Optimisation of nitrogen management after harvest of the main crop by growing turnips [<i>Brassica rapa </i>L. ssp. <i>rapifera</i> (Metzg.) Sinsk.] as a catch crop and field vegetable

The objective of the present study was to investigate whether the short growing season after the harvest of potatoes (PO) and faba beans (FB) enables to grow a marketable crop that can at the same time reduce soil nitrate concentration. For that reason turnips (Brassica rapa L. ssp. rapifera (Metzg.) Sinsk.) grown as field vegetables were investigated in order to determine their nitrogen sink capacity, nitrogen export with marketable roots and precrop effect on following wheat crop. A 2-years field experiment (1999-2001) was conducted on brown alluvial loamy-silty to sandy-silty soils of the organically managed experimental farm Wiesengut near Bonn, Germany (7 17' E, 50 48' N). The experimental design was a Latin Square with four replications. Single plot size was 6 x 12 m. The amount of soil nitrate after harvest of PO and FB reached up to 120 and 88 kg NO3--N ha-1 in the upper 90 cm soil depth, respectively. Turnips cv. 'Market Express F1' (Me), 'Petrowski' (Pe) and reference crop white mustard cv. 'Zlata' (Wm), were sown immediately after harvesting the main crops. Bare fallow (F) was used as a control. In both years after PO and FB, 100 days after sowing, Me, Pe and Wm took up 57 - 101, 60 - 120 and 73 - 207 kg N ha-1 respectively, thus reducing soil nitrate content up to 105 kg NO3--N ha-1 compared with F. DM yield of turnip roots (1.13 - 1.66 t ha-1) represented 40 to 65 % of total DM yield, containing between 32 and 60 % (34 - 53 kg N ha-1) of all accumulated nitrogen. Catch crops decreased grain yield of following winter wheat between 6 - 17 % compared to F and the total N uptake of winter wheat grown after catch crops was reduced up to 29 kg N ha-1. However decrease in total DM yield of wheat and corresponding N uptake were not influenced by N export of 34 - 53 kg N ha-1 from the field with turnip roots in autumn. When catch crops were left on the field during the winter and incorporated in spring at seed bed preparation an increase in spring wheat grain yield between 2 - 29 % and increase in total N uptake of 39.6 kg ha-1 compared to bare fallow were recorded. Export of nitrogen with roots of turnip Pe in spring ranging between 22 and 60 kg N ha-1 decreased DM grain yield of spring wheat by 1 - 17 % and reduced its total N uptake up to 26 kg ha-1. Generally, the positive precrop effect of catch crops on spring wheat was in the following order Wm > Me > Pe. Catch crops significantly influenced mineralization-immobilisation processes in the soil. Thus in autumn up to 135 kg ha-1 more nitrogen was determined in the plant - soil system when brassica catch crops were grown compared to bare soil. These results demonstrate that in a short growing period, after harvest of PO and FB, turnips can successfully be grown as field vegetables and as catch crops. Turnips produce a notable amount of marketable roots and are able to significantly reduce the soil nitrate content.Optimierung des Stickstoffmanagements nach der Ernte der Hauptfrucht durch Stoppelrüben [Brassica rapa L. ssp. rapifera (Metzg.) Sinsk.] als