Hydrodynamics-Controlled Single-Particle Electrocatalysis.

Electrocatalysis is considered promising in renewable energy conversion and storage, yet numerous efforts rely on catalyst design to advance catalytic activity. Herein, a hydrodynamic single-particle electrocatalysis methodology is developed by integrating collision electrochemistry and microfluidics to improve the activity of an electrocatalysis system. As a proof-of-concept, hydrogen evolution reaction (HER) is electrocatalyzed by individual palladium nanoparticles (Pd NPs), with the development of microchannel-based ultramicroelectrodes. The controlled laminar flow enables the precise delivery of Pd NPs to the electrode-electrolyte interface one by one. Compared to the diffusion condition, hydrodynamic collision improves the number of active sites on a given electrode by 2 orders of magnitude. Furthermore, forced convection enables the enhancement of proton mass transport, thereby increasing the electrocatalytic activity of each single Pd NP. It turns out that the improvement in mass transport increases the reaction rate of HER at individual Pd NPs, thus a phase transition without requiring a high overpotential. This study provides new avenues for enhancing electrocatalytic activity by altering operating conditions, beyond material design limitations.

Response mechanism of a highly efficient partial nitritation-anammox (PN/A) process under antibiotic stress: Extracellular polymers, microbial community, and functional genes.

The Partial nitritation-Anammox (PN/A) process can be restricted when treating high ammonia nitrogen wastewater containing antibiotics. This study aims to explore the response mechanism of the PN/A process under antibiotic stress. Results showed the PN/A process achieved a nitrogen removal rate higher than 1.01 ± 0.03 kg N/m3/d under long-term sulfamethazine stress. The increase of extracellular polymers from 22.52 to 43.96 mg/g VSS was conducive to resisting antibiotic inhibitory. The increase of Denitratisoma and SM1A02 abundance as well as functional genes nirS and nirK indicated denitrifiers should play an important role in the stability of the PN/A system under sulfamethazine stress. In addition, antibiotic-resistant genes (ARGs) sul1 and intI1 significantly increased by 8.78 and 5.12 times of the initial values to maintain the resistance of PN/A process to sulfamethazine stress. This study uncovers the response mechanism of the PN/A process under antibiotic stress, offering a scientific basis and guidance for further application in the future.

Biomechanical Analysis Reveals Shoulder Instability With Bipolar Bone Loss Is Best Treated With Dynamic Anterior Stabilization for On-Track Lesions and With Remplissage for Off-Track Lesions.

PURPOSE: To compare the biomechanical effects of augmenting Bankart repair (BR) with either remplissage or dynamic anterior stabilization (DAS) in the treatment of anterior shoulder instability with on-track or off-track bipolar bone loss. METHODS: Eight fresh-frozen cadaveric shoulders were tested at 60° of glenohumeral abduction in the intact, injury, and repair conditions. Injury conditions included 15% glenoid bone loss with an on-track or off-track Hill-Sachs lesion as previously recommended. Repair conditions included isolated BR, BR with remplissage, and BR with DAS (long head of biceps transfer). The glenohumeral stability was assessed by measuring the anterior translation under 0, 10, 20, 30, 40, 50 N load and maximum load without causing instability at mid-range (60°) and end-range (90°) external rotation (ER). Maximum range of motion (ROM) was measured by applying a 2.2-N·m torque in passive ER and internal rotation. RESULTS: Isolated BR failed to restore native glenohumeral stability in both on-track and off-track bipolar bone loss models. Both remplissage and DAS significantly decreased the anterior instability in the bipolar bone loss models, showing better restoration than the isolated BR. In the on-track lesions, DAS successfully restored native glenohumeral stability and mobility, whereas remplissage significantly decreased anterior translation without load (-2.12 ± 1.07 mm at 90° ER, P = .003; -1.98 ± 1.23 mm at 60° ER, P = .015). In the off-track lesions, remplissage restored native glenohumeral stability but led to significant ROM limitation (-8.6° ± 2.3° for internal rotation, P < .001; -13.9° ± 6.2° for ER, P = .003), whereas DAS failed to restore native stability at 90° ER regarding the increased anterior translation under 50 N (4.10 ± 1.53 mm, P < .001) and decreased maximum load (-13.8 ± 9.2 N, P = .021). CONCLUSIONS: At time-zero, both remplissage and DAS significantly reduced residual anterior instability compared with isolated BR in the bipolar bone loss models and restored the native glenohumeral stability under most translational loads. However, remplissage could decrease the anterior translation without load for on-track lesions and may restrict ROM for off-track lesions, whereas DAS failed to restore native stability under high translational loads for off-track lesions. CLINICAL RELEVANCE: DAS could be recommended to treat on-track bipolar bone loss with less biomechanical adverse effects, whereas remplissage might be the preferred procedure to address off-track bipolar bone loss for better stability.

