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2.
Oncol Res Treat ; 2024 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-38484712

RESUMO

In the context of the COVID-19 pandemic, there has been a scarcity of resources with various effects on the care of cancer patients. This paper provides an English summary of a German guideline on prioritization and resource allocation for colorectal and pancreatic cancer in the context of the pandemic. Based on a selective literature review as well as empirical and ethical analyses, the research team of the CancerCOVID Consortium drafted recommendations for prioritizing diagnostic and treatment measures for both entities. The final version of the guideline received consent from the executive boards of nine societies of the Association of Scientific Medical Societies in Germany (AWMF), 20 further professional organizations and 22 other experts from various disciplines as well as patient representatives. The guiding principle for the prioritization of decisions is the minimization of harm. Prioritization decisions to fulfill this overall goal should be guided by 1. the urgency relevant to avoid or reduce harm; 2. the likelihood of success of the diagnostic or therapeutic measure advised; and 3. the availability of alternative treatment options. In the event of a relevant risk of harm as a result of prioritization, these decisions should be made by means of a team approach. Gender, age, disability, ethnicity, origin and other social characteristics, such as social or insurance status, as well as the vehemence of a patient's treatment request and SARS-CoV-2 vaccination status should not be used as prioritization criteria. The guideline provides concrete recommendations for 1. diagnostic procedures, 2. surgical procedures for cancer, and 3. systemic treatment and radiotherapy in patients with colorectal or pancreatic cancer within the context of the German healthcare system.

3.
Eur Spine J ; 33(1): 19-30, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37971536

RESUMO

PURPOSE: In spine care, frailty is associated with poor outcomes. The aim of this study was to describe changes in frailty in spine care during the coronavirus disease 2019 (COVID-19) pandemic and their relation to surgical management and outcomes. METHODS: Patients hospitalized for spine pathologies between January 1, 2019, and May 17, 2022, within a nationwide network of 76 hospitals in Germany were retrospectively included. Patient frailty, types of surgery, and in-hospital mortality rates were compared between pandemic and pre-pandemic periods. RESULTS: Of the 223,418 included patients with spine pathologies, 151,766 were admitted during the pandemic and 71,652 during corresponding pre-pandemic periods in 2019. During the pandemic, the proportion of high-frailty patients increased from a range of 5.1-6.1% to 6.5-8.8% (p < 0.01), while the proportion of low frailty patients decreased from a range of 70.5-71.4% to 65.5-70.1% (p < 0.01). In most phases of the pandemic, the Elixhauser comorbidity index (ECI) showed larger increases among high compared to low frailty patients (by 0.2-1.8 vs. 0.2-0.8 [p < 0.01]). Changes in rates of spine surgery were associated with frailty, most clearly in rates of spine fusion, showing consistent increases among low frailty patients (by 2.2-2.5%) versus decreases (by 0.3-0.8%) among high-frailty patients (p < 0.02). Changes in rates of in-hospital mortality were not associated with frailty. CONCLUSIONS: During the COVID-19 pandemic, the proportion of high-frailty patients increased among those hospitalized for spine pathologies in Germany. Low frailty was associated with a rise in rates of spine surgery and high frailty with comparably larger increases in rates of comorbidities.


Assuntos
COVID-19 , Fragilidade , Humanos , Fragilidade/epidemiologia , Fragilidade/complicações , Pandemias , Estudos Retrospectivos , Alemanha/epidemiologia
4.
J Neurol Surg A Cent Eur Neurosurg ; 84(1): 58-64, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35760290

