Functionalization of Ti64 via Direct Laser Interference Patterning and Its Influence on Wettability and Oxygen Bubble Nucleation.

The nucleation of bubbles on solid surfaces is an important phenomenon in nature and technological processes like electrolysis. During proton-exchange membrane electrolysis, the nucleation and separation of the electrically nonconductive oxygen in the anodic cycle plays a crucial role to minimize the overpotential it causes in the system. This increases the efficiency of the process, making renewable energy sources and the "power-to-gas" strategy more viable. A promising approach is to optimize gas separation by surface functionalization in order to apply a more advantageous interface to industrial materials. In this work, the connection between the wettability and bubble nucleation of oxygen is investigated. For tailoring the wettability of Ti64 substrates, the direct laser interference patterning method is applied. A laser source with a wavelength of 1064 nm and a pulse duration of 12 ps is used to generate periodic pillar-like structures with different depths up to ∼5 µm. The resulting surface properties are characterized by water contact angle measurement, scanning electron microscopy, confocal microscopy, and X-ray photon spectroscopy. It was possible to generate structures with a water contact angle ranging from 20° up to nearly superhydrophobic conditions. The different wettabilities are validated based on X-ray photon spectroscopy and the different elemental composition of the samples. The results indicate that the surface character of the substrate adapts depending on the surrounding media and needs more time to reach a steady state for deeper structures. A custom setup is used to expose the functionalized surfaces to oxygen-oversaturated solutions. It is shown that a higher hydrophobicity of the structured surface yields a stronger interaction with the dissolved gas. This significantly enhances the oxygen nucleation up to nearly 350% by generating approximately 20 times more nucleation spots, but also smaller bubble sizes and a reduced detachment rate.

Hydrogen Bubble Size Distribution on Nanostructured Ni Surfaces: Electrochemically Active Surface Area Versus Wettability.

Emerging manufacturing technologies make it possible to design the morphology of electrocatalysts on the nanoscale in order to improve their efficiency in electrolysis processes. The current work investigates the effects of electrode-attached hydrogen bubbles on the performance of electrodes depending on their surface morphology and wettability. Ni-based electrocatalysts with hydrophilic and hydrophobic nanostructures are manufactured by electrodeposition, and their surface properties are characterized. Despite a considerably larger electrochemically active surface area, electrochemical analysis reveals that the samples with more pronounced hydrophobic properties perform worse at industrially relevant current densities. High-speed imaging shows significantly larger bubble detachment radii with higher hydrophobicity, meaning that the electrode surface area that is blocked by gas is larger than the area gained by nanostructuring. Furthermore, a slight tendency toward bubble size reduction of 7.5% with an increase in the current density is observed in 1 M KOH.

Tailored Laser Structuring of Tungsten Carbide Cutting Tools for Improving Their Tribological Performance in Turning Aluminum Alloy Al6061 T6.

In times of societal development, sustainability has become a major concern for many manufacturers in the metal industries. In this context, surface texturing of cutting tools offers a promising approach in terms of reducing energy consumption and material waste. In this work, direct laser interference patterning is utilized for producing periodic line-like structures with spatial periods of 2.0 µm and 5.5 µm on rake-flank faces of cemented tungsten carbide cutting inserts. Structure depths up to 1.75 µm are reached by controlling the applied number of laser pulses. Turning experiments under lubricated conditions carried out on Al 6061 T6 parts with textured and untreated tools are performed to determine their tribological performances. The used textured cutting tools can effectively decrease machining forces up to 17% due to the corresponding improvement in frictional behavior at the tool/chip interface. Furthermore, the laser-processed tools produce thinner chips and decrease the surface roughness by 31% of the aluminum work piece.

On the design and development of foamed GO-hydrogel nanocomposite surfaces by ultra-short laser processing.

