PHYTOCHEMICAL CONSTITUENTS OF THE LEAVES OF LEUCAENA LEUCOCEPHALA FROM MALAYSIA

Objective: This study was conducted to identify the phytochemical constituents of Leucaena leucocephala leaf extracts using gas chromatography-mass spectrometry (GC-MS).Methods: Hexane, petroleum ether, chloroform, ethyl acetate and methanol leaves extract of L. leucocephala were analyzed using GC-MS, while the mass spectra of the compounds found in the extract were matched with the National Institute of Standards and Technology (NIST) library.Results: GC-MS analysis of L. leucocephala leaves revealed the presence of 30 compounds and the major chemical constituents were Squalene (41.02%), Phytol (33.80%), 3,7,11,15-Tetramethyl-2-hexadecen-1-ol (30.86%) and 3,7,11-Tridecatrienenitrile, 4,8,12-trimethyl (25.64%). Some of these compounds have been reported to possess various biological activities such as antioxidant, antimicrobial, hepatoprotective, antiparasitic, insecticide, nematicide, pesticide, anti coronary, antiarthritic, antiandrogenic, hypocholesterolemic, cancer preventive, anti-cancer, analgesic, anesthetic, allergenic and etc.Conclusion: The findings of this study indicating that L. leucocephala leaves possess various potent bioactive compounds and is recommended as a plant of phytopharmaceutical importance

A proposed optimized equivalent circuit and performance analysis of dielectric barrier discharge ozone generator

Traditionally, low-frequency power supplies are used in dielectric barrier discharge (DBD) ozone generators. These generators require a very high output voltage. This may limit ozone production due to limitations imposed by the dielectric strength of the insulating material. Low-frequency generators also present low efficiency, large volumes, and difficulty in controlling ozone production. On the other hand, the advantages of high frequency DBD ozone generators are the increased power density applied to the chamber electrodes, and the voltage applied to the ozone chamber decreases, allowing for higher ozone production efficiency. From this point of view, in order to enhance and control the DBD ozone generator operating at high frequency, it is necessary to determine all parameter values and optimize the equivalent model for this type of generator. This work presents and proposes the practical methodologies used to extract all parameters of the high voltage high frequency (HVHF) transformer which can be used in these systems. Resonant frequency control techniques are presented in this paper. Elimination of the stray capacitance effect will also be implemented in this paper

Conceptualising the panic buying phenomenon during COVID-19 as an affective assemblage

Purpose-This study aims to conceptualise the panic buying behaviour of consumers in the UK during the novel COVID-19 crisis, using the assemblage approach as it is non-deterministic and relational and affords new ways of understanding the phenomenon. Design/methodology/approach-The study undertakes a digital ethnography approach and content analysis of Twitter data. A total of 6,803 valid tweets were collected over the perio

Leptin, insulin like growth factor-1 and thyroid profile in a studied sample of Egyptian children with Down syndrome

Background: Several mechanisms have been suggested for obesity in Down syndrome. Aim of the study: Assessment of serum levels of leptin, insulin like growth factor-I (IGF-I), thyroid stimulating hormone (TSH) and free thyroxin (FT4) in a prepubertal Egyptian sample of children with DS compared to their age and sex matched healthy controls and sibs of some of them.Subjects and methods: A prospective case control study was conducted on 80 children, classified as follows: Groups I & II: enrolled 20 cases with DS for each, sibs were studied only for group I, Group III: 20 healthy siblings of group I, and Group IV: 20 healthy controls. Anthropometric measurements, serum leptin, IGF-1, TSH, and FT4 assessment using enzyme linked immuno-sorbent assay (ELISA) were carried out for all studied children.Results: DS children whether with studied sibs or without studied sibs had significantly higher mean values of leptin levels compared to sibs of group I & IV (P = 0.0001 for all). Meanwhile, mean values of IGF-I showed statistically insignificant differences between all studied groups (p> 0.05 for all). Studied DS children whether with studied sibs or without studied sibs had significantly higher mean values of TSH levels compared to sibs of group I and controls (P = 0.0001 for all). Mean values of FT4 were significantly higher in enrolled DS without their studied sibs compared to sibs of group I (p= 0.01), while mean values of FT4 were significantly lower in sibs of group I compared to controls (p= 0.001).Conclusion: Serum leptin levels were significantly higher in studied DS children compared to both studied sibs and healthy controls and they were also positively correlated with BMI in studied DS children and their sibs highlighting a possible role of body fat% and leptin values in the pathogenesis of obesity in DS children.Keywords: Leptin; IGF-I; TSH; FT4; Obesity; Down syndrom