RESUMO

BACKGROUND: The full impact of the COVID-19 pandemic on surgical spine care is difficult to assess due to a lack in nationwide evidence from more recent phases of the pandemic. We aimed to describe changes in in-hospital processes associated with spinal fusion procedures in the treatment of spinal infections (SI) during different phases of the pandemic. METHODS: In this retrospective observational study, we examined the in-hospital prevalence and outcomes of spinal fusion procedures for SI (along with patient characteristics, rates of transfer to intensive care units, and mortality rates) during the first four waves of the pandemic compared with the corresponding prepandemic periods in 2019. We used administrative data from a nationwide network of 76 hospitals managing 7% of all in-hospital cases in Germany. RESULTS: We observed no significant change in the prevalence of SI fusion procedures during the pandemic, neither in total numbers (349 vs. 373) nor for each wave separately. On a patient level, we found no differences in age, sex, and the prevalence of paresis, and no relevant differences in associated comorbidities. The rate of mechanical ventilation did not change during any of the examined pandemic waves: it ranged between 9.5 and 18.6% during the pandemic and 3.1 and 16.0% during the corresponding prepandemic control periods. The rate of transfer to intensive care changed only during wave 4 (from 70.4 to 54.8%; p = 0.046) but not in any other pandemic phases. We observed no changes in in-hospital mortality rates (range: 2.9-9.7% vs. 6.2-11.3%) or in duration of hospital stay (range: 26.2-30.8 days vs. 20.8-29.2 days). CONCLUSIONS: The main finding of our study is that within this nationwide network of spine care centers in Germany, the delivery of surgical treatment of SI by means of spinal fusion procedures was maintained throughout the first four waves of the pandemic. Furthermore, there were no relevant changes in patient demographics, in-hospital processes, and mortality rates.


Assuntos
COVID-19 , Fusão Vertebral , Humanos , Fusão Vertebral/métodos , COVID-19/epidemiologia , Pandemias , Hospitais , Estudos Retrospectivos , Vértebras Cervicais/cirurgia
5.
Support Care Cancer ; 29(2): 965-973, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32556715

RESUMO

PURPOSE: To determine the efficacy of specifically targeted interventions in palliative care, sequential use of the Demoralization Scale (DS) could be a useful approach. This study's main objective was to evaluate the weekly use of the DS for palliative care inpatients. Secondary objectives were the analysis of the DS, self-perceived strain, and personal benefits of the assessment. METHODS: Patients admitted to 3 palliative care units (PCUs) were tested for eligibility and asked to complete the DS weekly. Self-perceived strain was rated on a numeric scale (0-10). Open questions about strain and helpfulness of the survey were asked. RESULTS: Over 10 months, 568 patients were admitted to the PCUs; 193 patients were eligible. A total of 120 patients participated once, of whom only 41 (34.1%) participated at least twice. The mean self-perceived strain caused by the assessment was 1.53 at T1 (N = 117, SD = 2.27, max = 8). CONCLUSIONS: While the single use of the DS in PCUs seems justified in view of the possibility to detect severe demoralization with overall low to moderate strain and self-perceived helpfulness for patients, the feasibility of the sequential use of the DS has to be regarded critically. Our study undermines the complexity of assessing changes in self-reported psychological phenomena with end-of-life patients at a PCU. The most limiting factors for participating twice were that patients were either discharged from hospital or declined further participation.


Assuntos
Morte , Desmoralização , Cuidados Paliativos/psicologia , Psicometria/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Adulto Jovem
7.
J Palliat Med ; 22(11): 1378-1385, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31210558

RESUMO

Context: Internationally, a variety of reimbursement systems exists for palliative care (PC). In Germany, PC units (PCUs) may choose between per-diem rates and diagnosis-related groups (DRGs). Both systems are controversially discussed. Objectives: To explore the experiences and views of German PCU clinicians and experts for PCU financing regarding per-diem rates and DRGs as reimbursement systems with a focus on (1) cost coverage, (2) strengths and weaknesses of both financing systems, and (3) options for further development of funding PCUs. Design: Qualitative semistructured interviews with PCU clinicians and experts for PCU financing, analyzed by thematic analysis using the Framework approach. Setting/Subjects/Measurements: Ten clinicians and 13 experts for financing were interviewed June-October 2015 on both reimbursement systems for PCU. Results: Interviewees had divergent experiences with both reimbursement systems regarding cost coverage. A described strength of per-diem rates was the perceived possibility of individual care without direct financial pressure. The nationwide variation of per-diem rates and the lack of quality standards were named as weaknesses. DRGs were criticized for incentives perceived as perverse and inadequate representation of PC-specific procedures. However, the quality standards for PCUs required within the German DRG system were described as important strength. Suggestions for improvement of the funding system pointed toward a combination of per-diem rates with a grading according to disease severity/complexity of care. Conclusions: Expert opinions suggest that neither current DRGs nor per-diem rates are ideal for funding of PCUs. Suggested improvements regarding adequate funding of PCUs resemble and supplement international developments.