Graphene oxide (GO) and reduced graphene oxide have outstanding qualities that could be exploited as reinforcement and antibacterial agents in a plethora of biomedical applications. In this contribution, it is reported the deployment of a polyacrylamide GO-hydrogel composite (GO@pAAm) which was photo-converted and structured by ultra-short laser irradiation using a direct laser writing (DLW) approach. The materials were characterized by Fourier Transform Infrared spectroscopy, scanning electron microscopy and confocal microscopy. The laser structure generates a multi-photo-induced effect: surface foaming and patterning, microdomains with enhanced selective water-swelling and effective GO photo-reduction. A first laser scan seems likely to induce the photo-reduction of GO and subsequent laser pulses trigger the structure/foaming. The photo-reduction of GO is evidenced by Raman spectroscopy by the relatively changing intensities of the D to G signals. Macroscopically by an increase in conductivity (decrease in sheet resistance fromRS-GO@pAAm= 304 ± 20 kΩ sq-1toRS-rGO@pAAm-DLW= 27 ± 8 kΩ sq-1) suggesting a reduction of the material measured by 4-Point-Probe.

Heating influence on hierarchical structures fabricated by direct laser interference patterning.

The combination of direct laser interference patterning (DLIP) with laser-induced periodic surface structures (LIPSS) enables the fabrication of functional surfaces reported for a wide spectrum of materials. The process throughput is usually increased by applying higher average laser powers. However, this causes heat accumulation impacting the roughness and shape of produced surface patterns. Consequently, the effect of substrate temperature on the topography of fabricated features requires detailed investigations. In this study, steel surfaces were structured with line-like patterns by ps-DLIP at 532 nm. To investigate the influence of substrate temperature on the resulting topography, a heating plate was used to adjust the temperature. Heating to 250 [Formula: see text]C led to a significant reduction of the produced structure depths, from 2.33 to 1.06 µm. The reduction is associated with the appearance of a different LIPSS type, depending on the grain orientation of the substrates and laser-induced superficial oxidation. This study revealed a strong effect of substrate temperature, which is also to be expected when heat accumulation effects arise from processing surfaces at high average laser power.

Hierarchical Microtextures Embossed on PET from Laser-Patterned Stamps.

Nowadays, the demand for surface functionalized plastics is constantly rising. To address this demand with an industry compatible solution, here a strategy is developed for producing hierarchical microstructures on polyethylene terephthalate (PET) by hot embossing using a stainless steel stamp. The master was structured using three laser-based processing steps. First, a nanosecond-Direct Laser Writing (DLW) system was used to pattern dimples with a depth of up to 8 µm. Next, the surface was smoothed by a remelting process with a high-speed laser scanning at low laser fluence. In the third step, Direct Laser Interference Patterning (DLIP) was utilized using four interfering sub-beams to texture a hole-like substructure with a spatial period of 3.1 µm and a depth up to 2 µm. The produced stamp was used to imprint PET foils under controlled temperature and pressure. Optical confocal microscopy and scanning electron microscopy imaging showed that the hierarchical textures could be accurately transferred to the polymer. Finally, the wettability of the single- and multi-scaled textured PET surfaces was characterized with a drop shape analyzer, revealing that the highest water contact angles were reached for the hierarchical patterns. Particularly, this angle was increased from 77° on the untreated PET up to 105° for a hierarchical structure processed with a DLW spot distance of 60 µm and with 10 pulses for the DLIP treatment.

Time-lapsed imaging of nanocomposite scaffolds reveals increased bone formation in dynamic compression bioreactors.

