Recapitulating the immune system of hemophilia A patients with inhibitors using immunodeficient mice.

BACKGROUND AND AIM: Treating hemophilia A patients who develop inhibitors remains a clinical challenge. A mouse model of hemophilia A can be used to test the efficacy of strategies for inhibitor suppression, but the differences in the immune systems of mice and humans limit its utility. To address this shortcoming, we established a humanized NOD/SCID-IL2rγnull hemophilia A (hu-NSG-HA) mouse model with a severely deficient mouse immune system presenting a patient's adapted immune cells. METHODS AND RESULTS: Through intrasplenic injection with patient inhibitor-positive peripheral blood mononuclear cells (PBMCs), utilizing an adeno-associated viral delivery system expressing human BLyS, and regular FVIII challenge, human C19+ B cells were expanded in vivo to secrete anti-FVIII antibodies. Both the inhibitor and the human anti-FVIII IgG, including the predominant subclasses (IgG1 and IgG4) present in the majority of inhibitor patients, were detected in the mouse model. We further segregated and expanded the different clones of human anti-FVIII-secreting cells through subsequent transplantation of splenocytes derived from hu-NSG-HA mice into another NSG-HA mouse. By transplanting a patient's PBMCs into the NSG-HA mouse model, we demonstrated the success of reintroducing a strong anti-FVIII immune response for a short period in mice with the immune systems of inhibitor-positive patients. CONCLUSION: Our results demonstrate a potential tool for directly obtaining functional human-derived antigen-specific antibodies and antibody-secreting cells, which may have therapeutic value for testing patient-specific immune responses to treatment options to assist in clinical decisions.

Osteopontine-derived functional fragments coupled to RADA16 self-assembled peptide hydrogels promotes bone and vascular regeneration in vivo.

Biomaterial scaffolds have been widely used in tissue engineering. A functionalized self-assembled peptide scaffold named RADA16-OPD was designed by linking the short functional motif of osteopontine (OPN)-derived functional fragments SVVYGLR (OPD) to the C-terminus of the self-assembled peptide RADA16. Atomic force microscopy (AFM) was used to analyze the self-assembling peptide's structural composition. The live/dead staining results showed that RADA16-OPD is not toxic to rASC. After creating a rat skull defect model artificially, micro-CT results revealed that the defect area treated with RADA16-OPD hydrogel had higher bone volume/total volume (BV/TV), a higher trabecular number (TB.N.), and higher bone density (BMD) at different treatment time points. Histological evaluation found that there was more new bone and mature collagen production in the RADA16-OPD group. Meanwhile, the RADA16-OPD group had higher expression of alkaline phosphatase (ALP) and osteocalcin (OCN) than the other two groups. Additionally, immunofluorescence revealed that the RADA16-OPD group had higher levels of platelet/endothelial cell adhesion molecule 1 (CD31) expression than the other two groups. It demonstrated the potential for clinical use of the RADA16-OPD peptide scaffold by promoting bone regeneration and blood vessel development in vivo.

Cluster analysis for the overall health status of elderly, multimorbid patients with diabetes.

