Displaying publications 1 - 20 of 191 in total

Abstract:
Sort:
  1. Sahathevan R, Wan Yahya WNN, Tan HJ, Mohd Ibrahim N
    Med J Malaysia, 2013 Apr;68(2):187-8.
    PMID: 23629577
    Matched MeSH terms: Urea*
  2. Sein KT, Arumainayagam G
    Clin Chem, 1987 Dec;33(12):2303-4.
    PMID: 3690853
    Matched MeSH terms: Urea/analysis*; Urea/blood
  3. Ooi CH, Cheah WK, Sim YL, Pung SY, Yeoh FY
    J Environ Manage, 2017 Jul 15;197:199-205.
    PMID: 28384613 DOI: 10.1016/j.jenvman.2017.03.083
    Urea removal is an important process in household wastewater purification and hemodialysis treatment. The efficiency of the urea removal can be improved by utilizing activated carbon fiber (ACF) for effective urea adsorption. In this study, ACF was prepared from oil palm empty fruit bunch (EFB) fiber via physicochemical activation using sulfuric acid as an activating reagent. Based on the FESEM result, ACF obtained after the carbonization and activation processes demonstrated uniform macropores with thick channel wall. ACF was found better prepared in 1.5:1 acid-to-EFB fiber ratio; where the pore size of ACF was analyzed as 1.2 nm in diameter with a predominant micropore volume of 0.39 cm(3) g(-1) and a BET surface area of 869 m(2) g(-1). The reaction kinetics of urea adsorption by the ACF was found to follow a pseudo-second order kinetic model. The equilibrium amount of urea adsorbed on ACF decreased from 877.907 to 134.098 mg g(-1) as the acid-to-fiber ratio increased from 0.75 to 4. During the adsorption process, the hydroxyl (OH) groups on ACF surface were ionized and became electronegatively charged due to the weak alkalinity of urea solution, causing ionic repulsion towards partially anionic urea. The ionic repulsion force between the electronegatively charged ACF surface and urea molecules became stronger when more OH functional groups appeared on ACF prepared at higher acid impregnation ratio. The results implied that EFB fiber based ACF can be used as an efficient adsorbent for the urea removal process.
    Matched MeSH terms: Urea*
  4. Qureshi S, Mumtaz M, Chong FK, Mukhtar A, Saqib S, Ullah S, et al.
    Chemosphere, 2022 Mar;291(Pt 3):132806.
    PMID: 34780730 DOI: 10.1016/j.chemosphere.2021.132806
    One of the most significant chemical operations in the past century was the Haber-Bosch catalytic synthesis of ammonia, a fertilizer vital to human life. Many catalysts are developed for effective route of ammonia synthesis. The major challenges are to reduce temperature and pressure of process and to improve conversion of reactants produce green ammonia. The present review, briefly discusses the evolution of ammonia synthesis and current advances in nanocatalyst development. There are promising new ammonia synthesis catalysts of different morphology as well as magnetic nanoparticles and nanowires that could replace conventional Fused-Fe and Promoted-Ru catalysts in existing ammonia synthesis plants. These magnetic nanocatalyst could be basis for the production of magnetically induced one-step green ammonia and urea synthesis processes in future.
    Matched MeSH terms: Temperature; Urea*
  5. Nor Aziawati Azahari, Sarani Zakaria, Hatika Kaco, Sin Yee Gan, Chia Chin Hua, Sharifah Nabihah Syed Jaafar, et al.
    Sains Malaysiana, 2017;46:795-801.
