Transition Barrier Research Articles

PDB72 Challenges and Barriers during Transition of Type 1 Diabetic Patients from Pediatric into Adult Care in Armenia

Recent years a number of interventions are developed and implemented in some couintries to support young patients’ transition into adult clinics. There is no any transition clinic for type 1 diabetes in Armenia to provide smooth and adequate transition of diabetics from pediatric into adult care. The transition is provided automatically after the patients get 18 years old. In this regard we have prepared a questionnaire for patients to reveal the difficulties and disadvantages of this mandatory transition in health care structure of Armenia. 48 type 1 diabetic young patients, aged >18years old, were asked to fill in the questionnaire about their transition from pediatric to adult care. Their pediatric data of last mean HbA1c before transition was recorded from the pediatric endocrinology clinic and compared with current mean HbA1c (after transition). Statistical analyses were performed to determine the significance of findings. In all cases null hypothesis was rejected if p<0.05. Male/female ratio of respondents was as 26/22, and the mean age was 24±1.2. 93.75% of respondents mentioned measurement of HbA1c once a year after transition versus 3-4 times per year in pediatric clinic(p<0.05). Mean HbA1c was 11.3±0.45 versus the mean HbA1c before their transition 9.82±0.36(p<0.05). Respondents mentioned emotional and psychosocial barriers of transition: 87.5%(N=42)-less trust to adult care provider, and 37.5%(N=18)-low self-responsibility. As a major challenge 39.6%(N=19) patients mentioned low expertise of adult care providers, and 22.9%(N=11)-low financial support in adult health care system. Interestingly, 93.75%(N=45) of respondents highlighted the need of transition care coordinator between pediatric and adult providers. Current work highlights the need of a transition clinic (coordinating unit) for transferring of type 1 diabetics from pediatric into adult care in Armenia, aiming to a better engagement of both pediatric and adult care providers, and to improve the diabetes control and psychosocial environment of young diabetic patients.

Thermionic emission or tunneling? The universal transition electric field for ideal Schottky reverse leakage current: A case study in β -Ga2O3

The reverse leakage current through a Schottky barrier transitions from a thermionic emission-dominated regime to a barrier tunneling-dominated regime as the surface electric field increases. In this study, we evaluate such a transition electric field (ET) in β-Ga2O3 using a numerical reverse leakage model. ET is found to depend on temperature but has an extremely weak dependence on the doping concentration and the barrier height; as a result, a simple empirical expression can be derived to capture this near-universal dependence of ET on temperature. With the help of a field-plate design, we observed experimentally in lightly doped Ga2O3 Schottky barrier diodes near-ideal bulk reverse leakage characteristics, which match well with our numerical model and that confirm the presence of the transition region. Near the transition electric field, both thermionic emission and barrier tunneling should be considered. This study provides important guidance toward accurate design and modeling of Schottky barrier diodes, which can be readily extended to other semiconductors.

Optical subpicosecond nonvolatile switching and electron-phonon coupling in ferroelectric materials

Direct optical ferroelectric switching (FE switch) has the advantage of being ultrafast over the traditional FE switch, which relies on domain nucleation and growth. However, how to realize nonvolatility in such an optical FE switch poses a serious challenge. Time-dependent density-functional theory molecular dynamics study reveals that subpicosecond nonvolatile FE switches can be realized in GeTe and ${\mathrm{PbTiO}}_{3}$. While optical tuning of the transition barrier and initiation of a directional atomic motion are crucial, the dephasing of the excited state holds the key for the realization of nonvolatility.

Investigating barriers to circular supply chain in the textile industry from Stakeholders’ perspective

ABSTRACT The objectives of this study are to understand the circular supply chain barriers for textile companies to implement the circular economy. Main contributions of the study were to propose a specific framework that reveals circular supply chain barriers in transition to circular economy with holistic view by encompassing all stakeholders, to reveal causal relationships among the circular supply chain barriers within textile industry. Causal relationships between the proposed circular supply chain barriers were identified by Fuzzy-Decision Making Trial and Evaluation Laboratory (DEMATEL) method. The barriers are classified under cause and effect groups and related implications are proposed. The findings of this study are lack of collecting, sorting and recycling, reluctance for acceptance of CE model, and problems related to uniformity and standardisation are revealed as the most important barriers, respectively. Moreover, lack of technical knowledge is the most influencing factor, whereas, challenges in product design is the most influenced factor.

