Pyrolysis-gas chromatography/mass spectrometry analysis as a useful tool in forensic examination of automotive paint traces

Pyrolysis (Py)-GC/MS was applied in comparative analysis of polymer binder of 150 automobile clearcoat samples. It was found that binders of identical type and similar infrared spectra can be, in most cases, effectively differentiated, sometimes based only on the presence of peaks of very low intensity originating from minor paint components. The qualitative procedure of pyrograms comparison was developed. The results obtained, enable one to draw the conclusion that Py-GC/MS appears as valuable, very informative analytical technique of car paint samples examination. Providing identification of paint pyrolysis products, it enables discrimination of samples on the basis of their composition. However, in some cases, paint samples were still indistinguishable on the basis of their pyrograms.     

Synthesis of a stable iminium salt and propellane derivatives

The treatment of morphinan 1 with NaH and MsCl provided very stable iminium salt 7 possessing propellane skeleton. One of the synthesized iminium salts 7, isobutyl derivative 7b, was crystallized and its structure was determined by X-ray crystallography. The natural bond orbital analysis suggested that the stability of the iminium should result from the stereoelectronic effect (hyperconjugation) attributed to their own structures.     

Kinetic studies on the addition of phenol to S-phenyl-S-vinyl-N-p-tosylsulfilimine derivatives

The rate constants of nucleophilic addition of phenyl to vinylsulfilimine(VSI) and its derivatives were determined by an ultraviolet spectrophotometer at 25°C, and the rate equations which can be applied over a wide pH range were obtained. On the basis of the pH-rate profile, product analysis, general base catalysis, and the substituent effect, a plausible mechanism of this addition reaction was proposed: Below pH 3.0, the reaction proceeded via the addition of a neutral molecule to the carbon-carbon double bond after protonation at the nitrogen atom of the sulfilimine. Above pH 10.0, the addition of a phenoxide ion to the carbon-carbon double bond was rate controlling. However, in the pH range of 3.0 to 10.0, these two reactions occurred competitively.     

Counterexamples of continuous maps on dendrites

We take a list of properties of continuous maps on compact metric spaces, e.g. the existence of an arc horseshoe, the positivity of topological entropy, the existence of a homoclinic trajectory, the existence of an omega-limit set containing two minimal sets and others. Our aim is to find the relations between the properties in the case of dendrite maps. To achieve the aim at least partially, we consider several examples of dendrite maps and check which of the properties particular examples have. It also helps us to understand the dynamics of dendrite maps.     

Protein–Nanoparticle Interaction‐Induced Changes in Protein Structure and Aggregation

Large surface area, small size, strong optical properties, controllable structural features, variety of bioconjugation chemistries, and biocompatibility make many different types of nanoparticles (NPs), such as gold NPs, useful for many biological applications, such as biosensing, cellular imaging, disease diagnostics, drug delivery, and therapeutics. Recently, interactions between proteins and NPs have been extensively studied to understand, control, and utilize the interactions involved in biomedical applications of NPs and several biological processes, such as protein aggregation, for many diseases, including Alzheimer's disease. These studies also offer fundamental knowledge on changes in protein structure, protein aggregation mechanisms, and ways to unravel the roles and fates of NPs within the human body. This review focuses on recent studies on the roles and uses of NPs in protein structural changes and aggregation processes.     

Efficient Hole‐Transporting Materials with Triazole Core for High‐Efficiency Perovskite Solar Cells

Efficient hole‐transporting materials (HTMs), TAZ‐[MeOTPA]₂ and TAZ‐[MeOTPATh]₂ incorporating two electron‐rich diphenylamino side arms, through direct linkage or thiophen bridges, respectively, on the C3‐ and C5‐positions of a 4‐phenyl‐1,2,4‐triazole core were synthesized. These synthetic HTMs with donor–acceptor type molecular structures exhibited effective intramolecular charge transfer for improving the hole‐transporting properties. The structural modification of HTMs by thiophene bridging might increase intermolecular π–π stacking in the solid state and afford a better spectral response because of their increased π‐conjugation length. Perovskite‐based cells using TAZ‐[MeOTPA]₂ and TAZ‐[MeOTPATh]₂ as HTMs afforded high power conversion efficiencies of 10.9 % and 14.4 %, respectively, showing a photovoltaic performance comparable to that obtained using spiro‐OMeTAD. These synthetically simple and inexpensive HTMs hold promise for replacing the more expensive spiro‐OMeTAD in high‐efficiency perovskite solar cells.     

Co-sensitization of organic dyes for efficient ionic liquid electrolyte-based dye-sensitized solar cells

The co-sensitization of two organic dyes (SQ1 and JK2), which are complementary in their spectral responses, shows enhanced photovoltaic performance compared with that of an individual organic dye-sensitized solar cell. The power conversion efficiency of the co-sensitized organic dye solar cell based on the newly developed binary ionic liquid (solvent-free) electrolyte gives 6.4% under AM 1.5 sunlight at 100 mW/cm2 irradiation, which is higher than that of individual dye-sensitized solar cells. The incident monochromatic photon-to-current conversion efficiency (IPCE) of the co-sensitized solar cell shows typical absorption peaks at 530 and 650 nm corresponding to the two dyes and displays a broad spectral response over the entire visible spectrum with IPCE of >40% in the 400-700 nm wavelength domain.     

Template synthesis of a huge macrocycle by olefin metathesis using easily accessible [Pt(PEt(3))(2)] templates

We have reported the template synthesis of a 90-membered macrocycle by olefin metathesis. The macrocycle 7 was prepared by an initial six-oxidative-addition reaction of 2 by [Pt(PEt(3))(4)]. The definite structure of a six-oxidative product was confirmed by the crystal structure. The coordination of 2,6-bis(hex-5-enyloxy)pyridine to 3 led to the hexacationic aryl complex of type 4. The metathesis of olefin-substituted pyridine with Grubbs catalyst ([PhCH==RuCl(2)(Cy(3)P)(2)]) formed the expected macrocycle 5. The olefin metathesis reaction was formed under high dilution to suppress intermolecular olefin metathesis polymerization. The detachment of the newly formed macrocycle 6, followed by reduction to alkane macrocycle 7 by using palladium on charcoal and hydrogen led to a huge macrocycle. The mild and easy access of the template protocol opens a host of potential subsequent transformations toward the construction of a variety of macrocycles.     

Versatile flow injection manifold for analytical calibration

A flow injection calibration system, originally designed and tested in our laboratory, is presented here as a versatile analytical tool serving for calibration purposes. It is characterized by a simple construction, easy operation and the possibility of offering rich measurement information with the use of a single standard solution. It is shown that depending on instrumental conditions and the composition of the calibration solutions the manifold is able to realize various calibration procedures according to interpolative, extrapolative and integration modes. As an experimental example, the determination of calcium in the cabbage sample by flame atomic absorption spectrometry has been calibrated by means of dilution method (DM) in the integration mode.