Design and validation of a low-cost open-source impedance based quartz crystal microbalance for electrochemical research.

The quartz crystal microbalance (QCM) measurement technique is utilized in a broad variety of scientific fields and applications, where surface and interfacial processes are relevant. However, the costs of purchasing QCMs is typically high, which has limited its employment in education as well as by scientists in developing countries. In this article, we present an open-source QCM, built on the OpenQCM project, and using an impedance-based measurement technique (QCM-I), which can be built for <200 euro. Our QCM allows for simultaneous monitoring of the frequency change and dissipation, such that both soft and rigid materials can be characterized. In addition, our QCM measurements can be combined with simultaneous electrochemical measurement techniques (EQCM-I). We demonstrate the validity of our system by characterizing the electrodeposition of a rigid metallic film (Cu) and by the electropolymerization of aniline. Finally, we discuss potential improvements to our system.

Design, construction, and testing of an accurate low-cost humidistat for laboratory-scale applications.

Stable and precise control of humidity is imperative for a wide variety of experiments. However, commercially available humidistats (devices that maintain a constant humidity) are often prohibitively expensive. Here, we present a simple yet effective humidistat for laboratory-scale applications that can be easily and affordably (<€250) constructed based on an Arduino Uno as microcontroller, a set of proportional miniature solenoid valves, a gas washing bottle, and a humidity sensor. The microcontroller implements a PID controller that regulates the ratio of a dry and humid airflow. The design and implementation of the device, including a custom driver circuit for the solenoids, are described in detail, and the firmware is freely available online. Finally, we demonstrate its proper operation and performance through step response and long-term stability tests, which shows settling times of approx. 30 s and an attainable relative humidity range of 10-95.

Changes in Physical Activity in Relation to Body Composition, Fitness and Quality of Life after Primary Bariatric Surgery: a Two-Year Follow-Up Study.

PURPOSE: The success of bariatric surgery varies largely, which may relate to variance in adopting a physically active lifestyle. This study aimed to determine whether two-year changes in physical activity (PA) were associated with weight loss, fat-free mass, cardiorespiratory fitness and quality of life up to two years after bariatric surgery. MATERIALS AND METHODS: In this retrospective study, 3879 post-bariatric patients were divided into three groups: 1) decreased PA (n = 388), 2) maintained PA (n = 2002) or 3) increased PA (n = 1498). Measurements regarding PA (Baecke questionnaire), body composition (bioelectrical impedance analysis), estimated cardiorespiratory fitness (Åstrand test) and health-related quality of life (RAND-36) were performed preoperatively and two years post-surgery. RESULTS: Bariatric patients with increased PA had greater excess weight loss (76.3% vs. 73.2% vs. 72.9%, P < 0.001), greater increases in %fat-free mass (Δ14.0% vs. 13.0% vs. 12.8%; P < 0.001), larger improvements in VO2max (Δ11.8 vs. 10.2 vs. 8.0 ml/kg/min, P < 0.001), and larger increases in health related quality of life subscale scores (P < 0.05) compared to patients with maintained- and decreased PA. CONCLUSIONS: Bariatric patients who managed to induce improvements in habitual physical activity had better body composition, fitness and quality of life at 2 years post-surgery, compared to patients who maintained or even reduced their PA levels. These findings underscore the importance of perioperative-bariatric care programs to change lifestyle and achieve sustainable improvements in PA levels.

The Effects of Chronic Dialysis on Physical Status, Quality of Life, and Arterial Stiffness: A Longitudinal Study in Prevalent Dialysis Patients.