Purpose: To evaluate the overall health status and health-related abilities and problems of elderly patients with diabetes and multimorbidity compared with those with diabetes only. Additionally, we aimed to identify different subgroups of elderly, multimorbid patients with diabetes. Methods: This cross-sectional study included 538 elderly patients with diabetes. The participants completed a series of questionnaires on self-rated health (SRH), diabetes self-management, self-efficacy, health literacy, depression, and diabetes distress. Differences in health-related abilities and problems were compared between elderly patients with diabetes and multimorbidity and those with diabetes only, with adjustments for covariates using propensity score matching. A cluster analysis was also performed to identify the overall health status subgroups of elderly, multimorbid patients with diabetes. Additionally, we conducted a multinomial logistic regression analysis to examine the predictors of health-related abilities and problem-cluster group membership. Results: Elderly patients with diabetes and multimorbidity experienced more health-related abilities and problems than those with diabetes only, particularly within the domains of depression (p < 0.001), and diabetes distress. The level of health literacy (p < 0.001) and self-management (p = 0.013) in elderly, multimorbid patients with diabetes was also significantly higher than that in elderly patients with diabetes only. Cluster analysis of elderly, multimorbid patients with diabetes revealed three distinct overall health status clusters. Multinomial logistic regression analysis indicated that age (OR = 1.090, p = 0.043), sex (OR = 0.503, p = 0.024), living situation (OR = 2.769, p = 0.011), BMI (OR = 0.838, p = 0.034), regular exercise (OR = 2.912, p = 0.041 in poor vs. good; OR = 3.510, p < 0.001 in intermediate vs. good), and cerebral infarction (OR = 26.280, p < 0.001) independently and significantly predicted cluster membership. Conclusion: Compared with elderly patients with diabetes only, those with diabetes and multimorbidity experienced more health-related abilities and problems within the domains of depression, and diabetes distress. Additionally, the level of health literacy and self-management in elderly, multimorbid patients with diabetes was significantly higher than that in those with diabetes only. Among the multimorbid diabetes group, old age, male sex, living without a partner, slightly lower BMIs, not exercising regularly, and experiencing cerebral infarctions were all positively correlated with worse overall health status.

Repair of critical-sized rat cranial defects with RADA16-W9 self-assembled peptide hydrogel.

Bone defects are common in orthopaedics and there is an urgent need to explore effective bone repair materials with osteoinductive activity. Peptide self-assembled nanomaterials have a fibrous structure like that of the extracellular matrix and are ideal bionic scaffold materials. In this study, a short peptide WP9QY (W9) with strong osteoinductive effect was tagged to a self-assembled peptide RADA16 molecule through solid phase synthesis to design a RADA16-W9 peptide gel scaffold. A rat cranial defect was used as a research model to explore the effect of this peptide material on the repair of bone defects in vivo. The structure characteristic of the functional self-assembling peptide nanofiber hydrogel scaffold RADA16-W9 was evaluated by atomic force microscopy (AFM). Then adipose stem cells (ASCs) were isolated from Sprague-Dawley (SD) rat and cultured. the cellular compatibility of scaffold was evaluated through Live/Dead assay. Furthermore, we explore the effects of hydrogels in vivo with the critical-sized mouse calvarial defect model. Micro-CT analysis showed that the RADA16-W9 group had higher levels of bone volume/total volume (BV/TV) (P < 0.05)，Trabecular number(TB.N) (P < 0.05)，bone mineral density (BMD)(P < 0.05) and trabecular thickness (Tb. Th) (P < 0.05) compared with the RADA16 and PBS groups. Hematoxylin and eosin (H&E) staining showed that RADA16-W9 group had the highest bone regeneration level. Histochemical staining showed significantly higher expression levels of osteogenic factors such as alkaline phosphatase (ALP) and osteocalcin (OCN) in the RADA16-W9 group than in the other two groups (P < 0.05). Reverse transcription polymerase chain reaction (RT-PCR) quantification showed higher mRNA expression levels of osteogenic-related genes ALP, Runt-related transcription factor 2(Runx2), OCN, Osteopontin (OPN) in the RADA16-W9 group than in the RADA16 and PBS groups (P < 0.05). The live/dead staining results showed that RADA16-W9 is not toxic to rASCs and has good biocompatibility. In vivo experiments show that it accelerates the process of bone reconstruction, significantly promoting bone regeneration and can be used to develop a molecular drug for bone defect repair.

Logistics Path Decision Optimization Method of Fresh Product Export Cold Chain Considering Transportation Risk.

