Label-free fluorescence detection of mercury ions based on thymine-mercury-thymine structure and CRISPR-Cas12a.

In this work, we developed a novel label-free fluorescent sensor for the highly sensitive detection of mercury ions (Hg2+) based on the coordination chemistry of thymine-Hg2+-thymine (T-Hg2+-T) structures and the properties of CRISPR-Cas12a systems. Most notably, two T-rich sequences (a blocker and an activator) were designed to form stable double-stranded structures in the presence of Hg2+ via the T-Hg2+-T base pairing. The formation of T-T mismatched double-stranded DNA between the blocker and the activator prevented the cleavage of G-rich sequences by Cas12a, allowing them to fold into G-quadruplex-thioflavin T complexes, resulting in significantly enhanced fluorescence. Under the optimized conditions, the developed sensor showed an excellent response for Hg2+ detection in the linear range of 0.05 to 200 nM with a detection limit of 23 pM. Moreover, this fluorescent sensor exhibited excellent selectivity and was successfully used for the detection of Hg2+ in real samples of Zhujiang river water and tangerine peel, demonstrating its potential in environmental monitoring and food safety applications.

Corrigendum to "The JNU-IFM dataset for segmenting pubic symphysis-fetal head" data in brief. 41 (2022) 107904.

[This corrects the article DOI: 10.1016/j.dib.2022.107904.].

The JNU-IFM dataset for segmenting pubic symphysis-fetal head.

The use of transperineal ultrasound techniques for the assessment of fetal head descent and progression is an adjunct to clinical examination. Automatic identification of parameters based on ultrasound images will greatly reduce the subjectivity and non-repeatability of the clinician's judgment. However, the lack of a pubic symphysis-fetal head dataset hinders the development of algorithms. Here, we present an intrapartum transperineal ultrasound dataset of the Intelligent Fetal Monitoring Lab of Jinan University (named the JNU-IFM dataset), in which intrapartum transperineal ultrasound videos of 78 were recorded from 51 patients. These data were obtained with the Youkey D8 wireless 2D ultrasound probe with its corresponding supporting software by Wuhan Youkey Bio-Medical Electronics Co., Ltd., Wuhan, China. In these videos, 6224 high-quality images with four categories were selected to form the JNU- IFM dataset. These images were labelled using the Pair software and then validated by two experienced radiologists. We hope that this data set can be used in the segmentation of the pubic symphysis-fetal head.

Self-Assembly and Molecular Recognition in Water: Tubular Stacking and Guest-Templated Discrete Assembly of Water-Soluble, Shape-Persistent Macrocycles.

Supramolecular chemistry in aqueous media is an area with great fundamental and practical significance. To examine the role of multiple noncovalent interactions in controlled assembling and binding behavior in water, the self-association of five water-soluble hexakis(m-phenylene ethynylene) (m-PE) macrocycles, along with the molecular recognition behavior of the resultant assemblies, is investigated with UV-vis, fluorescence, CD, and NMR spectroscopy, mass spectrometry, and computational studies. In contrast to their different extents of self-aggregation in organic solvents, all five macrocycles remain aggregated in water at concentrations down to the micromolar (µM) range. CD spectroscopy reveals that 1-F6 and 1-H6, two macrocycles carrying chiral side chains and capable of H-bonded self-association, assemble into tubular stacks. The tubular stacks serve as supramolecular hosts in water, as exemplified by the interaction of macrocycles 1-H6 and 2-H6 and guests G1 through G4, each having a rod-like oligo(p-phenylene ethynylene) (p-PE) segment flanked by two hydrophilic chains. Fluorescence and 1H NMR spectroscopy revealed the formation of kinetically stable, discrete assemblies upon mixing 2-H6 and a guest. The binding stoichiometry, determined with fluorescence, 1H NMR, and ESI-MS, reveals that the discrete assemblies are novel pseudorotaxanes, each containing a pair of identical guest molecules encased by a tubular stack. The two guest molecules define the number of macrocyclic molecules that comprise the host, which curbs the "infinite" stack growth, resulting in a tubular stack with a cylindrical pore tailoring the length of the p-PE segment of the bound guests. Each complex is stabilized by the action of multiple noncovalent forces including aromatic stacking, side-chain H-bonding, and van der Waals interactions. Thus, the interplay of multiple noncovalent forces aligns the molecules of macrocycles 1 and 2 into tubular stacks with cylindrical inner pores that, upon binding rod-like guests, lead to tight, discrete, and well-ordered tubular assemblies that are unprecedented in water.

