Endogenous H2S-activated Ag nanoparticles embedded in programmed DNA-cubes for specific visualization of colorectal cancer cells.

To avoid the unexpected aggregation and reduce the cytotoxicity of nanomaterials as optical probes in cell imaging applications, we propose a programmed DNA-cube as a carrier for silver nanoparticles (Ag NPs) to construct a specific hydrogen sulfide (H2S) responsive platform (Ag NP@DNA-cube) for diagnosing colorectal cancer (CRC) in this study. The DNA-cube maintains good dispersion of Ag NPs while providing excellent biocompatibility. Based on the characteristic overexpression of endogenous H2S in CRC cells, the Ag NPs are etched by H2S within target cells into silver sulfide quantum dots, thereby selectively illuminating the target cells. The Ag NP@DNA-cube exhibits a specific fluorescence response to CRC cells and achieves satisfactory imaging.

Detection of Single Nucleotide Polymorphisms of Circulating Tumor DNA by Strand Displacement Amplification Coupled with Liquid Chromatography.

The detection of multiple single nucleotide polymorphisms (SNPs) of circulating tumor DNA (ctDNA) is still a great challenge. In this study, we designed enzyme-assisted nucleic acid strand displacement amplification combined with high-performance liquid chromatography (HPLC) for the simultaneous detection of three ctDNA SNPs. First, the trace ctDNA could be hybridized to the specially designed template strand, which initiated the strand displacement nucleic acid amplification process under the synergistic action of DNA polymerase and restriction endonuclease. Then, the targets would be replaced with G-quadruplex fluorescent probes with different tail lengths. Finally, the HPLC-fluorescence assay enabled the separation and quantification of multiple signals. Notably, this method can simultaneously detect both the wild type (WT) and mutant type (MT) of multiple ctDNA SNPs. Within a linear range of 0.1 fM-0.1 nM, the detection limits of BRAF V600E-WT, EGFR T790M-WT, and KRAS 134A-WT and BRAF V600E-MT, EGFR T790M-MT, and KRAS 134A-MT were 29, 31, and 11 aM and 22, 29, and 33 aM, respectively. By using this method, the mutation rates of multiple ctDNA SNPs in blood samples from patients with lung or breast cancer can be obtained in a simple way, providing a convenient and highly sensitive analytical assay for the early screening and monitoring of lung cancer.

Stimulating thyroglobulin to TSH ratio predict long-term efficacy of 131I therapy in patients with differentiated thyroid cancer after total thyroidectomy: a retrospective study.

OBJECTIVE: This study utilized the stimulated thyroglobulin (sTg) to thyroid stimulating hormone (TSH) ratio to predict the long-term efficacy of 131I therapy in patients with moderate-to-high-risk differentiated thyroid cancer (DTC). METHODS: This study retrospectively analyzed 960 DTC patients with a median follow-up time of 30 months (6-92 months). The median age was 44 years. All patients underwent total thyroidectomy, lymph node dissection, and at least one 131I therapy. Patients were subjected to a final efficacy evaluation according to American Thyroid Association's 2015 guidelines. Patients were grouped according to their TSH levels before the initial 131I therapy and the final efficacy evaluation, and factors influencing TSH levels and final efficacy were analyzed. Construction of nomograms using independent risk factors affecting long-term outcomes. The cut-offs of sTg and sTg/TSH ratios were calculated for different long-term outcomes. Progression-free survival (PFS) of patients was analyzed by making Kaplan-Meier survival according to the cut-offs of sTg and sTg/TSH ratio. RESULTS: TSH (mU/L) levels were more concentrated at 60-90 in females (71.5%) and 30-60 in males (39.0%), while patients with younger age, more lymph node metastases, shorter time interval between surgery and the first 131I therapy, and lower dose of levothyroxine sodium taken prior to the first 131I therapy would have higher TSH levels (All P < 0.05).Patients who are male, have primary tumor involvement of the strap muscles, lymph node metastasis, distant metastasis, and higher sTg and sTg/TSH are more likely to have poor long-term outcomes (All P < 0.05).The cut-offs of sTg and sTg/TSH for long-term efficacy were 7.515 and 0.095. STg, sTg/TSH, tumor size, lymph node metastasis, and distant metastasis were shown to be independent risk factors for long-term efficacy. The mean PFSs were longer for patients who had sTg/TSH ≤ 0.095 and/or sTg≤7.515 ug/L. CONCLUSIONS: For patients with moderate-to-high-risk DTC, when sTg>7.515 ug/L and/or sTg/TSH > 0.095 before the first 131I therapy, patients are more likely to have a poor long-term efficacy after full 131I therapy. This means that this group of patients may require further surgical treatment or targeted drug therapy after 131I therapy.

