THz enantiomers of drugs recognized by the polarization enhancement of gold nanoparticles on an asymmetric metasurface.

Chirality plays an important role in biological processes, and enantiomers often possess similar physical properties and different physiological functions. Thus, chiral detection of enantiomers has become a hot topic in recent years, and methods to enhance chiral molecular recognition are in urgent demand. In this work, a polarization detection method was used for different chiral drugs based on a specially designed metasurface composed of asymmetric double-opened rings and the surface enhancement effect of gold nanoparticles (GNPs). The experiment results show that the frequency shifts caused by the nearfield interaction of the metasurface and biomolecules have been significantly improved by GNPs, and both the limit of detection and detection precision of the metasurface can reach the 10-5 g ml-1 level. Moreover, the polarization sensing characterized by right circular polarization (RCP), the polarization elliptical angle (PEA), and the polarization rotation angle (PRA) shows that the enantiomers of three drugs can be distinguished, especially using the PEA spectrum; the maximum difference between enantiomers is over 30° with a precision of 6.6 × 10-7 g mL-1. Our THz polarization sensing and the GNP enhancement method inspire an efficient strategy for the highly sensitive detection of enantiomers.

Terahertz phase shift sensing and identification of a chiral amino acid based on a protein-modified metasurface through the isoelectric point and peptide bonding.

The efficient sensing of amino acids, especially the distinction of their chiral enantiomers, is important for biological, chemical, and pharmaceutical research. In this work, a THz phase shift sensing method was performed for amino acid detection based on a polarization-dependent electromagnetically induced transparency (EIT) metasurface. More importantly, a method for binding the specific amino acids to the functional proteins modified on the metasurface was developed based on the isoelectric point theory so that the specific recognition for Arginine (Arg) was achieved among the four different amino acids. The results show that via high-Q phase shift, the detection precision for L-Arg is 2.5 × 10-5 g /ml, much higher than traditional sensing parameters. Due to the specific electrostatic adsorption by the functionalized metasurface to L-Arg, its detection sensitivity and precision are 22 times higher than the other amino acids. Furthermore, by comparing nonfunctionalized and functionalized metasurfaces, the D- and L-chiral enantiomers of Arg were distinguished due to their different binding abilities to the functionalized metasurface. Therefore, this EIT metasurface sensor and its specific binding method improve both detection precision and specificity in THz sensing for amino acids, and it will promote the development of THz highly sensitive detection of chiral enantiomers.

Pollutant removal from municipal sewage by a microaerobic up-flow oxidation ditch coupled with micro-electrolysis.

The development of efficient and low-cost wastewater treatment processes remains an important challenge. A microaerobic up-flow oxidation ditch (UOD) with micro-electrolysis by waterfall aeration was designed for treating real municipal wastewater. The effects of influential factors such as up-flow rate, waterfall height, reflux ratio, number of stages and iron dosing on pollutant removal were fully investigated, and the optimum conditions were obtained. The elimination efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4 +-N), total nitrogen (TN) and total phosphorus (TP) reached up to 84.33 ± 2.48%, 99.91 ± 0.09%, 93.63 ± 0.60% and 89.27 ± 1.40%, respectively, while the effluent concentrations of COD, NH4 +-N, TN and TP were 20.67 ± 2.85, 0.02 ± 0.02, 1.39 ± 0.09 and 0.27 ± 0.02 mg l-1, respectively. Phosphorous removal was achieved by iron-carbon micro-electrolysis to form an insoluble ferric phosphate precipitate. The microbial community structure indicated that carbon and nitrogen were removed via multiple mechanisms, possibly including nitrification, partial nitrification, denitrification and anammox in the UOD.

Needle Adjustment Free (NAF) running suture technique (PAN suture) in laparoscopic partial nephrectomy.

