bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid and adjustable shifted excitation Raman difference spectroscopy using a dual‐wavelength diode laser at 785 nm
Authors: Maiwald Martin , Sumpf Bernd , Tränkle Günther 
Published: July 2018

AbstractIn this paper, we present rapid and adjustable shifted excitation Raman difference spectroscopy (SERDS). A dual‐wavelength diode laser emitting at 785 nm is used as the excitation light source. Two laser resonators are realized in a single chip, and two distributed Bragg reflector gratings provide two excitation lines at 785 nm. For each laser line, an optical power of 170 mW is achieved. Two separate heater elements are implemented and are used to realize a flexible spectral distance up to 36 cm−1. At selected spectral distances from 1 to 30 cm−1, an alternating operation with modulation frequencies up to 100 Hz is performed and shows stable spectral properties including a narrow linewidth of 11 pm. Raman experiments are carried out using ethanol as the target substance and Irish cream as the test sample. Raman and SERDS spectra at the selected spectral distances are presented and discussed with respect to the analytes under study. The described alternating operation for SERDS is demonstrated with integration times down to 50 ms for a single Raman spectrum. A carefully selected spectral distance of 15 cm−1 between both laser lines allows a discrimination of closely neighbored Raman bands of Irish cream and shows a 15‐fold improvement of the signal‐to‐background noise in the reconstructed SERDS spectra. The results demonstrate rapid and adjustable SERDS using a dual‐wavelength diode laser as a potential tool for Raman applications such as real‐time diagnostic during surgeries, in situ measurements, which require quick on‐site decisions, and Raman experiments with strong background interferences, for example, from laser‐induced fluorescence and ambient light.
Determination of aflatoxin M1 and B1 in milk and jujube by miniaturized solid‐phase extraction coupled with ultra high performance liquid chromatography and quadrupole time‐of‐flight tandem mass spectrometry
Authors: Du Lijing , Wang Shuling , Huang Jianping , Chu Chu , Li Rongrong , Li Qin , Wang Qiuyan , Hu Yuhan , Cao Jun , Chen Yubo , Peng Liqing , Yang Juan 
Published: July 2018

AbstractA miniaturized solid‐phase method was proposed for the extraction of aflatoxin M1 and B1 from milk and jujube samples. Target analytes were identified by ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight tandem mass spectrometry in positive mode. The main factors that affected the extraction ability and sensitivity of the analytical method were evaluated in detail. In the optimal conditions, 30 mg of silica particles functionalized with octadecyltrimethoxysilane and methanol were used as sorbent and desorption solvent in miniaturized solid‐phase extraction, respectively. The calibration curves for aflatoxin B1 and M1 showed good linearity (r2 > 0.9921) within linear ranges. The limit of detection (S/N = 3) were determined to be 0.049 and 0.023 μg/kg for aflatoxin M1 and B1, respectively. In addition, the good spiked recoveries were obtained ranging from 88.24 to 105.35%. The results demonstrated that the proposed method had significant advantages including simple, inexpensive, rapid, and accurate, which considered as a suitable method for the trace analysis of aflatoxins.
Separation of six compounds including two n‐butyrophenone isomers and two stibene isomers from Rheum tanguticum Maxim by recycling high speed counter‐current chromatography and preparative high‐performance liquid chromatography
Authors: Chen Tao , Yang Xue , Wang Nana , Li Hongmei , Zhao Jingyang , Li Yulin 
Published: July 2018

AbstractSix compounds including two n‐butyrophenone isomers and two stibene isomers were obtained from Rheum tanguticum Maxim. Two n‐butyrophenone isomers with a separation factor of 1.14 were successfully separated by recycling high‐speed counter‐current chromatography after ten cycles. Two stibene isomers were successfully separated by preparative high‐performance liquid chromatography. High‐performance liquid chromatography analysis showed that the purities of the compounds were all over 98%. These compounds were identified as lindleyin, isolindleyin, resveratrol‐4′‐O‐(2″‐O‐galloyl)‐glucopyranoside, resveratrol‐4′‐O‐(6′′‐O‐galloyl)‐glucopyranoside, emodin 1‐O‐β‐d‐glucoside, and 3,5‐dihydroxy‐4′‐methoxystilbene‐3‐O‐β‐d‐glucopyranoside. The results indicated that recycling high‐speed counter‐current chromatography and preparative high‐performance liquid chromatography could be effective combination for the preparation of bioactive compounds from Rheum tanguticum Maxim.
Simultaneous qualitative and quantitative analysis of 11 active compounds in rhubarb using two reference substances by UHPLC
Authors: Chen Anzhen , Sun Lei , Yuan Hang , Wu Aiying , Lu Jingguang , Ma Shuangcheng 
Published: July 2018