Assuntos
Pacientes Internados , Reembolso de Seguro de Saúde , Cuidados Paliativos/economia , Mecanismo de Reembolso , Grupos Diagnósticos Relacionados/economia , Feminino , Alemanha , Humanos , Entrevistas como Assunto , Masculino , Pesquisa Qualitativa
8.
BMC Health Serv Res ; 19(1): 157, 2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30866912

RESUMO

BACKGROUND: The concept of complexity is used in palliative care (PC) to describe the nature of patients' situations and the extent of resulting needs and care demands. However, the term or concept is not clearly defined and operationalised with respect to its particular application in PC. As a complex problem, a care situation in PC is characterized by reciprocal, nonlinear relations and uncertainties. Dealing with complex problems necessitates problem-solving methods tailored to specific situations. The theory of complex adaptive systems (CAS) provides a framework for locating problems and solutions. This study aims to describe criteria contributing to complexity of PC situations from the professionals' view and to develop a conceptual framework to improve understanding of the concept of "complexity" and related elements of a PC situation by locating the complex problem "PC situation" in a CAS. METHODS: Qualitative interview study with 42 semi-structured expert (clinical/economical/political) interviews. Data was analysed using the framework method. The thematic framework was developed inductively. Categories were reviewed, subsumed and connected considering CAS theory. RESULTS: The CAS of a PC situation consists of three subsystems: patient, social system, and team. Agents in the "system patient" are allocated to further subsystems on patient level: physical, psycho-spiritual, and socio-cultural. The "social system" and the "system team" are composed of social agents, who affect the CAS as carriers of characteristics, roles, and relationships. Environmental factors interact with the care situation from outside the system. Agents within subsystems and subsystems themselves interact on all hierarchical system levels and shape the system behaviour of a PC situation. CONCLUSIONS: This paper provides a conceptual framework and comprehensive understanding of complexity in PC. The systemic view can help to understand and shape situations and dynamics of individual care situations; on higher hierarchical level, it can support an understanding and framework for the development of care structures and concepts. The framework provides a foundation for the development of a model to differentiate PC situations by complexity of patients and care needs. To enable an operationalisation and classification of complexity, relevant outcome measures mirroring the identified system elements should be identified and implemented in clinical practice.


Assuntos
Cuidados Paliativos/organização & administração , Cultura , Feminino , Pessoal de Saúde/estatística & dados numéricos , Humanos , Masculino , Avaliação das Necessidades , Cuidados Paliativos/psicologia , Pesquisa Qualitativa , Fatores Socioeconômicos , Espiritualidade
9.
Data Brief ; 19: 1549-1555, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30229027

RESUMO

In the last decades, much attention was given to mechanical alloying as it proved to be a cheap and easy way to produce (even metastable) nanostructured alloys. Especially Fe-Ni alloys have been studied intensely due to their technological and scientific importance. The MA process, however, is not fully understood. Furthermore, remanence properties of Fe80Ni20 are not well known. In our article "Monitoring the alloying process of mechanically synthesized Fe80Ni20through changes in magnetic properties (DOI: j.jallcom.2017.10.090, Volk et al., 2018) [1])" we investigated structural and magnetic properties of the intermediate and final alloys. Elemental Fe (99.5%) and Ni (99.7%) powders were filled in a 80 ml zirconia vials together with 3 mm zirconia milling balls and milled at 400 PRM with a planetary ball mill (Fritsch Pulverisette Premium 7). By subsampling the product at 14 different times during the process, the data presented here shows how crystalline structure (X-ray diffraction) and magnetic properties, induced as well as remanent, of the metastable Fe80Ni20 change during the mechanical synthesis.