Double-Level Knee Derotational Osteotomy Yields Better Postoperative Outcomes Than Tibial Tubercle Transfer Combined With Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Instability and Severe Malrotation.

PURPOSE: To assess the postoperative outcomes of double-level knee derotational osteotomy (KDRO) combined with medial patellofemoral ligament reconstruction (MPFLR) and to compare it with tibial tuber transfer (TTT) and MPFLR without derotational osteotomy in patients with recurrent patellar instability and a marked torsional deformity. METHODS: From March 2020 to December 2021, patients with torsion deformity (combined femoral torsion [FT] and tibial torsion [TTn] ≥30°) were retrospectively included. The minimum follow-up time was 18 months. Patients who received KDRO and MPFLR were categorized as the KDRO group and patients who received a combined TTT and MPFLR were categorized as the control group. Preoperative and postoperative clinical symptoms, patient-reported outcomes (Kujala, visual analog scale, Lysholm, International Knee Documentation Committee, Tegner, and Knee Injury and Osteoarthritis Outcome scores), and imaging parameters (FT, TTn, patellar height, femoral trochlear dysplasia, congruence angle, patellar tilt angle, lateral patellar angle, lateral patellar translation, and tibial tubercle-trochlear groove distance) were analyzed. RESULTS: In all, 36 patients were included with 18 in KDRO group and 18 in control group. The mean follow-up time was 30 (range 21-39) months. At the latest follow-up, no patient experienced redislocation in either group. Except for the FT and TTn in the control group, postoperative imaging parameters were significantly reduced to the normal range. KDRO group had a lower patellar tilt angle (P = .043, effect size 0.64). All clinical scores in both groups significantly improved postoperatively. The KDRO group had better functional scores than control group except the KOOS daily living activities subscore and the KOOS sports and recreation subscore. More patients in the KDRO group met the minimal clinically important difference for most patient-reported outcomes than the control group. Eight patients (44%) in the control group complained of postoperative anterior knee pain, compared with 1 patient (6%) in the KDRO group (P = .018). CONCLUSIONS: KDRO combined with MPFLR was associated with better postoperative outcomes than TTT combined with MPFLR in patients with recurrent patellar instability and a torsion deformity. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Unlocking Single Particle Anisotropy in Real-Time for Photoelectrochemistry Processes at the Nanoscale.

The key to rationally and rapidly designing high-performance materials is the monitoring and comprehension of dynamic processes within individual particles in real-time, particularly to gain insight into the anisotropy of nanoparticles. The intrinsic property of nanoparticles typically varies from one crystal facet to the next under realistic working conditions. Here, we introduce the operando collision electrochemistry to resolve the single silver nanoprisms (Ag NPs) anisotropy in photoelectrochemistry. We directly identify the effect of anisotropy on the plasmonic-assisted electrochemistry at the single NP/electrolyte interface. The statistical collision frequency shows that heterogeneous diffusion coefficients among crystal facets facilitate Ag NPs to undergo direction-dependent mass transfer toward the gold ultramicroelectrode. Subsequently, the current amplitudes of transient events indicate that the anisotropy enables variations in dynamic interfacial electron transfer behaviors during photothermal processes. The results presented here demonstrate that the measurement precision of collision electrochemistry can be extended to the sub-nanoparticle level, highlighting the potential for high-throughput material screening with comprehensive kinetics information at the nanoscale.

Multiphase Chemistry under Nanoconfinement: An Electrochemical Perspective.