BACKGROUND: It is proposed a new running suture technique called Needle Adjustment Free (NAF) technique, or PAN suture. The efficiency and the safety were evaluated in laparoscopic partial nephrectomy. METHODS: This new running suture technique avoids the Needle Adjustment method used in traditional techniques. The new continuous suture technique (11 patients) was compared with the traditional continuous suture method (33 patients) used in both transperitoneal and retroperitoneal laparoscopic partial nephrectomy (LPN) in terms of suture time (ST), warm ischemia time (WIT), blood loss (BL), open conversion rate and post-op discharge time, post-op bleeding, post-op DVT, ΔGFR (affected side, 3 months post-op). Differences were considered significant when P < 0.05. RESULTS: ST in the PAN suture group was 30.37 ± 16.39 min, which was significant shorter (P = 0.0011) than in the traditional technique group which was 13.68 ± 3.33 min. WIT in the traditional technique group was 28.73 ± 7.89 min, while in the PAN suture group was 20.64 ± 5.04 min, P = 0.0028. The BL in entirety in the traditional technique group was 141.56 ± 155.23 mL, and in the PAN suture group was 43.18 ± 31.17 mL (P = 0.0017). BL in patients without massive bleeding in the traditional technique group was significantly greater than in the PAN suture group at 101.03 ± 68.73 mL versus 43.18 ± 31.17 mL (P = 0.0008). The open conversion rate was 0 % in both groups. There was no significant difference between the two groups in postoperative discharge time, post-op bleeding, post-op DVT, ΔGFR (affected side, 3 months post-op). CONCLUSIONS: The NAF running suture technique, or PAN suture, leading to less ST, WIT and BL, which was shown to be more effective and safer than the traditional technique used for LPN. A further expanded research with larger sample size is needed.

Wideband sub-THz half-wave plate using 3D-printed low-index metagratings with superwavelength lattice.

High-index dielectric metasurfaces are rarely reported around 0.1-0.3 THz, as an extremely large etching depth is needed according to the millimeter-scale wavelength. In this work, we propose an easy solution to sub-THz wideband polarization control by utilizing 3D-printed low-index (n~1.5) metagratings. The metagrating with subwavelength lattice is shown as a very efficient half-wave plate (net polarization conversion of 87%) at 0.14 THz but showing noisy spectrum. The design with superwavelength lattice offers a smooth and wide bandwidth for linear polarization rotation. Study of the mechanism shows that the lattice size slightly above wavelength is a better choice for the low-index metadevice as it maintains high efficiency in the zero diffraction order and wide bandwidth due to the small mode dispersion. Such designs offer a feasible solution especially suitable for sub-THz polarization and phase control, complementary to the existing high-index dielectric and metallic metasurfaces.

Population Pharmacokinetics and Bayesian Estimation of Mycophenolic Acid Exposure in Chinese Renal Allograft Recipients After Administration of EC-MPS.

The aim of the present study is to establish a population pharmacokinetic (PPK) model of mycophenolic acid (MPA) and limited sampling strategy models for the estimation of MPA exposure in Chinese adult renal allograft recipients following oral administration of enteric coated mycophenolate sodium (EC-MPS). A total of 74 sets of full pharmacokinetic profiles and 47 sets of MPA-sparing samples were collected from 102 renal transplant recipients who received oral EC-MPS. The MPA concentration was determined by an enzyme-multiplied immunoassay technique, and the pathophysiologic data were recorded. The PPK model was constructed using nonlinear mixed-effects modeling, and the limited sampling strategy models for MPA were established by using multiple regression analysis and the maximum a posteriori Bayesian assay based on 2 to 4 sampling time points following EC-MPS administration. The pharmacokinetics of MPA were best described by a 2-compartment model with a first-order absorption process and a lag time of absorption. The clearance of MPA was 12.3 ± 1.14 L/h. Comedicating with cyclosporine A was found to have a significant impact on the clearance/bioavailability of MPA (P < .01). Sampling strategies consisted of plasma concentration at 1.5, 2, 4 (C1.5-C2-C4) hours and 1.5, 2, 4, 6 (C1.5-C2-C4-C6) hours after EC-MPS administration were shown to be suitable for the estimation of the MPA area under the concentration-time curve in these patients. The PPK model was acceptable and can describe the pharmacokinetics of MPA in Chinese renal transplant recipients administered EC-MPS. The area under the concentration-time curve of MPA in Chinese renal transplant recipients could be estimated through a limited sampling strategy method, based on which individualized immunosuppressive regimens could be designed.

Broadband controllable terahertz quarter-wave plate based on graphene gratings with liquid crystals.