10.
BMC Palliat Care ; 17(1): 58, 2018 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-29622004

RESUMO

BACKGROUND: Hospital costs and cost drivers in palliative care are poorly analysed. It remains unknown whether current German Diagnosis-Related Groups, mainly relying on main diagnosis or procedure, reproduce costs adequately. The aim of this study was therefore to analyse costs and reimbursement for inpatient palliative care and to identify relevant cost drivers. METHODS: Two-center, standardised micro-costing approach with patient-level cost calculations and analysis of the reimbursement situation for patients receiving palliative care at two German hospitals (7/2012-12/2013). Data were analysed for the total group receiving hospital care covering, but not exclusively, palliative care (group A) and the subgroup receiving palliative care only (group B). Patient and care characteristics predictive of inpatient costs of palliative care were derived by generalised linear models and investigated by classification and regression tree analysis. RESULTS: Between 7/2012 and 12/2013, 2151 patients received care in the two hospitals including, but not exclusively, on the PCUs (group A). In 2013, 784 patients received care on the two PCUs only (group B). Mean total costs per case were € 7392 (SD 7897) (group A) and € 5763 (SD 3664) (group B), mean total reimbursement per case € 5155 (SD 6347) (group A) and € 4278 (SD 2194) (group B). For group A/B on the ward, 58%/67% of the overall costs and 48%/53%, 65%/82% and 64%/72% of costs for nursing, physicians and infrastructure were reimbursed, respectively. Main diagnosis did not significantly influence costs. However, duration of palliative care and total length of stay were (related to the cost calculation method) identified as significant cost drivers. CONCLUSIONS: Related to the cost calculation method, total length of stay and duration of palliative care were identified as significant cost drivers. In contrast, main diagnosis did not reflect costs. In addition, results show that reimbursement within the German Diagnosis-Related Groups system does not reproduce the costs adequately, but causes a financing gap for inpatient palliative care.


Assuntos
Grupos Diagnósticos Relacionados/economia , Cuidados Paliativos/métodos , Idoso , Idoso de 80 Anos ou mais , Custos e Análise de Custo , Estudos Transversais , Grupos Diagnósticos Relacionados/tendências , Feminino , Alemanha , Custos de Cuidados de Saúde/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Cuidados Paliativos/economia , Cuidados Paliativos/tendências
13.
Ann Palliat Med ; 4(3): 156-61, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26231812

RESUMO

BACKGROUND: The concept of early palliative care (ePC) has received enormous recognition in the field of cancer care. Increasing evidence supports this approach, but outside the research arena, the implementation of sustainable clinical concepts rely on solutions for practical problems such as funding issues. Therefore, the article presented here discusses economic considerations associated with different concepts of ePC. MAIN POINTS: The specialist approach: the most frequently cited ePC trials assessing examine the concurrent provision of specialist palliative care in addition to routine care. Most of this specialist palliative care has been provided by multiprofessional teams in an outpatient setting of tertiary care centers. A number of the research groups have also provided data about the resource utilizations of this approach. From this, a rough estimate of the cost of early specialist palliative care can be derived. Yet, in many parts of North-America, Europe and other regions, funding modes for such outpatient specialist palliative care is non-existent. Recent studies have pointed out that ePC for inpatients is associated with cost-savings. These cost savings are even more pronounced the earlyer specialist palliative care is integrated in the care for the patients. Strengthening of general palliative care: most institutions recommend that palliative care as an approach should be strengthened as a part of standard care. To accomplish this, different measures such as teaching of general palliative care competencies of oncology teams, routine symptom assessment or the mandatory implementation of advanced care planning in care trajectories are being promoted. Due to the heterogeneity of these approaches, cost calculations are difficult, but can be weight against cost-saving estimated associated with for example less utilization of futile diagnostic and therapeutic procedures. CONCLUSIONS: Researchers, health care providers and policy makers need to distinguish the different concepts behind ePC before providing cost estimates. Detailed information is provided in this article. From our view, it is evident that neither of the two approaches (general vs. specialist) can be a one-or-the-other choice. Successful ePC will most likely rely on a joint effort of all medical disciplines and profession in close cooperation and early integration of specialist PC services. For such an approach, additional resources may be necessary, but from the public health perspective, cost-savings can also be assumed.


