The Use of Biomaterials in Internal Radiation Therapy

Radiotherapy has become one of the most prominent and effective modalities for cancer treatment and care. Ionising radiation, delivered either from external or internal sources, can be targeted to cancerous cells causing damage to DNA that can induce apoptosis. External beam radiotherapy delivers either photon radiation (x-rays or gamma rays) or particle radiation (neutrons or protons) in a targeted manner to specific tumour locations. Internal radiotherapy involves placing radioactive sources within the body to deliver localised doses of therapeutic radiation to tumours using short range radionuclides. Biomaterials have been developed to allow more precise targeting of radiotherapy in order to reduce toxicity to surrounding healthy tissues and increase treatment efficacy. These unique biomaterials have been developed from polymers, glasses and ceramics. Polymeric materials have been used to both displace healthy tissue from tumours receiving radiation, and to deliver radioactive sources into the body. These polymers can respond to various stimuli, such as radiation or reactive oxygen species, to deliver therapeutic payloads to target tissue during or post radiotherapy. Glass-based biomaterials doped with radionuclides have also been developed to provide in situ radiotherapy. Novel biomaterials that can enhance the synergistic effect of other treatment modalities, such as chemotherapy and immunotherapy, continue to be developed. Theranostic materials that are capable of providing diagnostic information whilst simultaneously delivering a therapeutic effect to enhance radiotherapy are also briefly reviewed

Acoustic metamaterials for sound absorption and insulation in buildings

© 2024 The Authors. Published by Elsevier. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.buildenv.2024.111250Despite the emergence of acoustic metamaterials with superior sound absorption and transmission loss, their adoption for building sound insulation has been limited. Sound insulation design in buildings is still informed by the acoustic performance of conventional materials, where the mass law contradicts light weighting when it comes to acoustic design. In any case buildings close to noisy environments such as motorways, railway lines and airports still suffer from significant low frequency noise pollution. Although the limited working bandwidth of acoustic metamaterials is a major issue limiting its application, combining meta-units that interact at various frequencies alongside multi-layer conventional solutions can deliver superior sound insulation in buildings. The review put forwards acoustic metamaterials, specifically emphasising superior sound absorption and transmission/insertion loss as critical properties for effective building sound insulation. The paper reveals a variety of acoustic metamaterials that can be adopted to compliment conventional sound insulation approaches for acoustically efficient building design. The performance of these metamaterials is then explained through their characteristic negative mass density, bulk modulus or repeating or locally resonating microstructure. The review is also extended to air transparent acoustic metamaterials that can be used for sound insulation of building ventilation. Lastly the prospects and challenges regarding the adoption of acoustic metamaterials in building insulation are also discussed. Overall, tuneable, and multifunctional acoustic metamaterials when thoughtfully integrated to building sound insulation can lead to significant acoustic comfort, space-saving and light-weighting.Published versio

Melt Pool Monitoring and X-ray Computed Tomography-Informed Characterisation of Laser Powder Bed Additively Manufactured Silver–Diamond Composites

In this study, silver (Ag) and silver–diamond (Ag-D) composites with varying diamond (D) content are fabricated using laser powder bed fusion (L-PBF) additive manufacturing (AM). The L-PBF process parameters and inert gas flow rate are optimised to control the build environment and the laser energy density at the powder bed to enable the manufacture of Ag-D composites with 0.1%, 0.2% and 0.3% D content. The Ag and D powder morphology are characterised using scanning electron microscopy (SEM). Ag, Ag-D0.1%, Ag-D0.2% and Ag-D0.3% tensile samples are manufactured to assess the resultant density and tensile strength. In-process EOSTATE melt pool monitoring technology is utilised as a comparative tool to assess the density variations. This technique uses in-process melt pool detection to identify variations in the melt pool characteristics and potential defects and/or density deviations. The resultant morphology and associated defect distribution for each of the samples are characterised and reported using X-ray computed tomography (xCT) and 3D visualisation techniques. Young’s modulus, the failure strain and the ultimate tensile strength of the L-PBF Ag and Ag-D are reported. The melt pool monitoring results revealed in-process variations in the build direction, which was confirmed through xCT 3D visualisations. Additionally, the xCT analysis displayed density variations for all the Ag-D composites manufactured. The tensile results revealed that increasing the diamond content reduced Young’s modulus and the ultimate tensile strength

