ScN/GaN(11Ì 00): A New Platform for the Epitaxy of Twin-Free Metal-Semiconductor Heterostructures.

We study the molecular beam epitaxy of rock-salt ScN on the wurtzite GaN(11̅00) surface. To this end, ScN is grown on freestanding GaN(11̅00) substrates and self-assembled GaN nanowires exhibiting (11̅00) sidewalls. On both substrates, ScN crystallizes twin-free thanks to a specific epitaxial relationship, namely ScN(110)[001]∥GaN(11̅00)[0001], providing a congruent, low-symmetry interface. The 13.1% uniaxial lattice mismatch occurring in this orientation mostly relaxes within the first few monolayers of growth by forming a near-coincidence site lattice, where 7 GaN planes coincide with 8 ScN planes, leaving the ScN surface nearly free of extended defects. Overgrowth of the ScN with GaN leads to a kinetic stabilization of the zinc blende phase, that rapidly develops wurtzite inclusions nucleating on {111} nanofacets, commonly observed during zinc blende GaN growth. Our ScN/GaN(11̅00) platform opens a new route for the epitaxy of twin-free metal-semiconductor heterostructures including closely lattice-matched GaN, ScN, HfN, and ZrN compounds.

Uniform large-area surface patterning achieved by metal dewetting for the top-down fabrication of GaN nanowire ensembles.

The dewetting of thin Pt films on different surfaces is investigated as a means to provide the patterning for the top-down fabrication of GaN nanowire ensembles. The transformation from a thin film to an ensemble of nanoislands upon annealing proceeds in good agreement with the void growth model. With increasing annealing duration, the size and shape uniformity of the nanoislands improves. This improvement speeds up for higher annealing temperature. After an optimum annealing duration, the size uniformity deteriorates due to the coalescence of neighboring islands. By changing the Pt film thickness, the nanoisland diameter and density can be quantitatively controlled in a way predicted by a simple thermodynamic model. We demonstrate the uniformity of the nanoisland ensembles for an area larger than 1 cm2. GaN nanowires are fabricated by a sequence of dry and wet etching steps, and these nanowires inherit the diameters and density of the Pt nanoisland ensemble used as a mask. Our study achieves advancements in size uniformity and range of obtainable diameters compared to previous works. This simple, economical, and scalable approach to the top-down fabrication of nanowires is useful for applications requiring large and uniform nanowire ensembles with controllable dimensions.

Dermatology teaching for undergraduate medical students in clinical routine - a structured four-week curriculum.

BACKGROUND: Dermatology teaching is fundamental for the promotion of young colleagues in our specialty. However, traditional teaching methods are being scrutinized by students of the 'Generation Y and Z', which can pose new challenges for teaching institutions. We therefore aimed to assess the motivational impact and reception of a newly created four-week curriculum containing modernized teaching methods integrated into clinical routine. METHODS: In this single-center study, 67 medical students completed this curriculum composed of weekly learning objectives including knowledge of morphological terms, 10 common dermatoses, communication and presentation skills. The participants provided information on their level of interest in dermatology each week as well as positive and negative aspects of the curriculum. RESULTS: During the curriculum a significant median increase in interest in dermatology was reported with no differences between the genders. Low initial interest could be improved, high initial interest maintained. Participants with an interest in scientific work (20.9%) were more motivated during the curriculum. The variety, quality of teaching and structure were the main aspects rated positively. Suggestions for improvement included the need for more teaching by senior doctors, transfer of responsibility, and a working environment updated to the latest technology standards. CONCLUSION: The presented curriculum was well received by the participants and allowed to better define learning preferences of new generations which can be helpful to modernize traditional teaching methods. Interest in scientific work could be a factor to identify students with a particularly strong interest in dermatology.

Growth mechanisms in molecular beam epitaxy for GaN-(In,Ga)N core-shell nanowires emitting in the green spectral range.

