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In times of crisis, rapid deployment of clinical resources to under-served areas/populations is needed, particularly in the absence of an established health care infrastructure. The COVID-19 pandemic exposed profound gaps in care for people experiencing homelessness.1-3 A Mobile COVID-19 Unit was

IntroductionDiabetes is one of the most common serious chronic health conditions in the USA. People living with diabetes face multiple barriers to optimal diabetes care, including gaps in access to medical care and self-management education, diabetes distress, and high burden of treatment. Community paramedics (CPs) are uniquely positioned to support multidisciplinary care for patients with diabetes by delivering focused diabetes self-management education and support and bridging the gaps between patients and the clinical and community resources they need to live well with their disease.Methods and analysisWe will conduct a pragmatic single-arm prospective trial of a CP-led Diabetes Rescue, Engagement and Management (D-REM) programme that seeks to reduce diabetes distress. We will enrol 70 adults (≥18 years) with diabetes who have haemoglobin A1c (HbA1c)≥9.0%, experienced an emergency department (ED) visit or hospitalisation for any cause within the prior 6 months, and reside in areas with available CP support in Southeast Minnesota (Olmsted, Freeborn and Mower counties) and Northwest Wisconsin (Barron, Rusk and Dunn counties). Participants will be identified using Mayo Clinic electronic health records, contacted for consent and enrolled into the D-REM programme. Visit frequency will be individualised for each patient, but will be an average of four CP visits over the course of approximately 1 month. Outcomes will be change in diabetes distress (primary outcome), confidence in diabetes self-management, health-related quality of life, self-reported hypoglycaemia and hyperglycaemia, HbA1c, ED visits and hospitalisations. Outcomes will be assessed on enrolment, programme completion and 3 months after programme completion.Ethics and disseminationThe study was approved by Mayo Clinic Institutional Review Board. Findings will be disseminated through peer-reviewed publications and presentations. If demonstrated to be successful, this model of care can be implemented across diverse settings and populations to support patients living with diabetes.Trial registration numberNCT04385758.

The stress distribution ahead of the crack tip along the crack-line for the center cracked specimen, loaded by two pairs of symmetric concentrated forces on the crack is evaluated by means of finite element method

The deformation behavior of pure recrystallized molybdenum under cyclic and static loads was investigated in the temperature range between 30 degrees C and 100 degrees C, for stress amplitudes between 100 MPa and 250 MPa and for static loads up to 200 MPa. The results show that in spite of the low test temperatures and stress levels the Mo material exhibits considerable plastic strains which depend sensitively on frequency/time and small changes in temperature. The activation energy deduced for the static and dynamic deformation is less than 0.98 eV which indicates thermally activated processes, to be explained by a dislocation kink model as described in the literature. The low-temperature fatigue behavior appears strongly influenced by creep-fatigue interaction phenomena.

The deformation behavior of a recrystallized high purity Mo at constant stresses and at moderately elevated temperatures up to 90 C was studied. A creep-like viscoplasticity was observed at the tested stress levels for below the yield stress. Upon loading to a constant stress level the specimen indicated a rapid initial increase in strain. then the material deforms to an exponential law and tends to saturate as time goes infinite. It was found that the testing temperature has a strong effect on the initial strain rate, while little effect on the saturation strain was found. The saturation strain increases with increasing stress. A mechanical model was proposed employing an elastic element, a viscous element and a rigid-plastic element. This model accounts well for the experimentally observed deformation behavior in Mo. Micromechanically, the kink-pair model was cited for the interpretation. Possibly some other mechanisms could also operate at the same time, including the grain boundary sliding in this fine grain sized microstructure.

From low-deformation fracture surfaces obtained by impact loading at 77K or by high cycle fatigue testing, the load bearing cross section can be quantitatively determined both for sintered iron and high strength steel, respectively. In the sintered iron, the fracture mode - cleavage fracture vs. ductile rupture ― also gives indication of the pore connectivity. In the technically interesting porosity range 5 to 20 % sintered iron can be imagined as containing both interconnected and isolated pores which are respectively grouped in clusters. Slight changes in total porosity or the sintering regime change the ratio of isolated to interconnected pores and thus strongly affect the load bearing cross section which in turn influences in particular the mechanical properties of the material