A combined experimental and theoretical study on the structures, interactions and volumetric properties of guanidinium-based ionic liquid mixtures.

Mixtures of ionic liquids (ILs) have shown their potential in both physical and chemical processes, regarded as alternatives to common ILs. In this work, four guanidinium-based ILs, 2-ethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([TMG(C2)][C2OSO3]) and bis(trifluoromethylsulfonyl)imide ([TMG(C2)][NTf2]), and 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([TMG(C2)2][C2OSO3]) and bis(trifluoromethylsulfonyl)imide ([TMG(C2)2][NTf2]), are employed to investigate the structures, interactions and properties of four systems of IL-IL binary mixtures, including [TMG(C2)][C2OSO3]x[NTf2]1-x, [TMG(C2)]x[TMG(C2)2]1-x[C2OSO3], [TMG(C2)]x[TMG(C2)2]1-x[NTf2] and [TMG(C2)2][NTf2]x[C2OSO3]1-x. Combining experiments with theory, the relationships among H-bond interactions, structures and volumetric properties have been revealed. 1H NMR characterizations show the changes of H-bond interactions in the IL-IL mixtures in relation to composition, and DFT calculations reveal significant cation-anion interactions through the active hydrogen atom (N+-H) and the methyl groups in the cations with the anions in the manner of HO and HF. The ethyl group in the [C2OSO3]- anion hardly forms interactions with other components. The size effect of the calculated system has been evaluated for the IL-IL clusters with 2, 4 and 8 ions. Different structures due to variation of cationic and anionic species have remarkable influence on the volumetric properties of the IL-IL mixtures. Negative excess molar volume (VEm) is found in [TMG(C2)]x[TMG(C2)2]1-x[C2OSO3], and it is caused by the close packing of ions. Positive VEm values indicate that interaction loss occurs in the other three systems, where a linear arrangement or square packing of ions with low space utilization is found.

Antimicrobial activity and cytotoxicity of piperazinium- and guanidinium-based ionic liquids.

Twelve piperazinium- and guanidinium-based ionic liquids (ILs) were synthesized, and characterized by (1)H nuclear magnetic resonance (NMR), thermal gravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The antimicrobial activity and cytotoxicity have been investigated to provide the information whether the newly synthesized ILs are toxic or not. The antimicrobial effects of these ILs on gram negative and gram positive bacteria are evaluated on the basis of the minimum inhibitory concentration (MIC) measurements. The membrane damages of bacteria in the presence of ILs are observed by scanning electron microscopy (SEM). The cytotoxicity data of the ILs on HEK-293 and C6 cells are obtained by MTT cell viability assay. The disruption of cell cycle is analyzed by the flow cytometry. The results show that most of the ILs exhibit low toxicity, and the ILs with tetrafluoroborate anion and with benzene ring on cation are the species with relatively high toxicity among the studied ILs. The fundamental data and results can provide some useful information for the further studies and applications of the ILs.

Formation of Novel Aqueous Two-Phase Systems with Piperazinium-Based Ionic Liquids and Anionic Surfactants: Phase Behavior and Microstructure.

