Coherence in Polycrystalline Thin Films of Twisted Molecular Crystals

Helicoidal crystallites in rhythmically banded spherulites manifest spectacular optical patterns in small molecules and polymers. It is shown that concentric optical bands indicating crystallographic orientations typically lose coherence (in-phase twisting) with growth from the center of nucleation. Here, coherence is shown to increase as the twist period decreases for seven molecular crystals grown from the melt. This dependence was correlated to crystallite fiber thickness and length, as well as crystallite branching frequency, a parameter that was extracted from scanning electron micrographs, and supported by numerical simulations. Hole mobilities for 2,5-didodecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP-C12) measured by using organic field-effect transistors demonstrated that more incoherent boundaries between optical bands in spherulites lead to higher charge transport for films with the same twist period. This was rationalized by combining our growth model with electrodynamic simulations. This work illustrates the emergence of complexity in crystallization processes (spherulite formation) that arises in the extra variable of helicoidal radial twisting. The details of the patterns analyzed here link the added complexity in crystal growth to the electronic and optical properties of the thin films.

Leveling up Organic Semiconductors with Crystal Twisting

The performance of crystalline organic semiconductors depends on the solid-state structure, especially the orientation of the conjugated components with respect to device platforms. Often, crystals can be engineered by modifying chromophore substituents through synthesis. Meanwhile, dissymetry is necessary for high-tech applications like chiral sensing, optical telecommunications, and data storage. The synthesis of dissymmetric molecules is a labor-intensive exercise that might be undermined because common processing methods offer little control over orientation. Crystal twisting has emerged as a generalizable method for processing organic semiconductors and offers unique advantages, such as patterning of physical and chemical properties and chirality that arises from mesoscale twisting. The precession of crystal orientations can enrich performance because achiral molecules in achiral space groups suddenly become candidates for the aforementioned technologies that require dissymetry.

Scaffold-Guided Crystallization of Oriented α-FAPbI3 Nanowire Arrays for Solar Cells

Perovskite nanowire arrays with large surface areas for efficient charge transfer and continuous highly crystalline domains for efficient charge transport exhibit ideal morphologies for solar-cell active layers. Here, we introduce a room temperature two-step method to grow dense, vertical nanowire arrays of formamidinium lead iodide (FAPbI3). PbI2 nanocrystals embedded in the cylindrical nanopores of anodized titanium dioxide scaffolds were converted to FAPbI3 by immersion in a FAI solution for a period of 0.5-30 min. During immersion, FAPbI3 crystals grew vertically from the scaffold surface as nanowires with diameters and densities determined by the underlying scaffold. The presence of butylammonium cations during nanowire growth stabilized the active α polymorph of FAPbI3, precluding the need for a thermal annealing step. Solar cells comprising α-FAPbI3 nanowire arrays exhibited maximum solar conversion efficiencies of >14%. Short-circuit current densities of 22-23 mA cm-2 were achieved, on par with those recorded for the best-performing FAPbI3 solar cells reported to date. Such large photocurrents are attributed to the single-crystalline, low-defect nature of the nanowires and increased interfacial area for photogenerated charge transfer compared with thin films.

Self-Patterning Tetrathiafulvalene Crystalline Films

Tetrathiafulvalene (TTF) crystals grown from the melt are organized as spherulites in which helicoidal fibrils growing radially from the nucleation center twist in concert with one another. Alternating bright and dark concentric bands are apparent when films are viewed between crossed polarizers, indicating an alternating pattern of crystallographic faces exposed at the film surface. Band-dependent reorganization of the TTF crystals was observed during exposure to methanol vapor. Crystalline growth appears on bright bands at the expense of the dark bands. After a 24 h period of exposure to methanol vapor, the original spherulites were completely restructured, and the films comprise isolated, concentric circles of crystallites whose orientations are determined by the initial TTF crystal fibril orientation. While the surface of these outgrowths appears faceted and smooth, cross-sectional SEM images revealed a semiporous inner structure, suggesting solvent-vapor-induced recrystallization. Collectively, these results show that crystal twisting can be used to rhythmically redistribute material. Crystal twisting is a common and often controllable phenomenon independent of molecular or crystal structure and therefore offers a generalizable path to spontaneous pattern formation in a wide range of materials.

Differentiation between Chondrosarcoma and Synovial Chondromatosis of the Temporomandibular Joint Using CT and MR Imaging

BACKGROUND AND PURPOSE

Chondrosarcoma and synovial chondromatosis of the temporomandibular joint share overlapping clinical and histopathologic features. We aimed to identify CT and MR imaging features to differentiate chondrosarcoma from synovial chondromatosis of the temporomandibular joint.

MATERIALS AND METHODS

The CT and MR images of 12 and 35 patients with histopathologically confirmed chondrosarcoma and synovial chondromatosis of the temporomandibular joint, respectively, were retrospectively reviewed. Imaging features including lesion size, center, enhancement, destruction/sclerosis of surrounding bone, infiltration into the tendon of the lateral pterygoid muscle, calcification, periosteal reaction, and osteophyte formation were assessed. A comparison between chondrosarcoma and synovial chondromatosis was performed with a Student t test for quantitative variables and the Fisher exact test or linear-by-linear association test for qualitative variables. Receiver operating characteristic analysis was performed to determine the diagnostic performance for differentiation of chondrosarcoma and synovial chondromatosis based on a composite score obtained by assigning 1 point for each of 9 imaging features.

RESULTS

High-risk imaging features for chondrosarcoma were the following: lesion centered on the mandibular condyle, destruction of the mandibular condyle, no destruction/sclerosis of the articular eminence/glenoid fossa, infiltration into the tendon of the lateral pterygoid muscle, absent or stippled calcification, periosteal reaction, internal enhancement, and size of ≥30.5 mm. The best cutoff value to discriminate chondrosarcoma from synovial chondromatosis was the presence of any 4 of these high-risk imaging features, with an area under the curve of 0.986 and an accuracy of 95.8%.

CONCLUSIONS

CT and MR imaging features can distinguish chondrosarcoma from synovial chondromatosis of the temporomandibular joint with improved diagnostic performance when a subcombination of 9 imaging features is used.

