Displaying publications 81 - 100 of 286 in total

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  1. Anizaim AH, Zainuri DA, Zaini MF, Razak IA, Bakhtiar H, Arshad S
    PLoS One, 2020;15(11):e0241113.
    PMID: 33147247 DOI: 10.1371/journal.pone.0241113
    Two organometallic compounds known as (E)-1-ferrocenyl-(3-fluorophenyl)prop-2-en-1-one (Fc1) and (E)-1-ferrocenyl-(3-fluoro-4-methoxyphenyl)prop-2-en-1-one (Fc2) are designed and synthesized for application in dye-sensitized solar cell (DSSC) based on a donor-π-acceptor (D-π-A) architecture. By strategically introducing a methoxy group into the acceptor side of the compound, Fc2 which has adopted a D-π-A-AD structure are compared with the basic D-π-A structure of Fc1. Both compounds were characterized by utilizing the IR, NMR and UV-Vis methods. Target compounds were further investigated by X-ray analysis and studied computationally using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) approaches to explore their potential performances in DSSCs. An additional methoxy group has been proven in enhancing intramolecular charge transfer (ICT) by improving the planarity of Fc2 backbone. This good electronic communication leads to higher HOMO energy level, larger dipole moment and better short-circuit current density (Jsc) values. Eventually, the presence of methoxy group in Fc2 has improved the conversion efficiency as in comparison to Fc1 under the same conditions.
    Matched MeSH terms: X-Rays
  2. Abdul Sani SF, Othman MHU, Alqahtani A, Almugren KS, Alkallas FH, Bradley DA
    PLoS One, 2020;15(12):e0241550.
    PMID: 33378398 DOI: 10.1371/journal.pone.0241550
    For x- and gamma- irradiations delivering entrance doses from 2- up to 1000 Gy to commercial 1.0 mm thick borosilicate glass microscope slides, study has been made of their thermoluminescence yield. With an effective atomic number of 10.6 (approximating bone equivalence), photon energy dependency is apparent in the low x-ray energy range, with interplay between the photoelectric effect and attenuation. As an example, over the examined dose range, at 120 kVp the photon sensitivity has been found to be some 5× that of 60Co gamma irradiations, also with repeatability to within ~1%. The glow-curves, taking the form of a single prominent broad peak, have been deconvolved yielding at best fit a total of five peaks, the associated activation energies and frequency factors also being obtained. The results indicate borosilicate glass slides to offer promising performance as a low-cost passive radiation dosimeter, with utility for both radiotherapy and industrial applications.
    Matched MeSH terms: X-Rays
  3. Khezripour S, Rezaie M, Hassanpour M, Hassanpour M, Rashed Iqbal Faruque M, Uddin Khandaker M
    PLoS One, 2023;18(8):e0288287.
    PMID: 37594963 DOI: 10.1371/journal.pone.0288287
    Various atomic and nuclear methods use hard (high-energy) X-rays to detect elements. The current study aims to investigate the hard X-ray production rate via high-energy proton beam irradiation of various materials. For which, appropriate conditions for producing X-rays were established. The MCNPX code, based on the Monte Carlo method, was used for simulation. Protons with energies up to 1650 MeV were irradiated on various materials such as carbon, lithium, lead, nickel, salt, and soil, where the resulting X-ray spectra were extracted. The production of X-rays in lead was observed to increase 16 times, with the gain reaching 0.18 as the proton energy increases from 100 MeV to 1650 MeV. Comparatively, salt is a good candidate among the lightweight elements to produce X-rays at a low proton energy of 30 MeV with a production gain of 0.03. Therefore, it is suggested to irradiate the NaCl target with 30 MeV proton to produce X-rays in the 0-2 MeV range.
    Matched MeSH terms: X-Rays
  4. Zakaria MB, Saito I, Yao XK, Wang RJ, Matsuura T
    Planta Med, 1989 Oct;55(5):477-8.
    PMID: 17262463
    Fibraurin, chasmanthin, and palmarin were isolated from the stems of FIBRAUREA CHLOROLEUCA, Fam. Menispermaceae. The structure of the minor constituent, palmarin, was determined by X-ray crystallographic analysis.
    Matched MeSH terms: X-Rays
  5. Moradi F, Ung NM, Khandaker MU, Mahdiraji GA, Saad M, Abdul Malik R, et al.
    Phys Med Biol, 2017 Jul 28;62(16):6550-6566.
    PMID: 28708603 DOI: 10.1088/1361-6560/aa7fe6
    The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators.

    HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

    Matched MeSH terms: X-Rays
  6. Sayed, I. S., Yusri, N. H.
    MyJurnal
    In radiography, radiation workers are responsible to protect patients and their caregivers from adverse effects of X-rays during diagnostic procedures. The X-ray examination rooms are designated as controlled areas where only authorised persons are allowed to enter. However, sometimes radiographers allow next in-line patients’ and caregivers in X-ray examination room and ask them to stand behind the mobile lead shielding when exposure is on. The objectives of this study were to determine the amount of scatter radiation dose at different heights with respect to the floor in the X-ray examination room and to educate and increase the awareness of radiation workers about the scattered radiation in minimizing the unnecessary radiation dose to patient’s caregivers. Siemens Multix Top X-ray system was used. Kyoto Kagaku PBU-50 whole body phantom was scanned. The phantom (torso) was positioned for anteroposterior (AP) lumbar projection on the examination table. The nanoDot OSLDs were fixed behind the lead shielding at different heights (120, 130, 140, 150, 160 and 170 cm) with respect to the floor 2.5 meters away from the central ray of X-ray beam. The phantom was exposed using different tube voltages 68 kVp, 79 kVp and 90 kVp at a constant tube current of 32 mAs fixing a 100 cm source to image distance (SID). Scatter radiation doses measured at different heights were different for each exposure. The highest scattered radiation dose measured was 6.4 mGy at 130 cm height for 79 kVp exposure. In conclusion the measured scattered radiation doses were within the acceptable annual dose limits as recommended by NCRP 116 and ICRP 103 for patient caregiver. However, a smallest amount of radiation dose may increase the risk of cancer. Thus, the negligence must not be overlooked because it exposes the caregiver to unnecessary radiation.
    Matched MeSH terms: X-Rays
  7. Zin, H. M.
    MyJurnal
    The Malaysian Association of Medical Physics (MAMP) was set up in the year 2000 to promote and further develop the field that was relatively new in Malaysia. The article briefly summarises key developments in medical physics since the first discovery of x-rays in 1895. The resulted rapid progress in the field was also highlighted and related to the pace of development in Malaysia. Key activities organised by MAMP were also addressed. The international practices related to the field and the profession were highlighted and compared to the current status in Malaysia. Although the field has progressed well in the country, there are several gaps identified to further improve the field and the profession in Malaysia.
    Matched MeSH terms: X-Rays
  8. Kamal, I., Salehhon, N., Hashim, S., Musa, Y., Abdul Karim, M. K.
    MyJurnal
    The aimed of this study is to estimate the entrance surface dose (ESD) of routine chest X-ray (CXR) examination and to compare the direct and indirect measurement. This study also extended to relate with the patients body thickness and established lifetime attributable risk (LAR) of the examinations. A total of 101 CXR examinations in posteroanterior (PA) projections were selected
    as subjects and data, such as patient habitus and scanning acquisition parameters were recorded. The mean ESD value obtained from the TLD-100 and the software calculation was 0.31 mGy and 0.17 mGy, respectively. The percentage deviation obtained ranged from 25.5% to 61.3%. In comparison with the national diagnostic reference level (DRL), the mean values of ESD obtained from this study were lower by a factor of 3. Furthermore, it was observed that the mean absorbed dose of the adrenals, kidneys, lungs, oesophagus, and heart walls were lower as compared to the ESD value. The examinations were only associated with very low risk of cancer incidence and mortality. Hence, the results of this study suggested a need for standardisations of the personnel training to perform X-ray examinations according to ALARA principles.