    Membran selulosa terjana semula (MS) daripada pulpa teras kenaf telah berjaya dihasilkan menggunakan kaedah pra penyejukan dan digumpal menggunakan larutan asid sulfurik. MS disediakan daripada pelarutan selulosa kenaf dalam larutan akues NaOH/urea dan larutan selulosa seterusnya digumpal dengan H2SO4 pada kepekatan 5-12 peratus berat (% bt.) selama 1-10 min. Pengaruh kepekatan penggumpal H2SO4 dan masa penggumpalan ke atas struktur, saiz liang, sifat mekanik dan ketelusan cahaya MS telah dikaji menggunakan pembelauan sinar-X (XRD), imbasan mikroskop elektron tekanan boleh ubah (VPSEM), penguji regangan dan spektrofotometer ultra-violet sinar tampak (UV-vis). Keputusan VPSEM menunjukkan perubahan saiz liang membran bergantung kepada kepekatan larutan penggumpal H2SO4, manakala masa penggumpalan tidak mempengaruhi saiz liang membran. Membran yang direndam dengan larutan penggumpal pada kepekatan 10 % bt. dan masa pembekuan yang sederhana iaitu 5 min menunjukkan sifat mekanik yang lebih baik dengan nilai kekuatan regangan masing-masing 41.9 dan 43.5 MPa. Oleh itu, kajian ini dapat memberikan maklumat mengenai penyediaan MS dengan pelbagai saiz liang dan sifat mekanik dengan pengubahsuaian kepekatan dan masa penggumpalan.
    Matched MeSH terms: Urea
  6. Alqasaimeh MS, Heng LY, Ahmad M
    Sensors (Basel), 2007 Oct 11;7(10):2251-2262.
    PMID: 28903225 DOI: 10.3390/s7102251
    An optical urea biosensor was fabricated by stacking several layers of sol-gelfilms. The stacking of the sol-gel films allowed the immobilization of a Nile Bluechromoionophore (ETH 5294) and urease enzyme separately without the need of anychemical attachment procedure. The absorbance response of the biosensor was monitoredat 550 nm, i.e. the deprotonation of the chromoionophore. This multi-layer sol-gel filmformat enabled higher enzyme loading in the biosensor to be achieved. The urea opticalbiosensor constructed from three layers of sol-gel films that contained urease demonstrateda much wider linear response range of up to 100 mM urea when compared with biosensorsthat constructed from 1-2 layers of films. Analysis of urea in urine samples with thisoptical urea biosensor yielded results similar to that determined by a spectrophotometricmethod using the reagent p-dimethylaminobenzaldehyde (R² = 0.982, n = 6). The averagerecovery of urea from urine samples using this urea biosensor is approximately 103%.
    Matched MeSH terms: Urea; Urease
  7. Bharati J, Jha V
    Semin Dial, 2020 11;33(6):490-498.
    PMID: 33030777 DOI: 10.1111/sdi.12924
    Dialysis adequacy is conventionally quantified as net urea clearance. Single pool (sp) Kt/Vurea remains the best studied measure of dialysis adequacy globally. Other measures such as fluid status control, anemia correction, and mineral metabolism are monitored variably. Increasing use of hemodiafiltration across Europe and many parts of Japan and Australia is predicated on studies showing better patient survival with middle molecule clearance. Apart from local clinical practice guidelines, the income level and public health policy of a country determine quality of dialysis services. Among developed nations, small solute clearance adequacy targets are achieved with high frequency. In the United States, dialysis adequacy target is met by focussing on high blood flow rates and large dialyzer size, sometimes at the cost of session time. In Japan, Australia, and Germany, session length is given importance. Dialysis adequacy reporting is restricted and inconsistent in developing nations. The Gulf Cooperation Council countries, Russia and Malaysia, respectively, are close to achieving dialysis adequacy target (spKt/Vurea ≥1.2) universally in their dialysis populations. Patient-reported outcomes are typically measured only in developed countries. Patient survival on dialysis, partly linked to dialysis adequacy, varies greatly around the world, with Japan having the best survival rates. Until the development of better markers of dialysis adequacy, universal consistency in reporting of conventional parameters with a focus on patient-reported measures should be endeavored.
    Matched MeSH terms: Blood Urea Nitrogen; Urea
  8. Futane A, Senthil M, S J, Srinivasan A, R K, Narayanamurthy V
    Anal Methods, 2023 Sep 14;15(35):4405-4426.
