Understanding MOF Flexibility: An Analysis Focused on Pillared Layer MOFs as a Model System.

Flexible porous frameworks are at the forefront of materials research. A unique feature is their ability to open and close their pores in an adaptive manner induced by chemical and physical stimuli. Such enzyme-like selective recognition offers a wide range of functions ranging from gas storage and separation to sensing, actuation, mechanical energy storage and catalysis. However, the factors affecting switchability are poorly understood. In particular, the role of building blocks, as well as secondary factors (crystal size, defects, cooperativity) and the role of host-guest interactions, profit from systematic investigations of an idealized model by advanced analytical techniques and simulations. The review describes an integrated approach targeting the deliberate design of pillared layer metal-organic frameworks as idealized model materials for the analysis of critical factors affecting framework dynamics and summarizes the resulting progress in their understanding and application.

Reduced thermal expansion by surface-mounted nanoparticles in a pillared-layered metal-organic framework.

Control of thermal expansion (TE) is important to improve material longevity in applications with repeated temperature changes or fluctuations. The TE behavior of metal-organic frameworks (MOFs) is increasingly well understood, while the impact of surface-mounted nanoparticles (NPs) on the TE properties of MOFs remains unexplored despite large promises of NP@MOF composites in catalysis and adsorbate diffusion control. Here we study the influence of surface-mounted platinum nanoparticles on the TE properties of Pt@MOF (Pt@Zn2(DP-bdc)2dabco; DP-bdc2-=2,5-dipropoxy-1,4-benzenedicarboxylate, dabco=1,4-diazabicyclo[2.2.2]octane). We show that TE is largely retained at low platinum loadings, while high loading results in significantly reduced TE at higher temperatures compared to the pure MOF. These findings support the chemical intuition that surface-mounted particles restrict deformation of the MOF support and suggest that composite materials exhibit superior TE properties thereby excluding thermal stress as limiting factor for their potential application in temperature swing processes or catalysis.

Interactive, case-based seminars in the digitized pediatrics block internship from the students' perspective.

We report on the pediatric block practice digitized due to the COVID-19 pandemic. Nineteen seminars were recorded, which represent the broad spectrum of pediatrics as comprehensively as possible, and made available on the learning platform ILIAS in a learning sequence. In order to increase attention and learning success formative questions were interspersed into the seminars. The evaluation of the students showed a high acceptance of this course. Especially the formative questions and the high time flexibility were appreciated. A major point of criticism was that not all questions were resolved immediately afterwards. The resolutions were inserted in the meantime. Parts of the digitized block practical course should therefore be used in the pediatric block practical course after the end of the corona restrictions after appropriate revision.

Transition from Homochiral Clusters to Racemate Monolayers during 2D Crystallization of Trioxa[11]helicene on Ag(100).

The front cover artwork is provided by Prof. Ernst from Empa. The image shows determination of the sense of helicity of trioxa[11]helicene enantiomers with an atomic force microscope, which allows discrimination between homo- and heterochiral 2D self-assembly. Read the full text of the Article at 10.1002/cphc.202000853.

Transition from Homochiral Clusters to Racemate Monolayers during 2D Crystallization of Trioxa[11]helicene on Ag(100).

The phenomenon of chiral crystallization into homochiral crystals is known for more than 170 years, yet it is still poorly understood. Studying crystallization on surfaces under well-defined condition seems a promising approach towards better understanding the intermolecular chiral recognition mechanisms during nucleation and growth. The two-dimensional aggregation of racemic trioxaundecahelicene on the single crystalline silver(100) surface has been investigated with scanning tunneling microscopy and with non-contact atomic force microscopy, as well as molecular modeling simulations. A transition from homochiral cluster motifs to heterochiral assembly into large islands with increasing coverage is observed. Force field modelling confirms higher stability of heterochiral arrangements from twelve molecules on. Results are discussed with respect to previous findings for the all-carbon heptahelicene on the same surface.

