Effects of supplementary Da Dingfeng Zhu therapy on patients with Parkinson's disease of liver-kidney yin deficiency pattern.

BACKGROUND: This study aimed to verify whether the combined use of Da Dingfengzhu and Western medicine in treating Parkinson's disease (PD) can lead to therapeutic efficacy and symptom alleviation, thereby achieving a complementary and synergistic effect. METHODS: In this study, 158 patients were initially enrolled, with 116 eligible patients randomly divided into a control and an observation group. The control group received levodopa/benserazide and pramipexole, while the observation group received Da Dingfengzhu combined with levodopa/benserazide and pramipexole for 12 weeks. Baseline patient characteristics, adverse reactions, and blood samples were collected at baseline and 12 weeks post-treatment. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess symptom severity at baseline, four weeks into treatment, and 12 weeks post-treatment. RESULTS: Adverse reactions during treatment were similar in both groups, suggesting that the combined therapy in the observation group did not increase adverse effects. Both groups showed improvements in UPDRS scores, with the observation group displaying more significant symptom alleviation at 4 and 12 weeks. Moreover, the observation group exhibited more pronounced increases in serum neurotrophic factor-3 and dopamine levels and greater reductions in oxidative stress and inflammatory response markers. CONCLUSION: In conclusion, the combination of Da Dingfengzhu with levodopa/benserazide and pramipexole for treating PD shows significant clinical potential and is worthy of broader application.

Dysfunction of Chloroplast Protease Activity Mitigates pgr5 Phenotype in the Green Algae Chlamydomonas reinhardtii.

Researchers have described protection mechanisms against the photoinhibition of photosystems under strong-light stress. Cyclic Electron Flow (CEF) mitigates electron acceptor-side limitation, and thus contributes to Photosystem I (PSI) protection. Chloroplast protease removes damaged protein to assist with protein turn over, which contributes to the quality control of Photosystem II (PSII). The PGR5 protein is involved in PGR5-dependent CEF. The FTSH protein is a chloroplast protease which effectively degrades the damaged PSII reaction center subunit, D1 protein. To investigate how the PSI photoinhibition phenotype in pgr5 would be affected by adding the ftsh mutation, we generated double-mutant pgr5ftsh via crossing, and its phenotype was characterized in the green algae Chlamydomonas reinhardtii. The cells underwent high-light incubation as well as low-light incubation after high-light incubation. The time course of Fv/Fm values in pgr5ftsh showed the same phenotype with ftsh1-1. The amplitude of light-induced P700 photo-oxidation absorbance change was measured. The amplitude was maintained at a low value in the control and pgr5ftsh during high-light incubation, but was continuously decreased in pgr5. During the low-light incubation after high-light incubation, amplitude was more rapidly recovered in pgr5ftsh than pgr5. We concluded that the PSI photoinhibition by the pgr5 mutation is mitigated by an additional ftsh1-1 mutation, in which plastoquinone pool would be less reduced due to damaged PSII accumulation.

Reconfiguration, Welding, Reprogramming, and Complex Shape Transformation of An Optical Shape Memory Polymer Network Enabled by Patterned Secondary Crosslinking.

Stimuli-triggered generation of complicated 3D shapes from 2D strips or plates without using sophisticated molds is desirable and achieving such 2D-to-3D shape transformation in combination with shape reconfiguration, welding, and reprogramming on a single material is very challenging. Here, a convenient and facile strategy using the solution of a disulfide-containing diamine for patterned secondary crosslinking of an optical shape-memory polymer network is developed to integrate the above performances. The dangling thiolectones attached to the backbones react with the diamine in the solution-deposited region so that the secondary crosslinking may not only weld individual strips into assembled 3D shapes but also suppress the relaxation of the deformed polymer chains to different extents for shape reconfiguration or heating-induced complex 3D deformations. In addition, as the dynamic disulfide bonds can be thermally activated to erase the initial programming information and the excessive thiolectones are available for subsequent patterned crosslinking, the material also allows shape reprogramming. Combining welding with patterning treatment, it is further demonstrated that a gripper can be assembled and photothermally controlled to readily grasp an object.

A three-channel thermal dissociation cavity ring-down spectrometer for simultaneous measurement of ambient total peroxy nitrates, total alkyl nitrates, and NO2.