    Matched MeSH terms: X-Rays
  9. Arora R, Bansal V, Buckchash H, Kumar R, Sahayasheela VJ, Narayanan N, et al.
    Phys Eng Sci Med, 2021 Dec;44(4):1257-1271.
    PMID: 34609703 DOI: 10.1007/s13246-021-01060-9
    According to the World Health Organization (WHO), novel coronavirus (COVID-19) is an infectious disease and has a significant social and economic impact. The main challenge in fighting against this disease is its scale. Due to the outbreak, medical facilities are under pressure due to case numbers. A quick diagnosis system is required to address these challenges. To this end, a stochastic deep learning model is proposed. The main idea is to constrain the deep-representations over a Gaussian prior to reinforce the discriminability in feature space. The model can work on chest X-ray or CT-scan images. It provides a fast diagnosis of COVID-19 and can scale seamlessly. The work presents a comprehensive evaluation of previously proposed approaches for X-ray based disease diagnosis. The approach works by learning a latent space over X-ray image distribution from the ensemble of state-of-the-art convolutional-nets, and then linearly regressing the predictions from an ensemble of classifiers which take the latent vector as input. We experimented with publicly available datasets having three classes: COVID-19, normal and pneumonia yielding an overall accuracy and AUC of 0.91 and 0.97, respectively. Moreover, for robust evaluation, experiments were performed on a large chest X-ray dataset to classify among Atelectasis, Effusion, Infiltration, Nodule, and Pneumonia classes. The results demonstrate that the proposed model has better understanding of the X-ray images which make the network more generic to be later used with other domains of medical image analysis.
    Matched MeSH terms: X-Rays
  10. Jothy SL, Saito T, Kanwar JR, Chen Y, Aziz A, Yin-Hui L, et al.
    Phys Med, 2016 Jan;32(1):150-61.
    PMID: 26526749 DOI: 10.1016/j.ejmp.2015.10.090
    The radioprotective effect of Polyalthia longifolia was studied in mice. P. longifolia treatment showed improvement in mice survival compared to 100% mortality in the irradiated mice. Significant increases in hemoglobin concentration, and red blood cell, white blood cell and platelet counts were observed in the animals pretreated with leaf extract. Pre-irradiation administration of P. longifolia leaf extract also increased the CFU counts of the spleen colony and increased the relative spleen size. A dose-dependent decrease in lipid peroxidation levels was observed in the animals pretreated with P. longifolia. However, although the animals pretreated with P. longifolia exhibited a significant increase in superoxide dismutase and catalase activity, the values remained below normal in both liver and the intestine. Pre-irradiation administration of P. longifolia also resulted in the regeneration of the mucosal crypts and villi of the intestine. Moreover, pretreatment with P. longifolia leaf extract also showed restoration of the normal liver cell structure and a significant reduction in the elevated levels of ALT, AST and bilirubin. These results suggested the radioprotective ability of P. longifolia leaf extract, which is significant for future investigation for human applications in developing efficient, economically viable, non-toxic natural and clinically acceptable novel radioprotectors.
    Matched MeSH terms: X-Rays
  11. Jamal AbuAlRoos N, Azman MN, Baharul Amin NA, Zainon R
    Phys Med, 2020 Oct;78:48-57.
    PMID: 32942196 DOI: 10.1016/j.ejmp.2020.08.017
    PURPOSE: The main objective of this study was to evaluate the efficacy of tungsten carbide as new lead-free radiation shielding material in nuclear medicine by evaluating the attenuation properties.

