Hypermethylation of the glutathione peroxidase 4 gene promoter is associated with the occurrence of immune tolerance phase in chronic hepatitis B.

BACKGROUND: Hepatitis B virus (HBV) infection is a public health problem that seriously threatens human health. This study aimed to investigate the clinical significance of glutathione peroxidase 4(GPX4) in the occurrence and development of chronic hepatitis B (CHB). METHODS: A total of 169 participants including 137 patients with CHB and 32 healthy controls (HCs) were recruited. We detected the expression of GPX4 and stimulator of interferon genes (STING) in peripheral blood mononuclear cells (PBMCs) by real-time quantitative polymerase chain reaction (RT-qPCR). The methylation level of GPX4 gene promoter in PBMCs was detected by TaqMan probe-based quantitative methylation-specific PCR (MethyLight). Enzyme-linked immunosorbent assay (ELISA) was performed to detect the serum levels of GPX4, IFN-ß, oxidative stress (OS) related molecules, and pro-inflammatory cytokines. RESULTS: The expression levels of GPX4 in PBMCs and serum of CHB patients were lower than those of HCs, but the methylation levels of GPX4 promoter were higher than those of HCs, especially in patients at the immune tolerance phase. STING mRNA expression levels in PBMCs and serum IFN-ß levels of patients at the immune activation phase and reactivation phase of CHB were higher than those at other clinical phases of CHB and HCs. GPX4 mRNA expression level and methylation level in PBMCs from patients with CHB had a certain correlation with STING and IFN-ß expression levels. In addition, the methylation level of the GPX4 promoter in PBMCs from patients with CHB was correlated with molecules associated with OS and inflammation. CONCLUSIONS: GPX4 may play an important role in the pathogenesis and immune tolerance of CHB, which may provide new ideas for the functional cure of CHB.

Copper and In Situ-Generated Triflic Acid Relay-Promoted Four-Component Cascade Reaction for the Construction of Polysubstituted Cycloguanidines.

An unprecedented copper and in situ-generated triflic acid relay-promoted four-component cascade reaction of cyanamides, diaryliodonium triflates, propargylic amines, and H2O was established for rapid and concise construction of diverse five-membered cycloguanidines. Copper-catalyzed guanidination/intramolecular hydroamination and in situ-generated HOTf-accelerated hydration proceeded sequentially with high level of chemoselectivity and regioselectivity, and six new bonds were simultaneously built in high yields. Thus, diaryliodonium triflates served not only as an arylation reagent but also as an internal acid promoter, establishing an alternative strategy for highly efficient utilization of diaryliodonium trifates.

A novel 68Ga-labeled cyclic peptide molecular probe based on the computer-aided design for noninvasive imaging of PD-L1 expression in tumors.

Programmed death-ligand 1 (PD-L1) serves as a crucial biomarker for guiding the screening of cancer patients and the stratification of immunotherapy. However, due to the high heterogeneity of tumors, the current gold standard for detecting PD-L1 expression (immunohistochemistry) fails to comprehensively evaluate the overall PD-L1 expression levels in the body. Fortunately, the use of PD-L1 targeted radiotracers enables quantitative, real-time, and noninvasive assessment of PD-L1 expression levels and dynamics in tumors. Notably, analyzing the binding mode between the precursor and the target protein to find linker binding sites that do not affect the activity of the target molecule can greatly enhance the successful development of molecular probes. This study introduced a groundbreaking cyclic peptide molecular probe called 68Ga-DOTA-PG1. It was derived from the BMS-71 cyclic peptide and was specifically designed to evaluate the expression of PD-L1 in tumors. The radiolabeling yield of 68Ga-DOTA-PG1 surpassed 97% while maintaining a radiochemical purity of over 99%. In vitro experiments demonstrated the effective targeting of PD-L1 in tumor cells by 68Ga-DOTA-PG1, with significantly higher cellular uptake observed in A375-hPD-L1 cells (PD-L1 + ) compared to A375 cells (PD-L1-). Biodistribution and PET imaging studies consistently showed specific accumulation of 68Ga-DOTA-PG1 in A375-hPD-L1 tumors, with a maximum uptake of 11.06 ± 1.70% ID/g at 2 h, significantly higher than the tumor uptake in A375 cells (1.70 ± 0.17% ID/g). These results strongly indicated that 68Ga-DOTA-PG1 held great promise as a PET radiotracer for imaging PD-L1-positive tumors.