A newly constructed thermal dissociation cavity ring-down spectrometer (TD-CRDS) for the simultaneous measurement of ambient total peroxy nitrates (ΣPNs, RO2NO2), total alkyl nitrates (ΣANs, RONO2), and NO2 was presented in this work. ΣPNs and ΣANs were detected as NO2 with the CRDS instrument after thermal dissociation. PNs and ANs completely dissociated at 180 °C and 360 °C, with conversion efficiencies of 96 % and 99 %, respectively. The effects of NO2 and NO on measurement in different temperatures and two types of thermal dissociation inlet (TDI) were further explored. The influence of ambient NO2 and NO on PNs and ANs in the improved TDI (TDI-2) was significantly improved. To further enhance the measurement accuracy, the consistency of the observed NO2 in the three channels was tested, which achieved good agreement. The detection limits of the TD-CRDS instrument for NO2, ΣPNs, and ΣANs were determined as 6.5, 6.8, and 8.6 pptv (10 s, 1σ), respectively. Observations of PNs and ANs were conducted in a suburban site in Hefei, China, from September 2-30, 2021, using the TD-CRDS instrument, and the consecutive time series of PNs and ANs were derived, verifying the capability of the TD-CRDS instrument for continuous field observations of ΣPNs and ΣANs.

Characterization of tryptophan oxidation affecting D1 degradation by FtsH in the photosystem II quality control of chloroplasts.

Photosynthesis is one of the most important reactions for sustaining our environment. Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. Light in excess, however, causes the simultaneous production of reactive oxygen species (ROS), leading to photo-oxidative damage in PSII. To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. In PSII subunits, photo-oxidative modifications of several amino acids such as Trp have been indeed documented, whereas the linkage between such modifications and D1 degradation remains elusive. Here, we show that an oxidative post-translational modification of Trp residue at the N-terminal tail of D1 is correlated with D1 degradation by FtsH during high-light stress. We revealed that Arabidopsis mutant lacking FtsH2 had increased levels of oxidative Trp residues in D1, among which an N-terminal Trp-14 was distinctively localized in the stromal side. Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH.

Nocturnal Bladder Function and Sleep in the Children with Refractory Nocturnal Enuresis: A Prospective Study.

OBJECTIVE: To prospectively investigate the nocturnal bladder function and sleep in children with refractory primary monosymptomatic nocturnal enuresis (RPMNE). MATERIALS AND METHODS: Fifty-three children diagnosed with RPMNE and 30 controls who had upper urinary tract abnormality but without any voiding problems were included in the study. RPMNE patients underwent a standardized investigation protocol, including the Pittsburgh Sleep Quality Index (PSQI) questionnaire, a 7-day bladder diary, and the simultaneous ambulatory urodynamic monitoring and polysomnography (PSG); controls were evaluated using the PSQI questionnaire and PSG. RESULTS: The children with RPMNE were subdivided into the nocturnal detrusor overactivity (NDO) case group and the non-NDO case group. The children in the NDO case group had a higher percentage of total sleep time in light sleep and a lower percentage in the N3 sleep stage than those in the non-NDO case group and control group (P <.05). The cortical arousal index and PSQI scores of both RPMNE subgroups were higher compared to the control group (P <.05). The incidences of reduced nocturnal bladder capacity (NBC) in the NDO case group were higher than in the non-NDO case group (P <.05). The frequency of involuntary detrusor contractions during sleep was positively correlated with cortical arousal index in the NDO case group (r = 0.811, P <.0001). CONCLUSION: In addition to the reduced NBC, the RPMNE is related to abnormal NDO, increased light sleep period, and cortical arousal dysfunction. Moreover, there is a certain correlation between the abnormal degrees of NDO and cortical arousal dysfunction.

Revealing the composite fretting-corrosion mechanisms of Ti6Al4V alloy against zirconia-toughened alumina ceramic in simulated body fluid.

