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Synthesizing ring structure aviation fuels from biomass-derived platform molecules is challenging, especially for bridged ring structure aviation fuels which are typically achieved from fossil-derived chemicals. Herein, we report the synthesis of a series of ring structure biofuels in two steps by a combination of a solvent-free Michael-cyclization reaction and a hydrodeoxygenation (HDO) reaction from lignocellulose-derived 5,5-dimethyl-1,3-cyclohexanedione. These biofuels are obtained with high overall yields up to 90%, which exhibit high densities of 0.81 g cm−3-0.88 g cm−3 and high volumetric neat heat of combustion (VNHOC) values of 36.0 MJ L−1-38.6 MJ L−1. More importantly, bridged-ring structure hydrocarbons can also be achieved in two steps by a combination of a Robinson annulation reaction and an HDO reaction to afford the final products at high overall yields up to 90%. The bridged-ring structure products have comparable high densities and high VNHOC values to the best artificial fuel JP-10 (0.94 g cm−3 and 39.6 MJ L−1). The results demonstrate a promising way for the synthesis of high-density aviation fuels with different fuel properties at high yields.

The effects of the number of imidazoline ring and the length of alkyl group chain of imidazoline derivatives were investigated using quantum chemical calculation, molecular dynamics simulation and experimental techniques. Three corrosion inhibitors including Symmetrical lauric acid imidazoline (SAI), Tetracyclic lauric acid imidazoline (LAI), and Symmetric stearic acid imidazoline (SPI) were synthesized and their inhibition performance was evaluated using weight loss measurement, electrochemical techniques and surface characterization. The results show that SAI and LAI with the same length of alkyl group chain, LAI with more imidazoline rings could supply a better inhibition performance since the increase of active sites. The increase of active sites attached to the metal surface may also change the distribution of corrosion inhibitor, which could limit inhibition performance improvement. While, SAI and SPI with the same number of imidazoline rings, SPI with longer alkyl group chain shows a better inhibition efficiency due to the better hydrophobic performance of alkyl groups. Among the three inhibitors, SPI show the best inhibition performance, indicating that the alkyl group chain length affects the inhibition performance more obvious than the number of the imidazoline rings.

Two novel seco-polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperbenzones A (1) and B (2), were isolated from the roots of Hypericum beanii, together with one known biosynthetic congener 3. Compound 1 incorporates a 6/5/5 ring system with an unprecedented spiro[bicyclo[3.3.0]octane-3,1ʹ-cyclohexane]-2,2ʹ-dione motif. The structures of 1 and 2 were determined by a combination of high resolution electrospray ionization mass spectroscopy (HRESIMS), nuclear magnetic resonance (NMR) spectroscopic analyses, gauge-independent atomic orbital (GIAO) NMR chemical shift calculation with DP4+ analyses, electronic circular dichroism (ECD) calculation, and X-ray diffraction analysis. A 1,2-seco retro-Claisen rearrangement from a bicyclo[3.3.1]nonane PPAP precursor and following chemodivergent radical cascade cyclizations are proposed as the key steps in the biosynthetic pathway to yield compounds 1 and 2. Biological investigations indicated that compounds 1 and 3 could decrease intracellular lipid accumulation in a palmitic acid-induced nonalcoholic steatohepatitis (NASH) cell model.

A dynamic mechanical model is proposed to describe the complexing actions of all the rolls on the ring during the ultra-large radial-axial ring rolling (RARR) process with four guide rolls. Based on the model, the calculation models for bending moment and normal stress at any section of the ring are deduced by force method. If the maximum section bending normal stress exceeds the yield stress of the ring materials, the ring will be distorted thus leading to the instability of the RARR process. According to this, a plastic instability criterion for the ultra-large RARR process with four guide rolls is developed, based on which a mathematical model to calculate the critical guide force for avoiding plastic instability of ring is obtained. The influence rule of the position of guide roll on the dangerous ring section of plastic instability is revealed, from which it is found the dangerous ring section mainly appears at the radial and axial deformation regions and the contact positions of the guide rolls and ring. The optimized layout of guide roll around the ring in favor of stability is determined to be about α1=61° and α2=119°. The plastic instability criterion is proven to be reliable from the aspects of the critical guide force, the section bending moment and normal stress and the dangerous ring section of plastic instability. Intelligent simulation case studies for the RARR process of ultra-large aluminum alloy ring indicate that the stable forming of the process can be effectively realized by regulating the guide force based on the plastic instability criterion. This work could provide a valuable guidance for the control of guide rolls and the optimization of the ultra-large RARR process with four guide rolls.