Thermal Defect Engineering of Precious Group Metal-Organic Frameworks: A Case Study on Ru/Rh-HKUST-1 Analogues.

A methodology is introduced for controlled postsynthetic thermal defect engineering (TDE) of precious group metal-organic frameworks (PGM-MOFs). The case study is based on the Ru/Rh analogues of the archetypical structure [Cu3(BTC)2] (HKUST-1; BTC = 1,3,5-benzenetricarboxylate). Quantitative monitoring of the TDE process and extensive characterization of the samples employing a complementary set of analytical and spectroscopic techniques reveal that the compositionally very complex TDE-MOF materials result from the elimination and/or fragmentation of ancillary ligands and/or linkers. TDE involves the preferential secession of acetate ligands, intrinsically introduced via coordination modulation during synthesis, and the gradual decarboxylation of ligator sites of the framework linker BTC. Both processes lead to modified Ru/Rh paddlewheel nodes. These nodes exhibit a lowered average oxidation state and more accessible open metal centers, as deduced from surface-ligand IR spectroscopy using CO as a probe and supported by density functional theory (DFT)-based computations. The monometallic and the mixed-metal PGM-MOFs systematically differ in their TDE properties and, in particular in the hydride generation ability (HGA). This latter property is an important indicator for the catalytic activity of PGM-MOFs, as demonstrated by the ethylene dimerization reaction to 1-butene.

Quantum dissipation driven by electron transfer within a single molecule investigated with atomic force microscopy.

Intramolecular charge transfer processes play an important role in many biological, chemical and physical processes including photosynthesis, redox chemical reactions and electron transfer in molecular electronics. These charge transfer processes are frequently influenced by the dynamics of their molecular or atomic environments, and they are accompanied with energy dissipation into this environment. The detailed understanding of such processes is fundamental for their control and possible exploitation in future technological applications. Most of the experimental studies of the intramolecular charge transfer processes so far have been carried out using time-resolved optical spectroscopies on large molecular ensembles. This hampers detailed understanding of the charge transfer on the single molecular level. Here we build upon the recent progress in scanning probe microscopy, and demonstrate the control of mixed valence state. We report observation of single electron transfer between two ferrocene redox centers within a single molecule and the detection of energy dissipation associated with the single electron transfer.

Understanding and improving value frameworks with real-world patient outcomes.

OBJECTIVES: To provide recommendations that will improve approaches to measuring the value of new medical technologies to patients. STUDY DESIGN: Informed discussion by experts after literature review. METHODS: A working group was formed, and participants discussed how value frameworks should incorporate key features important to patients in evaluating new medical technologies, particularly for chronic diseases. RESULTS: The working group suggests that new value frameworks should integrate real-world evidence to complement randomized controlled trials, incorporate the ways in which real-world behavior mediates outcomes, and explicitly discuss how therapies affect real-world equity and disparities in care. CONCLUSIONS: Collective stakeholders that include key decision makers within our healthcare system need to recognize the importance of implementing real-world evidence and devote resources to further research into the chronic disease areas in which the impact of human behavior is amplified by the duration of disease and treatment.

Large Converse Piezoelectric Effect Measured on a Single Molecule on a Metallic Surface.

The converse piezoelectric effect is a phenomenon in which mechanical strain is generated in a material due to an applied electrical field. In this work, we demonstrate the converse piezoelectric effect in single heptahelicene-derived molecules on the Ag(111) surface using atomic force microscopy (AFM) and total energy density functional theory (DFT) calculations. The force-distance spectroscopy acquired over a wide range of bias voltages reveals a linear shift of the tip-sample distance at which the contact between the molecule and tip apex is established. We demonstrate that this effect is caused by the bias-induced deformation of the spring-like scaffold of the helical polyaromatic molecules. We attribute this effect to coupling of a soft vibrational mode of the molecular helix with a vertical electric dipole induced by molecule-substrate charge transfer. In addition, we also performed the same spectroscopic measurements on a more rigid o-carborane dithiol molecule on the Ag(111) surface. In this case, we identify a weaker linear electromechanical response, which underpins the importance of the helical scaffold on the observed piezoelectric response.