Acromegaly Presenting as Cardiac Failure - A Case Report

Acromegaly is characterized by chronic hypersecretion of growth hormone (GH) and is associated with increased mortality rate because of the potential complications such as cardiovascular disease, respiratory disease, or malignancy, which are probably caused by the long-term exposure of tissues to excess GH, for at least 10 years, before diagnosis and treatment. Here we are reporting a case of acromegaly who initially presented with features of left ventricular failure for which she got herself admitted in CCU and was treated conservatively. Later on, after clinical examination and investigations she was diagnosed as a case of mitral regurgitation due to cardiomyopathy caused by acromegaly. After the successful transsphenoidal resection of the pituitary microadenoma, the level of GH was normalized and heart failure improved. Key words: acromegaly; heart failure; Pituitary microadenoma. DOI: http://dx.doi.org/10.3329/bsmmuj.v4i2.8644 BSMMU J 2011; 4(2):122-12

Yttrium doped phosphate-based glasses: structural and degradation analyses

This study investigates the role of yttrium in phosphate-based glasses in the system 45(P 2 O 5)-25(CaO)-(30-x)(Na 2 O)-x(Y 2 O 3) (0≤ x≤ 5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spec-troscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31 P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y 2 O 3 content as metaphosphate units (Q 2) decreased with subsequent increase in pyrophosphate species (Q 1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crys-tallised glass samples revealed the presence of calcium pyrophosphate (Ca 2 P 2 O 7) and sodium metaphosphate (NaPO 3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y 2 O 3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y 2 O 3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yt-trium (YO 6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles

Developments and prospects of additive manufacturing for thermoelectric materials and technologies

© 2024 The Authors. Published by Elsevier B.V. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.susmat.2024.e01008In view of the increased demand for electricity and the associated environmental and financial concerns, there is an urgent need to develop technological solutions that can improve the efficiency of engineering systems and processes. Thermoelectric (TE) technologies, with their capability of direct conversion of thermal energy into electrical energy, are promising technologies for green power generation through using them as energy harvesting devices for waste heat recovery in industrial processes and power generation systems. To date, TE technologies are still not commercialized on a large scale due to various economic and technical obstacles. The majority of previous research on TE technologies concentrated on improving the TE properties, such as electronic transport and figure-of-merit, while limited attempts were made to identify the best material processing techniques or reduce the cost of manufacturing. Conventional Manufacturing (CM) of TE materials and devices is multi-stage, complex, labour-intensive, time-consuming, and has high energy requirements. Thus, manufacturing challenges are considered key contributors toward limited industrial adoption of TE technologies. The rapid advent of advanced Additive Manufacturing (AM) processes, in recent years, caused dramatic changes in engineering design thinking and created opportunities to solve manufacturing challenges. With its significant capabilities, AM can be the route to address the shortcomings of CM of the thermoelectric technologies. In this regard, this paper presents an in-depth review of the literature studies on using AM technologies, such as selective laser melting, fused deposition modelling, direct ink writing, stereo lithography, etc., for manufacturing TE materials and devices. The benefits and challenges of each AM technology are discussed to identify their merits and the required future research. This paper demonstrates the role of AM in advancing green materials and technologies for solving some of the outstanding energy and environmental issues.Accepted versio

Spectrum of thyroid dysfunctions among hospitalized patients with non-critically ill coronavirus disease 2019: A cross-sectional study