The cold chain logistics route of fresh product export is characterized by large quantity and complexity, which is prone to cause transportation risks of different degrees in the process of fresh product export transportation and affects the decision-making effect of the cold chain logistics route. Therefore, in order to improve the ability of cold chain logistics route planning and shorten the transportation time, an optimization method of fresh product export cold chain logistics route decision considering transportation risk was proposed. This paper analyzes the basic characteristics and classification of cold chain logistics by means of risk quantification and uses the K-nearest neighbor algorithm to predict the risk of traffic congestion, so as to shorten the transportation time. Ahp process is used to construct a risk factor judgment matrix and determine the index weight of risk factors, so as to reduce the error of path planning. A genetic algorithm is introduced to construct the optimal decision function of the cold chain logistics route of new product export and realize the optimization of cold chain logistics route decision of fresh product export. Experimental results show that the method presented in this paper can effectively improve the decision-making effect of cold chain logistics route and select the shortest and most smooth transportation path to complete logistics distribution. The decision-making accuracy of the route decision effect is 90%, and the transportation time is 31.45 min, which has certain feasibility and applicability.

Using neutrophil to lymphocyte ratio to predict discharge among geriatric patients with influenza infection in emergency department.

The neutrophil-to-lymphocyte ratio (NLR) is used to predict the prognosis of various diseases, such as coronavirus disease 2019, community-acquired pneumonia, bacteremia, and endocarditis. However, NLR has never been reported to predict patient discharge in geriatric patients with influenza infection. This retrospective case-control study enrolled geriatric patients (≥65 years) with influenza virus infection who visited the emergency department of a medical center between January 01, 2010 and December 31, 2015. Demographic data, vital signs, past histories, influenza subtypes, outcomes, and disposition were analyzed. The optimal NLR cut-off value to predict patient discharge was determined using the Youden index. We also evaluated the accuracy of NLR in predicting patient discharge using logistic regression and receiver operating characteristic analysis. The study included 409 geriatric patients in the emergency department with a mean age of 79.5 years and an approximately equal sex ratio. NLR was significantly lower in the discharged group than in the nondischarged group (5.8 ± 3.7 vs 9.7 ± 8.4). Logistic regression revealed that patients with NLR ≤ 6.5 predicted discharge with an odds ratio of 3.62. The Hosmer-Lemeshow goodness-of-fit test was calculated as 0.36, and the adjusted area under the receiver operating characteristic was 0.75. The negative predictive value of NLR ≤ 6.5, to predict patient discharge, was 91.8%. NLR ≤ 6.5 is a simple and easy-to-obtain laboratory tool to guide the physicians to discharge geriatric patients with influenza infection in the crowded emergency department.

FECTS: A Facial Emotion Cognition and Training System for Chinese Children with Autism Spectrum Disorder.

Traditional training methods such as card teaching, assistive technologies (e.g., augmented reality/virtual reality games and smartphone apps), DVDs, human-computer interactions, and human-robot interactions are widely applied in autistic rehabilitation training in recent years. In this article, we propose a novel framework for human-computer/robot interaction and introduce a preliminary intervention study for improving the emotion recognition of Chinese children with an autism spectrum disorder. The core of the framework is the Facial Emotion Cognition and Training System (FECTS, including six tasks to train children with ASD to match, infer, and imitate the facial expressions of happiness, sadness, fear, and anger) based on Simon Baron-Cohen's E-S (empathizing-systemizing) theory. Our system may be implemented on PCs, smartphones, mobile devices such as PADs, and robots. The training record (e.g., a tracked record of emotion imitation) of the Chinese autistic children interacting with the device implemented using our FECTS will be uploaded and stored in the database of a cloud-based evaluation system. Therapists and parents can access the analysis of the emotion learning progress of these autistic children using the cloud-based evaluation system. Deep-learning algorithms of facial expressions recognition and attention analysis will be deployed in the back end (e.g., devices such as a PC, a robotic system, or a cloud system) implementing our FECTS, which can perform real-time tracking of the imitation quality and attention of the autistic children during the expression imitation phase. In this preliminary clinical study, a total of 10 Chinese autistic children aged 3-8 are recruited, and each of them received a single 20-minute training session every day for four consecutive days. Our preliminary results validated the feasibility of the developed FECTS and the effectiveness of our algorithms based on Chinese children with an autism spectrum disorder. To verify that our FECTS can be further adapted to children from other countries, children with different cultural/sociological/linguistic contexts should be recruited in future studies.