A set of triethylammonium 4-oxo-6-pyridinethiolate–1,3,4-thiadiazoline hybrids (3a-e) were prepared via the reaction of ethyl 2-chloro-6-cyclopropyl-3- nitro-4-oxothieno[2,3-b]pyridine- 5-carboxylate (2) with the appropriate thiobenzoyl- hydrazide (1a-e) in acetonitrile and triethylamine. These hybrids were readily converted, under neutral mild conditions, into the corresponding 4-hydroxy-6-thioxopyridine –thiadiazoline hybrids (5a-e). The structures of the latter set are supported by HRMS, 1H NMR, and 13C NMR spectral data and further confirmed by single-crystal X-ray diffraction studies. Alkylation of these hybrids in the presence of triethylamine occurred exclusively at the 6-thioxosulfur, yielding the respective 6-sulfanyl derivatives (6a-c).

The cytosolic antibody receptor and RING E3 ligase TRIM21 targets intracellular, antibody-coated immune complexes for degradation and activates the immune system. Here we review how TRIM21 degrades diverse targets and how this activity can be exploited in molecular biology and for the development of new therapeutics. In addition, we compare what is known about TRIM21's mechanism to other TRIM proteins and RING E3 ligases.

Nowadays, low water-to-cement (w/c) ratio has been put into widespread use in engineering practice. However, low w/c ratio may give rise to high self-desiccation, which may lead to the decrease of early-age cracking resistance. Investigating the impact of w/c ratio on cracking resistance is utterly meaningful to better understand the cracking mechanism of concrete. However, the corresponding investigations remain lacking, especially when the ring test is utilized. In the present study, ring tests for three concrete mixtures with different w/c ratios were conducted to investigate the early-age cracking resistance of concrete from multiple parameters. Results showed that (i) the development rate of shrinkage of concrete for mixture W50 was slower than that for mixtures W33 and W40; (ii) the value and development rate of residual stress of concrete decreased when the w/c ratio increased; (iii) the relaxed stress for all mixtures developed rapidly at very early age, and reached the maximum value quickly; (iv) the cracking resistance of concrete increased when the w/c ratio increased at early age.

The photochemistry of aryl chlorides having a X-SiMe3 group (X = O, NR, S, SiMe2) tethered to the aromatic ring has been investigated in detail, with the aim to generate valuable ϭ,π-heterodiradicals. Two competitive pathways arising from the excited triplet state of the aromatics have been observed, namely heterolysis of the aryl–chlorine bond and homolysis of the X–silicon bond. The former path is found in chlorinated phenols and anilines, whereas the latter is exclusive in the case of silylated thiophenols and aryl silanes. A combined experimental/computational approach was pursued to explain such a photochemical behavior. Graphical abstract[Figure not available: see fulltext.]

Although fluorobis(phenylsulfonyl)methane (FBSM) and its cyclic analog 2-fluoro-1,3-benzodithiole-1,1,3,3-tetraoxide (FBDT) possess similar physicochemical properties, Shibata et al. found that FBSM failed to undergo nucleophilic monofluoromethylation of aldehydes regardless of the reaction conditions attempted (using various organic and inorganic bases). However, it was later discovered by Hu et al. that the nucleophilic monofluoromethylation could be accomplished by employing lithium hexamethyldisilazide (LiHMDS) as a base. Herein, we present an in-depth computational investigation into the intriguing effects of reagent structure and bases on the nucleophilic monofluoromethylation of aldehydes. The computations reveal the 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyzed nucleophilic monofluoromethylation of benzaldehyde with acyclic FBSM is a thermodynamically unfavorable process mainly due to the destabilizing O•••O lone pair repulsions in FBSM product, whereas such repulsion could be largely avoided in FBDT product because of its constrained five-membered ring structure. Employing LiHMDS as a base cannot only facilitate the nucleophilic monofluoromethylation via Li–O interactions but also render the monofluoromethylation of benzaldehyde with FBSM thermodynamically favored.

Since organoboron compounds readily undergo a diverse array of transformations and are widely used in various fields, the development of C–B-bond-forming reactions have attracted considerable atten...

With regard to the nature of their bonding and reactivity, fulvenes occupy a position intermediate between their benzenoid isomers and the olefins. The chemical and physical behavior of the fulvenes is determined either by the diene character of the cross-conjugated system or by the cylic conjugation in the five-membered ring, depending on the type of substituent at the exocyclic carbon atom. In addtion to several new substitution reactions, a description is given of the syntheses and reactions of 6-amino- and 6-hydroxyfulvenes, isomeric with anilines and phenols, the derivatives of which can be used for the preparation of new types of nonbenzenoid cyclic conjugated systems such as carbocyclic and heterocyclic azulenes, pseudoazulenes, thiepines, dihydropyridazines, and s-indacene.

N,O-heterocycles containing the dicarbonyl ring play a significant role in heterocyclic and therapeutic chemistry. Since the discovery of 1,3-diketones, numerous research works have been achieved regarding the synthesis and its chemical reactivity. In this review, we have described the most relevant publications involving β-diketone compounds published during the period between 2018 to date. In addition, we include the 1,3-diketones-based heterocyclic compounds prepared by various synthetic methodologies.