Multiplex Detection of Single Nucleotide Polymorphisms by Liquid Chromatography for Nonsmall Cell Lung Cancer Staging.

In this work, an integrated strategy with excellent accuracy and high throughput is proposed for the precise indication of single nucleotide polymorphism (SNP) in nonsmall cell lung cancer diseases. Two types of point mutations (L858R and T790M) and the corresponding wild types could be identified together in a single high-performance liquid chromatographic run. Signal amplification was achieved through a series of enzyme ligation, primer extension, and enzyme cleavage strategies, and a large number of DNA probes with different fluorescence signals were finally generated. The factors affecting the spatiotemporal separation efficiency of four DNA probes were systematically investigated. The limits of detection of wild types (WTs) or mutant types (MTs) abbreviated as L858R-MT, L858R-WT, T790M-MT, and T790M-WT were 26, 24, 19, and 22 aM, respectively. In addition, the levels of mutant types and wild types in the serum of 40 nonsmall cell lung cancer patients at different stages were detected using the method, and the correlation between the mutation ratios and cancer stages was preliminarily verified. The proposed highly selective and sensitive method may serve as an alternative approach for early diagnosis and staging of nonsmall cell lung cancer.

Clinical characteristics and therapeutic response of differentiated thyroid carcinoma with obesity and diabetes.

BACKGROUND: The effects of obesity and diabetes on the clinical outcomes of differentiated thyroid cancer (DTC) remain unclear. OBJECTIVES: To explore the association between obesity and diabetes with pathological features and therapeutic response of DTC. METHODS: Patients were categorized based on body mass index (BMI) and glycemic status. Compare the correlation between BMI and glycemic status with pathological features and therapeutic response of DTC. To analyze the independent risk factors for the aggressiveness of DTC. RESULTS: The proportion of patients with bilateral tumors was higher in the overweight, obese and diabetes group (P = 0.001, 0.045). The overweight group demonstrated a higher TNM stage (P = 0.004), while the T and TNM stages were higher in the diabetes group (P = 0.032, 0.000). The probability of distant metastasis increases by 37.4% for each unit of BMI increase (odds ratio (OR) = 1.374, CI 95% 1.061-1.778, P < 0.05). The BMI of Biochemical Incomplete Response (BIR) is significantly higher than that of Excellent Response (ER) (P = 0.015), the fasting plasma glucose (FPG) of Structural Incomplete (SIR) was significantly higher than that of ER and BIR (P = 0.030, 0.014). CONCLUSION: Obesity and diabetes have effect on DTC aggressiveness. BMI and FPG have correlation with the therapeutic response of DTC patients.

Fecal microbiota transplantation improves chicken growth performance by balancing jejunal Th17/Treg cells.