A laser interferometric system is presented which is based on the optical principle of a modified Young's two-slit phenomenon. The system consists of a coherent monochromatic light source which is incident on two microhardness indentations. The two diffracted wave fronts form interference fringes which are detected by a CCD camera and stored in a digital frame grabber for further processing. This interferometric sensor was used to determine localized displacements of the markers of better than two nm. The system was adapted to a commercial tensile testing machine to measure local elastic displacements from which elastic constants were deduced. Crack opening displacements (COD) were measured along fatigue cracks and in areas within 10 μm off the crack tip. The laser optical sensor was also adapted to a heating system to determine local thermal strains from small specimens from which the coefficient of linear thermal expansion in the temperature range between 20 - 400° may be determined. Results obtained for various materials (metals, polymers, ceramics) will be presented.

Ni–base superalloys which are used in thermodynamically metastable conditions develop an undesired decrease in mechanical strength during serivce. In situ fracture experiments of aged (10 00 h/788 °C) and fully heat treated specimens of IN 738 subsequently examined with AES and SEM revealed pronounced segregation of P and S to phase boundaries. In spite of the low levels of these elements in such alloys (?0.003 wt. % in the case of S), a considerable enrichment of S and P was found in their interfacial layers. A weakening effect is expected due to interface segregation of these elements. SEM results show that the fracture morphology is different for thermally aged and fully heat treated specimens. These SEM results confirm the weakening effect of phase boundaries by segregation.

Dimensional changes in austenitic stainless steels exposed to fast neutron fluxes have been attributed mainly to void formation and thermal and irradiation induced creep. In this in-vestigation, immersion bulk density measurements were performed on variously preheated AISI Types 304, 316L and 316 stainless steels. The results show that the density changes accompanying sequential precipitation of the various carbide (M23C8, M6C) and intermetallic phases (sigma, chi, eta) during thermal aging can be comparable to those attributed to void formation at low fast neutron fluences. Vacuum melted Type 316 stainless steel always den-sified with aging at 725°C or 810°C and exhibited higher rates of precipitation and recovery of cold work during aging than the equivalent air melted steel. The direction of the density change in the air melted material was dependent upon the prior thermomechanical treat-ments. This behavior can be rationalized on the basis of a higher impurity content in the air melted material. A mathematical model was constructed which successfully explains the variation of bulk density due to sequential precipitation in Type 18-12 austenitic stain-less steels.

Experiments of vacuum brazing under both microgravity and 1-g conditions show the effect of hydrostatic pressure on ga-filling. The absence of buoyancy forces under microgravity affects the microstructure of the solidified braze in the joint.

The size of the dislocation cells produced by deformation at the fatigue crack tip in copper specimens was used as a measure of the crack tip stress amplitude. Using the cyclic stress-strain curve, the values of the crack tip plastic strain amplitude and their dependence on the macroscopic stress intensity factor were obtained. While the fatigue crack propagation rate expressed as a function of the stress intensity factor is strongly influenced by the testing temperature and frequency, it is almost independent of these parameters when expressed in terms of the crack tip plastic strain amplitude. The results of a finite element computation led to the same conclusion.

The effects of aging treatments on the microstructure of the Ni-base superalloys IN-738 HC and IN-738 LC were investigated. Changes in (i) size, morphology, and distribution of the γ′-phase, (ii) the amount of M23C6-carbide, and (iii) the occurrence of additional phases and phase instabilities were quantitatively determined. The results indicate the possibility to deduce an unknown thermal history from the observed microstructure. Einflus von Alterungswarmebehandlungen auf das Gefuge der Ni-Basis Superlegierung IN-738 Proben der Ni-Basis Superlegierungen IN-738 LC und IN-738 HC wurden untersucht, um den Effekt vorhergegangener thermischer Alterung auf das Gefuge dieser Proben zu finden. Zwischen den Alterungsbedingungen und dem Gefuge konnten folgende Zusammenhange aufgezeigt werden: (i) Grose, Morphologie und Verteilung der γ′-Phase, (ii) Vorliegen und Menge von M23C6-Phase und (iii) Auftreten zusatzlicher Phasen oder Phasenumwandlungen. Aufgrund des oben erwahnten Zusammenhanges zwischen Alterungsbedingungen und Gefuge ist es moglich, aus dem Gefuge unbekannter Proben deren thermische Vorgeschichte zu ermitteln.