The composite fretting-corrosion damage due to combinations of radial, tangential, rotational, and other fretting causes local adverse tissue reactions and failure of artificial joints. Previous studies have mainly focused on the single fretting mode, while ignoring the coupled effects of multimode fretting. The fretting-corrosion mechanisms between the components are not yet fully understood. In this study, the tangential-radial composite fretting was realized by applying a normal alternating load to the tangential fretting. The composite fretting corrosion behavior of zirconia toughened alumina ceramic/Ti6Al4V alloy used for the head-neck interface of an artificial hip joint under simulated body fluid was investigated. The effects of displacement and alternating load amplitude were considered. The alternating load amplitude was given by the maximum normal load and minimum normal load ratio R. The results showed that the composite fretting damage mechanisms of this pair were mainly abrasion and tribocorrosion. Cracking also existed under large displacement. The effect of alternating load on fretting corrosion was found to be mainly caused by changes in the contact area and instantaneous contact state. In addition, the alternating load during the composite fretting promoted the formation of the three-body layer in the contact area. A decrease in load ratio caused fretting to change from gross to partial slip. In the case of small displacement, the load ratio had little effect on the friction work or wear scar profile. The corrosion rate of materials and the concentration of metal ions released into the solution increased as load ratio decreased. In cases of large and medium displacement, load ratio reduction increased the friction work and expanded the wear scar. The reduction in load ratio also caused the corrosion rate of the material to increase and then decrease, and the metal ion concentration decreased.

Sequentially Controlled Recognition of Different Proteins Using Programmable Protein Imprinted Nanospheres.

Although protein imprinted materials with multiple templates are developed to selectively separate different proteins, it is difficult to achieve the programmed adsorption and separation of different proteins using one material, because the available protein imprinted materials are constructed through irreversible crosslinking and their structures are unprogrammable and non-reconstructive. Herein, a novel nanosphere (MS@PTL-g-PNIPAM) is designed, which not only is temperature and pH responsive but also can dynamically reversibly crosslink/de-crosslink under ultraviolet light of different wavelengths. With the help of the dynamically reversible photo-crosslinking, the nanospheres can be repeatedly programmed into protein imprinted nanospheres toward different target proteins. Moreover, the prepared imprinted nanospheres can easily achieve the controlled rebinding and release of target proteins, benefiting from the introduced temperature- and pH-responsive moieties. As a consequence, this study realizes the specific separation of different target proteins from protein mixture and the real bovine blood sequentially by programming one material. It is resource saving, time saving, recyclable, and it will provide convenience for protein imprinted materials to use in the blood purification, drug delivery, and virus detection.

Fretting corrosion behavior of Ti6Al4V alloy against zirconia-toughened alumina ceramic in simulated body fluid.

The fretting corrosion at the head-neck interface of artificial hip joints is an important reason for the failure of prostheses. The Ti6Al4V alloy-zirconia-toughened alumina (ZTA) ceramic combination has been widely used to make the head and neck of artificial hip joints. In this study, its fretting corrosion behavior in simulated body fluid was studied by electrochemical monitoring, surface morphology characterization, and chemical composition analysis. A running condition fretting map (RCFM) of load and displacement was established, including three regimes, namely partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). The friction dissipation energy increased gradually from the PSR to MFR and GSR. In the PSR, the damage mechanisms were slight abrasive wear and tribocorrosion at the edge of contact area, as well as extremely slight adhesive wear at the center. In the MFR, the damage mechanisms were mainly adhesive wear, abrasive wear, and corrosive wear. In the GSR, the damage mechanism was serious abrasive wear, fatigue wear, and corrosive wear combined with slight adhesive wear. Finally, an ion-concentration map was created, displaying the material-loss transition of different displacements and loads. The material loss increased with the increased displacement, and increased first and then decreased with the increased load.

Functional thiolactone assisted imprinting cavities with abundant amines for strong binding of protein imprinted nanospheres.

In order to develop new protein imprinting polymerization methods and to prepare protein imprinted nanomaterials with high recognition, a novel protein imprinted strategy is developed in this study by using polyethyleneimine (PEI) for aminolysis of tailor-made thiolactone-based functional monomers and crosslinkers on amine-modified magnetic nanospheres in an aqueous medium. The prepared protein imprinted nanospheres can seize BSA templates in the imprinting polymerization process through multiple hydrogen bonds, and hydrophobic and electrostatic interactions. In addition, the aminolysis reaction also generates abundant amide bonds in the imprinting polymer network, which not only enhances the hydrogen bonding interactions between the imprinted nanospheres and BSA but also improves the stability of the imprinting cavities by increasing the rigidity of the polymer chains. Based on the above advantages, the protein imprinted nanospheres show excellent rebinding specificity for BSA, for which the rebinding capacity is up to 505 ± 15 mg g-1 and the imprinting factor is 4.09. The protein imprinted nanospheres exhibit fast adsorption kinetics, outstanding reusability, and can selectively separate BSA from a protein mixture and actual biological samples. The generality of this imprinted method is also verified. Thus, this study will provide a new idea for the design of protein imprinted materials with high recognition.