    PMID: 37646163 DOI: 10.1039/d3ay01089a
    With increasing population there is a rise in pathological diseases that the healthcare facilities are grappling with. Sweat-based wearable technologies for continuous monitoring have overcome the demerits associated with sweat sampling and sensing. Hence, sweat as an alternative biofluid holds great promise for the quantification of a host of biomarkers and understanding the functioning of the body, thereby deducing ailments quickly and economically. This comprehensive review accounts for recent advances in sweat-based LOCs (Lab-On-Chips), which are a likely alternative to the existing blood-urea sample testing that is invasive and time-consuming. The present review is focused on the advancements in sweat-based Lab-On-Chips (LOCs) as an alternative to invasive and time-consuming blood-urea sample testing. In addition, different sweat collection methods (direct skin, near skin and microfluidic) and their mechanism for urea sensing are explained in detail. The mechanism of urea in biofluids in protein metabolism, balancing nitrogen levels and a crucial factor of kidney function is described. In the end, research and technological advancements are explained to address current challenges and enable its widespread implementation.
    Matched MeSH terms: Urea*
  9. Al-Mulla EA, Yunus WM, Ibrahim NA, Rahman MZ
    J Oleo Sci, 2010;59(3):157-60.
    PMID: 20124758
    In this study, difatty acyl urea has been successfully synthesized from corn oil using sodium ethoxide as a catalyst. Ethyl fatty ester and glycerol were produced as by-products. In this reaction, corn oil was refluxed with urea in ethanol. The highest conversion percentage (78%) was obtained when the process was carried out for 8 hours using urea to corn oil ratio of 5.6: 1.0 at 78 degrees C. Both difatty acyl urea and ethyl fatty ester have been characterized using elemental analysis, Fourier transform infrared (FTIR) spectroscopy and (1)H nuclear magnetic resonance (NMR) technique.
    Matched MeSH terms: Urea/chemical synthesis*; Urea/chemistry*
  10. Abg Ahmad DFB, Wasli ME, Tan CSY, Musa Z, Chin SF
    Sci Rep, 2023 Nov 22;13(1):20453.
    PMID: 37993538 DOI: 10.1038/s41598-023-47922-y
    The effect of urea-loaded cellulose hydrogel, a controlled-release fertilizer (CRF) on growth and yield of upland rice were investigated in upland rice. As with the initial research, nitrogen (N) treatments were applied as CRF treatments; T2H (30 kg N ha-1), T3H (60 kg N ha-1), T4H (90 kg N ha-1), T5H (120 kg N ha-1) and recommended dose of fertilizer (RDF) at 120 kg N ha-1 RDF (T6U) in split application and T1 (0 N) as control. Results from this study indicated that applying CRF at the optimum N rate, T4H resulted in maximum grain yield, increasing by 71%. The analysis of yield components revealed that higher grain yield in T4H CRF was associated with an increase in panicle number and number of grains per panicle. Maximum grain N uptake of 0.25 g kg-1 was also observed in T4H CRF. In addition, T4H CRF recorded the highest harvest index (HI) and N harvest index (NHI) of 45.5% and 67.9%, respectively. Application of T4H CRF also recorded the highest N use efficiency (NUE) and N agronomic efficiency (NAE), 52.6% and 12.8 kg kg-1, respectively. Observations show that CRF with only 75% N applied (T4H) in soil improved grain yield when compared to CRF with 100% N and 100% RDF in farmers' conventional split application. This suggested that CRF with a moderate N application might produce the highest potential yield and improved N efficiencies while enhancing crop production and further increase in N supply did not increase yield and N efficiencies. The results suggest that the application of T4H CRF for upland rice would enhance HI, N efficiencies and improve the yield of upland rice. Also, all growth parameters and yield were positively influenced by the application of CRF as a basal dose compared to split application of conventional urea fertilizers.
    Matched MeSH terms: Urea/analysis; Urea/pharmacology
  11. Wong YH, Kadir HA, Tayyab S
    Protein Pept Lett, 2016;23(10):898-904.
