Michael Cyclization of Polarized Systems: Synthesis and in vitro Anti-Diabetic Evaluation of Some Novel Pyrimidine, Pyridine, Pyrazole and Pyrazolo[3,4-b ]pyridine Derivatives

Various interesting heterocycle skeletons were synthesized via Michael type addition reaction with 1,2; 1,3-bidentate nitrogen and carbon nucleophiles. Cycloaddition of different α,β–unsaturated systems afforded bromopyrimidinone 3/5, bromothiazine 4 and bromopyrazole 6a/6b pyrazole-1-carboxylate 8, pyridinylmethanone 9, nicotinonitrile 10, pyrazolopyridine 11a/11b, pyran-3-carbonitrile 12/13, chromenopyridine 14 and N-butyrylpyrazolyl-1-butanone 15 derivatives. The structures of the synthesized compounds were elucidated based on IR, NMR and mass spectral analyses. Group of the newly synthesized compounds were screened for their anti-diabetic activities, whereas compounds 8 and 11b exhibited promising anti-diabetic activities at micro molar concentration against α-glucosidase inhibitor with IC50 values ranging between 13.80-500 μM. On the other hand compound 10 showed a week effect as compared to the standard anti-diabetic agent. This work is licensed under a Creative Commons Attribution 4.0 International License

Synthesis of some new quinoxalines with expected pharmacological activities

4-Methylphenylenediamine 1 was reacted with α-dicarbonylsto give quinoxalines 2a-g, 4a-d and/or 7a-c.Quinoxalines 7a-c were converted into dihydropyridazinoquinoxalines 9a-c, thienoquinoxalines 10a-c and/or dichloroquinoxalines 11a-c. Compounds 11a-c were converted into ethoxyquinoxalines 12a-c, arylaminoquinoxalines13a-f and/or quinazolinoquinoxalines 14a-c. The reaction of 11a-c with semicarbazide and/or sodium azide was also described

Thermal analysis of a flat-plate boiling collector having sub-cooled inlet and saturated exit states

The analysis of the thermal performance of a boiling flat-plate solar collector is presented. A generalized heat removal factor and a new formulation for the overall thermal loss coefficient are developed. It is demonstrated that the conventional heat removal factor for non-boiling collectors is a limiting case of a more generalized result. The new formulation for the overall thermal loss coefficient is shown to be a function of the fractional non-boiling length of the flow channel. The influence of the inlet sub-cooling is evaluated and the operating limits of solar flat-plate collectors are determined. A comparison is made between the thermal model for boiling collectors having sub-cooled inlet states and experimental results. Favorable agreement is obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28137/1/0000588.pd

Thermal analysis of a flat-plate collector in multiphase flows, including superheat

A thermal analysis of the performance of a solar flat-plate collector operating in nonboiling, boiling, and superheated regimes is presented. The performance of the collector under these single and multiphase conditions is governed by the axial fractional channel lengths of the subcooled (nonboiling) and the superheated regions. The overall thermal loss coefficient, the dimensionless capacitance rate, and collector efficiency factors for various collector operating regions are defined. A new "Generalized Heat Removal Factor," Fs, and a new overall thermal loss coefficient, UL, for flat-plate collectors under any operation mode are developed. The thermal efficiency a flat-plate collector, whether under nonboiling, boiling, or superheated conditions, is evaluated using, Fs and UL. It is shown that the value of Fs decreases and the value of UL increases as the degree of superheat increases. Current applications of flat-plate collectors having multiphase flows are represented by those charged with refrigerants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27542/1/0000586.pd

Provably secure and efficient audio compression based on compressive sensing

The advancement of systems with the capacity to compress audio signals and simultaneously secure is a highly attractive research subject. This is because of the need to enhance storage usage and speed up the transmission of data, as well as securing the transmission of sensitive signals over limited and insecure communication channels. Thus, many researchers have studied and produced different systems, either to compress or encrypt audio data using different algorithms and methods, all of which suffer from certain issues including high time consumption or complex calculations. This paper proposes a compressing sensing-based system that compresses audio signals and simultaneously provides an encryption system. The audio signal is segmented into small matrices of samples and then multiplied by a non-square sensing matrix generated by a Gaussian random generator. The reconstruction process is carried out by solving a linear system using the pseudoinverse of Moore-Penrose. The statistical analysis results obtaining from implementing different types and sizes of audio signals prove that the proposed system succeeds in compressing the audio signals with a ratio reaching 28% of real size and reconstructing the signal with a correlation metric between 0.98 and 0.99. It also scores very good results in the normalized mean square error (MSE), peak signal-to-noise ratio metrics (PSNR), and the structural similarity index (SSIM), as well as giving the signal a high level of security

Long-term validation of a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the rapid detection of SARS-CoV-2 from March 2020 to October 2021 in Central Africa, Gabon

Background: Despite the development of several methods for diagnosing COVID-19, long-term validation of such methods remains limited. In the early phase of the COVID-19 pandemic, we developed a rapid and sensitive diagnostic method based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) methodology, which is suitable for point-of-care application or for use in resource-limited settings to detect SARS-CoV-2. To assess the applicability of the RT-LAMP assay technique to resource-limited regions, such as rural areas in Africa, and to verify the usability of the method against various SARS-CoV-2 variants, the method was validated using clinical samples collected longitudinally during the pandemic.Methodology/Principal findings: First, the sensitivity of the RT-LAMP assay for detecting 10 SARS-CoV-2 variants was evaluated using viral RNA samples extracted from cell culture with a portable battery-supported device, resulting in the successful detection of 20–50 copies of the viral genome within 15 min, regardless of the variant. COVID-19 positive samples collected in Gabon between March 2020 and October 2021 were used to evaluate the sensitivity of the assay and to calculate the copy number of the SARS-CoV-2 genome. More than 292 copies of the viral genome were detected with 100% probability within 15 min in almost all tests.Conclusions: This long-term validation study clearly demonstrated the applicability of the RT-LAMP assay for the clinical diagnosis of COVID-19 in resource-limited settings of Africa, such as rural areas in Gabon. The results show the potential of the assay as a promising COVID-19 diagnostic method, especially in rural and remote regions located far from the official diagnosis facilities in urban or semi-urban areas

