Mechanism of Laser-induced Field Emission

We have measured electron energy distribution curves (EDCs) of the laser-induced field emission from a tungsten tip. Field emission from photo-excited nonequilibrium electron distributions were clearly observed, while no enhanced field emission due to optical electric fields appeared up to values of 1.3 V/nm. Thus, we experimentally confirm the emission mechanism. Simulated transient EDCs show that electron dynamics plays a significant role in the laser-induced field emission. The results should be useful to find optimal parameters for defining the temporal and spectral characteristics of electron pulses for many applications based on pulsed field emission.Comment: 4 pages 4 figures 1 table, submitted to Physical Review Letter

Can AI Help Improve Water Quality? Towards the Prediction of Degradation of Micropollutants in Wastewater

Micropollutants have become a serious environmental problem by threatening ecosystems and the quality of drinking water. This account investigates if advanced AI can be used to find solutions for this problem. We review background, the challenges involved, and the current state-of-the-art of quantitative structure-biodegradation relationships (QSBR). We report on recent progress combining experiment, quantum chemistry (QC) and chemoinformatics, and provide a perspective on potential future uses of AI technology to help improve water quality

Can AI Help Improve Water Quality? Towards the Prediction of Degradation of Micropollutants in Wastewater

Micropollutants have become a serious environmental problem by threatening ecosystems and the quality of drinking water. This account investigates if advanced AI can be used to find solutions for this problem. We review background, the challenges involved, and the current state-of-the-art of quantitative structure-biodegradation relationships (QSBR). We report on recent progress combining experiment, quantum chemistry (QC) and chemoinformatics, and provide a perspective on potential future uses of AI technology to help improve water quality

Laser-induced Field Emission from Tungsten Tip: Optical Control of Emission Sites and Emission Process

Field-emission patterns from a clean tungsten tip apex induced by femtosecond laser pulses have been investigated. Strongly asymmetric field-emission intensity distributions are observed depending on three parameters: (1) the polarization of the light, (2) the azimuthal and (3) the polar orientation of the tip apex relative to the laser incidence direction. In effect, we have realized an ultrafast pulsed field-emission source with site selectivity of a few tens of nanometers. Simulations of local fields on the tip apex and of electron emission patterns based on photo-excited nonequilibrium electron distributions explain our observations quantitatively. Electron emission processes are found to depend on laser power and tip voltage. At relatively low laser power and high tip voltage, field-emission after two-photon photo-excitation is the dominant process. At relatively low laser power and low tip voltage, photoemission processes are dominant. As the laser power increases, photoemission from the tip shank becomes noticeable.Comment: 12 pages, 12 figures, submitted to Physical Review

Cocaine/Levamisole-Induced, Skin-Limited ANCA-Associated Vasculitis with Pyoderma Gangrenosum-like Presentation

The use of levamisole as the most frequent adulterant of cocaine has merged in previously unknown toxicities, notably a disease entity called cocaine/levamisole-associated autoimmune syndrome (CLAAS). Clinically, CLAAS can manifest with diverse cutaneous and extracutaneous features sharing common laboratory findings (neutropenia, autoantibody patterns). We report the case of a cocaine-abusing female patient with relapsing episodes of painful ulcers, worsening and expanding over a three-year period. The case exhibited all features of a drug-induced, skin-limited, ANCA-associated vasculitis, evolving over time to PG-like findings. In both disease stages, the patient responded well to the cessation of cocaine exposure and systemic glucocorticosteroids. This case demonstrates the continuous nature of cutaneous CLAAS manifestations in a single patient. CLAAS has become a major public health issue in the at-risk group of cocaine users, and clinicians should be alert of this condition when treating cocaine users presenting with single or multiple skin ulcerations

Activation of Nrf2 in fibroblasts promotes a skin aging phenotype via an Nrf2-miRNA-collagen axis

Aging is associated with progressive skin fragility and a tendency to tear, which can lead to severe clinical complications. The transcription factor NRF2 is a key regulator of the cellular antioxidant response, and pharmacological NRF2 activation is a promising strategy for the prevention of age-related diseases. Using a combination of molecular and cellular biology, histology, imaging and biomechanical studies we show, however, that constitutive genetic activation of Nrf2 in fibroblasts of mice suppresses collagen and elastin expression, resulting in reduced skin strength as seen in aged mice. Mechanistically, the "aging matrisome" results in part from direct Nrf2-mediated overexpression of a network of microRNAs that target mRNAs of major skin collagens and other matrix components. Bioinformatics and functional studies revealed high NRF2 activity in aged human fibroblasts in 3D skin equivalents and human skin biopsies, highlighting the translational relevance of the functional mouse data. Together, these results identify activated NRF2 as a promoter of age-related molecular and biomechanical skin features. Keywords: Aging; Collagen; Extracellular matrix; Nrf2; Skin mechanics; miRN

Activation of Nrf2 in fibroblasts promotes a skin aging phenotype via an Nrf2-miRNA-collagen axis