The structure evolution of titanium–vacancy complex in a vanadium-based alloy

Under irradiation conditions, excess point defects interact strongly with the solute atoms in fusion reactor materials. The solutes can bind with point defects and form clusters such as solute–vacancy complexes. The evolution of these complexes at long timescale significantly influences the mechanical properties of the irradiated materials. In this study, we mainly use climbing image nudged elastic band method to investigate the evolution and migration of titanium–vacancy complexes in a vanadium-based alloy. The transition pathways associated with atomic trajectories of complex evolution in bulk and in grain boundary vicinity are calculated. Results show that both basin energies and transition barriers are affected when a complex is in grain boundary vicinity. The evolution is revealed to be driven by multiple titanium–vacancy interactions synergistically. The migration is supposed to be induced by two mechanisms: the vacancy reorientation jumps and complex dissociation–reformation which are both based on titanium–vacancy interactions. This research contributes to the understanding of solute diffusion and early-stage radiation defects in vanadium-based alloys.

Electrically switchable hidden spin polarization in antiferroelectric crystals

Hidden spin polarization (HSP) emerges in centrosymmetric crystals where visible spin splittings in the real space can be observed because of the lack of inversion symmetry in each local sector. Starting from tight-binding models, we introduce nonsymmorphic antiferroelectric (AFE) crystals as a new class of functional materials that can exhibit strong local spin polarization. Such AFE crystals can be basically classified as in-plane and out-of-plane AFE configurations, and can be reversibly switched to the ferroelectric phase by an electric field to manifest global spin splittings, enabling a nonvolatile electrical control of spin-dependent properties. Based on first-principle calculations, we predict the realization of strong HSP in the AFE phase of a newly-discovered two-dimensional materials, quintuple-layer (QL) LiBiO$_2$. Furthermore, the spontaneous electric polarization ($\sim$ 0.3 nC/m) and the transition barrier as well as the tunable spin polarization of QL-LiBiO$_2$ are discussed.

Studying the Transition towards a Circular Bioeconomy—A Systematic Literature Review on Transition Studies and Existing Barriers

The European Commission’s strategic long-term vision for 2050, “A Clean Planet for All”, identifies the bioeconomy and the circular economy as key strategic areas for achieving a climate-neutral economy. Focus is given to the sustainability of biomass and the circularity of materials. However, in order to facilitate the transition toward a sustainable bio-based circular economy and to unlock its potential, strong accompanying measures are required. These should be designed based on a systematic understanding of transition drivers and barriers. This paper, after providing a systematic review of transition research on the circular bioeconomy, focuses on the identification and classification of transition barriers, clustering them into relevant categories. Moreover, it provides a comparison of the barriers identified by various frameworks.

A first principles investigation of the hydrogen-strain synergy on the formation and phase transition of hydrides in zirconium

The precipitation of hydrides phases is known to be a source of embrittlement in zirconium and its alloys. In the present work, the effects of hydrogen (H) in the bulk of Zirconium (Zr) systems has been investigated using density functional theory (DFT). A model for the nucleation of hydrides in terms of the thermodynamic and strain conditions has been determined from the examination of interstitial H configurations in hcp-Zr (α-Zr). We found that several coherent hcp structures for Zr2H have similar formation energies and structural properties, and thus are relatively easy to form. A number of Zr2H hydrides with hcp structures were found to be dynamically unstable, and were found to promote a phase transformation to the fcc lattice. Based on the hydrogen distribution, the orientation relationship and the strain conditions, the transition of Zr2H hydrides from the hexagonal to cubic phases have been determined. Our results suggest that hydrogen plays a fundamental role, since a substantial rearrangement is required to promote the hcp→fcc transformation of hydrides phases. We determined that a hcp→fcc transformation of the Zr host lattice is assisted by the lower barrier for phase transition in Zr2H compared to that of pure α-Zr. Thus, leading to the formation of the brittle δ hydride phase. The reported formation mechanisms of hydrides provide the basis to understand the precipitation of hydrides observed experimentally.

