Endovenous laser ablation therapy in children: applications and outcomes

BACKGROUND: Endovenous laser ablation is well recognized as the first-line treatment for superficial venous reflux with varicose veins in adults. It is not widely reported and is not an established practice in pediatric patients. OBJECTIVE: To illustrate a variety of pediatric venous conditions in which endovenous laser ablation can be utilized and to demonstrate its feasibility and safety in children. MATERIALS AND METHODS: We conducted a retrospective review of endovenous laser ablation procedures performed between January 2007 and July 2014 at two large pediatric institutions. RESULTS: We included 35 patients (17 males) who underwent endovenous laser ablation to 43 veins. Median age at first treatment was 14 years (range: 3-18 years). Median weight was 56 kg (range: 19-97 kg). Underlying diagnoses were common venous malformation (15), Klippel-Trenaunay syndrome (8), superficial venous reflux with varicose veins (5), verrucous hemangioma-related phlebectasia (4), venous varix (2) and arteriovenous fistula (1). The most common aim of treatment was to facilitate sclerotherapy. Thirty-four patients had treatment in the lower limbs and one patient in an upper limb. Ten of the veins treated with endovenous laser ablation had an additional procedure performed to close the vein. Complications attributable to endovenous laser ablation occurred in two patients (6%). One patient experienced post-procedural pain and one patient developed a temporary sensory nerve injury. Median clinical follow-up was 13 months (range: 28 days-5.7 years). The aim of the treatment was achieved in 29 of the 35 (83%) patients. CONCLUSION: Endovenous laser ablation is technically feasible and safe in children. It can be used in the management of a range of pediatric venous diseases with good outcomes

X-Ray Computed Tomography for Failure Mechanism Characterisation within Layered Pouch Cells: Part II

In Part I (1), the failure response of a 1 Ah layered pouch cell with a commercially available nickel manganese cobalt (NMC) cathode and graphite anode at 100% state of charge (SOC) (4.2 V) was investigated for two failure mechanisms: thermal and mechanical. The architectural changes to the whole-cell and deformations of the electrode layers are analysed after failure for both mechanisms. A methodology for post-mortem cell disassembly and sample preparation is proposed and demonstrated to effectively analyse the changes to the electrode surfaces, bulk microstructures and particle morphologies. Furthermore, insights into critical architectural weak points in LIB pouch cells, electrode behaviours and particle cracking are provided using invasive and non-invasive X-ray computed tomography techniques. The findings in this work demonstrate methods by which LIB failure can be investigated and assessed

Thermal Runaway of a Li-Ion Battery Studied by Combined ARC and Multi-Length Scale X-ray CT

Lithium ion battery failure occurs across multiple length scales. In this work, the properties of thermal failure and its effects on electrode materials were investigated in a commercial battery using a combination of accelerating rate calorimetry (ARC) and multi-length scale X-ray computed tomography (CT). ARC measured the heat dissipated from the cell during thermal runaway and enabled the identification of key thermal failure characteristics such as onset temperature and the rate of heat generation during the failure. Analysis before and after failure using scanning electron microscopy (SEM) and X-ray CT were performed to reveal the effects of failure on the architecture of the whole cell and microstructure of the cathode material. Mechanical deformations to the cell architecture were revealed due to gas generation at elevated temperatures (>200 °C). The extreme conditions during thermal runaway caused the cathode particles to reduce in size by a factor of two. Electrode surface analysis revealed surface deposits on both the anode and cathode materials. The link between electrode microstructure and heat generation within a cell during failure is analysed and compared to commercially available lithium ion cells of varying cathode chemistries. The optimisation of electrode designs for safer battery materials is discussed

Light activated antimicrobial agents can inactivate oral malodour causing bacteria.