Double Modification of Poly(urethane-urea): Toward Healable, Tear-Resistant, and Mechanically Robust Elastomers for Strain Sensors.

Polyurethane elastomers with mechanical robustness, tear resistance, and healing efficiency hold great potential in wearable sensors and soft robots. However, achieving excellent mechanical properties and healable capability simultaneously remains highly desirable but exclusive. Herein, we propose a straightforward procedure for double modification of poly(urethane-urea) (PUU) via thiolactone chemistry, and two different dynamic cross-linking bonds (disulfide linkages and Zn2+/imidazole coordination) are successively incorporated into the side chain of PUU, producing double cross-linking elastomers (PUU-I/Zn-S). The synergy between disulfide linkages and Zn2+/imidazole coordination forms a robust and dynamic network, endowing PUU-I/Zn-S with excellent mechanical and healing properties. The tensile stress, elongation at break, and toughness of the resultant elastomer can reach 44.06 MPa, 1000%, and 181.93 MJ m-3, respectively. Meanwhile, PUU-I/Zn-S exhibits outstanding tearing resistance with a tearing energy of 42.1 kJ m-2. The PUU-I/Zn-S can restore its mechanical robustness after self-healing at room temperature (25 ± 2 °C) or 60 °C and even maintain 91% of its original tensile strength after reprocessing two times. Additionally, PUU-I/Zn-S-based strain sensors are fabricated by introducing conductive nanofillers and demonstrate remarkable sensing capability to diverse human body motions. This work demonstrates a simple and feasible method for the postfunctionalization and enhancement of polyurethane and provides some insights into reconciling the traditional contradictory properties of mechanical robustness and healing efficiency.

Decomposition of micromotion at the head-neck interface in total hip arthroplasty during walking.

Fretting corrosion as one of the leading causes for failure of modular hip prostheses has been associated with micromotion at head-neck taper junction. Decomposition of micromotion is helpful to promote the development of more realistic experiments investigating failure mechanisms of the head-neck junction in total hip arthroplasty. The aim of this study was to decompose the complex three-dimensional micromotion at the head-neck junction into multiple fundamental modes, including three translational and three rotational components. A three-dimensional finite element model composed of head-neck junction, liner and acetabular cup with a typical 12/14 taper size, as well as the taper mismatch of -4', was developed during walking. The analysis was divided into three procedures: a) the assembly simulation of the head and neck during surgery, b) verification with a simplified axisymmetric model, and c) three-dimensional modelling under normal walking. This study revealed that the main forms of micromotion contained circumferential, longitudinal micromotion and longitudinal rolling toggling, and were closely related to the state of motion. The maximum translational micromotion was predicted to be 10.9 µm during the walking gait, with the predominant modes of the circumferential translation of 9.6 µm, the longitudinal translation of 5.5 µm and the longitudinal rotation of 0.29° along the taper junction. These findings may provide design considerations for further experimental testing about fretting and facilitate the understanding of the fretting mechanisms in hip prostheses.

Exosomes from human urine-derived stem cells carry NRF1 to alleviate bladder fibrosis via regulating miR-301b-3p/TGFßR1 pathway.

Bladder outlet obstruction (BOO) is a common disease that always make the bladder develops from inflammation to fibrosis. This study was to investigate the effect of exosomes from human urine-derived stem cells (hUSCs) on bladder fibrosis after BOO and the underlying mechanism. The BOO mouse model was established by inserting a transurethral catheter, ligation of periurethral wire, and removal of the catheter. Mouse primary bladder smooth muscle cells (BSMCs) were isolated and treated with TGFß1 to mimic the bladder fibrosis model in vitro. Exosomes from hUSCs (hUSC-Exos) were injected into the bladder of BOO mice and added into the culture of TGFß1-induced BSMCs. The associated factors in mouse bladder tissues and BSMCs were detected. It was confirmed that the treatment of hUSC-Exos alleviated mouse bladder fibrosis and down-regulated fibrotic markers (a-SMA and collagen III) in bladder tissues and TGFß1-induced BSMCs. Overexpression of NRF1 in hUSC-Exos further improved the effects of hUSC-Exos on bladder fibrosis both in vivo and in vitro. TGFßR1 was a target of NRF1 and miR-301b-3p, and miR-301b-3p was a target of NRF1. It was next characterized that hUSC-Exos carried NRF1 to up-regulate miR-301B-3p, thereby reducing TGFßR1level. Our results illustrated that hUSC-Exos carried NRF1 to alleviate bladder fibrosis through regulating miR-301b-3p/TGFßR1 pathway.