After a silicon slice with a mechanically damaged surface was annealed at 1200°C for 2 hours in wet oxygen, two-dimensional defects were present extending from the surface into the slice. The defects are shown to be thin plates of amorphous material, probably oxide, and it is suggested that they arise by a mechanism analogous to that described by Silcock and Tunstall (1964) for the precipitation of NbC in steel.

An electron-microscope study of the corrosion fracture surfaces of sensitized austenitic stainless steel specimens exposed to Strauss (CuSO4-H2SO4) solutions and Huey solution (HNO3), respectively, revealed marked differences in the corrosion attack. In the Strauss test the dissolution of the matrix occurs along a narrow region in the vicinity of the carbide particles which remain essentially unattacked, while in the Huey test both the carbide particles as well as a wider region of the matrix are attacked. The extent of the preferentially dissolved region around the carbide particles after the Strauss test suggests that the metal dissolution cannot be explained on the basis of a local chromium impoverishment, but that an electrochemical process between a more noble carbide and the less noble matrix is operative. This is supported by results of electrochemical potential measurements on carbide and steel samples in the various corrosive environments which show that in the Strauss solution the carbide has a more noble electrochemical potential than the steel matrix, while in the Huey solution the carbide is less noble than the steel matrix.

A survey evaluation of the quality of commercial silicon used in the preparation of p-n junction devices has been made, with emphasis on the detection and characterization of micro-inhomogeneities. The examination techniques included transmission electron microscopy, special etching techniques with optical microscopy, and microresistivity determination. These investigations have shown that almost all silicon produced by current commercial techniques has an appreciable concentration of microdefects, including precipitates and microcrystallographic defects, which are too small to be detected by conventional techniques. Furthermore the impurity distribution is inhomogeneous on a microscopic scale. These microinhomogeneities are frequently present in sufficient concentration to be more influential in determining the quality of the finished device than the material properties usually specified. Some suggestions are made concerning the establishment of standards of acceptability for the major types of microdefects and for developing simple, rapid evaluation procedures.

The creep behaviour of fine wires of pure powder metallurgical tungsten was studied over the temperature range 2100–3100°C. It was found that the steady-state creep rate is given by This result differs substantially from other reported work performed on specimens of larger diameter of polycrystalline pure tungsten. The difference is due to the fact that in the fine wire specimens numerous grain boundaries traverse the entire diameter. Creep can therefore take place by grain boundary sliding in these samples without the necessity of extensive grain deformation as is required for larger specimens where the grain size is much smaller than the sample diameter.

Transmission electron microscope examinations of silicon single crystals, phosphorus‐diffused at low temperatures from anodic oxide films as phosphorus sources, showed the presence of crystallographically oriented precipitate. X‐ray and electron diffraction investigations of SiP and SiAs single crystals prepared by a vapor‐growth method revealed the orthorhombic crystal structure of the as‐grown compounds. Using these structure data, the precipitate in the diffused silicon could be identified by electron diffraction as SiP. The orientation relationship SiP‐precipitate/Si‐matrix was determined.

Irregular n -type emitter protrusions in diffused-alloyed thyristor devices cause inferior forward-biased blocking characteristics. It is assumed that the forward switching voltage is mainly a function of the smallest p -type base width resulting from a localized irregularity of the n + -type emitter. To demonstrate the validity of the assumption the switching voltage was calculated as a function of the p -type base width. Computed data were then compared with experimental data. Good agreement was obtained for both devices with shallow and devices with deep emitter protrusions.

Epitaxial Si layers grown on (111) Si substrates by vapor decomposition methods often exhibit a triangle and/or line type of surface defect. An investigation of such defects by optical microscopy and particularly transmission electron microscopy has shown the defects to be stacking faults. The stacking faults usually commence at certain points lying in or close to the substrate/layer interface, and develop in a regular manner along one or more of the three inclined {111} planes. As growth proceeds the stacking faults rapidly increase in area, spread laterally and eventually interact with one another. A simple growth mechanism is proposed based on the assumption that nucleation centers occasionally go down in incorrect sequence, i.e., small areas of stacking fault form on the (111) plane parallel to the substrate/layer interface. Many of the experimental observations can be explained using this model.

