Research on Dynamic Modeling Method and Flying Gait Characteristics of Quadruped Robots with Flexible Spines.

In recent years, both domestic and international research on quadruped robots has advanced towards high dynamics and agility, with a focus on high-speed locomotion as a representative motion in high-dynamic activities. Quadruped animals like cheetahs exhibit high-speed running capabilities, attributed to the indispensable role played by their flexible spines during the flight phase motion. This paper establishes dynamic models of flexible spinal quadruped robots with different degrees of simplification, providing a parameterized description of the flight phase motion for both rigid-trunk and flexible-spine quadruped robots. By setting different initial values for the spine joint and calculating the flight phase results for both types of robots at various initial velocities, the study compares and analyzes the impact of a flexible spine on the flight phase motion of quadruped robots. Through comparative experiments, the research aims to validate the influence of a flexible spine during the flight phase motion, providing insights into how spine flexibility affects the flight phase motion of quadruped robots.

Study the key biogenic amines in luncheon meat by capillary electrophoresis with indirect ultraviolet detection.

In this work, a simple, accurate, and rapid capillary electrophoresis with an indirect ultraviolet detection method was developed to simultaneous separate 10 biogenic amines. It was found that ß-cyclodextrin and ethylene diamine tetraacetic acid facilitated the separation of tryptamine and tyramine, spermidine and spermine, respectively. The optimized background electrolytes consisted of 20.0 mmol/L imidazole, 8.0 mmol/L ß-cyclodextrin, 0.5 mmol/L ethylene diamine tetraacetic acid, and 6.0% methanol (at pH 4.50 adjusted with acetic acid). The total analysis time of this method was less than 11 min with limits of detection in the range of 0.14-1.98 mg/L. The interday relative standard deviation of migration time and peak area were less than 1.36% and 4.44% (n = 6), respectively. To verify the applicability, this method was carried out to analyze biogenic amines in commercial luncheon meat samples. Due to the complex composition of luncheon meat, the real samples were rinsed with deionized water to reduce the influence of matrices. It was found that both storage temperature and protein content of the luncheon meat samples affected the biogenic amines content during storage. The results of this study are instructive for the storage of high-protein meat products.

Pressure-assisted electrokinetic injection for the stacking of biogenic amines gives enhancement factor up to 1000 in CE with UV detection.

Pressure-assisted electrokinetic injection (PAEKI) was applied for stacking of positively charged biogenic amines (BAs) to improve the sensitivity of capillary electrophoresis (CE). It is well known that the essential step for PAEKI is finding a stationary state of the running buffer such that the movement of the running buffer due to electroosmotic flow (EOF) is counterbalanced by external pressure in the opposite direction of the EOF under a given electric field. In order to find the balance point systematically and integrally, we studied the velocity of the whole BGE in the capillary by the impetus of opposite direction pressure (-0.1 to -0.6 psi), and the velocity of EOF with different voltages. According to the two sets of linear data, the EOF of CE coupled with PAEKI could be counterbalanced at the opposite direction pressure (-0.1 psi) and voltage (7.8 kV). In this study, the injection time was extended up to 0.35 min for all BAs and 0.70 min for the direct ultraviolet (UV) detection of BAs. Compared with hydrodynamic injection (HDI), the enrichment factors for sample injection times of 0.35 min and 0.70 min were 480-fold and 970-fold, respectively. The limits of detection (LODs) (S/N = 3) of indirect and direct UV detection were respectively 8.7-24.3 nmol L-1 and 0.4-4.5 nmol L-1, which reaches the sensitivity of high-performance liquid chromatography-mass spectrophotometry (HPLC-MS). With appropriate sample dilution, PAEKI can be used in the analysis of BAs in chicken.

Simultaneous separation of 12 different classes of antibiotics under the condition of complete protonation by capillary electrophoresis-coupled contactless conductivity detection.

