Phase change material composites based on 3D lignin-derived porous carbon prepared by in-situ activation for efficient solar-driven energy conversion and storage.

Utilization of three-dimensional biomass-derived porous carbons can effectively address issues of easy leakage, low thermal conductivity, and weak photothermal conversion of phase change materials (PCMs). This enables the production of high-performance composites for solar-induced energy collection, conversion, and storage. In this study, hierarchical lignin-derived porous carbon (HLPC), microporous lignin-derived porous carbon (MILPC) and mesoporous lignin-derived porous carbon (MELPC) were prepared through high-temperature in-situ activation using lignosulphonate (LS) as a carbon precursor and CaCO3, KOH and ZnCO3 as activators. Carbon-based PCM composites with high performance were obtained by encapsulating paraffin wax (PW) in porous carbon supports. Results demonstrated that PW/HLPC exhibited comprehensive performance superior to other tested PW composites owing to its higher specific surface area (2,358 m2/g), larger pore volume (1.1 cm3/g) and well-interconnected framework structure. Additionally, PW/HLPC displayed relatively high latent heat (123.4 kJ/kg), photothermal conversion and storage efficiency (95 %), and photoelectric conversion performance (174.5 mV). Moreover, PW/HLPC also showed better leak-proof properties at 90 °C. The cycling stability and photothermal conversion performance of PW/HLPC were superior to those of the selected crude biochar-based PW composites. This study highlights the advantages of the prepared PW/HLPC for both the high-value utilization of lignin and its practical applications in solar-induced energy harvest, conversion, and storage.

2-Methylbenzimidazole-copper nanozyme with high laccase activity for colorimetric differentiation and detection of aminophenol isomers.

Laccase is well-known for its eco-friendly applications in environmental remediation and biotechnology, but its high cost and low stability have limited its practical use. Therefore, there is an urgent need to develop efficient laccase mimetics. In this study, a novel laccase-mimicking nanozyme (MBI-Cu) was successfully synthesized using 2-methylbenzimidazole (MBI) coordinated with Cu2+ by mimicking the copper active site and electron transfer pathway of natural laccase. MBI-Cu nanozyme exhibited excellent catalytic activity and higher stability than laccase, and was utilized to oxidize a series of phenolic compounds. Environmental pollutant aminophenol isomers were found to display different color in solution when catalytically oxidized by MBI-Cu, which provided a simple and feasible method to identify them by the naked eye. Based on the distinct absorption spectra of the oxidized aminophenol isomers, a colorimetric method for quantitatively detecting o-AP, m-AP, and p-AP was established, with detection limits of 0.06 µM, 0.27 µM, and 0.18 µM, respectively. Furthermore, by integrating MBI-Cu-based cotton pad colorimetric strips with smartphone and utilizing color recognition software to identify and analyze the RGB values of the images, a portable colorimetric sensing platform was designed for rapid detection of aminophenol isomers without the need for any analytical instrument. This work provides an effective reference for the design of laccase nanozymes and holds significant potential for applications in the field of environmental pollutant monitoring.

Metronomic chemotherapy plus anti-PD-1 in metastatic breast cancer: a Bayesian adaptive randomized phase 2 trial.