AbstractMulti‐component analysis is one of the key techniques for the overall quality control of traditional Chinese medicines. However, the shortage and high cost of reference substances are the greatest obstacles. The substitute method is an alternative solution. In the present study, 11 compounds of rhubarb were simultaneously determined by a method named “two reference substances for determination of multiple components”, which includes a qualitative method with linear calibration using two reference substances and a quantitative method with a relative correction factor combined with ultra high performance liquid chromatography. Using aloe‐emodin‐8‐O‐β‐D‐glucopyranoside and chrysophanol as reference compounds, chromatographic peak identification was performed. The results demonstrated that linear calibration using two reference substances method showed higher accuracy, less deviation, and better column adaptability compared to the relative retention time method. Using chrysophanol as a reference compound, the relative correction factors were determined and showed good reproducibility and stability in different laboratories with different instruments, columns, and wavelength fluctuations. The results had no significant difference compared with the external standard method. The strategy of two reference substances for determination of multiple components coupled with ultra high performance liquid chromatography is economical, efficient, accurate, reliable, and environmentally friendly and is suitable for the quality control of traditional Chinese medicines.
Influence of consecutive integrated rice–crayfish culture on phosphorus fertility of paddy soils
Authors: Li Qingman , Xu Lei , Xu Lijing , Qian Yiguang , Jiao Yang , Bi Yonghong , Zhang Tanglin , Zhang Wen , Liu Yanjie 
Published: July 2018

AbstractChina has experienced an increase in integrated rice–crayfish (Procambarus clarkii) culture (IRCC) in rice paddies. However, whether the current regime degrades phosphorus (P) fertility in rice paddies remains unclear. To assess changes in P fertility, the surface soil (0–20 cm) of high‐yield rice paddies with 3, 6, and 10 consecutive years of IRCC was sampled in Honghu County in the Jianghan Plain region, China. Adjacent fields planted with long‐term rotations of rice and dry‐season crops (RRD) were also sampled. Total P (TP), available P (Pa), organic P (Po) compounds, and P fractions in soils were intensively assessed using chemical digestion, NaHCO3 extraction, 31P nuclear magnetic resonance, and sequential chemical extraction. IRCC significantly increased organic matter, total nitrogen, TP, Fe(II), and S2− contents of rice paddy soils and nutrient concentrations in the surface water, with a distinct decrease in total Fe and pH. Consecutive IRCC greatly influenced P fertility. Continuous P accumulation in rice paddy soils accelerated greatly, with a mean increase of approximately 43 mg·kg−1·yr−1. Pa was 67% higher after 3 years of IRCC, compared with RRD, but 78% lower after 10 years. Consecutive IRCC induced a decrease in Po compounds, with a mean decrease in TPo of approximately 20 mg·kg−1·yr−1. Long‐term consecutive IRCC increased transformation of Pa, Fe(II)–P, and Po into Ca–P and Fe(III)–P, increasing mean Ca–P and Fe(III)–P concentrations by approximately 69 and 7 mg·kg−1·yr−1, respectively. Our results suggested that long‐term consecutive IRCC degrades P fertility in rice paddies, and implementing IRCC in high‐yield rice paddies is not recommended.
Hyperbranched Polymers Formed Through Self‐Condensing Vinyl Polymerization in a Continuous Stirred‐Tank Reactor (CSTR): 2. Branched Architecture
Authors: Tobita Hidetaka 
Published: July 2018

AbstractThe Monte Carlo simulation method proposed in Part 1 of this series is used to investigate the branched architecture of hyperbranched polymers formed through self‐condensing vinyl polymerization (SCVP) in a continuous stirred‐tank reactor (CSTR). The degree of branching (DB) at large chain length (P) limit, DBinf, does not change with the mean residence time . The value of DBinf is larger than the corresponding batch polymerization. The relationship between the mean‐square radius of gyration <s2>0 and P does not change with , and high molecular weight (MW) polymers obtained in a CSTR are much more compact than those formed in batch polymerization. At least for the high MW polymers, CSTR is advantageous to synthesize compact hyperbranched polymers.
Antimicrobial efficacy of alternative compounds for use in oral care toward biofilms from caries‐associated bacteria in vitro
Authors: Cieplik Fabian , Kara Esra , Muehler Denise , Enax Joachim , Hiller Karl‐Anton , Maisch Tim , Buchalla Wolfgang 
Published: July 2018