BACKGROUND: Intestinal inflammation has become a threatening concern in chicken production worldwide and is closely associated with Th17/Treg cell imbalance. Several studies described that gut microbiota is significantly implicated in chicken growth by modulating intestinal immune homeostasis and immune cell differentiation. Whether reshaping gut microbiota by fecal microbiota transplantation (FMT) could improve chicken growth by balancing Th17/Treg cells is an interesting question. RESULTS: Here, the chickens with significantly different body weight from three different breeds (Turpan cockfighting × White Leghorn chickens, white feather chickens, and yellow feather chickens) were used to compare Th17 and Treg cells. qPCR and IHC staining results indicated that Th17 cell-associated transcriptional factors Stat3 and rorγt and cytokines IL-6, IL-17A, and IL-21 were significantly (P < 0.05) higher in the jejunum of low body weight chickens, while Treg cell-associated transcriptional factor foxp3 and cytokines TGF-ß and IL-10 were significantly (P < 0.05) lower in the jejunum of low body weight chickens, indicating imbalanced Th17/Treg cells were closely related to chicken growth performance. Transferring fecal microbiota from the healthy donor with better growth performance and abundant Lactobacillus in feces to 1-day-old chicks markedly increased growth performance (P < 0.001), significantly decreased Th17 cell-associated transcriptional factors and cytokines, and increased Treg cell-associated transcriptional factors and cytokines in the jejunum (P < 0.05). Furthermore, FMT increased the abundance of Lactobacillus (FMT vs Con; 84.98% vs 66.94%). Besides, the metabolites of tryptophan including serotonin, indole, and 5-methoxyindoleacetate were increased as well, which activated their receptor aryl-hydrocarbon-receptor (AhR) and expressed more CYP1A2 and IL-22 to maintain Th17/Treg cell balance and immune homeostasis. CONCLUSION: These findings suggested that imbalanced Th17/Treg cells decreased chicken growth performance, while FMT-reshaped gut microbiota, i.e., higher Lactobacilli, increased chicken growth performance by balancing Th17/Treg cells. Video Abstract.

Mueller matrix imaging polarimeter at the wavelength of 265 nm.

Mueller matrix imaging polarimeters (MMIPs) have been developed in the wavelength region of >400n m with great potential in many fields yet leaving a void of instrumentation and application in the ultraviolet (UV) region. For the first time to our knowledge, an UV-MMIP is developed for high resolution, sensitivity, and accuracy at the wavelength of 265 nm. A modified polarization state analyzer is designed and applied to suppress stray light for nice polarization images, and the errors of the measured Mueller matrices are calibrated to lower than 0.007 in pixel level. The finer performance of the UV-MMIP is demonstrated by the measurements of unstained cervical intraepithelial neoplasia (CIN) specimens. The contrasts of depolarization images obtained by the UV-MMIP are dramatically improved over those obtained by our previous VIS-MMIP at the wavelength of 650 nm. A distinct evolution of depolarization in normal cervical epithelium tissue, CIN-I, CIN-II, and CIN-III specimens can be observed by the UV-MMIP with mean depolarization promotion by up to 20 times. This evolution could provide important evidence for CIN staging but can hardly be distinguished by the VIS-MMIP. The results prove that the UV-MMIP could be an effective tool in polarimetric applications with higher sensitivity.

Role of Exosomes in the Invasion and Metastasis of Ovarian Cancer and Application Potential of Clinical Diagnosis and Treatment.

Ovarian cancer is a highly lethal form of cancer in females, largely due to extensive metastases that often accompany the initial diagnosis. Exosomes are microvesicles size from 30 to 100nm, which can be secreted by most cells. These special extracellular vesicles play a vital role in the metastasis of ovarian cancer. In this study, we conducted a comprehensive review of current research pertaining to the role of exosomes in ovarian cancer, utilizing the PubMed® and Web of Science databases. Our review highlights the progress in elucidating the mechanisms by which exosomes facilitate ovarian cancer progression. Additionally, we discuss the potential of exosomes as a novel therapeutic target for ovarian cancer treatment. Overall, our review provides valuable insights into the current state of research on exosomes in ovarian cancer therapy.

Chicken cecal microbiota reduces abdominal fat deposition by regulating fat metabolism.