A novel capillary electrophoresis - capacitively coupled contactless conductivity detection (CE-C4D) method for the separation of 12 antibiotics, including four types of aminoglycosides, three types of fluoroquinolones, two types of tetracyclines, and three types of macrolides, was developed. Half of these antibiotics were not determined by ultraviolet (UV) because of their lack of UV-absorbing groups. Formic acid (FA) (pH 2.50) with low conductivity was employed as the background electrolyte (BGE) in comparison with three BGE systems (i.e., HAc, HCl and H3PO4), which not only allowed complete protonation and electrophoresis separation but provided more cost-effectiveness and shorter analysis time. Under these conditions, a UV detector was employed as an additional detection mode to evaluate the qualitative analysis of 6 antibiotics possessing UV absorbing groups. Moreover, it was found that the sensitivities of the C4D and UV detectors were similar. Albeit a slightly reduced sensitivity of C4D in the analysis of norfloxacin, enrofloxacin and tylosin compared to UV, enough points were achieved to detect all analytes by C4D. The repeatability with respect to peak areas and migration times was better than 4.69% and 2.48% (n = 5), respectively. Mixed liquid pharmaceutical formulations of tobramycin eye drops having non-UV absorbing groups and ofloxacin eye drops possessing UV absorbing groups have been separated and detected in a single run by this technique. The studied recoveries of the two were 100% and 103%, respectively.

Influence of Beijing Winter Olympic Games Construction on Vegetation Coverage around Zhangjiakou Competition Zone.

There is a rising concern that Olympic venue construction may affect the surrounding environment. The construction of Winter Olympic venues and competition zones is more likely to degrade the surrounding natural environment than the summer counterpart, considering the prominent land use change and extensive vegetation disturbance during the construction of ski trails in mountainous areas. Scientific assessment of the impact of this Winter Olympic Games construction on the surrounding ecological environment can be of significance for the construction of a Green Olympics. At this stage, the main framework of venue and competition construction in Zhangjiakou for the Beijing Winter Olympic Games is essentially completed, so we assessed the vegetation coverage change conditions based on the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) from 2000 to 2020. Our results show that the construction of venues, roads, and other facilities for the 2022 Olympic Games led to a remarkable change in land use, but the impacts on vegetation coverage were negligible in the surrounding area. Due to the intensive reforestation activities since the year that Beijing won the race to host the Winter Olympics, vegetation coverage continued to increase in the Zhangjiakou area, even in the core area of Winter Olympic Games construction zones. This study provides support to the belief in hosting a Green Olympics.

Capillary electrophoresis with dual C4D/UV detection for simultaneously determining major metal cations and whey proteins in milk.

A reliable and simple CE method with dual C4D and UV detection modes for simultaneous determination of major metal cations and whey proteins in milk samples was developed. Sample pretreatment comprised dilution, acidification to pH 4.55 with 10 mM AcOH and centrifugation. The complete separation of metal cations K+, Ca2+, Na+, and Mg2+ and whey proteins α-Lac, and ß-Lg could be achieved respectively within 10 min and 20 min in a simple BGE composed of 1.0 M AcOH, 12 mM l-His and 2 mM 18-crown-6 with pH 2.74 at a voltage/current of +15 kV/12.5 µA. The samples were injected hydrodynamically by a pressure of 50 mbar for 5 s, the excitation voltage and excitation frequency of the C4D detector were 80 V and 1000 kHz, respectively and the detection wavelength of UV detection was set at 200 nm. In cation analysis, the range of the detection limit was 0.05-0.10 mg L-1 for C4D detection and 0.10-0.50 mg L-1 for UV detection, respectively, and the relative standard deviations (RSD%, n = 5) of intraday and interday analysis were 0.37-0.55% and 0.46-0.79% for the relative migration time, and 2.51-4.12% and 3.65-4.91% for the peak area, respectively. In whey protein analysis, the detection limits of ß-Lg and α-Lac analysis were 5 mg L-1 and 3 mg L-1, respectively and the relative standard deviations (RSD%, n = 5) of intraday and interday analysis were 0.29-0.31% and 0.43-0.48% for the migration time and 2.89-3.25% and 3.29-4.18% for the peak area, respectively. The content of four major metal cations and two whey proteins in various types of milk samples was obtained. The results indicated that the content of metal cations varied little in milk samples of different brands and prices, while the content of whey proteins, as thermosensitive active proteins, varied greatly among different heat-treated milk samples.

Investigation on the chiral recognition mechanism between verteporfin and cholate salts by capillary electrophoresis.

