Integrating dynamic spectrum access and device‐to‐device via cloud radio access networks and cognitive radio

Dynamic Spectrum Access (DSA) can be integrated with Device‐to‐Device (D2D) communications to enable the exploitation of unused spectrum portions and to address the spectrum scarcity problem. Spectrum management mechanisms integrated into DSA and D2D allow low‐power communications between User Equipments without interfering with licensed primary users. However, these mechanisms tend to be energy and processing intensive, being unfeasible to implement in User Equipments with strict battery and processing limitations. On the other hand, Cloud Radio Access Networks already leverage the virtually unlimited computing capacity of clouds for baseband processing functions. Thus, in this article, we propose the Cognitive Radio Device‐to‐Device (CRD2D) approach aiming to offload spectrum management functionality to the cloud taking advantage of Cloud Radio Access Networks architecture to support the integration of DSA and D2D.     

Programming Delayed Dissolution Into Sacrificial Bioinks For Dynamic Temporal Control of Architecture within 3D-Bioprinted Constructs

Sacrificial printing allows introduction of architectural cues within engineered tissue constructs. This strategy adopts the use of a 3D-printed sacrificial ink that is embedded within a bulk hydrogel which is subsequently dissolved to leave open-channels. However, current conventional sacrificial inks do not recapitulate the dynamic nature of tissue development, such as the temporal presentation of architectural cues matching cellular requirements during different stages of maturation. To address this limitation, a new class of sacrificial inks is developed that exhibits tailorable and programmable delayed dissolution profiles (1–17 days), by exploiting the unique ability of the ruthenium complex and sodium persulfate initiating system to crosslink native tyrosine groups present in non-chemically modified gelatin. These novel sacrificial inks are also shown to be compatible with a range of biofabrication technologies, including extrusion-based printing, digital-light processing, and volumetric bioprinting. Further embedding these sacrificial templates within cell-laden bulk hydrogels displays precise control over the spatial and temporal introduction of architectural features into cell-laden hydrogel constructs. This approach demonstrates the unique capacity of delaying dissolution of sacrificial inks to modulate cell behavior, improving the deposition of mineralized matrix and capillary-like network formation in osteogenic and vasculogenic culture, respectively.     

Implied Open-circuit Voltage Imaging via a Single Bandpass Filter Method—Its First Application in Perovskite Solar Cells

A novel, camera-based method for direct implied open-circuit voltage (iV_OC) imaging via the use of a single bandpass filter (s-BPF) is developed for large-area photovoltaic solar cells and precursors. The photoluminescence (PL) emission is imaged using a narrow BPF with centre energy inside the high-energy tail of the PL emission, utilising the close-to-unity and nearly constant absorptivity of typical photovoltaic devices in this energy range. As a result, the exact value of the sample's absorptivity within the BPF transmission band is not required. The use of an s-BPF enables a fully contactless approach to calibrate the absolute PL photon flux for spectrally integrated detectors, including cameras. The method eliminates the need for knowledge of the imaging system spectral response. Through an appropriate choice of the BPF centre energy, a range of absorber compositions or a single absorber with different surface morphologies, such as planar and textured, can be imaged, all without the need for additional detection optics. The feasibility of this s-BPF method is first validated. The relative error in iV_OC is determined to be ≤1.5%. The method is then demonstrated on device stacks with two different perovskite compositions commonly used in single-junction and monolithic tandem solar cells.     

The use of the aquatic moss Fontinalis antipyretica L. ex Hedw. as a bioindicator for heavy metals: 3. Cd2+ accumulation capacities and biochemical stress response of two Fontinalis species

We studied heavy metal stress responses of two Fontinalis species, F. antipyretica and F. dalecarlica, collected from two habitats in Germany and Canada. The capacities of the two species for extracellular adsorption (biosorption) and intracellular uptake (bioaccumulation) of Cadmium (Cd2+) were investigated in the laboratory. Time-dependent Cd2+ adsorption by cell wall and intracellular uptake differed significantly between the two species. These differences were related to the number of Cd2+ binding sites, resulting from differences in leaflet surface and cell wall composition. Glutathione (GSH) levels in response to Cd2+ exposure were monitored over a 10-day period. GSH synthesis differed significantly between the two species. Both Fontinalis species appear to be suitable for heavy metal biomonitoring in aquatic habitats.     

Structure quality in deep X-ray lithography applying commercial polyimide-based masks

The structure quality of deep X-ray lithography components strongly depends on the quality of the applied X-ray mask. In this article we compare the results obtained with two different mask types. Sophisticated working masks generated by e-beam lithography, soft X-ray lithography and electroplating of gold absorbers on a titanium mask membrane have been fabricated at the Institute for Microstructure Technology, Research Center, Karlsruhe (FZK/IMT), Germany. Prototype masks generated by e-beam lithography, optical lithography and electroplating of gold absorbers on a polyimide mask membrane have been fabricated by Optnics Precision, Japan, with the aim to offer commercially available low cost masks. Both mask types were applied to pattern PMMA resist layers of 300–750 μm thickness at the 2.5 GeV electron storage ring ANKA, Germany, using comparable process parameters. FZK/IMT masks provide microstructures with significantly better structure quality. The layout area, however, is currently limited to 12 cm², and the Ti mask membrane tends to lead to a slight resist surface attack, such as rounding of the resist edges. Optnics masks provide microstructures with reduced structure quality due to sidewall striations (sidewall roughness up to 2 μm) and thermal distortions (of up to 3–5 μm) which limit the potential scope of applications. They could nevertheless potentially be applied as low quality, low cost X-ray masks. High resolution and high accuracy applications, however, require more sophisticated but also more expensive masks, like the Ti-masks from FZK/IMT.     