Zwischenfrucht und Feldgemüse Mit der vorliegenden Arbeit wurde untersucht, ob in der kurzen Vegetationszeit nach der Ernte von Kartoffeln (PO) und Ackerbohnen (FB) eine marktfähige Nachfrucht produziert und gleichzeitig die Bodennitratgehalte reduziert werden können. Dazu wurden Stoppelrüben (Brassica rapa L. ssp. rapifera (Metzg.) Sinsk.) als Feldgemüse angebaut und die Stickstoff-Aufnahmekapazität, der Stickstoff-Export über die marktfähigen Rüben und die Vorfruchteffekte zu Weizen in einem zweijährigen Feldexperiment (1999-2001) auf lehmig-schluffigen bis sandig-schluffigen Auensedimenten auf der organisch bewirtschafteten Lehr- und Forschungsstation Wiesengut in der Nähe von Bonn, Deutschland (7 17' E, 50 48' N) untersucht. Die Versuchsparzellen in der Größe von 6 x 12 m wurden als lateinisches Quadrat mit vier Wiederholungen angelegt. Der Nitratgehalt im Boden erreichte nach der Ernte in 0 - 90 cm Bodentiefe nach PO bis zu 120 kg NO3--N ha-1 und nach FB bis zu 88 kg NO3--N ha-1. Als Vergleich wurden Stoppelrüben der Sorten 'Market Express F1' (Me), 'Petrowski' (Pe) und Weisser Senf der Sorte 'Zlata' (Wm) unmittelbar nach der Ernte der Hauptfrüchte gesät. Schwarzbrache (F) diente als Kontrollvariante. In beiden Jahren wurden nach PO und FB in den ersten 100 Tagen nach der Saat durch Me 57 - 101 kg N ha-1, durch Pe 60 - 120 kg N ha-1 und durch Wm 73 - 207 kg N ha-1 aufgenommen, wodurch die Bodennitratgehalte auf 105 kg NO3--N ha-1 im Vergleich zu F reduziert wurden. Die Trockenmassenerträge der Stoppelrübenwurzeln (1,13 – 1,66 t ha-1) repräsentierten 40 bis 65 % der gesamten Trockenmasse und enthielten 32 - 60 % (34 - 53 kg N ha-1) des gesamten aufgenommenen Stickstoffs. Die Zwischenfrüchte reduzierten die Kornerträge des nachfolgenden Winterweizens zwischen 6 - 17 % verglichen mit F. Die N-Aufnahme von Winterweizen wurde nach den Zwischenfrüchten bis zu 29 kg N ha-1 reduziert. Allerdings war die Reduktion des Trockenmassenertrages und der entsprechenden N-Aufnahme nicht durch den N-Export durch die Rüben im Herbst (34 - 53 kg N ha-1) beeinflusst. Verblieben die Zwischenfrüchte über Winter auf den Parzellen und wurden im Frühjahr bei der Saatbeetbereitung eingearbeitet, wurde eine Erhöhung der Sommerweizenerträge zwischen 2 - 29 % und ein Anstieg der Gesamtstickstoffaufnahme bis zu 40 kg ha-1 verglichen mit der Schwarzbrache festgestellt. Der Stickstoffexport im Frühjahr durch Rüben der Sorte Pe (22 - 60 kg N ha-1) reduzierte den Ertrag von Sommerweizen zwischen 1 - 17 % und die gesamte N-Aufnahme bis zu 26 kg ha-1. Generell nahm der positive Vorfruchteffekt der Zwischenfrüchte zu Sommerweizen in der Reihenfolge Wm > Me > Pe ab. Die Zwischenfrüchte zeigten signifikante Einflüsse auf Mineralisations- und Immobilisierungsprozesse im Boden. Dementsprechend war nach Brassiceen-Zwischenfrüchten im Vergleich zur Schwarzbrache im Herbst bis zu 135 kg ha-1 mehr N im System Pflanze-Boden. Somit können Stoppelrüben in der kurzen Wachstumsperiode nach der Ernte von PO und FB erfolgreich als Feldgemüse und Zwischenfrüchte angebaut werden. Dabei wird eine bemerkenswerte Menge an markfähigen Rüben produziert und gleichzeitig der Bodennitratgehalt im Vergleich zur Schwarzbrache signifikant reduziert