In this article, capillary electrophoresis was applied to investigate the chiral recognition mechanism for the enantioseparation on a well-known second-generation photodynamic therapy drug of benzoporphyrin derivative monoacid ring A, that is, verteporfin. In our previous study, cholate salts have been studied as the chiral selectors, which can realize baseline separation of the four verteporfin isomers. Aiming to reveal the chiral recognition mechanism, the separation effect of several kinds of chiral selectors was discussed. According to the results and references, the chiral separation mechanism of this system was concluded: the analytes selectively combine with the chiral micelles, that is, dynamic H-bonds interactions occur between the hydroxyl groups on the outer side of the cholate micelles and the ester/carboxy groups of the four isomers. In addition, the role of dimethyl formamide as an organic modifier was also researched, including reducing the effective mobility of the analytes and mobility of electroosmotic flow, and preventing them from adsorbing to the capillary wall and self-aggregating of verteporfin, which are pretty beneficial for separation. The method used in this article provides a direct and reliable solution to study the mechanism of chiral separation.

Spinal intraosseous schwannoma without spinal canal and neuroforamina involvement: A case report.

BACKGROUND: Spinal intraosseous schwannomas (SIS) are rare, and as yet have not been fully described in the literature. The first case of SIS was reported in 1971, and 24 cases of SIS have been reported so far. However, including the present case, there are only seven cases without spinal canal and neuroforamina involvement. CASE SUMMARY: A 56-year-old man presented with a history of neck pain for 2 years. An obvious osteolytic destruction of the seventh cervical (C7) vertebra was observed on imaging examination. Magnetic resonance imaging of the cervical spine showed space-occupying lesions in the C7 vertebra, and destruction of the anterior cortex of the vertebra. The lesions had an exophytic component that extended from the C7 vertebra into the soft tissue on the front side. The foramen transversarium on both sides were intact. The patient underwent surgical biopsy and focal excision of the C7 lesion. The diagnosis of "schwannoma" was verified by postoperative pathological examinations. In a review of the literature, this is the seventh case of SIS without spinal canal and neuroforamina involvement, and the third reported case of type VIII SIS. We discussed our case with respect to reported classification characteristics of SIS. CONCLUSION: SIS is a very rare tumor. We report a rare case that may be important for further classification of osteo-schwannoma. The establishment of a complete disease classification is of high importance for the treatment and prognosis of this disease. Thus, more basic studies and retrospective analysis of related cases are necessary.

LncRNA CASC11 is upregulated in postmenopausal osteoporosis and is correlated with TNF-α.

PURPOSE: In this study, we aimed to investigate the role of lncRNA cancer susceptibility 11 (CASC11) and tumor necrosis factor (TNF-α) in postmenopausal osteoporosis (POP). METHODS AND MATERIALS: POP patients and healthy controls were included in this study and levels of CASC11 and TNF-α in plasma of those participants were measured by qPCR and Western blot, respectively. ROC curve was used for diagnostic analysis. Patients were followed up for 2 years and the correlations between the levels of CASC11 and TNF-α and disease conditions were analyzed. RESULTS: We found that CASC11 and TNF-α were both upregulated in plasma of POP patients than in healthy controls. Plasma levels of CASC11 and TNF-α were positively correlated in both POP patients and in healthy controls. Upregulation of CASC11 and TNF-α distinguished POP patients from healthy controls. Treatment and follow-up study showed that high CASC11 levels were significantly correlated with prolonged treatment course and high recurrence rate. Plasma levels of CASC11 and TNF-α decreased after treatment. CASC11 overexpression led to upregulated TNF-α in osteoclasts. CONCLUSION: CASC11 is upregulated in POP and is correlated with TNF-α.

Iodine-mediated aminosulfonylation of alkenyl sulfonamides with sulfonyl hydrazides: synthesis of sulfonylmethyl piperidines, pyrrolidines and pyrazolines.

An aminosulfonylation of alkenyl sulfonamides was reported. Using iodine as the catalyst, TBHP as the oxidant, and sulfonyl hydrazides as the sulfonyl radical sources, a variety of sulfonylmethyl piperidines, pyrrolidines and pyrazolines were obtained in moderate to excellent yields.