Two novel aqueous two-phase systems (ATPSs) involving protic piperazinium-based ionic liquids (ILs) and anionic surfactants were found in the 1-ethylpiperazinium tetrafluoroborate ([C2pi][BF4]) + sodium dodecyl sulfate (SDS) + H2O system and the 1-phenylpiperazinium tetrafluoroborate ([Phpi][BF4]) + sodium dodecyl benzenesulfonate (SDBS) + H2O system. The ATPS regions in the ternary phase diagrams were determined, and the compositions and the microstructures of the conjugated phases were analyzed by UV-vis, (1)H NMR, DLS, and cryogenic TEM measurements. The results demonstrate size-enhanced micelles for both ATPSs. The strong electrostatic interactions between the cationic moiety of IL and the anionic surfactant play a very important role in the assembly of the large aggregates, and the cation-π interactions are involved in the [Phpi][BF4] + SDBS + H2O ATPS. In addition, the small cationic moiety of [C2pi][BF4] can be packed in the micelles, while the larger hydrophilic cationic moiety of [Phpi][BF4] makes it difficult to get into the micelles, leading to the different size enhancement effects. The driving force of phase separation is the formation and distribution of the large aggregates in the aqueous solutions. This work presents a novel nonaromatic ATPS formed by a piperazinium-based IL and an anionic surfactant, in which considerable size enhancement of aggregates takes place without the assistance of aromaticity in contrast to the other aromatic ATPSs.

Novel Guanidinium-Based Ionic Liquids for Highly Efficient SO2 Capture.

The application of ionic liquids (ILs) for acidic gas absorption has long been an interesting and challenging issue. In this work, the ethyl sulfate ([C2OSO3](-)) anion has been introduced into the structure of guanidinium-based ILs to form two novel low-cost ethyl sulfate ILs, namely 2-ethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([C2(2)(C1)2(C1)2(3)gu][C2OSO3]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium ethyl sulfate ([(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3]). The ethyl sulfate ILs, together with 2-ethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([C2(2)(C1)2(C1)2(3)gu][NTf2]) and 2,2-diethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([(C2)2(2)(C1)2(C1)2(3)gu][NTf2]), are employed to evaluate the SO2 absorption and desorption performance. The recyclable ethyl sulfate ILs demonstrate high absorption capacities of SO2. At a low pressure of 0.1 bar and at 20 °C, 0.71 and 1.08 mol SO2 per mole of IL can be captured by [C2(2)(C1)2(C1)2(3)gu][C2OSO3] and [(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3], respectively. The absorption enthalpy for SO2 absorption with [C2(2)(C1)2(C1)2(3)gu][C2OSO3] and [(C2)2(2)(C1)2(C1)2(3)gu][C2OSO3] are -3.98 and -3.43 kcal mol(-1), respectively. While those by [C2(2)(C1)2(C1)2(3)gu][NTf2] and [(C2)2(2)(C1)2(C1)2(3)gu][NTf2] turn out to be only 0.17 and 0.24 mol SO2 per mole of IL under the same conditions. It can be concluded that the guanidinium ethyl sulfate ILs show good performance for SO2 capture. Quantum chemistry calculations reveal nonbonded weak interactions between the ILs and SO2. The anionic moieties of the ILs play an important role in SO2 capture on the basis of the consistently experimental and computational results.

Observational tools for measuring parent-infant interaction: a systematic review.

The quality of the parent-infant interaction is essential for the infant's development and is most objectively measured by observation. The existing observational tools for assessing parent-infant interaction were identified and described, and their psychometric soundness was evaluated. Twenty electronic databases from inception through June 2013 were searched. Validity was evaluated in five domains (test content, response process, internal structure, relations to other variables, and consequences). Of the 23,961 citations identified, 24 tools were included. Most tools demonstrated a valid rating procedure, reproducibility, and discriminant validity, based on studies with credible quality. The tools lacked factorial and predictive validity, and standardized norms. Further refinement of the existing tools is needed, particularly in the domains of content validity and consequential validity. The synthesized validity evidence and descriptions of the tools reported in this review might guide clinicians and researchers in the selection of an appropriate tool.

