H.C. Starck (Germany)

When a two-component liquid resin is cured, it usuallyends upin the solid state and cannot be transferred to the liquid state again.This work introduces a polymeric material, which cross-links covalentlyat ambient temperatures, but can still be liquefied again on demand.The mechanism is based on the well-known concept of reversible cross-links,e.g., via Diels–Alder-reactions, which allow de-cross-linkingat elevated temperatures. The presented material, however, differsfrom known variants by the fact that the non-cross-linked state isliquid at ambient conditions. Thus, the cross-linked solid materialcan be reversibly transferred to the liquid state again by heating.In contrast to classical melting, the material remains in the liquidstate after cooling for a prolonged time. It therefore shows a behaviorthat is reminiscent of a melting hysteresis but is rather based ona superposition of thermodynamics and kinetics. At room temperature,cross-linking occurs rather slowly, while it is massively acceleratedat raised temperatures. In contrast to supercooled liquids with aphysical melting hysteresis, materials with a herein described “chemicalliquefication hysteresis” are attractive for multiple applications,e.g., recycling, adhesives, coatings, or even polymeric bulk materials.

Abstract The droplet size distribution in liquid–liquid dispersions is a complex convolution of impeller speed, impeller type, fluid properties, and flow conditions. In this work, we present threea priorimodeling approaches for predicting the droplet diameter distributions as a function of system operating conditions. In the first approach, called the two‐fluid approach, we use high‐resolution solutions to the Navier–Stokes equations to directly model the flow of each phase and the corresponding droplet breakup/coalescence events. In the second approach, based on an Eulerian–Lagrangian model, we describe the dispersed fluid as individual spheres undergoing ongoing breakup and coalescence events per user‐defined interaction kernels. In the third approach, called the Eulerian–Parcel model, we model a sub‐set of the droplets in the Eulerian–Lagrangian model to estimate the overall behavior of the entire droplet population. We discuss output from each model within the context of predictions from first principles turbulence theory and measured data.

Organic farming nowadays is becoming popular and getting high attention worldwide. This growing field needs many nutrient sources from natural resources since organic farming cannot use synthetic fertilizer. Thus, many sources of nutrient-rich solids are being used to fulfill the demand. Here, chicken feather powder, horn powder, poultry manure, and compost are used for producing organic fertilizer. These solid waste materials are blended in various compositions, i.e., horn plus poultry and horn plus compost. Selected fertilizer formulations were tested to grow barley in a pot trial inside a glasshouse using several dosages. After about four weeks old, the barley plant is harvested and weighed to determine the optimum fertilizer formula and dosage. It appears that fertilizer formula using horn and poultry is the best fertilizer that can produce the highest biomass in a respective time and compete with synthetic NPK fertilizer.

Dual topological materials are unique topological phases that host coexisting surface states of different topological nature on the same or on different material facets. Here, we show that Bi2TeI is a dual topological insulator. It exhibits band inversions at two time reversal symmetry points of the bulk band, which classify it as a weak topological insulator with metallic states on its 'side' surfaces. The mirror symmetry of the crystal structure concurrently classifies it as a topological crystalline insulator. We investigated Bi2TeI spectroscopically to show the existence of both two-dimensional Dirac surface states, which are susceptible to mirror symmetry breaking, and one-dimensional channels that reside along the step edges. Their mutual coexistence on the step edge, where both facets join, is facilitated by momentum and energy segregation. Our observation of a dual topological insulator should stimulate investigations of other dual topology classes with distinct surface manifestations coexisting at their boundaries.

Long term stability of ceramics at high temperatures is one of the great challenges of the contemporary technology developments. Multi‐component ceramics such as Si–B–C–N systems gain a lot of interest for high temperature applications due to the stability of their amorphous inorganic network arising from strong covalent bonding. The polymer derived ceramics (PDC) route enables the synthesis of such materials from preceramic polymers as well as their manufacturing as specific ceramic geometries, which are difficult to obtain otherwise. This review proposes an overview of the works related to the development of Si–B–C–N ceramics through the PDC route in the last 30 years. A particular focus is made on the relation between the chemical structure of the precursors and the properties of the resulting ceramics. The main topics reviewed are related to the synthesis of tailor‐made polymeric precursors, to their processing to ceramic components, and to the characterization of the material properties and functionalities. The various strategies adopted for the development of shaped Si–B–C–N ceramics as functional materials are presented and the trend of nowadays research for future evolution of Si–B–C–N materials is discussed.