UML vs. classical vs. rhapsody statecharts: not all models are created equal

State machines, represented by statecharts or state machine diagrams, are an important formalism for behavioural modelling. According to the research literature, the most popular statechart formalisms appear to be Classical, UML, and that implemented by Rhapsody. These three formalisms seem to be very similar; however, there are several key syntactic and semantic differences. These differences are enough that a model written in one formalism could be ill-formed in another formalism. Worse, a model from one formalism might actually be well-formed in another, but be interpreted differently due to the semantic differences. This paper summarizes the results of an informal comparative study of these three formalisms with the help of several illustrative examples. We present a classification of the differences according to the nature of potential problems caused by each difference. In addition, for each difference we discuss how translation between formalisms can be achieved, if at all.     

From Shape to Function: The Next Step in Bioprinting

In 2013, the “biofabrication window” was introduced to reflect the processing challenge for the fields of biofabrication and bioprinting. At that time, the lack of printable materials that could serve as cell-laden bioinks, as well as the limitations of printing and assembly methods, presented a major constraint. However, recent developments have now resulted in the availability of a plethora of bioinks, new printing approaches, and the technological advancement of established techniques. Nevertheless, it remains largely unknown which materials and technical parameters are essential for the fabrication of intrinsically hierarchical cell–material constructs that truly mimic biologically functional tissue. In order to achieve this, it is urged that the field now shift its focus from materials and technologies toward the biological development of the resulting constructs. Therefore, herein, the recent material and technological advances since the introduction of the biofabrication window are briefly summarized, i.e., approaches how to generate shape, to then focus the discussion on how to acquire the biological function within this context. In particular, a vision of how biological function can evolve from the possibility to determine shape is outlined.     

Single and Double Polymer Layer Arrangements of Acid Groups Containing Cellulose and Basic Groups Containing Polyethyleneimine on Steel

This paper presents the first results of a project aimed at investigating the arrangement of polyelectrolyte layers on unalloyed steel. We studied the structure of double and single polymer layers consisting of cellulose phosphate (HP‐PP‐C) and polyethyleneimine (PEI). Layers were characterized by variable angle ellipsometry, AFM and XPS. In particular, XPS indicated the incorporation of iron ions into cellulose phosphate layers, but, in contrast, these ions could not be observed in PEI layers. Results indicated that the homogeneity and qualitative corrosion performance of double layers (HP‐PP‐C/PEI) on unalloyed steel depend on the deposition of cellulose phosphate at the interface with steel.

     

Herstellung von hydrolysestabilen Ammoniumsalzen sulfonierter Phosphite und deren Einsatz als Cokatalysatoren in der rhodiumkatalysierten Hydroformylierung

Hydrolytic Stable Ammonium Salts of Sulfonated Organic Phosphites and their Use as Cocatalysts in the Rhodium-catalyzed Hydroformylation of Olefins Ammonium salts of sulfonated organic phosphites, which are resistant to hydrolysis, have been prepared by transesterification of triphenylphosphite with mono-ammonium salt of p-hydroxyphenylsulfonic acid in yields between 66 and 76%. A mixture containing triisooctylammonium salts of sulfonated triphenylphosphite [TPPp-SO₃HN(i-octyl)₃] was submitted to a test for stability to hydrolysis. The time required for hydrolysis of 7.4% of the TPPp-SO₃HN(i-octyl)₃ was 3 hours under drastic conditions. Triphenylphosphite was in the same test hydrolyzed quantitatively within three hours. Tetradec-1-ene was hydroformylated by means of the catalytic systems consisting of rhodium-2-ethylhexanoate with either TPPp-SO₃HN(i-octyl)₃, triphenylphosphite (TPPp) or triphenylphosphine (TPP) at 125°C, 0.6 MPa and a rhodium concentration of 50 ppm. Higher reaction selectivities for linear aldehydes were achieved with the rhodium/TPPp-SO₃HN(i-octyl)₃ catalytic system. Reaction rates increased with the Rh/TPPp-SO₃HN(i-octyl)₃ catalyst at lower temperature (110°C). Using this catalyst at 110°C, higher yields are achieved than with the Rh/TPP or Rh/TPPp catalysts. Hex-1-ene was hydroformylated by using the catalytic systems Rh₄(CO)₁₂ with TPPp-SO₃HN(i-octyl)₃, Rh₄(CO)₁₂ TPP or Rh₄ (CO)₁₂ with TPPp at 125°C, 2,5 MPa and a rhodium concentration of 20 ppm. This confirms the above experiments which indicated that higher linear: branched aldehyde ratios were obtained with the rhodium/TPPp-SO₃HN(i-octyl)₃ catalyst.