An ultrahigh resolution pressure sensor based on percolative metal nanoparticle arrays.

Tunneling conductance among nanoparticle arrays is extremely sensitive to the spacing of nanoparticles and might be applied to fabricate ultra-sensitive sensors. Such sensors are of paramount significance for various application, such as automotive systems and consumer electronics. Here, we represent a sensitive pressure sensor which is composed of a piezoresistive strain transducer fabricated from closely spaced nanoparticle films deposited on a flexible membrane. Benefited from this unique quantum transport mechanism, the thermal noise of the sensor decreases significantly, providing the opportunity for our devices to serve as high-performance pressure sensors with an ultrahigh resolution as fine as about 0.5 Pa and a high sensitivity of 0.13 kPa-1. Moreover, our sensor with such an unprecedented response capability can be operated as a barometric altimeter with an altitude resolution of about 1 m. The outstanding behaviors of our devices make nanoparticle arrays for use as actuation materials for pressure measurement.

Metal-free oxysulfonylation and aminosulfonylation of alkenyl oximes: synthesis of sulfonylated isoxazolines and cyclic nitrones.

Intramolecular oxysulfonylation of alkenyl oximes was reported. Using iodine as the catalyst, TBHP as the oxidant, and sulfonyl hydrazides as the sulfonyl radical source, a variety of sulfonylated isoxazolines were obtained in moderate to excellent yields. Cyclic nitrones could also be readily obtained under the same conditions.

Construction of 3,4-Dihydroisoquinolinones and Indanones via DTBP-Promoted Oxidative Coupling of N-Allylbenzamides with Aromatic Aldehydes.

A metal-free oxidative tandem coupling of N-allylbenzamide with aryl aldehydes was realized. This method allowed the 1,2-difunctionalization of the C═C double bond in N-allylbenzamides through simultaneous formation of two C(sp2)-C(sp3) bonds. In the presence of DTBP, 4-substituted 3,4-dihydroisoquinolin-1(2 H)-ones were obtained in satisfactory isolated yields. 3-Substituted indanones could also be formed by varying the structures of the starting materials.

Study of isomeric pentacyclic triterpene acids in traditional Chinese medicine of Forsythiae Fructus and their binding constants with ß-cyclodextrin by capillary electrophoresis.

In this study, a capillary zone electrophoresis (CZE) method was first developed to identify three microconstituents of isomeric pentacyclic triterpene acids (PTAs including oleanolic acid (OA), ursolic acid (UA) and betulinic acid (BA)) in Forsythiae Fructus (FF). The baseline separation of PTAs by CZE were eventually achieved in a background electrolyte (BGE) containing 50.0 mmol/L borax and 0.5 mmol/L ß-cyclodextrin (ß-CD) at pH 9.5 within 13.0 min. Herein, it was not only the compositions of BGE were detail investigated for rapid and good separation, but also the binding ratio and the equilibrium constants (K) for OA, UA and BA with ß-CD was estimated by double reciprocal equation to well understand the separation mechanism. The proposed method allowed the LODs of PTAs were averaged at 1.50 µg/mL with UV detection (at 200 nm). The interday RSD of migration time and peak area were around 2.0 and 4.7% (n = 5), respectively. Thus, the content of PTAs in 19 FF real samples distinguished from maturation stages and geographical areas in China was quantified with the proposed method. Depending on the amount of each PTA in FF, it was demonstrated these microconstituents might benefit to identify their harvested time even qualities.

Quantitation of underivatized branched-chain amino acids in sport nutritional supplements by capillary electrophoresis with direct or indirect UV absorbance detection.

The branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) play a pivotal role in the human body. Herein, we developed capillary electrophoresis (CE) coupled with conventional UV detector to quantify underivatized BCAAs in two kinds of sport nutritional supplements. For direct UV detection at 195 nm, the BCAAs (Leu, two enantiomers of Ile and Val) were separated in a background electrolyte (BGE) consisting of 40.0 mmol/L sodium tetraborate, and 40.0 mmol/L ß-cyclodextrin (ß-CD) at pH 10.2. In addition, the indirect UV detection at 264 nm was achieved in a BGE of 2.0 mmol/L Na2HPO4, 10.0 mmol/L p-aminosalicylic acid (PAS) as UV absorbing probe, and 40.0 mmol/L ß-CD at pH 12.2. The ß-CD significantly benefited the isomeric separation of Leu, L- and D-Ile. The optimal conditions allowed the LODs (limit of detections) of direct and indirect UV absorption detection to be tens µmol/L level, which was comparable to the reported CE inline derivatization method. The RSDs (relative standard deviations) of migration time and peak area were less than 0.91% and 3.66% (n = 6). Finally, CE with indirect UV detection method was applied for the quantitation of BCAAs in two commercial sport nutritional supplements, and good recovery and precision were obtained. Such simple CE method without tedious derivatization process is feasible of quality control and efficacy evaluation of the supplemental proteins.

Microwave ablation for the treatment of hepatocellular carcinoma that met up-to-seven criteria: feasibility, local efficacy and long-term outcomes.

OBJECTIVES: This study aimed to evaluate the feasibility, local efficacy and long-term outcomes of microwave (MW) ablation for the treatment of hepatocellular carcinoma (HCC) that met up-to-seven criteria. METHODS: Between January 2007 and January 2012, 142 HCC patients with 294 nodules, which conformed to up-to-seven criteria, were enrolled into this retrospective study. All patients were followed up for more than 3 years after receiving MW ablation. Technical success, complications, local tumour progression (LTP) and distant recurrence (DR) were monitored. Recurrence-free survival (RFS), overall survival (OS) and prognostic factors were analysed. RESULTS: Primary technical efficacy was achieved in 95.2% (280/294) of the carcinomatous nodules, and major complications occurred in four (2.8%) patients. Among the 294 tumours, LTP was observed in 44 (15.0%) tumours. Among the 142 patients, DR was observed in 97 (68.3%) patients. The estimated OS rates after MW ablation at 1, 3 and 5 years were 97.2%, 75.4% and 50.6%, respectively; and the corresponding RFS rates were 76.1%, 33.1% and 19.5%, respectively. CONCLUSIONS: MW ablation is a safe and effective treatment with a high rate of primary technical efficacy for patients with HCC that met up-to-seven criteria. KEY POINTS: • The first study expanding MW ablation to HCC category beyond Milan criteria. • The first report that used up-to-seven criteria as indications for MW ablation. • HCC of up-to-seven criteria viewed as a subgroup of BCLC stage B. • MW ablation is safe and effective for treating HCC within up-to-seven criteria. • MW ablation is preferable in treating unresectable HCC within up-to-seven criteria.

Neuroprotective effect and mechanism of daucosterol palmitate in ameliorating learning and memory impairment in a rat model of Alzheimer's disease.

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by progressive memory decline and cognitive impairment. Amyloid beta (Aß) has been proposed as the causative role for the pathogenesis of AD. Accumulating evidence demonstrates that Aß neurotoxicity is mediated by glutamate excitotoxicity. Daucosterol palmitate (DSP), a plant steroid with anti-glutamate excitotoxicity effect, was isolated from the anti-aging traditional Chinese medicinal herb Alpinia oxyphylla Miq. in our previous study. Based on the anti-glutamate excitotoxicity effect of DSP, in this study we investigated potential benefit and mechanism of DSP in ameliorating learning and memory impairment in AD model rats. Results from this study showed that DSP administration effectively ameliorated Aß-induced learning and memory impairment in rats, markedly inhibited Aß-induced hippocampal ROS production, effectively prevented Aß-induced hippocampal neuronal damage and significantly restored hippocampal synaptophysin expression level. This study suggests that DSP may be a potential candidate for development as a therapeutic agent for AD cognitive decline.

Simultaneous determination of aliphatic, aromatic and heterocyclic biogenic amines without derivatization by capillary electrophoresis and application in beer analysis.