Background: Patients with coronavirus disease 2019 (COVID-19) particularly critically ill ones may present with different types of thyroid abnormalities. However, data regarding thyroid function tests (TFTs) among noncritical patients with COVID-19 are scarce. This study aimed to assess thyroid functions and their associations with the severity of illness among non-critically ill hospitalized patients with COVID-19. Methods: This cross-sectional study assessed TFTs in 87 (aged 18-65 years) RT-PCR-confirmed COVID-19 patients admitted to a tertiary-care hospital in Bangladesh. Diagnosis of non–critical illness and severity (mild, moderate, and severe) were defined by WHO’s interim guidance. Patients having known thyroid dysfunctions or taking drugs that may affect thyroid functions were excluded from the study. Serum TSH, FT4, and FT3 were measured by chemiluminescent immunoassay. Results: Majority of the patients (72%) had normal thyroid function. Among the abnormalities, the highest frequency was isolated hyperthyroxinemia (12.6%) and the rest were subclinical hypothyroidism (6.9%), subclinical thyrotoxicosis (4.6%), thyrotoxicosis (2.3%), isolated tri-iodothyroninemia (1.1%), and hypothyroidism (1.1%).  Serum TSH, FT4, and FT3 levels were similar across the spectrum of noncritical illness. No significant correlation was found between the inflammatory markers (C-reactive protein, ferritin, and D-dimer) and TSH levels. Conclusions: More than one-fourth of non-critically ill hospitalized patients with COVID-19 presented with a spectrum of thyroid abnormalities with isolated hyperthyroxinemia being the most common. However, TFTs had no significant associations with the severity of illness among noncritically ill patients with COVID-19. Bangabandhu Sheikh Mujib Medical University Journal 2023;16(2): 81-86

Thermal and crystallization kinetics of yttrium-doped phosphate-based glasses

© 2019 The American Ceramic Society and Wiley Periodicals, Inc Yttrium-doped glasses have been utilized for biomedical applications such as radiotherapy, especially for liver cancer treatment. In this paper, the crystallization behavior of phosphate-based glasses doped with yttrium (in the system 45P2O5–(30 − x) Na2O–25CaO–xY2O3—where x = 0, 1, 3 and 5) have been investigated via Differential Scanning Calorimetry (DSC) using nonisothermal technique at different heating rates (5°C, 10°C, 15°C and 20°C/min). The glass compositions were characterized via EDX, XRD, Density and Molar volume analysis. The Moynihan and Kissinger methods were used for the determination of glass transition activation energy (Eg) which decreased from 192 to 118 kJ/mol (Moynihan) and 183 to 113 kJ/mol (Kissinger) with increasing yttrium oxide content. Incorporation of 0 to 5 mol% Y2O3 revealed an approximate decrease of 71 kJ/mol (Ozawa and Augis) for onset crystallization (Ex) and 26 kJ/mol (Kissinger) for crystallization peak activation energies (Ec). Avrami index (n) value analyzed via Matusita–Sakka equation suggested a one-dimensional crystal growth for the glasses investigated. SEM analysis explored the crystalline morphologies and revealed one-dimensional needle-like crystals. Overall, it was found that these glass formulations remained amorphous with up to 5 mol% Y2O3 addition with further increases in Y2O3 content resulting in significant crystallization

Development of yttrium phosphate based porous microspheres for radioembolisation therapy