Developing the broadband controllable or tunable terahertz (THz) polarization and phase devices are in an urgent need. In this paper, we demonstrate a broadband controllable THz quarter-wave plate (QWP) with double layers of graphene grating and a layer of liquid crystals. The double layer graphene gratings can achieve a switchable QWP to switch between linear-to-linear and linear-to-circular polarization states with over 0.35THz bandwidth in the ON or OFF state by applying biased electric field on the graphene grating or not. Moreover, this QWP based on the structure of periodic gradient grating can significantly enhance the phase difference between two orthogonally polarized components compared to that based on equal-periodic grating structure because of the additional phase distribution of the gradient structures. Furthermore, we incorporate liquid crystals into the graphene grating to form a tunable QWP, of which operating frequency can be continuously tuned in a wide frequency range by electrically controlling the molecular director of the liquid crystals. The results show that the graphene periodic gradient grating with LCs not only broadens the operating bandwidth, but also reduces the external electric field. This device offers a further step in the development of THz polarization and phase devices for potential applications in THz polarized imaging, spectroscopy, and communication.

Tunable terahertz wave-plate based on dual-frequency liquid crystal controlled by alternating electric field.

In this work, the optically anisotropic property of dual-frequency liquid crystals (DFLC) in terahertz (THz) regime has been experimentally investigated, which indicates that the refractive index and birefringence of DFLC can be continuously modulated by both the alternating frequency and intensity of the alternating electric field. This tunability originates from the rotation of DFLC molecules induced by alternating electric fields. The results show that by modulating the alternating frequency from 1 kHz to 100 kHz under 30 kV/m electric field, the 600 µm thickness DFLC cell can play as a tunable quarter-wave plate above 0.68 THz, or a half-wave plate above 1.33 THz. Besides, it can be viewed as a tunable THz phase shifter from 0 to π. Therefore, due to its novel tuning mechanism, DFLC will be of great significance in dynamic manipulating on THz phase and polarization.

Population pharmacokinetics and Bayesian estimation of mycophenolic acid concentrations in Chinese adult renal transplant recipients.

Mycophenolate mofetil (MMF) is an important immunosuppressant used in renal transplantation, and mycophenolic acid (MPA) is the active component released from the ester prodrug MMF. The objective of this study was to investigate the population pharmacokinetics of mycophenolic acid (MPA) following oral administration of MMF in Chinese adult renal transplant recipients and to identify factors that explain MPA pharmacokinetic variability. Pharmacokinetic data for MPA and covariate information were retrospectively collected from 118 patients (79 patients were assigned to the group for building the population pharmacokinetic model, while 39 patients were assigned to the validation group). Population pharmacokinetic data analysis was performed using the NONMEM software. The pharmacokinetics of MPA was best described by a two-compartment model with a first-order absorption rate with no lag time. Body weight and serum creatinine level were positively correlated with apparent clearance (CL/F). The polymorphism in uridine diphosphate glucuronosyltransferase gene, UGT2B7, significantly explained the interindividual variability in the initial volume of distribution (V1/F). The estimated population parameters (and interindividual variability) were CL/F 18.3 L/h (34.2%) and V1/F 27.9 L (21.3%). The interoccasion variability was 13.7%. These population pharmacokinetic data have significant clinical value for the individualization of MMF therapy in Chinese adult renal transplant patients.

Terahertz polarization converter and one-way transmission based on double-layer magneto-plasmonics of magnetized InSb.

In this work, we investigate the nonreciprocal circular dichroism for terahertz (THz) waves in magnetized InSb by the theoretical calculation and numerical simulation, which indicates that longitudinally magnetized InSb can be applied to the circular polarizer and nonreciprocal one-way transmission for the circular polarization THz waves. Furthermore, we propose a double-layer magnetoplasmonics based on the longitudinally magnetized InSb, and find two MO enhancement mechanisms in this device: the magneto surface plasmon resonance on the InSb-metal surface and Fabry-Pérot resonances between two orthogonal metallic gratings. These two resonance mechanisms enlarge the MO polarization rotation and greatly reduce the external magnetic field below 0.1T. The one-way transmission and perfect linear polarization conversion can be realized over 70dB, of which the transmittance can be modulated from 0 to 80% when the weak magnetic field changes from 0 to 0.1T under the low temperature around 200K. This magnetoplasmonic device has broad potential as a THz isolator, modulator, polarization convertor, and filter in the THz application systems.

Cytotoxicity of AgNPs/CS composite films: AgNPs immobilized in chitosan matrix contributes a higher inhibition rate to cell proliferation.