Synthesis and properties of degradable and related polymers

V obdobju, ko se zavedamo pomembnosti trajnostnega razvoja, so pereča tematika polimeri. To delo se posveča sintezi polienaminonov in poliuretanov ter razgradnji oziroma recikliranju le teh. Polienaminone smo sintetizirali po novejši metodi iz bisenaminonov in soli aromatskih aminov z vinilogno nukleofilno substitucijsko polimerizacijo. Dobljene oligomere in polimere enaminonskega tipa smo okarakterizirali z 1H NMR in IR spektroskopijo ter določili karakteristike molekulskih mas. Sledilo je kemijsko recikliranje pri povišani temperaturi ob presežnem dimetilaminu v etanolu. Po štirih dneh razgradnje smo ločili komponente reakcijske zmesi in dobili visoke izkoristke recikliranja. Opazili smo spontano polimerizacijo v trdnem, če smo razgradne produkte pustili stati pri sobni temperaturi 24 h. Poliuretane smo sintetizirali v trdnem iz diizocianatov in poliolov v prisotnosti katalizatorja z adicijsko polimerizacijo. Nabor polimerov smo okarakterizirali z 1H NMR spektroskopijo, IR spektroskopijo in elementno analizo. Izvedli smo primerjalne teste biorazgradljivosti z respirometri, pri čemer smo uporabili asimilirane bakterije za hitrejšo razgradnjo. Sintetizirane polimere smo primerjali z referencami, ki niso biorazgradljive in opazili relativno povečanje razgradljivosti. Zanimali so nas termični razgradni produkti in obnašanje polimera ob povišanju temperature, zato smo izvedli Py-GC/MS in DSC meritve. Vsi polimeri so razpadli na izhodne diizocianate, fragmente poliolov in alifatske amine. Pri večini produktov smo opazili steklast prehod pri temperaturi pod 150 °C, le v enem primeru smo opazili tališče.Reflecting on the importance of sustainable development, polymers are a major issue. This work focuses on the synthesis, decomposition and recycling of polyenaminones and polyurethanes. Polyenaminones were synthesized by a relatively new method from bisenaminones and aromatic diamine salts by vinylogous nucleophilic substitution polymerization. The obtained oligomers and polymers of enaminone type were characterized by 1H NMR and IR spectroscopy and molecular characteristics were determined. Chemical recycling was carried out at elevated temperature with excess dimethylamine in ethanol. Depolymerization products were separated and high recycling yields were obtained. Spontaneous polymerization in solid was observed if the evaporated reaction mixture was allowed to stand at room temperature for 24 h after depolymerization. Polyurethanes were synthesized in solid from diisocyanates and polyols in the presence of a catalyst by addition polymerization. The polymers were characterized by 1H NMR spectroscopy, IR spectroscopy and elemental analysis. Comparative biodegradability tests with respirometry were performed. Assimilated bacteria were used for faster degradation. We compared the synthesized polymers with classic non-biodegradable polymers and observed a high relative increase in degradability. We were also interested in thermal decomposition products and the behavior of the polymer with increasing temperature, so we performed Py-GC/MS and DSC measurements. All polymers decomposed into the starting diisocyanates, polyol fragments and aliphatic amines. In most products, a glass transition at temperatures below 150 °C was observed, only in one case a melting point appeared

Sustainable in-water synthesis of aliphatic porous polyazines

Access to conjugated porous polymers via synthetically sustainable and straightforward routes is highly desirable, as many polymer systems exhibit high performance but require arduous synthetic protocols that rarely pave the way to commercial reality. In this article, we describe an easily fabricated series of novel highly porous poly(Schiff bases) that feature an aliphatic conjugated backbone obtained with low synthetic complexity from simple reagents such as glyoxal and hydrazine monohydrate in water. The effective synthesis enables the preparation of three different functional scaffolds, i.e., aerogels, polyHIPEs (polymerized HIPEs), and even carbon foams from aliphatic poly(azine) (PAZ) networks. The reported synthetic approach is compared to the literature using ″green chemistry metrics″, such as the E-factor and synthetic complexity (SC) index, and shows dramatic improvements. An E-factor of up to 0.27 for aerogels or 80 for polyHIPEs and an SC index of 2.7 are much lower than those for poly(arylene)-based conjugated analogues, indicating good scalability, sustainability, and low cost. PAZ materials feature impressive red/near IR-shifted optical absorption band edges, with an electrochemical band gap of 1.45 eV. Aliphatic PAZ scaffolds are characterized by high flexibility compared to aromatic analogues and do not fail at compressive loads of up to 70%. Finally, carbonization at 500 °C leads to highly porous carbonaceous scaffolds with a high N content of up to 29 wt % (21 mmol of nitrogen per gram carbon material)

Optimization method based on simplex for surface area improved photocatalytic performance of ▫g−C3N4g-C_3N_4▫

The main objective of the present study was to increase the specific surface area (SBET) of graphitic carbon nitride (g-C3N4) prepared from dicyandiamide by effectively modifying the synthesis procedure using the Simplex optimization method. A remarkable increase in SBET was achieved in only a few steps, with the highest value of 86 m2/g. Compared to the reference material, the improved photocatalyst exhibited enhanced and unique structural, textural, optical, and electronic properties, reflected in the improved ability of the photocatalyst to degrade a variety of organic pollutants dissolved in water. By performing scavenger and spin-trapping experiments, it was confirmed that the major reactive oxygen species formed under visible-light illumination of the enhanced photocatalyst were singlet oxygen (1O2) and superoxide anion radicals (O2–•) with a purposed formation mechanism. The enhanced formation of 1O2 enabled high activity and stability of the optimized materials as well as selective response to degradation of the pharmaceutical compounds studied. By using the simple and fast Simplex optimization algorithm to determine new synthesis parameters, we obtained an improved g-C3N4 that completely degrades bisphenol A under the conditions studied

