Non-Invasive and Confirmatory Differentiation of Hermaphrodite from Both Male and Female Cannabis Plants Using a Hand-Held Raman Spectrometer

Cannabis (Cannabis sativa L.) is a dioecious plant that produces both male and female inflorescences. In nature, male and female plants can be found with nearly equal frequency, which determines species out-crossing. In cannabis farming, only female plants are preferred due to their high yield of cannabinoids. In addition to unfavorable male plants, commercial production of cannabis faces the appearance of hermaphroditic inflorescences, species displaying both pistillate flowers and anthers. Such plants can out-cross female plants, simultaneously producing undesired seeds. The problem of hermaphroditic cannabis triggered a search for analytical tools that can be used for their rapid detection and identification. In this study, we investigate the potential of Raman spectroscopy (RS), an emerging sensing technique that can be used to probe plant biochemistry. Our results show that the biochemistry of male, female and hermaphroditic cannabis plants is drastically different which allows for their confirmatory identification using a hand-held Raman spectrometer. Furthermore, the coupling of machine learning approaches enables the identification of hermaphrodites with 98.7% accuracy, whereas both male and female plants can be identified with 100% accuracy. Considering the label-free, non-invasive and non-destructive nature of RS, the developed optical sensing approach can transform cannabis farming in the U.S. and overseas.     

Quantum Crystallography and Complementary Bonding Analysis of Agostic Interactions in Titanium Amides

Agostic interactions involving titanium are textbook examples for C−H bond activation. Therefore, it is surprising that there is no study in the literature in which the hydrogen atom in the C−H⋅⋅⋅Ti interaction has been determined reliably, although nearly all the criteria for assessing the strength and character of the agostic interaction depend on the hydrogen atom and its position. Here, we demonstrate with quantum crystallographic techniques how hydrogen atoms in a series of three titanium amides can indeed be localized accurately and precisely based on routine single-crystal X-ray diffraction data. Once the hydrogen positions have been established, theoretical and experimentally fitted bonding analyses reveal that the C−H⋅⋅⋅Ti interaction becomes stronger with increasing inter-ligand London dispersion stabilization of bulky alkyl groups.     

The effect of polymer network structure on diffusive transport across chemically controlled membranes

This paper focuses on the relationship between diffusive transport and membrane composition (crosslinker content and relaxed polymer volume fraction) in membranes whose permeability can be actively controlled by chemical or electrical stimuli. First, pH induced changes in permeability to uncharged fluorescent solutes were measured. Then, by correlating bath pH with membrane hydration, the transport properties of membranes of different crosslinker content and/or relaxed polymer volume fraction were compared at constant hydration. The membrane permeability was found to decrease as the amount of crosslinker added to the membrane formulation at the time of polymerization increased, while the permeability increased as the solvent content during polymerization increased. A free volume theory which was fit to the data shows good agreement, and predicts a monotonically decreasing porosity factor with increased crosslinker content.     

Preparation of filled temperature-sensitive poly(N-isopropylacrylamide) gel beads

Temperature-sensitive filled poly(N-isopropylacrylamide) (PNIPAAm) gel beads with diameters in the range of millimeters were prepared using the alginate technique. The polymerization and cross-linking reaction of NIPAAm in the presence of inorganic filling particles was performed in spherical networks of Ca-alginate forming interpenetrating networks (IPN). Thermo-sensitive gel beads could be obtained by washing these IPN with EDTA solution. The PNIPAAm gel beads were analyzed by optical methods to observe there swollen diameter in dependence on the temperature. The diameters of the swollen gel beads were in the range of 0.1 - 2 mm. The influence of the monomer to cross-linker ratio (MCR) and the filling materials (ferrofluid, BaTiO₃, TiO₂, and Ni,) were studied. The phase transition temperature (T_pt) was only weakly influenced by the MCR and the filling material remaining at around 34°C.     

Enantioselective Nickel-Catalyzed Hydrocyanation of Homostilbenes

We investigated the previously unknown enantioselective Ni-catalyzed hydrocyanation of 1,3-diarylpropenes (homostilbenes). For this purpose, a series of (E)-homostilbenes were prepared by (microwave-assisted) Pd-catalyzed coupling of allylic alcohols with aryl-boronic acids. Employing our established catalyst system formed from Ni(cod)₂ and a TADDOL-derived chiral phosphine-phosphite ligand and using TMSCN as an in situ source of HCN, the hydrocyanation of various homostilbenes was studied. The synthetic usefulness of the methodology was demonstrated in a short synthesis of the new (allo-) colchicine analogue 7-cyano-11-methoxy-colchinol involving an PIDA-mediated oxidative cyclization of the corresponding hydrocyanation product to set up the 7-membered ring. The absolute configuration of 2,4-diphenylbutyronitrile was assigned by comparison of experimental and calculated ECD spectra.     