The application of Ti-6Al-4V alloy or commercially pure titanium for additive manufacturing enables the fabrication of complex structural implants and patient-specific implant geometries. However, the difference in Young’s modulus of α + β-phase Ti alloys compared to the human bone promotes stress-shielding effects in the implant–bone interphase. The aim of the present study is the mechanical characterization of a new pre-alloyed β-phase Ti-42Nb alloy for application in additive manufacturing. The present investigation focuses on the mechanical properties of SLM-printed Ti-42Nb alloy in tensile and compression tests. In addition, the raw Ti-42Nb powder, the microstructure of the specimens prior to and after compression tests, as well as the fracture occurring in tensile tests are characterized by means of the SEM/EDX analysis. The Ti-42Nb raw powder exhibits a dendrite-like Ti-structure, which is melted layer-by-layer into a microstructure with a very homogeneous distribution of Nb and Ti during the SLM process. Tensile tests display Young’s modulus of 60.51 ± 3.92 GPa and an ultimate tensile strength of 683.17 ± 16.67 MPa, whereas, under a compressive load, a compressive strength of 1330.74 ± 53.45 MPa is observed. The combination of high mechanical strength and low elastic modulus makes Ti-42Nb an interesting material for orthopedic and dental implants. The spherical shape of the pre-alloyed material additionally allows for application in metal 3D printing, enabling the fabrication of patient-specific structural implants.

The article contains sections titled:1.Survey1.1.Saltlike Carbides1.2.Metal‐like Carbides1.3.Diamond‐like Carbides1.4.Carbides of Nonmetallic Elements1.5.Crystal Structure1.6.General Production Processes1.7.Uses2.Metal‐like Carbides of Industrial Importance2.1.Tungsten Carbide2.2.Titanium Carbide2.3.Tantalum Carbide2.4.Niobium Carbide2.5.Zirconium Carbide2.6.Hafnium Carbide2.7.Vanadium Carbide2.8.Chromium Carbide2.9.Molybdenum Carbide3.Mixed Carbides3.1.Tungsten‐Titanium Carbide3.2.Other Mixed Carbides3.3.Carbonitrides3.4.Mixed Carbonitrides4.Carbides of the Iron Group and Manganese5.Complex Carbides

We present results of texture characterization and predictions of a multiscale physically based constitutive law developed to predict the mechanical response and texture evolution of body-centered cubic metals. The model is unique in the sense that single crystal deformation results not only from the resolved shear stress along the direction of slip (Schmid law) but also from shear stresses resolved along directions orthogonal to the slip direction as well as the three normal stress components (non-Schmid effects). The single crystal model is implemented into a visco-plastic self-consistent homogenization scheme containing a hardening law for crystallographic slip. The polycrystal model is calibrated using a set of mechanical test data collected on a tantalum-tungsten alloy, Ta-10W, in tension and compression and pure tantalum, Ta, in tension, compression, and cross-rolling. We demonstrate that the model effectively captures the texture evolution in all cases. We show that alloying has the effect of increasing the dislocation friction stress, the trapping rate of dislocations, and activation barrier for recovery.

Posttransplant lymphoproliferative disorder (PTLD) is a well-established complication of immunosuppression. The involvement of the gastrointestinal (GI) tract occurs in 25% of all cases of PTLD. Fortunately, surgical intervention is seldom required. We report our experience of surgical treatment of complicated GI-PTLD after liver transplantation (LTx). A retrospective analysis of 5677 adult patients who underwent LTx between 1983 and 2009 was conducted. Thirty-six patients presented with GI-PTLD. Sixteen patients presented with complications associated with GI-PTLD requiring emergency surgery. The average (SD) time from LTx to GI surgery was 7.9 (5.8) years (range, 4 months to 17 years). Indications for surgical intervention were small bowel obstruction (seven cases), perforation (six cases), and GI bleeding (three cases). Most GI-PTLD occurred in the small bowel or right colon (81%). In addition to the surgery, treatment of PTLD consisted of reduction of immunosuppression, use of rituximab (n=10), and systemic chemotherapy (n=7). Overall mortality was 69%, with most of the deaths occurring within 8 months after emergency laparotomy. GI bleeding and perforation were associated with higher mortality (>66%). Despite higher early mortality in the surgical group, no differences on long-term outcome were observed between patients with GI-PTLD who required surgery and those who did not (P=0.371). In summary, GI-PTLD requiring surgical intervention is an extremely rare condition with high early mortality. Most of the cases are monoclonal, present a late onset, and involve the lower GI tract. Intestinal obstruction is the main indication for surgical intervention and is associated with better prognosis.