It remains unclear whether metronomic chemotherapy is superior to conventional chemotherapy when combined with immune checkpoint blockade. Here we performed a phase 2 clinical trial of metronomic chemotherapy combined with PD-1 blockade to compare the efficacy of combined conventional chemotherapy and PD-1 blockade using Bayesian adaptive randomization and efficacy monitoring. Eligible patients had metastatic HER2-negative breast cancer and had not received more than one prior line of standard chemotherapy. Patients (total n = 97) were randomized to receive (1) metronomic vinorelbine (NVB) monotherapy (n = 11), (2) NVB plus anti-PD-1 toripalimab (n = 7), (3) anti-angiogenic bevacizumab, NVB and toripalimab (n = 27), (4) conventional cisplatin, NVB and toripalimab (n = 26), or (5) metronomic cyclophosphamide, capecitabine, NVB and toripalimab (the VEX cohort) (n = 26). The primary endpoint was disease control rate (DCR). Secondary objectives included progression-free survival (PFS) and safety. The study met the primary endpoint. The VEX (69.7%) and cisplatin (73.7%) cohorts had the highest DCR. The median PFS of patients in the VEX cohort was the longest, reaching 6.6 months, followed by the bevacizumab (4.0 months) and cisplatin (3.5 months) cohorts. In general, the five regimens were well tolerated, with nausea and neutropenia being the most common adverse events. An exploratory mass cytometry analysis indicated that metronomic VEX chemotherapy reprograms the systemic immune response. Together, the clinical and translational data of this study indicate that metronomic VEX chemotherapy combined with PD-1 blockade can be a treatment option in patients with breast cancer. ClinicalTrials.gov Identifier: NCT04389073 .

A retrospective study on the prevalence and risk factors of neurogenic lower urinary tract dysfunction for acute ischemic stroke in China: A case-control study.

PURPOSE: This study identified risk factors for neurogenic lower urinary tract dysfunction (NLUTD) in patients with acute ischemic stroke (AIS) through multidimensional analysis of the medical records of patients, aiming to reduce the incidence of NLUTD, improve prognosis, and facilitate rehabilitation. MATERIALS AND METHODS: In this case-control study, patients with AIS were recruited from two tertiary general hospitals in Shenzhen, China, from March 2021 to October 2023. Patients were divided into NLUTD and non-NLUTD groups based on the presence and absence of NLUTD, respectively. Comparative analysis was performed using the Mann-Whitney U and chi-square tests, with significant variables being included in logistic regression analysis. RESULTS: Of the 652 participants enrolled in this study, 119 participants (18.3%) developed NLUTD. Bivariate analysis showed that 39 of 54 screened factors exhibited a significant correlation (p<0.05) with the incidence of NLUTD after AIS. Significant variables identified through logistic regression analysis included Glasgow coma scale (GCS) and National Institutes of Health Stroke Scale (NIHSS) scores, anemia, aphasia, pneumonia, brainstem involvement, multiple lesions, urine clarity (CLA), random venous blood glucose (GLU) and hemoglobin (HGB) levels, and white blood cell (WBC) count. CONCLUSIONS: A total of 11 risk factors for NLUTD were identified in this study. This finding provides valuable guidance for reducing the incidence of NLUTD after AIS and improving the quality of life of patients.

A nomogram for predicting neurogenic lower urinary tract dysfunction in patients with acute ischemic stroke: A retrospective study.

AIMS: To investigate the risk factors for neurogenic lower urinary tract dysfunction (NLUTD) in patients with acute ischemic stroke (AIS), and develop an internally validated predictive nomogram. The study aims to offer insights for preventing AIS-NLUTD. METHODS: We conducted a retrospective study on AIS patients in a Shenzhen Hospital from June 2021 to February 2023, categorizing them into non-NLUTD and NLUTD groups. The bivariate analysis identified factors for AIS-NLUTD (p < 0.05), integrated into a least absolute shrinkage and selection operator (LASSO) regression model. Significant variables from LASSO were used in a multivariate logistic regression for the predictive model, resulting in a nomogram. Nomogram performance and clinical utility were evaluated through receiver operating characteristic curves, calibration curves, decision curve analysis (DCA), and clinical impact curve (CIC). Internal validation used 1000 bootstrap resamplings. RESULTS: A total of 373 participants were included in this study, with an NLUTD incidence rate of 17.7% (66/373). NIHSS score (OR = 1.254), pneumonia (OR = 6.631), GLU (OR = 1.240), HGB (OR = 0.970), and hCRP (OR = 1.021) were used to construct a predictive model for NLUTD in AIS patients. The model exhibited good performance (AUC = 0.899, calibration curve p = 0.953). Internal validation of the model demonstrated strong discrimination and calibration abilities (AUC = 0.898). Results from DCA and CIC curves indicated that the prediction model had high clinical utility. CONCLUSIONS: We developed a predictive model for AIS-NLUTD and created a nomogram with strong predictive capabilities, assisting healthcare professionals in evaluating NLUTD risk among AIS patients and facilitating early intervention.