Role of the cerebrospinal fluid-contacting nucleus in the descending inhibition of spinal pain transmission.

The brainstem is well recognized as a critical site for integrating descending modulatory systems that both inhibit and facilitate pain at the level of the spinal cord. The cerebrospinal fluid-contacting nucleus (CSF-contacting nucleus) distributes and localizes in the ventral periaqueductal central gray of the brainstem. Although emerging lines of evidence suggest that the CSF-contacting nucleus may be closely linked to transduction and regulation of pain signals, the definitive role of the CSF-contacting nucleus in pain modulation remains poorly understood. In the present study, we determined the role of the CSF-contacting nucleus in rat nocifensive behaviors after persistent pain by targeted ablation of the CSF-contacting nucleus in the brainstem using the cholera toxin subunit B-saporin (CB-SAP), a cytotoxin coupled to cholera toxin subunit B. Compared with CB/SAP, CB-SAP induced complete ablation of the CSF-contacting nucleus, and the CB-SAP-treated rats showed hypersensitivity in responses to acute nociceptive stimulation, and exacerbated spontaneous nocifensive responses induced by formalin, thermal hyperalgesia and mechanical allodynia induced by plantar incision. Furthermore, immunohistochemical experiments showed that the CSF-contacting nucleus was a cluster of 5-HT-containing neurons in the brainstem, and the spinal projection of serotonergic axons originating from the CSF-contacting nucleus constituted the descending 5-HT pathway to the spinal cord. CB-SAP induced significant downregulation of 5-HT in the spinal dorsal horn, and intrathecal injection of 5-HT significantly reversed hypersensitivity in responses to acute nociceptive stimulation in the CB-SAP-treated rats. These results indicate that the CSF-contacting nucleus 5-HT pathway is an important component of the endogenous descending inhibitory system in the control of spinal nociceptive transmission.

Conformational isomerism influence on the properties of piperazinium bis(trifluoromethylsulfonyl)imide.

Investigation of conformational isomerism of ring compounds can help us get a clear comprehension of the ring structure and reveal significant structure-activity relationship. In this study, conformational isomerism of the cationic moiety of ionic liquid 1-ethyl-1,4-dimethylpiperazinium bis(trifluoromethylsulfonyl)imide ([C2C1C1(4)pi][NTf2]) has been investigated by means of (1)H nuclear magnetic resonance spectra. The energy levels for different conformations of the cationic moiety [C2C1C1(4)pi](+) are obtained via density functional theory calculations. The predominant cis-conformer in [C2C1C1(4)pi][NTf2] at its liquid state is observed under ambient conditions, where the ethyl group locates at the equatorial position of quaternary nitrogen atom, consistent with the calculated results. The trans-conformer minorities in the IL convert to the cis-conformers when [C2C1C1(4)pi][NTf2] is well crystallized. Besides, the addition of polar solvents, such as ethanol, leads to a convenient and complete transformation from the trans-form to the recognizable cis-form. The phase-transition behaviors have been measured by means of differential scanning microcalorimetry (DSC), and the DSC results can be highly affected by the initial state of the IL. Density and viscosity measurements for mixtures of [C2C1C1(4)pi][NTf2] with ethanol or 1-propanol at different temperatures T = (293.15 to 323.15) K are performed. Conformational isomerism affects the excess molar volumes of [C2C1C1(4)pi][NTf2] + alcohol systems more significantly than the viscometric property. The behaviors, as comparison, for the mixtures of 1-n-pentyl-1,4-dimethyl-piperazinium bis(trifluoromethylsulfonyl)imide ([C5C1C1(4)pi][NTf2]) with ethanol are observed with the same phenomena as the common binary systems. On the basis of the experimental and calculated results of the ILs, it can be concluded that conformational isomerism in the cation of [C2C1C1(4)pi][NTf2] is quite significant, and it should be taken into account when sensitive properties are evaluated.