A Gd@C82 single-molecule electret.

Electrets are dielectric materials that have a quasi-permanent dipole polarization. A single-molecule electret is a long-sought-after nanoscale component because it can lead to miniaturized non-volatile memory storage devices. The signature of a single-molecule electret is the switching between two electric dipole states by an external electric field. The existence of these electrets has remained controversial because of the poor electric dipole stability in single molecules. Here we report the observation of a gate-controlled switching between two electronic states in Gd@C82. The encapsulated Gd atom forms a charged centre that sets up two single-electron transport channels. A gate voltage of ±11 V (corresponding to a coercive field of ~50 mV Å-1) switches the system between the two transport channels with a ferroelectricity-like hysteresis loop. Using density functional theory, we assign the two states to two different permanent electrical dipole orientations generated from the Gd atom being trapped at two different sites inside the C82 cage. The two dipole states are separated by a transition energy barrier of 11 meV. The conductance switching is then attributed to the electric-field-driven reorientation of the individual dipole, as the coercive field provides the necessary energy to overcome the transition barrier.

Efficient and Stable All‐Inorganic Perovskite Solar Cells

The large‐scale commercial application of organic–inorganic hybrid perovskite solar cells (PSCs) based on organic hole transport material (HTM) is still hindered by poor long‐term operational stability, although a certified record power conversion efficiency (PCE) as high as 25.2% can be achieved. In the recent several years, all‐inorganic PSCs have received tremendous attention due to their superb thermal and moisture stability and considerable progresses have been witnessed. Herein, the recent advancements of all‐inorganic PSCs are reviewed comprehensively. First, the recent progresses of the strategies for stabilizing the black phase of inorganic perovskites through either increasing tolerance factor or enhancing the energy barrier of phase transition from black to yellow phase are summarized and discussed. Second, the deposition and growth techniques of inorganic perovskite films are discussed. Third, the effective inorganic HTMs in normal all‐inorganic PSCs are described. Fourth, HTM‐free normal all‐inorganic PSCs are discussed. Afterward, the effective inorganic electron transport materials in inverted all‐inorganic PSCs are discussed. Subsequently, the advancements of interface engineering for increasing the PCE and stability of all‐inorganic PSCs are reviewed. Finally, a brief summary and outlook are presented to push up the PCE of all‐inorganic PSCs to over 20% in the near future.

Effect of thermally excited lattice vibrations on the thermodynamic stability of tungsten ditellurides WTe2 under high pressure: A first-principles investigation

The thermodynamic stability as a function of pressure and temperature of three WTe2 polytypes, i.e., Td, 1T′, and 2H phases, is examined using first-principles calculations, where the temperature-dependent contributions, arising particularly from the lattice vibrations, are derived from the quasiharmonic approximation. We find that the critical transition pressure to the 2H phase increases almost linearly with increasing temperature. Through the inspection of the phonon density of states, 2H-WTe2 is dynamically stable not only at high pressure, but also at zero pressure, indicating possible existence of 2H-WTe2 also at ambient conditions. On the other side, our results demonstrate that, at relevant temperature and pressure, the thermodynamic stability of 1T′-WTe2 is comparable to that of Td-WTe2, and further analysis reveals substantial similarities in terms of structural behavior between Td-WTe2 and 1T′-WTe2. These findings suggest not only that the two polytypes are likely to coexist in practical samples of WTe2 due probably to grains/regions either with tiny difference in stress, for example, or with different growth history, but also that the designation of 1T′, having been regularly used to described the compound under pressure in the literature, might actually be a mixture of Td and 1T′ polytypes, whose WTe2 layers laterally slide via low transition barrier induced probably by the applied pressure, resulting in the splitting of (101) and (113) peaks as observed in the diffraction experiments.

