Internal feedback in the cortical perception-action loop enables fast and accurate behavior.

Animals move smoothly and reliably in unpredictable environments. Models of sensorimotor control, drawing on control theory, have assumed that sensory information from the environment leads to actions, which then act back on the environment, creating a single, unidirectional perception-action loop. However, the sensorimotor loop contains internal delays in sensory and motor pathways, which can lead to unstable control. We show here that these delays can be compensated by internal feedback signals that flow backward, from motor toward sensory areas. This internal feedback is ubiquitous in neural sensorimotor systems, and we show how internal feedback compensates internal delays. This is accomplished by filtering out self-generated and other predictable changes so that unpredicted, actionable information can be rapidly transmitted toward action by the fastest components, effectively compressing the sensory input to more efficiently use feedforward pathways: Tracts of fast, giant neurons necessarily convey less accurate signals than tracts with many smaller neurons, but they are crucial for fast and accurate behavior. We use a mathematically tractable control model to show that internal feedback has an indispensable role in achieving state estimation, localization of function (how different parts of the cortex control different parts of the body), and attention, all of which are crucial for effective sensorimotor control. This control model can explain anatomical, physiological, and behavioral observations, including motor signals in the visual cortex, heterogeneous kinetics of sensory receptors, and the presence of giant cells in the cortex of humans as well as internal feedback patterns and unexplained heterogeneity in neural systems.

The effect of luteinizing hormone changes in GnRH antagonist protocol on the outcome of controlled ovarian hyperstimulation and embryo transfer.

BACKGROUD: To investigate the effect of Luteinizing hormone (LH) level changes on the outcomes of controlled ovarian hyperstimulation (COH) and embryo transfer (ET) in gonadotropin-releasing hormone antagonist (GnRH-ant) protocol. METHODS: A total of 721 patients undergoing GnRH-ant protocol COH for the first IVF/ICSI cycles were retrospectively analyzed. COH process were divided into 2 stages, before (stage 1) and after (stage 2) the GnRH-ant initiation, and each with 5 groups basing on LH levels: LH decreased more than 50% (groups A1, A2), decreased 25-50% (groups B1, B2), change less than 25% (groups C1, C2), increased 25-50% (groups D1, D2), and increased more than 50% (groups E1, E2). RESULTS: There were no significant differences among groups of stage1 regarding COH and ET outcomes. For stage 2, the more obvious the decrease of LH level, the more the number of oocytes retrieved, mature oocytes, fertilized oocytes, embryos cleavaged and the numbers of embryo available (P < 0.05), but without significant differences regarding ET outcomes. We also found the freeze-all rate in Group A2 was higher (P < 0.001). CONCLUSION: LH level changes before GnRH-ant addition were not related to COH and ET outcomes. LH level changes after the addition of GnRH-ant were related to the outcome of COH, and no significant differences were found relating to ET outcomes.

Dense hyperthermic intraperitoneal chemotherapy with cisplatin in patients with stage III serous epithelial ovarian cancer: a retrospective study.

BACKGROUND: To investigate the efficacy and safety of interval debulking surgery (IDS) combined with dense hyperthermic intraperitoneal chemotherapy (HIPEC) with cisplatin in Chinese patients with FIGO stage III serous epithelial ovarian cancer (EOC). METHODS: This retrospective single-center study reviewed the demographic and clinical data of 197 patients with primary FIGO stage III serous EOC who were treated with IDS with (n = 121) or without (n = 76, control group) dense HIPEC between January 2012 and April 2017. The co-primary endpoints were progression-free survival (PFS) and overall survival (OS), and the secondary endpoint was the occurrence of adverse events. RESULTS: The median PFS was 24 months in the IDS plus dense HIPEC group, whereas it was 19 months in the IDS alone group (hazard ratio [HR] 0.46, 95% confidence interval [CI]: 0.33-0.65, p = 0.000). The median OS in patients treated with IDS plus dense HIPEC (51 months) was significantly longer than that in patients treated with IDS alone (40 months, HR 0.52, 95% CI: 0.35-0.78, p = 0.001). The demographic and preoperative clinical characteristics of these two groups were comparable (p > 0.05). In the IDS alone group, no adverse events were recorded in 42 (55.3%) of the 76 patients, and 14 (18.4%) patients were reported to have grade III/IV adverse events. In the IDS plus dense HIPEC group, no adverse events were recorded in 55 (45.5%) of the 121 patients, and 23 (19.0%) patients were reported to have grade III/IV adverse events. No postoperative deaths occurred within 30 days in either group and neither did severe fatal complications in the IDS plus dense HIPEC group. CONCLUSIONS: IDS plus dense HIPEC with cisplatin in Chinese patients with FIGO stage III serous EOC is associated with improved survival and is reasonably well tolerated by patients.