Efficacy and Safety of Sacral Neuromodulation by Converting Constant Frequency Stimulation Into Variable Frequency Stimulation in Patients With Detrusor Overactivity and Impaired Contractility: A Single-Center Prospective Study.

OBJECTIVES: In patients with detrusor overactivity with impaired contractility (DOIC), it is difficult to relieve abnormal lower urinary tract symptoms during both storage and voiding using sacral neuromodulation (SNM) with constant frequency stimulation (CFS). We sought to evaluate the efficacy and safety of SNM using variable frequency stimulation (VFS) in patients with DOIC by comparing it with outcomes of SNM with CFS. MATERIALS AND METHODS: Between September 2020 and May 2021, we prospectively enrolled 20 patients with DOIC, confirmed on urodynamic examination, and administered SNM with VFS. The patients were followed up and required to maintain voiding diaries and record scale scores of overactive bladder symptoms, psychology and quality of life, uroflowmetry, ultrasonic postvoid residual urine, and adverse events at baseline and during the CFS and VFS phases. RESULTS: The average testing phase was 26.3 ± 4.1 days. Compared with baseline values, overactive bladder symptom, psychologic health questionnaire, and quality of life scores, in addition to voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic postvoid residual (PVR) decreased significantly during both the CFS and VFS phases (p < 0.05). The average voided volume, functional bladder capacity, and maximum urine flow rate significantly increased during the CFS and VFS phases (p < 0.05). In the VFS phase, voiding frequency, urgency incontinence frequency, daily catheterization volume of voiding diary, and ultrasonic PVR further decreased (p < 0.05), whereas functional bladder capacity, maximum urine flow rate, quality of life score, overactive bladder symptom score, and psychologic health questionnaire score further improved compared with results obtained in the CFS phase (p < 0.05). In the VFS phase, the success rate of further improvement of symptoms was 85.0%, and no new complications were noted. CONCLUSIONS: SNM that converts CFS into VFS may be an effective treatment option for patients with DOIC, exhibiting no increase in adverse events.

Ring -opening of polythiolactones to construct protein-imprinted nanospheres with high recognition and regulation capabilities.

Developing and preparing novel protein-imprinted nanomaterials with high recognition ability remains challenging because it is difficult to controllably and orderly design and arrange functional groups on the imprinted polymer layers of protein-imprinted nanomaterials to improve their protein identification. Herein, we present a new technology using rationally designed polythiolactone-decorated magnetic nanospheres as the precursor of multifunctionalized imprinted materials. Moreover, the strategy of ring-opening the polythiolactione layers using primary amines with terminal alcohols, acids and pyrrolidines introduces abundant recognition sites, which enhance the recognition for template proteins through multiple hydrogen-bonding and hydrophobic interactions. Thiols generated in situ by the ring-opening reaction provide sufficient crosslinking sites proximate to each recognition site for the formation of imprinting cavities, endowing the imprinted nanospheres with promising regulation capabilities. Based on the rational design, the imprinted nanospheres can be prepared conveniently and present tunable rebinding capacity and specificity for bovine serum albumin (BSA). The maximum saturated rebinding capacity of imprinted materials for BSA is up to 285 ± 15 mg g-1 and the highest imprinting factor reaches 5.79. The simple and versatile strategy demonstrated in this study shows promise for the design of other protein-imprinted materials with high recognition ability.

Video-urodynamics efficacy of sacral neuromodulation for neurogenic bladder guided by three-dimensional imaging CT and C-arm fluoroscopy: a single-center prospective study.