Biogenic amines (BAs) play significant roles in indicating human health or food quality. Aiming to simultaneously determine three structures (aliphatic, aromatic and heterocyclic) of underivatized BAs, we explored a simple and rapid capillary electrophoresis (CE) method only coupled with conventional UV detector for the separation of thirteen key BAs. The strategy is to choose a UV absorbing probe as co-ion in the background electrolyte (BGE), and different BAs could be characterized by positive or negative peaks according to the fact that their UV absorptivity coefficients at a certain wavelength are better or worse than that of the UV absorbing probe. After the detailed investigation of critical parameters as pH, the concentration of Imidazole (Im) and α-cyclodextrin (α-CD), the optimized BGE consisted of 12.0mmol/L Im as the UV probe and 10.0mmol/L α-CD as the additive (at pH 4.50 adjusted with acetic acid). With such condition, the targets of thirteen BAs were baseline separated in 9.0min and appeared at nine positive peaks and four negative peaks at 200nm. The obtained LODs and LOQs (S/N=3 or 10) were in the range of 0.36-3.67 and 1.2-12.2µmol/L, respectively. The interday RSDs of migration time and peak area were less than 0.7% and 4.7% (n=6), respectively. To the best of our knowledge, this is the first report on separating diverse structures of BAs by using Im as UV absorbing probe. The thirteen BAs were simultaneously detected by direct and indirect UV detection in a CE process. To verify the applicability, this method was used to analyze BAs in commercial beer samples. The recoveries of all BAs except carnosine (not identified by the interference) ranged from 70.4 to 119.6%, and four aliphatic and aromatic amines were satisfactorily identified and quantified.

Large volume sample stacking of cationic tetracycline antibiotics toward 10 ppb level analysis by capillary electrophoresis with UV detection.

This paper aimed to build up a sensitive CE method for the analysis of tetracyclines (TCs) antibiotics (including tetracycline, chlorotetracycline, oxytetracycline, and doxycycline) with conventional UV detection. Here, the large volume sample stacking was applied to achieve in capillary preconcentration of the targets. To achieve large volume sample stacking, the essential step was a large volume of sample (around 83.3% of total capillary length from inlet to detection window) hydrodynamically loaded. Then, the reserved voltage was added in order to push the sample matrix out of the capillary. Due to different pH between sample solution (pH 4.6) and BGE (pH 11.0), the cationic TCs would turn into negatively charged while the sample matrix was removing from the capillary. Finally, the anionic TCs were stacked at the inlet for the subsequent separation. Although the loss of sample existed during their charge transformation, the LODs could be improved around 40 times than that obtained by normal hydrodynamic injection CE method. Here, the LODs were in the range of 8.1-14.5 µg/L, around 10 ppb that close to the level by electrochemiluminescence or laser-induced fluorescence detection of TCs by CE. The precision was characterized by RSDs of migration times and peak areas, which were in the range of 0.19-0.24% and 0.97-2.54%, respectively. The recoveries of the developed method were in the range of 95-112% by spiking TCs in the tap water. The proposed inline preconcentration CE method could be a simple, speed, and sensitive method for the quantitative analysis of TCs.

Separation of Key Biogenic Amines by Capillary Electrophoresis and Determination of Possible Indicators of Sport Fatigue in Athlete's Urine.

This article aims to build up a simple, rapid and accurate capillary zone electrophoresis (CZE) method for the separation of biogenic amines (BAs). Here, 10 key BAs (phenethylamine, histamine, tryptamine, tyramine, 5-hydroxytryptamine, octopamine, dopamine, norepinephrine, epinephrine and carnosine) owning significant functions were chosen for method development. The baseline separation and identification of 10 standards of the mixture by CZE were eventually achieved in 150.0 mmol/L phosphate buffer (Na2HPO4-NaH2PO4) containing 1.0 mmol/L borax at a pH of 6.1. The addition of borax was found effective for improving the isomeric separation of octopamine and dopamine. The proposed method allowed the limits of detections of BAs to be in the range of 0.2-1.2 µmol/L at UV detection (200 nm); the relative standard deviation of the migration time and the peak area were in the ranges 0.08-0.12 and 2.74-4.63% (n = 5), respectively. Formaldehyde (a possible antiseptic in urine) and five main matrices in urine were studied for the identification of BAs. Finally, profiling of BAs in actual urine from athletes was carried out. Currently, only phenethylamine, norepinephrine and carnosine were designated by spiking the standards. In addition, their variation in athletes' urine has been checked at different states of sport fatigue with the goal of obtaining possible indicators of sport fatigue.