A quantum chemistry study on thermochemical properties of high energy-density endothermic hydrocarbon fuel JP-10.

The density functional theory (DFT) calculations at the M06-2X/6-31++G(d,p) level have been performed to explore the molecular structure, electronic structure, C-H bond dissociation enthalpy, and reaction enthalpies for five isodesmic reactions of a high energy-density endothermic hydrocarbon fuel JP-10. On the basis of the calculations, it is found that the carbonium ion C-6 isomer formed from the catalytic cracking at the C6 site of JP-10 has the lowest energy, and the R-5 radical generated from the thermal cracking at the C5 site of JP-10 is the most stable isomer. Furthermore, a series of hypothetical and isodesmic work reactions containing similar bond environments are used to calculate the reaction enthalpies for target compounds. For the same isodesmic reaction, the reaction enthalpy of each carbon site radical has also been calculated. The present work is of fundamental significance and strategic importance to provide some valuable insights into the component design and energy utilization of advanced endothermic fuels.

A DFT study on the thermal cracking of JP-10.

Density functional theory (DFT) calculations have been carried out to investigate the thermal cracking pathways of JP-10, a high energy density hydrocarbon fuel. Thermal cracking mechanisms are proposed, as supported by our previous experimental results (Xing et al. in Ind Eng Chem Res 47:10034-10040, 2008). Using DFT calculations, the potential energy profiles of the possible thermal cracking pathways for all of the diradicals obtained from homolytic C-C bond cleavage of JP-10 were derived and are presented here. The products of the different thermal cracking pathways are in good agreement with our previous experimental observations.

Evaluation of three tracers for labeling distal cerebrospinal fluid-contacting neurons.

It has been reported that distal cerebrospinal fluid-contacting neurons (dCSF-CNs) can be detected by immunohistochemical assay using cholera toxin subunit B-conjugated horseradish peroxidase (CB-HRP). In the present study, another two methods with CB alone or CB-conjugated FITC (CB-FITC) were used, and the results from the three methods were compared. Adult Sprague-Dawley rats were randomly divided into three groups with CB-HRP, CB or CB-FITC. Tracers were diluted to 30% in artificial cerebrospinal fluid and injected separately (in a volume of 3 µL) into the lateral ventricle. Animals from the CB-HRP and CB groups were perfused 48 h after surgery while animals from the CB-FITC group were perfused 1, 3, 6, 12, 24 or 48 h after surgery. The brain was sectioned (40 µm) for immunofluorescence and five sections with positive neurons were selected from each rat for neuron counting. Three clusters of positive neurons in a 'Y-like' distribution were detected ventral to the cerebral aqueduct of rats from the three groups. No significant difference was observed among the quantitative data. In the CB-FITC group, stable staining was detected even at 6 h after injection. Taken together, lateral ventricle injection of CB/CB-FITC is a useful method for labeling dCSF-CNs in rats. The CB-FITC method makes dCSF-CNs labeling much simpler and more convenient.

[Effectiveness evaluation of composite skin grafts in repairing deep burn wounds in functional regions].

OBJECTIVE: To evaluate the long-term effectiveness of composite grafts of acellular dermal matrix (ADM) and autologous split-thickness skin in repairing deep burn wounds. METHODS: Between June 2002 and December 2008, 30 patients (42 wound) were treated. There were 25 males and 5 females, aged 3-52 years with a median age of 31 years. Of them, 24 burned patients had 35 wounds, including 23 deep second degree and 12 third degree wounds with a mean disease duration of 24 days (range, 3-45 days); 6 patients with hyperplastic scar had 7 wounds with a mean disease duration of 16 days (range, 9-21 days). The wound locations were neck (2 wound), hand (4 wounds), forearm and elbow (8 wounds), shoulder (3 wounds), peoples (6 wounds), laps (4 wounds), ankle and legs (15 wounds), and the area of wounds ranged from 10 cm x 10 cm to 30 cm x 20 cm. After thorough debridement, tangential excision, and scar excision, ADM and autologous split-thickness skin graft were used to repair the wounds by one-step method. RESULTS: After operation, composite skin graft survived completely in 39 wounds of 27 patients, with a survival rate of 92.9%; partial necrosis occurred in 3 wounds of 3 patients (7.1%), and healed after dressing change and secondary skin graft. The patients were followed up 30-34 months (mean, 32 months) postoperatively. The appearance of the composite grafts were smooth and soft with good elasticity and low pigmentation. The activity and function of limbs recovered well. No scar hyperplasia was observed at the donor sites. CONCLUSION: It can achieve good outcomes in appearance and function to use ADM and autologous split-thickness skin graft for repairing deep burn wounds in functional regions.