    MATERIALS AND METHODS: The elemental composition of tungsten carbide was analysed using Field-Emission Scanning Electron Microscopy (FESEM) with energy dispersive X-ray (EDX). The purity of tungsten carbide was 99.9%, APS: 40-50 µm. Three discs of tungsten carbide was fabricated with thickness of 0.1 cm, 0.5 cm and 1.0 cm. Three lead discs with similar thickness were used to compare the attenuation properties with tungsten carbide discs. Energy calibration of gamma spectroscopy was performed by using 123I, 133Ba, 152Eu, and 137Cs. Gamma radiation from these sources were irradiated on both materials at energies ranging from 0.160 MeV to 0.779 MeV. The experimental attenuation coefficients of lead and tungsten carbide were compared with theoretical attenuation coefficients of both materials from NIST database. The half value layer and mean free path of both materials were also evaluated in this study.

    RESULTS: This study found that the peaks obtained from gamma spectroscopy have linear relationship with all energies used in this study. The relative differences between the measured and theoretical mass attenuation coefficients are within 0.19-5.11% for both materials. Tungsten carbide has low half value layer and mean free path compared to lead for all thickness at different energies.

    CONCLUSION: This study shows that tungsten carbide has high potential to replace lead as new lead-free radiation shielding material in nuclear medicine.

    Matched MeSH terms: X-Rays
  12. Sammour RMF, Taher M, Chatterjee B, Shahiwala A, Mahmood S
    Pharmaceutics, 2019 Jul 18;11(7).
    PMID: 31323799 DOI: 10.3390/pharmaceutics11070350
    In the contemporary medical model world, the proniosomal system has been serving as a new drug delivery system that is considered to significantly enhance the bioavailability of drugs with low water solubility. The application of this system can improve the bioavailability of aceclofenac that is used for the relief of pain and inflammation in osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. The present study is intended to develop an optimized proniosomal aceclofenac formula by the use of different carriers. Aceclofenac proniosomes have been prepared by slurry method, and different carriers such as maltodextrin, mannitol, and glucose were tried. Prepared proniosomes characterized by differential scanning calorimetry (DSC) analysis and Fourier transform infrared (FTIR) analysis revealed the compatibility of the drug chosen with the ingredient added, powder X-ray diffractometry (XRD) confirmed the amorphous phase of the prepared proniosomes, and finally, the surfactant layer was observed by scanning electron microscopy (SEM). Aceclofenac physical state transformations were confirmed with all formulas but maltodextrin proniosomes exhibited solubility more than other formulations. HPLC method has been used to analyze the niosomes derived from proniosomes in terms of their entrapment capability and drug content. The obtained results revealed that aceclofenac proniosomes can be successfully prepared by using different carriers.
    Matched MeSH terms: X-Rays
  13. Wong YH, Tan HY, Kasbollah A, Abdullah BJJ, Yeong CH
    Pharmaceutics, 2019 Nov 12;11(11).
    PMID: 31718079 DOI: 10.3390/pharmaceutics11110596
    INTRODUCTION: Transarterial radioembolization (TARE) has been proven as an effective treatment for unresectable liver tumor. In this study, neutron activated, 153Sm-labeled microspheres were developed as an alternative to 90Y-labeled microspheres for hepatic radioembolization. 153Sm has a theranostic advantage as it emits both therapeutic beta and diagnostic gamma radiations simultaneously, in comparison to the pure beta emitter, 90Y.

    METHODS: Negatively charged acrylic microspheres were labeled with 152Sm ions through electrostatic interactions. In another formulation, the Sm-labeled microsphere was treated with sodium carbonate solution to form the insoluble 152Sm carbonate (152SmC) salt within the porous structures of the microspheres. Both formulations were neutron-activated in a research reactor. Physicochemical characterization, gamma spectrometry, and radiolabel stability tests were carried out to study the performance and stability of the microspheres.

