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Binary hydrogen bond liquid crystal (HBLC) complex is isolated from the combination of cholesteryl stearate (CHS) and 4-methoxycinnamic acid (4MCA) mesogenic compounds. Induced chiral smectic phases are observed and characterized using a polarizing optical microscope (POM). Enthalpy values and transition temperatures of liquid crystal (LC) phases and their thermal stability are reported using differential scanning calorimetry (DSC), and the same has been supported by the density functional theory (DFT) method. Observation of a strong peak at 3580 cm −1 from the FTIR spectrum confirms the hydrogen bond (H-bond) between chiral (CHS) and non-chiral (4MCA) mesogenic compounds. Further, DFT calculation explores the molecular mechanism of the complexation (CHS + 4MCA). The calculated global reactivity parameters (GRP) values (DFT calculations) justify the stability of the synthesized binary HBLC complex (CHS + 4MCA). In addition, topological analysis of DFT confirms the intermolecular interaction in the title binary HBLC complex. Donor and acceptor interaction in the binary HBLC complex (CHS + 4MCA) is reported using molecular electrostatic potential (MEP) analysis. Further, the impact of increased H-bond length and bond angle on induced chiral smectic ordering has been discussed in the present communication. Quantum theory of atoms-in-molecules (QTAIM) study endorses the existence of linear H-bonding of O–H···O in the binary HBLC complex. In addition, the enhanced mesomorphic behaviour along with non-linear optical properties (NLO) is reported. Graphical Abstract

Abstract The current study describes the presence of Bacillus cereus (B. cereus) in contaminated foods of animal source and ready for human consumption with highlighting on their virulence contributing factors by detection of its virulence genes in addition to identification of their sequencing. Three hundred sixty food samples categorized as (228) meat products and (132) milk products were examined for B. cereus isolation and all of these isolates were confirmed by biochemical tests. Eighteen strains obtained from different food samples were examined for the attendance of a number of virulence genes (nheA, cytK, entFM, bceT and hblC genes) using uniplex PCR method. Furthermore, the B. cereus strains were valued for the sequencing of described genes. Generally 24.44% (88/360) food samples classified as 11.11% (40/360) meat products and 13.33% (48/360) milk products carried B. cereus according to cultural and biochemical properties, with geometric mean (1.5×107±0.15 CFU/g or mL) . The highest counts (above 105 CFU/g or mL) were originated from milk products (with geometric mean 2.2×107±0.22 CFU/g or mL) more than meat products (with geometric mean 1×107±0.19 CFU/g or mL). The results revealed that all of our isolates had one or more virulence (enterotoxin) genes. In our research, the most predominant genes were nheA (100%), followed by cytK (61.11%), entFM (33.33%), bceT (11.11%) then hblC (5.56%). Molecular method detected that overall, 5 strains (27.78%) harbored only 1 gene (nheA), 7 strains (38.88%) harbored 2 genes which classified as 5 strains (27.78%) (nheA and cytK), 2 strains (11.11%) have (nheA and entFM). Moreover, 5 strains (27.78%) have 3 genes classified as 3 strains (16.67%) harbored (nheA, cytK and entFM), 1 strain (5.56%) had (nheA, cytK and hblC), and 1 strain (5.56%) had (nheA, cytK and bceT). Only 1 strain (5.56%) carried 4 tested virulence genes (nheA, cytK, entFM and bceT) genes. The most prevalent gene in meat and dairy foods was nheA (100%). The nucleotide sequences of (bceT, cytK, entFM, hblC and nheA genes) of B. cereus strains were deposited in GenBank under accession no. (MW911824, MW911825, MW911826, MW911827 and MW911828), respectively. Our study was established to indicate the presence of virulent B. cereus in meat and milk products ready for human consumption as a result of deficient hygienic actions. So, a plain for good hygienic measures should be modified to avoid causing serious health problems to human due to ingestion of such products. Resumo O presente estudo descreve a presença de Bacillus cereus em alimentos contaminados de origem animal e prontos para consumo humano, com destaque para seus fatores de contribuição de virulência por meio da detecção de seus genes de virulência, além da identificação de seu sequenciamento. Trezentas e sessenta amostras de alimentos categorizados como produtos cárneos (228) e produtos lácteos (132) foram examinadas para isolamento de B. cereus, e todos esses isolados foram confirmados por testes bioquímicos. Dezoito cepas obtidas de diferentes amostras de alimentos foram examinadas para a presença de uma série de genes de virulência (genes nheA, cytK, entFM, bceT e hblC) usando o método de PCR uniplex. Além disso, as cepas de B. cereus foram avaliadas para o sequenciamento dos genes descritos. De forma geral, 24,44% (88/360) das amostras de alimentos classificados como produtos cárneos (11,11%; 40/360) e produtos lácteos (13,33%; 48/360) transportavam B. cereus, de acordo com as propriedades culturais e bioquímicas, com média geométrica de 1,5 × 10 7 ± 0,15 CFU/g ou mL. Os resultados revelaram que todos os nossos isolados tinham um ou mais genes de virulência (enterotoxina). Em nossa pesquisa, os genes mais predominantes foram nheA (100%), seguidos de cytK (61,11%), entFM (33,33%), bceT (11,11%) e hblC (5,56%). O método molecular detectou que, no geral, 5 cepas (27,78%) apresentavam apenas 1 gene (nheA) e 7 cepas (38,88%) continham 2 genes que foram classificados como 5 cepas (27,78%) (nheA e cytK), 2 cepas (11,11%) possuíam (nheA e entFM). Além disso, 5 cepas (27,78%) continham 3 genes classificados como 3 cepas (16,67%) hospedados (nheA, cytK e entFM), 1 cepa (5,56%) tinha (nheA, cytK e hblC) e 1 cepa (5,56%) teve (nheA, cytK e bceT). Apenas 1 cepa (5,56%) carregava 4 genes de virulência testados (nheA, cytK, entFM e bceT). As sequências de nucleotídeos (genes bceT, cytK, entFM, hblC e nheA) de cepas de B. cereus foram depositadas no GenBank sob o número de acesso (MW911824, MW911825, MW911826, MW911827 e MW911828), respectivamente. Nosso estudo foi estabelecido para indicar a virulência de B. cereus em carnes e produtos lácteos prontos para consumo humano como resultado de ações higiênicas deficientes. Portanto, deve ser estabelecido um plano com boas medidas de higiene para evitar sérios problemas de saúde humana por causa da ingestão de tais produtos.