Stable peptide-assembled nanozyme mimicking dual antifungal actions.

Natural antimicrobial peptides (AMPs) and enzymes (AMEs) are promising non-antibiotic candidates against antimicrobial resistance but suffer from low efficiency and poor stability. Here, we develop peptide nanozymes which mimic the mode of action of AMPs and AMEs through de novo design and peptide assembly. Through modelling a minimal building block of IHIHICI is proposed by combining critical amino acids in AMPs and AMEs and hydrophobic isoleucine to conduct assembly. Experimental validations reveal that IHIHICI assemble into helical ß-sheet nanotubes with acetate modulation and perform phospholipase C-like and peroxidase-like activities with Ni coordination, demonstrating high thermostability and resistance to enzymatic degradation. The assembled nanotubes demonstrate cascade antifungal actions including outer mannan docking, wall disruption, lipid peroxidation and subsequent ferroptotic death, synergistically killing >90% Candida albicans within 10 min on disinfection pad. These findings demonstrate an effective de novo design strategy for developing materials with multi-antimicrobial mode of actions.

Mechanism study of aging oil demulsification and dehydration under ultrasonic irradiation.

With the tertiary oil recovery in the oilfield, the content of aging oil emulsion with high water content and complex components has become more prevalent, so it is crucial for aging oil to break the emulsification. In this paper, the experimental laws of water content are explored under the conditions of different transducer input powers through the ultrasonic reforming of aging oil, and the microscopic topography, particle size, components, etc. of oil samples before and after the irradiation of ultrasound are characterized through the microscopic analysis, particle size analysis and component analysis and other ways. The results show that the oil samples achieve the effect of demulsification and dehydration in the presence of ultrasonic cavitation effect, with a maximum dehydration rate of 98.24 %, and that the dehydration rate follows an "M-type" trend with the increase of power. The results of microscopic and particle size analyses demonstrate that ultrasonic irradiation destabilizes the oil-water interfacial membrane, and causes droplets of different sizes to collide, agglomerate, and settle. It was also observed that the droplets of the emulsion system are more evenly distributed and the intervals are increased. Furthermore, we hypothesize that ultrasound may be less irreversible in demulsification and dehydration of aging oil.

Discovery of TRPA1 Antagonist GDC-6599: Derisking Preclinical Toxicity and Aldehyde Oxidase Metabolism with a Potential First-in-Class Therapy for Respiratory Disease.

Transient receptor potential ankyrin 1 (TRPA1) is a nonselective calcium ion channel highly expressed in the primary sensory neurons, functioning as a polymodal sensor for exogenous and endogenous stimuli, and has been implicated in neuropathic pain and respiratory disease. Herein, we describe the optimization of potent, selective, and orally bioavailable TRPA1 small molecule antagonists with strong in vivo target engagement in rodent models. Several lead molecules in preclinical single- and short-term repeat-dose toxicity studies exhibited profound prolongation of coagulation parameters. Based on a thorough investigative toxicology and clinical pathology analysis, anticoagulation effects in vivo are hypothesized to be manifested by a metabolite─generated by aldehyde oxidase (AO)─possessing a similar pharmacophore to known anticoagulants (i.e., coumarins, indandiones). Further optimization to block AO-mediated metabolism yielded compounds that ameliorated coagulation effects in vivo, resulting in the discovery and advancement of clinical candidate GDC-6599, currently in Phase II clinical trials for respiratory indications.

