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result(s) for
"Lau, Kenneth"
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Radiological correlates of vocal fold bowing as markers of Parkinson’s disease progression: A cross-sectional study utilizing dynamic laryngeal CT
by
Lau, Kenneth K.
,
Ma, Andrew
,
Thyagarajan, Dominic
in
Analysis
,
Biological markers
,
Biology and Life Sciences
2021
To determine whether arytenoid cartilage position and dynamics change with advancing duration and severity (as graded by MDS-UPDRS part III scores) in Parkinson's disease, in a cross-sectional study design, we performed laryngeal four-dimensional computed tomography (4D-CT) in people with Parkinson's disease and controls. 31 people with Parkinson's disease covering a range of disease duration and severity and 19 controls underwent laryngeal 4D-CT whilst repeatedly vocalizing. We measured on each CT volume the glottic area (GA), inter-arytenoid distance (IAD), IAD-Area index (IAI) and arytenoid cartilage velocity (av[right arrow]). People with Parkinson's disease had reductions in the mean/effective minimum IAD when compared to controls, while mean/effective minimum GA and mean/effective maximum IAI were increased. Arytenoid cartilage velocities showed no difference. On Spearman correlation analyses, advancing disease duration and severity of PD showed moderately strong and significant correlations with increasing mean/effective minimum GA, increasing mean/effective maximum IAI and decreasing effective minimum IAD. Linear mixed models which considered the effects of intra and inter-individual variation showed that both disease duration (b = -0.011, SEb = 0.053, 95% CI [-0.022, 0], t(27) = -2.10, p = 0.045) and severity (b = -0.069, SEb = 0.032, 95% CI [-0.14,-0.0039], t(27) = -2.17, p = 0.039) were significant predictors for IAD, and also for transformed values of the GA and IAI. There are progressive alterations in phonatory posturing as Parkinson's disease advances. The increases in GA despite reductions in IAD are concordant with prior observations of vocal fold bowing. Our study provides a basis for using laryngeal 4D-CT to assess disease progression in Parkinson's disease.
Journal Article
Building ultraconformal protective layers on both secondary and primary particles of layered lithium transition metal oxide cathodes
2019
Despite their relatively high capacity, layered lithium transition metal oxides suffer from crystal and interfacial structural instability under aggressive electrochemical and thermal driving forces, leading to rapid performance degradation and severe safety concerns. Here we report a transformative approach using an oxidative chemical vapour deposition technique to build a protective conductive polymer (poly(3,4-ethylenedioxythiophene)) skin on layered oxide cathode materials. The ultraconformal poly(3,4-ethylenedioxythiophene) skin facilitates the transport of lithium ions and electrons, significantly suppresses the undesired layered to spinel/rock-salt phase transformation and the associated oxygen loss, mitigates intergranular and intragranular mechanical cracking, and effectively stabilizes the cathode–electrolyte interface. This approach remarkably enhances the capacity and thermal stability under high-voltage operation. Building a protective skin at both secondary and primary particle levels of layered oxides offers a promising design strategy for Ni-rich cathodes towards high-energy, long-life and safe lithium-ion batteries.
Intensive research efforts are underway to enable applications of layered lithium transition metal oxides in batteries. Here the authors report an oxidative chemical vapour deposition technique to conformally coat both the primary and the secondary particles of these oxides to unleash potential applications.
Journal Article
Oxidative chemical vapor deposition of polyaniline thin films
2017
Polyaniline (PANI) is synthesized via oxidative chemical vapor deposition (oCVD) using aniline as monomer and antimony pentachloride as oxidant. Microscopy and spectroscopy indicate that oCVD processing conditions influence the PANI film chemistry, oxidation, and doping level. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) indicate that a substrate temperature of 90 °C is needed to minimize the formation of oligomers during polymerization. Lower substrate temperatures, such as 25 °C, lead to a film that mostly includes oligomers. Increasing the oxidant flowrate to nearly match the monomer flowrate favors the deposition of PANI in the emeraldine state, and varying the oxidant flowrate can directly influence the oxidation state of PANI. Changing the reactor pressure from 700 to 35 mTorr does not have a significant effect on the deposited film chemistry, indicating that the oCVD PANI process is not concentration dependent. This work shows that oCVD can be used for depositing PANI and for effectively controlling the chemical state of PANI.
Journal Article
Enhancing Hybrid Solar Cell Performance with Conducting Polymer Thin Films Deposited by Oxidative Chemical Vapor Deposition
by
Li, Guancheng
,
Opila, Robert L.