Variable Association of Physiologic Changes With Electrographic Seizure-Like Events in Infants Born Preterm

OBJECTIVES

To determine the incidence of seizure-like events in a cohort of infants born preterm as well as the prevalence of associated vital sign changes (heart rate [HR], respiratory rate, and pulse oximetry [SpO2]).

STUDY DESIGN

We performed prospective conventional video electroencephalogram monitoring on infants born at 23-30 weeks of gestational age during the first 4 postnatal days. For detected seizure-like events, simultaneously captured vital sign data were analyzed during the pre-event baseline and during the event. Significant vital sign changes were defined as HR or respiratory rate >±2 SD from the infant's own baseline physiologic mean, derived from a 10-minute interval before the seizure-like event. Significant change in SpO2 was defined as oxygen desaturation during the event with a mean SpO2 <88%.

RESULTS

Our sample included 48 infants with median gestational age of 28 weeks (IQR 26-29) and birth weight of 1125 g (IQR 963-1265). Twelve (25%) infants had seizure-like discharges with a total of 201 events; 83% (10/12) of infants had vital sign changes during these events, and 50% (6/12) had significant vital sign changes during the majority of the seizure-like events. Concurrent HR changes occurred the most frequently.

CONCLUSIONS

Individual infant variability was observed in the prevalence of concurrent vital sign changes with electroencephalographic seizure-like events. Physiologic changes associated with preterm electrographic seizure-like events should be investigated further as a potential biomarker to assess the clinical significance of such events in the preterm population.

Diagnosis and Management of Pediatric Chronic Hand Eczema: The PeDRA CACHES Survey

BACKGROUND

Chronic hand eczema (CHE) significantly impacts quality of life. Published literature on pediatric CHE (P-CHE) in North America including knowledge on epidemiology and standard evaluation and management is limited.

OBJECTIVE

Our objective was to assess diagnostic practices when evaluating patients with P-CHE in the US and Canada, produce data on therapeutic agent prescribing practices for the disorder, and lay the foundation for future studies.

METHODS

We surveyed pediatric dermatologists to collect data on clinician and patient population demographics, diagnostic methods, therapeutic agent selection, among other statistics. From June 2021 to January 2022, a survey was distributed to members of the Pediatric Dermatology Research Alliance (PeDRA).

RESULTS

Fifty PeDRA members responded stating that they would be interested in participating, and 21 surveys were completed. For patients with P-CHE, providers most often utilize the diagnoses of irritant contact dermatitis, allergic contact dermatitis, dyshidrotic hand eczema, and atopic dermatitis. Contact allergy patch testing and bacterial hand culture are the most used tests for workup. Nearly all utilize topical corticosteroids as first line therapy. Most responders report that they have treated fewer than six patients with systemic agents and prefer dupilumab as first-line systemic therapy.

CONCLUSIONS

This is the first characterization of P-CHE among pediatric dermatologists in the United States and Canada. This assessment may prove useful in designing further investigations including prospective studies of P-CHE epidemiology, morphology, nomenclature, and management.

Collimating the growth of twisted crystals of achiral compounds

A great proportion of molecular crystals can be made to grow as twisted fibrils. Typically, this requires high crystallization driving forces that lead to spherulitic textures. Here, it is shown how micron size channels fabricated from poly(dimethylsiloxane) (PDMS) serve to collimate the circular polycrystalline growth fronts of optically banded spherulites of twisted crystals of three compounds, coumarin, 2,5-bis(3-dodecyl-2-thienyl)-thiazolo[5,4-d]thiazole, and tetrathiafulvalene. The relationships between helicoidal pitch, growth front coherence, and channel width are measured. As channels spill into open spaces, collimated crystals "diffract" via small angle branching. On the other hand, crystals grown together from separate channels whose bands are out of phase ultimately become a single in-phase bundle of fibrils by a cooperative mechanism yet unknown. The isolation of a single twist sense in individual channels is described. We forecast that such chiral molecular crystalline channels may function as chiral optical wave guides.

Charge Transport in Twisted Organic Semiconductor Crystals of Modulated Pitch

Many molecular crystals (approximately one third) grow as twisted, helicoidal ribbons from the melt, and this preponderance is even higher in restricted classes of materials, for instance, charge-transfer complexes. Previously, twisted crystallites of such complexes present an increase in carrier mobilities. Here, the effect of twisting on charge mobility is better analyzed for a monocomponent organic semiconductor, 2,5-bis(3-dodecyl-2-thienyl)-thiazolo[5,4-d]thiazole (BDT), that forms twisted crystals with varied helicoidal pitches and makes possible a correlation of twist strength with carrier mobility. Films are analyzed by X-ray scattering and Mueller matrix polarimetry to characterize the microscale organization of the polycrystalline ensembles. Carrier mobilities of organic field-effect transistors are five times higher when the crystals are grown with the smallest pitches (most twisted), compared to those with the largest pitches, along the fiber elongation direction. A tenfold increase is observed along the perpendicular direction. Simulation of electrical potential based on scanning electron microscopy images and density functional theory suggests that the twisting-enhanced mobility is mainly controlled by the fiber organization in the film. A greater number of tightly packed twisted fibers separated by numerous smaller gaps permit better charge transport over the film surface compared to fewer big crystallites separated by larger gaps.

Serial surveys of Hong Kong medical students regarding attitudes towards HIV/AIDS from 2007 to 2017

INTRODUCTION

With widespread adoption of antiretroviral therapy, human immunodeficiency virus (HIV) epidemiology has changed since the late 2000s. Accordingly, attitudes towards the disease may also have changed. Because medical students are future physicians, their attitudes have important implications in access to care among patients with HIV/acquired immunodeficiency syndrome (AIDS). Here, we performed a survey to compare medical students' attitudes towards HIV/AIDS between the late 2000s (2007-2010) and middle 2010s (2014- 2017).

METHODS

From 2007 to 2010, we surveyed three cohorts of medical students at the end of clinical training to assess their attitudes towards HIV/AIDS. From 2014 to 2017, we surveyed three additional cohorts of medical students at the end of clinical training to compare changes in attitudes towards HIV/AIDS between the late 2000s and middle 2010s. Each set of three cohorts was grouped together to maximise sample size; comparisons were performed between the 2007-2010 and 2014-2017 cohorts.