AbstractFor caries‐active patients, antimicrobial measures may be useful in addition to mechanical biofilm removal. The aim of this study was to investigate the antimicrobial efficacy of alternative compounds for use in oral care from two main categories (i.e., preservatives and natural compounds) toward biofilms from caries‐associated bacteria as compared to oral care gold‐standards chlorhexidine digluconate (CHX), cetylpyridinium chloride (CPC), and zinc. Compounds were screened in initial Streptococcus mutans biofilms. Then, the most effective compounds were further investigated in mature S. mutans and polymicrobial biofilms comprising Actinomyces naeslundii, Actinomyces odontolyticus, and S. mutans. Here, distinct treatment periods and concentrations were evaluated. Biofilms were visualized by scanning electron microscopy and bacterial membrane damage was evaluated by means of flow cytometry and staining with SYBR Green and propidium iodide. Citrus extract was the only compound exhibiting similar antimicrobial efficacy in initial S. mutans biofilms (>5 log10) as compared to CHX and CPC, but its effect was clearly inferior in mature S. mutans and polymicrobial biofilms. Flow cytometric data suggested that the mechanism of antimicrobial action of citrus extract may be based on damage of bacterial membranes similar to CHX and CPC. From all alternative compounds investigated in this study, citrus extract exhibited the highest antimicrobial efficacy toward in vitro biofilms from caries‐associated bacteria, but still was less effective than oral care gold‐standard antiseptics CHX and CPC. Nevertheless, citrus extract may be a valuable antimicrobial compound for use in oral care for caries‐active patients.
Flap‐site Fragment Restores Back Wild‐type Behaviour in Resistant Form of HIV Protease
Authors: Luchi Adriano , Angelina Emilio , Bogado Lucrecia , Forli Stefano , Olson Arthur , Peruchena Nélida 
Published: July 2018

AbstractHIV‐1 protease (HIV‐PR) performs a vital step in the virus life cycle which makes it an excellent target for drug therapy. However, due to the error‐prone of HIV reverse transcriptase, mutations in HIV‐PR often occur, inducing drug‐resistance to inhibitors. Some HIV‐PR mutations can make the flaps of the enzyme more flexible thus increasing the flaps opening rate and inhibitor releasing. It has been shown that by targeting novel binding sites on HIV‐PR with small molecules, it is possible to alter the equilibrium of flap conformational states. A previous fragment‐based crystallographic screen have found two novel binding sites for small fragments in the inhibited, closed form of HIV‐PR, termed flap and exo sites. While these experiments were performed in wild type HIV‐PR, it still remains to be proven whether these small fragments can stabilize the closed conformation of flaps in resistant forms of the enzyme. Here we performed Molecular Dynamics simulations of wild type and mutant form of HIV‐PR bound to inhibitor TL‐3. Simulations show that on going from wild type to 6X mutant the equilibrium shifts from closed to semi‐open conformation of flaps. However, when fragment Br6 is placed at flap site of mutant form, the enzyme is restored back to closed conformation. This finding supports the hypothesis that allosteric inhibitors, together with active site inhibitors could increase the number of point mutations necessary for appreciable clinical resistance to AIDS therapy.
GlucoCEST imaging with on‐resonance variable delay multiple pulse (onVDMP) MRI
Authors: Xu Xiang , Xu Jiadi , Chan Kannie W.Y. , Liu Jing , Liu Huanling , Li Yuguo , Chen Lin , Liu Guanshu , van Zijl Peter C.M. 
Published: July 2018

PurposeTo examine the detection sensitivity for the rapidly exchanging hydroxyl protons of D‐glucose using the recently developed on‐resonance variable delay multi‐pulse (onVDMP) chemical exchange saturation transfer (CEST) technique.MethodsThe onVDMP method was applied for the detection of water signal changes upon venous D‐glucose infusion in mice with 9L glioma xenografts. The effect size of onVDMP MRI during infusion was compared with that of conventional continuous wave (CW) CEST MRI.ResultsBoth methods highlighted the tumor and the blood vessels on D‐glucose infusion. In interleaved studies, the mean signal changes detected by onVDMP were found to be 1.8 times higher than those by CW‐CEST, attributed to its high labeling efficiency for fast exchanging protons and the labeling of the OH protons over a larger frequency range.ConclusionsThe onVDMP method is a more sensitive technique for the detection of exogenous CEST agents with fast‐exchanging protons compared to CW‐CEST MRI.
Prevalence of carpal tunnel syndrome presenting with symptoms in an ulnar nerve distribution: A prospective study
Authors: Colorado Berdale S. , Osei Daniel A. 
Published: July 2018