,
Prasath, Varun S.
in
Chemical vapor deposition
,
Conductivity
,
Dielectric films
2025
Hybrid solar cells, which combine inorganic and organic materials, offer a promising pathway to achieve low cost, flexible, high-performance photovoltaic devices. This work explores the application of oxidative chemical vapor deposition (oCVD) to deposit poly(3,4-ethylenedioxythiophene) (PEDOT) as a transparent hole transfer layer in hybrid solar cells. Unlike solution-processed PEDOT with polystyrene sulfonate solubilizer (PEDOT:PSS), oCVD allows for growing high-purity PEDOT that provides conformal coverage on textured substrates, enabling enhanced antireflective effects and improved charge extraction. We discuss the advantages of oCVD PEDOT in hybrid architecture, its compatibility with textured substrates, and its potential to achieve higher efficiency.
Journal Article
Polarization screening-induced magnetic phase gradients at complex oxide interfaces
by
Balachandran, Prasanna V.
,
Ramasse, Quentin M.
,
Nejati, Siamak
in
140/146
,
639/301/119/2795
,
639/301/119/544
2015
Thin-film oxide heterostructures show great potential for use in spintronic memories, where electronic charge and spin are coupled to transport information. Here we use a La
0.7
Sr
0.3
MnO
3
(LSMO)/PbZr
0.2
Ti
0.8
O
3
(PZT) model system to explore how local variations in electronic and magnetic phases mediate this coupling. We present direct, local measurements of valence, ferroelectric polarization and magnetization, from which we map the phases at the LSMO/PZT interface. We combine these experimental results with electronic structure calculations to elucidate the microscopic interactions governing the interfacial response of this system. We observe a magnetic asymmetry at the LSMO/PZT interface that depends on the local PZT polarization and gives rise to gradients in local magnetic moments; this is associated with a metal–insulator transition at the interface, which results in significantly different charge-transfer screening lengths. This study establishes a framework to understand the fundamental asymmetries of magnetoelectric coupling in oxide heterostructures.
The interface between magnetic and ferroelectric thin-film materials offers the opportunity to couple these important properties. Here, the authors combine experimental and theoretical studies into a model interface to investigate the details of how electron charges and spins evolve across this interface.
Journal Article
Automated measurement of inter-arytenoid distance on 4D laryngeal CT: A validation study
by
Desai, Nandakishor
,
Palaniswami, Marimuthu
,
Lau, Kenneth K.
in
Arytenoid Cartilage - diagnostic imaging
,
Automation
,
Bias
2023
Changes to the voice are prevalent and occur early in Parkinson’s disease. Correlates of these voice changes on four-dimensional laryngeal computed-tomography imaging, such as the inter-arytenoid distance, are promising biomarkers of the disease’s presence and severity. However, manual measurement of the inter-arytenoid distance is a laborious process, limiting its feasibility in large-scale research and clinical settings. Automated methods of measurement provide a solution. Here, we present a machine-learning module which determines the inter-arytenoid distance in an automated manner. We obtained automated inter-arytenoid distance readings on imaging from participants with Parkinson’s disease as well as healthy controls, and then validated these against manually derived estimates. On a modified Bland-Altman analysis, we found a mean bias of 1.52 mm (95% limits of agreement -1.7 to 4.7 mm) between the automated and manual techniques, which improves to a mean bias of 0.52 mm (95% limits of agreement -1.9 to 2.9 mm) when variability due to differences in slice selection between the automated and manual methods are removed. Our results demonstrate that estimates of the inter-arytenoid distance with our automated machine-learning module are accurate, and represents a promising tool to be utilized in future work studying the laryngeal changes in Parkinson’s disease.
Journal Article
Prevalence of SIRS with primary epiploic appendagitis
2024
PurposePrimary epiploic appendagitis (PEA) is not an uncommon cause of abdominal pain. The systemic inflammatory response syndrome (SIRS) criteria have high sensitivity for early detection of inflammation and infection. To date, there is limited data about the association between SIRS and PEA. The aims of this retrospective study were to evaluate the prevalence of SIRS response and its clinical relevance in patients diagnosed with PEA within a large tertiary hospital network.MethodsA retrospective study was performed on all consecutive adult patients who presented to four major emergency departments with CT-confirmed PEA from 01 January 2022 to 27 March 2023. The fulfilment of SIRS criteria, hospital admission rate and treatments provided were analysed for these patients.ResultsSeventy-three patients had CT-confirmed PEA. Seventeen patients (23.2%) with PEA were SIRS positive. The hospital admission rate in the SIRS group trended higher than the non-SIRS group (odds ratio of 2.51, 95% CI (0.75, 8.39)). The odds of having an associated radiological comorbidity unrelated to PEA were 18.7 times higher in the SIRS positive group. Fifty-seven (78%) patients were discharged home, and 16 (22%) patients were admitted into hospital. Nearly all patients were treated conservatively (98.6%).ConclusionPEA patients with SIRS response trend towards a higher hospital admission rate and are significantly more likely to have other radiological comorbidities than non-SIRS patients. It is important to look for other pathological conditions in a SIRS positive patient with a CT-diagnosis of PEA.