Targeting the mammalian target of rapamycin pathway in neurological manifestations of Covid-19.

The diverse and severe nature of neurological manifestations associated with coronavirus disease 2019 (Covid-19) has garnered increasing attention. Exploring the potential to decrease neurological complications in Covid-19 patients involves targeting the mammalian target of rapamycin (mTOR) pathway as a therapeutic strategy. The mTOR pathway, widely recognised for its central role in essential cellular processes like synthesising proteins, facilitating autophagy, and modulating immune responses, has implications in various neurological disorders. Drawing parallels between these disorders and the observed neurological complications in Covid-19, we present a comprehensive review on the current understanding of mTOR signalling in the context of severe acute respiratory syndrome coronavirus 2 infection and neuroinflammation.

The Realities and Needs of Nursing Assistants Caring for Disabled Patients with Fecal Incontinence During Hospitalization: A Qualitative Study.

Objective: To explore the experience, role, and needs of medical nursing assistants during hospitalization in patients with incapacitated fecal incontinence. Methods: Qualitative study using reflexive thematic analysis. Semi-structured interviews were conducted with 21 medical nursing assistants from three hospitals in Southern China. Results: Four themes were constructed from the data: (1) Role perception. All participants described the multiple roles they played during care and knowledge and familiarity with the roles were seen as providing high-quality care to patients. (2) Career cognition. Overall, participants had a positive view of nurse assistants as a career. They believed that nursing experience was more important than training. (3) emotional belonging. The multiple roles of medical nursing assistants give them very mixed emotions. (4) Potential needs. Participants reported that the fatigue of repeatedly scrubbing and cleaning stools, the negative emotions that could not be faced and resolved, and their special status made them overwhelmed, potentially reflecting that they needed more support. Conclusions: This study highlights the roles, experiences, confusions, and needs of nursing assistants in caring for patients with disabling fecal incontinence. Suggested areas for improvement include the development of more intelligent fecal incontinence collection devices and the development of management and training strategies by health managers based on the specific context of medical nursing assistants to emphasize the role of medical nursing assistants and improve the quality of clinical care.

Zoledronic acid and ibandronate-induced nephrotoxicity in 2D and 3D proximal tubule cells derived from human and rat.

Drug-induced proximal tubule (PT) injury remains a serious safety concern throughout drug development. Traditional in vitro 2-dimensional (2D) and preclinical in vivo models often fail to predict drug-related injuries presented in clinical trials. Various 3-dimensional (3D) microphysiological systems (MPSs) have been developed to mimic physiologically relevant properties, enabling them to be more predictive toward nephrotoxicity. To explore the capabilities of an MPS across species, we compared cytotoxicity in hRPTEC/TERT1s and rat primary proximal tubular epithelial cells (rPPTECs) following exposure to zoledronic acid and ibandronate (62.5-500 µM), and antibiotic polymyxin B (PMB) (50 and 250 µM, respectively). For comparison, we investigated cytotoxicity using 2D cultured hRPTEC/TERT1s and rPPTECs following exposure to the same drugs, including overlapping concentrations, as their 3D counterparts. Regardless of the in vitro model, bisphosphonate-exposed rPPTECs exhibited cytotoxicity quicker than hRPTEC/TERT1s. PMB was less sensitive toward nephrotoxicity in rPPTECs than hRPTEC/TERT1s, demonstrating differences in species sensitivity within both 3D and 2D models. Generally, 2D cultured cells experienced faster drug-induced cytotoxicity compared to the MPSs, suggesting that MPSs can be advantageous for longer-term drug-exposure studies, if warranted. Furthermore, ibandronate-exposed hRPTEC/TERT1s and rPPTECs produced higher levels of inflammatory and kidney injury biomarkers compared to zoledronic acid, indicating that ibandronate induces acute kidney injury, but also a potential protective response since ibandronate is less toxic than zoledronic acid. Our study suggests that the MPS model can be used for preclinical screening of compounds prior to animal studies and human clinical trials.