The S1'-S3' Pocket of the SARS-CoV-2 Main Protease Is Critical for Substrate Selectivity and Can Be Targeted with Covalent Inhibitors.

The main protease (Mpro ) of SARS-CoV-2 is a well-characterized target for antiviral drug discovery. To date, most antiviral drug discovery efforts have focused on the S4-S1' pocket of Mpro ; however, it is still unclear whether the S1'-S3' pocket per se can serve as a new site for drug discovery. In this study, the S1'-S3' pocket of Mpro was found to differentially recognize viral peptidyl substrates. For instance, S3' in Mpro strongly favors Phe or Trp, and S1' favors Ala. The peptidyl inhibitor D-4-77, which possesses an α-bromoacetamide warhead, was discovered to be a promising inhibitor of Mpro , with an IC50 of 0.95 µM and an antiviral EC50 of 0.49 µM. The Mpro /inhibitor co-crystal structure confirmed the binding mode of the inhibitor to the S1'-S3' pocket and revealed a covalent mechanism. In addition, D-4-77 functions as an immune protectant and suppresses SARS-CoV-2 Mpro -induced antagonism of the host NF-κB innate immune response. These findings indicate that the S1'-S3' pocket of SARS-CoV-2 Mpro is druggable, and that inhibiting SARS-CoV-2 Mpro can simultaneously protect human innate immunity and inhibit virion assembly.

Sunitinib inhibits RNase L by destabilizing its active dimer conformation.

The pseudokinase (PK) RNase L is a functional ribonuclease and plays important roles in human innate immunity. The ribonuclease activity of RNase L can be regulated by the kinase inhibitor sunitinib. The combined use of oncolytic virus and sunitinib has been shown to exert synergistic effects in anticancer therapy. In this study, we aimed to uncover the mechanism of action through which sunitinib inhibits RNase L. We solved the crystal structures of RNase L in complex with sunitinib and its analogs toceranib and SU11652. Our results showed that sunitinib bound to the ATP-binding pocket of RNase L. Unexpectedly, the αA helix linking the ankyrin repeat-domain and the PK domain affected the binding mode of sunitinib and resulted in an unusual flipped orientation relative to other structures in PDB. Molecular dynamics simulations and dynamic light scattering results support that the binding of sunitinib in the PK domain destabilized the dimer conformation of RNase L and allosterically inhibited its ribonuclease activity. Our study suggested that dimer destabilization could be an effective strategy for the discovery of RNase L inhibitors and that targeting the ATP-binding pocket in the PK domain of RNase L was an efficient approach for modulating its ribonuclease activity.

Review: Radionuclide Molecular Imaging Targeting HER2 in Breast Cancer with a Focus on Molecular Probes into Clinical Trials and Small Peptides.

As the most frequently occurring cancer worldwide, breast cancer (BC) is the leading cause of cancer-related death in women. The overexpression of HER2 (human epidermal growth factor receptor 2) is found in about 15% of BC patients, and it is often associated with a poor prognosis due to the effect on cell proliferation, migration, invasion, and survival. As a result of the heterogeneity of BC, molecular imaging with HER2 probes can non-invasively, in real time, and quantitatively reflect the expression status of HER2 in tumors. This will provide a new approach for patients to choose treatment options and monitor treatment response. Furthermore, radionuclide molecular imaging has the potential of repetitive measurements, and it can help solve the problem of heterogeneous expression and conversion of HER2 status during disease progression or treatment. Different imaging probes of targeting proteins, such as monoclonal antibodies, antibody fragments, nanobodies, and affibodies, are currently in preclinical and clinical development. Moreover, in recent years, HER2-specific peptides have been widely developed for molecular imaging techniques for HER2-positive cancers. This article summarized different types of molecular probes targeting HER2 used in current clinical applications and the developmental trend of some HER2-specific peptides.

Interaction and Kinetics Study of the Co-Gasification of High-solid Anaerobic Digestate and Lignite.

This study aims at investigating the interaction and kinetics behavior of the co-gasification of digestate and lignite. The co-pyrolysis performances of digestate and lignite blended by dry process were better than that blended by wet process, while the wet-blending process could improve the performance in co-gasification stage because of the larger pore diameter and pore volume. When anaerobic digestion (AD) time was 40 days, the synergistic interaction between digestate and lignite were the most remarkable based on the results of thermogravimetric analysis (TG) and the experiments in the lab-scale downdraft fixed bed gasifier. Kinetics study showed that the increase of AD time and the addition of digestate in lignite decreased the activation energy of the co-gasification reaction.