Journal Article
High-pitched tin-filtered CT pulmonary angiography in radiation dose reduction for pulmonary embolism investigations in young females
2023
IntroductionComputed tomography pulmonary angiography (CTPA) is the gold standard test to investigate pulmonary embolism (PE). This technique carries significant radiation risk in young females because of radiosensitive breast and thyroid tissues. A high-pitched CT technique offers significant radiation dose reduction (RDR) and minimises breathing artefact. The addition of CT tube tin-filtration may offer further RDR. The aim of this retrospective study was to assess RDR and image quality (IQ) of high-pitch tin-filtered (HPTF)-CTPA against conventional-CTPA.MethodsRetrospective review of consecutive adult females age < 50 years undergoing high pitch tin filtration (HPTF) and standard pitch no tin filtration (SPNF) during a 3-year period beginning in November 2017. CTs in both groups were compared for radiation dose, pulmonary arteries contrast density (Hounsfield units (HU)) and movement artefact. Findings of both groups were compared with the Student’s T-test and Mann–Whitney U test, where p < 0.05 being considered significant. Diagnostic quality was also recorded.ResultsTen female patients (mean age 33, 6/10 pregnant) in HPTF group and 10 female patients (mean age 36, 1/10 pregnant) in SPNF group were included. The HPTF group achieved 93% RDR (dose length product: 25.15 mGy.cm vs 337.10 mGy.cm, p < 0.01). There was significant contrast density difference between the two groups in the main, left or right pulmonary arteries (322.72 HU, 311.85 HU and 319.41 HU in HPTF group vs 418.60 HU, 405.10 HU and 415.96 HU in SPNF group respectively, p = 0.03, p = 0.03 and p = 0.04). 8/10 HPTF group and 10/10 in the control group were > 250 HU in all three vessels; the remaining 2 HPTF CTPA were > 210HU. All CT scans in both groups were of diagnostic quality and none exhibited movement artefact.ConclusionThis study was the first to demonstrate significant RDR with the HPTF technique whilst maintaining IQ in patients undergoing chest CTPA. This technique is particularly beneficial in young females and pregnant females with suspected PE.
Journal Article
Monteggia fracture: an easy fracture to miss
2020
PurposeTo assess the incidence of missed Monteggia fracture by radiologists and bedside clinicians (emergency and orthopaedic doctors) at a tertiary hospital.MethodsA comprehensive search was conducted on Picture Archiving and Communication System (PACS) and electronic medical records (EMR) between Jan 2010 and April 2019. All consecutive paediatric and adult patients who presented to the emergency department with the diagnosis of Monteggia fracture were included. The patient’s emergency presentation medical notes and trauma film reports were compared. Most emergency presentations were discussed with orthopaedics; hence, this was combined as a single group (bedside clinician group). All images were blindly reviewed by a senior consultant radiologist. Results from the radiologist and bedside clinician groups were compared.ResultsFifty-one patients were identified; 4 were excluded as they were not true Monteggia fracture on review. Forty-seven patients were included in the study (age range 3–70 years, mean age 15 years). Thirty-three patients (70%) were correctly diagnosed by both groups. Twelve patients (25.5%) had a missed diagnosis by the radiologist’s group. Seven patients (14.9%) were missed by the bedside clinicians. Five patients (10.6%) were missed by both groups with fractures detected on re-presentations. The most commonly missed finding was a radial head dislocation/subluxation, followed by a subtle ulnar fracture (confirmed by periosteal reaction development on subsequent radiographs) and an ulnar plastic deformity.ConclusionThe Monteggia fracture is an important diagnosis, but it is not infrequently missed by radiologists and clinicians. Special attention to the radiocapitellar joint alignment and ulnar periosteum, and looking for a subtle ulnar fracture or plastic deformity would ensure correct diagnosis.
Journal Article
Th17 Cells in Immunity and Autoimmunity
2013
Th17 and IL-17 play important roles in the clearance of extracellular bacterial and fungal infections. However, strong evidence also implicates the Th17 lineage in several autoimmune disorders including multiple sclerosis, psoriasis, rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, and asthma. The Th17 subset has also been connected with type I diabetes, although whether it plays a role in the pathogenicity of or protection from the disease remains a controversial issue. In this review we have provided a comprehensive overview of Th17 pathogenicity and function, including novel evidence for a protective role of Th17 cells in conjunction with the microbiota gut flora in T1D onset and progression.
Journal Article