In this study, the cytotoxicity of sliver nanoparticle-doped chitosan composite films (AgNPs/CS) was investigated in vitro. In this slow-release system, the doped silver nanoparticles (AgNPs) might modify both the surface properties of the matrix and the ion environment of the surrounding fluid via slow-release, determining the dominant mechanism is of interest. Here, AgNPs (average size is 25 nm) were doped into chitosan (CS) films by mechanical mixing to form a slow-release system. The surface properties and stabilities of the films and the Ag-releasing behavior were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectrophotometry, and a weight loss method. The morphology of adhered cells and the survival rate (obtained by both MTT and CCK-8 assays) of human umbilical vein endothelial cells (HUVEC) were employed to describe the cytotoxicity. Using statistical analysis, the following conclusions can be made: the doped AgNPs dispersed in the CS matrix with a polycrystalline structure. During the early erosion, a small amount of debris peeled off and became suspended in the fluid. After that erosion, the composite film became relatively stable, and the doped Ag was slowly released into the fluid. In comparison with the released Ag (either in the peeled debris or dissolved in the fluid), Ag immobilized in the AgNPs/CS films shows a more significant influence on cell adhesion and subsequent proliferation. Film thickness and AgNP content show a synergistic effect on the survival rate of the cell, with the AgNPs content being the key factor.

[Effect of 33 Hz Pulsed Electric Field on Insulin Amyloidosis].

The destabilizing of protein leads to self-aggregation and fibrillar assemblies. In the form of amyloid fibrils or fibril precursors, protein not only lacks the original biological function but also may be harmful to organisms. Stimulated by an intense electric field, the secondary structures of protein can be disturbed and transfer to aggregations or unfolding conformations, which may inhibit the fibrillation process. As a model for disease-associated amyloids, insulin fibrillation is proposed to occur via partial unfolding of a monomeric intermediate. This project is focusing on in-vitro studies employing a 33 Hz pulsed electric field (PEF) to see if there is possible causal connection between insulin fibrillation and PEF exposure. Thioflavin T (ThT)-fluorescence, circular dichroism(CD) and transmission electron microscopy (TEM) techniques were employed regarding the effects of exposure duration and field intensity of the PEF on the fibrillation mechanism of insulin. The results confirm that the PEF exposed insulin molecules may primitively have a slight change in its native structure, causing aggregation. The aggregates in the PEF exposed insulin solution are difficult to dissolve to facilitate the unfolding of insulin molecules. When the molecular conformation converts from α-helical to ß-sheet structure, the fibrillation velocity in the PEF exposed insulin is accelerated by the PEF exposure thereby shortening the lifetime of the intermediates. The morphology of mature fibrils changes from long twisted fibrils to shorter and less matured fibrils. All these effects enhance when the exposure duration and electric intensity increase. The investigated evidences suggest that the PEF can inhibit insulin amyloidosis.

Analysis of cancer incidence in Zhejiang cancer registry in China during 2000 to 2009.

OBJECTIVE: The Zhejiang Provincial Cancer Prevention and Control Office collected cancer registration data during 2000 to 2009 from 6 cancer registries in Zhejiang province of China in order to analyze the cancer incidence. METHODS: Descriptive analysis included cancer incidence stratified by sex, age and cancer site group. The proportions and cumulative rates of 10 common cancers in different groups were also calculated. Chinese population census in 1982 and Segi's population were used for calculating age-standardized incidence rates. The log-linear model was used for fitting to calculate the incidence trends. RESULTS: The 6 cancer registries in Zhejiang province in China covered a total of 60,087,888 person-years during 2000 to 2009 (males 30,445,904, females 29,641,984). The total number of new cancer cases were 163,104 (males 92,982, females 70,122). The morphology verified cases accounted for 69.7%, and the new cases verified only by information from death certification accounted for 1.23%. The crude incidence rate in Zhejiang cancer registration areas was 271.5/105 during 2000 to 2009 (male 305.41/105, female 236.58/105), age-standardized incidence rates by Chinese standard population (ASIRC) and by world standard population (ASIRW) were 147.1/105 and 188.2/105, the cumulative incidence rate (aged from 0 to 74) being 21.7%. The crude incidence rate was 209.6/105 in 2000, and it increased to 320.20/105 in 2009 (52.8%), with an annual percent change (APC) of 4.51% (95% confidence interval, 3.25%-5.79%). Age-specific incidence rate of 80-84 age group was achieved at the highest point of the incidence curve. Overall with different age groups, the cancer incidences differed, the incidence of liver cancer being highest in 15-44 age group in males; the incidence of breast cancer was the highest in 15-64 age group in females; the incidences of lung cancer were the highest in both males and females over the age of 65 years. CONCLUSIONS: Lung cancer, digestive system malignancies and breast cancer are the most common cancers in Zhejiang province in China requiring an especial focus. The incidences of thyroid cancer, prostate cancer, cervical cancer and lymphoma have increased rapidly. Prevention and control measures should be implemented for these cancers.