Cecal microbiota plays an essential role in chicken health. However, its contribution to fat metabolism, particularly in abdominal fat deposition, which is a severe problem in the poultry industry, is still unclear. Here, chickens at 1, 4, and 12 months of age with significantly (p < 0.05) higher and lower abdominal fat deposition were selected to elucidate fat metabolism. A significantly (p < 0.05) higher mRNA expression of fat anabolism genes (ACSL1, FADS1, CYP2C45, ACC, and FAS), a significantly (p < 0.05) lower mRNA expression of fat catabolism genes (CPT-1 and PPARα) and fat transport gene APOAI in liver/abdominal fat of high abdominal fat deposition chickens indicated that an unbalanced fat metabolism leads to excessive abdominal fat deposition. Parabacteroides, Parasutterella, Oscillibacter, and Anaerofustis were found significantly (p < 0.05) higher in high abdominal fat deposition chickens, while Sphaerochaeta was higher in low abdominal fat deposition chickens. Further, Spearman correlation analysis indicated that the relative abundance of cecal Parabacteroides, Parasutterella, Oscillibacter, and Anaerofustis was positively correlated with abdominal fat deposition, yet cecal Sphaerochaeta was negatively correlated with fat deposition. Interestingly, transferring fecal microbiota from adult chickens with low abdominal fat deposition into one-day-old chicks significantly (p < 0.05) decreased Parabacteroides and fat anabolism genes, while markedly increased Sphaerochaeta (p < 0.05) and fat catabolism genes (p < 0.05). Our findings might help to assess the potential mechanism of cecal microbiota regulating fat deposition in chicken production.

Three-dimensional ordered DNA network constructed by a biomarker pair for accurate monitoring of colorectal cancer.

Precise and early screening of colorectal cancer (CRC) is one crucial yet challenging task for its treatment, and the analysis of multi-targets of CRC in a single assay with high accuracy is essential for pathological research and clinical diagnosis. Here, a CRC-related biomarker pair, microRNA-211 (miRNA-211) and H2S, was detected by constructing a three-dimensional (3D) ordered DNA network. First, trace amount of miRNA-211 could initiate a hybridization chain reaction-based amplification process. A highly ordered 3D DNA network was formed based on the organized assembly of DNA-cube frameworks that were constructed by DNA origamis and Ag nanoparticles (NPs) encapsulated inside. In the presence of the H2S, Ag NPs within the network can be etched to generate Ag2S quantum dots, which could be better visualized in fluorescence in situ cell imaging. Using the 3D DNA ordered network as the sensing platform, it can acquire dual analysis of biomolecule (miRNA-211) and inorganic gas (H2S) in vitro, overcoming the limitations of single type of biomarker detection in a single assay. This assay achieved a wide linearity range of H2S from 0.05 to 10 µM, and exhibited a low limit of detection of 4.78 nM. This strategy allows us to acquire the spatial distributions of H2S and miRNA expression levels in living CRC cells simultaneously, providing a highly sensitive and selective tool for early screening and monitoring of CRC.

Self-Generation of Distinguishable Fluorescent Probes via a One-Pot Process for Multiple MicroRNA Detection by Liquid Chromatography.

To address the challenge of signal production and separation for multiple microRNA (miRNA) detection, in this work, a "one-pot" process to self-generate distinguishable fluorescent probes was developed. Based on a long and short probe amplification strategy, the generated G-quadruplex fluorescent dye-free probes can be separated and detected by a high-performance liquid chromatography-fluorescence platform. The free hairpin probes enriched in guanine with different lengths and base sequences were designed and could be opened by the target miRNAs (miRNA-10b, miRNA-21, and miRNA-210). Cleaved G-quadruplex probes with fluorescent signal could be generated in a one-pot process after a duplex-specific nuclease-based cleavage, and the detection of multiple miRNAs could be realized in one run. No solid nanomaterials were applied in the assay, which avoided the blocking of the column. Moreover, without modification of expensive fluorescein, the experimental cost was greatly reduced. The one-pot reaction process also eliminated tedious preparation steps and suggested feasibility of automation. The limits of detection of miRNA-10b, miRNA-21, and miRNA-210 were 2.19, 2.20, and 2.75 fM, respectively. Notably, this method was successfully applied to multiplex detection of miRNAs in serum samples from breast cancer patients within 30 min.