INTRODUCTION: It is widely known that dialysis patients have significantly impaired functional outcomes and arterial stiffness, but still few studies have investigated the effects of dialysis longitudinally by a multidimensional approach. We aimed to assess longitudinal patterns of physical activity (PA), physical functioning (PF), health-related quality of life (HrQoL), body composition (BC), and arterial stiffness in prevalent dialysis patients. MATERIALS AND METHODS: Thirty-nine prevalent dialysis patients (23 conventional hemodialysis [CHD] and 16 peritoneal dialysis) with a mean vintage of 25.7 (±22.1) months were included in this observational prospective study with a 2-year follow-up, and at baseline 20 healthy controls were included. Measurements were performed every 6 months. HrQoL was assessed using the Short Form-36 (SF-36) questionnaire. PA was assessed using the SenseWear™ Pro3 accelerometer. PF was assessed by walking speed, the PF subscale of the SF-36, and handgrip strength (HGS). BC was assessed using the Body Composition Monitor® and arterial stiffness by measuring carotid-femoral pulse wave velocity (PWV). The longitudinal trend was assessed using linear mixed models, correcting for sex, age, and dialysis vintage. For PWV, the trend was additionally corrected for diabetes and systolic blood pressure. RESULTS: After correction, no statistically significant changes over time were observed for the parameters of PA, PF, HrQoL, and BC. In the combined group and in the group of CHD patients only, a significant change was observed for PWV (overall trend: p = 0.007 and p = 0.008, respectively). A statistically significant difference at baseline was observed between dialysis patients and healthy controls in all parameters, except for HGS and PWV. DISCUSSION/CONCLUSION: We observed no statistically significant changes in functional outcomes during a 2-year follow-up period, but a significant increase was observed for arterial stiffness. These results might suggest that after a certain period in time, a relatively stable course is present in functional outcomes, but an ongoing deterioration in arterial stiffness occurs, which might increase the risk of cardiovascular disease and all-cause mortality in these patients.

Swelling of Poly(methyl acrylate) Brushes in Acetone Vapor.

Sensor platforms can benefit from the incorporation of polymer brushes since brushes can concentrate the analyte near the sensor surface. Brushes that absorb acetone vapor are of particular interest since acetone is an important marker for biological processes. We present a simple procedure to synthesize acetone-responsive poly(methyl acrylate) brushes. Using spectroscopic ellipsometry, we show that these brushes respond within seconds and swell by more than 30% when exposed to acetone vapor. Moreover, quartz crystal microbalance measurements demonstrate that the brushes can be exploited to increase the acetone detection sensitivity of sensors by more than a factor 6. Surprisingly, we find that the swelling ratio of the brushes in acetone vapor is independent of the grafting density and the degree of polymerization of the polymers in the brush. This is qualitatively different from swelling of the same brushes in liquid environments, where the swelling ratio decreases for increasing grafting densities. Yet, it indicates that the brushes are robust and reproducible candidates for implementation in vapor sensor systems.

Design and characterization of dielectric filled TM110 microwave cavities for ultrafast electron microscopy.

Microwave cavities oscillating in the TM110 mode can be used as dynamic electron-optical elements inside an electron microscope. By filling the cavity with a dielectric material, it becomes more compact and power efficient, facilitating the implementation in an electron microscope. However, the incorporation of the dielectric material makes the manufacturing process more difficult. Presented here are the steps taken to characterize the dielectric material and to reproducibly fabricate dielectric filled cavities. Also presented are two versions with improved capabilities. The first, called a dual-mode cavity, is designed to support two modes simultaneously. The second has been optimized for low power consumption. With this optimized cavity, a magnetic field strength of 2.84 ± 0.07 mT was generated at an input power of 14.2 ± 0.2 W. Due to the low input powers and small dimensions, these dielectric cavities are ideal as electron-optical elements for electron microscopy setups.

Time-of-flight electron energy loss spectroscopy by longitudinal phase space manipulation with microwave cavities.

The possibility to perform high-resolution time-resolved electron energy loss spectroscopy has the potential to impact a broad range of research fields. Resolving small energy losses with ultrashort electron pulses, however, is an enormous challenge due to the low average brightness of a pulsed beam. In this paper, we propose to use time-of-flight measurements combined with longitudinal phase space manipulation using resonant microwave cavities. This allows for both an accurate detection of energy losses with a high current throughput and efficient monochromation. First, a proof-of-principle experiment is presented, showing that with the incorporation of a compression cavity the flight time resolution can be improved significantly. Then, it is shown through simulations that by adding a cavity-based monochromation technique, a full-width-at-half-maximum energy resolution of 22 meV can be achieved with 3.1 ps pulses at a beam energy of 30 keV with currently available technology. By combining state-of-the-art energy resolutions with a pulsed electron beam, the technique proposed here opens up the way to detecting short-lived excitations within the regime of highly collective physics.