A unified protecting group-free approach to two stemarene and two betaerene diterpenoids through a bioinspired two-phase strategy has been developed, and three of them were obtained for the first t...

In this paper, we propose and theoretically design a highly sensitive refractive index (RI) sensor based on Vernier effect in three coupled micro-ring resonators (CMRR) with identical geometries. When the whispering gallery mode phases of different microresonators match with each other, transmittance of the CMRR increases and the envelope peak wavelength shift of the modulated spectrum could be exploited for wavelength-interrogated RI sensing based on Vernier effect. Further simulation results indicate that RI sensing could be achieved within a wide RI range of 1.33 to 1.43 by adjusting RI of the liquid kept inside the control cavity, and limitless sensitivity could be achieved for some specific RI ranges which are mainly determined by geometric parameters of the resonators and the order of selected envelope peak for sensing, making the sensor available for different sensing requirements. The proposed CMRR provides a compact, flexible and low-cost solution for biochemical sensing applications. And moreover, the proposed RI sensing range extension method as well as limitless sensitivity mechanism pave a new way toward the development of dynamic RI sensing and tunable optoelectronic devices.

Doping alkali metal atoms, especially lithium (Li), in nanocarbon materials has always been considered to be one of the most effective methods to improve the optical properties of the system. In this theoretical work, we doped a Li atom to the recently observed all-carboatomic molecule, cyclo[18]carbon (C18), and finally obtained two stable configurations with Li inside and outside the ring. The calculation results show that the energy barrier of transition between the two Li@C18 configurations is low, so the conversion is easy to occur at ambient temperature. Further study reveals that the state of Li@C18 complex, namely its dominant configuration, can be switched by applying a proper external electric field (EEF). The electronic structure, absorption spectrum, and optical nonlinearity of the two configurations are found to be significantly different, which indicates that the optical properties of the Li@C18 complex can be effectively regulated by switching the location of doped Li atom between inside and outside the carbon ring. With the help of various wavefunction analysis methods, the nature of the discrepancies in the properties of Li@C18 complex with different configurations was deeply revealed. The relevant results are expected to provide theoretical guidance for development of cyclocarbon-based optical molecular switches.

In this paper, we developed an electrophilic ring-opening reaction, which is beyond the strained small ring system. Under reductive nickel catalysis, ring-opening of diverse benzofurans via endocyc...

This work detailed the preparation of a class of water-soluble PNP ligands that differed by the nature of the substitute on phenyl ring of ligands. These ligands were incorporated into water-soluble rhodium-PNP complex catalysts that were used to regioselective hydroformylation of a series of terminal arylalkenes, providing efficient access to rac-α-aryl propionaldehydes in good to excellent yield (up to 97%) and branched-regioselectivity (up to 40:1 b/l ratio). Furthermore, gram-scale and diverse synthetic transformation demonstrated synthetic application of this methodology for non-steroidal antiinflammatory drugs.

With the increasing demand for synthetic rubber, the purification of 1,3-butadiene (C4H6) is of great industrial significance. Herein, the successful removal of n-butene (n-C4H8) and iso-butene (iso-C4H8) from 1,3-butadiene (C4H6) was realized by synthesizing a novel TaOF52– anion-pillared ultramicroporous material TaOFFIVE-3-Ni (also referred to as ZU-96, TaOFFIVE = TaOF52–, 3 = pyrazine). Single-component adsorption isotherms show that TaOFFIVE-3-Ni can achieve the exclusion of n-C4H8 and iso-C4H8 in the low pressure region (0–30 kPa), and uptake C4H6 with a high capacity of 92.78 cm3·cm–3 (298 K and 100 kPa). The uptake ratio of C4H6/iso-C4H8 on TaOFFIVE-3-Ni was 20.83 (298 K and 100 kPa), which was the highest among the state-of-the-art adsorbents reported so far. With the rotation of anion and pyrazine ring, the pore size changes continuously, which makes smaller-size C4H6 enter the channel while larger-size n-C4H8 and iso-C4H8 are completely blocked. The excellent breakthrough performance of TaOFFIVE-3-Ni shows great potential in industrial separation of C4 olefins. The specific adsorption binding sites within ZU-96 was further revealed through the modeling calculation.