[Detection of four biogenic amines by liquid chromatography based on aptamer signal replacement combined with cyclic amplification].

Biogenic amines (BAs) represent a class of potentially harmful substances in foods and medicines. Their content is thus an important indicator of proper hygiene in food preparation, and purity of medicines. It is of great practical significance to establish accurate and sensitive detection of BAs in food and drugs. In this study, a high performance liquid chromatography (HPLC) method was developed for the simultaneous detection of multiple BAs in fish, pork and antibiotics based on aptamer signal replacement and cyclic amplification strategy. First, non-fluorescent targets were converted into fluorescent nucleic acid probes using a two-step replacement process. Subsequently, a large number of nucleic acid probes with different lengths and base sequences were generated using a double-stranded specific nuclease-assisted signal amplification strategy. Finally, various BAs in real samples were accurately identified using an HPLC platform. The influence of base sequence and nucleic acid probe length on separation via HPLC was studied to improve discrimination among fluorescent signals. Four different sequences were selected as tails to the DNA probe, and their retention times increased in turn. Experimental conditions, including column temperature, flow rate, gradient elution process, reaction temperature, and incubation time, were optimized by orthogonal experiments to further improve signal separation efficiency. Specifically, the methanol gradient was changed from 10% to 20% during 0-20 min, 35 ℃ of column temperature and 1.0 mL/min of flow rate were chosen as the HPLC conditions. The final resolution of chromatographic peaks was 3.44, 3.59 and 2.37, indicating complete separation between peaks. Optimal incubation time for BA capture by aptamer was 120 min, and optimal dosage of duplex specific nuclease (DSN) and Mg2+were 0.9 U and 30 mmol/L. The optimal pH, incubation temperature, and DSN incubation time were 7.0, 40 ℃ and 210 min, respectively. The proposed method exhibited high sensitivity towards BAs, with a linear range of 1 pmol/L-1 µmol/L, and the limits of detection of tyramine, histamine, spermine, and tryptamine were 0.25, 0.21, 0.27 and 0.19 pmol/L, respectively. The feasibility of this method was verified, and contrast experiments indicated that it could achieve highly selective detection of four BAs in one run. The applicability of this integrated method was also investigated for the detection of real samples (gentamycin sulfate, fish and pork). To assess the matrix effect, each BA with different concentrations were spiked into real fish and pork samples. Relative recoveries and relative standard deviations (RSDs) ranged from 101.2% to 104.5% and from 1.5% to 4.3%, respectively. The above detection results for real samples showed that this method could accurately capture, separate, and identify BAs in complex matrix samples. This strategy can effectively improve analyte selectivity and reduce the matrix effect. This assay is thus expected to provide a new approach for food and drug analyses.

V (Nb) Single Atoms Anchored by the Edge of a Graphene Armchair Nanoribbon for Efficient Electrocatalytic Nitrogen Reduction: A Theoretical Study.

Efficient and low-cost electrocatalysts are urgently required for the electrocatalytic N2 reduction reaction (NRR) to produce valuable NH3. Single-atom catalysts (SACs) represent one class of promising candidates. Besides the defects on the basal plane, very recently, the one-dimensional edge universally existing in the finite graphene or carbon sheet has gained attention as the anchoring site for SACs, which may enable unique catalytic mechanism. Herein, using first-principles calculations, we systematically investigated the NRR over SACs of transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Nb, Mo, and W) anchored by the N-modified edge of the graphene armchair nanoribbon (denoted as TM@GNR). Three criteria were employed to screen the best candidate from all the TM@GNR, including the high stability of TM@GNR, the preferable adsorption of N2 compared with H, and the lower applied potential for the first protonation of N2 compared with that of the active site. Accordingly, V(Nb)@GNR were theoretically demonstrated to be promising NRR electrocatalyst toward NH3 with low limiting potentials of -0.65 (-0.52) V, excellent selectivity of ∼100% (97%), and good stability. Particularly, NRR on the V@GNR and Nb@GNR precedes through a novel reaction mechanism with three spectator N2 molecules. Further analysis reveals that the strong capture and activation of N2 molecules by the edge-anchored V (Nb) atoms derives from their localized spin moment and atomic orbitals. Our studies emphasize the great potential of the edge of carbon materials to synthesize SACs for NRR and other reactions, and further reveal a novel NRR reaction mechanism on SACs.