Single crystal Si specimens have been unidirectionally abraded, the abrasives ranging from 0•25 micron diamond to No. 240 SiC paper, and examined by transmission electron microscopy and standard metallographic methods. The investigation showed that the damage varied in a progressive manner with the severity of the abrasion treatment, ranging from rows of single dislocations to bands of both dislocation networks and cracked material. The corresponding depths of damage ranged from approximately 0•2 to 24 microns. Anisotropy of damage occurred for the fine abrasions (often termed polishing), but was not observed for the coarse abrasions. When abraded specimens were annealed, the dislocations changed their configuration, and new dislocations propagated in order to relieve elastic strains. A qualitative description of the abrasion process for Si based on the results of the investigation is given.

In Au-diffundierten, Phosphor-dotierten Si-Scheiben wurden durch Transmissionselektronenmikroskopie feine Ausscheidungsteilchen beobachtet, von denen angenommen wurde, das sie aus einer Au−P-Verbindung bestehen. Um die fur eine Identifizierung dieser Ausscheidung mittels Elektronenbeugung notwendigen Daten der Kristallstruktur zu eihalten, wurde eine geringe Menge von Au2P3-Einkristallen durch eine Gasphasentransportreaktion der Elemente hergestellt. Die erhaltenen Kristalle wurden chemisch und durch Rontgenbeugung untersucht. Weiters wurden Aussagen uber die Morphologie und die Stabilitat der Au2P3-Kristalle erhalten.

Although Type 316 austenitic stainless steel is widely used in steam generating plants and nuclear reactors the knowledge about aging reactions, nature of precipitates, and precipitation kinetics during high temperature exposure is limited. Time-temperature-precipitation (TTP) diagrams were determined between 400° and 900°C for up to 3000 hr as a function of carbon content, solution treatment temperature, and cold work. The nucleation and growth phenomena, morphology, and composition of the various carbide (M23C6, M6C) and intermetallic phases (σ, χ, η were determined. The complex sequence of phase instabilities can be explained on the basis of the carbon content, effect of molybdenum and chromium on the carbon solubility, thermodynamic stability of the phases, and the kinetics of the various precipitation reactions.

The dislocation arrangements in 304 stainless steel and Incoloy 800 have been determined as a function of temperature and strain. Dislocation pile-ups were observed in both alloys in spite of the fact that the stacking fault energies were considerably different, viz. 30 erg/cm2 for the Incoloy 800. The stress-corrosion behaviour of the two alloys in magnesium chloride boiling at 142°C was determined. The Incoloy 800 was found to be considerably more resistant than the 304 stainless steel. After critically reviewing the current theories of stress corrosion and structural and stress-corrosion data for a series of austenitic alloys, it was concluded that the data could best be correlated with the theory proposed by Swann. According to this theory, the presence of short range order is expected to markedly influence dislocation arrangement and stress-corrosion behaviour. A review of the literature revealed that there is some indirect evidence to indicate the presence of short range order in certain of the austenitic alloys, but the evidence is not conclusive.

The mechanism of stress-corrosion cracking was investigated in purified 16%Cr-20%Ni stainless steels, with and without single-element additions of manganese, molybdenum and titanium. Potential/time behaviour and potentiostatic current/time curves were studied in 42% MgCl2 at 146°C. The purified alloy did not crack under severe testing conditions, manganese addition left it apparently immune, but molybdenum or titanium additions induced cracking. The effect of deformation on dislocation mobility was examined by transmission electron microscopy. All of the results are in accord with a periodic electrochemical-mechanical mechanism of crack propagation, wherein susceptibility to cracking is associated with highly restricted slip, alloys which readily cross slip being immune. It is shown that cracking is associated also with low stacking fault energy.

A method is described for the preparation of wire samples for transmission electron microscopy. The specimen preparation involves three consecutive steps, i.e. pregrinding, electrolytic microjet machining and final bath polishing. By this method electron transparent areas of wires less than 1 mm in diameter can be prepared in less than one hour. Further advantages of this method are that the area of examination can be located very accurately, specimen deformation due to handling is avoided, and very brittle materials can be prepared conveniently.

A jet chemical polishing method suitable for preparing Si and Ge specimens for examination by transmission electron microscopy is described. For Si a HNO3/HF solution is used, while for Ge either a HNO3/HF or a NaClO solution is used. The method is simple and rapid. Electron micrographs illustrating the method are given.

This paper presents a review of the information available on the properties and performance of the strong highly corrosion resistant alloy IN939 which is being used increasingly for vanes and blades in land-based gas turbines. Particular emphasis has been placed on the large amount of new data now available from the European Collaborative Project COST50 and it will be seen that the behaviour of the alloy has been well characterised although there is insufficient information on the low cycle fatigue performance. It is shown that the alloy compares favourably with IN738LC and in service has superior corrosion resistance.