RESULTS

From 2007 to 2010, 546 medical students were surveyed; from 2014 to 2017, 504 students were surveyed. Compared with students in the late 2000s, significantly fewer students in the mid-2010s initially encountered patients with HIV during attachment to an HIV clinic or preferred to avoid work in a field involving HIV/AIDS; significantly more students planned to specialise in HIV medicine. Student willingness to provide HIV care remained similar over time: approximately 78% of students were willing to provide care in each grouped cohort.

CONCLUSION

Although medical students had more positive attitudes towards HIV/AIDS, their willingness to provide HIV care did not change between the late 2000s and middle 2010s.

Resources Required for Implementation of SARS-CoV-2 Screening in Massachusetts K-12 Public Schools in Winter/Spring 2021

BACKGROUND

The financial costs and human resource requirements at the school and district level to implement a SARS-CoV-2 screening program are not well known.

METHODS

A consortium of Massachusetts public K-12 schools was formed to implement and evaluate a range of SARS-CoV-2 screening approaches. Participating districts were surveyed weekly about their programs, including: type of assay used, individual vs. pooled screening, approaches to return of results and deconvolution of positive pools, number and type of personnel, and hours spent implementing the screening program, and hours spent on program implementation.

RESULTS

In 21 participating districts, over 21 weeks from January to June 2021, the positivity rate was 0.0% to 0.21% among students and 0.0% to 0.13% among educators/staff. The average weekly cost to implement a screening program, including assay and personnel costs, was $17.00 per person tested; this was $46.68 for individual screenings and $15.61 for pooled screenings. The total weekly costs by district ranged from $1,644 to $93,486, and districts screened between 58 and 3675 people per week.

CONCLUSIONS

Where screening is recommended for the 2021 to 2022 school year due to high COVID-19 incidence, understanding the human resources and finances required to implement screening will assist district policymakers in planning.

Atypical keratosis pilaris-like lesions in a patient with Bethlem myopathy

Bethlem myopathy is a collagen VI-related myopathy. Collagen VI is primarily not only associated with the extracellular matrix of skeletal muscle, but is also found in the skin, blood vessels, and other organs. Dermatologic findings described for Bethlem myopathy include follicular hyperkeratosis and abnormal scar formation, although clinical and histopathologic photographs remain elusive in the literature. We present a case of atypical keratosis pilaris-like follicular lesions in a patient with Bethlem myopathy and provide histopathologic correlation to better characterize the development of skin lesions in this rare neuromuscular disease.

Not COVID Toes: Pool Palms and Feet in Pediatric Patients

So-called COVID toes is probably the most publicized cutaneous manifestation of COVID-19. The parents of 4 patients pursued dermatology evaluation with concerns about COVID-19 infection in their children who presented with symmetric, focal, erythematous lesions of the hands or feet, or both. We elicited a history of extended time in swimming pools for the 4 patients that was associated with COVID-19 restrictions during summer months of the pandemic and recognized findings of frictional and pressure-induced erythema and scaling, leading to a diagnosis of pool palms and feet-an extension of pool palms. It is important to recognize this diagnosis and provide reassurance to the patients and caregivers because the condition warrants no notable workup or therapeutic intervention.

Cardiorespiratory management of infants born at 22 weeks' gestation: The Iowa approach

The approach to clinical care of infants born at 22 weeks' gestation must be consistent and well-designed if optimal results are to be expected. Publications from several international centers have demonstrated that, although there may be variance in aspects of care in this vulnerable population, treatment should be neither random nor inconsistent. In designing a standardized approach, careful attention should be paid to the unique anatomy, physiology, and biochemistry of this vulnerable patient population. Emerging evidence, suggesting a link between cardiopulmonary health and longer-term sequela, highlights the importance of understanding the relationship between cardiorespiratory illnesses of the 22-week infant, treatments provided, and subsequent cardiopulmonary development. In this review we will provide an overview to our approach to cardiopulmonary assessment and treatment, with a particular emphasis on the importance of early recognition of atypical phenotypes, timely interventions with evidence-based treatments, and longitudinal monitoring.

How do patient-provider relationship continuity, gender, and language affect pediatric HPV vaccine acceptance?

Increasing human papillomavirus (HPV) vaccine uptake remains a challenge. We compared reasons for HPV vaccine acceptance between two Southern California pediatric clinics serving diverse populations: an academically affiliated resident clinic that offered little continuity of care (n = 53) and a private-practice clinic with well-established physician-patient relationships (n = 200). We found strong doctor recommendation and information dissemination about the importance of HPV vaccination were the most important drivers of acceptance across these distinct settings. The top-cited reasons for vaccine acceptance also varied by gender, language (English vs. Spanish), and clinic type. Findings point to the need for (1) robust provider education on vaccines, vaccine-preventable diseases, and vaccine hesitancy and (2) increased efforts to raise public awareness of the importance of HPV vaccination.

Nanoconfining solution-processed organic semiconductors for emerging optoelectronics

Solution-processable organic materials for emerging electronics can generally be divided into two classes of semiconductors, organic small molecules and polymers. The theoretical thermodynamic limits of device performance are largely determined by the molecular structure of these compounds, and advances in synthetic routes have led to significant progress in charge mobilities and light conversion and light emission efficiencies over the past several decades. Still, the uncontrolled formation of out-of-equilibrium film microstructures and unfavorable polymorphs during rapid solution processing remains a critical bottleneck facing the commercialization of these materials. This tutorial review provides an overview of the use of nanoconfining scaffolds to impose order onto solution-processed semiconducting films to overcome this limitation. For organic semiconducting small molecules and polymers, which typically exhibit strong crystal growth and charge transport anisotropy along different crystallographic directions, nanoconfining crystallization within nanopores and nanogrooves can preferentially orient the fast charge transport direction of crystals with the direction of current flow in devices. Nanoconfinement can also stabilize high-performance metastable polymorphs by shifting their relative Gibbs free energies via increasing the surface area-to-volume ratio. Promisingly, such nanoconfinement-induced improvements in film and crystal structures have been demonstrated to enhance the performance and stability of emerging optoelectronics that will enable large-scale manufacturing of flexible, lightweight displays and solar cells.