Characterization of Hb Bart's Hydrops Fetalis Caused by - -SEA and a Large Novel α0-Thalassemia Deletion.

Hb Bart's hydrops fetalis is the most severe and generally fatal clinical phenotype of α-thalassemia (α-thal), which is due to the deletion of all four functional α-globin genes of hemoglobin (Hb), resulting in no α-globin chain production (- -/- -). Homozygosity for the - -SEA (Southeast Asian) α-globin gene deletion is the main cause of the Hb Bart's hydrops fetalis in Asia, especially South China. Occasionally, other α0-thal deletions can also be found. In this study, we report a case with an atypical form of Hb Bart's hydrops fetalis that was caused by - -SEA and a large novel α0-thal deletion (- -GX) (Guangxi). The fetus with Hb Bart's in our study presented fetal hydrops features in early gestation which was different from that of traditional Hb Bart's hydrops fetalis with a homozygous - -SEA deletion. The early onset of fetal hydrops is attributed to the decreased formation of embryonic Hb Portland (ζ2γ2), which is proposed as a candidate for reactivation in cases of severe α-thal. Our findings indicated that it was important to characterize new or rare mutations, and highlighted the significance of using ultrasonography to identify signs of Hb Bart's hydrops fetalis.

Computer-Aided Surgical Simulation in Head and Neck Reconstruction: A Cost Comparison among Traditional, In-House, and Commercial Options.

BACKGROUND: Computer-aided surgical simulation (CASS) has redefined surgery, improved precision and reduced the reliance on intraoperative trial-and-error manipulations. CASS is provided by third-party services; however, it may be cost-effective for some hospitals to develop in-house programs. This study provides the first cost analysis comparison among traditional (no CASS), commercial CASS, and in-house CASS for head and neck reconstruction. METHODS: The costs of three-dimensional (3D) pre-operative planning for mandibular and maxillary reconstructions were obtained from an in-house CASS program at our large tertiary care hospital in Northern Virginia, as well as a commercial provider (Synthes, Paoli, PA). A cost comparison was performed among these modalities and extrapolated in-house CASS costs were derived. The calculations were based on estimated CASS use with cost structures similar to our institution and sunk costs were amortized over 10 years. RESULTS: Average operating room time was estimated at 10 hours, with an average of 2 hours saved with CASS. The hourly cost to the hospital for the operating room (including anesthesia and other ancillary costs) was estimated at $4,614/hour. Per case, traditional cases were $46,140, commercial CASS cases were $40,951, and in-house CASS cases were $38,212. Annual in-house CASS costs were $39,590. CONCLUSIONS: CASS reduced operating room time, likely due to improved efficiency and accuracy. Our data demonstrate that hospitals with similar cost structure as ours, performing greater than 27 cases of 3D head and neck reconstructions per year can see a financial benefit from developing an in-house CASS program.

Crystallinity-Modulated Electrocatalytic Activity of a Nickel(II) Borate Thin Layer on Ni3 B for Efficient Water Oxidation.

The exploration of new efficient OER electrocatalysts based on nonprecious metals and the understanding of the relationship between activity and structure of electrocatalysts are important to advance electrochemical water oxidation. Herein, we developed an efficient OER electrocatalyst with nickel boride (Ni3 B) nanoparticles as cores and nickel(II) borate (Ni-Bi ) as shells (Ni-Bi @NB) via a very simple and facile aqueous reaction. This electrocatalyst exhibited a small overpotential of 302 mV at 10 mA cm-2 and Tafel slope of 52 mV dec-1 . More interestingly, it was found that the OER activity of Ni-Bi @NB was closely dependent on the crystallinity of the Ni-Bi shells. The partially crystalline Ni-Bi catalyst exhibited much higher activity than the amorphous or crystalline analogues; this higher activity originated from the enhanced intrinsic activity of the catalytic sites. These findings open up opportunities to explore nickel(II) borates as a new class of efficient nonprecious metal OER electrocatalysts, and to improve the electrocatalyst performance by modulating their crystallinity.

Copper-Catalyzed Domino Three-Component Approach for the Assembly of 2-Aminated Benzimidazoles and Quinazolines.

A copper-promoted three-component synthesis of 2-aminobenzimidazoles (1) or of 2-aminoquinazolines (2) involving cyanamides, arylboronic acids, and amines has been developed. The operationally simple oxidative process, performed in the presence of K2CO3, a catalytic amount of CuCl2·2H2O, 2,2'-bipyridine, and an O2 atmosphere (1 atm), allows the rapid assembly of either benzimidazoles or quinazolines starting from aryl- or benzyl-substituted cyanamides, respectively. In this process, the copper promotes the formation of three bonds, two C-N bonds, and an additional bond resulting from C-H functionalization event.