Increase in Physical Activity After Bariatric Surgery Demonstrates Improvement in Weight Loss and Cardiorespiratory Fitness.

BACKGROUND: Low cardiorespiratory fitness is strongly associated with cardiovascular diseases and mortality. Although increased physical activity can improve cardiorespiratory fitness, this relationship has not been examined in a large bariatric population undergoing perioperative care focusing on long-term lifestyle change. OBJECTIVES: To evaluate changes in physical activity, weight loss, and cardiorespiratory fitness up to 24 months after bariatric surgery, and to evaluate the relationships of change in physical activity with weight loss and change in cardiorespiratory fitness. MATERIALS AND METHODS: Four thousand seven hundred eighty-five patients who underwent primary Roux-en-Y gastric bypass or sleeve gastrectomy between January 2012 and December 2014 were included. Physical activity was assessed by the Baecke questionnaire (work, leisure, and sport activity) and cardiorespiratory fitness, defined as VO2max relative to fat-free mass (VO2max/FFM), was assessed by the Åstrand test. RESULTS: Twenty-four months postoperative, significant improvements were seen in sport and leisure activity assessments (n = 3548, P < 0.001), weight loss (n = 3695, P < 0.001), and VO2max/FFM (n = 1852, P < 0.001). Furthermore, regression analysis showed that change in leisure activity was positively associated with weight loss (n = 3535, ß = 1.352, P < 0.001) and change in sport activity was positively associated with change in VO2max/FFM (n = 1743, ß = 1.730, P < 0.001). CONCLUSION: Bariatric surgery complemented by a comprehensive bariatric care program can lead to improvement in physical activity, as well as weight loss and improvement in cardiorespiratory fitness. The positive associations of change in leisure activity with weight loss and change in sport activity with cardiorespiratory fitness suggest that bariatric care programs can enhance postoperative outcomes by improving the patient's physical activity.

High quality ultrafast transmission electron microscopy using resonant microwave cavities.

Ultrashort, low-emittance electron pulses can be created at a high repetition rate by using a TM110 deflection cavity to sweep a continuous beam across an aperture. These pulses can be used for time-resolved electron microscopy with atomic spatial and temporal resolution at relatively large average currents. In order to demonstrate this, a cavity has been inserted in a transmission electron microscope, and picosecond pulses have been created. No significant increase of either emittance or energy spread has been measured for these pulses. At a peak current of 814 ±â€¯2 pA, the root-mean-square transverse normalized emittance of the electron pulses is ɛn,x=(2.7±0.1)·10-12 m rad in the direction parallel to the streak of the cavity, and ɛn,y=(2.5±0.1)·10-12 m rad in the perpendicular direction for pulses with a pulse length of 1.1-1.3 ps. Under the same conditions, the emittance of the continuous beam is ɛn,x=ɛn,y=(2.5±0.1)·10-12 m rad. Furthermore, for both the pulsed and the continuous beam a full width at half maximum energy spread of 0.95 ±â€¯0.05 eV has been measured.

Theory and particle tracking simulations of a resonant radiofrequency deflection cavity in TM110 mode for ultrafast electron microscopy.

We present a theoretical description of resonant radiofrequency (RF) deflecting cavities in TM110 mode as dynamic optical elements for ultrafast electron microscopy. We first derive the optical transfer matrix of an ideal pillbox cavity and use a Courant-Snyder formalism to calculate the 6D phase space propagation of a Gaussian electron distribution through the cavity. We derive closed, analytic expressions for the increase in transverse emittance and energy spread of the electron distribution. We demonstrate that for the special case of a beam focused in the center of the cavity, the low emittance and low energy spread of a high quality beam can be maintained, which allows high-repetition rate, ultrafast electron microscopy with 100 fs temporal resolution combined with the atomic resolution of a high-end TEM. This is confirmed by charged particle tracking simulations using a realistic cavity geometry, including fringe fields at the cavity entrance and exit apertures.

Time-of-flight electron energy loss spectroscopy using TM110 deflection cavities.