Retrofit Weight-Loss Outcomes at 6, 12, and 24 Months and Characteristics of 12-Month High Performers: A Retrospective Analysis.

BACKGROUND: Obesity is the leading cause of preventable death costing the health care system billions of dollars. Combining self-monitoring technology with personalized behavior change strategies results in clinically significant weight loss. However, there is a lack of real-world outcomes in commercial weight-loss program research. OBJECTIVE: Retrofit is a personalized weight management and disease-prevention solution. This study aimed to report Retrofit's weight-loss outcomes at 6, 12, and 24 months and characterize behaviors, age, and sex of high-performing participants who achieved weight loss of 10% or greater at 12 months. METHODS: A retrospective analysis was performed from 2011 to 2014 using 2720 participants enrolled in a Retrofit weight-loss program. Participants had a starting body mass index (BMI) of >25 kg/m² and were at least 18 years of age. Weight measurements were assessed at 6, 12, and 24 months in the program to evaluate change in body weight, BMI, and percentage of participants who achieved 5% or greater weight loss. A secondary analysis characterized high-performing participants who lost ≥10% of their starting weight (n=238). Characterized behaviors were evaluated, including self-monitoring through weigh-ins, number of days wearing an activity tracker, daily step count average, and engagement through coaching conversations via Web-based messages, and number of coaching sessions attended. RESULTS: Average weight loss at 6 months was -5.55% for male and -4.86% for female participants. Male and female participants had an average weight loss of -6.28% and -5.37% at 12 months, respectively. Average weight loss at 24 months was -5.03% and -3.15% for males and females, respectively. Behaviors of high-performing participants were assessed at 12 months. Number of weigh-ins were greater in high-performing male (197.3 times vs 165.4 times, P=.001) and female participants (222 times vs 167 times, P<.001) compared with remaining participants. Total activity tracker days and average steps per day were greater in high-performing females (304.7 vs 266.6 days, P<.001; 8380.9 vs 7059.7 steps, P<.001, respectively) and males (297.1 vs 255.3 days, P<.001; 9099.3 vs 8251.4 steps, P=.008, respectively). High-performing female participants had significantly more coaching conversations via Web-based messages than remaining female participants (341.4 vs 301.1, P=.03), as well as more days with at least one such electronic message (118 vs 108 days, P=.03). High-performing male participants displayed similar behavior. CONCLUSIONS: Participants on the Retrofit program lost an average of -5.21% at 6 months, -5.83% at 12 months, and -4.09% at 24 months. High-performing participants show greater adherence to self-monitoring behaviors of weighing in, number of days wearing an activity tracker, and average number of steps per day. Female high performers have higher coaching engagement through conversation days and total number of coaching conversations.

How drug life-cycle management patent strategies may impact formulary management.

Drug manufacturers may employ various life-cycle management patent strategies, which may impact managed care decision making regarding formulary planning and management strategies when single-source, branded oral pharmaceutical products move to generic status. Passage of the Hatch-Waxman Act enabled more rapid access to generic medications through the abbreviated new drug application process. Patent expirations of small-molecule medications and approvals of generic versions have led to substantial cost savings for health plans, government programs, insurers, pharmacy benefits managers, and their customers. However, considering that the cost of developing a single medication is estimated at $2.6 billion (2013 dollars), pharmaceutical patent protection enables companies to recoup investments, creating an incentive for innovation. Under current law, patent protection holds for 20 years from time of patent filing, although much of this time is spent in product development and regulatory review, leaving an effective remaining patent life of 7 to 10 years at the time of approval. To extend the product life cycle, drug manufacturers may develop variations of originator products and file for patents on isomers, metabolites, prodrugs, new drug formulations (eg, extended-release versions), and fixed-dose combinations. These additional patents and the complexities surrounding the timing of generic availability create challenges for managed care stakeholders attempting to gauge when generics may enter the market. An understanding of pharmaceutical patents and how intellectual property protection may be extended would benefit managed care stakeholders and help inform decisions regarding benefit management.