ABSTRACTIntroductionPatients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution may be noted to have exclusive median mononeuropathy at the wrist on subsequent electrodiagnostic testing. There has been limited research looking at the prevalence of this clinical presentation.MethodsA cohort of adults were surveyed to assess for severity and localization of hand symptoms using the Katz hand diagram and Boston Carpal Tunnel Questionnaire Symptoms Severity Scale. Thirty volunteers met our case definition for ulnar neuropathy and underwent a standardized physical examination, electrodiagnostic testing, and nerve ultrasound.ResultsEleven of 30 subjects (37%) were found to have exclusive median mononeuropathy at the wrist.DiscussionCarpal tunnel syndrome should remain high on the differential for patients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution. Muscle Nerve 59:60–63, 2019
Administration of leuprolide acetate, a GnRH agonist, improves urodynamic parameters in ovariectomized rats
Authors: Medina‐Aguiñaga Daniel , Munoz Alvaro , Luna Maricela , Martinez‐Moreno Carlos G. , Quintanar‐Stephano Andrés , Quintanar J. Luis 
Published: July 2018

AimTo evaluate the effects of a treatment with leuprolide acetate (LA) on bladder overactivity as well as the expression of gonadotropin releasing hormone receptor (GnRH‐R), and neurofilaments NF68 and NF200 in female rats with overactive bladder induced by castration.MethodsChanges in the urodynamic parameters were determined in SHAM, ovariectomized (OVX) and ovariectomized rats treated with LA (OVX‐LA). A semi‐quantitative analysis for the expression pattern of GnRH‐R and neurofilaments NF68 and NF200 were determined.ResultsForty‐three days after ovariectomy, rats from the OVX group have significant lower values for intercontractile interval (ICI) and compliance (C); as well as higher values for basal bladder pressure (BP) and frequency of non‐voiding contractions (NVC). The systemic application of LA increased voiding volume (Vv) and pressure threshold (ThP) in the OVX‐LA animals. The application of LA reduced the high frequency of NVC in the OVX rats. No significant differences were found for Vv and NVCs between the OVX‐LA vs SHAM groups. At the mid part of the bladder, the presence of GnRH‐R was evidenced in the urothelium of the SHAM group. The OVX animals showed different pattern of immunolabeling for GnRH‐R as well as for neurofilaments NF200 and NF68, whereas in the OVX‐LA group the immunofluorescence pattern was similar to the one seen in SHAM bladders (P < 0.05 for OVX vs OVX + LA).Conclusionsthe results suggest that systemic application of LA can improve bladder dysfunction in castrated rats, and perhaps considered as a treatment for overactive bladder conditions secondary to menopause.
High‐resolution echo‐planar spectroscopic imaging at ultra‐high field
Authors: Coello Eduardo , Noeske Ralph , Burns Brian L. , Gordon Jeremy W. , Jakary Angela , Menze Bjoern , Haase Axel , Larson Peder E.Z. , Li Yan , Schulte Rolf F. 
Published: July 2018

MR spectroscopic imaging (MRSI) at ultra‐high field (≥7 T) benefits from improved sensitivity that allows the detection of low‐concentration metabolites in the brain. However, optimized acquisition techniques are required to overcome inherent limitations of MRSI at ultra‐high field. This work describes an optimized method for fast high‐resolution 1H‐MRSI of the brain at 7 T. The proposed acquisition sequence combines precise volume localization using semi‐localization by adiabatic selective refocusing, fast spatial encoding using high‐bandwidth symmetric echo‐planar spectroscopic imaging (EPSI), and robust water suppression with variable power and optimized relaxation delays. This showed improved robustness to B0 and B1+ inhomogeneities, eddy currents, nuisance signal contamination and system instabilities. Furthermore, a method for correction of phase inconsistencies in symmetric EPSI enabled high‐bandwidth measurements at 7 T. The proposed correction effectively removed spectral ghosting using a single‐shot water reference scan. This framework was tested in healthy volunteers at 7 T and spectral quality was compared with lower‐spatial‐resolution scans, measured at 3 T using the same methodology. A gain in the signal‐to‐noise ratio (SNR) per unit volume and unit time of 1.57 was achieved, keeping acquisition time short (5 min) and the specific absorption rate within the permitted limits. This SNR enhancement obtained at ultra‐high field enabled high‐resolution (0.25–0.375 mL) metabolite mapping of the brain within a clinically feasible scan time. The correlation of the reconstructed maps with anatomical structures was observed, showing the diagnostic potential of the technique.
A robust deconvolution method to disentangle multiple water pools in diffusion MRI
Authors: De Luca Alberto , Leemans Alexander , Bertoldo Alessandra , Arrigoni Filippo , Froeling Martijn 
Published: July 2018