    PMID: 27586182
    Urea and thermal denaturations of bovine serum albumin (BSA) were studied in the absence and the presence of honey or simulated honey sugar cocktail (SHSC) using far-UV CD and ANS fluorescence spectroscopy. Presence of 20% (w/v) honey or SHSC in the incubation mixture shifted the urea transition curve towards higher urea concentrations, being higher in the presence of honey and transformed the two-step, three-state transition into a single-step, two-state transition. A comparison of the far-UV CD and the ANS fluorescence spectra of 4.6 M urea-denatured BSA (U-BSA) in the absence and the presence of 20% (w/v) honey or SHSC suggested greater stabilizing potential of honey than SHSC, as U-BSA maintained native like conformation in the presence of 20% (w/v) honey. Furthermore, thermal transition curves of BSA were also shifted towards higher temperature range in the presence of 20% (w/v) SHSC and honey, showing greater shift in the presence of honey. The far-UV CD spectra of the heat-denatured BSA also showed greater stabilization in the presence of honey. Taken together all these results suggested greater protein stabilizing potential of honey than SHSC against chemical and thermal denaturations of BSA.
    Matched MeSH terms: Urea/chemistry
  12. Buttery JE, de Witt GF, Ahmad UO
    Med J Malaya, 1969 Jun;23(4):265-8.
    PMID: 4242173
    Matched MeSH terms: Blood Urea Nitrogen*
  13. Kravchenko I, Rudyk I, Medentseva O
    PMID: 34628401
    Over the past decades, there has been an active scientific search for drugs that can increase myocardial contractility and improve the course of heart failure. Omecamtiv Mecarbil, a drug from the group of cardiac myosin activators, heads the list of applicants for clinical use. The article presents the results of several randomized clinical trials which studied the efficacy and safety of Omecamtiv Mecarbil in heart failure: ATOMIC-AHF, COSMIC-HF and GALACTIC-HF. ATOMIC-AHF showed a tendency to reduce the risk of developing supraventricular and ventricular arrhythmias in heart failure. COSMIC-HF has proven the ability of Omecamtiv Mecarbil to improve the quality of life of patients with heart failure. GALACTIC-HF may be a turning point in the medical treatment of heart failure. For the first time, clinical evidence of the ability of the selective cardiac myosin activator Omecamtiv Mecarbil to improve myocardial contractile function, reduce the severity of symptoms of heart failure and reduce the risk of cardiovascular death was obtained.
    Matched MeSH terms: Urea/analogs & derivatives
  14. Sarwono A, Man Z, Bustam MA, Subbarao D, Idris A, Muhammad N, et al.
    Environ Technol, 2018 Jun;39(12):1522-1532.
    PMID: 28524800 DOI: 10.1080/09593330.2017.1332108
    Coating fertilizer particles with thin films is a possibility to control fertilizer release rates. It is observed that novel urea cross-linked starch-lignin composite thin films, prepared by solution casting, swell on coming into contact with water due to the increase in volume by water uptake by diffusion. The effect of lignin content, varied from 0% to 20% in steps of 5% at three different temperatures (25°C, 35°C and 45°C), on swelling of the film was investigated. By gravimetric analysis, the equilibrium water uptake and diffusion coefficient decrease with lignin content, indicating that the addition of lignin increases the hydrophobicity of the films. When temperature increases, the diffusion coefficient and the amount of water absorbed tend to increase. Assuming that swelling of the thin film is by water uptake by diffusion, the diffusion coefficient is estimated. The estimated diffusion coefficient decreases from 4.3 to 2.1 × 10-7 cm2/s at 25°C, from 5.3 to 2.9 × 10-7 cm2/s at 35°C and from 6.2 to 3.8 × 10-7 cm2/s at 45°C depending on the lignin content. Activation energy for the increase in diffusion coefficient with temperature is observed to be 16.55 kJ/mol. An empirical model of water uptake as a function of percentage of lignin and temperature was also developed based on Fick's law.
    Matched MeSH terms: Urea/chemistry*
  15. Nur Akmar Jamil, Gan SM, Burhanuddin Yeop Majlis, Susthitha Menon P
    Sains Malaysiana, 2018;47:1033-1038.