To assess the efficacy of sacral neuromodulation (SNM) for neurogenic bladder (NB), guided by intraoperative three-dimensional imaging of sacral computed tomography (CT) and mobile C-arm fluoroscopy through video-urodynamics examination. We enrolled 52 patients with NB who underwent conservative treatment with poor results between September 2019 and June 2021 and prospectively underwent SNM guided by intraoperative three-dimensional imaging of sacral CT and mobile C-arm fluoroscopy. Video-urodynamics examination, voiding diary, quality of life questionnaire, overactive bladder symptom scale (OABSS) scoring, and bowel dysfunction exam were completed and recorded at baseline, at SNM testing, and at 6-month follow-up phases. Finally, we calculated the conversion rate from period I to period II, as well as the treatment efficiency and the occurrence of adverse events during the testing and follow-up phases. The testing phase of 52 NB patients was 18-60 days, with an average of (29.3 ± 8.0) days. Overall, 38 patients underwent SNM permanent electrode implantation, whose follow-up phase was 3-25 months, with an average of (11.9 ± 6.1) months. Compared with baseline, the voiding times, daily catheterization volume, quality of life score, OABSS score, bowel dysfunction score, maximum detrusor pressure before voiding, and residual urine volume decreased significantly in the testing phase. The daily voiding volume, functional bladder capacity, maximum urine flow rate, bladder compliance, and maximum cystometric capacity increased significantly in the testing phase. Besides, the voiding times, daily catheterization volume, quality of life score, OABSS score, bowel dysfunction score, maximum detrusor pressure before voiding, and residual urine volume decreased further from the testing to follow-up phase. Daily voiding volume, functional bladder capacity, maximum urine flow rate, bladder compliance, and maximum cystometric capacity increased further from testing to follow-up. At baseline, 10 ureteral units had vesicoureteral reflux (VUR), and 9 of them improved in the testing phase. Besides, there was 1 unit that further improved to no reflux during the follow-up phase. At baseline, 10 patients had detrusor overactivity (DO), and 8 of them improved in the testing phase. Besides, 1 patient's symptoms further improved during the follow-up phase. At baseline, there were 35 patients with detrusor-bladder neck dyssynergia (DBND); 14 (40.0%) of them disappeared during the testing phase. Among 13 cases who had DBND in the testing phase, 6 (46.2%) disappeared during the follow-up phase. Of the 47 patients with detrusor-external sphincter dyssynergia (DESD) at baseline, 8 (17.0%) disappeared during the testing phase. Among 26 cases who had DESD in the testing phase, 6 (23.1%) disappeared during the follow-up phase. The effective rate of this study was 88.5% (46/52), and the conversion rate from phase I to phase II was 73.1% (38/52). Additionally, the efficacy in a short-term follow-up was stable. SNM guided by intraoperative three-dimensional imaging of sacral CT and mobile C-arm fluoroscopy is an effective and safe treatment option for NB in short time follow-up. It would be well improved in the bladder storage function, sphincter synergetic function and emptying efficiency by video-urodynamics examination in this study.Trial registration: Chinese Clinical Trial Registry. ChiCTR2100050290. Registered August 25 2021. http://www.chictr.org.cn/index.aspx .

Intercomparison of OH radical measurement in a complex atmosphere in Chengdu, China.

Atmospheric oxidation is a driving force of complex air pollution, and accurate hydroxyl radical (OH) measurement is helpful in investigating the radical-cored photooxidation mechanism in the troposphere. A self-developed laser-induced fluorescence instrument by the Anhui Institute of Optics Fine Mechanics, Chinese Academy of Sciences (AIOFM-LIF), was able to measure OH concentration with high sensitivity and good time resolution, and a detection limit of 1.7 × 105 cm-3 (1σ, 30 s). A long-period, multi-level intercomparison of hydroxyl radical (OH) measurements between AIOFM-LIF and PKU-LIF (the Peking University laser-induced fluorescence system) was conducted in Chengdu, China. The measurement between two instruments was in excellent agreement in the 5-min time resolution. Linear regression analysis reported a linear slope of 0.96 with a 0.68 × 106 cm-3 offset, and the correlation coefficient R2 was 0.85. The overall linearity with only a slight offset indicated a negligible influence on OH measurement. No noticeable artifacts from ozonolysis were observed under the condition of high ozone and ozonolysis-related compound concentrations. In addition to the subtraction of background signal through wavelength modulation, the dynamic correction on ozone photolysis interference ensured high intercomparison quality in both relatively constant and rapidly varying periods. Based on the reliability of OHAIOFM and OHPKU, comparisons under different oxidation-related species (NOx, VOCs, O3, PM2.5) levels and typical scenarios (rich-BVOC and high-reactivity) were carried out to evaluate the performance under complex atmospheres. A slightly higher drift was observed in a certain scenario, but the general data variability due to environmental changes did not affect the measurement accuracy. The intercomparison demonstrated that both systems are able to achieve reliable OH data under typical conditions of complex atmospheric pollution in China. Additional improvements are necessary for future intercomparisons in order to enhance the confidence in OH detection accuracy.