Comparative Study of Sensorless Control Methods of PMSM Drives

Recently, permanent magnet synchronous motors (PMSMs) are increasingly used in high performance variable speed drives of many industrial applications. This is because the PMSM has many features, like high efficiency, compactness, high torque to inertia ratio, rapid dynamic response, simple modeling and control, and maintenance-free operation. In most applications, the presence of such a position sensor presents several disadvantages, such as reduced reliability, susceptibility to noise, additional cost and weight and increased complexity of the drive system. For these reasons, the development of alternative indirect methods for speed and position control becomes an important research topic. Many advantages of sensorless control such as reduced hardware complexity, low cost, reduced size, cable elimination, increased noise immunity, increased reliability and decreased maintenance. The key problem in sensorless vector control of ac drives is the accurate dynamic estimation of the stator flux vector over a wide speed range using only terminal variables (currents and voltages). The difficulty comprises state estimation at very low speeds where the fundamental excitation is low and the observer performance tends to be poor. The reasons are the observer sensitivity to model parameter variations, unmodeled nonlinearities and disturbances, limited accuracy of acquisition signals, drifts, and dc offsets. Poor speed estimation at low speed is attributed to data acquisition errors, voltage distortion due the PWM inverter and stator resistance drop which degrading the performance of sensorless drive. Moreover, the noises of system and measurements are considered other main problems. This paper presents a comprehensive study of the different methods of speed and position estimations for sensorless PMSM drives. A deep insight of the advantages and disadvantages of each method is investigated. Furthermore, the difficulties faced sensorless PMSM drives at low speeds as well as the reasons are highly demonstrated. Keywords: permanent magnet, synchronous motor, sensorless control, speed estimation, position estimation, parameter adaptation

Transparency of law making and fiscal democracy in the Middle East

Fiscal democracy is the capacity of the legislature to make budgetary choices in response to the emerging needs of citizens. This study indicates that, in Middle Eastern countries, there are specific limitations to fiscal democracy in the process of law-making: most notably the lack of attention to financial impact assessments (FIAs). Without systematic FIAs, mandatory out-of-budget allocations are inadvertently included in public spending, as they do not require parliamentary approval within the regular budgeting process. The low level of effective citizens’ engagement in the process of law-making worsens the situation. Budgetary decisions are not well informed by national priorities and preferences. This study utilizes the dataset of the Open Budget Index (OBI) to measure the quality of the law-making process of the budget law in a sample of Middle Eastern countries. The study concludes with recommendations on mapping the law-making process to increase budget transparency

SELF-ASSEMBLING HYDROGELS BASED ON Î’-CYCLODEXTRIN POLYMER AND POLY (ETHYLENE GLYCOL) BEARING HYDROPHOBIC MOIETIES FOR PROTEIN DELIVERY

Objective: The development of injectable and stable hydrogels for protein delivery is a major challenge. Therefore, the objective of this study was to evaluate the potential of polymerized β-CD for the formulation of stable hydrogels suitable for loading and release of bioactive agents and to investigate the mechanism of hydrogel formation. Methods: Hydrogels based on the inclusion complexation of polymerized β-cyclodextrin and cholesterol terminated poly(ethylene glycol) polymers were formed by rehydration of a lyophilized mixture of both polymers. The mechanism of hydrogel formation was investigated via isothermal titration calorimetry, fluorescence spectroscopy and dynamic light scattering measurements. The release behavior of bovine serum albumin (BSA) as a model protein from the modified gels was explored. Results: Rheological analysis demonstrated that the prepared hydrogels had a viscoelastic behavior even at elevated temperature (> 37 ˚C). There are two competing mechanisms for hydrogel formation. The first mechanism is the inclusion complexation between cholesterol moieties and β-CD cavities. The second one is the self association of cholesterol modified PEGs. β-CD had the ability to dissociate the PEG-cholesterol associations. The quantitative and complete release of BSA was observed within 4 weeks. Conclusion: The polymerized form of β-CD, rather than native β-CD is essential for the formation of stable hydrogels. These results were supported by the ability of the modified hydrogel system for loading and release of BSA, making such hydrogel systems promising devices in drug delivery applications