A Key-Points Based Anchor-Free Cervical Cell Detector.

Cervical cell detection is crucial to cervical cytology screening at early stage. Currently most cervical cell detection methods use anchor-based pipeline to achieve the localization and classification of cells, e.g. faster R-CNN and YOLOv3. However, the anchors generally need to be pre-defined before training and the detection performance is inevitably sensitive to these pre-defined hyperparameters (e.g. number of anchors, anchor size and aspect ratios). More importantly, these preset anchors fail to conform to the cells with different morphology at inference phase. In this paper, we present a key-points based anchor-free cervical cell detector based on YOLOv3. Compared with the conventional YOLOv3, the proposed method applies a key-points based anchor-free strategy to represent the cells in the initial prediction phase instead of the preset anchors. Therefore, it can generate more desirable cell localization effect through refinement. Furthermore, PAFPN is applied to enhance the feature hierarchy. GIoU loss is also introduced to optimize the small cell localization in addition to focal loss and smooth L1 loss. Experimental results on cervical cytology ROI datasets demonstrate the effectiveness of our method for cervical cell detection and the robustness to different liquid-based preparation styles (i.e. drop-slide, membrane-based and sedimentation).

Reproducibility and usefulness of quantitative apparent diffusion coefficient measurements for predicting program death-ligand 1 expression in nasopharyngeal carcinoma.

BACKGROUND: Accurate assessment of programmed death-ligand 1 (PD-L1) expression status in nasopharyngeal carcinoma (NPC) before immunotherapy is crucial. We aimed to explore the reproducibility and usefulness of the quantitative apparent diffusion coefficient (ADC) measurements for predicting PD-L1expression status in NPC. METHODS: We retrospectively recruited 134 NPC patients who underwent MRI scans and PD-L1 detection. A PD-L1 combined positive score (CPS) ≥ 20 was identified as high expression status. Patients were divide into two cohorts based on the MRI scanning devices, including a 1.5-T MRI cohort (n = 85, 44 PD-L1 high expression) and a 3.0-T MRI cohort (n = 49, 24 PD-L1 high expression). The mean ADC (ADCmean), minimum ADC (ADCmin) and maximal ADC (ADCmax) values were independently measured by two observers. The ADC measurement reproducibility was assessed by interclass correlation coefficients (ICC). The correlations between ADC parameters and CPS were analyzed by spearman's correlation coefficient (r), and the performance for PD-L1expression status prediction was assessed by the area under receiver operating characteristic curve (AUC). RESULTS: The measurement reproducibility of ADCmean, ADCmin and ADCmax was good in the 1.5-T MRI cohort (ICC: 0.843-0.930) and 3.0-T MRI cohort (ICC: 0.929-0.960). The ADCmean, ADCmin, and ADCmax tended to inversely correlate with the CPS (r:-0.37 - -0.52 in the 1.5-T MRI cohort, and - 0.52 - -0.60 in the 3.0-T MRI cohort; P all < 0.01). The ADCmean, ADCmin and ADCmax yielded the AUC of 0.756 (95% CI: 0.651, 0.861), 0.689 (95% CI: 0.576, 0.802), and 0.733 (95%CI: 0.626, 0.839) in the 1.5-T MRI cohort and 0.820 (95%CI: 0.703, 0.937), 0.755 (95% CI: 0.616, 0.894), and 0.760 (95%CI: 0.627, 0.893) in the 3.0-T MRI cohort for predicting PD-L1 high expression status, respectively. CONCLUSION: ADC measurements may act as a reproducible and feasible method to predict PD-L1 expression status in NPC.

Development and validation of a Decision-Making Ability Scale for postpartum urinary incontinence women engaging in pelvic floor physical therapy.