Using molecular beam epitaxy, we demonstrate the growth of (In,Ga)N shells emitting in the green spectral range around very thin (35 nm diameter) GaN core nanowires. These GaN nanowires are obtained by self-assembled growth on TiN. We present a qualitative shell growth model accounting for both the three-dimensional nature of the nanostructures as well as the directionality of the atomic fluxes. This model allows us, on the one hand, to optimise the conditions for high and homogeneous In incorporation and, on the other hand, to explain the influence of changes in the growth conditions on the sample morphology and In content. Specifically, the impact of the V/III and In/Ga flux ratios, the rotation speed and the rotation direction are investigated. Notably, with In acting as surfactant, the ternary (In,Ga)N shells are much more homogeneous in thickness along the nanowire length than their binary GaN counterparts.

Colchicine - Renaissance of an "ancient" drug.

Colchicine, which was already used by the ancient Egyptians, has recently experienced a renaissance in various medical disciplines, including dermatology. However, due to the potentially significant side effects of systemic use, many clinicians are cautious in their use of colchicine. This review provides a practical overview of the data on the established and emerging use of systemic and topical colchicine in dermatologic diseases.

Association between allergic sensitization and intestinal parasite infection in schoolchildren in Gqeberha, South Africa.

BACKGROUND: Inconsistent data exist regarding the influence of parasitic infection on the prevalence of allergic sensitization and disorders. OBJECTIVE: To investigate the impact of geohelminth and protozoan infections on sensitization patterns and allergic symptoms of children living in low-income communities in Gqeberha, South Africa. METHODS: In a cross-sectional study, 587 schoolchildren aged 8-12 years were recruited in June 2016 and screened for reactivity to common allergens by skin prick tests (SPTs) and for parasitic infections by stool examination. Additionally, questionnaires were completed to record allergic symptoms the children may have experienced. RESULTS: Positive SPTs were found in 237/587 children (40.4%), and about one-third of whom were polysensitized. Sensitizations were most frequently detected against the house dust mites (HDM) Dermatophagoides spp. (31.9%) and Blomia tropicalis (21.0%). Infections with geohelminths (Ascaris lumbricoides, Trichuris trichiura) were found in 26.8% and protozoan infections (Giardia intestinalis, Cryptosporidia spp.) in 13.9% of study participants. Mixed logistic regression analyses revealed negative associations between parasite infection and sensitization to Blomia tropicalis (OR: 0.54, 95% CI 0.33-0.89) and to Dermatophagoides spp. (OR 0.65, 95% CI 0.43-0.96), and between protozoan infection and allergic sensitization to any aeroallergen, although these associations were not significant when adjusted for false discovery. Geohelminth infection and intensity of geohelminth infection were both associated with reduced risk of polysensitization (OR 0.41, 95% CI 0.21-0.86), and this association remained significant with adjustment for false discovery. Reported respiratory symptoms were associated with HDM sensitization (ORs from 1.54 to 2.48), but not with parasite infection. CONCLUSIONS AND CLINICAL RELEVANCE: Our data suggest that geohelminth infection and high geohelminth infection intensity are associated with a reduced risk of polysensitization.

Corrigendum: Optical properties of GaN nanowires grown on chemical vapor deposited-graphene (2019 Nanotechnology 30 214005).

no abstract.

Internet and social media use in dermatology patients: Search behavior and impact on patient-physician relationship.

The traditional patient-physician relationship is being changed by the patients' searches for medical information on the Internet and in social media (SM). Freely available medical information online bears enormous potential but also holds dangers. In this cross-sectional, questionnaire-based study, the patients' motivation, preferences and unmet needs when searching for medical information online and the impact on the patient-physician relationship were assessed using Spearman's correlation coefficients, χ2 -tests and paired t-tests. Among 460 participants, 82.4% had already used the Internet/SM to gain medical information, but in only 9.4% their dermatologists had raised this topic. Online search for medical information was associated with female gender (P = .048), a higher skin-related burden (P = .020), higher level of education (P = .072), higher income (P = .019), anxiety (P = .004), and adnexal skin diseases (P = .043). For 16.1% of patients, "the Internet/SM" was their most important source of medical information; 81.4% deemed the impact of their online searches on their patient-physician relationship as neutral, 16.0% as positive, 2.6% as negative. The patients' top three unmet needs were "Online consultations", "Professional content on YouTube" and "Chat opportunities". Online search for medical information is a very important topic for most dermatology patients but it may not be adequately addressed by dermatologists. Our results indicate that from the patients`perspective such online searches do not have a significant impact on patient-physician relationship.