Nocturnal atmospheric chemistry of NO3 and N2O5 over Changzhou in the Yangtze River Delta in China.

Comprehensive observations of the nocturnal atmospheric oxidation of NO3 and N2O5 were conducted at a suburban site in Changzhou in the YRD using cavity ring-down spectroscopy (CRDS) from 27 May to 24 June, 2019. High concentrations of NO3 precursors were observed, and the nocturnal production rate of NO3 was determined to be 1.7 ± 1.2 ppbv/hr. However, the nighttime NO3 and N2O5 concentrations were relatively low, with maximum values of 17.7 and 304.7 pptv, respectively, illustrating the rapid loss of NO3 and N2O5. It was found that NO3 dominated the nighttime atmospheric oxidation, accounting for 50.7%, while O3 and OH only contributed 34.1% and 15.2%, respectively. For the reactions of NO3 with volatile organic compounds (VOCs), styrene was found to account for 60.3%, highlighting its dominant role in the NO3 reactivity. In general, the contributions of the reactions between NO3 and VOCs and the N2O5 uptake to NO3 loss were found to be about 39.5% and 60.5%, respectively, indicating that N2O5 uptake also played an important role in the loss of NO3 and N2O5, especially under the high humidity conditions in China. The formation of nitrate at night mainly originated from N2O5 uptake, and the maximum production rate of NO3- reached 6.5 ppbv/hr. The average NOx consumption rate via NO3 and N2O5 chemistry was found to be 0.4 ppbv/h, accounting for 47.9% of the total NOx removal. The predominant roles of NO3 and N2O5 in nitrate formation and NOx removal in the YRD region was highlighted in this study.

Parametric analysis of the effect of impaction load on the stability of head-neck junction in total hip arthroplasty.

BACKGROUND: Tribocorrosion at head-neck interface is one of the main causes leading to the failure of hip implants in total hip arthroplasty. Impaction load has been acknowledged as one of the key factors influencing the stability of the taper junction. It is understood that the magnitude of impaction force differs from the surgeon to surgeon in primary total hip arthroplasty or revision. Clinically, it is sufficient enough to keep the male and female tapers inseparable utilizing a low impaction, which seems to contradict previous researches. The objective of this study was to investigate the effect of impaction loads on the stability of taper junction during assembly and gaits. METHODS: A finite element model with 12/14 taper and the taper mismatch of 4' was developed for investigation. The impaction force profiles were collected from surgeon as the inputs, and then the contact mechanics over one or multiple gaits was further analyzed and validated utilizing hip simulator test. FINDINGS: Impaction force ranging from 200 to 2000 N could provide the same taper connection effect after the first gait due to the secondary seating. As for impaction loads of 3000 N and above, an increased impaction force would lead to the tighter taper connection. INTERPRETATION: The effect of impaction load on the stability of head-neck junction is a piecewise function, indicating that the stability of taper junction is not affected by different impaction loads and tends to be consistent while its magnitude is below the threshold. Instead, the stability of taper junction is positively correlated with impaction force.

Generation and Release of OH Radicals from the Reaction of H2 O with O2 over Soot.

OH radicals in the air maintain the oxidizing power of the troposphere. A conventional view is that particulate matter (PM) in the atmosphere is a major sink of OH radicals, thereby lowering the oxidizing power of atmosphere in the event of high-level PM. By contrary, our joint experimental/theoretical study reveals a new mechanism for the generation of gaseous OH radicals by carbonaceous soot particles. We show that water and O2 react on carbonaceous surfaces and give rise to gaseous OH radicals under irradiation. With ample delocalized π electrons, carbonaceous surfaces enable the easy desorption of hydroxyl groups to produce gaseous OH radicals, evidenced by direct observation of the steady generation of OH radicals on a carbonaceous surface. Our results reveal a new chemical mechanism for the production of OH radicals.