Oral malodour is a common condition which affects a large proportion of the population, resulting in social, emotional and psychological stress. Certain oral bacteria form a coating called a biofilm on the tongue dorsum and degrade organic compounds releasing volatile sulfur compounds that are malodourous. Current chemical treatments for oral malodour such as mouthwashes containing chlorhexidine or essential oils, are not sufficiently effective at reducing the bacterial load on the tongue. One potential alternative to current chemical treatments for oral malodour is the use of light activated antimicrobial agents (LAAAs), which display no toxicity or antimicrobial activity in the dark, but when exposed to light of a specific wavelength produce reactive oxygen species which induce damage to target cells in a process known as photodynamic inactivation. This study aimed to determine whether oral malodour causing bacteria were susceptible to lethal photosensitization. Five bacterial species that are causative agents of oral malodour were highly sensitive to lethal photosensitization and were efficiently killed by methylene blue in conjunction with 665 nm laser light. Between 4.5-5 log10 reductions in the number of viable bacteria were achieved with 20 µM methylene blue and 14.53 J cm(-2) laser light for Porphyromonas gingivalis, Prevotella intermedia, Peptostreptococcus anaerobius and Solobacterium moorei. The number of viable cells fell below the limit of detection in the case of Fusobacterium nucleatum. These findings demonstrate that methylene blue in combination with 665 nm laser light is effective at killing bacteria associated with oral malodour, suggesting photodynamic therapy could be a viable treatment option for oral malodour

In situ x-ray computed tomography of zinc–air primary cells during discharge: correlating discharge rate to anode morphology

Zinc–air batteries have gained significant attention as safe battery alternatives, with high theoretical energy densities and a high abundance of their constituent materials. However, barriers to their widespread adoption include the need to improve their cycling lifetime, as well as stability and avoiding degradation mechanisms such as zinc dendrite growth and hydrogen-producing side reactions. X-ray computed tomography (CT) is a widely used technique for the study of batteries. In situ / operando x-ray CT has been increasingly used to study the zinc anode of zinc–air batteries to evaluate the interesting morphological changes occurring during the reaction from zinc (Zn) to zinc oxide (ZnO) during discharge (vice versa during charge). However, several studies have been carried out using synchrotron x-ray sources, which have limited availability for users. In this work, we present a comprehensive study of the discharge of commercial, primary zinc–air batteries using a laboratory-based x-ray source for in situ x-ray CT measurements. Four different discharge rates are investigated (C/30, C/60, C/90 and C/150), with tomograms collected at various stages throughout each discharge. Results confirm that with decreasing C-rate (i.e. decreasing discharge current) a greater volume of zinc is reacted, with average mass utilisations of 17%, 76%, 81% and 87% for C/30, C/60, C/90 and C/150, respectively. Furthermore, quantification using x-ray CT datasets showed that there is a direct correlation between the volume of zinc remaining in the cell and the state-of-charge of the cell, which deviated from linearity for the longer C-rates. Finally, a potential new mechanism for shape change is discussed, where a Zn particle is replaced with a pore of a similar volume. As well as improvements in statistical relevance gained from multiple repeats for each C-rate, the results presented here could be used in both modelling of battery performance, as well as consideration for future anode design concepts

Texture-Based Analysis of Fetal Organs in Fetal Growth Restriction

Fetal growth restriction (FGR) is common, affecting around 10% of all pregnancies. Growth restricted fetuses fail to achieve their genetically predetermined size and often weigh <10th centile for gestation. However, even appropriately grown fetuses can be affected, with the diagnosis of FGR missed before birth. Babies with FGR have a higher rate of stillbirth, neonatal morbidity such as breathing problems, and neurodevelopmental delay. FGR is usually due to placental insufficiency leading to poor placental perfusion and fetal hypoxia. MRI is increasingly used to image the fetus and placenta. Here we explore the use of novel multi-compartment Intravoxel Incoherent Motion Model (IVIM)-based models for MRI fetal and placental analysis, to improve understanding of FGR and quantify abnormalities and biomarkers in fetal organs. In 12 normally grown and 12 FGR gestational-age matched pregnancies (Median 28+ 4 wks±3+ 3 wks) we acquired T2 relaxometry and diffusion MRI datasets. Decreased perfusion, pseudo-diffusion coefficient, and fetal blood T2 values in the placenta and fetal liver were significant features distinguishing between FGR and normal controls (p-value <0.05). This may be related to the preferential shunting of fetal blood away from the fetal liver to the fetal brain that occurs in placental insufficiency. These features were used to predict FGR diagnosis and gestational age at delivery using simple machine learning models. Texture analysis was explored to compare Haralick features between control and FGR fetuses, with the placenta and liver yielding the most significant differences between the groups. This project provides insights into the effect of FGR on fetal organs emphasizing the significant impact on the fetal liver and placenta, and the potential of an automated approach to diagnosis by leveraging simple machine learning models