As one of the specific biomarkers of anthrax, timely, sensitive and accurate detection of 2,6-dipicolinic acid (DPA) plays an important role in preventing biological weapons attacks and disease outbreaks. Here, multiemission Eu3+/covalent- organic framework (COFDTA-TFP) and Tb3+/COFDTA-TFP were constructed by the coordination between Eu3+ or Tb3+ with fluorescent COFDTA-TFP which was prepared by amine-aldehyde dehydration condensation between 2,5-diaminoterephthalic acid and 2,4,6-triformylphloroglucinol for the first time. The Eu3+/COFDTA-TFP and Tb3+/COFDTA-TFP can emit non-overlapping fluorescence of COFDTA-TFP and Eu3+ or Tb3+, which was used to ratiometric detection of DPA. Due to the strong coordination between the nitrogen atoms in the pyridine ring and the oxygen atoms in the carboxyl group of DPA with Eu3+ or Tb3+, DPA replaced coordinated H2O to sensitize fluorescence of Eu3+ or Tb3+ by “antenna” effect but fluorescence of COFDTA-TFP with two-dimensional lamellar structure was kept constant as a reference. The linear range and detection limit of ratiometric fluorescence sensor based on Eu3+/COFDTA-TFP for detection of DPA are 0.01–12 µM and 4.2 nM, respectively. The linear range and detection limit of ratiometric fluorescence sensor based on Tb3+/COFDTA-TFP for detection of DPA are 0.01–9.0 µM and 2.9 nM, respectively.

Background: Heterocyclic compounds display versatile biological applications, so the aim of this paper was to prepare biologically important heterocycles with enhanced bacterial resistance and to evaluate for their various structural features that are responsible for their biological properties. Objective: The objective was to synthesize bacterial resistance compounds with enhanced antibacterial properties. Method: Ester moiety containing thiazole ring was converted into its hydrazide derivatives. These heterocyclic derivatives were cyclized into another ring oxadiazole; hence a hybrid ring system of two biologically active rings was prepared. Result: All the synthesized compounds were characterized by spectroscopic techniques and were screened for their antibacterial potential; they possess significant antibacterial activities. Conclusion: New hybrid heterocyclic ring systems were synthesized by cyclization of hydrazide derivatives by adopting two step strategy in good yields. All the synthesized compounds were evaluated for their antioxidant activities; they showed moderate to significant activities. QSAR and Molecular docking studies were performed to determine the mode of interaction. Experimental and computational data is in accordance with the determined antibacterial activities.

The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and Ni-Mn-Ga alloys during directional solidification is investigated experimentally and numerically. It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field. For the Al-Cu and Ni-Mn-Ga alloys, the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10 μm/s and 5 μm/s. Further, the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated. Numerical results reveal that the rotary thermoelectric (TE) magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field. This flow will induce the formation of the ring-like macro-segregation and structure. Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results. Therefore, the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.

Мета — встановити особливості імуноморфофункціональної організації аденоїдів у дітей з гіперплазією лімфоглоткового кільця. Обстежено 54 дитини (довільна вибірка) віком від 3 до 7 років із приводу гіпертрофії глоткової мигдалини. Серед 54 відібраних дітей було 28 (52 %) хлопчиків і 26 (48 %) дівчаток. Приводом до оперативного видалення аденоїдів слугувала неефективність консервативної терапії. Матеріалом для морфологічного дослідження були аденоїди дітей, отримані після аденоїдектомії. Під час аналізу анамнестичних даних 54 дітей з аденоїдною вегетацією віком від 3 до 7 років було виявлено, що серед пацієнтів із цією патологією переважали пацієнти віком 4–6 років. Ступінь гіпертрофії глоткової мигдалини був найбільший серед дітей дошкільного віку. Морфометричне дослідження аденоїдів виявило реципрокні стосунки («ножиці») між відносними площами фолікулярної і дифузної лімфоїдної тканини зі зниженням протяжності зони лімфоепітеліального симбіозу і збільшенням протяжності респіраторного епітелію при збереженні локальних реактивних ділянок.

Lewis-acid mediated allylations of β-alkoxy N-tosyl imines lead to 3-alkoxy homoallylic N-tosyl amines with anti diastereoselectivity. Diastereoselectivity and yields of reactions are comparable between two methods of Hosomi-Sakurai allylations. Observed selectivity trends and computational evidence suggest that 1,3 asymmetric induction occurs through the formation of a six- membered ring chelate which adopts a half-chair-like conformation. The product ratios of allylations to β-alkoxy N-tosyl imines are dependent on conformation preferences of the chelate and stereoelectronic interactions in the transition-state structures. Debenzylation and detosylation of these allylation products result in anti 1,3-amino alcohols, a privileged motif in synthetic and natural bioactive compounds.

A synthetic approach towards 6H-benzo[c]chromene ring under visible light and transition-metal-free conditions has been developed. Benzochromenes are synthesized from the corresponding (2-halobenzyl) phenyl ethers or (2-halophenyl) benzyl ethers using KOtBu in dimethyl sulfoxide (DMSO) at room temperature (rt) and blue light-emitting diodes (LEDs) as light source. This methodology replaces the use of ligands or additives, high temperatures and toxic solvents. The photostimulated reaction exhibits very good tolerance to different functional groups and 5H-dibenzo[c,f]chromenes are also effectively obtained. An electron donor-acceptor complex formed by the dimsyl anion and (2-halobenzyl) phenyl ethers was found and induces the ET as the initial step in the photocyclization reaction. Furthermore, in order to explain the regiochemical outcome of this reaction, a theoretical analysis was performed with DFT methods.