The principal focus for the materials developed in this thesis was for Radioembolisation therapy applications, particularly tailoring phosphate based glasses (PBG’s) formulations for the treatment of liver cancer. PBG’s have been widely considered in this study due to their fully resorbable, controlled degradation rates and biocompatible properties. Microspheres are gaining attraction as possible advanced materials, owing to their advantages over irregular shaped particles due to its better size, shape, higher surface area and improved flow characteristics. Phosphate glass microspheres containing yttrium oxide (Y2O3) are an area of particular interest in this thesis as Y2O3 has short half-life and been shown to significantly be efficient for improving chemical durability, which in turn is highly beneficial for selective internal radiation therapy (SIRT). Initially, this study investigate the role of yttrium in phosphate-based glasses in the system of 45P2O5–25CaO–(30-x)Na2O–xY2O3 (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation profiles. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses. 31P NMR analysis confirmed that depolymerisation of the phosphate network occurred which increased with Y2O3 content as metaphosphate units (Q2) decreased with subsequent increase in pyrophosphate species (Q1). The NMR results correlated well with structural changes observed via FTIR, Raman and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca2P2O7) and sodium metaphosphate (NaPO3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations comprising 3 and 5 mol% Y2O3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y2O3 content. The reduction in degradation rate was ascribed to the creation of Y-O-P bonds, which resulted from the octahedral structure of yttrium (YO6) cross-linking phosphate chains, subsequently increasing the chemical durability of the glasses. The ion release profiles also correlated well with degradation profiles. This study also showed successful manufacture of both solid (SGMS) and porous (PGMS) yttrium containing phosphate glass microspheres via flame spheroidisation process within the specific size range 25-45 μm through the modification and optimisation of the manufacturing process. A modified powder feeding and collection system was designed to improve the yield of smaller size range microspheres (in terms of sphericity). Various flow rates of oxygen/acetylene gas, particle to porogen ratio, effect of acid wash, position of the flame were investigated to obtain the maximum yield of smaller sized porous microsphere production. Microspheres generated with higher flow rate (3:3) at 1:0.5 ratio (glass particles: CaCO3) with 5M acetic acid wash were used for the preparation of smaller size porous microspheres based on the findings of the pore distribution, number of pores and sphericity. NMR analysis of SGMS and PGMS indicated that increasing trend of Q1 species (from 35% to 53% for SGMS and 48% to 61% for PGMS) were found with increasing Y2O3 concentration from 0 to 5 mol%, whereas Q2 species decreased from 64 to 47 percent for SGMS and 42 to 29 percent for PGMS. Moreover, a limited amount of Q0 species were found in all of the formulations studied for PGMS. In addition, the dissolution rates of the porous microsphere were higher than the solid microspheres for all glass formulations which were ascribed to the difference in the surface area and porosity between porous and solid microspheres. This study also revealed that the glass formulations remained amorphous with up to 5 mol% Y2O3 addition with further increases in Y2O3 content resulting in significant crystallisation. This phenomenon has been explained by activation energy and crystallisation kinetics of 0 to 5 mol% yttrium containing phosphate based glasses and investigated via Differential Scanning Calorimetry (DSC) using non-isothermal technique at different heating rates (5°C, 10°C, 15°C and 20°C/min). The Moynihan and Kissinger methods were used for the determination of glass transition activation energy (Eg) which decreased from 192 kJ/mol to 118 kJ/mol (Moynihan) and 183 kJ/mol to 113 kJ/mol (Kissinger) with increasing yttrium oxide content. Incorporation of 0 to 5 mol% Y2O3 revealed an approximate decrease of 71 kJ/mol (Ozawa and Augis) for onset crystallisation (Ex) and 26 kJ/mol (Kissinger) for crystallisation peak activation energies (Ec). Avrami index (n) value analysed via Matusita-Sakka equation suggested a one-dimensional crystal growth for the glasses investigated. SEM analysis explored the crystalline morphologies and revealed one-dimensional needle-like crystals. In order to produce porous phosphate microspheres with high yttrium content, a new approach and manufacturing technique was devised in this study in further. In this alternative manufacturing process, different phosphate based glass formulations were mixed with Y2O3 particles at different percentage ratios and fed into the flame. Microspheres of P55-60Y40 (mixture of 60% P55 glass formulations + 40% Y2O3 particles) and P60-60Y40 (mixture of 60% P60 glass formulations + 40% Y2O3 particles) were considered as optimum combinations and ratios as these combinations achieved desired Y2O3 (above 17 mol%) and P2O5 contents (40 mol% or more) confirmed via EDX analysis. XRD analysis revealed that glass-ceramic was formed for high yttrium containing phosphate microspheres instead of glass microspheres. Dissolution profiles of glass-ceramics showed that the higher decrease in particle size was observed for porous glass-ceramic microspheres (PGCMS) in comparison to their respective solid glass-ceramic microspheres (SGCMS). Finally, this study demonstrated successful loading of anticancer drug Doxorubicin (DOX) inside the high yttrium containing porous phosphate glass-ceramic microspheres (P60YPGCMS) via optimisation of drug encapsulation processes. DOX encapsulated microspheres showed a comparatively controlled release behaviour of DOX at low concentrations (2.5 mg/ml) compared to high concentrations (25 mg/ml)