Interactions between HIV-1 Reverse Transcriptase and the Downstream Template Strand in Stable Complexes with Primer-Template

Background: Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) forms stable ternary complexes in which RT is bound tightly at fixed positions on the primer-template (P/T). We have probed downstream interactions between RT and the template strand in the complex containing the incoming dNTP (+1 dNTPNRTNP/T complex) and in the complex containing the pyrophosphate analog, foscarnet (foscarnetNRTNP/T complex). Methods and Results: UV-induced cross-linking between RT and the DNA template strand was most efficient when a bromodeoxyuridine residue was placed in the +2 position (the first template position downstream from the incoming dNTP). Furthermore, formation of the +1 dNTPNRTNP/T complex on a biotin-containing template inhibited binding of streptavidin when biotin was in the +2 position on the template but not when the biotin was in the +3 position. Streptavidin pre-bound to a biotin residue in the template caused RT to stall two to three nucleotides upstream from the biotin residue. The downstream border of the complex formed by the stalled RT was mapped by digestion with exonuclease RecJF. UV-induced cross-linking of the complex formed by the pyrophosphate analog, foscarnet, with RT and P/T occurred preferentially with bromodeoxyuridine in the +1 position on the template in keeping with the location of RT one base upstream in the foscarnetNRTNP/T complex (i.e., in the pre-translocation position). Conclusions: For +1 dNTPNRTNP/T and foscarnetNRTNP/T stable complexes, tight interactions were observed between RT an

Football-induced fatigue in hypoxia impairs repeated sprint ability and perceptual-cognitive skills

The present study investigated the effects of football-induced fatigue during hypoxia on RS and perceptual-cognitive skills. Ten male semi-professional football players underwent four sessions; a control session (0-m) to quantify RS in a non-fatigued state; and three further sessions at hypoxia (0-m;1500-m;3000-m) examining RS and perceptual-cognitive skill responses for a given physical workload. Anticipation and decision-making accuracy were obtained at the 30-min mark of each half. The mean number of trials (%) in which the player made the correct response was used for analysis. HR, TC, RPE and % saturation of O2 were measured during the warm-up, football-induced fatigue and RS test. It was found that HR, RPE and % saturation of O2 were different between conditions (P<0.05; ES=0.44-6.13). Further, RS were affected by football-induced fatigue for DC (4.8%; P=0.019; ES=0.68) and AV (5.5%; P=0.006; ES=0.79). In hypoxia, it was observed that football-induced fatigue decreased by 6.5% in DC, 6.3% in AV and 3.1% in PV at 1500-m compared to 0-m (P<0.05). Further significant changes were found at 3000-m compared to 0-m decreasing 12.8% in DC, 12.8% in AV and 6.2% in PV (P<0.0005). More pronounced declines in perceptual-cognitive skills were found as altitude increased (5.0-12.5 %; P<0.05; ES=1.17-2.41) and between both halves (5.3-6.7 %; P<0.05). The data demonstrates that the RS test was highly sensitive to fatigue and hypoxia for a given physical load. Simulated matches in hypoxia revealed larger decreases, when compared to normoxia in RS and perceptual-cognitive skills, highlighting the need for optimal acclimatisation strategies, including physical and technical preparation, prior to playing a

Prevention of lithium-ion battery thermal runaway using polymer-substrate current collectors

Isolating electronically conducting material from internal short circuits is a promising way to prevent the onset of thermal runaway within lithium-ion cells. Here, a metal-coated polymer current collector, which is designed to disconnect internal short circuits by withdrawing from the heating region, is tested in 18650 cells. In addition to having lower mass and manufacturing costs, cells with metal-coated polymer current collectors demonstrate a reduced risk of thermal runaway during nail penetration. High-speed synchrotron X-ray radiography of 18650 cells during nail-penetration testing, in tandem with pre- and post-mortem X-ray computed tomography, provides insights into the function of the current collectors. The results are compared with those of 18650 cells with standard commercial aluminum and copper current collectors. Cells with aluminum-coated polymer current collectors demonstrated 100% success in thermal runaway prevention during nail penetration, retaining a cell voltage >4.00 V, while standard cells consistently experienced thermal runaway