One organic functional group was introduced to distinguish the four phenyl ring of tetraphenylethylene, and the In situ temperature-dependent crystal structures were determined to exhibit the conformation changes of tert-butyl (3-(1,2,2-triphenylvinyl)phenyl)carbamate (denoted as BTPC). The isotropic displacement parameters of each phenyl further confirm the inequivalent vibrations of molecule resulted from the anisotropy of crystal.

Background/Aim. The relationship between the foveal avascular zone (FAV) and visual acuity (VA) in retinal dis-eases remains a matter of discussion. The aim of this study was to determine the impact of diabetic macular ischemia (DMI) on VA through the analysis of the perifoveal capillary network in various stages of diabetic retinopathy - DR (non-proliferative diabetic retinopathy ? NPDR and proliferative diabetic retinopathy ? PDR). Methods. Qualitative and quantitative analysis of 143 angiograms of patients with different stages of DR was performed. The degree of macular ischemia was assessed by the analysis of 2 parameters: perifoveal capillary ring, ie, the FAZ outline irregularity, and capillary loss. Finally, a comparison was made between the degree of macular ischemia with the best-corrected VA, depending on macular thickness. Results. In the eyes with mild and moderate NPDR, without significant macular thickening, no statistically significant decrease in VA caused by macular ischemia was noticed (p = 0.81). Opposite, in a subgroup with severe NPDR and PDR, without significant macular thickening, a statistically significant difference was presented among eyes with moderate and severe macular ischemia compared to eyes with lower grades of macular ischemia (p = 0.021 and p = 0.018, respectively). In the eyes with moderate NPDR and mild macular ischemia, the increase in macular thickness resulted in a statistically insignificant decrease in VA compared to eyes with a normal macular thickness (p = 0.088). However, in the eyes with severe NPDR, every pathological increase in macular thickness caused a statistically significant decrease in VA, regardless of the degree of macular ischemia (p = 0.018?0.040). A similar relationship was also found in the eyes with PDR (p = 0.017?0.042). In the eyes with a statistically significant decrease in VA, most of the examined eyes (98%) had the FAZ outline irregularity in the nasal perifoveal subfield. Conclusion. In the absence of significant macular thickening, the destruction of one-half of the perifoveal capillary network, or greater, is associated with reduced VA. The location of macular ischemic changes in the nasal parts of the perifoveal capillary ring plays a crucial role in its effects on visual function.

Polycyclic aromatic hydrocarbons (PAHs) as a typical class of organic semiconductors demonstrate unique optical, electrical, magnetic and other interesting properties due to their extended conjugation and diverse structures.

Summary A majority of medicines contain a nitrogen atom within a five- or six-membered ring. To rapidly access both such aza-heterocycles, we sought to develop a remote C–H desaturation of amines. Inspired by the Hofmann-Loffler-Freytag (HLF) synthesis of five-membered pyrrolidines, we tackled the century-old challenge of synthesizing six-membered piperidines by H-atom transfer. Herein, we present a double, vicinal C–H oxidation by dual catalysis, entailing Ir photocatalytic initiation of 1,5-HAT by an N-centered radical and Cu-catalyzed interception of the C-centered radical to facilitate desaturation. By this mechanism, two C–H bonds (δ and e to N) are regioselectively removed from unbiased, remote positions of an alkyl chain. Over 50 examples illustrate the efficiency, selectivity, functional group tolerance, and medicinal utility of the synthesis of both internal and terminal δ vinylic amines and aza-heterocycles. Mechanistic experiments probe the alkylcopper intermediate, as well as the kinetics and regioselectivity of the HAT and elimination steps.

Exploring the initial reactions of H-free and nitro-free energetic materials could enrich our understanding into the thermal decomposition mechanism of various energetic materials (EMs). In this work, two furoxan compounds, 3,4-dinitrofurazanfuroxan (DNTF) and benzotrifuroxan (BTF), were investigated to shed light on the decay mechanism of furoxan compounds based on the self-consistent charge density functional tight binding molecular dynamic simulations. Results show that DNTF and BTF decay in a unimolecular mechanism, and the transformation of furoxan ring to nitro group are suggested as a novel initial channel. Five initial steps of DNTF are observed, including NO2 loss and the N(O)-O bond cleavage of central and peripheral rings. The bond cleavage of peripheral rings dominates the decay at low temperature, while the central ring opening and C-NO2 dissociation governs the high temperature decay. Besides, NO2, CO and NO fragments are mainly yield at high temperature, while CO3N2 is dominant at low temperature. The three-stage characteristics of the exothermic of BTF decay are described under programmed heating conditions for the first time. Four initial steps of BTF were identified, including furoxan ring opening reactions and the breakage of 6-membered ring C-C bond. The cleavage of N(O)-O bond rules the initial step of BTF under different heating conditions, and the frequency increased with the temperature increasing. In addition, the amount of CON, ON and CO are higher at high temperature, while C2O2N2 shows a opposite trend. What obtained this work promote deepen insights into the complicated sensitivity mechanism of EMs.