Adapting undergraduate paediatric medical education to the challenges of COVID-19 pandemic: perspective of NUS Medicine

COVID-19 significantly impacted the teaching-learning-assessment activities in many medical schools. In this article, we discuss the impact of COVID-19 on the Yong Loo Lin School of Medicine, National University of Singapore, focusing on paediatric training and the adaptations of the system and the people. The school developed strategies to promptly disseminate information and safety measures to protect all its staff and students. By leveraging on the school’s infrastructure for technology-enabled learning, good-quality medical training and reliable assessments were able to be carried out swiftly. The paediatric curriculum was crafted based on these principles, and it provided distance-based learning with live and interactive sessions to teach core clinical skills. The faculty also tapped on standardised patients to provide consistent and life-like scenarios. Measures were implemented to minimise challenges with technology-enabled learning. Collectively, efforts from the staff, support from the leadership and students’ adaptations tremendously helped to ease the transition.

Management of Severe Atopic Dermatitis in Pediatric Patients

Atopic dermatitis is a common, chronic inflammatory skin disorder, present in about 12% of children worldwide. Optimizing management of severe atopic dermatitis in pediatric patients is critical to reduce signs of inflammation, alleviate pruritus and sleep disturbance, minimize the development and/or impact of comorbidities, and improve the patient and caregiver's quality of life. Evaluating the longitudinal severity of pediatric atopic dermatitis is an important component of measuring therapeutic response and long-term management, and is different in clinical practice versus clinical trials. This article describes when and how to use different treatments for pediatric patients with severe atopic dermatitis, including topical medications, phototherapy, and systemic medical therapies (traditional immunosuppressants, biologics, and small molecule inhibitors). It also provides recommendations useful in clinical practice for nonpharmacologic interventions for pediatric patients with severe atopic dermatitis.

Orienting and shaping organic semiconductor single crystals through selective nanoconfinement

For organic semiconductor crystals exhibiting anisotropic charge transport along different crystallographic directions, nanoconfinement is a powerful strategy to control crystal orientation by aligning the fast crystallographic growth direction(s) with the unconfined axis(es) of nanoconfining scaffolds. Here, design rules are presented to relate crystal morphology, scaffold geometry, and orientation control in solution-processed small-molecule crystals. Specifically, organic semiconductor triisopropylsilylethynyl pyranthrene needle-like crystals with a dimensionality of n = 1 and perylene platelike crystals with n = 2 were grown from solution within nanoconfining scaffolds comprising cylindrical nanopores with a dimensionality of m = 1, representing one unconfined dimension along the cylinder axis, and those comprising nanopillar arrays with a dimensionality of m = 2. For m = n systems, native crystal growth habits were preserved while the crystal orientation in n = m direction(s) was dictated by the geometry of the scaffold. For n≠m systems, on the other hand, orientation control was restricted within a single plane, either parallel or perpendicular to the substrate surface. Intriguingly, control over crystal shape was also observed for perylene crystals grown in cylindrical nanopores (n > m). Within the nanopores, crystal growth was restricted along a single direction to form a needle-like morphology. Once growth proceeded above the scaffold surface, the crystals adopted their native growth habit to form asymmetric T-shaped single crystals with concave corners. These findings suggest that nanoporous scaffolds with spatially-varying dimensionalities can be used to grow single crystals of complex shapes.

Adherence of nurses to annual seasonal influenza vaccination over a 5-year period

BACKGROUND

Healthcare workers (HCWs) are at risk of influenza infection with associated nosocomial transmission. Sustained adherence to seasonal influenza vaccination uptake each year is important in epidemic control.

AIM

To assess the adherence of nurses to seasonal influenza vaccination over 5 years and its associated factors.

METHODS

A cross-sectional study was conducted among nurses after the winter influenza season in Hong Kong in March 2019. Based on influenza vaccine uptake rates in the 2014/15-2018/19 seasons, respondents were stratified into three groups: 'full adherence' (vaccine uptake in five seasons), 'partial adherence' (vaccine uptake in one to four seasons) and 'non-adherence' (no vaccine uptake). Stepwise multi-variable logistic regression was performed to determine the associations between adherence to annual influenza vaccination, respondents' characteristics and considerations for vaccination.

FINDINGS

Of 1306 nurses recruited, the majority were female (88%) with a median age of 36 years (interquartile range 30-46 years). The influenza vaccination uptake rate increased from 36% in the 2014/15 season to 47% in the 2018/19 season. After stratification, 39%, 40% and 21% of respondents were non-adherers, partial adherers and full adherers, respectively. Full adherence was significantly associated with female gender [adjusted odds ratio (aOR) 0.60], age ≥40 years (aOR 2.92), long-term care facility nurse (aOR 0.56), uptake during studentship (aOR 3.83), local prevalence of seasonal influenza (aOR 0.51) and expert opinion (aOR 4.04).

CONCLUSIONS

A limited proportion of nurses were fully adherent to seasonal influenza vaccination. Monitoring adherence, improving access to vaccines, and interventions targeting less-adherent HCWs are crucial.

Dynamics of the sub-ambient gelation and shearing of solutions of P3HT and P3HT blends towards active layer formation in bulk heterojunction organic solar cells

Organic solar cells (OSCs) containing an active layer consisting of a nanostructured blend of a conjugated polymer like poly(3-hexylthiophene) (P3HT) and an electron acceptor have the potential of competing against silicon-based photovoltaic panels. However, this potential is largely unfulfilled first due to interrelated production and stability issues of organic solar cells and second due to the unscalable nature of the generally employed spin coating process used for the fabrication of organic solar cells. Furthermore, alternatives to spin coating, especially relying on continuous polymer processing methods like extrusion and coating, cannot be readily applied due to the typically low shear viscosity and elasticity of polymer solutions making up the active layer. Recently, He et al. have reported that the gelation of P3HT with [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) under sub-ambient conditions can provide a new route to the processing of the active layers of bulk heterojunction solar cells. Furthermore, increases in power conversion efficiencies (PCEs) of the P3HT/PC60BM active layer were determined to be possible under certain shearing and thermal histories of the P3HT/PC60BM gels. Here oscillatory and steady torsional flows were used to investigate the gel formation dynamics of P3HT with a recently proposed non-fullerene acceptor o-IDTBR under sub-ambient conditions and compared with the gelation behavior of P3HT/PC60BM blends. The rheological material functions as well as the gel strengths defined on the basis of linear viscoelastic material functions, characterized via small-amplitude oscillatory shearing, were observed to be functions of the P3HT and o-IDTBR concentrations, the solvent used and the shearing conditions. Overall, the P3HT gels which formed upon quenching to sub-zero temperatures were found to be stable during small-amplitude oscillatory shear (linear viscoelastic range) but broke down even at the relatively low shear rates associated with steady torsional flows, suggesting that the shearing conditions used during the processing of gels of P3HT and blends of P3HT with small molecule acceptors can alter the gel structure, possibly leading to changes in the resulting active layer performance.