We demonstrate the use of two TM110 resonant cavities to generate ultrashort electron pulses and subsequently measure electron energy losses in a time-of-flight type of setup. The method utilizes two synchronized microwave cavities separated by a drift space of 1.45 m. The setup has an energy resolution of 12 ± 2 eV FWHM at 30 keV, with an upper limit for the temporal resolution of 2.7 ± 0.4 ps. Both the time and energy resolution are currently limited by the brightness of the tungsten filament electron gun used. Through simulations, it is shown that an energy resolution of 0.95 eV and a temporal resolution of 110 fs can be achieved using an electron gun with a higher brightness. With this, a new method is provided for time-resolved electron spectroscopy without the need for elaborate laser setups or expensive magnetic spectrometers.

[A boy with a skin lesion after a henna tattoo]. / Een jongen met een huidafwijking na hennatatoeage.

An 11-year-old boy got a temporary black henna tattoo while on vacation. After 3 days he developed an itching rash at the site of the tattoo, that spread to the rest of the body. This was most likely an allergic contact dermatitis and erythema exsudativum multiforme minor caused by the often high concentrations of the strong sensitizer para-phenylenediamine (PPD) in the henna.

Severe pyoderma gangrenosum unresponsive to etanercept and adalimumab.

BACKGROUND: A 74-year-old female with severe and therapy-resistant pyoderma gangrenosum (PG) was treated for more than 40 years with topical antibacterial ointments, topical and systemic corticosteroids, dapsone and azathioprine. Generally, immunosuppression is the mainstay of treatment of PG, but in our patient cyclosporine had to be discontinued because of significant serious side effects. An attempt was made to decrease the amount of steroids, but tapering of the prednisone dose resulted in relapses of PG. OBSERVATION: Off-label use of etanercept resulted in a temporary limited clinical improvement. After 6 months, initial clinical improvement reduced and adalimumab was started. Unfortunately, after 6 months of adalimumab no clinical improvement was seen. Therefore, systemic corticosteroids had to be continued with very good clinical results. CONCLUSION: In concordance with previous results of several other studies, reviews and case reports, we presume that possibly both etanercept and adalimumab could be excellent therapeutic alternatives in the treatment of PG. Unfortunately, the effectiveness of both etanercept and adalimumab were very limited in our case. Literature research revealed no other successful studies on the off-label use of other immunomodulators as an alternative treatment option for PG. However, infliximab or ustekinumab could be alternative treatment options.

A comparative study of pulsed 532-nm potassium titanyl phosphate laser and electrocoagulation in the treatment of spider nevi.

OBJECTIVE: To assess the clinical efficacy and safety of potassium titanyl phosphate (KTP) laser treatment and electrocoagulation (EC) for the treatment of spider nevi (SN). METHOD: A randomized single-blind intrapatient comparison study was performed. A blinded observer and patients reported the clinical treatment outcome and pain on a visual analogue scale (0-10). Side effects were noted if present. RESULTS: Mean physician-rated clinical efficacy scores+/-standard error of the mean were 7.7+/-0.7 for KTP laser and 6.2+/-0.9 for EC treatment (p=.05). Patient-rated mean clinical efficacy of KTP laser was 8.3+/-0.6 and of EC was 7.3+/-0.7 (p=.09). Stratification for potential confounding bias, such as location of SN, central bulging vein, and diameter (p=.25) of the treated SN did not reveal any statistically significant differences between the treatments. Treatment with KTP or EC did not result in scarring or pigmentary changes. Pain was reported for KTP treatment (3.1+/-0.4) and EC (6.4+/-0.7) (p<.05). CONCLUSION: Clinical efficacy of KTP laser and EC for SN is comparable, although there is a tendency toward an advantage in favor of the KTP laser. KTP laser treatment was less painful.

Concurrent anion...pi interactions between a perchlorate ion and two pi-acidic aromatic rings, namely pentafluorophenol and 1,3,5-triazine.

The rational design of a ligand containing two electron-poor pi-rings, i.e. a triazine and a pentafluorophenoxy groups, has allowed the preparation of a copper complex where both the anticipated anion...pi interactions are present.