    RESULTS: The Sm- and SmC-labeled microspheres remained spherical and smooth, with a mean size of 35 µm before and after neutron activation. Fourier transform infrared (FTIR) spectroscopy indicated that the functional groups of the microspheres remained unaffected after neutron activation. The 153Sm- and 153SmC-labeled microspheres achieved activity of 2.53 ± 0.08 and 2.40 ± 0.13 GBq·g-1, respectively, immediate after 6 h neutron activation in the neutron flux of 2.0 × 1012 n·cm-2·s-1. Energy-dispersive X-ray (EDX) and gamma spectrometry showed that no elemental and radioactive impurities were present in the microspheres after neutron activation. The retention efficiency of 153Sm in the 153SmC-labeled microspheres was excellent (~99% in distilled water and saline; ~97% in human blood plasma), which was higher than the 153Sm-labeled microspheres (~95% and ~85%, respectively).

    CONCLUSION: 153SmC-labeled microspheres have demonstrated excellent properties for potential application as theranostic agents for hepatic radioembolization.

    Matched MeSH terms: X-Rays
  14. Salih, A.M., Wan Md. Zin Wan Yunus, Khairul Zaman Mohd Dahlan, Mohd Hilmi Mahmood, Mansor Ahmad
    MyJurnal
    Synthesis of palm oil based-urethane acrylate (POBUA) resins was carried out by acrylation of epoxidizedpalm oil (EPOP) using acrylic acid in the presence of a catalyst and followed by isocyanation to obtainthe POBUA. Using the monomer as a diluent in the formulation, 4% of photoinitiator and incorporationof organoclay (1-5% wt), nanocomposites were obtained upon UV irradiation. The X-ray DiffractoryXRD study revealed that the nanocomposites obtained were of the exfoliation type. The presence ofthe clay improved the hardness and did not affect the thermal stability. Similarly, it increased the glasstransition temperature Tg but reduced the modulus as the clay content was increased. The improvementof the tensile strength was only obtained when the clay concentration was 5 phr.
    Matched MeSH terms: X-Rays
  15. Nur Aqilah Zainal, Shariff Ibrahim, Borhannuddin Arifin
    MyJurnal
    An agricultural waste, the cocoa pod husk was chemically modified using a dehydrating agent, zinc chloride (ZnCl2), carbonised and used for the remediation of acid dyes in an aqueous solution. The targeted acid dyes are: (i) Acid Violet 17 (AV17); (ii) Acid Yellow 36 (AY36); and (iii) Acid Blue 29 (AB29). The physicochemical properties of the zinc chloride-modified cocoa pod husk-based carbon (ZCPHC) were characterised by ash content, bulk density, pH slurry, pHpzc and Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray (EDX) analysis. The bulk density and ash content of the prepared carbon is 0.55 g cm-1 and 7.0% respectively. The photograph of SEM shows distinct changes at the ZCPHC carbon surface as it has large pores formed due to ZnCl2 modification. The adsorption tests were performed in a batch adsorption system using an aqueous solution of the understudy acid dyes. The influence of pH and dose of an adsorbent on the acid dye uptake was investigated and discussed. The adsorption was in favour at acidic condition with maximum removal observed at pH 2. The removal efficiency of the aqueous acid dye solution increased with the increase in adsorbent dosage. The kinetic experiment showed equilibrium time is less than 40 minutes and the kinetic data for all three understudy acid dyes fitted well with the pseudo-second-order model with a correlation coefficient (R2) values above 0.98.
    Matched MeSH terms: X-Rays
  16. Chiroma H, Ezugwu AE, Jauro F, Al-Garadi MA, Abdullahi IN, Shuib L
    PeerJ Comput Sci, 2020;6:e313.
    PMID: 33816964 DOI: 10.7717/peerj-cs.313
    Background and Objective: The COVID-19 pandemic has caused severe mortality across the globe, with the USA as the current epicenter of the COVID-19 epidemic even though the initial outbreak was in Wuhan, China. Many studies successfully applied machine learning to fight COVID-19 pandemic from a different perspective. To the best of the authors' knowledge, no comprehensive survey with bibliometric analysis has been conducted yet on the adoption of machine learning to fight COVID-19. Therefore, the main goal of this study is to bridge this gap by carrying out an in-depth survey with bibliometric analysis on the adoption of machine learning-based technologies to fight COVID-19 pandemic from a different perspective, including an extensive systematic literature review and bibliometric analysis.