The diffusion‐weighted magnetic resonance imaging (dMRI) signal measured in vivo arises from multiple diffusion domains, including hindered and restricted water pools, free water and blood pseudo‐diffusion. Not accounting for the correct number of components can bias metrics obtained from model fitting because of partial volume effects that are present in, for instance, diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI). Approaches that aim to overcome this shortcoming generally make assumptions about the number of considered components, which are not likely to hold for all voxels. The spectral analysis of the dMRI signal has been proposed to relax assumptions on the number of components. However, it currently requires a clinically challenging signal‐to‐noise ratio (SNR) and accounts only for two diffusion processes defined by hard thresholds. In this work, we developed a method to automatically identify the number of components in the spectral analysis, and enforced its robustness to noise, including outlier rejection and a data‐driven regularization term. Furthermore, we showed how this method can be used to take into account partial volume effects in DTI and DKI fitting. The proof of concept and performance of the method were evaluated through numerical simulations and in vivo MRI data acquired at 3 T. With simulations our method reliably decomposed three diffusion components from SNR = 30. Biases in metrics derived from DTI and DKI were considerably reduced when components beyond hindered diffusion were taken into account. With the in vivo data our method determined three macro‐compartments, which were consistent with hindered diffusion, free water and pseudo‐diffusion. Taking free water and pseudo‐diffusion into account in DKI resulted in lower mean diffusivity and higher fractional anisotropy values in both gray and white matter. In conclusion, the proposed method allows one to determine co‐existing diffusion compartments without prior assumptions on their number, and to account for undesired signal contaminations within clinically achievable SNR levels.
Detecting stress injury (fatigue fracture) in fibular cortical bone using quantitative ultrashort echo time‐magnetization transfer (UTE‐MT): An ex vivo study
Authors: Jerban Saeed , Ma Yajun , Nazaran Amin , Dorthe Erik W. , Cory Esther , Carl Michael , D'Lima Darryl , Sah Robert L. , Chang Eric Y. , Du Jiang 
Published: July 2018

Bone stress injury (BSI) incidents have been increasing amongst athletes in recent years as a result of more intense sporting activities. Cortical bone in the tibia and fibula is one of the most common BSI sites. Nowadays, clinical magnetic resonance imaging (MRI) is the recommended technique for BSI diagnosis at an early stage. However, clinical MRI focuses on edema observations in surrounding soft tissues, rather than the injured components of the bone. Specifically, both normal and injured bone are invisible in conventional clinical MRI. In contrast, ultrashort echo time (UTE)‐MRI is able to detect the rapidly decaying signal from the bone. This study aimed to employ UTE‐MRI for fatigue fracture detection in fibula cortical bone through an ex vivo investigation. Fourteen human fibular samples (47 ± 20 years old, four women) were subjected to cyclic loading on a four‐point bending setup. The loading was displacement controlled to induce −5000 ± 1500 μ‐strain at 4 Hz. Loading was stopped when bone stiffness was reduced by 20%. Fibula samples were imaged twice, using UTE‐MRI and micro‐computed tomography (μCT), first pre‐loading and second post‐loading. After loading, the macromolecular fraction (MMF) from UTE‐MT modeling demonstrated a significant decrease (12% ± 20%, P = 0.02) on average. Single‐component T2* also decreased significantly by BSI (12% ± 11%, P = 0.01) on average. MMF reduction is hypothesized to be a result of collagenous matrix rupture and water increase. However, faster T2* decay might be a result of water shifts towards newly developed microcracks with higher susceptibility. Despite this good sensitivity level of the UTE‐MRI technique, the μCT‐based porosity at a voxel size of 9 μm was not affected by loading. UTE‐MRI shows promise as a new quantitative technique to detect BSI.