Most relevant systems of interest to modern chemists rarely consist of a single phase. Real-world problems that require a rigorous understanding of chemical reactivity in multiple phases include the development of wearable and implantable biosensors, efficient fuel cells, single cell metabolic characterization techniques, and solar energy conversion devices. Within all of these systems, confinement effects at the nanoscale influence the chemical reaction coordinate. Thus, a fundamental understanding of the nanoconfinement effects of chemistry in multiphase environments is paramount. Electrochemistry is inherently a multiphase measurement tool reporting on a charged species traversing a phase boundary. Over the past 50 years, electrochemistry has witnessed astounding growth. Subpicoampere current measurements are routine, as is the study of single molecules and nanoparticles. This Perspective focuses on three nanoelectrochemical techniques to study multiphase chemistry under nanoconfinement: stochastic collision electrochemistry, single nanodroplet electrochemistry, and nanopore electrochemistry.

Free nitrous acid prediction in ANAMMOX process using hybrid deep neural network model.

Free nitrous acid (FNA) is a critical metric for stabilization of ANAMMOX but can not be directly and immediately measured by sensors or chemical measurement method, which hinders the effective management and operation for ANAMMOX. This study focuses on FNA prediction using hybrid model based on temporal convolutional network (TCN) combined with attention mechanism (AM) optimized by multiobjective tree-structured parzen estimator (MOTPE), called MOTPE-TCNA. A case study in an ANAMMOX reactor is carried out. Results show that nitrogen removal rate (NRR) is highly correlated with FNA concentration, indicating that it can forecast the operational status by predicting FNA. Then, MOTPE successfully optimizes the hyperparameters of TCN, helping TCN achieve a high prediction accuracy, and AM furtherly improves model accuracy. MOTPE-TCNA obtains the highest prediction accuracy, whose R2 value gets 0.992, increasing 1.71-11.80% compared to other models. As a deep neural network model, MOTPE-TCNA has more advantages than traditional machine learning methods in FNA prediction, which is beneficial to maintain the stable operation and easy control for ANAMMOX process.

Monitoring Photoinduced Interparticle Chemical Communication In Situ.

Monitoring interparticle chemical communication plays a critical role in the nanomaterial synthesis as this communication controls the final structure and stability of global nanoparticles (NPs). Yet most ensemble analytical techniques, which could only reveal average macroscopic information, are unable to elucidate NP-to-NP interactions. Herein, we employ stochastic collision electrochemistry to track the morphology transformation of Ag NPs in photochemical process at the single NP level. By further statistical analysis of time-resolved current transients, we quantitatively determine the dynamic chemical potential difference and interparticle communication between populations of large and small Ag NPs. The high sensitivity of stochastic collision electrochemistry enables the in situ investigation of chemical communication-dependent transformation kinetics of NPs in photochemical process, shedding light on designing nanomaterials.

Treponema pallidum Tp0751 alters the expression of tight junction proteins by promoting bEnd3 cell apoptosis and IL-6 secretion.

BACKGROUND: Neurosyphilis is a serious complication caused by the invasion of the central nervous system by Treponema pallidum subsp. pallidum (T. pallidum). However, the molecular mechanism by which T. pallidum crosses the blood-brain barrier has not been fully elucidated. OBJECTIVES: The primary purpose of this experimental design was to explore the effect of the T. pallidum adhesion protein Tp0751 on the blood-brain barrier and cerebrovascular endothelial cells. METHODS: BEnd3 cells were used to construct a monolayer blood-brain barrier model in vitro. The integrity of blood-brain barrier model was evaluated by a transendothelial cell resistance meter and transmission electron microscope after the stimulation of recombinant protein TP0751. Hoechst 33258 staining and flow cytometry were used to detect the apoptosis rate. Western blotting assay was used to measure the expression of tight junction proteins and apoptosis-related proteins. The enzyme activity detection kit was responsible for detecting the enzyme activities of Caspase 3, Caspase 8 and Caspase 9. The expression of pro-inflammatory cytokines TNF-α, IL-1ß and IL-6 at the transcription and translation levels were detected by qRT-PCR and ELISA, respectively. RESULTS: The results showed that, the tight junction structures between cells showed no obvious fragmentation, but the levels of the tight junction proteins zonula occludens-1 and occludin were reduced by the effects of Tp0751 on bEnd3 cells. In addition, further research demonstrated that after incubation with bEnd3 cells, Tp0751 induced cell apoptosis in a concentration- and time-dependent manner via the caspase 8/caspase 3 pathway. These apoptotic processes may have contributed to the changes in tight junction proteins expression. Furthermore, the Tp0751 protein may be involved in the pathogenic process by which T. pallidum crosses the blood-brain barrier by promoting secretion of the proinflammatory factor interleukin-6. CONCLUSIONS: On the whole, this study is the first to reveal and highlight that Tp0751 may affect the expression of tight junction proteins by inducing apoptosis and promoting the secretion of the inflammatory cytokine IL-6, thus playing a role in the progression of neurosyphilis caused by T. pallidum.