Assuntos
Assistência Ambulatorial/economia , Recursos em Saúde/economia , Neoplasias/economia , Cuidados Paliativos/economia , Análise Custo-Benefício , Humanos , Neoplasias/terapia , Manejo da Dor/economia
14.
MAbs ; 7(4): 732-42, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25996192

RESUMO

To monitor the Fc glycosylation of therapeutic immunoglobulin G in bioprocess development, product characterization and release analytics, reliable techniques for glycosylation analysis are needed. Several analytical methods are suitable for this application. We recently presented results comparing detection methods for glycan analysis that are separation-based, but did not include mass spectrometry (MS). In the study reported here, we comprehensively compared MS-based methods for Fc glycosylation profiling of an IgG biopharmaceutical. A therapeutic antibody reference material was analyzed 6-fold on 2 different days, and the methods investigated were compared with respect to precision, accuracy, throughput and analysis time. Emphasis was put on the detection and quantitation of sialic acid-containing glycans. Eleven MS methods were compared to hydrophilic interaction liquid chromatography of 2-aminobenzamide labeled glycans with fluorescence detection, which served as a reference method and was also used in the first part of the study. The methods compared include electrospray MS of the heavy chain and Fc part after limited digestion, liquid chromatography MS of a tryptic digest, porous graphitized carbon chromatography MS of released glycans, electrospray MS of glycopeptides, as well as matrix assisted laser desorption ionization MS of glycans and glycopeptides. Most methods showed excellent precision and accuracy. Some differences were observed with regard to the detection and quantitation of low abundant glycan species like the sialylated glycans and the amount of artefacts due to in-source decay.


Assuntos
Anticorpos Monoclonais/química , Fragmentos Fc das Imunoglobulinas/química , Imunoglobulina G/química , Ácidos Siálicos/análise , Animais , Células CHO , Cricetinae , Cricetulus , Glicosilação , Humanos , Proteínas Recombinantes/química
15.
Artigo em Inglês | MEDLINE | ID: mdl-25585386

RESUMO

Lead-based ABO3-type relaxors and related systems have numerous applications in modern technical devices because of their remarkably high dielectric permittivity and piezoelectric/electroelastic and electro-optic coefficients. However, lead is not desired from an environmental point of view, and to switch to alternative alkali-, Ba-, or Bi-based relaxor systems, one must understand in great detail the structural mesoscopic order and coupling processes responsible for the outstanding performance and multifunctionality of the exemplar Pb-based compounds. To elucidate the type of ferroic coupling, three relaxor compounds PbSc0.5Ta0.5O3 (PST), Pb0.78Ba0.22Sc0.5Ta0.5O3 (PST-Ba), and PbSc0.5Nb0.5O3 (PSN), were studied by polarized Raman scattering and acoustic emission at different temperatures and under an external electric field. The results reveal the coexistence of mesoscopic-scale ferroelectric and antiferroelectric coupling, which are predominantly related to B-site cations and A-site Pb cations, respectively. This suggests that the polar structural state of relaxors is frustrated ferrielectric. The presence of A-site cations with affinity to off-center is significant for the development of mesoscopic-scale antiferroelectric order coexisting with the mesoscopic-scale ferroelectric order.

16.
MAbs ; 7(1): 167-79, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25524468

RESUMO

Immunoglobulin G (IgG) crystallizable fragment (Fc) glycosylation is crucial for antibody effector functions, such as antibody-dependent cell-mediated cytotoxicity, and for their pharmacokinetic and pharmacodynamics behavior. To monitor the Fc-glycosylation in bioprocess development, as well as product characterization and release analytics, reliable techniques for glycosylation analysis are needed. A wide range of analytical methods has found its way into these applications. In this study, a comprehensive comparison was performed of separation-based methods for Fc-glycosylation profiling of an IgG biopharmaceutical. A therapeutic antibody reference material was analyzed 6-fold on 2 different days, and the methods were compared for precision, accuracy, throughput and other features; special emphasis was placed on the detection of sialic acid-containing glycans. Seven, non-mass spectrometric methods were compared; the methods utilized liquid chromatography-based separation of fluorescent-labeled glycans, capillary electrophoresis-based separation of fluorescent-labeled glycans, or high-performance anion exchange chromatography with pulsed amperometric detection. Hydrophilic interaction liquid chromatography-ultra high performance liquid chromatography of 2-aminobenzamide (2-AB)-labeled glycans was used as a reference method. All of the methods showed excellent precision and accuracy; some differences were observed, particularly with regard to the detection and quantitation of minor glycan species, such as sialylated glycans.