OBJECTIVE: This study aimed to develop and validate a Decision-Making Ability Scale (DMA-S) for postpartum urinary incontinence (PPUI) women engaging in pelvic floor physical therapy (PFPT). METHODS: Items were created in line with a review of the literature and exploratory qualitative study with 22 women. The items were submitted for expert opinion and a pilot implementation was made with 58 women with PPUI. Furthermore, the construct validity of the scale was tested with exploratory factor analysis (EFA) (n = 220) and confirmatory factor analysis (CFA) (n = 240). Internal consistency for the Chronbach's α and test-retest reliability for the intraclass correlation coefficient (ICC) were also investigated for the DMA-S in the study. RESULTS: The results of the EFA indicated a Kaiser-Meyer-Olkin value of 0.85 and Bartlett's test of sphericity showed a χ2 value of 8352.101, p < 0.001. After removing one item with factor loading values below 0.50, the resulting factor structure accounted for 83.38% of the total variance. The fit indices of the scale model tested in the CFA were determined as χ2 /df = 1.08 < 3, root mean square error of approximation = 0.018 < 0.08, comparative fit index = 0.996 > 0.90, Tucker-Lewis index = 0.995 > 0.90, goodness-of-fit index (GFI) = 0.933 > 0.90, adjusted GFI = 0.916 > 0.90, and incremental fit index = 0.996 > 0.90. The Cronbach's α values were 0.95-0.97 for the subdimensions of the scale and 0.93 for the total scale. Data also showed a good test-retest stability (ICC = 0.984). CONCLUSION: The DMA-S is a reliable and valid tool for assessing the decision-making ability for PPUI women engaging in PFPT.

The roles of lncRNAs in Th17-associated diseases, with special focus on JAK/STAT signaling pathway.

One of the most crucial T cell subsets in a variety of autoimmune and chronic inflammatory illnesses is T helper (Th) 17 cells. Th17 cells appear to have an essential role in the clearance of extracellular pathogens during infections. However, Th17 cells are also involved in inflammation and have been implicated in the pathogenesis of several autoimmune diseases and human inflammatory conditions. Due to the involvement of Th17 cells in the onset of Th17-associated diseases, understanding molecular mechanisms of Th17 cell functions may open the door to developing tailored therapies to address these difficult disorders. However, the molecular mechanisms governing Th17 differentiation in various diseases are still not well understood. The JAK/STAT signaling pathway plays a critical role in immune responses and has been linked to various aspects of Th17 cell differentiation and function. In this article, we conducted a comprehensive review of various molecular mechanisms (JAK/STAT, microRNAs, etc.), that can affect the differentiation of Th17 cells in various Th17-associated diseases.

Development and Validation of Nutrition Literacy Assessment Instrument for Chinese Lactating Women: A Preliminary Study.

This study focused on the development and validation of a nutrition literacy assessment instrument for Chinese lactating women (NLAI-L). A comprehensive literature review and group discussion by experts in relevant fields were adopted to determine the dimension, topics and questions of NLAI-L. Content validity was evaluated by a panel of experts. The exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) were used to evaluate the construct validity. Cronbach's α and split-half reliability were applied to examine the reliability of NLAI-L. The final NLAI-L consisted of 38 questions covering three dimensions: knowledge, behavior and skill. The EFA revealed four sub-domains for knowledge, one sub-domain for behavior and four sub-domains for skill. The results showed that NLAI-L had satisfactory content validity (CVI = 0.98, CVR = 0.96), good reliability (Cronbach's α coefficient = 0.84) and acceptable construct validity (χ2/df = 2.28, GFI = 2.81, AGFI = 0.79, RMSEA = 0.057). In the application part, the average NL score was 46.0 ± 9.3. In multivariate linear regression, education level, age, postnatal period and occupation were the potential influencing factors of NL for Chinese lactating women. The study established an effective and reliable assessment instrument for Chinese lactating women (NLAI-L) through qualitative and quantitative methods. The establishment of NLAI-L will provide an effective tool for exploring the role of NL in health or disease and provide a basis for the formulation of targeted nutrition interventions.

