed by scanning electron microscopy (SEM) and laser particle analyzer (LPA). The formations of the silver NPs were monitored using ultraviolet- visible spectroscopy. The anti-bacterial activity of silver NPs were assessed by determination of their minimum inhibitory concentrations (MIC) against the Gram positive (Staphylococcus aureus and Staphylococcus epidermidis) as well as Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria.

RESULTS AND CONCLUSION

The silver nanoparticles were spherical with particle size between 10 to 250 nm. Analysis of the theoretical (Mie light scattering theory) and experimental results showed that the silver NPs in colloidal solution had a diameter of approximately 50 nm. Both colloidal silver NPs showed high anti-bacterial activity against Gram positive and Gram negative bacteria. Glucose nanosilver colloids showed a shorter killing time against most of the tested bacteria which could be due to their nanostructures and uniform size distribution patterns.