Lotus Bee Pollen Extract Inhibits Isoproterenol-Induced Hypertrophy via JAK2/STAT3 Signaling Pathway in Rat H9c2 Cells.

Bee pollen possesses an anti-cardiomyocyte injury effect by reducing oxidative stress levels and inhibiting inflammatory response and apoptosis, but the possible effect mechanism has rarely been reported. This paper explores the effect of the extract of lotus bee pollen (LBPE) on cardiomyocyte hypertrophy (CH) and its mechanism. The main components of LBPE were identified via UPLC-QTOF MS. An isoproterenol-induced rat H9c2 CH model was subsequently used to evaluate the protection of LBPE on cells. LBPE (100, 250 and 500 µg∙mL-1) reduced the surface area, total protein content and MDA content, and increased SOD activity and GSH content in CH model in a dose-dependent manner. Meanwhile, quantitative real-time PCR trials confirmed that LBPE reduced the gene expression levels of CH markers, pro-inflammatory cytokines and pro-apoptosis factors, and increased the Bcl-2 mRNA expression and Bcl-2/Bax ratio in a dose-dependent manner. Furthermore, target fishing, bioinformatics analysis and molecular docking suggested JAK2 could be a pivotal target protein for the main active ingredients in the LBPE against CH. Ultimately, Western blot (WB) trials confirmed that LBPE can dose-dependently inhibit the phosphorylation of JAK2 and STAT3. The results show that LBPE can protect against ISO-induced CH, possibly via targeting the JAK2/STAT3 pathway, also suggesting that LBPE may be a promising candidate against CH.

National Early Warning Score for predicting intensive care unit admission among elderly patients with influenza infections in the emergency department: an effective disposition tool during the influenza season.

OBJECTIVE: During the influenza epidemic season, the fragile elderlies are not only susceptible to influenza infections, but are also more likely to develop severe symptoms and syndromes. Such circumstances may pose a significant burden to the medical resources especially in the emergency department (ED). Disposition of the elderly patients with influenza infections to either the ward or intensive care unit (ICU) accurately is therefore a crucial issue. STUDY DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: Elderly patients (≥65 years) with influenza visiting the ED of a medical centre between 1 January 2010 and 31 December 2015. PRIMARY OUTCOME MEASURES: Demographic data, vital signs, medical history, subtype of influenza, national early warning score (NEWS) and outcomes (mortality) were analysed. We investigated the ability of NEWS to predict ICU admission via logistic regression and the receiver operating characteristic (ROC) analysis. RESULTS: We included 409 geriatric patients in the ED with a mean age of 79.5 years and approximately equal sex ratio. The mean NEWS ±SD was 3.4±2.9, and NEWS ≥8 was reported in 11.0% of the total patients. Logistic regression revealed that NEWS ≥8 predicted ICU admission with an OR of 5.37 (95% CI 2.61 to 11.04). The Hosmer-Lemeshow goodness-of-fit test was calculated as 0.95, and the adjusted area under the ROC was 0.72. An NEWS ≥8 is associated with ICU-admission and may help to triage elderly patients with influenza infections during the influenza epidemic season. CONCLUSION: The high specificity of NEWS ≥8 to predict ICU admission in elderly patients with influenza infection during the epidemic season may avoid unnecessary ICU admissions and ensure proper medical resource allocation.

A 12-hour rapid titration method for cancer pain: a randomized, controlled, open-label study.