Progress in bone scaffold development relies on cost-intensive and hardly scalable animal studies. In contrast to in vivo, in vitro studies are often conducted in the absence of dynamic compression. Here, we present an in vitro dynamic compression bioreactor approach to monitor bone formation in scaffolds under cyclic loading. A biopolymer was processed into mechanically competent bone scaffolds that incorporate a high-volume content of ultrasonically treated hydroxyapatite or a mixture with barium titanate nanoparticles. After seeding with human bone marrow stromal cells, time-lapsed imaging of scaffolds in bioreactors revealed increased bone formation in hydroxyapatite scaffolds under cyclic loading. This stimulatory effect was even more pronounced in scaffolds containing a mixture of barium titanate and hydroxyapatite and corroborated by immunohistological staining. Therefore, by combining mechanical loading and time-lapsed imaging, this in vitro bioreactor strategy may potentially accelerate development of engineered bone scaffolds and reduce the use of animals for experimentation.

Evaluation of Two Fosphenytoin Loading Dose Regimens and Monitoring in Infants and Neonates Less Than Six Months of Age.

OBJECTIVES: The objectives of the study were to compare the free serum concentrations after different fosphenytoin loading dose strategies in patients younger than 6 months old and to investigate the frequency of seizure cessation following a loading dose of fosphenytoin. METHODS: This retrospective cohort study included neonates and infants admitted to a 150-bed children's hospital between August 1, 2014, and February 1, 2018. Patients were included if they were younger than 6 months old and had a postload free phenytoin serum concentration collected during the specified time frame. Patients were identified through a database query screening for the inclusion criteria. Patients were separated into 2 groups with the 15 mg/kg group as per protocol and the 20 mg/kg group as noted in common practice. Data collection included demographic information, fosphenytoin dose, time of administration of the fosphenytoin loading dose, time of sampling, free phenytoin serum concentration results, concomitant antiepileptic agents, albumin serum concentration, and total bilirubin serum concentration. RESULTS: Forty-one patients were included for analysis, 12 in the 15 mg/kg group and 29 in the 20 mg/kg group. The average free phenytoin concentration after the loading dose was 2.45 ± 0.54 mg/L in the 15 mg/kg group and 2.52 ± 0.66 mg/L in the 20 mg/kg group. Seizure cessation after the fosphenytoin loading dose was achieved in 3 of 12 (25%) patients in the 15 mg/kg group and in 13 of 29 (45%) patients in the 20 mg/kg group (p = 0.305). CONCLUSIONS: The study demonstrates that a traditional range of fosphenytoin loading dose (15-20 mg/kg) led to elevated postloading dose free phenytoin serum concentrations in the majority of patients with a seizure cessation rate of approximately 39%. The question remains as to what the optimal dose and target concentration should be in this patient population to achieve the best efficacy without risking associated toxicities.

A nano-carrier platform for the targeted delivery of nature-inspired antimicrobials using Engineered Water Nanostructures for food safety applications.

Despite the progress in the area of food safety, foodborne diseases still represent a massive challenge to the public health systems worldwide, mainly due to the substantial inefficiencies across the farm-to-fork continuum. Here, we report the development of a nano-carrier platform, for the targeted and precise delivery of antimicrobials for the inactivation of microorganisms on surfaces using Engineered Water Nanostructures (EWNS). An aqueous suspension of an active ingredient (AI) was used to synthesize iEWNS, with the 'i' denoting the AI used in their synthesis, using a combined electrospray and ionization process. The iEWNS possess unique, active-ingredient-dependent physicochemical properties: i) they are engineered to have a tunable size in the nanoscale; ii) they have excessive electric surface charge, and iii) they contain both the reactive oxygen species (ROS) formed due to the ionization of deionized (DI) water, and the AI used in their synthesis. Their charge can be used in combination with an electric field to target them onto a surface of interest. In this approach, a number of nature-inspired antimicrobials, such as H2O2, lysozyme, citric acid, and their combination, were used to synthesize a variety of iEWNS-based nano-sanitizers. It was demonstrated through foodborne-pathogen-inactivation experiments that due to the targeted and precise delivery, and synergistic effects of AI and ROS incorporated in the iEWNS structure, a pico- to nanogram-level dose of the AI delivered to the surface using this nano-carrier platform is capable of achieving 5-log reductions in minutes of exposure time. This aerosol-based, yet 'dry' intervention approach using iEWNS nano-carrier platform offers advantages over current 'wet' techniques that are prevalent commercially, which require grams of the AI to achieve similar inactivation, leading to increased chemical risks and chemical waste byproducts. Such a targeted nano-carrier approach has the potential to revolutionize the delivery of antimicrobials for sterilization in the food industry.