Understanding the Dynamic Potential Distribution at the Electrode Interface by Stochastic Collision Electrochemistry.

The potential distribution at the electrode interface is a core factor in electrochemistry, and it is usually treated by the classic Gouy-Chapman-Stern (G-C-S) model. Yet the G-C-S model is not applicable to nanosized particles collision electrochemistry as it describes steady-state electrode potential distribution. Additionally, the effect of single nanoparticles (NPs) on potential should not be neglected because the size of a NP is comparable to that of an electrode. Herein, a theoretical model termed as Metal-Solution-Metal Nanoparticle (M-S-MNP) is proposed to reveal the dynamic electrode potential distribution at the single-nanoparticle level. An explicit equation is provided to describe the size/distance-dependent potential distribution in single NPs stochastic collision electrochemistry, showing the potential distribution is influenced by the NPs. Agreement between experiments and simulations indicates the potential roles of the M-S-MNP model in understanding the charge transfer process at the nanoscale.

Tracking the Electrocatalytic Activity of a Single Palladium Nanoparticle for the Hydrogen Evolution Reaction.

The nanoparticle-based electrocatalysts' performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre-sized electrode for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2-5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs' electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency.

A soluble endoplasmic reticulum factor as regenerative therapy for Wolfram syndrome.

Endoplasmic reticulum (ER) stress-mediated cell death is an emerging target for human chronic disorders, including neurodegeneration and diabetes. However, there is currently no treatment for preventing ER stress-mediated cell death. Here, we show that mesencephalic astrocyte-derived neurotrophic factor (MANF), a neurotrophic factor secreted from ER stressed cells, prevents ER stress-mediated ß cell death and enhances ß cell proliferation in cell and mouse models of Wolfram syndrome, a prototype of ER disorders. Our results indicate that molecular pathways regulated by MANF are promising therapeutic targets for regenerative therapy of ER stress-related disorders, including diabetes, retinal degeneration, neurodegeneration, and Wolfram syndrome.

Monitoring Hydrogen Evolution Reaction Catalyzed by MoS2 Quantum Dots on a Single Nanoparticle Electrode.

Hydrogen evolution reaction (HER) catalyzed by molybdenum sulfide quantum dots (MoS2 QDs) has attracted extensive attention in the energy field. Monitoring HER catalyzed by MoS2 QDs based on a glass nanopore with an electrochemically confined effect was proposed for the first time. MoS2 QDs inside the glass nanopore is driven toward the orifice of the nanopore and bonded with the Ag nanoparticles (Ag NPs) to form a single nanocomposite. When enough voltage is applied across the orifice, the single Ag NP acts as a single nanoparticle electrode to conduct the electrochemically bipolar reaction on its two extremities. In the process, HER is catalyzed by MoS2 QDs, and Ag NPs are oxidized at the same time. The appearance of blockages on the elevated ionic current is attributed to the generation of a H2 bubble. Furthermore, by analyzing the modulations in the ionic current oscillation, the frequency of hydrogen bubble generation that is related to the catalytic efficiency of MoS2 QDs could be estimated. The results reveal the capability of the glass nanopore for the real-time monitoring electrocatalytic behavior, which makes the glass nanopore an ideal candidate to further reveal the heterogeneity of catalytic capability at the single particle level.

Self-Assembly of Au Nanoparticles and Quantum Dots by Functional Sol-Gel Silica Layers.