Graphene on SiC(0001) inspected by dynamic atomic force microscopy at room temperature.

We investigated single-layer graphene on SiC(0001) by atomic force and tunneling current microscopy, to separate the topographic and electronic contributions from the overall landscape. The analysis revealed that the roughness evaluated from the atomic force maps is very low, in accord with theoretical simulations. We also observed that characteristic electron scattering effects on graphene edges and defects are not accompanied by any out-of-plane relaxations of carbon atoms.

Force-Driven Single-Atom Manipulation on a Low-Reactive Si Surface for Tip Sharpening.

A single atomic manipulation on the delta-doped B:Si(111)-(√3x√3)R30° surface using a low temperature dynamic atomic force microscopy based on the Kolibri sensor is investigated. Through a controlled vertical displacement of the probe, a single Si adatom in order to open a vacancy is removed. It is shown that this process is completely reversible, by accurately placing a Si atom back into the vacancy site. In addition, density functional theory simulations are carried out to understand the underlying mechanism of the atomic manipulation in detail. This process also rearranges the atoms at the tip apex, which can be effectively sharpened in this way. Such sharper tips allow for a deeper look into the Si adatom vacancy site. Namely, high-resolution images of the vacancy showing subsurface Si dangling bond triplets, which surround the substitutional B dopant atom in the first bilayer, are achieved.

Arm and neck pain in ultrasonographers.

OBJECTIVE: The aim of this study was to evaluate the prevalence of upper-body-quadrant pain among ultrasonographers and to evaluate the association between individual ergonomics, musculoskeletal disorders, and occurrence of neck pain. METHOD: A hundred and ten (N = 110) Belgian and Dutch male and female hospital ultrasonographers were consecutively enrolled in the study. Data on work-related ergonomic and musculoskeletal disorders were collected with an electronic inquiry, including questions regarding ergonomics (position of the screen, high-low table, and ergonomic chair), symptoms (neck pain, upper-limb pain), and work-related factors (consecutive working hours a day, average working hours a week). RESULTS: Subjects with the screen on their left had significantly more neck pain (odds ratio [OR] = 3.6, p = .0286). Depending on the workspace, high-low tables increased the chance of developing neck pain (OR = 12.9, p = .0246). A screen at eye level caused less neck pain (OR = .22, p = .0610). Employees with a fixed working space were less susceptible to arm pain (OR = 0.13, p = .0058). The prevalence of arm pain was significantly higher for the vascular department compared to radiology, urology, and gynecology departments (OR = 9.2, p = .0278). CONCLUSIONS: Regarding prevention of upper-limb pain in ultrasonograph, more attention should be paid to the work environment and more specialty to the ultrasound workstation layout. Primary ergonomic prevention could provide a painless work situation for the ultrasonographer. APPLICATION: Further research on the ergonomic conditions of ultrasonography is necessary to develop ergonomic solutions in the work environment that will help to alleviate neck and arm pain.

Increasing the medium-term clinical benefits of hospital-based cardiac rehabilitation by physical activity telemonitoring in coronary artery disease patients.

BACKGROUND: The purpose of this study was to evaluate the effect of a physical activity telemonitoring program on daily physical activity level, oxygen uptake capacity (VO(2peak)), and cardiovascular risk profile in coronary artery disease (CAD) patients who completed phase II cardiac rehabilitation (CR). METHODS: Eighty CAD patients who completed phase II CR were randomly assigned to an additional telemonitoring intervention or standard CR. The patients in the intervention group (n = 40) wore a motion sensor continuously for 18 weeks. Each week these patients received a step count goal, with the aim to gradually increase the patients' physical activity level. In the control group (n = 40), the patients wore an unreadable motion sensor for seven days for measurement purposes only (at start of follow-up, and after six and 18 weeks). At start of follow-up and after 18 weeks blood lipid profile, glycemic control, waist circumference and body mass index was assessed. VO(2peak) was assessed at start of follow-up, and after six and 18 weeks. Re-hospitalisation rate was followed during this timeframe. RESULTS: In the intervention group, VO(2peak) increased significantly during follow-up (P = 0.001), in the control group it did not (P = 0.273). A significant correlation was found between daily aerobic step count and improvement in VO(2peak) (P = 0.030, r = 0.47). Kaplan-Meier curve analysis showed a trend towards fewer re-hospitalisations for patients in the telemonitoring group (P = 0.09). CONCLUSIONS: The study showed that, to maintain exercise tolerance and lower re-hospitalisation rate after hospital-based CR in CAD patients, a physical activity telemonitoring program might be an effective intervention.