On the detection of surface spin freezing in iron oxide nanoparticles and its long-term evolution under ambient oxidation

Exchange bias (EB) effects linked to surface spin freezing (SSF) are commonly found in iron oxide nanoparticles, while signatures of SSF in low-field temperature-dependent magnetization curves have been much less frequently reported. Here, we present magnetic properties of dense assemblies of similar-sized (∼8 nm diameter) particles synthesized by a magnetite (sample S1) and a maghemite (sample S2) method, and the influence of long-term (4 year) sample aging under ambient conditions on these properties. The size of the EB field of the different sample (fresh or aged) states is found to correlate with (a) whether a low-temperature hump feature signaling the SSF transition is detected in out-of-phase ac susceptibility or zero-field-cooled (ZFC) dc magnetization recorded at low field and with (b) the prominence of irreversibility between FC and ZFC curves recorded at high field. Sample S1 displays a lower magnetization than S2, and it is in S1 where the largest SSF effects are found. These effects are significantly weakened by aging but remain larger than the SSF effects in S2, where the influence of aging is considerably smaller. A non-saturating component due to spin disorder in S1 also weakens with aging, accompanied by, we infer, an increase in the superspin and the radius of the ordered nanoparticle cores. X-ray diffraction and Mössbauer spectroscopy provide indication of maghemite-like stoichiometry in both aged samples as well as thicker disordered particle shells in aged-S1 relative to aged-S2 (crystallographically-disordered and spin-disordered according to diffraction and Mössbauer, respectively). The pronounced diminution in SSF effects with aging in S1 is attributed to a (long-term) transition, caused by ambient oxidation, from magnetite-like to maghemite-like stoichiometry, and a concomitant softening of the spin-disordered shell anisotropy. We assess the impact of this anisotropy on the nature of the blocking of the nanoparticle superspins.

Lithium and Chlorine-Rich Preparation of Mechanochemically Activated Antiperovskite Composites for Solid-State Batteries

Assembling all-solid-state batteries presents a unique challenge due to chemical and electrochemical complexities of interfaces between a solid electrolyte and electrodes. While the interface stability is dictated by thermodynamics, making use of passivation materials often delays interfacial degradation and extends the cycle life of all-solid cells. In this work, we investigated antiperovskite lithium oxychloride, Li₃OCl, as a promising passivation material that can engineer the properties of solid electrolyte-Li metal interfaces. Our experiment to obtain stoichiometric Li₃OCl focuses on how the starting ratios of lithium and chlorine and mechanochemical activation affect the phase stability. For substantial LiCl excess conditions, the antiperovskite phase was found to form by simple melt-quenching and subsequent high-energy ball-milling. Li₃OCl prepared with 100% excess LiCl exhibits ionic conductivity of 3.2 × 10⁻⁵ S cm⁻¹ at room temperature, as well as cathodic stability against Li metal upon the extended number of cycling. With a conductivity comparable to other passivation layers, and stable interface properties, our Li₃OCl/LiCl composite has the potential to stably passivate the solid-solid interfaces in all-solid-state batteries.

A review of reported cases of HIV pre-exposure prophylaxis failure with resultant breakthrough HIV infections

OBJECTIVES

Early randomized controlled trials (RCTs) have confirmed high efficacy of pre-exposure prophylaxis (PrEP) for preventing HIV infection in men who have sex with men (MSM) with high HIV exposure risk. Nevertheless, some PrEP failure cases have been reported despite adequate drug adherence. This review aims to summarize the common features of PrEP failure cases and discuss the implications of upscaling PrEP programmes.

METHODS

A search based on articles and clinical trials was conducted through Medline and OVID, with keywords for accessing publications reporting 'true' PrEP failure in the presence of documented adherence to daily regimen of co-formulated tenofovir disoproxil fumarate/emtricitabone.

RESULTS

Ten cases of 'true' PrEP failure were identified, all of which were preceded by continued practice of condomless anal sex, despite documented adherence. Dried blood spot and/or hair analyses provided supporting evidence of adherence in eight cases. There was strong association of PrEP failure with recurrent or multiple sexually transmitted diseases and infection with resistant HIV viruses. Seroconversion was usually atypical or delayed because of significantly suppressed viral load, making diagnosis a clinical challenge.

DISCUSSION

Although it is uncommon, 'true' PrEP failure can occur in a real-world situation, contrary to the outcome of early RCTs. Failure to identify HIV infection while on PrEP can potentially lead to the emergence of drug-resistant virus. To achieve effective HIV prevention, PrEP programmes should emphasize safer sexual practice in addition to drug adherence. Early identification of PrEP failure is crucial, which requires the development of highly sensitive assays and their clinical application.

Role of oxidative stress in clofazimine-induced cardiac dysfunction in a zebrafish model

BACKGROUND

Clofazimine (CFZ), a riminophenazine, is now commonly used in the treatment of multidrug-resistant tuberculosis. However, its use may be potentially associated with cardiac dysfunction in some individuals. In this study, the zebrafish heart, by merit of its developmental and genetic characteristics being in homology with that of human, was chosen as an animal model for evaluation of such dysfunction.

METHODS

Morphological and physiological parameters were used to assess cardiac dysfunction. Transcriptome analysis was performed, followed by validation with real-time quantitative PCR, for delineation of the relevant genomics.

RESULTS

Exposure of 2 dpf zebrafish to 4 mg/L CFZ for 2 days, adversely affected cardiac functions including significant decreases in HR, SV, CO, and FS, with observable pathophysiological developments of pericardial effusion and blood accumulation in the heart, in comparison with the control group. In addition, genes which respond to xenobiotic stimulus, related to oxygen transport, glutathione metabolism and extracellular matrix -receptor interactions, were significantly enriched among the differentially up-regulated genes. Antioxidant response element motif was enriched in the 5000 base pair upstream regions of the differentially expressed genes. Co-administration of N-acetylcysteine was shown to protect zebrafish against the development of CFZ-induced cardiac dysfunction.