Assuntos
Anticorpos Monoclonais/química , Fragmentos Fc das Imunoglobulinas/química , Animais , Células CHO , Cromatografia Líquida de Alta Pressão , Cricetinae , Cricetulus , Glicosilação , Espectrometria de Massas
17.
Acta Biomater ; 9(12): 9492-502, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23896564

RESUMO

New developments in high-resolution, low accelaration voltage electron backscatter diffraction (EBSD) enable us to resolve and quantify the co-orientation of nanocrystals constituting biological carbonate crystals with a scan step resolution of 125 nm. This allows the investigation of internal structures in carbonate tablets and tower biocrystals in the nacre of mollusc shells, and it provides details on the calcite-aragonite polymorph interface in bivalves. Within the aragonite tablets of Mytilus edulis nacre we find a mesoscale crystallographic mosaic structure with a misorientation distribution of 2° full width at half maximum. Selective etching techniques with critical point drying reveal an organic matrix network inside the nacre tablets. The size scales of the visible aragonite tablet subunits and nanoparticles correspond to those of the open pore system in the organic matrix network. We further observe by EBSD that crystal co-orientation spans over tablet boundaries and forms composite crystal units of up to 20 stacked co-oriented tablets (tower crystals). Statistical evaluation of the misorientation data gives a probability distribution of grain boundary misorientations with two maxima: a dominant peak for very-small-angle grain boundaries and a small maximum near 64°, the latter corresponding to {110} twinning orientations. However, the related twin boundaries are typically the membrane-lined {001} flat faces of the tablets and not {110} twin walls within tablets. We attribute this specific pattern of misorientation distribution to growth by particle accretion and subsequent semicoherent homoepitaxial crystallization. The semicoherent crystallization percolates between the tablets through mineral bridges and across matrix membranes surrounding the tablets. In the "prismatic" calcite layer crystallographic co-orientation of the prisms reaches over more than 50 micrometers.


Assuntos
Carbonato de Cálcio/química , Mytilus edulis/química , Nácar/química , Animais , Plaquetas/metabolismo , Cristalização , Microscopia Eletrônica de Varredura , Mytilus edulis/ultraestrutura , Difração de Raios X
18.
Am J Hosp Palliat Care ; 30(4): 339-46, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22833555

RESUMO

OBJECTIVE: For adequate distress assessment in palliative care, we developed a screening evaluation tool. METHODS: Proven methods of scale construction led to a 53-item pilot form of the Advanced Cancer Patients' Distress Scale (ACPDS). We used Hornheide Questionnaire (HQ), Palliative Outcome Scale (POS), and Minimal Documentation System (MIDOS) for validation. Advanced cancer patients (N = 168) from 3 centers for palliative medicine (aged 23-89, 51% female) filled out the questionnaire. RESULTS: With a principal component analysis (PCA), we extracted 5 distress scales (emotional reactions/physical restrictions, communication deficits, negative social reactions, pain, and gastrointestinal symptoms). Internal consistencies varied between medium (.52) and very good (.88). Positive validity scores were found. CONCLUSIONS: Using the ACPDS may help to identify needs for palliative care interventions and enhance the quality of palliative care.