The relationship between powder metallurgical processing parameters, the resulting sintered density, the shape and dimensions of sintering pores, and their effect on the static as well as dynamic mechanical properties of compacts made of high-purity iron powder was investigated. The fatigue strength was found to be related to the maximum size of pores or clusters of pores, with the dynamic Young's modulus appearing as a practical parameter to relate porosity with fatigue strength.

The progress of the divertor target plate design studies for the Next European Torus (NET) within the NET Team is summarized. The main design specifications e.g. the high peak power load and the assumptions on erosion and disruptions are elucidated. Emphasis is put on concepts for the NET Physics Phase i.e. with carbon based armour materials.

Seit den Untersuchungen von Cochardtl an Co-Basis-Legierungen ist bekannt, das geringe Zusatze von Hf die Kriech- und Kerbschlageigenschaften dieser Legierungen gunstig beeinflussen. Auch in Ni-Basis-Superlegierungen konnte durch Zugabe geringer Mengen von Hf (bis ca. 2%) eine Verbesserung mechanischer Eigenschaften bewirkt werden.

Cellular and molecular repair was studied at 23 degrees C using split-dose recovery and alkaline elution techniques, respectively, as a function of cellular oxygen and nutrient conditions. Hypoxic cells (0.001% O2) in full medium showed a partial reduction in the level of sublethal damage (SLD) repair relative to aerated cells (21% O2, OER equal to 3.2 relative to 0.001% O2); the respective repair kinetics were similar with a common repair half-time of 30 min. Similarly, hypoxic cells showed a slight reduction in strand break rejoining capacity compared to aerated cells. Under nutrient deprivation, anoxic cells displayed no SLD repair or strand break repair, while aerated cells exhibited the same level of SLD and strand break repair as for well-fed cells. In addition, nutrient deprived cells at low O2 levels (0.03%, OER equal to 1.15) displayed normal SLD and strand break repair capability. These results indicate that both nutrient and O2 deprivation are necessary for complete inhibition of cellular and molecular repair, and low levels of O2 (0.03%) can effectively reverse this inhibition.

Transmission electron microscope studies have shown that commercial silicon materials have varying concentrations of microdefects which are not detectable by normal evaluation procedures. The size of these defects ranges from less than 100A up to microns. The following types of defects have been found: small loop-shaped defects, large loop-shaped defects, inclusions of several kinds, and precipitates including those associated with crystallographic defects. The chemical composition of these particles, precipitates, and inclusions are generally uncertain; but some evidence exists that SiC, SiO2, and possibly Si3N4 are present. The widespread occurrence of microdefects in standard or premium quality silicon emphasizes the need for developing improved materials growth techniques and rapid procedures for detecting microdefects. The frequency of occurrence of the different varieties of microdefects differs with the type of material; however, crystals grown by the three principal techniques - float-zone, Czochralski, and crucibleless pulling - did not differ significantly in the degree of the overall microdefect problem. The effects of microdefects on devices depends strongly on the nature and size of the defect, whether it is conducting (metallic), non-conducting, or purely crystallographic. The size of the defect is important in determining the behavior of the device under electrical stress and during long time operation. Indirect effects, in particular precipitation of fast-diffusing heavy metal impurities on microdefects, are believed to be a significant cause of poor device performance. Qualitative relationships between microdefects and the quality of p-n junction devices have been established.

The damage which accumulates during cyclic deformation of metals and alloys is characterized by internal dislocation reactions and by the formation of “persistant slip bands” in surface near regions. The latter are thought to contribute to the nucleation of microcracks which propagate and finally lead to fatigue failure.The determination of the microstructural and topographical changes occuring progressively during fatigue exposure is of considerable scientific and technical interest. A detailed investigation of the kinetics of these changes requires in-situ examination which are best carried out with a SEM due to the large depth of focus, the wide magnification range, and the possibilities of electronic signal processing and video recording.

A carbon film vapour deposited on to Si surfaces can be detached by dissolving the `natural' surface oxide film. This oxide film is extremely thin, so that its dissolution practically has no deleterious effect on the surface features of the Si sample. Since the oxide film rapidly forms again after exposure of the sample to air, the replicating process can be repeated several times without a detectable deterioriation of the sample surface.