Short Chain Fatty Acids (SCFAs) Are the Potential Immunomodulatory Metabolites in Controlling Staphylococcus aureus-Mediated Mastitis.

Mastitis is an emerging health concern in animals. An increased incidence of mastitis in dairy cows has been reported in the last few years across the world. It is estimated that up to 20% of cows are suffering from mastitis, causing incompetency in the mucosal immunity and resulting in excessive global economic losses in the dairy industry. Staphylococcus aureus (S. aureus) has been reported as the most common bacterial pathogen of mastitis at clinical and sub-clinical levels. Antibiotics, including penicillin, macrolides, lincomycin, cephalosporins, tetracyclines, chloramphenicol, and methicillin, were used to cure S. aureus-induced mastitis. However, S. aureus is resistant to most antibiotics, and methicillin-resistant S. aureus (MRSA) especially has emerged as a critical health concern. MRSA impairs immune homeostasis leaving the host more susceptible to other infections. Thus, exploring an alternative to antibiotics has become an immediate requirement of the current decade. Short chain fatty acids (SCFAs) are the potent bioactive metabolites produced by host gut microbiota through fermentation and play a crucial role in host/pathogen interaction and could be applied as a potential therapeutic agent against mastitis. The purpose of this review is to summarize the potential mechanism by which SCFAs alleviate mastitis, providing the theoretical reference for the usage of SCFAs in preventing or curing mastitis.

A Two-Stage Selective Fusion Framework for Joint Intent Detection and Slot Filling.

Spoken language understanding (SLU) is the core of the speech-centric human-robot interaction system, which mainly involves intent detection and slot filling. The recent SLU research focuses on the joint modeling of the two tasks due to their correlation. Furthermore, the slot information consists of slot position and slot type. Although the slot types are semantically related to the intent, the slot positions of the same intent may vary a lot in different utterances due to the diversity of spoken language. Thus, the conventional one-stage slot filling task may introduce unrelated information for slot position prediction in the slot-intent interaction of the joint modeling. Therefore, we propose a novel two-stage selective fusion framework for joint intent detection and slot filling. Unlike the previous one-stage framework, the proposed framework decomposes the slot filling into two stages, i.e., the slot proposal and slot classification. The slot proposal network consisting of BERT and bidirectional long short-term memory (Bi-LSTM)-conditional random field (CRF) predicts the slot positions. Instead of the tokenwise fusion in the existing methods, the slot-intent feature fusion is only performed in the slot classification. A selective fusion mechanism is designed to facilitate the slot-intent interaction within each slot candidate for more accurate slot-type classification. Experiments on five standard benchmarks (i.e., ATIS, SNIPS, MixATIS, MixSNIPS, and DSTC4) show that the proposed framework achieves the best performance in comparison with several state-of-the-art methods.

Chicken jejunal microbiota improves growth performance by mitigating intestinal inflammation.