Continuous Intravenous Valproate as Abortive Therapy for Pediatric Status Migrainosus.

OBJECTIVE: This study describes the use of continuous intravenous valproate as an abortive therapy for pediatric status migrainosus. BACKGROUND: Intravenous valproate as a bolus dose has been shown to be an effective abortive therapy for status migrainosus in children; however, Valproate's pharmacokinetic profile suggests that it would be safer and more therapeutic as a continuous infusion. This dosing strategy results in less serum concentration fluctuations, more consistent therapeutic effects, and less adverse effects. METHODS: A retrospective chart review between August 2009 and August 2012 identified 83 patients who had presented with status migrainosus and had received continuous intravenous valproate after failing to respond to initial abortive treatment. These patients had received a 20 mg/kg loading dose, followed by continuous infusion at 1 mg/kg/h. Serum valproate levels had been drawn 4 hours and 24 hours after the loading dose. Infusion rate had been adjusted to maintain serum levels of 80 to 100 mcg/mL. Age-appropriate pain assessments had been recorded at regular intervals. Excellent response was defined as a 100% reduction in pain scores, moderate response as 50% to 99% reduction, and poor response as <50% reduction. RESULTS: Of the 83 patients, 55 (66.2%) had reported an excellent response, 4 (4.8%) a moderate response, and 24 (28.9%) a poor response. Of those reporting an excellent response, 76% had responded within 24 hours. Nausea (8.4%) and vomiting (2.4%) had been the only reported side effects. Twenty-four hour serum levels had been within the goal range 91.9% of the time. CONCLUSIONS: Continuous intravenous valproate is safe, easy to monitor, and therapeutic in the abortive treatment of status migrainosus in pediatric patients.

Surfer's myelopathy without surfing: a report of two pediatric patients.

INTRODUCTION: Surfer's myelopathy (SM) is a rare disorder described in subjects presenting with acute paraparesis while learning how to surf. It is thought to be secondary to spinal ischemia triggered by hyperextension. Spinal magnetic resonance imaging (MRI) shows changes consistent with spinal cord ischemia on T2-weighted and diffusion-weighted imaging (DWI). CASE PRESENTATION: We report two patients who presented with acute onset paraplegia shortly after spinal hyperextension. They had no physical or radiological evidence of soft tissue injury. Their clinical and imaging findings closely resemble those described in SM. DISCUSSION: We propose the use of the term 'acute hyperextension myelopathy' to categorize patients with spinal cord infarction secondary to hyperextension. DWI sequencing on MRI should be considered to evaluate for early signs of spinal cord ischemia in these patients. Use of a broader term for diagnostic classification can help include patients with spinal cord infarction due to a common mechanism.

Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates.

Pharmacokinetics and Clinical Utility of Valproic Acid Administered via Continuous Infusion.

INTRODUCTION: Valproic acid is a versatile antiepileptic drug that is often used in the acute care setting. Intravenous valproic acid lends itself well to a continuous infusion as it exhibits a relatively short half-life. We evaluated the pharmacokinetics and clinical efficacy of continuous infusion valproic acid in hospitalized patients with migraine and seizures. METHODS: A retrospective cohort study was performed utilizing information from the medical records of patients receiving an intravenous continuous infusion of valproic acid. Patients were included if they were aged 1 month to 85 years and they received a continuous infusion of valproic acid. Therapeutic response, common adverse effects, and the pharmacokinetic profile of valproic acid were evaluated. RESULTS: Continuous infusion valproic acid led to a concentration within the desired range (50-100 µg/ml) in 83.4% of patients, a rate that was higher in pediatric patients. The clinical response rate was also higher in pediatric patients with seizures or migraines and appeared to be better when the concentration was >75 µg/ml. Analysis of safety parameters suggests similar safety considerations to valproic acid when administered via intermittent infusion. CONCLUSIONS: Continuous infusion valproic acid appears to be a safe, effective, and predictable manner by which to administer valproic acid to pediatric and adult patients admitted to the hospital.

