4,158 research outputs found
LC-MS Analysis of Secondary Metabolites of Asphodelus aestivus Brot. (Asphodelaceae) grown wild in Jordan
No full textأُظهرت الدراسات أن نبات أسفوديلوس أيستيفوس بروت يُستخدم على نطاق واسع في الطب التقليدي لخصائصه العلاجية. ومع ذلك، لا يزال هناك نقص في المعرفة حول المكونات الكيميائية النباتية لهذا النبات، خاصة عند نموه في الأردن. في هذه الدراسة، تم استخدام تقنيات الكروماتوغرافيا السائلة المزدوجة مع الطيف الكتلي المتقدمة لدراسة المركبات الاستقلابية الثانوية لهذا النوع من النباتات النامية بريًا في الأردن. كشفت نتائجنا عن وجود سبعة مركبات مختلفة، تشمل مركبات معروفة وأنثرونات وجليكوسيدات معقدة، مما يُبرز التنوع الكيميائي للنبات. تُسهم هذه النتائج في فهمنا لأسفوديلوس أيستيفوس بروت وتُظهر التباين الكيميائي بحسب المناطق، بالإضافة إلى التطبيقات العلاجية المحتملة. وتعتبر هذه الأبحاث إضافة قيمة للمنتجات الطبيعية النباتية من خلال دمج الطرق التحليلية المعاصرة مع المعرفة التقليدية.The phytochemical composition of Asphodelus aestivus Brot., a plant with therapeutic properties in traditional medicine, remains largely unexplored, particularly in the specific environmental conditions of Jordan. This study utilized advanced LC-MS techniques to comprehensively analyze the secondary metabolites of a plant species endemic to Jordan. The development of the LC-MS method involved optimizing parameters such as solvent composition, gradient elution, and ionization techniques to achieve comprehensive metabolite profiling. The method was validated to ensure accurate, precise, sensitive, and specific identification and quantification of the compounds. Our analysis identified seven distinct compounds, including both familiar molecules and more complex anthrones and glycosides. This finding emphasizes the wide range of chemical compounds found in the plant and highlights the distinct chemical variations influenced by regional environmental factors. These findings contribute to our understanding of Asphodelus aestivus Brot. and highlight the potential therapeutic uses of its distinct phytochemical composition. This research makes a significant contribution to the field of plant-based natural products by combining modern analytical methods with traditional medicinal knowledge to investigate the complex phytochemical composition of Asphodelus aestivus
LC compensators for power factor correction of nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples
LC compensators based on transmission loss minimization for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThis paper presents a method employing the penalty function search algorithm to determine the LC compensator value for the optimal power factor correction in nonsinusoidal systems. The objective of the proposed method is to minimize the transmission loss while the power factor and efficiency are taken as constraints and utilized in order to solve the multiobjective optimization problem by transforming it into a single objective one. Examples show that the load nonlinearity can have a significant impact on optimal compensator sizes
LC-API/MS in Drug Metabolism and Pharmacokinetic Studies
No full textThe use of API interfaces with quadrupole mass spectrometers has been shown to give rise to good sensitivity, selectivity, and robustness for the interfacing of LC to MS. Since their introduction in the 1990s the technique has rapidly become widespread, but at the outset of this research programme, there were still a number of problems associated with it, particularly when dealing with complex sample matrices. The aim of this research programme was to study illustrative examples of the kinds of problems associated with the analysis of biological samples using LC-API-MS in an attempt to arrive at strategies which could be employed to eliminate, or at least compensate for, the problems.
Commonly reported problems include the occurrence of matrix effects - a change in response of the target analyte(s) as a result of the presence in the samples of co /late eluting interferences. An investigation which compared ESI with APCI ionisation illustrated a significant drawback in the accepted methodology for the elimination of matrix effects.
Optimal LC conditions for a number of assays may use non-MS-friendly mobile phases. A simple and convenient solution to this problem was found to be the post column addition of organic modifier, which reproducibly and reliably enhanced sensitivity. This approach was initially used for a range of dihydropyridine calcium channel blockers and was subsequently applied to a range of chiral compounds from different therapeutic groups to illustrate that this was applicable as a generic technique for increasing sensitivity (typically by around an order of magnitude) in low organic mobile phases.