Aging is associated with progressive skin fragility and a tendency to tear, which can lead to severe clinical complications. The transcription factor NRF2 is a key regulator of the cellular antioxidant response, and pharmacological NRF2 activation is a promising strategy for the prevention of age-related diseases. Using a combination of molecular and cellular biology, histology, imaging and biomechanical studies we show, however, that constitutive genetic activation of Nrf2 in fibroblasts of mice suppresses collagen and elastin expression, resulting in reduced skin strength as seen in aged mice. Mechanistically, the “aging matrisome” results in part from direct Nrf2-mediated overexpression of a network of microRNAs that target mRNAs of major skin collagens and other matrix components. Bioinformatics and functional studies revealed high NRF2 activity in aged human fibroblasts in 3D skin equivalents and human skin biopsies, highlighting the translational relevance of the functional mouse data. Together, these results identify activated NRF2 as a promoter of age-related molecular and biomechanical skin features

Optical Control of Field-Emission Sites by Femtosecond Laser Pulses

We have investigated field emission patterns from a clean tungsten tip apex induced by femtosecond laser pulses. Strongly asymmetric modulations of the field emission intensity distributions are observed depending on the polarization of the light and the laser incidence direction relative to the azimuthal orientation of tip apex. In effect, we have realized an ultrafast pulsed field-emission source with site selectivity on the 10 nm scale. Simulations of local fields on the tip apex and of electron emission patterns based on photo-excited nonequilibrium electron distributions explain our observations quantitatively.Comment: 4 pages, submitted to Physical Review Letter

A plant-derived wound therapeutic for cost-effective treatment of post-surgical scalp wounds with exposed bone

BACKGROUND: To evaluate efficacy and cost-effectiveness of a plant-derived wound dressing (ONE), a mixture of hypericum oil (Hypericum perforatum L.) and neem oil (Azadirachta indica A. Juss.), in scalp wounds with exposed bone. PATIENTS AND METHODS: All patients with scalp wounds with exposed bone, following the excision of skin tumors, and treated with ONE in 2011 were included. Time of healing, wound size, area of exposed bone, ease of handling, pain, and complications were evaluated. Costs of dressings and nursing time were compared with those cited in literature for other treatment modalities. RESULTS: Fifteen consecutive patients with a mean age of 76.87 ± 10.3 years (59-90 years) were analyzed. The mean wound size was 10.9 ± 6.84 cm(2) (0.4-22.6 cm(2)) with 4.8 ± 5.9 cm(2) (0.3-20.7 cm(2)) of exposed bone. The time of complete healing by secondary intention was 8.1 (4-20) weeks. Rapid formation of granulation tissue was observed which after 4 weeks covered the entire exposed bone surface in 11 of 15 cases (73%). Dressing change was simple with no pain reported; no infections or other complications occurred. Using ONE for a mean healing time of 56.7 days resulted in mean costs of EUR 423.73, which is substantially lower than those published for fascia lata, negative pressure therapy, or collagen matrix followed by skin grafting (EUR 1,612.82, EUR 4,411.80 and EUR 1,503.72, respectively). CONCLUSION: This retrospective, non-controlled analysis supports ONE as a simple-to-use and safe treatment option for scalp wounds with exposed bone. Treatment costs compare favorably to those published for other treatment modalities

Buffered lidocaine 1%/epinephrine 1:100,000 with sodium bicarbonate (sodium hydrogen carbonate) in a 3:1 ratio is less painful than a 9:1 ratio: A double-blind, randomized, placebo-controlled, crossover trial

Background: Neutralizing (buffering) lidocaine 1%/epinephrine 1:100,000 solution (Lido/Epi) with sodium hydrogen carbonate (NaHCO3) (also called sodium bicarbonate) is widely used to reduce burning sensations during infiltration of Lido/Epi. Optimal mixing ratios have not been systematically investigated. Objectives: To determine whether a Lido/Epi:NaHCO3 mixing ratio of 3:1 (investigational medicinal product 1) causes less pain during infiltration than a mixing ratio of 9:1 (IMP2) or unbuffered Lido/Epi (IMP3). Methods: Double-blind, randomized, placebo-controlled, crossover trial (n = 2 × 24) with 4 investigational medicinal products (IMP1-4). Results: The 3:1 mixing ratio was significantly less painful than the 9:1 ratio (P = .044). Unbuffered Lido/Epi was more painful than the buffered Lido/Epi (P = .001 vs IMP1; P = .033 vs IMP2). IMP4 (NaCl 0.9% [placebo]) was more painful than any of the anesthetic solutions (P = .001 vs IMP1; P = .001 vs IMP2; P = .016 vs IMP3). In all cases, the anesthesia was effective for at least 3 hours. Limitations: Results of this trial cannot be generalized to other local anesthetics such as prilocaine, bupivacaine, or ropivacaine, which precipitate with NaHCO3 admixtures. Conclusions: Lido/Epi-NaHCO3 mixtures effectively reduce burning pain during infiltration. The 3:1 mixing ratio is significantly less painful than the 9:1 ratio. Reported findings are of high practical relevance, given the extensive use of local anesthesia today