    Artikel ini menganalisis biosensor resonans plasmon permukaan (SPR) dengan lapisan grafin yang meningkatkan
    kecekapan biosensor urea kerana penerapannya yang tinggi. Tatasusunan Kretschmann merupakan teknik yang paling
    berkesan digunakan untuk pengujaan plasmon. Dalam kajian ini, kami menganalisis kesan ekalapisan MoS2 dengan
    lapisan grafin yang didepositkan pada bahan plasmon, iaitu logam emas (Au), di dalam tatasusunan ini. Simulasi untuk
    menganalisis tatasusunan ini adalah berdasarkan kepada kaedah perbezaan terhingga domain masa (FDTD). Prestasi
    biosensor SPR dapat dipantau dengan menganalisis kepekaan dan lebar penuh pada separuh maksimum (FWHM) spektrum
    SPR. Pengukuran diperhatikan pada panjang gelombang 670 nm dan 785 nm untuk pengesanan urea. Indeks molar dan
    indeks biasan berbeza (RI) daripada 1.335 sehingga 1.342 untuk lapisan penderiaan. Keputusan menunjukkan peratus
    peningkatan kepekaan biosensor Au/MoS2
    /grafin berbanding biosensor Au konvensional adalah 98% dan 202% masingmasing
    pada panjang gelombang 670 nm dan 785 nm. Ini menunjukkan bahawa cadangan biosensor SPR yang novel ini
    adalah lebih sensitif untuk pengesanan urea.
    Matched MeSH terms: Urea
  16. Vadabingi N, Avula VKR, Zyryanov GV, Vallela S, Anireddy JS, Pasupuleti VR, et al.
    Bioorg Chem, 2020 04;97:103708.
    PMID: 32146177 DOI: 10.1016/j.bioorg.2020.103708
    A series of novel α-methyl-l-DOPA urea derivatives viz., 3-(3,4-dihydroxyphenyl)-2-methyl-2-(3-halo/trifluoromethyl substituted phenyl ureido)propanoic acids (6a-e) have been synthesized from the reaction of α-methyl-l-DOPA (3) with various aryl isocyanates (4a-e) by using triethylamine (5, TEA) as a base catalyst in THF at reflux conditions. The synthesized compounds are structurally characterized by spectral (IR, 1H &13C NMR and MASS) and elemental analysis studies and screened for their in-vitro antioxidant activity against DPPH, NO and H2O2 free radical scavenging assays and identified compounds 6c &6d as potential antioxidants. The acquired in vitro results were correlated with the results of molecular docking, ADMET, QSAR and bioactivity studies performed for them and predicted that the recorded in silico binding affinities are in good correlation with the in vitro antioxidant activity results. The molecular docking analysis has comprehended the strong hydrogen bonding interactions of 6a-e with 1CB4, 1N8Q, 3MNG, 1OG5, 1DNU, 3NRZ, 2CDU, 1HD2 and 2HCK proteins of their respective SOD, LO, PRXS5, CP450, MP, XO, NO, PRY5 and HCK enzymes. This has sustained the effective binding of 6a-e and resulted in functional inhibition of selective aminoacid residues to be pronounced as multiple molecular targets mediated antioxidant potent compounds. In addition, the evaluated toxicology risks of 6a-e are identified with in the potential limits of drug candidates. The conformational analysis of 6c & 6d prominently infers that urea moiety uniting α-methyl-l-DOPA with halo substituted aryl units into a distinctive orientation to comply good structure-activity to inhibit the proliferation of reactive oxygen species in vivo.
    Matched MeSH terms: Urea/analogs & derivatives*; Urea/pharmacokinetics; Urea/pharmacology*