Strategies to develop and validate methods for the determination of endogenous analytes in a biological fluid were investigated. This involved the use of a surrogate matrix, to develop a method for the determination of endogenous testosterone in human serum and the use of non-matrix calibration standards for the successful development and validation of a method for the analysis of indolyl 3 acryloylglycine (IAG) in human urine.
As a result of observations suggesting promotion of ionisation of deltamethrin in liver tissue sample extracts, it was postulated that this was due to the presence of high concentrations of surfactants. After confirming the effect, a series of systematic investigations were performed to attempt to understand the mechanism to be able to utilise this as a general method for the enhancement of signal with low sensitivity analytes. It was found that the type of surfactant and concentration used was directly associated with an increased (or decreased) response.
Although there remain a number of problems associated with the use of LC-API-MS, the work undertaken for this thesis has successfully demonstrated a number of techniques that can be applied to overcome these problems. Knowledge of the nature of the sample undergoing analysis, the required analytical conditions, and where required careful application of one of the techniques described will ensure that a robust method can be readily developed
LC-MS/MS analysis of DjlA-HA pull-downs.
No full textGraphical representation of the total spectrum count of various proteins detected by LC-MS/MS upon immunoprecipitation of DjlA-HA from soluble cell lysates using anti-HA affinity matrix. The lysates used were from WT expressing DjlA-HA plus (blue) and minus (grey) NAL, and a WT control without DjlA-HA (red). All the TonB-dependant receptors (TBDRs) are annotated with their respective CCNA_#. The data from the LC-MS/MS analysis are deposited in S5 Data. (PDF)</p
Identification and Separation of the Degradation Products of Vildagliptin Tablets and Raw Material using LC-MS and NMR, and then Exploration of the Corresponding Degradation Pathways
No full textA gradient high performance liquid chromatography (HPLC) method has been developed for the qualitative and quantitative analyses of vildagliptin related substances. This method is based on using of RP-C18 (250 × 4.6 mm×5µm) and gradient elution with phosphate buffer and methanol as mobile phase. Various forced degradation studies were conducted to establish an impurity profile for vildagliptin in the tablet formula. Three degradation products were produced upon exposing vildagliptin to different degradation conditions (acidic, basic, oxidative, photolytic, aqueous and thermal); their structures were characterized using LC-MS and NMR (1H NMR, 13C NMR and DEPT) techniques. Some excipient components, examined in this study, had major effect towards producing any extra new degradation products
Cost-effective applications of power factor correction for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2005 IEEEThe objective of this paper is to propose a new approach for designing passive LC compensators by using the penalty function method as an optimization tool. The performance of the cost-effective passive LC compensator for a constant load depends on the appropriate inductor and capacitor selection. Several design methods are reviewed and a novel design methodology is proposed in this paper. By using the proposed method, the designer can quickly find appropriate parameter values to meet the desired circuit performance. Simulated results show that an appropriate combination of the inductor and capacitor selected by the proposed method can meet the desired power-quality requirement. Different cases of design examples are shown in this paper to verify the performance of the proposed design methodology
Study of Jordan quasigroups and their construction
No full textJordan quasigroups are commutative quasigroups satisfying the identity . In this paper we discuss the basic properties of Jordan quasigroups and prove that (i) every commutative idempotent quasigroup is Jordan quasigroup, (ii) if a Jordan quasigroup Q is distributive then Q is idempotent, (iii) an idempotent entropic quasigroup satisfies Jordan's identity, (iv) a unipotent quasigroup Q satisfying Jordan's identity satisfies left nuclear square property, (vi) if a quasigroup satisfies LC identity, then alternativity ⇔ Jordan's identity, (vii) for a unipotent Jordan quasigroup Q, and (viii) every Steiner quasigroup is Jordan quasigroup. We also prove some properties of the autotopism of Jordan loops. Moreover, we construct an infinite family of nonassociative Jordan quasigroups whose smallest member is of order 6
Antioxidant Activity, Phytochemical Screening, and LC/MS-MS Characterization of Polyphenol Content of Jordanian Habitat of Pennisetum Setaceum Aqueous Leaf Extract
No full textالخلفية: Pennisetum setaceum هو نبات سهل النمو وقابل للتكيف بدرجة كبيرة ويتميز بالسيقان الجميلة والأوراق الملونة. لذلك،تم استخدام هذا النوع كوسيلة خضراء في الحفاظ على التوازن البيئي واستعادته وتطوير التنوع البيولوجي. بالإضافة إلى ذلك،تم التحقق من بعض الاستخدامات الطبية المختلفة لهذا النبات. تم سابقا إجراء بعض الابحاث البسيطة لاستكشاف النشاط المضاد للأكسدة والتركيب الكيميائي النباتي لأوراق هذا النبات.