Assuntos
Atividades Cotidianas/psicologia , Neoplasias/psicologia , Cuidados Paliativos/psicologia , Psicometria/instrumentação , Perfil de Impacto da Doença , Doente Terminal/psicologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Dispneia/diagnóstico , Dispneia/etiologia , Dispneia/psicologia , Feminino , Gastroenteropatias/diagnóstico , Gastroenteropatias/etiologia , Gastroenteropatias/psicologia , Alemanha , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/complicações , Neoplasias/tratamento farmacológico , Dor/diagnóstico , Dor/etiologia , Dor/psicologia , Cuidados Paliativos/normas , Cuidados Paliativos/estatística & dados numéricos , Reprodutibilidade dos Testes , Distribuição por Sexo , Inquéritos e Questionários , Doente Terminal/estatística & dados numéricos , Adulto Jovem
19.
Artigo em Inglês | MEDLINE | ID: mdl-21937324

RESUMO

The exceptional properties of lead-based perovskite-type (ABO(3)) relaxor ferroelectrics are due to their structural inhomogeneities. At ambient conditions, the average structure is pseudocubic but rich in ferroic nanoregions too small to be directly studied by conventional diffraction analysis. However, combining in situ temperature and pressure diffraction and Raman scattering allows us to resolve the structural complexity of relaxors. Because of the different length and time scales of sensitivity, diffraction probes the long-range order, i.e., the structure averaged over time and space, whereas Raman spectroscopy can detect local structural deviations from the average structure via the anomalous Raman activity of the phonon modes that, when the symmetry of the average structure is considered, should not generate Raman peaks. Hence, the combined analysis of the long-range order induced at low temperatures or high pressures and of the phonon anomalies enhanced on temperature decrease or pressure increase can reveal the energetically preferred structural nanoclusters existing at ambient conditions. In this regard, high-pressure experiments are vital for understanding the nanoscale structure of relaxors. Using X-ray diffraction, neutron diffraction, and Raman scattering on stoichiometric and doped PbSc(0.5)Ta(0.5)O(3) and PbSc(0.5)Na(0.5)O(3), we demonstrate the existence of a pressure-induced cubic-to-rhombohedral continuous phase transition. The high-pressure structure has suppressed polar shifts of B-site cations, enhanced correlation of Pb-O ferroic species, and long-range ordered antiphase BO(6) octahedral tilts. The critical pressure is preceded by an intermediate pressure at which the coupling between off-centered Pb and B-cations is suppressed and octahedral tilting detectable by neutron diffraction is developed.

20.
Acta Crystallogr B ; 66(Pt 3): 280-91, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20484799

RESUMO

We have employed a combination of powder neutron diffraction and single-crystal synchrotron X-ray diffraction to characterize the pressure-induced phase transitions that occur in the perovskite-type relaxor ferroelectric PbSc(0.5)Ta(0.5)O(3) (PST) and Pb(0.78)Ba(0.22)Sc(0.5)Ta(0.5)O(3) (PST-Ba). At ambient pressure the symmetry of the average structure for both compounds is Fm3m as a result of partial ordering of the Sc and Ta cations on the octahedral sites. At pressures above the phase transition both the neutron and X-ray diffraction patterns exhibit an increase in the intensities of h,k,l = all odd reflections and no appearance of additional Bragg reflections. Synchrotron single-crystal X-ray diffraction data show that the intensity of hhh peaks, h = 2n + 1, does not change with pressure. This indicates that the structural distortion arising from the phase transition has a glide-plane pseudo-symmetry along the 111 cubic directions. Rietveld refinement to the neutron powder data shows that the high-pressure phase has either R3c or R3 symmetry, depending on whether the presence of 1:1 octahedral cation ordering is neglected or taken into account, and comprises octahedral tilts of the type a(-)a(-)a(-) that continuously evolve with pressure. The cubic-to-rhombohedral transition is also marked by a large increase in the anisotropy of the displacement ellipsoids of the Pb cations, indicating larger displacements of Pb cations along the rhombohedral threefold axis rather than within the perpendicular plane. For PST the anisotropy of the Pb displacement parameters decreases at approximately 3 GPa above the phase-transition pressure. For both PST and PST-Ba the average magnitudes of Pb-cation displacements expressed in terms of isotropic displacement ellipsoids gradually decrease over the entire pressure range from ambient to 7.35 GPa.

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