The changes in renal function after a single dose of intravenous furosemide in patients with compensated liver cirrhosis

BACKGROUND: Patients with compensated Child-A cirrhosis have sub clinical hypovolemia and diuretic treatment could result in renal impairment. AIM: To evaluate the changes in renal functional mass as reflected by DMSA uptake after single injection of intravenous furosemide in patients with compensated liver cirrhosis. METHODS: Eighteen cirrhotic patients were divided in two groups; eight patients (group 1, age 56 ± 9.6 yrs, Gender 5M/3F, 3 alcoholic and 5 non alcoholic) were given low intravenous 40 mg furosemide and ten other patients (group 2, age 54 ± 9.9, Gender 6M/4F, 4 alcoholic and 6 non alcoholic) were given high 120 mg furosemide respectively. Renoscintigraphy with 100MBq Of Tc 99 DMSA was given intravenously before and 90 minutes after furosemide administration and SPECT imaging was determined 3 hours later. All patients were kept under low sodium diet (80mEq/d) and all diuretics were withdrawn for 3 days. 8-hours UNa exertion, Calculated and measured Creatinine clearance (CCT) were performed for all patients. RESULTS: Intravenous furosemide increased the mean renal DMSA uptake in 55% of patients with compensated cirrhosis and these changes persist up to three hours after injection. This increase was at the same extent in either low or high doses of furosemide. (From 12.8% ± 3.8 to 15.2% ± 2.2, p < 0.001 in Gr I as compared to 10.6% ± 4.6 to 13.5% ± 3.6 in Gr 2, p < 0.001). In 8 patients (45%, 3 pts from Gr 1 and 5 pts from Gr 2) DMSA uptake remain unchanged. The mean 8 hrs UNa excretion after intravenous furosemide was above 80 meq/l and was higher in Gr 2 as compared to Gr 1 respectively (136 ± 37 meq/l) VS 100 ± 36.6 meq/l, P = 0.05). Finally, basal global renal DMSA uptake was decreased in 80% of patients; 22.5 ± 7.5% (NL > 40%), as compared to normal calculated creatinine clearance (CCT 101 ± 26), and measured CCT of 87 ± 30 cc/min (P < 0.001). CONCLUSION: A single furosemide injection increases renal functional mass as reflected by DMSA in 55% of patients with compensated cirrhosis and identify 45% of patients with reduced uptake and who could develop renal impairment under diuretics. Whether or not albumin infusion exerts beneficial effect in those patients with reduced DMSA uptake remains to be determined

A thermal-optical analysis of a compound parabolic concentrator for single and multiphase flows, including superheat

A thermal and optical analysis of the performance of a refrigerant charged Compound Parabolic Concentrator (CPC) for solar applications operating in non-boiling, boiling and super-heated regimes is presented. The performance of the CPC working under these single and multiphase conditions is governed by the axial fractional channel lengths of the non-boiling and the superheating regions. The overall thermal loss coefficient, the dimensionless capacitance rate and collector efficiency factors for various CPC operating regions are defined. A new “Generalized Heat Removal Factor“, ℱ s for solar collectors under any operation mode is developed. The thermal efficiency of a CPC and flat-plate collector, whether under non-boiling, boiling or superheated conditions, is evaluated using ℱ s which enables the selection of a suitable collector design and concentration ratio at some specified operational temperature. It is shown that, in general, a CPC has a greater thermal conversion efficiency than a flat-plate for a given operating condition. Es wird eine thermische und optische Analyse des Verhaltens eines Verbund-Parabol-Kollektors für die Anwendung der Sonnenenergie vorgestellt, der mit Kältemittel im nichtsiedenden, und übehitzten Bereich arbeitet. Das Verhalten dieses unter ein- und mehrphasigen Bedingungen arbeitenden Kollektors wird bestimmt durch den axialen Anteil der Kühl-kanallängen im nichtsiedenden und im überhitzten Zustand. Es werden der mittlere thermische Verlustkoeffizient, die dimensionslose Wärmekapazität sowie die Kollektorwirkungsgrade für verschiedene Zustandsbereiche dieses Parabolspiegels definiert. Ein neuer „verallgemeinerter Wärmeabflußfaktor“, ℱ s , für Sonnenkollektoren, die unter beliebigen Betriebsbedingungen arbeiten, wurde entwickelt. Mit diesem ℱ s Faktor werden der thermische Wirkungsgrad des Parabolkollektors und eines Platten-kollektors bei einphasiger flüssiger Strömung beim Sieden und für überhitzten Dampf berechnet, wodurch es möglich wird, eine geeignete Kollektorauslegung und das dazugehörige Konzentrationsverhältnis bei vorgegebenen Betriebstemperaturen zu wählen. Es wird gezeigt, daß im allgemeinen der parabolische Kollektor einen höheren thermischen Wirkungsgrad besitzt als der Platten-kollektor bei identischen Betriebsbedingungen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46656/1/231_2005_Article_BF01377577.pd