الأهداف: يهدف هذا البحث إلى تقييم التركيب الكيميائي النباتي وفعالية مضادات الأكسدة للموئل الأردني لنبات P.setaceum. المنهجية: تم تحضير المستخلص المائي للأوراق عن طريق النقع. أجريت اختبارات تحليلية لتحديد المستقلبات الثانوية النشطة بيولوجيا والناتجة عن الأيض الثانوي باستخدام إجراءات مرجعية. تم تحديد نشاط مضاد الاكسدة للجذور الحرة للمستخلص باستخدام مقايسة DPPH (2،2-Diphenyl-1-picrylhydrazyl) ومقارنتها بحمض الأسكوربيك. تم إجراء تحليل LC-MS/MS مع التركيز على المحتوى الفينولي للمستخلص.
النتائج: كشفت الاختبارات التحليلية عن وجود للستيرويدات، ترايتيربينويدات، قلويدات، العفص، الفلافونويد، والبوليفينول، في حين لم يلاحظ وجود الصابونينات. عند تركيز 4 ملغ/مل، كان نشاط مضاد الاكسدة للجذور الحرة للمستخلص 41.32٪ فقط، مقارنة ب 85.54٪ لحمض الأسكوربيك. كشف تحليل LC-MS/MS عن وجود ثمانية مركبات فينولية مختلفة:حمض السكسينيك، وألدهيد البروتوكاتيكويك، وحمض 2،5-ثنائي هيدروكسي بنزويك، و2،3-ترانس-3،4-ترانس-ليوكوسيانيدين، وأبين، وإيزو-أورينتين، وأبيجينين، و5،6،4'-ثلاثي هيدروكسي-7،3'-ديميثوكسي فلافون.
الخلاصة: وجود عدد محدود من المركبات الفينولية في مستخلص P.setaceum قد يفسر ضعف نشاطه المضاد للأكسدة. هناك حاجة إلى مزيد من البحث لتحديد المستقلبات الثانوية الأخرى (غير الفينولية)، والتي من شأنها أن تعزز فهمنا لدور هذا النوع النباتي في التطبيقات الزراعية أو البيئية أو الطبية. Background: Pennisetum setaceum is an easy-grow and highly adaptable plant characterized by ravishing stalks and colorful leaves. Therefore, this species has been utilized as a green solution in preserving and restoring the ecological balance and developing biodiversity. In addition, different medicinal uses of the plant have been investigated. Yet, modest research was performed to explore the antioxidant activity and the phytochemical composition of the plant.
Objectives: The current research aims to evaluate the phytochemical composition and the antioxidant activity for the Jordanian habitat of P. setaceum.
Methods: Aqueous extract of leaves was prepared by maceration. Screening tests for the identification of secondary metabolite content were conducted using standard procedures. The free radical scavenging activity for the extract was determined using DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay and compared with ascorbic acid. The LC-MS/MS analysis was performed focusing on the phenolic content of the extract.
Results: The screening tests revealed the presence of steroids, triterpenoids, alkaloids, tannins, flavonoids, and polyphenols, while saponins were not observed. At a concentration of 4 mg/ml, the free radical scavenging activity for the extract was only 41.32%, compared to 85.54% for ascorbic acid. The LC-MS/MS analysis revealed the presence of eight different phenolic compounds: Succinic acid, protocatechuic aldehyde, 2,5-dihydroxybenzoic acid, 2,3-trans-3,4-trans-leucocyanidin, apiin, iso-orientin, and apigenin, and 5,6,4'-trihydroxy-7,3'-dimethoxyflavone.
Conclusion: The presence of a limited number of phenolic compounds in the P. setaceum extract may explain its weak antioxidant activity. Further research is required to identify other (non-phenolic) secondary metabolites content, which would enhances our understanding of the roles this plant species play in agricultural, ecological, or medical applications.
[Temporary British suspension bridge over Jordan River]
No full textTitle devised by Library staff. (Source: researchers T. Bolen and T. Powers, 2009 and similar Matson negative: LC-M32-1888)On negative sleeve: "Allenby Bridge."Guide card: Allenby & Jordan Bridge.Gift; Episcopal Home; 1978
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