Histamine, a vasoactive agent with vascular disrupting potential, improves tumour response by enhancing local drug delivery.

Tumour necrosis factor (TNF)-based isolated limb perfusion (ILP) is an approved and registered treatment for sarcomas confined to the limbs in Europe since 1998, with limb salvage indexes of 76%. TNF improves drug distribution in solid tumours and secondarily destroys the tumour-associated vasculature (TAV). Here we explore the synergistic antitumour effect of another vasoactive agent, histamine (Hi), in doxorubicin (DXR)-based ILP and evaluate its antivascular effects on TAV. We used our well-established rat ILP model for in vivo studies looking at tumour response, drug distribution and effects on tumour vessels. In vitro studies explored drug interactions at cellular level on tumour cells (BN-175) and Human umbilical vein endothelial cells (HUVEC). There was a 17% partial response and a 50% arrest in tumour growth when Hi was combined to DXR, without important side effects, against 100% progressive disease with DXR alone and 29% arrest in tumour growth for Hi alone. Histology documented an increased DXR leakage in tumour tissue combined to a destruction of the TAV, when Hi was added to the ILP. In vitro no synergy between the drugs was observed. In conclusion, Hi is a vasoactive drug, targeting primarily the TAV and synergises with different chemotherapeutic agents.

Current and future treatment options for acne.

Acne is a frequent skin disease with abnormalities in the process of keratinization, sebaceous gland functioning and inflammation. In this review, our understanding of the pathogenesis of acne has been updated. An overview of efficacy and side effects of available anti-acne treatments is presented. Based on the present overview a recommendation for the treatment of various manifestations of acne is provided, also reconciling beneficial combinations of treatments. It is attractive to speculate that the increased insight into the pathogenesis of acne will create new treatment options. Challenging new options comprise blue light, photodynamic therapy, retinoic acid metabolism blocking agents and inhibitors of Th-1 cytokines.

Vocal tract resonance analysis of aging voice using long-term average spectra.

This study is the first to use long-term average spectra (LTAS) to investigate resonance characteristics of dynamic speech in young adulthood and old age. A total of 80 speakers participated, divided equally by age group and gender. All elderly speakers were healthy, active members of the community. Measurement of the first three spectral peaks in LTAS from the first paragraph of the Rainbow Passage revealed significant lowering of peak 1 from young adulthood to old age in both men and women. Peaks 2 and 3 also lowered significantly across the adult lifespan in women and showed a tendency to lower in men. These acoustic findings are consistent with anatomic data suggesting that aging results in lengthening of the supraglottic vocal tract. Findings that women demonstrate more substantial lowering of spectral peaks with aging than men suggest that women may undergo more pronounced age-related lengthening of the supraglottic vocal tract. Alternatively, it is possible that elderly men systematically alter tongue position during vowel articulation while elderly women are less inclined to do so. Taken in conjunction with previous research, these findings suggest a "mixed model" of vocal tract resonance changes with aging in which an interaction exists between gender, the resonance effects of laryngeal lowering, and vowel articulatory patterns.

Information about over-the-counter medication: the role of the pharmacy.

With regard to the proper use of over-the-counter drugs (OTCs), the importance of drug information has been stressed many times and a counseling role for the pharmacist is becoming more widely recognized. A community pharmacy was studied to determine what kind of information was given about OTCs and subsequently whether this information was adjusted to the informational needs of the patient. We observed 80 pharmacy-patient contacts concerning OTCs and interviewed these patients at home some days afterwards. Drug information was given both verbally and in writing by means of a patient package insert (36% and 63% of the purchases, respectively). In most instances information was provided even though not requested by the patients. When interviewed at home, patients said they were satisfied with the information received. It appeared that the information provided in the pharmacy was adjusted to the informational needs of the persons who use OTCs. Only when asked about the information concerning the use of OTCs in general, did patients' informational needs and drug informing behavior seem to be greater. This discrepancy between the study results is being discussed. The study findings suggest that a patient package insert is an important information source for patients at the moment they use OTCs, and therefore has to be delivered consistently. Further, the fact that the patients seldom asked for drug information at the pharmacy increases the importance of providing patient package inserts.