Based on the hole-drilling strain sensing method, a ring Fiber Bragg Grating (FBG) array is proposed to realize comprehensive and convenient measurement of residual stress for homogeneous or inhomogeneous materials. All FBG sensors are arranged tangentially along the edge of the ring. With the ring array around the drilled hole, more detailed information of the residual stress can be obtained such as the location and the degree of inhomogeneity. The tangential arrangement of FBG sensors can achieve comparable measurement results to the radial arrangement but it brings convenience for the drilling process without any overlap upon the hole position. This method promotes the application of the FBG sensors in the residual stress measurement field.

Using the methods of quantum chemistry and Atom-Atom potentials, the structure of benzotrifuroxan (BTF) cocrystals with nitrobenzenes (nitrobenzene, 1,2-, 1,3-, 1,4-dinitrobenzenes, 1,3,5-trinitrobenzene, hexanitrobenzene) with different ratios components (1:1, 1:2, 1:3 and in reverse order) is modeled. Based on the estimation of the energy of cocrystallization, a prediction was made of the possibility to obtain of cocrystals, some of which were got and investigated by the single-crystal XRD. For the first time, a cocrystal with three BTF molecules and one coformer molecule (1,4-DNB) in a unit cell was obtained. An analysis of the contacts of the crystal packing of studied cocrystals shows that the polarizing effects of oxygen and nitrogen atoms in the BTF ring, which is a π-system with a low electron content, form with nitro groups of coformers, relatively rich in electrons, pseudo-hydrogen bonds and π-π interactions, which leads to the formation of cocrystals. It was experimentally shown that the formation of cocrystals, in addition to the structural features of nitrobenzenes, is also influenced by thermodynamic factors (the polarity of the solvent and the ratio of the components used for cocrystallization).

An unprecedented copper-catalyzed reaction of acetylene analogs with dialkyl azo dicarboxylate and benzazole analogs via a cross-coupling sequence was reported. A library of triazolobenzazole fused ring systems including [1,2,3] triazolo [3,4-b] [1,3] benzothiazole, [1,2,3] triazolo [3,4-b] [1,3] benzoxazole and [1,2,3] triazolo[3,4-b][1,3]benzimidazole structures were obtained in moderate to excellent yields under very mild reaction conditions. Structural confirmation of the final products became possible using different methods like spectroscopy and elemental analysis. The control experiments indicated C-H activation of acetylene by copper salts, followed by cycloaddition between a 2-(phenylethynyl)benzo[d]azol-3(2H)-yl anion and azo dicarboxylate as the key mechanistic feature. The broad substrate scope with simple and easily affordable starting materials, as well as mild reaction conditions are the noticeable attributes of this methodology, which provides facile access to the desired products.

Background and purpose: In this study, some new cytotoxic hybrid structures were synthesized by combining pyrazolinone and imidazolinone rings with quinazoline pharmacophores. Experimental approach: The benzoxazinone, pyrazolo-quinazoline fused ring, and imidazolinone anchored quinazoline derivatives were synthesized by simple ring-opening, ring expansion, and ring closure strategies from oxazolones. The molecular docking studies of the final derivatives were accomplished on the epidermal growth factor receptor enzyme. The cytotoxic effect of the final compounds on the MCF-7 cell line was evaluated by MTT assay. Findings/Results: The docking results confirmed the optimized electrostatic, H-bonding, and hydrophobic interactions of structures with the key residues of the active site (DG bin < -9Kcal/mol). The derivatives have been obtained in good yield and purity, and their structures were confirmed by different methods (FT-IR, 1 H-NMR, 13 C-NMR, and CHNS analysis). The IC50s of all final derivatives against the MCF-7 cell line were lower than 10 μM, and between all, the IXa from pyrazolo-quinazolinone class (IC 50 : 6.43 µM) with chlorine substitute was the most potent. Furthermore, all derivatives showed negligible cytotoxicity on HUVEC normal cell line which would be a great achievement for a novel cytotoxic agent. Conclusion and implications: Based on the obtained results, pyrazolo[1,5-c] quinazolin-2-one series were more cytotoxic than imidazolinone methyl quinazoline-4(3H)-ones against MCF-7 cells. Chlorine substitute in the para position of the aromatic ring improved the cytotoxicity effect in both classes. It could be related to the polarizability of a chlorine atom and making better intermolecular interactions. Further pre-clinical evaluations are required for the promising synthesized cytotoxic compounds.