Chemical Structure Characteristics and Model Construction of Coal with Three Kinds of Coalification Degrees.

The coal structure is extensively used for studying the properties of coal, and the construction of accurate and reliable coal structure models can promote these researches. In this study, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were used to analyze the changes in the coal structure as a function of the coalification degree, and a semiquantitative model construction method based on FTIR, XRD, and X-ray photoelectron spectroscopy (XPS) analyses was proposed. With an increase in the coalification degree, the size of the aromatic cores in the coal increased. During the conversion from lignite to bituminous coal, the content of aliphatic structures increased, while the content of oxygen-containing functional groups (OFGs) significantly decreased. Conversely, during the conversion from bituminous coal to anthracite, the content of aliphatic structures decreased while the content of OFGs slightly increased. The calculated FTIR spectra of the coal structure models were consistent with the experimental FTIR spectra, which confirmed the accuracy of the models. Furthermore, the models successfully explained the microscopic mechanism underlying the differences in the wettability of the coal samples with varying coalification degrees. The construction method and coal structure models in this study will be more widely applied in future research.

Preparation of highly adsorptive biochar by sequential iron impregnation under refluxing and pyrolysis at low temperature for removal of tetracycline.

Iron-doping modification is a prevailing approach for improving adsorption capability of biochar with environmental friendliness, but usually requires high temperature and suffers from iron aggregation. Herein, a highly adsorptive biochar was manufactured via sequential disperse impregnation of iron by refluxing and pyrolysis at low temperature for eliminating tetracycline (TC) from aqueous solution. Iron oxides and hydroxides were impregnated and stably dispersed on the carbon matrix as pyrolyzed at 200 °C, meanwhile abundant oxygen and nitrogen functional groups were generated on surface. The iron-doped biochar exhibited up to 891.37 mg/g adsorption capacity at pH 5, and could be recycled with high adsorption capability. The adsorption of TC should be mostly contributed to the hydrogen bonding of N/O functional groups and the hydrogen bonding/coordination of iron oxides/hydroxides. This would provide a valuable guide for dispersedly doping iron and conserving functional groups on biochar, and a super iron-doped biochar was prepared with superior recyclability.

Polystyrene nanoplastics induce cardiotoxicity by upregulating HIPK2 and activating the P53 and TGF-ß1/Smad3 pathways.

Nanoplastics (NPs) pollution has become a global environmental problem, raising numerous health concerns. However, the cardiotoxicity of NPs exposure and the underlying mechanisms have been understudied to date. To address this issue, we comprehensively evaluated the cardiotoxicity of polystyrene nanoplastics (PS-NPs) in both healthy and pathological states. Briefly, mice were orally exposed to four different concentrations (0 mg/day, 0.1 mg/day, 0.5 mg/day, and 2.5 mg/day) of 100-nm PS-NPs for 6 weeks to assess their cardiotoxicity in a healthy state. Considering that individuals with underlying health conditions are more vulnerable to the adverse effects of pollution, we further investigated the cardiotoxic effects of PS-NPs on pathological states induced by isoprenaline. Results showed that PS-NPs induced cardiomyocyte apoptosis, cardiac fibrosis, and myocardial dysfunction in healthy mice and exacerbated cardiac remodeling in pathological states. RNA sequencing revealed that PS-NPs significantly upregulated homeodomain interacting protein kinase 2 (HIPK2) in the heart and activated the P53 and TGF-beta signaling pathways. Pharmacological inhibition of HIPK2 reduced P53 phosphorylation and inhibited the activation of the TGF-ß1/Smad3 pathway, which in turn decreased PS-NPs-induced cardiotoxicity. This study elucidated the potential mechanisms underlying PS-NPs-induced cardiotoxicity and underscored the importance of evaluating nanoplastics safety, particularly for individuals with pre-existing heart conditions.

Biomechanical Evaluation of Fourth Generation Minimally Invasive Distal First Metatarsal Osteotomy-Akin Osteotomy Technique on First Ray Articular Contact Properties.