Neuroimaging of endogenous lapses of responsiveness,

Attention lapses (ALs) and microsleeps (MSs) are complete lapses of responsiveness in which performance is completely disrupted for a short period of time, but consciousness is retained in the case of ALs. ALs are behaviourally different from MSs, as in an AL the eyes remain open whereas in a MS eyes are partially or completely closed. Both ALs and MSs can result in catastrophic consequences, especially in the transportation sector. Research over the past two decades has investigated the AL and MS phenomena using behavioural and physiological means. However, both ALs and MSs need further investigation to separate the different types of ALs physiologically, and to explore the neural signature of MSs in relation to normal sleep and drowsiness. Hence, the objective of this project was to understand the underlying physiological substrates of endogenous (internal) ALs and MSs which could potentially result in differentiating types of ALs and provide more understanding of MSs. Data from two previous Christchurch Neurotechnology Research Programme (NeuroTech™) studies (C and D) were combined resulting in a total of 40 subjects. During each session, subjects performed a 2-D continuous visuomotor tracking (CVT) task for 50 min (Study C) and 20 min (Study D). For each participant, tracking performance, eye-video, EEG, and fMRI were simultaneously collected. A human expert visually inspected the tracking performance and eye-video recordings to identify and categorize lapses of responsiveness for each participant. Participants performed the 2-D CVT task without interruptions. The repetitive nature of the task and the lack of a motivational factor made the task monotonous and fatiguing. As a result, it was more likely to introduce boredom leading to task-unrelated thoughts (TUTs), which divides attention between the task and the internal thoughts unrelated to the task, also fatigue which will introduce a trend of vigilance decrement over time. The project had hypotheses focusing on the changes in the brain’s activity compared to the baseline of good responsiveness tracking. We expected a decrease in dorsal attention network (DAN) activity during ALs due to a decoupling of attention from the external environment. Furthermore, we hypothesized that the ALs were due to involuntary mind-blanks. As such, we expected no change in default mode network (DMN) activity, as would have otherwise been expected if the ALs were due to mind-wandering. Functional connectivity (FC) of the brain was also investigated between the networks of interest which were the DMN, DAN, frontoparietal network (FPN), sensorimotor network (SMN), visual network (VSN), salience network (SN), eye-movement network (EMN), and working memory network (WMN), by analysing data from fMRI. EEG data were also used to perform analysis on ALs and MSs, by analysing changes in power in the delta, theta, alpha, beta, and gamma bands. Voxel-wise fMRI throughout the whole brain, group-ICA, haemodynamic response (HR) over the regions of interest (ROIs), and FC analyses were performed to reveal the neural signature during ALs. In voxel-wise analysis, a significant increase in activity was found in two regions: the dorsal anterior cingulate cortex (dACC) and the supplementary motor area (SMA). The group-ICA analysis did not show any significant results but did show a trend of increased activity in an independent component (IC) that was spatially correlated with SMN. Dynamic HR analysis was performed to further investigate findings from the voxel-wise analysis. Our results were not significant but there were strong trends of change. There was a trend of increased HR 7.5 s after the onset of the AL in the left intraparietal sulcus (IPS) of the DAN. There was also a decrease of 2.5 s before the onset of the AL in the right posterior parietal cortex (PPC) of the FPN. There was also an increase in the HR 5 s after the onset of the AL in the dACC of the SN. Finally, an increase in the HR 15 s before the onset of ALs in the left inferior parietal lobule (IPL) of the DMN is a major finding, as it is an indication that a lapse is about to happen. The HR analysis provided consistent findings with the voxel-wise analysis. FC analysis showed increases in FC within all networks of interest during the ALs. On looking at FC between networks, there was an increase in FC between the DMN and the FPN, no change between the DAN and the FPN, a decrease in FC between the SMN and the FPN, and an increase in FC between the FPN and the VSN. The EMN had an increased FC with the DMN, while it had both increases and decreases in FC with the DAN. There was also an increase in FC between the SN and the DAN, and no change between the SN and the DMN. Finally, a decrease in FC was found between the WMN and the DMN. These findings indicate an overlap between decoupling due to ALs and the process of recovery from ALs. The EEG analysis showed no significant change in the relative difference between average spectral power during ALs and their average baselines for any band of interest for ALs. During MSs, there was a significant increase in power relative to responsive baselines in the delta, theta, alpha, beta, and gamma bands. However, we could not be completely sure that all motion-related artefacts had been removed. Hence, we investigated this further by removing the effect of the global signal, which left only an increase in gamma activity, in addition to a trend of decreased activity in the alpha band. The significant increase in BOLD seen in the voxel-wise analysis is considered to represent the recovery of responsiveness following ALs. This was also seen in trends in group ICA and HR analyses. Overall, findings from the FC analysis show that, in addition to decoupling during ALs, and recovery from ALs, it is highly likely that the ALs during the 2-D CVT task were due to involuntary mind-blanks. This is supported by three major findings: (1) no significant increase in DMN activity in both voxel-wise and HR analyses, (2) the decrease in the HR in the FPN prior to the onset of the AL, and (3) the decrease in FC between the DMN and the WMN. This is further supported behaviourally by the short average duration of ALs (~ 1.7 s), in contrast to what would be likely during mind-wandering. Finally, the significant results from the EEG analysis of MSs, agreed with the literature in delta, theta, and alpha bands. However, increased power in beta and gamma bands was an important finding. We consider this increased high-frequency activity reflects unconscious ‘cognitive’ activity during a MS aimed at restoring consciousness after having fallen asleep during an active task. This highlights a key behavioural and physiological difference between MSs and sleep. Even after removing the effect of the global signal, we still believe that MSs and sleep are physiologically different in the recovery process. To summarize our key findings: (1) this is the first study to demonstrate that ALs during a continuous task are likely to be due to involuntary mind-blanks, (2) the increase in the HR in the DMN 15 s before the onset of AL could be a predictive signature of these lapses, and finally (3) MSs are physiologically different from sleep in terms of the recovery process. This project has improved our understanding of endogenous ALs and MSs and taken us a step closer to accurate detection/prediction systems which can increase prevention of fatal accidents