BACKGROUND: Opioid titration is the best way to achieve a balance of pain relief and tolerable side effects for moderate-to-severe cancer pain. Rapid dose titration helps to achieve early analgesia. We explored the efficacy and safety of a 12-hour rapid dose titration in treating cancer pain. METHODS: Opioid-naïve patients with moderate-to-severe cancer pain were randomly divided into oxycodone group and morphine group. The medicines were adjusted to oxycodone sustained-release tablets after 12 hours, and the dose of oxycodone sustained-release tablets was adjusted every 12 hours. The analgesic efficacy and adverse reactions during the treatment were observed until the 72nd hour. RESULTS: A total of 106 patients were included in the analysis, with 51 patients in the oxycodone group and 55 in the morphine group. The pain control rate of all patients reached 96.2% 24 hours after treatment, and it was not significantly different between two groups (P=0.619). The proportion of Numeric Rating Scale (NRS) score that decreased by ≥50% was significantly higher in the oxycodone group than in the morphine group (P=0.013). In the first 12 hours and 24 hours, significantly lower proportions of patients in the oxycodone group experienced multiple episodes of breakthrough pain (BTP) than in the morphine group (P=0.032, P=0.021, respectively). The quality of life of the patients in the oxycodone group was significantly higher than that in the morphine group at the 24th hour (P=0.047), as was the degree to which the quality of life had improved (P<0.001). Only grade 1 or 2 adverse reactions were observed during the study period, and no significant difference between two groups. CONCLUSIONS: The 12-hour rapid dose titration method can achieve early analgesia, with mild adverse reactions. In particular, the rapid titration method with background sustained-release oxycodone can reduce BTP episodes and achieve significant early pain relief.

Schisandra chinensis bee pollen's chemical profiles and protective effect against H2O2-induced apoptosis in H9c2 cardiomyocytes.

BACKGROUND: Schisandra chinensis (Turcz.) Baill bee pollen extract (SCBPE) is often used as a functional food in China due to its good antioxidant property. However, its chemical compositions and effects on H9c2 cardiomyocytes against H2O2-induced cell injury still lacks of reports thus far. This study aimed to characterize the main components of SCBPE and investigate its protective effects against H2O2-induced H9c2 cardiomyocyte injury. METHODS: The main components of SCBPE were analyzed via ultraperformance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF MS/MS). The three main nucleosides in SCBPE were quantitatively analyzed via ultraperformance liquid chromatography-diode array detection. Furthermore, the potential mechanism by which SCBPE exerts protective effects against H2O2-induced H9c2 cardiomyocyte injury was explored for the first time via cell survival rate measurements; cell morphological observation; myocardial superoxide dismutase (SOD) activity and malondialdehyde (MDA) and glutathione (GSH) level determination; flow cytometry; and quantitative polymerase chain reaction. RESULTS: Two carbohydrates, three nucleosides, and nine quinic acid nitrogen-containing derivatives in SCBPE were identified or tentatively characterized via UPLC-QTOF MS/MS. The nine quinic acid nitrogen-containing derivatives were first reported in bee pollen. The contents of uridine, guanosine, and adenosine were 2.4945 ± 0.0185, 0.1896 ± 0.0049, and 1.8418 ± 0.0157 µg/mg, respectively. Results of in vitro experiments showed that cell survival rate, myocardial SOD activity, and GSH level significantly increased and myocardial MDA level significantly decreased in SCBPE groups compared with those in H2O2 group. Cell morphology in SCBPE groups also markedly improved compared with that in H2O2 group. Results indicated that SCBPE protected H9c2 cardiomyocytes from H2O2-induced apoptosis by downregulating the mRNA expressions of Bax, cytochrome C, and caspase-3 and upregulating the Bcl-2 mRNA expression. CONCLUSIONS: This study is the first to report that SCBPE could protect against oxidative stress injury and apoptosis in H2O2-injured H9c2 cells. Results indicated that the nucleosides and quinic acid nitrogen-containing derivatives could be the main substances that exert protective effects against H2O2-induced H9c2 cardiomyocyte injury.

Light-driven post-translational installation of reactive protein side chains.