FMN riboswitch is novel drug targets for the design of new antibiotics and efforts have been employed to design new charged and uncharged ligands. Uncharged ligands have shown advantages of not requiring any transporter for intracellular transport or proteins for their phosphorylation. 5FDQD is recently reported neutral ligand for FMN riboswitch active against the Clostridium difficile infection in mice. However, the crystal structure of 5FDQD bound FMN riboswitch is not available, and the mechanism of ligand binding and triggering the function of riboswitch is not well understood. We have examined the charged FMN and the neutral 5FDQD for their binding affinity with the FMN riboswitch using the well-tempered metadynamics (WT-MtD) simulation technique. The crystal structure of FMN riboswitch shows that the FMN interacts with the J4/5 region through phosphate group with G62, however, 5FDQD takes the advantage of π-π stacking interaction with the same residue of riboswitch observed from the WT-MtD simulation results. The simulation results show that the presence of fluorine on phenyl ring in 5FDQD is important to enhance the binding affinity of the neutral ligands with the FMN riboswitch. The WT-MtD simulation reveals that the 1,2 difluoro substitution on phenyl ring improves the π-π stacking interaction with G62 and enhance the binding free energy (-34.1 kcal/mol) compared to 5FDQD (-33.4 kcal/mol). However, the 1,3 difluoro substitution on the phenyl ring lowered the binding affinity due to the electrostatic repulsion with phosphate group in G62. The electron-donating substitution on phenyl ring such as amino group lowered the binding affinity (-28.8 kcal/mol) with riboswitch than the 5FDQD. The WT-MtD simulation results suggest that the nature of the substituting group and its position on the phenyl ring in neutral ligands are crucial to govern the binding affinity with FMN riboswitch.

An efficient defluorinative net-[3 + 3]-cyclization strategy for the construction of perfluoroalkyl-substituted pyrimidine derivatives by using a series of perfluoroalkyl alkynes and amidines as starting materials was developed. The present reaction proceeded successfully under transition-metal-free conditions to form two new C–N bonds and a new heterocyclic ring through a sequence of hydroamination, defluorination, and annulation. The desired pyrimidines could be obtained with good functional group tolerance and moderate to good yields. Moreover, the distinctive fluorine effects of perfluoroalkyl substituents are vital for tuning the reactivity of alkynes for the anticipated defluorinative annulation. The pendant π system would lower associated bond dissociation energy significantly compared to that of a nonactivated C(sp3)–F bond.

Present paper reports the study of single crystal X-ray diffraction of the compound 4-Amino-N-(3-chloropyrazin-2yl)benzene-1-sulfonamide which crystallizes in an orthorhombic crystal system with the space group Pbca having precise unit cell parameters a = 11.5260(19)A, b = 9.6270(16)A, c = 22.099(5)A, Z = 8 and V = 2452.1(8)A3. The structure was solved by direct methods and was refined by full-matrix least-squares based on F2. After subsequent cycles of refinement, the structure was converges to the Goodness-of-Fit (S) = 1.33. The molecule was adopted as a non-planar structure with a dihedral angle of 89.95°. In the crystal, molecules are held together through intermolecular N–H…O and C–H…O interactions. The nitrogen (N) atom of pyrazine ring has exhibited trifurcated intramolecular relations through C–H…N, N…C, and N…O incorporating S(5), S(6), and S(7) ring motifs, respectively. The intermolecular interactions were analyzed, and their percentage of contribution towards crystal packing was computed using Hirshfeld surface analysis. Also, interaction energies between the different pairs of molecules were analyzed, visualized and estimated using the energy density model of B3LYP/6-31G(d,p).

(±)-Cyclopeltains A and B (1 and 2), two pairs of unusual alkylated adenine derivatives, were isolated from the insect Cyclopelta parva and structurally characterized. 1 and 2 both possess a 6/5/7/5 ring system arising from the alkylation of N7 and N10 by a C6 unit and the formation of a furan ring. A plausible biosynthetic pathway for 1 and 2 was proposed. Biological evaluation of the enantiomers of 1 and 2 revealed that (−)-1 and (+)-2 could inhibit the production of TNF-α and IL-6 and the expression of iNOS, COX-2, and p-NF-κB.

The pyridazine ring in the title compound, C20H17ClN2O3, adopts a screw-boat conformation. The whole molecule is flattened, the dihedral angles subtended by the least-squares plane of the central aromatic ring with those of the terminal benzene and pyridazine rings being 15.18 (19) and 11.23 (19)°, respectively. In the crystal, the molecules are linked by pairs of N—H...O bonds into centrosymmetric dimers and by C—H...π contacts into columns. The results of the Hirshfeld surface analysis show that the most prominent interactions are H...H, accounting for 36.5% of overall crystal packing, and H...O/O...H (18.6% contribution) contacts.