Increasing preventive health services via tailored health communications.

OBJECTIVES: To develop a methodology that stratifies members by likelihood of completing a colorectal cancer screening (CRCS). Such information can guide the communication development and the allocation of resources for tailored communication outreaches. STUDY DESIGN: Prospective study of an insured commercial population that includes randomized assignments to a control group or a treatment group for communication interventions. METHODS: A total of 46,697 members overdue (nonadherent based on available administrative data) for a CRCS were assigned to 1 of 5 graded segments as part of an interactive voice response (IVR) call. Another 400 members per outreach segment were randomly assigned to a control group and received no communication. Primary outcome: receipt of CRCS (assessed Healthcare Effectiveness Data and Information Set [HEDIS] summary data, 3 months after IVR) for each graded segment within the control and the intervention groups. Secondary outcomes: association between the CRCS rates and the identified segments; communication cost per completed screening. RESULTS: Primary outcome: 1971 members completed the screening. Screening rates for the 5 graded segments were 2.4%, 3.6%, 5.0%, 7.2%, and 8.0%. Secondary outcome: c2 proportions test a significant association between the segment groups and the CRCS completion rates. The association between segment and screening rates follow the expected predicted range in both the intervention and holdout groups. Communication cost per screening: $14.84. CONCLUSIONS: Segmenting members by variables that are associated with CRCS completion identified graded segments that completed the CRCSs at different rates. Tailored interventions can be developed to promote a health service for each segment. The segmentation approach proves to be beneficial.

Research to real-world application: experts weigh in on the underuse of anticoagulants.

Although numerous studies have shown that anticoagulants can reduce the risk of stroke and thromboembolic events in patients with nonvalvular atrial fibrillation, they are underprescribed in the clinical setting. While standardized risk scoring assessments are recommended in treatment guidelines to determine when anticoagulant use may be appropriate, they are not widely used in the real-world clinical setting. Many factors contribute to anticoagulant underuse, including patient characteristics and comorbidities. Reluctance to prescribe an anticoagulant may also stem from concerns about bleeding or other perceived risks. In addition, physicians may be discouraged from prescribing anticoagulant therapy, particularly warfarin, if follow-up care and monitoring is potentially unfeasible. Patient fears of treatment and lack of access to the healthcare system also contribute to underuse. Increased awareness and education, medical therapy management programs, better care coordination, and improvements in monitoring and follow-up programs may help to increase the use of anticoagulant therapies in appropriate patients.

Characterization of the mechanical properties of qPlus sensors.

In this paper we present a comparison of three different methods that can be used for estimating the stiffness of qPlus sensors. The first method is based on continuum theory of elasticity. The second (Cleveland's method) uses the change in the eigenfrequency that is induced by the loading of small masses. Finally, the stiffness is obtained by analysis of the thermal noise spectrum. We show that all three methods give very similar results. Surprisingly, neither the gold wire nor the gluing give rise to significant changes of the stiffness in the case of our home-built sensors. Furthermore we describe a fast and cost-effective way to perform Cleveland's method. This method is based on gluing small pieces of a tungsten wire; the mass is obtained from the volume of the wire, which is measured by optical microscopy. To facilitate detection of oscillation eigenfrequencies under ambient conditions, we designed and built a device for testing qPlus sensors.