Additive-manufactured anisotropic magnets for harsh environments

We describe the fabrication of SrFe12O19-based filaments, using polyphenylene sulphide (PPS) as the binder for the magnetic particles, and the subsequent printing of this filament with a 3D printer. PPS is an ideal polymer for applications in harsh environments, making it applicable for the automotive industry, where it is widely used with injection moulding. However, 3D printing this polymer introduces a major challenge. Because PPS is more difficult to extrude than polyamide, the filling factor in this study was set to 70 wt. %, which is lower than when used in injection moulding (close to 90 wt. %). The filament with a diameter of 2.75 mm was printed into a disk-shaped magnet with a diameter of 10 mm and a height of 4 mm using a HAGE 3D printer that uses a belt system for the filament extrusion. The magnets were printed onto a glass surface and onto a bulk Nd-Fe-B permanent magnet with an external magnetic field, parallel to the printer’s z-axis. Printing in the presence of a magnetic field was found to increase the magnet’s remanent magnetization by 61%, compared to an isotropic print. Without an external magnetic field we achieved a remanence of 23.9 emu/g for the 70 wt.% filling fraction, while when printing in a magnetic field, the value of the remanence improved to 39.7 emu/g because of the improved magnetic texture

Highly porous polymer beads coated with nanometer-thick metal oxide films for photocatalytic oxidation of bisphenol A

Highly porous metal oxide−polymer nanocomposites are attracting considerable interest due to their unique structural and functional features. A porous polymer matrix brings properties such as high porosity and permeability, while the metal oxide phase adds functionality. For the metal oxide phase to perform its function, it must be fully accessible, and this is possible only at the pore surface, but functioning surfaces require controlled engineering, which remains a challenge. Here, highly porous nanocomposite beads based on thin metal oxide nanocoatings and polymerized high internal phase emulsions (polyHIPEs) are demonstrated. By leveraging the unique properties of polyHIPEs, i.e., a three-dimensional (3D) interconnected network of macropores, and high-precision of the atomic-layer-deposition technique (ALD), we were able to homogeneously coat the entire surface of the pores in polyHIPE beads with TiO$_2$-, ZnO-, and Al$_2$O$_3$-based nanocoatings. Parameters such as nanocoating thickness, growth per cycle (GPC), and metal oxide (MO) composition were systematically controlled by varying the number of deposition cycles and dosing time under specific process conditions. The combination of polyHIPE structure and ALD technique proved advantageous, as MO-nanocoatings with thicknesses between 11 ± 3 and 40 ± 9 nm for TiO$_2$ or 31 ± 6 and 74 ± 28 nm for ZnO and Al$_2$O$_3$, respectively, were successfully fabricated. It has been shown that the number of ALD cycles affects both the thickness and crystallinity of the MO nanocoatings. Finally, the potential of ALD-derived TiO$_2$-polyHIPE beads in photocatalytic oxidation of an aqueous bisphenol A (BPA) solution was demonstrated. The beads exhibited about five times higher activity than nanocomposite beads prepared by the conventional (Pickering) method. Such ALD-derived polyHIPE nanocomposites could find wide application in nanotechnology, sensor development, or catalysis

Synthesis of Optically and Redox Active Polyenaminones from Diamines and &alpha;,&alpha;&rsquo;-Bis[(dimethylamino)methylidene]cyclohexanediones

New oligo- and polyenaminones with Mw ~ 7&ndash;50 KDa were prepared in high yields by transaminative amino-enaminone polymerization of regioisomeric bis[(dimethylamino)methylidene]cyclohexanediones with alkylene and phenylenediamines. The polymers obtained are practically insoluble in aqueous and organic solvents and exhibit film-forming properties, UV light absorption at wavelengths below 500 nm, and redox activity. These properties indicate a promising application potential of these polymers, which could find use in optical and optoelectronic applications and in energy storage devices

supplementary_data_v1 - Time-Dependent Finite Element Analysis of <i>In Vivo</i> Electrochemotherapy Treatment

<p>supplementary_data_v1 for Time-Dependent Finite Element Analysis of <i>In Vivo</i> Electrochemotherapy Treatment by Matevž Pintar, Janez Langus, Ibrahim Edhemović, Erik Brecelj, Matej Kranjc, Gregor Sersa, Tomaž Šuštar, Tomaž Rodič, Damijan Miklavčič, Tadej Kotnik, and Bor Kos in Technology in Cancer Research & Treatment</p