Weak power frequency magnetic field acting similarly to EGF stimulation, induces acute activations of the EGFR sensitive actin cytoskeleton motility in human amniotic cells.

In this article, we have examined the motility-related effects of weak power frequency magnetic fields (MFs) on the epidermal growth factor receptor (EGFR)-sensitive motility mechanism, including the F-actin cytoskeleton, growth of invasive protrusions and the levels of signal molecules in human amniotic epithelial (FL) cells. Without extracellular EGF stimulation, the field stimulated a large growth of new protrusions, especially filopodia and lamellipodia, an increased population of vinculin-associated focal adhesions. And, an obvious reduction of stress fiber content in cell centers was found, corresponding to larger cell surface areas and decreased efficiency of actin assembly of FL cells in vitro, which was associated with a decrease in overall F-actin content and special distributions. These effects were also associated with changes in protein content or distribution patterns of the EGFR downstream motility-related signaling molecules. All of these effects are similar to those following epidermal growth factor (EGF) stimulation of the cells and are time dependent. These results suggest that power frequency MF exposure acutely affects the migration/motility-related actin cytoskeleton reorganization that is regulated by the EGFR-cytoskeleton signaling pathway. Therefore, upon the MF exposure, cells are likely altered to be ready to transfer into a state of migration in response to the stimuli.

[Incidence and mortality of cancer in Zhejiang province in 2009].

OBJECTIVE: To investigate the incidence and mortality of cancer registered in Zhejiang province in 2009. METHODS: The statistics of incidence and mortality of cancer were collected from 6 population-based cancer registries in Zhejiang province, including 30 613 new incidence cases and 16 920 death cases reported in 2009. The 6 cancer registries covered population at 9 560 699 in all. The crude rate, age-standardized rate, cumulative rate (0-74 years old), cut rate (35-64 years old), age-specific rate of incidence/mortality as well as the constitution of top 10 common cancers were then calculated and analyzed. The age-standardized rate was calculated and adjusted by the Chinese standard population in 1982 as well as the Segi's world standard population. RESULTS: The crude incidence of cancer was 320.20/100 000. Age-standardized incidence by Chinese standard population and by world standard population were separately 161.99/100 000 and 207.92/100 000, the cumulative rate was 23.83% and the cut rate was 346.87/100 000. Meanwhile, the crude mortality rate was 176.97/100 000, and the age-standardized mortality by Chinese standard population and by world standard population were 79.17/100 000, 107.02/100 000, respectively; and the cumulative mortality rate was 12.23% and cut rate was 139.75/100 000. Age-specific incidence among 0-34 years old population remained low; however, the incidence among 35-39 age group increased obviously (116.46/100 000, 954 cases). The incidence among 45-49 age group elevated even more sharply (272.97/100 000, 2388 cases) and finally reached the peak among 80-84 age group (1564.36/100 000, 2272 cases). Age-specific mortality arose among 40-44 age group (48.06/100 000, 424 cases) and reached its peak among 80-84 age group (1392.23/100 000, 2022 cases) as well. The most common types of cancer were lung cancer, gastric cancer, colorectal cancer, liver cancer, breast cancer, esophageal cancer, thyroid cancer, pancreatic cancer, cervical cancer and lymphoma, which accounted for 74.37% (22 763/30 613) of all new cancer cases.Lung cancer, liver cancer, gastric cancer, colorectal cancer, esophageal cancer, pancreatic cancer, leukemia, lymphoma, brain tumors and breast cancer accounted for 87.75% (14 848/16 920) of all cancer deaths. CONCLUSION: The incidence and mortality of cancer both increased in 2009 according to the statistics from cancer registry in Zhejiang province.Lung cancer, malignant tumor in digestive system and breast cancer were still the key challenges in cancer prevention and control. Meanwhile, the increased incidence of thyroid cancer should also be noticed.