Detection of (133)Xe from the Fukushima nuclear power plant in the upper troposphere above Germany.

After the accident in the Japanese Fukushima Dai-ichi nuclear power plant in March 2011 large amounts of radioactivity were released and distributed in the atmosphere. Among them were also radioactive noble gas isotopes which can be used as tracers to test global atmospheric circulation models. This work presents unique measurements of the radionuclide (133)Xe from Fukushima in the upper troposphere above Germany. The measurements involve air sampling in a research jet aircraft followed by chromatographic xenon extraction and ultra-low background gas counting with miniaturized proportional counters. With this technique a detection limit of the order of 100 (133)Xe atoms in liter-scale air samples (corresponding to about 100 mBq/m(3)) is achievable. Our results provide proof that the (133)Xe-rich ground level air layer from Fukushima was lifted up to the tropopause and distributed hemispherically. Moreover, comparisons with ground level air measurements indicate that the arrival of the radioactive plume at high altitude over Germany occurred several days before the ground level plume.

Examining the stress response and recovery among children with migraine.

OBJECTIVE: This study compared physiological differences between children diagnosed with migraine and their healthy peers. METHOD: Physiological measures were obtained at baseline, after discussing an emotional stressor, and after a 5-min recovery period in 21 children with pediatric migraine and 32 healthy peers. Comparisons were also made on psychological measures investigating anxiety. RESULTS: Children with migraine exhibited a significantly higher pulse rate compared to comparison children at rest, and higher diastolic blood pressure and higher low-frequency/high-frequency ratio after a 5-min recovery from an emotional stressor. Additionally, when anxiety was entered as a covariate, group differences after the 5-min recovery period were no longer significant. CONCLUSIONS: Results suggest that relative to comparison children, children with migraine exhibit some physiological elevation at rest, as well as a prolonged physiological recovery period after an emotional stressor. Group differences after the 5-min recovery period suggest that children with migraine experience delayed sympathetic hyperarousal and prolonged sympathovagal imbalance. The treatment implications of these findings are discussed.

Lack of valproic acid-associated weight gain in prepubertal children.

We evaluated whether prepubertal children treated with valproic acid did not gain excessive weight. This retrospective study of children with epilepsy, aged <12 years at enrollment, examined weight gain associated with valproic acid or carbamazepine monotherapy. There was no significant difference between the valproic acid (n = 31) and carbamazepine (n = 49) treated groups in average duration of therapy or mean age. Body mass index scores at the beginning and end of the study were used to evaluate weight gain, while compensating for gains in height. For valproic acid, the linear mixed model detected no gain in body mass index z-scores over time (T = 0.25, DF = 17.3, P = 0.80), though it detected a significant gain in body mass index z-scores for carbamazepine (T = 2.32, DF = 36.7, P = 0.02). Results for McNemar chi-square tests were similar. No significant proportion change occurred among children on valproic acid (chi(2) = 2.0, P = 0.15), whereas a significant increase in the proportion of overweight children occurred on carbamazepine (chi(2) = 4.5, P = 0.03). We detected no excessive weight gain for children on valproic acid, whereas this was demonstrated for a similar socioeconomic group on carbamazepine.

Elastosis perforans serpiginosa, Down syndrome, and moyamoya disease.