Global Trends in YouTube and Google Search Activity for Psoriasis and Atopic Eczema: Detecting Geographic Hot Spots, Blind Spots and Treatment Strategies.

To date, the geographical distribution and global trends of search activities on psoriasis and atopic eczema on Google and YouTube are widely unknown. The aim of this study was to identify geographic and temporal trends in YouTube and Google search activities for psoriasis and atopic eczema. We used specific filter settings on Google Trends to indicate the global search activity for ("Psoriasis") and ("Atopic Eczema") on Google and YouTube between January 1st , 2008 and August 7th , 2019. The four resulting data sets were analyzed and compared with respect to geographic distribution and temporal trends. Apart from a few "blind spots" (eg, Chad, Uzbekistan) the term "Psoriasis" was queried geographically fairly evenly distributed. The opposite was true for "Atopic Eczema", which was predominantly queried from a few "hot spots" (eg, United States, Commonwealth of Nations and Sweden). Since 2008, the search activity on YouTube for "Psoriasis" has tripled, while that for "Atopic Eczema" has decreased. On Google, by contrast, search activity has risen for both "Psoriasis" and "Atopic Eczema." Google Trends can be a useful tool to track people's/patients' interests and search search behavior over time, enabling, for instance, regionally tailored information and prevention campaigns.

Pitfall prayer marks: Recognition and appropriate treatment: A case report and review of literature.

Prayer marks are asymptomatic callosities resulting from repeated, extended pressure, and friction exerted on bony prominences when praying on hard ground. A 41-year-old woman with ulcerative colitis treated with infliximab was referred to our clinic due to skin changes on her feet that were suspected to be drug eruptions. The patient presented several asymptomatic, hyperpigmented, and hyperkeratotic plaques over the lateral malleoli suggesting that the lesions had a mechanical cause. Further exploration revealed that the patient, a practicing Muslim, prays in a sitting position called "Julus" several times a day. After color marking, the lesions over the lateral feet left a precise imprint on the underlay when the patient was asked to imitate the praying posture-thus proving the origin of the skin lesions. We searched the database on July 31, 2019 using the terms «prayer marks¼ OR «prayer nodules¼ OR "prayer callosities." Only electronically available publications were reviewed. Recognition of prayer marks is important to avoid misdiagnosis, performance of unnecessary diagnostic procedures, and to enhance the intercultural competence of clinicians who practice in multicultural societies.

Levocetirizine for the treatment of itch in psoriasis patients: An open-label pilot study in a real-world setting.

Itch is the most bothersome symptom in psoriasis, often leading to impaired quality of life. Treatment of psoriasis-induced itch is frequently unsatisfactory as the various therapies employed have a delayed onset of effect. Histamine-1 receptor (H1) antihistamines are not recommended in treatment guidelines as histamine is not considered a key mediator in psoriasis. However, patients using H1 antihistamines frequently report benefits in questionnaire-based studies. To address these contradictions, we examined the short-term effects of levocetirizine, a nonsedating H1 antihistamine, on psoriasis-related itch and itch-related quality of life. In this pilot study, patients with psoriasis-related itch received levocetirizine 5-10 mg daily as a concomitant treatment for 5 days. Change of itch intensity as measured by hourly itch ratings and the change of itch-related quality of life were measured at different time points. A total of 29 of 30 patients (96%) reported a decline in itch within 5 days. Mean itch reduction was 23% after Day 1 (p = .005), 40% after Day 3 (p < .001), and 41% after Day 5 (p < .001). Furthermore, itch-related quality of life also significantly improved after 5 days (p < .001). Only 2 of 30 patients (6.7%) reported mild sleepiness. Levocetirizine 5-10 mg daily as an add-on therapy seems to be an effective treatment to improve itch and itch-related quality of life within only a few days.