Single-molecule visualization determines conformational substate ensembles in ß-sheet-rich peptide fibrils.

An understanding of protein conformational ensembles is essential for revealing the underlying mechanisms of interpeptide recognition and association. However, experimentally resolving multiple simultaneously existing conformational substates remains challenging. Here, we report the use of scanning tunneling microscopy (STM) to analyze the conformational substate ensembles of ß sheet peptides with a submolecular resolution (in-plane <2.6 Å). We observed ensembles of more than 10 conformational substates (with free energy fluctuations between several kBTs) in peptide homoassemblies of keratin (KRT) and amyloidal peptides (-5Aß42 and TDP-43 341-357). Furthermore, STM reveals a change in the conformational ensemble of peptide mutants, which is correlated with the macroscopic properties of peptide assemblies. Our results demonstrate that the STM-based single-molecule imaging can capture a thorough picture of the conformational substates with which to build an energetic landscape of interconformational interactions and can rapidly screen conformational ensembles, which can complement conventional characterization techniques.

Experimental Insights into Conformational Ensembles of Assembled ß-Sheet Peptides.

Deciphering the conformations and interactions of peptides in their assemblies offers a basis for guiding the rational design of peptide-assembled materials. Here we report the use of scanning tunneling microscopy (STM), a single-molecule imaging method with a submolecular resolution, to distinguish 18 types of coexisting conformational substates of the ß-strand of the 8-37 segment of human islet amyloid polypeptide (hIAPP 8-37). We analyzed the pairwise peptide-peptide interactions in the hIAPP 8-37 assembly and found 82 interconformation interactions within a free energy difference of 3.40 kBT. Besides hIAPP 8-37, this STM method validates the existence of multiple conformations of other ß-sheet peptide assemblies, including mutated hIAPP 8-37 and amyloid-ß 42. Overall, the results reported in this work provide single-molecule experimental insights into the conformational ensemble and interpeptide interactions in the ß-sheet peptide assembly.

ß-Sheet Assembly Translates Conservative Single-Site Mutation into a Perturbation in Macroscopic Structure.

Transferring structural information from amino acid sequence to macroscale assembly is a challenging approach for designing protein quaternary structure. However, the pathway by which the slight variations in sequence result in a global perturbation effect on the assembled structure is unknown. Herein, we design two synthetic peptides, QNL-His and QNL-Arg, with one amino acid substitution and use scanning tunneling microscopy (STM) to image individual peptides in the assembled state. The submolecular resolution of STM enables us to determine the folding structure and ß-sheet supramolecular organization of peptides. QNL-His and QNL-Arg differ in their ß-strand length distribution in pleated ß-sheet association. These structural variations lead to distinguishable outcomes in their ß-sheet assembled fibrils and phase transitions. The comparison of QNL-His versus QNL-Arg structures and macroscopic properties unveils the role of assembly to amplify the structural variations associated with a single-site mutation from a single-molecule scale to a macroscopic scale.

Determination of neotame in various foods by high-performance liquid chromatography coupled with ultraviolet and mass spectrometric detection.

A new analytical technique involving protein precipitation, heating, lipid degreasing, and SPE procedures combined with HPLC-UV and HPLC-MS/MS has been developed for the determination of neotame in a variety of food samples. This method is applicable for high-protein, high-lipid, or gum-based solid samples. The limit of detection of the HPLC-UV method was 0.5 µg/mL, while that of the HPLC-MS/MS method was 3.3 ng/mL. The spiked recoveries of neotame in 73 kinds of foods were in the range of 81.1-107.2 % with UV detection. The spiked recoveries obtained by HPLC-MS/MS in 14 kinds of foods ranged from 81.6 % to 105.8 %. This technique was successfully used to determine the contents of neotame in two positive samples, indicating its applicability in food analysis.