BACKGROUND: Hallux valgus is a common deformity encountered but remains a complex clinical entity. Fourth-generation minimally invasive surgery (MIS) techniques consisting of a percutaneous distal metatarsal transverse osteotomy combined with an Akin osteotomy have been used to address mild to severe hallux valgus deformities. The benefits of an MIS approach include improved cosmesis, faster recovery, lower opiate requirement, immediate weightbearing, and favorable outcomes relative to a traditional, open procedure. An understudied area with respect to hallux valgus correction is the effect that osteotomies can have on the articular contact properties of the first ray following correction. METHODS: Sixteen paired cadaveric specimens were dissected to include the first ray and tested in a customized apparatus. Specimens were randomized to receive a distal transverse osteotomy translated either 50% or 100% of the width of the first metatarsal shaft. The osteotomy was performed with either a 0° or 20° distal angulation of the burr relative to the shaft in the axial plane. Specimens were tested in the intact state and following the distal first metatarsal osteotomy for peak pressure, contact area, contact force and center of pressure at the first metatarsophalangeal (MTP) and first tarsometatarsal (TMT) joints. An Akin osteotomy was then performed on each specimen, and peak pressure, contact area, contact force, and center of pressure were recalculated. RESULTS: There was a notable decrease in peak pressure, contact area, and contact force across the TMT joint with greater shifts of the capital fragment. However, at 100% translation of the capital fragment, distal angulation of the osteotomy by 20° appears to improve loading across the TMT joint. Addition of the Akin osteotomy at 100% translation also aids in increasing the contact force across the TMT joint. The MTP joint is less sensitive to changes in shifts and angulation of the capital fragment. The Akin osteotomy also leads to increased contact force across the MTP joint when the capital fragment is translated 100%. CONCLUSION: While the clinical significance is unknown, larger shifts of the capital fragment lead to greater load alterations at the level of the TMT joint than the MTP joint. Distal angulation of the capital fragment and the addition of an Akin osteotomy can aid in reducing the size of those changes. The Akin can lead to increased contact forces at the MTP joint with 100% translation of the capital fragment. LEVEL OF EVIDENCE: Not applicable, Biomechanical study.

An iron(III) complex-based supramolecular organic framework (SOF) as a theranostic platform via magnetic resonance imaging-guided chemotherapy.

It is crucially important to explore the additional metal-endowed functions of supramolecular organic frameworks (SOFs) for expanding their applications. In this work we have reported the performance of a SOF (designated as Fe(III)-SOF) as a theranostic platform via magnetic resonance imaging (MRI)-guided chemotherapy. The Fe(III)-SOF may be used as an MRI contrast agent for cancer diagnosis because the building unit (iron complex) contains high spin iron(III) ions. Additionally, the Fe(III)-SOF may also be used as a drug carrier because it possesses stable internal voids. We loaded doxorubicin (DOX) into the Fe(III)-SOF to obtain a DOX@Fe(III)-SOF. The Fe(III)-SOF showed good loading content (16.3%) and high loading efficiency (65.2%) for DOX. Additionally, the DOX@Fe(III)-SOF had a relatively modest relaxivity value (r2 = 19.745 mM-1 s-1) and exhibited the strongest negative contrast (darkest) at 12 h of post-injection. Furthermore, the DOX@Fe(III)-SOF effectively inhibited tumor growth and showed high anticancer efficiency. In addition, the Fe(III)-SOF was biocompatible and biosafe. Therefore, the Fe(III)-SOF was an excellent theranostic platform and may have potential applications in tumor diagnosis and treatment in the future. We believe that this work will initiate extensive research endeavors not only on the development of SOFs, but also on the construction of theranostic platforms based on SOFs.

Oxidative magnetization of biochar at relatively low pyrolysis temperature for efficient removal of different types of pollutants.

A novel oxidative magnetization, involving phosphomolybdic acid and Fe(NO3)3 co-promoted pyrolysis, was established to manufacture highly adsorptive magnetic biochars for adsorbing aqueous tetracycline, methylene blue, and Cr6+. The modification of phosphomolybdic acid greatly boosted the formation of γ-Fe2O3 and oxygen containing groups with enhancement of specific surface area and pore volume at 400 °C. Importantly, γ-Fe2O3 was stably fixed on surface in quasi-nanoscale. The oxidized magnetic biochar displayed 631.53, 158.45, 155.13 mg/g adsorption capabilities for tetracycline, methylene blue, and Cr6+ with 22.79 emu/g saturation magnetization, respectively. Oxygen containing groups and quasi-nanoscale γ-Fe2O3 served as key adsorption sites for these pollutants. A general oxidative magnetization was established for manufacturing high-performance magnetic biochar through phosphomolybdic acid/Fe(NO3)3 co-promoted pyrolysis at relatively low temperature.