A layer-by-layer (LbL) self-assembled method has been developed to create the nano architectonics consisted of quantum dots (QDs) including hydrophobic CdSe/CdZnS and hydrophilic CdTe and Au nanoparticles (NPs) through a functional silica layer as a linker on a slide glass. The glass layer was created by the hydrolysis of 3-aminopropyltrimethoxysilane (APS), in which the amino group in APS plays an important role for the connection among QDs and Au NPs. UV-vis and PL spectroscopy, scanning electron microscopy, and transmission electron microscopy were employed to characterize. The result reveals that Au NPs or QDs could be dispersed in the glass slides at a high concentration, and little aggregation. The PL intensity and absorbance is linearly increased with the number of dipping cycles. Furthermore, when the glass layer between Au NPs and CdTe QDs is thin, the PL of the QDs quenched because of the Plasmon-enhanced fluorescence resonance energy transfer. In contrast, the bright PL of the QDs was observed when the glass layer became thick. The LbL self-assembled glass film shows excellent stability and transparency, which can make a promise for application in biochemical, optoelectronic, and clinical diagnosis areas.

Effect of pH on Au Nanorods in Ag Ion-Assisted Seed-Mediated Growth.

Au nanorods (NRs) with different aspect ratios were synthesized using a silver ion-assisted seed-mediated growth method through controlling the pH of solutions using hydrochloric acid to adjust the pH values of solutions. The Au NRs with longitudinal absorption peak range from 713 nm to 916 nm were fabricated by adjusting the concentrations of silver nitrate, hydrochloric acid, and cetyltrimethy-lammonium bromide in the growth solution. It was found that silver ions and hydrochloricacid were used together to systematically tune the shape and size of Au NRs. H+ ions other than Cl- ions play important role to govern the growth of Au NRs. Au NRs with a large aspect ratio and high yield can be synthesized in a relative high silver nitrate concentration and a low pH value. In optimal conditions, the Au NRs reveal an average diameter of 10 nm and length of 60 nm. Namely, the Au NRs became slender at a lower pH value and higher concentration of the AgNO3 in the growth solution.

Assembled Behavior of Noble Metal Nanoparticles Related to Capping Agents in Sol­Gel Process.

The assembly of noble metal nanoparticles (NPs) created using different capping agents was investigated in a sol­gel process. By controlling the hydrolysis and condensation of tetraethyl orthosilicate (TEOS), noble metal NPs were assembled and fixed permanently through the anisotropic growth of SiO2 shell. Various morphological noble metal NP assemblies including single bead, dimer, and pearl-chain were fabricated by controlling the addition of TEOS. Noble metal NPs were homogenously coated with SiO2 shell without using a bulk polymer or silane coupling agent as the surface primer. It is worth noting that the assembled noble metal NPs which stabilized by different stabilizers performed different UV-vis adsorption spectra. With increasing the length of assemblies, longitudinal Plasmon resonance band appears and can be tuned from visible to near-infrared. These assemblies could be applies in biomedicine area, particularly as biosensors, Raman-tag particles, and photothermal therapy.

A calcium-dependent protease as a potential therapeutic target for Wolfram syndrome.

Wolfram syndrome is a genetic disorder characterized by diabetes and neurodegeneration and considered as an endoplasmic reticulum (ER) disease. Despite the underlying importance of ER dysfunction in Wolfram syndrome and the identification of two causative genes, Wolfram syndrome 1 (WFS1) and Wolfram syndrome 2 (WFS2), a molecular mechanism linking the ER to death of neurons and ß cells has not been elucidated. Here we implicate calpain 2 in the mechanism of cell death in Wolfram syndrome. Calpain 2 is negatively regulated by WFS2, and elevated activation of calpain 2 by WFS2-knockdown correlates with cell death. Calpain activation is also induced by high cytosolic calcium mediated by the loss of function of WFS1. Calpain hyperactivation is observed in the WFS1 knockout mouse as well as in neural progenitor cells derived from induced pluripotent stem (iPS) cells of Wolfram syndrome patients. A small-scale small-molecule screen targeting ER calcium homeostasis reveals that dantrolene can prevent cell death in neural progenitor cells derived from Wolfram syndrome iPS cells. Our results demonstrate that calpain and the pathway leading its activation provides potential therapeutic targets for Wolfram syndrome and other ER diseases.