CONCLUSIONS

This study suggests an important role of oxidative stress as a major pathogenetic mechanism of riminophenazine-induced cardiac dysfunction.

SARS-CoV-2 causing pneumonia-associated respiratory disorder (COVID-19): diagnostic and proposed therapeutic options

SARS-CoV-2 is responsible for the outbreak of severe respiratory illness (COVID-19) in Wuhan City, China and is now spreading rapidly throughout the world. The prompt outbreak of COVID-19 and its quick spread without any controllable measure defines the severity of the situation. In this crisis, a collective pool of knowledge about the advancement of clinical diagnostic and management for COVID-19 is a prerequisite. Here, we summarize all the available updates on the multidisciplinary approaches for the advancement of diagnosis and proposed therapeutic strategies for COVID-19. Moreover, the review discusses different aspects of the COVID-19, including its epidemiology; incubation period; the general clinical features of patients; the clinical features of intensive care unit (ICU) patients; SARS-CoV-2 infection in the presence of co-morbid diseases and the clinical features of pediatric patients infected with the SARS-CoV-2. Advances in various diagnostic approaches, such as the use of real-time polymerase chain reaction (RT-PCR), chest radiography, and computed tomography (CT) imaging; and other modern diagnostic methods, for this infection have been highlighted. However, due to the unavailability of adequate evidence, presently there are no officially approved drugs or vaccines available against SARS-CoV-2. Additionally, we have discussed various therapeutic strategies for COVID-19 under different categories, like the possible treatment plans with drug (antiviral drugs and anti-cytokines) therapy for disease prevention. Lastly, potentials candidates for the vaccines against SARS-CoV-2 infection have been described. Collectively, the review provides an overview of the SARS-CoV-2 infection outbreak along with the recent advancements and strategies for diagnosis and therapy of COVID-19.

Piloting a partially self-financed mode of human immunodeficiency virus pre-exposure prophylaxis delivery for men who have sex with men in Hong Kong

INTRODUCTION

Pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) 300 mg/emtricitabine (FTC) 200 mg is a proven strategy for preventing human immunodeficiency virus (HIV) transmission in men who have sex with men (MSM). This study aimed to test the feasibility and acceptability of PrEP delivered at a pilot clinic for MSM in Hong Kong, where PrEP service is currently unavailable.

METHODS

Partially self-financed PrEP was provided to HIV-negative adult MSM with high behavioural risk of HIV transmission after excluding hepatitis B infection and renal insufficiency. Participants received daily TDF/FTC for 30 weeks at 13.3% of the drug cost. Adherence and behaviours were monitored through questionnaires while creatinine and HIV/STI (sexually transmitted infection) incidence were monitored with point-of-care and laboratory tests. Preference for continuing with PrEP was evaluated at the end of the prescription period.

RESULTS

Seventy-one PrEP-naïve MSM were included in the study, of whom 57 (80%) were retained at the end of 28 weeks. Satisfactory adherence and self-limiting adverse events were reported, while none of the participants contracted HIV. Risk compensation was observed, with an STI incidence of 3.17 per 100 person-years. At the end of the prescription period, a majority (89%) indicated interest in continuing with PrEP. Preference for PrEP was associated with age ≥28 years and peer influence (P=0.04), while stigma was a concern. Price was a deterrent to self-financed PrEP, and only half (51%) considered a monthly cost of ≤HK$500 (US$1=HK$7.8) as reasonable.

CONCLUSIONS

A partially self-financed mode of PrEP delivery is feasible with good retention in MSM in Hong Kong.

Plasmonic Au nanorods stabilized within anodic aluminum oxide pore channels against high-temperature treatment

Au nanorods (Au NRs) are promising candidates for sensing applications due to their tunable localized surface plasmon resonance wavelength. At temperatures above 250 °C, however, these structures are morphologically unstable and tend to evaporate. We herein report a novel refractory plasmonic nanocomposite system comprising Au NRs entrapped in anodized aluminum oxide (AAO) scaffolds that are stable up to 800 °C. Au NRs were synthesized in the cylindrical pores of sapphire-supported AAO via in situ electroless deposition on catalytic Au nanoparticles (Au NPs) anchored on the pore walls. The morphological characteristics and surface-enhanced Raman scattering (SERS) functionality of Au NRs before and after heat treatment were evaluated using SEM, XRD and Raman spectroscopy. Compared to unconfined Au NRs that evolved into spherical particles at temperatures below 250 °C and subsequently evaporated from the substrate surface, the morphology of Au NRs in AAO was preserved upon heat treatment at temperatures up to 800 °C. Furthermore, by tuning the AAO scaffolds thickness and pore diameter, the aspect ratio (AR) of the entrapped Au NRs was varied from 2.4 to 7.8. The SERS sensitivity of Au NRs in AAO was found to increase with decreasing AR when the incident light was parallel to the rod longitudinal axis, in close agreement with the calculated fourth power of the local electromagnetic field using the finite-difference time domain method.

Multi-centre study on cultural dimensions and perceived attitudes of nurses towards influenza vaccination uptake

This study explored how cultural values affected Health Belief Model (HBM) components and the influenza vaccine uptake among nurses across three Asian populations using a survey conducted in 2017 (N = 3971). The vaccination coverages were 33.5% (Brunei), 35.6% (Hong Kong) and 69.5% (Singapore). Three HBM components (perceived susceptibility, perceived benefits and cues to action) were positively associated with vaccination. A direct negative link and an indirect positive link via HBM were observed between collectivism and vaccination, whereas a negative indirect link via HBM between power distance and vaccination was observed. Cultural values, notably collectivism, advanced HBM to study nurses' vaccination.