Fiction, Falsehoods, and Few Facts: Cross-Sectional Study on the Content-Related Quality of Atopic Eczema-Related Videos on YouTube.

BACKGROUND: In recent years, YouTube has become a recognized source of medical information for health care consumers. Although YouTube has advantages in this context, there are potential dangers as videos may contain nonscientific, misleading, or even harmful information. OBJECTIVE: As little is known about YouTube as a source of information on atopic dermatitis (AD), we investigated the content-related quality of AD videos and their perception among YouTube users. METHODS: The quality of the 100 most viewed AD videos was assessed by using the Global Quality Scale (GQS) and the DISCERN instrument. Videos were classified as "useful," "misleading," and "potentially harmful," and the correlations of viewers' ratings (likes) with the GQS and DISCERN scores were assessed. RESULTS: Among the 100 videos, 68.0% (68/100) and 62.0% (62/100) were of poor and very poor scientific quality, respectively. Additionally, 32.0% (32/100) of the videos were classified as useful, 48.0% (48/100) were classified as misleading, and 34.0% (34/100) were classified as potentially harmful. Viewers' ratings did not correlate with the GQS and DISCERN scores. Overall, 50.0% (50/100) of the videos were posted by private individuals and promoters of complementary/alternative treatments, 42.0% (42/100) by therapeutical advertisers, and only 8.0% (8/100) by nonprofit organizations/universities. CONCLUSIONS: Our study demonstrated that two-thirds of the videos analyzed were below acceptable medical quality standards and that many videos were disseminating misleading or even dangerous content. Subjective and anecdotal content was overrepresented, and viewers did not appear to be able to distinguish between high- and low-quality videos. Health promotion strategies by professional medical organizations are needed to improve their presence and visibility on YouTube.

Sexually transmitted coinfections in patients with anogenital warts - a retrospective analysis of 196 patients.

BACKGROUND AND OBJECTIVES: Anogenital warts (AGWs) are most commonly caused by low-risk human papillomavirus (HPV) types, and although they are the most frequent viral sexually transmitted infections (STIs), little is known about STI coinfections in affected patients. We therefore sought to assess STI coinfection rates in patients with AGW, specify STI coinfections and calculate the number needed to screen (NNS) for each STI. METHODS: A retrospective cross-sectional study analyzing data sets from AGW patients treated in our clinic between 2008-2016. RESULTS: 142/196 (72 %) patients had been variably screened for infections with HIV, HBV and HCV, Treponema pallidum, Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium and HSV. The STI coinfection rate in all tested patients was 24.6 %, yielding an NNS of 4.1 to detect any STI. Of note, the coinfection rate did not differ significantly between heterosexual men, homosexual men and women, respectively. The NNS for syphilis was 8.4, for HIV 14.0, for HCV 28.5 and for HBV 39.0. The NNS for asymptomatic patients tested for HSV, Chlamydia trachomatis and Mycoplasma genitalium were 1.4, 5.3 and 12.0, respectively. CONCLUSION: Due to the high prevalence of STI coinfections, AGW patients should be screened for other STIs.

Good vibrations: Itch induction by whole body vibration exercise without the need of a pruritogen.

Mechanically induced itch is an important cofactor in many patients with chronic itch. However, studying mechanical itch in a controlled environment is challenging because it is difficult to evoke. We investigated the use of whole body vibration (WBV) exercise, a training method used for musculoskeletal rehabilitation, to experimentally evoke mechanical itch. Mild to severe itch ascending from the soles to the groins was evoked in 16 of 20 healthy participants. We observed a characteristic on/off itch crescendo pattern reflecting the alternating intervals of vibration and no vibration. Wheals or an angioedema was absent, and serum mast cell tryptase was not increased by the exercise. Participants described the evoked sensation primarily as "itching" with some nociceptive components. Itch intensity correlated with the intensity of a concomitant erythema (R = 0.45, P = 0.043) and with the rise in skin temperature (R = 0.54, P = 0.017). Hence, WBV can be used as an easily applicable, noninvasive, investigator- and user-friendly framework for studying mechanical itch. Moreover, WBV allows to "switch itch on and off" rapidly and to simultaneously study interactions between itch, skin blood flow and skin temperature.