State conversion based on terahertz plasmonics with vanadium dioxide coating controlled by optical pumping.

The state conversion and terahertz (THz) wave modulation based on a plasmonic device composed of silicon column arrays with vanadium dioxide (VO2) coating were experimentally demonstrated. For double 45° tilted optical pumping, a state conversion from dielectric photonic crystal (PC) to metallic PC was demonstrated due to the insulator-metal transition (IMT) of VO2 with the pump power increasing. In this process, a broadband intensity modulation with 70% modulation depth was achieved. Furthermore, for normally incident optical pumping, another state conversion from dielectric PC to plasmonic device was also demonstrated due to the partial IMT of VO2, and the out of plane PC resonance gradually changed to be plasmonic resonances. This device and its modulation scheme will be of great significance for potential THz applications.

Tunable nonreciprocal terahertz transmission and enhancement based on metal/magneto-optic plasmonic lens.

A tunable metal/magneto-optic plasmonic lens for terahertz isolator is demonstrated. Based on the magneto-optical effect of the semiconductor material and non-symmetrical structure, this plasmonic lens has not only the focusing feature but also nonreciprocal transmission property. Moreover, a transmission enhancement through this device greatly larger than that of the ordinary metallic slit arrays is contributed by the extraordinary optical transmission effect of the magneto surface plasmon polaritons. The results show that the proposed isolator has an isolation bandwidth of larger than 0.4THz and the maximum isolation of higher than 110dB, and its operating frequency also can be broadly tuned by changing the external magnetic field or temperature. This low-loss, high isolation, broadband tunable nonreciprocal terahertz transmission mechanism has a great potential for terahertz application systems.

Terahertz modulator based on insulator-metal transition in photonic crystal waveguide.

A terahertz modulator based on the insulator-metal transition (IMT) in a photonic crystal waveguide (PCW) coated by vanadium dioxide (VO2) film is proposed. The numerical simulations show that a dielectric state and a metallic state with quite different photonic band structures and transmission properties in the proposed PCW are reciprocally converted because of the IMT of VO2, and the pass-bands of this PCW are greatly shifted from 0.68 to 0.8 and 1.02 to 1.25 THz to 0.8-1.45 THz. This PCW significantly enhances the modulation depth and sensitivity compared with bare VO2 film. Extensive investigation demonstrates that the thickness of VO2 film greatly affects the IMT process in the PCW, and limits the ultimate modulation depth of the device. The proposed modulation scheme will be of great significance for potential THz applications.

[Incidence and mortality of larynx cancer in China during 2003-2007].

OBJECTIVE: To analyze the patterns of incidence and mortality on larynx cancer in China. METHODS: Data from 32 Cancer Registries in China were examined, sorted, and analyzed by the National Cancer Registry, to obtain the crude, Chinese national and world age-standardized rates (ASR) of incidence and mortality and their trends. RESULTS: The crude incidence and mortality rates of larynx cancer were 2.04/10(5) and 1.06/10(5) in China during 2003-2007. The rates were higher in males than those in females, and also higher in urban areas than those in rural areas. The highest Chinese ASRs of incidence and mortality of larynx cancer in 32 cancer registries in China were 2.08/10(5) in Zhongshan city, Guangdong province, and 1.58/10(5) in She county, Hebei province respectively. The trend of incidence and mortality of larynx cancer was stable from 2003 to 2007. CONCLUSION: Although both the incidence and mortality of larynx cancer in China were still in low level, comprehensive measures should be carried out to prevent the increase on both the incidence and mortality of larynx cancer.

4,7,8-Trimethyl-2H-chromen-2-one.

The mol-ecule of the title compound, C(12)H(12)O(2), is essentially planar, with a maximum deviation from the mean plane of all non-H atoms of 0.038 (1) Šfor the methyl C atom in the 8-position. The crystal structure is characterized by anti-parallel π-π stacking along the c axis, with centroid-centroid distances as short as 3.866 (1) Å. In the crystal, C-H⋯O hydrogen bonds connect the mol-ecules across the stacks into ribbons in the a-axis direction.