Post-translational modifications (PTMs) greatly expand the structures and functions of proteins in nature1,2. Although synthetic protein functionalization strategies allow mimicry of PTMs3,4, as well as formation of unnatural protein variants with diverse potential functions, including drug carrying5, tracking, imaging6 and partner crosslinking7, the range of functional groups that can be introduced remains limited. Here we describe the visible-light-driven installation of side chains at dehydroalanine residues in proteins through the formation of carbon-centred radicals that allow C-C bond formation in water. Control of the reaction redox allows site-selective modification with good conversions and reduced protein damage. In situ generation of boronic acid catechol ester derivatives generates RH2C• radicals that form the native (ß-CH2-γ-CH2) linkage of natural residues and PTMs, whereas in situ potentiation of pyridylsulfonyl derivatives by Fe(II) generates RF2C• radicals that form equivalent ß-CH2-γ-CF2 linkages bearing difluoromethylene labels. These reactions are chemically tolerant and incorporate a wide range of functionalities (more than 50 unique residues/side chains) into diverse protein scaffolds and sites. Initiation can be applied chemoselectively in the presence of sensitive groups in the radical precursors, enabling installation of previously incompatible side chains. The resulting protein function and reactivity are used to install radical precursors for homolytic on-protein radical generation; to study enzyme function with natural, unnatural and CF2-labelled post-translationally modified protein substrates via simultaneous sensing of both chemo- and stereoselectivity; and to create generalized 'alkylator proteins' with a spectrum of heterolytic covalent-bond-forming activity (that is, reacting diversely with small molecules at one extreme or selectively with protein targets through good mimicry at the other). Post-translational access to such reactions and chemical groups on proteins could be useful in both revealing and creating protein function.

Selective voltammetric detection of chlorophylls using a semi-circular potential wave.

A simple electrochemical method employing a novel semi-circular potential sweep voltammetry on a glassy carbon (GC) electrode was developed to distinguish and quantify two main chlorophyll components (chlorophyll a and b) present in their mixtures. The semi-circular potential sweep generates large, transient scan rates, enabling the selective detection of species with closely similar oxidative potentials. The proposed method shows good applicability in mixtures of chlorophyll a (Chl a) and chlorophyll b (Chl b) with concentrations ranging from 46.2 to 110.8 µM and 46.2 to 92.4 µM respectively, which were prepared to mimic varying compositions of chlorophyll a and b in nature for the application in food quality control. The method was successfully applied to real sample of spinach.

Electrocatalysis via Intrinsic Surface Quinones Mediating Electron Transfer to and from Carbon Electrodes.

The electrochemistry of the Fe2+/Fe3+ redox couple in aqueous solution at carbon electrodes is shown to be catalyzed by surface quinone groups intrinsically present in the carbon surface. Such mediation has long been speculated but hitherto unproven.

Five-year medical expenses of central cord syndrome: analysis using a national cohort.

BACKGROUND: This study aimed to investigate the medical expenses and outcomes of central cord syndrome (CCS), comparing patients who received surgical and non-surgical management. METHODS: Using a 14-year nationwide database in Taiwan, this study followed-up all patients of CCS at least 5 years. The incidence rates, medical expenses, permanently disabled spinal cord injury (SCI), and mortality rates were compared for patients who underwent surgery and those who were managed conservatively. All CCS patients were further stratified by the level of injury (C1-4 vs. C5-7) in the cost analysis. RESULTS: A total of 1,753 patients with CCS were followed and the incidence of CCS was the highest among males aged between 60 and 70 years, at 42.4 per 1,000,000 person-years. The total medical expenses were higher in the surgery than the non-surgery group (46,586.9 vs. 28,472.4, P<0.001) because of rehabilitation. The surgery group had a significantly lower rate of mortality (Odds Ratio= 0.34, P<0.05) and lower rates of permanently disabled SCI (OR= 4.92, all P<0.001). CONCLUSIONS: The highest incidence rates of CCS were observed among males aged between 60 and 70 years. The expenses were higher but the mortality rate was lower for surgically managed patients. Further investigation is required to correlate the neurological outcomes to the management of CCS.

Serious dysphagia following anterior cervical discectomy and fusion: long-term incidence in a national cohort.