Barriers and facilitators for transitioning of young people from adolescent clinics to adult ART clinics in Uganda: unintended consequences of successful adolescent ART clinics

BackgroundThere is a growing number of adolescents and young adults living with HIV (YPLHIV) who require the transfer of care from pediatric/ adolescent clinics to adult Antiretroviral therapy (ART) clinics. A successful transition is critical for optimum health outcomes, yet facilities may lack infrastructure, human resources (with appropriate knowledge and skills), and a supportive environment, as only 3% of clinics in Uganda caring for YPLHIV have a process for supporting this critical transition from pediatric to adult care, and, facilitators and barriers of a successful transition are not well documented. The purpose of this study was to explore the facilitators and barriers of transitioning among adolescents from adolescent clinics to adult ART clinics.MethodEighteen focus group discussions were held in nine health facilities with 174 adolescents and YPLHIV to assess barriers and facilitators regarding transitioning to adult clinics. The focus group discussions were audio-recorded and transcribed. The Silences Framework using a thematic approach guided the analysis.ResultsThe key emerging issues were: Unfriendly adults in adult clinics, Care provided in the adolescent clinics, fear of stigma from health care providers, Congestion and long waiting time, fear to lose friends were barriers to transitioning. Transitioning preparation is key to a successful transition, moving as a cohort facilitates transition, and care in adult clinics offers new opportunities, could facilitate readiness and transition.ConclusionYPLHIV expressed fear to transition to adult clinics mainly because of the perceived better care provided in the adolescent clinic, thus constituting a barrier to smooth transition A range of individual, social and health system and services-related factors hindered transitioning. The expectation of transitioning as a group, assurance of similar care as in the adolescent clinic, and guarantees of confidentiality, privacy, and autonomy in decision-making for care was perceived as facilitators. Understanding barriers and facilitators can enable the Ministry of Health to improve the quality of life of YPLHIV through linkage to care, adherence, retention, and viral suppression. There is a need to better planning and preparation for clinical providers and YPLHIV with a focus on age-appropriate and individualized case management transition as well as focus on improving both clinical and psychosocial support throughout the process.

Validating the relationship between beginning students’ transitional challenges, well-being, help-seeking, and their adjustments in an Australian university

ABSTRACT To date, research has focussed on understanding how various contextual factors facilitate students’ adjustments to university as they begin their studies. However, there seems to be limited or no research and instruments that have specifically conceptualised and measured students’ adjustments, considering their transitional challenges, emotional wellbeing, and barriers to seeking help. Incorporating these factors, we previously developed a model of students’ adjustments, titled Transition, Wellbeing, Help-seeking and Adjustments (TWHAS). Building on this model, this paper aims to empirically validate the hypothesised TWHAS model using a validated survey and data collected from 306 first-year students transitioning to an Australian university. The strength of the predictive relations among the selected variables was tested by the significance of the path coefficients of the model. Our findings show a good fit to the theoretical model developed and demonstrate how students’ sociodemographic barriers to seeking help and moods (e.g. anxiety) can create a psychological barrier (e.g. lack of openness to seeking help) and how psychological barriers can further inhibit students’ overall adjustments to university. These findings have important implications for higher education policymakers, staff as well as administrators, counselling and support services future research on promoting students’ the positive adjustments to transition to university.

Visions, innovations, and justice? Transition contracts in Spain as policy mix instruments

Coal phasing-out policies and the consequent closure of large coal infrastructures (mines and thermal power plants) have put coal dependent areas at a crossroads. This empirical study applies the policy mix analytic framework to discuss how transition contracts, as new instruments in Spain, could accelerate socio-technological regime change and promote a just transition; all of which from the analysis of the barriers for the economic, political, social, technological and environmental spheres. From a mixed research design, information from 43 stakeholders was collected, first to qualify just transition barriers and then to quantify their relevance and intergroup variance. The resulting policy implications highlight three essential factors, a strategic vision, an innovation approach and a transversal notion of justice. These factors must be considered in order to increase consistency, coherence, comprehensiveness and credibility of transitional contracts.

Atomistic mechanism of stress modulated phase transition in monolayer MoTe[formula omitted

Monolayer MoTe2, one of the 2D transition metal dichalcogenide (TMD) materials, exhibits two stable structural phases: semiconducting 2H phase and metallic 1T′ phase. The dynamic control of the transition between these two phases on a single atomically thin sheet holds promise for a variety of revolutionary device applications. Particularity, stress could be utilized to dynamically modulate such phase transition. To date, the atomistic and kinetic mechanism of the phase transition under stress is not clear. In this paper, the finite deformation nudged elastic band method and density functional theory are applied to determine the phase transition barriers and pathways of monolayer MoTe2 as a function of applied stress. It is found that the stress can greatly influence the thermodynamics and kinetics of the phase nucleation and propagation. The results shed light on the phase engineering of 2D TMD materials with stress at the atomic level.