Transition of Dielectrophoresis-Assembled 2D Crystals to Interlocking Structures under a Magnetic Field

Aspherical cubic hematite colloids with cylindrical arms protruding from each face, referred to as "hexapods", were assembled via negative dielectrophoresis and then manipulated using an applied magnetic field. Upon application of an ac electric field, the hexapods aligned in close-packed linear chains parallel to the field direction. The chains then aggregated to the center of the device, with adjacent chains separated by distances approximately equal to twice the arm length. The resulting open packing structure exhibited cmm plane group symmetry due to the obstruction of arms, with a high density of incorporated defects. Subsequent application of a magnetic field to the dielectrophoresis (DEP)-assembled structure was found to anneal the colloidal crystal by reorienting the hexapods to align their intrinsic magnetic dipoles with the magnetic field direction. During reorganization, the colloidal packing density was found to decrease by more than 10% at both the center and edges of the crystal, accompanied by a significant loss of ordering, prior to redensification of the 2D lattice with fewer defects. Reorganization at the edge was 1.5 times faster than at the center, consistent with the need for cooperative colloidal motion to remove defects at the centers of the crystals.

Transcatheter arterial embolization for iatrogenic bleeding after endoscopic ultrasound-guided pancreaticobiliary drainage

PURPOSE

The purpose of this study was to report the incidence of massive bleeding after endoscopic ultrasound-guided transmural pancreaticobiliary drainage (EUS-TPBD) and the clinical outcomes in patients with this condition treated with transcatheter arterial embolization (TAE).

PATIENTS AND METHODS

We performed a 9-year retrospective analysis of 797 EUS-TPBD procedures (excluding gallbladder or pseudocysts) in 729 patients. Among them, twelve (12/729, 1.65%) patients were referred for TAE to manage active bleeding adjacent to the TPBD sites. There were 8 men and 4 women with a mean age of 66.1 years±13.4 (SD) (range: 45-89 years). The clinical and procedure data of these 12 patients were reviewed.

RESULTS

Thirteen TAE procedures in 12 patients were performed. The bleeding sites were the left hepatic artery (n=7), the right hepatic artery (n=3), the left gastric artery (n=1), the left accessory gastric artery (n=1) and gastroduodenal artery (n=1). TAE was performed with gelatin sponge particles (n=1), coil (n=1) and n-butyl-2 cyanoacrylate with/without coils (n=11), with technical and clinical success rates of 100% (13/13) and 85% (11/13), respectively. Re-bleeding following embolization with gelatin sponge particles occurred in one patient. Procedure-related ischemic hepatitis was observed in another patient with pancreatic cancer with portal vein involvement.

CONCLUSION

On the basis of our results, TAE using n-butyl-2 cyanoacrylate seems safe and effective for the treatment of bleeding after EUS-TPBD procedures. When the portal vein is compromised, TAE of the hepatic artery can cause ischemic liver damage.

Remarkable long-term stability of nanoconfined metal-halide perovskite crystals against degradation and polymorph transitions

Metal-halide perovskites are promising candidates to advance optoelectronic devices but are known to suffer from rapid material degradation. Here we demonstrate that nanoconfinement is an effective strategy for the long-term stabilization of metal-halide perovskite MAPbI3 crystals against humidity-induced degradation and temperature-induced polymorph transitions. Two-dimensional X-ray diffraction patterns of MAPbI3 films reveal an unprecedented air-stability of up to 594 days in non-chemically modified, non-passivated MAPbI3 films deposited on substrates imposing complete 2D confinement on the tens of nanometers length scale. Temperature-dependent X-ray diffraction analysis and optical spectroscopy further reveal the suppression of temperature-dependent phase transitions in nanoconfined MAPbI3 crystals. Most notably, the high-temperature cubic phase of MAPbI3, typically stable at temperatures above 327 K, remains present until a temperature of 170 K when the perovskite crystals are nanoconfined within the 100 nm diameter pores of anodized aluminum oxide templates. Photoluminescence mapping confirms that nanoconfined MAPbI3 crystals exhibit spatial uniformity on the tens of microns length scale, suggesting that nanoconfinement is an effective strategy for the formation of high-quality, stable MAPbI3 crystals across large areas.

The S Sign: A New Radiographic Tool to Aid in the Diagnosis of Slipped Capital Femoral Epiphysis

BACKGROUND

Children with slipped capital femoral epiphysis (SCFE) are often seen by an array of medical professionals prior to diagnosis. Patients with mild slips, slips with knee pain, or bilateral slips can occasionally present a diagnostic challenge that increases the risk of a delay in diagnosis and associated complications.

OBJECTIVES

This study introduces a new radiographic parameter, which we refer to as the S-sign, and analyzes its diagnostic utility on a frog-leg lateral radiograph.

METHODS

Twenty observers reviewed the radiographs from 35 patients with SCFE using Klein's line on anteroposterior pelvis radiographs and the S-sign on frog-leg lateral radiographs to diagnose an SCFE. Analysis included diagnostic outcomes and intraobserver and interobserver reliability.

RESULTS

The S-sign was more accurate at identifying an SCFE compared with Klein's line (92.4% vs. 79.2%, respectively). Sensitivity and specificity was greater for the S-sign compared with Klein's line (89.0% and 95.2% vs. 68.3% and 89.0%, respectively). A combination of the S-sign and Klein's line yielded a sensitivity of 96.5% and a specificity of 85.0%. The combination of tests was more diagnostic for an SCFE, compared with using the Klein's line, which was statistically significant (p < 0.001).

CONCLUSIONS

With increased awareness of the S-sign and a usage of the combined test, clinicians can more reliably and accurately diagnose an SCFE. Clinicians are more likely to diagnose an SCFE using the combined test, compared with solely relying on Klein's line, which we found to be statistically significant.

Frequency and risk factors of drug-induced liver injury during treatment of multidrug-resistant tuberculosis

OBJECTIVES

To investigate the risk factors for drug-induced liver injury (DILI) during the treatment of multidrug-resistant tuberculosis (MDR-TB) and to compare the frequency of DILI in patients with and those without chronic liver disease (CLD).

SETTING

This was a retrospective observational cohort study including 299 consecutive patients who started MDR-TB treatment from January 2009 to December 2013.

DESIGN

Of the 299 patients, 35 had alcoholic liver disease (ALD group), 16 had hepatitis B virus infection (HBV group) and 11 had hepatitis C virus infection (HCV group). The remaining 237 patients without CLD were selected as the control group.