BACKGROUND: Intestinal inflammation is prevalent in chicken, which results in decreased growth performance and considerable economic losses. Accumulated findings established the close relationship between gut microbiota and chicken growth performance. However, whether gut microbiota impacts chicken growth performance by lessening intestinal inflammation remains elusive. RESULTS: Seven-weeks-old male and female chickens with the highest or lowest body weights were significantly different in breast and leg muscle indices and average cross-sectional area of muscle cells. 16S rRNA gene sequencing indicated Gram-positive bacteria, such as Lactobacilli, were the predominant species in high body weight chickens. Conversely, Gram-negative bacteria, such as Comamonas, Acinetobacter, Brucella, Escherichia-Shigella, Thermus, Undibacterium, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium were significantly abundant in low body weight chickens. Serum lipopolysaccharide (LPS) level was significantly higher in low body weight chickens (101.58 ± 5.78 ng/mL) compared with high body weight chickens (85.12 ± 4.79 ng/mL). The expression of TLR4, NF-κB, MyD88, and related inflammatory cytokines in the jejunum was significantly upregulated in low body weight chickens, which led to the damage of gut barrier integrity. Furthermore, transferring fecal microbiota from adult chickens with high body weight into 1-day-old chicks reshaped the jejunal microbiota, mitigated inflammatory response, and improved chicken growth performance. CONCLUSIONS: Our findings suggested that jejunal microbiota could affect chicken growth performance by mitigating intestinal inflammation. Video Abstract.

Gut microbiota-derived short chain fatty acids are potential mediators in gut inflammation.

Gut inflammation is a challenging concern in humans and animals, which disturbs normal growth and leads to severe bowel diseases. Short chain fatty acids (SCFA) are the gut microbiota metabolites produced from fermentation of non-digestible carbohydrates, and have been reported to modulate gut inflammation. SCFA have been implicated as the potential therapeutic bioactive molecules for gut inflammatory diseases, and could be an alternative to antibiotic growth promoters (AGP). In this review, the existing knowledge about the types of SCFA, the related gut microbes producing SCFA, the roles of SCFA in maintaining gut homeostasis, and how SCFA modulate gut inflammation is summarized. The therapeutic application of SCFA in the treatment of inflammatory bowel disease (IBD) is also highlighted.

Electrocatalytic two-electron oxygen reduction over nitrogen doped hollow carbon nanospheres.

The two-electron oxygen reduction reaction (2e- ORR) has become a hopeful alternative for production of hydrogen peroxide (H2O2), but its practical feasibility is hindered by the lack of efficient electrocatalysts to achieve high activity and selectivity. Herein, we successfully synthesized outstanding nitrogen doped hollow carbon nanospheres (NHCSs) for electrochemical production of H2O2. In 0.1 M KOH, NHCSs exhibit superior and sustained catalytic activity for the 2e- ORR with an unordinary selectivity of 96.6%. Impressively, such NHCSs manifest an ultrahigh H2O2 yield rate of 7.32 mol gcat.-1 h-1 and a high faradaic efficiency of 96.7% at 0.5 V in an H-cell system. Density functional theory calculations were performed to further reveal the catalytic mechanism involved.

Holistic and efficient calibration method for Mueller matrix imaging polarimeter with a high numerical aperture.

High-numerical aperture (N A>0.6) Mueller matrix imaging polarimeter (MMIP) (high-NA MMIP) is urgently needed for higher resolution. Usually, the working distance of high-NA MMIP is too short to perform in situ calibration by a usual reference sample, such as polarizer and retarder plates. The polarization effects of the substrate that attach the sample are never calibrated. So, the resolution and accuracy of the MMIP is hard to further promote. In this paper, a holistic and efficient calibration method is innovated for high-NA MMIP. Two film polarizers and a film retarder as well as a blank substrate are first adopted as the reference samples in calibration. Different from the conventional eigenvalue calibration method (ECM), the holistic calibration theory and process are established. All polarimetric errors arising from the devices, subsystems, and the substrate can be calibrated in one process. The normalized measurement error is less than 0.0024 for NA 0.95 MMIP, which is an order of magnitude lower than those of NA 0.1 and 0.2 MMIPs in publications. The excellent performance of calibrated high-NA MMIP is demonstrated by tissue polarimetry with higher resolution, accuracy, and more appropriate dynamic range.