    Methods: We applied a literature survey methodology to retrieved data from academic databases and subsequently employed a bibliometric technique to analyze the accessed records. Besides, the concise summary, sources of COVID-19 datasets, taxonomy, synthesis and analysis are presented in this study. It was found that the Convolutional Neural Network (CNN) is mainly utilized in developing COVID-19 diagnosis and prognosis tools, mostly from chest X-ray and chest CT scan images. Similarly, in this study, we performed a bibliometric analysis of machine learning-based COVID-19 related publications in the Scopus and Web of Science citation indexes. Finally, we propose a new perspective for solving the challenges identified as direction for future research. We believe the survey with bibliometric analysis can help researchers easily detect areas that require further development and identify potential collaborators.

    Results: The findings of the analysis presented in this article reveal that machine learning-based COVID-19 diagnose tools received the most considerable attention from researchers. Specifically, the analyses of results show that energy and resources are more dispenses towards COVID-19 automated diagnose tools while COVID-19 drugs and vaccine development remains grossly underexploited. Besides, the machine learning-based algorithm that is predominantly utilized by researchers in developing the diagnostic tool is CNN mainly from X-rays and CT scan images.

    Conclusions: The challenges hindering practical work on the application of machine learning-based technologies to fight COVID-19 and new perspective to solve the identified problems are presented in this article. Furthermore, we believed that the presented survey with bibliometric analysis could make it easier for researchers to identify areas that need further development and possibly identify potential collaborators at author, country and institutional level, with the overall aim of furthering research in the focused area of machine learning application to disease control.

    Matched MeSH terms: X-Rays
  17. Kunaparaju K, Shetty K, Jathanna V, Nath K, M R
    Patient Saf Surg, 2021 Jan 05;15(1):1.
    PMID: 33402200 DOI: 10.1186/s13037-020-00273-3
    BACKGROUND: Accidental ingestion of a dental bur during the dental procedure is a rare, but a potentially serious complication. Early recognition and foreign body retrieval is essential to prevent adverse patient outcomes.

    CASE PRESENTATION: A 76-year old male patient, presented to the department with a chief complaint of sensitivity in his upper right back tooth due to attrition. After assessing the pulp status, root canal therapy was planned for the tooth. During the procedure, it was noticed that the dental bur slipped out of the hand piece and the patient had accidentally ingested it. The patient was conscious and had no trouble while breathing at the time of ingestion of the bur although he had mild cough which lasted for a short duration. The dental procedure was aborted immediately and the patient was taken to the hospital for emergency care. The presence and location of the dental bur was confirmed using chest and abdominal x-rays and it was subsequently retrieved by esophagogastroduodenoscopy (EGD) procedure under general anaesthesia on the same day as a part of the emergency procedure. The analysis of this case reaffirms the importance of the use of physical barriers such as rubber dams and gauze screens as precautionary measures to prevent such incidents from occurring.

    CONCLUSION: Ingestion of instruments are uncertain and hazardous complications to encounter during a dental procedure. The need for physical barrier like rubber dam is mandatory for all dental procedures. However, the dentist should be well trained to handle such medical emergencies and reassure the patient by taking them into confidence. Each incident encountered should be thoroughly documented to supply adequate guidance for treatment aspects. This would fulfil the professional responsibilities of the dentist/ clinician and may help avoid possible legal and ethical issues. This case report emphasizes on the need for the usage of physical barriers during dental procedures in order to avoid medical emergencies.