BACKGROUND: Although dysphagia is often self-limiting after anterior cervical discectomy and fusion (ACDF), its incidence, risks, and long-term outcomes remain unclear. The present study aimed to analyze dysphagia up to 5 years post-ACDF using a nation-scaled cohort. METHODS: Incidences of permanent dysphagia requiring nasogastric-tube feeding after ACDF were analyzed using three million-sample cohorts derived from the National Health Insurance Research Database of Taiwan. All identified subjects were stratified into four groups (40's, 50's, 60's, and >70) according to their age at operation, and were subsequently followed up for 5 years. The risks of dysphagia were compared between the groups using Kaplan-Meier analysis and Cox regression hazard ratio model. RESULTS: A total of 2723 patients (>40 years old) who received first-time ACDF surgery were identified from a cohort of three million and followed up for a maximum of 5 years post-operation. The 5-year incidence rates of persistent dysphagia (requiring use of a nasogastric tube) were 6.1, 4.0, 12.0, and 22.8 per 1000 person-years for each age group (40's, 50's, 60's, and 70+ years old, respectively). The overall incidence rate of dysphagia after ACDF was 18.4, 10.9, and 8.9 per 1000 person-years at 3 months, 1 year, and 5 years follow-up, respectively. The incidence rates of dysphagia and use of home care services were highest at 3 months postoperatively in all age groups, but dropped to a stable level after one year post-operation. The risks of dysphagia and the necessity of using home care services were higher (hazard ratio= 2.69 and 4.96) in the elderly group (aged 70 years and over) at all follow-up time points. CONCLUSIONS: The elderly patients had higher risks of short- and long-term severe dysphagia after ACDF. Therefore, although the incidence rates were still low (approximately 2.3%), older patients (aged 70 years and over) should be cautioned for dysphagia requiring a nasogastric tube and home care services if they undergo ACDF.

Dopamine oxidation at gold electrodes: mechanism and kinetics near neutral pH.

The two-electron electrochemical oxidation of dopamine is studied voltammetrically at gold macroelectrodes around neutral pH with simulations used to give kinetic and mechanistic data. In particular, the system shows "potential inversion" in which the thermodynamic oxidation potential of dopamine to form the corresponding semi-quinone formation occurs at a more positive potential than that of the oxidation of the semi-quinone to the quinone form. The use of Tafel slopes measured from the voltammograms as a function of the voltage scan rate is show to be a particularly sensitive indicator of mechanism showing the effect of the follow-up chemistry in which the two-electron oxidation product undergoes an irreversible cyclization reaction.

Electrochemical quantification of piperine in black pepper.

A simple, rapid method of the detection of piperine in black pepper is reported using a voltammetric sensor based on a glassy carbon (GC) electrode with analysis following a short one-step extraction using ethanol. The method is based on a novel potential sweep designed to maximise signal sizes and shown with context of the present analytical challenge to be essential for gathering data allowing the construction of a linear calibration curve for the analysis in the relevant range namely 0.25-5.0 mM.

Phase Difference Measurement of Under-Sampled Sinusoidal Signals for InSAR System Phase Error Calibration.

Phase difference measurement of sinusoidal signals can be used for phase error calibration of the spaceborne single-pass interferometric synthetic aperture radar (InSAR) system. However, there are currently very few papers devoted to the discussion of phase difference measurement of high-frequency internal calibration signals of the InSAR system, especially the discussion of sampling frequency selection and the corresponding measuring method when the high-frequency signals are sampled under the under-sampling condition. To solve this problem, a phase difference measurement method for high-frequency sinusoidal signals is proposed, and the corresponding sampling frequency selection criteria under the under-sampling condition is determined. First, according to the selection criteria, the appropriate under-sampling frequency was chosen to sample the two sinusoidal signals with the same frequency. Then, the sampled signals were filtered by limited recursive average filtering (LRAF) and coherently accumulated in the cycle of the baseband signal. Third, the filtered and accumulated signals were used to calculate the phase difference of the two sinusoidal signals using the discrete Fourier transform (DFT), digital correlation (DC), and Hilbert transform (HT)-based methods. Lastly, the measurement accuracy of the three methods were compared respectively by different simulation experiments. Theoretical analysis and experiments verified the effectiveness of the proposed method for the phase error calibration of the InSAR system.