Functional Impact of the G279S Substitution in the Adenosine A1-Receptor (A1R-G279S7.44), a Mutation Associated with Parkinson’s Disease

In medium-size, spiny striatal neurons of the direct pathway, dopamine D₁- and adenosine A₁-receptors are coexpressed and are mutually antagonistic. Recently, a mutation in the gene encoding the A₁-receptor (A₁R), A₁R-G279S^7.44, was identified in an Iranian family: two affected offspring suffered from early-onset l-DOPA–responsive Parkinson’s disease. The link between the mutation and the phenotype is unclear. Here, we explored the functional consequence of the G279S substitution on the activity of the A₁-receptor after heterologous expression in HEK293 cells. The mutation did not affect surface expression and ligand binding but changed the susceptibility to heat denaturation: the thermodynamic stability of A₁R-G279S^7.44 was enhanced by about 2 and 8 K when compared with wild-type A₁-receptor and A₁R-Y288A^7.53 (a folding-deficient variant used as a reference), respectively. In contrast, the kinetic stability was reduced, indicating a lower energy barrier for conformational transitions in A₁R-G279S^7.44 (73 ± 23 kJ/mol) than in wild-type A₁R (135 ± 4 kJ/mol) or in A₁R-Y288A^7.53 (184 ± 24 kJ/mol). Consistent with this lower energy barrier, A₁R-G279S^7.44 was more effective in promoting guanine nucleotide exchange than wild-type A₁R. We detected similar levels of complexes formed between D₁-receptors and wild-type A₁R or A₁R-G279S^7.44 by coimmunoprecipitation and bioluminescence resonance energy transfer. However, lower concentrations of agonist were required for half-maximum inhibition of dopamine-induced cAMP accumulation in cells coexpressing D₁-receptor and A₁R-G279S^7.44 than in those coexpressing wild-type A₁R. These observations predict enhanced inhibition of dopaminergic signaling by A₁R-G279S^7.44 in vivo, consistent with a pathogenic role in Parkinson’s disease. <h3>SIGNIFICANCE STATEMENT</h3> Parkinson’s disease is caused by a loss of dopaminergic input from the substantia nigra to the caudate nucleus and the putamen. Activation of the adenosine A₁-receptor antagonizes responses elicited by dopamine D₁-receptor. We show that this activity is more pronounced in a mutant version of the A₁-receptor (A₁R-G279S^7.44), which was identified in individuals suffering from early-onset Parkinson’s disease.

Phase Transition Photodetection in Charge Density Wave Tantalum Disulfide.

The charge density wave (CDW) phase is a macroscopic quantum state with periodic charge density modulation accompanied by periodic lattice distortion in low-dimensional metals. External fields, such as an electric field and optical excitation, can trigger the transitions among different CDW states, leaving an under-explored mechanism and attracting great interest toward optoelectronic applications. Here, we explore a photoinduced phase transition in 1T-TaS2 under an electrical field. By analyzing the phase transition probability, we obtained a linear dependence of the phase transition barrier on the electric field and laser energy density. Additionally, the threshold laser energy for the phase transition decreases linearly with an increasing applied electrical field. Finally, picojoule photodetection was realized in the visible and near-infrared ranges near the CDW transition edge. Our work will promote the understanding of the CDW phase transition mechanism as well as open pathways for optoelectronic applications.

Dynamic behavior of OH and its atomic contrast with O adatom on the Ti site of TiO2(110) at 78 K by atomic force microscopy imaging

We experimentally observed the dynamic behavior of OH on the Ti site (OHt) of TiO2(110) at 78 K in detail by atomic force microscopy (AFM). OHt was imaged as a dimer shape or a fuzzy round shape corresponding to the motion of OHt that OHt swings along the [1–10] direction. The frequency of swing positively responds to the applied bias voltage between the tip and the sample, and it is proposed that the applied bias voltage decreases the barrier of the OHt transition between two or more equilibrium states. Such specific response of OHt to the applied bias voltage can be used as the fingerprint. In addition, the atomic contrast of O adatom (Oad) and OHt is compared with the contrast of other surface species by AFM, and it is demonstrated that the contrast of Oad and OHt is similar to the contrast of the surface defects due to the effect of tip apex polarity. H atom desorption of OHt is performed by Kelvin probe force spectroscopy, and it is resulted from the reduction of barrier width together with the tunneling electron excitation. The present study is expected to be useful to explore the property of H-involved species and the surface reactions on the oxide surface by AFM.