Coumarin-fused-coumarins have attracted significant attention in the scientific world owing to their boundless applications in interdisciplinary areas. Various synthetic pathways have been developed to construct novel coumarin-fused-coumarin analogues by the fusion of modern methodologies with a classical Pechmann reaction or Knoevenagel condensation. Owing to their extended molecular framework, they possess interesting photophysical properties depending on the fused coumarin ring systems. This review highlights previously published reports on the synthetic strategies for structurally diverse coumarin-fused-coumarins. Furthermore, the scope of the synthesized biscoumarin-fused entities is described by highlighting their photophysical properties and applications.

To reduce the cost and firing temperature of traditional ZrO2 insert rings, the new ZrO2-SiCw-C (w-whisker) insert ring materials were successfully synthesized using ZrO2, Si, graphite powders as starting materials, and phenolic resin as binder. The effects of amount of Si powder addition (5, 8 and 11 wt%) and firing temperatures (1100 °C, 1200 °C and 1400 °C) on the phase composition, microstructure and properties of as-obtained products have been investigated. The results show that Si reacts with C or CO at high temperature to form SiCw, which intersperses in the ZrO2 material to develop an interlocking network structure, resulting in strengthening effect and leading to an increase in the strength of the composites. The composites have good oxidation resistance due to the formation of some glass film on the sample surface. The optimum firing temperature is 1200 °C, which is much lower than that of pure ZrO2 material (>1700 °C). The as-prepared ZrO2-SiCw-C materials possess good properties, making good prospects for fabricating insert rings of slide plates.

The random ring-opening terpolymerization of CO2, epoxides, and lactones remains challenging, mainly because CO2/epoxide copolymerization and lactone ring-opening polymerization typically proceed a...

An efficient one-pot four-component reaction for the synthesis of a new family of novel bridgehead nitrogen-containing pyrido[1,2-d][1,4]diazepines has been described and its mechanism has been proposed, which follows a ring-closure and ring-cleavage pathway. The protocol involved a cyclization through γ-selective C-C bond formation, an intramolecular Michael addition and a ring-opening of pyranone ring under refluxing condition with high to excellent yields. The advantages of this methodology, including the use of easily available raw materials and an inexpensive catalyst, an open-air reaction setup, wide functional group tolerance, and Gram-scale synthesis, make the developed methodology a practical way to access novel pyrido[1,2-d][1,4]diazepines and functionalized tricyclic or polycyclic fused 1,4-diazepins as well as novel analogs of important biologically active molecules.

Flowability parameters of powders measured by a shear cell is expected to depend on shear cell size, but details of that effect are lacking. In this work, we have systematically evaluated this using a number of powders under three preshear normal stresses using a ring shear tester. The flowability index (ffc) of a limestone powder (BCR 116) exhibited relatively small differences when measured on three shear cells of different sizes, S (~9.5 cm3) 22 μm was more than 15% higher using S than M. Large differences between data from M and L were found for powders with a median particle size >125 μm. Therefore, one must exercise caution when comparing flow properties of powders characterized using different shear cells.

The synthetic route toward novel tricyclic, nitrogen-containing system is disclosed. Three novel compounds possessing structural features of 1,2,3,4-tetrahydroquinoxaline and decahydropyrido[3,4-b]pyrazine are synthesized starting from readily available precursors in six or seven steps, of which the last three or four steps respectively are diastereoselective. Key reaction steps include N-acylation, Hofmann rearrangement and ring-closing Buchwald– Hartwig reaction. Compounds trans-8, cis-12 and trans-12 are synthesized in order to prove that this novel, tricyclic system can be functionalized with various groups. Synthetic significance of this heterocyclic system lies in the possibility for the orthogonal functionalization of three different amino groups, allowing fine structural tuning. У овом раду представљена је синтеза новог трицикличног система који садржи азот. Три нова једињења код којих су комбиноване структурне карактеристике 1,2,3,4-тетрахидрохиноксалина и декахидропиридо[3,4-b]пиразина, добијена су полазећи од лако доступних прекурсора, у шест или седам фаза од којих су последње три или четири, редом, диастереоселективне. Кључне синтетичке трансформације укључују N-ациловање, Hofmann премештање и интрамолекулску Buchwald–Hartwig реакцију, као фазу у којој долази до циклизације. Једињења trans-8, cis-12 и trans-12 су синтетисана како би се представила могућност функционализације новог трицикличног система. Синтетички значај новог хетероцикличног система представљен је у могућности ортогоналне функционализације три различите амино групе, чиме се може постићи фино подешавање структуре.

A seven-step total synthesis of (+)-cylindricine D and epi-cylindricine D is described. The efficiency relies on the highly diastereoselective reductive bis-functionalization of N,O-protected (S)-pyroglutaminol by our recently improved protocol to build the N-α-tert-alkylamine motif, and a telescoped one-step four-reaction protocol to build the fused bicyclic ring system. (+)-Cylindricine C and its 2-epimer were synthesized by essentially the same sequence in eight steps. Acetylation of the latter then delivered (+)-cylindricine E and its 2-epimer, respectively.