  17. Tan SL, Azizan AHS, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2019 Oct 01;75(Pt 10):1472-1478.
    PMID: 31636978 DOI: 10.1107/S2056989019012581
    In the title tri-substituted thio-urea derivative, C13H18N2O3S, the thione-S and carbonyl-O atoms lie, to a first approximation, to the same side of the mol-ecule [the S-C-N-C torsion angle is -49.3 (2)°]. The CN2S plane is almost planar (r.m.s. deviation = 0.018 Å) with the hy-droxy-ethyl groups lying to either side of this plane. One hy-droxy-ethyl group is orientated towards the thio-amide functionality enabling the formation of an intra-molecular N-H⋯O hydrogen bond leading to an S(7) loop. The dihedral angle [72.12 (9)°] between the planes through the CN2S atoms and the 4-tolyl ring indicates the mol-ecule is twisted. The experimental mol-ecular structure is close to the gas-phase, geometry-optimized structure calculated by DFT methods. In the mol-ecular packing, hydroxyl-O-H⋯O(hydrox-yl) and hydroxyl-O-H⋯S(thione) hydrogen bonds lead to the formation of a supra-molecular layer in the ab plane; no directional inter-actions are found between layers. The influence of the specified supra-molecular inter-actions is apparent in the calculated Hirshfeld surfaces and these are shown to be attractive in non-covalent inter-action plots; the inter-action energies point to the important stabilization provided by directional O-H⋯O hydrogen bonds.
    Matched MeSH terms: Urea
  18. Mokhtaruddin NS, Ravoof TB, Tahir MI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Apr 1;71(Pt 4):o253-4.
    PMID: 26029441 DOI: 10.1107/S2056989015005034
    In the title hydrate, C9H12N4S·H2O (systematic name: 3-methyl-1-{(E)-[(3-methyl-pyridin-2-yl)methyl-idene]amino}-thio-urea monohydrate), a small twist is noted between the pyridine ring and the rest of the organic mol-ecule [dihedral angle = 6.96 (5)°]. The imine and pyridine N atoms are syn, and the amine H atoms are anti. The latter arrangement allows for the formation of an intra-molecular N-H⋯N(imine) hydrogen bond. Both the N-bonded H atoms form hydrogen bonds to symmetry-related water mol-ecules, and the latter forms O-H hydrogen bonds with the pyridine N and thione S atoms. These inter-actions lead to supra-molecular layers that stack along the a-axis direction with no specific inter-actions between them.
    Matched MeSH terms: Urea
  19. Fatema KN, Jung CH, Liu Y, Sagadevan S, Cho KY, Oh WC
    ACS Biomater Sci Eng, 2020 12 14;6(12):6981-6994.
    PMID: 33320627 DOI: 10.1021/acsbiomaterials.0c00423
    In the present study, electrochemical sensing for urea was proposed utilizing graphene-based quaternary nanocomposites YInWO4-G-SiO2 (YIWGS). These YIWGS nanocomposites were utilized due to their exceptionally delicate determination of urea with the lowest detection limit (0.01 mM). These YIWGS composites were developed through a simple self-assembly method. From physical characterization, we found that the YIWGS composites are crystalline in nature (powdered X-ray diffraction), and Fourier transform infrared (FTIR) spectroscopy analysis provided the surface functionality and bonding. Scanning electron microscopy (SEM) studies indicated the morphology characteristics of the as-synthesized composites and the high-resolution transmission electron microscopy (HRTEM) image supported the formation of cubic or hexagonal morphology of the YIW nanocomposites. The YIWGS sensor showed a great electroanalytical sensing performance of 0.07 mM urea with a sensitivity of 0.06 mA cm-2, an expansive linear range of 0.7-1.5 mM with a linear response (R2 1/4 0.99), and an eminent reaction time of around 2 s. It also displayed a good linear response toward urea with negligible interferences from normal coinciding species in urine samples.
    Matched MeSH terms: Urea
  20. Samaila, Buda, Suhaidi Shafie, Suraya Abdul Rashid, Haslina Jafaar, Ali Khalifa
    MyJurnal
    In this study, nitrogen doped titanium dioxide-based dye-sensitised solar cell was successfully fabricated
    using screen printing technique to discover the optimisation of process parameters for the solar cell
    efficiency using response surface methodology (RSM). Parameter optimisation has been a major concern
    in solar cell fabrication. The selected parameters were: nitrogen concentration (15-25 mg of urea), the
    film thickness (25-60 µm) and dye loading time (12-24 hours), the optimum condition which yields the
    highest efficiency of 3.5% was at 15 mg nitrogen concentration, 25 µm film thickness and 24-hours dye
    loading time. Film thickness was found to have a significant influence on efficiency while the loading
    time exceeding 18 hours has the least significant effect.
    Matched MeSH terms: Urea
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links