A 16-year-old girl with Down syndrome, moyamoya disease, and history of a previous stroke presented with acute onset of left hemiparesis and elastosis perforans serpiginosa. Elastosis perforans serpiginosa in a patient with Down syndrome and moyamoya disease is a novel finding. Development of elastosis perforans serpiginosa in association with progressive vaso-occlusive disease may be a biological marker of progression of moyamoya disease.

Conversion to lamotrigine monotherapy from valproate monotherapy in older adolescent patients with epilepsy.

BACKGROUND: Pharmacokinetic interactions can make necessary anti-epileptic medication (AED) changes hazardous for children with epilepsy. We report the utility of a dosing algorithm designed to maintain stable trough lamotrigine (LTG) concentrations during conversion from valproate (VPA) to LTG monotherapy in adolescents aged 16-20 years. METHODS: Patients were enrolled into the study if they required a change in their AED regimen due to lack of efficacy or intolerable side effects. Conversion to LTG monotherapy took place in a four part treatment algorithm. Lamotrigine was escalated according to a target dose of 200 mg/day over 8-weeks. Valproate was withdrawn over a period of 2-6 weeks, depending on the initial dose. Lamotrigine dose was further escalated to 500 mg/day and continued for four weeks as mono therapy. Trough serum concentrations of LTG were measured during each phase of the trial. RESULTS: Twelve of 16 patients completed the study. After the LTG escalation to 200 mg/day, mean trough serum concentrations of 8.0 microg/mL did not differ significantly from the 9.5 microg/mL after VPA withdrawal or the 9.2 microg/mL after 4 weeks of monotherapy at 500 mg/day. Adverse events led to premature discontinuation for one subject. Two subjects withdrew due to worsening seizures during LTG monotherapy possibly due to non-compliance. Limitations of the trial include the open label design and small sample size of the sub-analysis. CONCLUSION: In adolescent patients, this algorithm produces stable LTG serum concentrations with favorable tolerability during a transition from VPA to LTG mono therapy.

Clinical utility of a continuous intravenous infusion of valproic acid in pediatric patients.

STUDY OBJECTIVE: To describe the dose-concentration relationship of a continuous intravenous infusion of valproic acid (VPA) in pediatric patients when a dosing protocol is used. DESIGN: Retrospective and concurrent chart review. SETTING: Tertiary care, 473-bed, academic medical center with a 120-bed, dedicated children's hospital. PATIENTS: Twenty-six pediatric patients (< 18 yrs old) who received VPA according to the protocol for continuous intravenous infusions between January 1, 2004, and March 31, 2006, identified by using a pharmacy order-entry system. MEASUREMENTS AND MAIN RESULTS: Patient demographics, VPA treatment regimens, clinical responses, and safety data were recorded and analyzed. Median patient age was 8.5 years (range 1.4-16 yrs). Approximately two thirds received VPA for seizures, and one third for migraines. Patients were given a mean +/- SD VPA loading dose of 28.5 +/- 5.2 mg/kg followed by a continuous infusion rate of 1 +/- 0.2 mg/kg/hour. Mean +/- SD serum concentration measured 4.5 +/- 1.6 hours after the loading dose was 83.3 +/- 22.8 microg/ml. Steady-state concentration at 23.3 +/- 3.0 hours after the start of the continuous infusion was 80.0 +/- 26.0 microg/ml. Postload and steady-state serum concentrations were within the target concentration of 50-100 microg/ml in 77% and 69% of patients, respectively. On further analysis, when the target range was expanded to 50-125 microg/ml (125 microg/ml was deemed acceptable if no adverse effects were noted), 89% and 92% of patients, respectively, had postload and steady-state VPA serum concentrations within this range. The response rate was excellent, with nearly 85% of patients achieving a complete or partial response to therapy. Adverse effects were generally mild and uncommon. CONCLUSIONS: The continuous-infusion protocol permitted rapid intravenous loading of VPA in pediatric patients while minimizing adverse events and achieving concentrations in the upper region of the therapeutic range.