Predicting skip metastasis in lateral lymph nodes of papillary thyroid carcinoma based on clinical and ultrasound features.

Background: Skip metastasis in papillary thyroid cancer (PTC), defined as lateral lymph node metastasis (LLNM) without the involvement of central lymph node metastasis (CLNM), is generally unpredictable. Our study aimed to develop a model to predict skip metastasis by using clinicopathological and ultrasound factors of PTC. Methods: We retrospectively reviewed the medical records of patients who underwent total thyroidectomy and central lymph node dissection (CLND) plus lateral lymph node dissection (LLND) between January 2019 and December 2021 at the First Affiliated Hospital of Soochow University. Furthermore, univariate and multivariate analyses assessed the clinical and ultrasound risk factors. Receiver operating characteristic (ROC) curves were used to find the optimal cut-off values for age and dominant nodule diameter. Multivariate logistic regression analysis results were used to construct a nomogram and were validated internally. Results: In all patients, the skip metastasis rate was 15.4% (41/267). Skip metastasis was more frequently found in patients with a tumour size ≤10 mm (OR 0.439; P = 0.033), upper tumour location (OR 3.050; P=0.006) and fewer CLNDs (OR 0.870; P = 0.005). After analysing the clinical and ultrasound characteristics of the tumour, five factors were ultimately associated with lateral lymph node skip metastasis and were used to construct the model. These factors were an age >40 years, tumour diameter <9.1 mm, upper tumour location, non-smooth margin and extrathyroidal extension. The internally evaluated calibration curves indicated an excellent correlation between the projected and actual skip metastasis probability. The nomogram performed well in discrimination, with a concordance index of 0.797 (95% CI, 0.726 to 0.867). Conclusions: This study screened for predictors of skip metastasis in PTC and established a nomogram that effectively predicted the risk of potential skip metastasis in patients preoperatively. The method can predict and distinguish skip metastases in PTC in a simple and inexpensive manner, and it may have future therapeutic utility.

Tuning Stiffness with Granular Chain Structures for Versatile Soft Robots.

Stiffness variation can greatly enhance soft robots' load capacity and compliance. Jamming methods are widely used where stiffness variation is realized by jamming of particles, layers, or fibers. It is still challenging to make the variable stiffness components lightweight and adaptive. Besides, the existing jamming mechanisms generally encounter deformation-induced softening, restricting their applications in cases where large deformation and high stiffness are both needed. Herein, a multifunctional granular chain assemblage is proposed, where particles are formed into chains with threads. The chain jamming can be classified into two types. Granular chain jamming (GCJ) utilizes typical particles such as spherical particles, which can achieve both high stiffness and great adaptability while keeping jamming components relatively lightweight, while by using cubic particles, a peculiar deformation-induced stiffening mechanism is found, which is termed as stretch-enhanced particle jamming (SPJ). The versatility of GCJ and SPJ mechanisms in soft robots is demonstrated through soft grippers, soft crawlers, or soft bending actuators, where great passive adaptability, high load capacity, joint-like bending, friction enhancement, or postponing buckling can be realized, respectively. This work thus offers a facile and low-cost strategy to fabricate versatile soft robots.

New Insight into Temperature Effects on Low-Rank Coal Flotation Using Diesel as a Collector.

Efficient flotation of low-rank coal is of great significance for the development of green and low-carbon cycles. Temperature is a crucial parameter of flotation, but the mechanism of its effect on flotation lacks understanding. In this paper, the mechanism was studied by kinetic flotation, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, low-temperature liquid-nitrogen adsorption (LP-N2A), X-ray photoelectron spectroscopy (XPS), and molecular dynamics simulation. The flotation combustible recovery gradually decreases as temperature rises. Compared with 60 °C, the combustible recovery at 5 °C increases by 18.13%. The desorption energy for oil droplets decreases as the temperature rises. As a result, the oil droplets are easier to desorb at high temperatures. The SEM and LP-N2A results demonstrate that the pores and fractures of the coal sample are well developed. Also, the oil-water interfacial tension and viscosity of oil droplets decrease as the temperature rises, while the diffusion ability increases. These increase the volume of oil droplets that penetrate into the pores, resulting in poor spreadability of oil droplets on the coal surface. The average volume of bubbles gradually increases as temperature rises, which renders the flotation foam unstable and worsens the flotation. Therefore, the flotation performance is better at low temperatures.