Functional Impact of the G279S Substitution in the Adenosine A1-Receptor (A1R-G279S7.44), a Mutation Associated with Parkinson's Disease.

In medium-size, spiny striatal neurons of the direct pathway, dopamine D1- and adenosine A1-receptors are coexpressed and are mutually antagonistic. Recently, a mutation in the gene encoding the A1-receptor (A1R), A1R-G279S7.44, was identified in an Iranian family: two affected offspring suffered from early-onset l-DOPA-responsive Parkinson's disease. The link between the mutation and the phenotype is unclear. Here, we explored the functional consequence of the G279S substitution on the activity of the A1-receptor after heterologous expression in HEK293 cells. The mutation did not affect surface expression and ligand binding but changed the susceptibility to heat denaturation: the thermodynamic stability of A1R-G279S7.44 was enhanced by about 2 and 8 K when compared with wild-type A1-receptor and A1R-Y288A7.53 (a folding-deficient variant used as a reference), respectively. In contrast, the kinetic stability was reduced, indicating a lower energy barrier for conformational transitions in A1R-G279S7.44 (73 ± 23 kJ/mol) than in wild-type A1R (135 ± 4 kJ/mol) or in A1R-Y288A7.53 (184 ± 24 kJ/mol). Consistent with this lower energy barrier, A1R-G279S7.44 was more effective in promoting guanine nucleotide exchange than wild-type A1R. We detected similar levels of complexes formed between D1-receptors and wild-type A1R or A1R-G279S7.44 by coimmunoprecipitation and bioluminescence resonance energy transfer. However, lower concentrations of agonist were required for half-maximum inhibition of dopamine-induced cAMP accumulation in cells coexpressing D1-receptor and A1R-G279S7.44 than in those coexpressing wild-type A1R. These observations predict enhanced inhibition of dopaminergic signaling by A1R-G279S7.44 in vivo, consistent with a pathogenic role in Parkinson's disease. SIGNIFICANCE STATEMENT: Parkinson's disease is caused by a loss of dopaminergic input from the substantia nigra to the caudate nucleus and the putamen. Activation of the adenosine A1-receptor antagonizes responses elicited by dopamine D1-receptor. We show that this activity is more pronounced in a mutant version of the A1-receptor (A1R-G279S7.44), which was identified in individuals suffering from early-onset Parkinson's disease.

Phase Engineering of Transition Metal Dichalcogenides with Unprecedentedly High Phase Purity, Stability, and Scalability via Molten-Metal-Assisted Intercalation.

The crystalline phase of layered transition metal dichalcogenides (TMDs) directly determines their material property. The most thermodynamically stable phase structures in TMDs are the semiconducting 2H and metastable metallic 1T phases. To overcome the low phase purity and instability of 1T-TMDs, which limits the utilization of their intrinsic properties, various synthesis strategies for 1T-TMDs have been proposed in phase-engineering studies. Herein, a facile and scalable synthesis of 1T-phase molybdenum disulfide (MoS2 ) via the molten-metal-assisted intercalation (MMI) approach is introduced, which exploits the capillary action of molten potassium and the difference between the electron affinity of MoS2 and the ionization potential of potassium. Highly reactive molten potassium metal can readily intercalate into the MoS2 interlayers, inducing an efficient phase transition from the 2H to 1T crystal structure. The ionic bonding between the intercalated potassium and sulfur lowers the energy barrier of the 1T-phase transition, enhancing the phase stability of the 1T crystals. Owing to the high purity and stability of the 1T phase, the electrocatalytic performance for the hydrogen evolution reaction is significantly higher in 1T-MoS2 (MMI) than in 2H-MoS2 and even in 1T-MoS2 synthesized using n-butyllithium.