RESULTS

DILI occurred in 29 (9.7%) patients. The frequency of DILI was significantly higher in the ALD (17.1%, P = 0.038), HBV (31.3%, P = 0.005) and HCV groups (27.3%, P = 0.037) than in the control group (6.3%). Among all patients taken together, having HBV and HCV infection were independent risk factors for the occurrence of DILI during MDR-TB treatment.

CONCLUSION

DILI during MDR-TB treatment occurred more frequently in patients with CLD due to ALD, HBV and HCV infection than in those without CLD.

Prevalence of hepatitis C infection and its associated factors in healthy adults without identifiable route of transmission

While hepatitis C virus (HCV) infection is long known to be associated with parenteral exposure, the specific route of transmission is not identified in a proportion of infected patients. Taking blood donors as the surrogate of healthy adults in the community in Hong Kong, we identified 91 HCV-infected donors (≤0.02% positive rate) in 2014-2016, of whom 46 were recruited in a mixed-method study to examine their transmission routes. A majority (75%) of the recruited donors were HCV RNA positive, with the predominant subtypes being 1b and 6a. From the results of the structured self-administered questionnaire and in-depth interviews, only 14 (30%) recruited donors could be traced to past history of contaminated blood transfusion (n = 9) or injection drug use (n = 5). Case-control analyses with 3 different control groups were performed to examine factors associated with HCV infection in multivariable analyses. High-risk sexual behaviour, body piercing, intramuscular injection and vaccine inoculation abroad, having lived abroad for >3 months were significantly associated with HCV in donors with otherwise nonidentifiable source of infection. While the specific route of transmission cannot be established for each person, associations with multiple parenteral exposures outside Hong Kong were observed. The World Health Organization has advocated for the global elimination of HCV by 2030. With a high proportion of HCV-infected persons who are unaware of their infections, HCV elimination could be hard to achieve.

Tenofovir disoproxil fumarate significantly decreases serum lipoprotein levels compared with entecavir nucleos(t)ide analogue therapy in chronic hepatitis B carriers

BACKGROUND

Tenofovir disoproxil fumarate (TDF) and entecavir (ETV) are first-line treatments for chronic hepatitis B (CHB). Studies suggest lipid lowering effect of TDF in human immunodeficiency virus positive (HIV+) individuals, but the effect on lipids and cardiovascular disease (CVD) risk in CHB is unknown.

AIM

To compare TDF vs ETV effects on lipid levels in CHB.

METHODS

In this retrospective cohort study, data on serum lipids and CVD risk factors at baseline and ~1 year on TDF or ETV were collected from CHB carriers. We used propensity score matched models to assess the effect on total cholesterol (TC), LDL-C, HDL and triglycerides (TGL).

RESULTS

In 348 patients, median age was 57 (IQR: 47-65 years), 63% were male, 77% were Asian, 19% were cirrhotic, 25% were HBeAg positive at baseline, and 72% received TDF vs 28% ETV. ETV-treated patients were older (median age: 60 vs 55, P<.01), had similar smoking and hypertension rates, but diabetes and dyslipidemia were more prevalent (19% vs 9%, P=.01; 14% vs 6%, P=.05, respectively). In propensity score matched models for age, gender, usage of lipid lowering agents, dyslipidemia and diabetes, TDF-treated patients were more likely to show a 20% decrease in TC (95% CI: 3%-25%), LDL-C (95% CI: 1%-25%) and HDL-C (CI: 10%-30%) levels compared with those on ETV. No change in TGL was observed in either group.

CONCLUSIONS

A greater decline in TC, LDL-C and HDL was observed in CHB carriers receiving TDF compared with ETV. These data may influence anti-viral choice in CHB carriers at risk for CVD.

Dielectrophoretic assembly of dimpled colloids into open packing structures

Reversible solid-state phase transitions between open- and close-packed structures in two-dimensional colloidal crystals comprising 1.8 μm dimpled spherical colloids were observed using negative dielectrophoresis. These asymmetrically-shaped colloids adopted lattices with cmm plane group symmetry and a packing fraction, ϕ, of 0.68 at low electric field strengths. At high electric field strengths, the close-packed p6m symmetry was observed, with ϕ = 0.90. The transition between open and close-packed structures was found to be reversible, depending on the applied electric field strength and frequency. Finite Fourier transform analysis and COMSOL simulations revealed the existence of repulsive interactions between colloids perpendicular to the electric field lines due to a concentration of the electric field at the edges of the dimpled regions of the colloids. The repulsive interactions resulted in a stretching of the hexagonal lattice perpendicular to the electric field lines, the magnitude of which depended on the electric field strength. By screening the colloids from the electric field in local potential wells, the entropically favored close-packed hexagonal lattice with ϕ = 0.91 was recovered.

Pattern of exposure to information and its impact on seasonal influenza vaccination uptake in nurses

BACKGROUND

Uptake of annual influenza vaccination of healthcare workers (HCWs) varies, and remains at a suboptimal level in many countries. As HCWs are often exposed to a variety of information about vaccination, the pattern of exposure may impact their decision; this deserves further investigation.

METHODS

Practising nurses in Hong Kong were invited to participate in an anonymous online survey in February 2016, after the winter seasonal peak. The questionnaire covered demographics, work nature and experiences, vaccination uptake history and reasons for vaccination decisions. Two behavioural categories for access to information were defined - passive exposure to information and active information-seeking - differentiated by the source, type and nature of information accessed. Chi-squared test, Mann-Whitney U-test and logistic regression were performed to compare vaccinated and unvaccinated nurses.

RESULTS

In total, 1177 valid returns were received from nurses. The median age of respondents was 32 years and 86% were female. The overall vaccination rate was 33%. Passive exposure to information from the workplace, professional body and social network was not predictive of vaccination decision, but passive exposure to information from mass media was predictive [odds ratio (OR) 1.78]. Active information-seeking, such as consulting a senior (OR 2.46), organizing promotional activities (OR 2.85) and undertaking an information search (OR 2.43), was significantly associated with increased vaccination uptake. A cumulative effect could be demonstrated for active information-seeking (OR 1.86), but not for passive exposure to information.

CONCLUSION

The current strategy of promotions and campaigns for seasonal influenza vaccination in HCWs may not be effective in increasing vaccination coverage. Measures targeting information-seeking behaviours may serve as an alternative approach.