[Observation on the fluid resuscitation and the change in blood sodium of severely burned patients in the early stage].

OBJECTIVE: To study the necessary amount of fluid consisting of electrolyte and colloid, the ratio of electrolyte and colloid used, and the change of blood sodium during early resuscitation in severely burned patients. METHODS: Sixty-seven patients with total burn surface area (TBSA) equal to or over 70% and full-thickness area equal to or over 50%TBSA, hospitalized from March 2004 to March 2009, were resuscitated with fluid. The infusion amount of electrolyte, colloid, and water, and urinary output of patients at post injury hour (PIH) 24, 48, and 72 were analyzed retrospectively. The variation in blood sodium and fluid infusion at different time points was recorded. Data were processed with SPSS 13.0 software. RESULTS: Among the 67 patients, hyponatremia occurred in 9 cases, hypernatremia occurred in 5 cases, and 53 patients had normal blood sodium level. The urinary output of patients within PIH 72 was above 70 mL/h. K value was calculated through the formula: actual total infusion amount of electrolyte and colloid (mL) = burn area (%TBSA) x body weight (kg) x K. In the first 24 PIH, K value was about 1.7, and the ratio of electrolyte and colloid was 1.4. In the second 24 PIH, K value was about 1.3 with electrolyte and colloid ratio 1.6. K value in the third 24 PIH was about 0.9 with electrolyte and colloid ratio 2.0. CONCLUSIONS: The actual amount of resuscitation fluid is slightly larger than that calculated from traditional formula during the early stage in severely burned patients. The amount of electrolytes and the proportion of electrolyte and colloid will influence blood sodium level of patients.

[Influence of vacuum-assisted closure technique on expression of Bcl-2 and NGF/NGFmRNA during wound healing].

OBJECTIVE: To explore the influence of vacuum-assisted closure technique (VAC) on expression of Bcl-2 and NGF during wound healing. METHODS: Eighty Sprague-Dawley rats were randomly divided into 4 groups with 20 rats of each. Group T was the experimental group; group C1, C2 and C3 were the control groups. In group T and group C1, capsaicin was injected subcutaneously to the back of the rats to destroy the sensory nerve. VAC was employed to the wound of the rats in group T and C2 three times a day at 80 mmHg negative pressure. In all the groups, tissue samples were taken from the wound edge and granulation at 1, 3, 6, 9 and 12 days after the injury. Immunohistochemistry and in situ hybridization were used to detect the expression of Bcl-2 and NGF/NGFmRNA in the samples. RESULTS: In group C2 and C3, the expression of Bcl-2 and NGF/NGFmRNA was obvious, which increased gradually and reached the peak at the 9th day. In the process of wound healing, the expression Bcl-2 and NGF/NGFmRNA was higher in the group C2 than in group C3 (P < 0.05). The expression Bcl-2 and NGF/NGFmRNA in group T and C1 was lower than group C2 and C3 (P < 0.05). CONCLUSION: The application of the vacuum-assisted closure technique during wound healing increases the expression of the apoptosic modulation related protein Bcl-2 and affects the expression of NGF/NGFmRNA, which may promote the wound healing process.