Implementation and evaluation of an algorithm for the management of scabies outbreaks.

BACKGROUND: Infestations with scabies mites are a global burden affecting individuals of all ages, classes and ethnicities. As poor sanitation and overcrowding favor the transmission of this highly contagious disease, epidemic outbreaks are frequently observed among displaced persons and asylum seekers. Due to the growing influx of refugees during the last years, public health authorities in host countries are frequently confronted with the challenge to treat individuals with diagnosed or suspected scabies promptly and effectively to avoid further spreading of the infestation. This study aimed to establish a straightforward and efficient algorithm for rapid screening and treatment of large numbers of patients with confirmed or suspected scabies infestations. METHODS: Forty-eight individuals (58% males, mean age 22.4 yrs.) from Syria with suspected scabies infestation were allocated to 3 colour-coded groups: (1) no signs or symptoms of infestation, (2) itch only, and (3) itch and typical skin lesions. Patients were treated with a single (group 1) or two doses of oral ivermectin at an interval of 7 days (group 2), or with a combination of 2 doses of ivermectin plus 2 applications of permethrin ointment at an interval of 7 days (group 3). Follow-ups were performed 4 weeks after initial treatments. RESULTS: All individuals with signs and/or symptoms of infestation had improved skin lesion; in 10/11 (90.9%) lesion had completely resolved. All individuals with initial itch only (n = 32) reported improvement of its intensity or complete resolution. None of the patients of group 1 developed itch or skin lesions. The algorithm was reapplied in 4 individuals (8.3%) after 4 weeks and the outbreak was completely controlled after 8 weeks. Colour-coding ensured fast flow of information between health-care providers at the interfaces of the algorithm. CONCLUSIONS: Our algorithm proved to be both highly efficient for treatment of large numbers of patients with suspected or diagnosed scabies infestation as well as for prevention of spreading of the disease. Hence, this algorithm is well suited for the management of scabies mass outbreaks.

The Absence of Evidence is Evidence of Non-Sense: Cross-Sectional Study on the Quality of Psoriasis-Related Videos on YouTube and Their Reception by Health Seekers.

BACKGROUND: Approximately 80% of internet users access health information online and patients with chronic illnesses especially rely on internet-based resources. YouTube ranks second among the most accessed websites worldwide and hosts an increasing number of videos with medical information. However, their quality is sometimes unscientific, misleading, or even harmful. OBJECTIVE: As little is known about YouTube as a source of information on psoriasis, we aimed to investigate the quality of psoriasis-related videos and, if necessary, point out strategies for their improvement. METHODS: The quality of the 100 most viewed psoriasis-related videos was assessed using the DISCERN instrument and the Global Quality Scale (GQS) by categorizing the videos into useful, misleading, and dangerous and by evaluating the reception of the videos by users. RESULTS: Evaluation of the videos exhibited a total of 117,221,391 views and a total duration of 10:28 hour. The majority of clips contained anecdotal personal experiences with complementary and alternative psoriasis treatments, topical treatments, and nutrition and diets being the most frequently addressed topics. While advertisements accounted for 26.0% (26/100) of the videos, evidence-based health information amounted to only 20.0% (20/100); 32.0% (32/100) of the videos were classified as useful, 52.0% (52/100) as misleading, and 11.0% (11/100) as even dangerous. The quality of the videos evaluated by DISCERN and GQS was generally low (1.87 and 1.95, respectively, on a 1 to 5 scale with 5 being the maximum). Moreover, we found that viewers rated poor-quality videos better than higher quality videos. CONCLUSIONS: Our in-depth study demonstrates that nearly two-thirds of the psoriasis-related videos we analyzed disseminate misleading or even dangerous content. Subjective anecdotal and unscientific content is disproportionately overrepresented and poor-quality videos are predominantly rated positively by users, while higher quality video clips receive less positive ratings. Strategies by professional dermatological organizations are urgently needed to improve the quality of information on psoriasis on YouTube and other social media.