Smart Touch Radiofrequency Catheter Ablation versus Cryoballoon Ablation of Pulmonary Veins in Patients with Paroxysmal Atrial Fibrillation

AIM: Evaluation of the safety and efficacy of pulmonary veins isolation in patients with paroxysmal atrial fibrillation (AF) using two new different technologies, cryoballoon (CB) ablation and radiofrequency ablation with contact force (CF)-sensing catheters. METHODS: Prospective single-center evaluation, carried out from January 2016 to June 2018 in Critical Care Medicine Department – Cairo University, comparing CF radiofrequency (Thermocool® SmartTouch, Biosense Webster, Inc.) (CF group) with CB ablation (Arctic Front Advance 28 mm CB, Medtronic, Inc.) (CB group), in regards to procedural safety and efficacy, as well as recurrence at 12 months. Overall, 50 consecutive patients were enrolled (25 in each group). RESULTS: The characteristics of patients of both the groups were similar (46.9 ± 11.2 years, the proportion of women 36%, mean documented AF duration 3 ± 2.3 years, mean CHA2DS2-VASc score 1.4 ± 1.3, and mean HAS-BLED 1.4 ± 0.6). Duration of the procedure was significantly lower in the CB group (171.7 ± 15.24 vs. 199.3 ± 18.94 min, p = 0.002), with a longer duration of fluoroscopy and X-ray exposure in the CB group than the CF group but statistically non-significant difference (58.60 ± 11.57 vs. 48.7 ± 13.86 min and 6273 ± 4934 cGy cm² vs. 6853 ± 5069 cGy cm², p = 0.1 and p = 0.2, respectively). Overall complication rate was similar in both groups: 2 (8%) in each group. At 12 months, AF recurrence occurred in 7 patients (28%) in the CF group and in 9 patients (36%) in the CB group (log rank p = 0.682). CONCLUSION: Pulmonary vein isolation using CF-guided RF and second-generation CB leads to comparable single-procedure arrhythmia-free survival at up to 12 months with similar overall complication rate

GC-MS ANALYSIS OF PHYTOCHEMICAL CONSTITUENTS IN LEAF EXTRACTS OF NEOLAMARCKIA CADAMBA (RUBIACEAE) FROM MALAYSIA

Neolamarckia cadamba is one of the medicinal plants used in the treatment of various diseases traditionally. This study was conducted to identify the phytochemical constituents of N. cadamba leaf extracts using gas chromatography mass spectrometry (GC-MS). Solvents with increasing polarities viz. hexane, petroleum ether, chloroform, ethyl acetate and methanol were used in this study. The solvent extracts were analyzed using GC-MS and the mass spectra of the compounds found in the respective extract were matched with the National Institute of Standards and Technology (NIST) library. A total of 26 compounds were identified and the major chemical constituents were n-hexadecanoic acid (44.88%), hexadecanoic acid ethyl ester (17.96%) and octadecanoic acid ethyl ester (11.71%). Some of the identified compounds have been reported to possess various biological activities such as antioxidant, antimicrobial, anesthetic, antiseptic, antidiabetic, hypocholesterolemic and etc. The results thus concluded that N. cadamba leaves possess various potent bioactive compounds and is recommended as a plant of phytopharmaceutical importance