    Matched MeSH terms: X-Rays
  18. Choo YSL, Giamberini M, Antonio J, Waddell PG, Benniston AC
    Org Biomol Chem, 2020 Nov 04;18(42):8735-8745.
    PMID: 33094783 DOI: 10.1039/d0ob01533d
    The reaction of diethyl 2,5-bis(tert-butyl)phenoxy-3,6-dihydroxyterephthalate (1) with tetraethylene glycol di(p-toluenesulfonate) under high-dilution conditions afforded several isolated products. Two products were identified as macrocycles with one being the 1 + 1 crown ether derivative 3 (10% yield), and the second being the 2 + 2 crown ether compound D3 (19% yield). The X-ray structure for 3 was determined with the asymmetric unit observed to comprise half of the molecule. The small crown ether ring of 3 interacts with K+ or H+ ions in MeOH, but binding is weak and the macrocyclic cavity is too small to fully encapsulate the K+ ion. Transesterification of compounds 1, its methylated version 2 and 3 with diols such as ethylene glycol or 1,4-butandiol produced monomers (M1-M3) which were reacted with terephthaloyl chloride. Short oligomers were produced (PolyM1-PolyM3) rather than extensive polymeric materials and all displayed solid state fluorescence. The absorption and fluorescence properties of M1-M2 and their polymers can be related to subtle structural changes. The Stokes shift for M2 of 15 627 cm-1 in DCM is one of the largest observed for a simple organic chromophore in fluid solution.
    Matched MeSH terms: X-Rays
  19. Payus AO, Rajah R, Febriany DC, Mustafa N
    Open Access Maced J Med Sci, 2019 Feb 15;7(3):396-399.
    PMID: 30834009 DOI: 10.3889/oamjms.2019.114
    BACKGROUND: De novo pulmonary embolism (DNPE) is a term used when pulmonary embolism (PE) occur in the absence of deep vein thrombosis (DVT). Most DNPE cases occur in a patient who had a recent injury to the chest.

    CASE PRESENTATION: However, here we report a case of DNPE with a slightly different presentation where there is no preceding trauma and has symptoms that mimic severe pneumonia. He presented with high fever, dyspnoea and pleuritic chest pain. Despite on 10 L of oxygen supplementation via high flow mask and already given bolus intravenous antibiotic, the patient still tachypnoeic and was persistently in type I respiratory failure. His chest X-ray showed consolidative changes. Upon further investigation revealed no evidence of DVT on Doppler ultrasound and normal D-dimer level. Due to the high index of suspicion by the attending physician, PE was suspected and later confirmed with computed tomography pulmonary angiography scan. He was successfully treated with anticoagulation therapy. The objective of this case report is to share the difficult experience of diagnosing PE when the presentation highly atypical and mimics severe pneumonia.

    CONCLUSION: And with such a masquerading presentation, one can easily miss the diagnosis. To the best of our knowledge, there are very few similar cases reported.

    Matched MeSH terms: X-Rays
  20. Lin R, Hu E, Liu M, Wang Y, Cheng H, Wu J, et al.
    Nat Commun, 2019 04 09;10(1):1650.
    PMID: 30967531 DOI: 10.1038/s41467-019-09248-0
    Despite the importance of studying the instability of delithiated cathode materials, it remains difficult to underpin the degradation mechanism of lithium-rich cathode materials due to the complication of combined chemical and structural evolutions. Herein, we use state-of-the-art electron microscopy tools, in conjunction with synchrotron X-ray techniques and first-principle calculations to study a 4d-element-containing compound, Li2Ru0.5Mn0.5O3. We find surprisingly, after cycling, ruthenium segregates out as metallic nanoclusters on the reconstructed surface. Our calculations show that the unexpected ruthenium metal segregation is due to its thermodynamic insolubility in the oxygen deprived surface. This insolubility can disrupt the reconstructed surface, which explains the formation of a porous structure in this material. This work reveals the importance of studying the thermodynamic stability of the reconstructed film on the cathode materials and offers a theoretical guidance for choosing manganese substituting elements in lithium-rich as well as stoichiometric layer-layer compounds for stabilizing the cathode surface.
    Matched MeSH terms: X-Rays
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