Nanowires Bending over Backward from Strain Partitioning in Asymmetric Core-Shell Heterostructures.

The flexibility and quasi-one-dimensional nature of nanowires offer wide-ranging possibilities for novel heterostructure design and strain engineering. In this work, we realize arrays of extremely and controllably bent nanowires comprising lattice-mismatched and highly asymmetric core-shell heterostructures. Strain sharing across the nanowire heterostructures is sufficient to bend vertical nanowires over backward to contact either neighboring nanowires or the substrate itself, presenting new possibilities for designing nanowire networks and interconnects. Photoluminescence spectroscopy on bent-nanowire heterostructures reveals that spatially varying strain fields induce charge carrier drift toward the tensile-strained outside of the nanowires, and that the polarization response of absorbed and emitted light is controlled by the bending direction. This unconventional strain field is employed for light emission by placing an active region of quantum dots at the outer side of a bent nanowire to exploit the carrier drift and tensile strain. These results demonstrate how bending in nanoheterostructures opens up new degrees of freedom for strain and device engineering.

Crystal-Phase Quantum Wires: One-Dimensional Heterostructures with Atomically Flat Interfaces.

In semiconductor quantum-wire heterostructures, interface roughness leads to exciton localization and to a radiative decay rate much smaller than that expected for structures with flat interfaces. Here, we uncover the electronic and optical properties of the one-dimensional extended defects that form at the intersection between stacking faults and inversion domain boundaries in GaN nanowires. We show that they act as crystal-phase quantum wires, a novel one-dimensional quantum system with atomically flat interfaces. These quantum wires efficiently capture excitons whose radiative decay gives rise to an optical doublet at 3.36 eV at 4.2 K. The binding energy of excitons confined in crystal-phase quantum wires is measured to be more than twice larger than that of the bulk. As a result of their unprecedented interface quality, these crystal-phase quantum wires constitute a model system for the study of one-dimensional excitons.

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant.

Surface energies play a dominant role in the self-assembly of three-dimensional (3D) nanostructures. In this Letter, we show that using surfactants to modify surface energies can provide a means to externally control nanostructure self-assembly, enabling the synthesis of novel hierarchical nanostructures. We explore Bi as a surfactant in the growth of InAs on the {11̅0} sidewall facets of GaAs nanowires. The presence of surface Bi induces the formation of InAs 3D islands by a process resembling the Stranski-Krastanov mechanism, which does not occur in the absence of Bi on these surfaces. The InAs 3D islands nucleate at the corners of the {11̅0} facets above a critical shell thickness and then elongate along ⟨110⟩ directions in the plane of the nanowire sidewalls. Exploiting this growth mechanism, we realize a series of novel hierarchical nanostructures, ranging from InAs quantum dots on single {11̅0} nanowire facets to zigzag-shaped nanorings completely encircling nanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral line scans reveal that small surfactant-induced InAs 3D islands behave as optically active quantum dots. This work illustrates how surfactants can provide an unprecedented level of external control over nanostructure self-assembly.

Polarity-Induced Selective Area Epitaxy of GaN Nanowires.

We present a conceptually novel approach to achieve selective area epitaxy of GaN nanowires. The approach is based on the fact that these nanostructures do not form in plasma-assisted molecular beam epitaxy on structurally and chemically uniform cation-polar substrates. By in situ depositing and nitridating Si on a Ga-polar GaN film, we locally reverse the polarity to induce the selective area epitaxy of N-polar GaN nanowires. We show that the nanowire number density can be controlled over several orders of magnitude by varying the amount of predeposited Si. Using this growth approach, we demonstrate the synthesis of single-crystalline and uncoalesced nanowires with diameters as small as 20 nm. The achievement of nanowire number densities low enough to prevent the shadowing of the nanowire sidewalls from the impinging fluxes paves the way for the realization of homogeneous core-shell heterostructures without the need of using ex situ prepatterned substrates.