Hydrogen bonded liquid crystal (HBLC) binary mixture has been synthesized from mesogenic 4-methoxycinnamic acid (4MCA) and mesogenic 4-hexyloxybenzoic acid (6OBA) with different mole ratio. The mesomorphic phase behavior and corresponding phase transition temperatures along with the enthalpy values were investigated by differential scanning calorimetry (DSC). The characteristic textures of 4MCA+6OBA binary mixture were observed by using polarizing optical microscope (POM). Fourier transform infrared spectroscopic (FT-IR) studies confirm the formation of hydrogen bond in the present binary mixture. A note worthy observation in this complex is that pure mesogens have no smectic phase where as 4MCA+6OBA binary mixture exhibits a nematic phase along with higher order smectic C (Sm C) phase. Variation of mole ratio influences thermal properties such as phase peak, enthalpy values and thermal span width of the present HBLC binary mixture complex. The optical tilt angle of 4MCA+6OBA for smectic C phase and thermal stability factors have been investigated. Optical tilt angle for smectic C phase is determined and same is fitted to a power law.

Integrating nanoparticles (NPs) with liquid crystals has emerged as a contemporary research domain in soft matter. The interplay between the two can substantially transform their properties and dynamics. The study conducted the experiments using nanocomposites of hydrogen-bonded supramolecular calamitic liquid crystals doped with ZnO NPs. It is found that the concentration of ZnO and the carbon chain length of the host compounds played a significant role in determining the mesophase transition and crystallization temperatures. The study aimed to investigate the effect of NPs on the electrical properties of liquid crystal nanocomposites, using varying weight percentages (0.5wt%, 2wt%, and 5wt%). Zinc oxide NPs with a particle size of 118 nm is synthesized using a simple starting material. Hydrogen-bonded liquid crystals (HBLCs) viz., P8:FBA and P18:FBA with chain lengths of 8 and 18 carbons, obtained from acid moieties and Schiff bases acted as a host. The nanocomposites exhibited enhanced conductivity with the increase in the dopant concentration while the conductivity decreased as the chain length increased from 8 to 18. It is believed that an increased concentration of NPs increases conductivity through the ion hopping pathway. Adding ZnO NPs to the host HBLC reduces the activation energy and enhances conductivity, making it suitable as functional materials.

Incorporating nanomaterials into liquid crystals has gained popularity since the rise of nanotechnology in the 1990s. The modifications of the physical and chemical properties of liquid crystals are envisioned with the formulation of nanocomposites. In this work, we provide the experimental evidence for the enhancement in the conductivity observed in composites of ZnO nanoparticles (NPs) doped in hydrogen bonded liquid crystals (HBLCs) (P18:FBA) built with (4-pyridyl)-benzylidene-4ʹ-n-octadecylaniline as proton acceptors and 4-Fluorobenzoic acids as proton donors. The FTIR and Photoluminescence studies confirmed the decreased H-bonding interactions proving an efficient pathway for the observed conductivity in the nanocomposites. A theoretical model is proposed for the quantitative explanation of observed conductivity which emphasizes mixed ionic-electronic conductivity.Article HighlightsEnhanced conductivity is achieved with nanocomposites of ZnO NPs with HBLCs.FTIR and Photoluminescence studies confirmed the decreased H-bonding interactions.Application of a recently developed elementary model to analyze the direct current conductivity λDC.Mixed ionic-electronic conductivity is realized.