Mucin-Inspired Single-Chain Polymer (MIP) Fibers as Potent SARS-CoV-2 Inhibitors

Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates ( MIP-1 ) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer ( MIP ) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC₅₀) inhibitory concentration (IC₅₀=10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers ( MIPs ) of varying fiber lengths.     

Electrical properties of σ-conjugated polymers with additives and their applications in sensors

The charge carrier transport in poly[methyl(phenyl)silylene] (PMPSi) proceeds predominantly along the σ-delocalized Si backbone with participation of interchain hopping and polaron formation. The charge carrier mobility increases with increasing electron affinity of acceptor dopands having zero dipole moments. On the other band, the hole drift mobility is influenced by the dipole moment of the dopand. The electrostatic charge-dipole interactions cause a broadening of the energy distribution of transport states, which results in a decrease in the charge carrier mobility. An addition of organic salts leads, under the conditions of increased humidity, to an increase in electrical conductivity and capacitance. This is demonstrated on the layers PMPSi/1,5-dimorpholino-1,5-diphenylpentamethinium perchlorate.     

Characterization of ultra‐thin polymer films by polarization modulation FTIR spectroscopy

Self assembly monolayers of octadecyltrichlorosilane Cl₃‐Si‐(CH₂)₁₇‐CH₃ and 17‐cyanopentadecyltrichlorosilane Cl₃‐Si‐(CH₂)₁₇‐CN on silicon wafers have been prepared by adsorption from solution. The molecular orientation within the monolayers was investigated by using Polarisation Modulation FTIR spectroscopy. Quantitative analysis reveals that both types of silanes – monofunctionalised and bifunctionalised – form highly ordered monolayers. A high degree of ordering as well as a small tilt angel of the molecular backbones with respect to the surface normal are indicated by the strength of the Si‐O‐Si stretching modes and the weakness of the CH₂ stretching modes. The decomposition of the terminal nitrile group of the substituted silane into a carboxyl group could be identified. The decomposition is caused by a high local HCl concentration, which develops upon binding of 17‐cyanopentadecyltrichlorosilane to the OH groups of the silicon surface.     

Reversible switching of protein uptake and release at polyelectrolyte multilayers detected by ATR-FTIR spectroscopy

The reversible switching of uptake and release of the proteins lysozyme (LYZ, IEP = 11.1) and human serum albumin (HSA, IEP = 4.8) at the surface attached polyelectrolyte multilayer (PEM) consisting of poly(ethylene-imine) (PEI) and poly(acrylic acid) (PAC) is shown. Protein adsorption could be switched by pH setting due to electrostatic interaction. Adsorption of positively charged LYZ at PEM-6 took place at pH = 7.3, where the outermost PAC layer was negatively charged. Complete desorption was obtained at pH = 4, where the outermost PAC layer was neutral. Additionally the charge state of the last adsorbed PAC layer in dependence of the pH of the medium could be determined in the ATR-FTIR difference spectra by the ν(COO⁻) and ν(C=O) band due to carboxylate and carboxylic acid groups. Adsorption of negatively charged HSA at PEM-7 was achieved at pH = 7.3, where the outermost PEI layer was positively charged. Part desorption was obtained at pH = 10, where the outermost PEI layer was neutral. PEM of PEI/PAC may be used for the development of bioactive and bionert materials and protein sensors.     

Conformational transitions and aggregations of regioregular polyalkylthiophenes

Diverse conformational transitions and aggregations of regioregular poly (3-alkylthiophene)s (PATs) in different environment have been studied by means of AFM and UV-vis-spectroscopy. In methanol, which is a non-solvent for both alkyl side groups and aromatic backbone at low polymer concentration, PATs chains fold into compact poorly ordered flat structures. At higher polymer concentration PATs molecules undergo 3D aggregation into near spherical particles. In hexane, which is a selective solvent for alkyl side chains, PATs molecules undergo ordered main-chain collapse followed by 1D aggregation. Concentration-independent red shift of λmax and good resolved fine vibronic structure in the electronic absorption spectra indicate that planarization occurs on the single-molecule level.