Anchored atomic tungsten on a B40 cage: a highly active and selective single-atom catalyst for nitrogen reduction.

In comparison with the prevalent 2D material-supported single atom catalysts (SACs), the design and fabrication of SACs with single molecule substrates are still challenging. Here we introduce a new type of SAC in which a recently identified all-boron fullerene B40 is employed as the support and its catalytic performance toward the nitrogen reduction reaction (NRR) process is explored in theory. Taking advantage of the novel heptagonal ring substructure on the sphere and the electron-deficient nature of boron, the atomic metals are facile to reside on B40 to form atomically dispersed η7-B40M exohedral complexes. Among a series of candidates, originating from the proper metal-adsorbate interactions, the atomic tungsten-decorated B40W is screened out as the most feasible catalyst for the NRR with a low over-potential and high selectivity to passivate the competitive hydrogen evolution process.

Core-shell structured Co@CN nanocomposites as highly efficient dual function catalysts for reduction of toxic contaminants and hydrogen evolution reaction.

In this study, we have reported nitrogen-doped graphite C coated Co nanocomposite (Co@CN) catalysts synthesized by one-step arc discharge method. The surface compositions, morphologies and the catalytic properties of the Co@CN nanocomposites were studied minutely. The results reveal that the prepared Co@CN nanocomposites have typical core-shell structure and show highly efficient catalytic performance in a reduction of 4-nitrophenol (4-NP), rhodamine and methylene blue. Their rate constant (Kapp) is 0.074 s-1 in a reduction of 4-NP, which is much higher than that of reported transition metal-based catalysts. Moreover, the overpotential of Co@CN is only 96 mV at a current density of 10 mA cm-2 in alkaline solution, showing high electrocatalytic activities in the hydrogen evolution reaction. The excellent synergistic effect between nitrogen-doped graphite C shell and magnetic Co core enables the Co@CN nanocomposites catalysts to hold abundant active sites and to transmit rapidly electron ability, resulting in Co@CN nanocomposite catalysts having a highly efficient catalytic nature.

Defective h-BN sheet embedded atomic metals as highly active and selective electrocatalysts for NH3 fabrication via NO reduction.

NO electrochemical reduction (NOER) is a promising route for the removal of pollutant NO and the production of ammonia. In this work, by means of first-principles computations, we designed a series of single atom catalysts consisting of atomic transition metals anchored onto defective hexagonal boron nitride (h-BN) with boron vacancies (TM@h-BN). Among all nine candidates, our results revealed that Cu@h-BN and Ni@h-BN showed excellent NOER performances with relatively low limiting potentials of 0.23 and 0.31 V, respectively, which are comparable to (or even better than) that of the benchmark Pt catalyst (0.25 V). Moreover, Cu@h-BN and Ni@h-BN can significantly inhibit the competitive hydrogen evolution reaction, suggesting that the promoted ammonia formation is a low-potential and highly selective process.

Modeling the Effects of Meteorological Factors and Unreported Cases on Seasonal Influenza Outbreaks in Gansu Province, China.

Influenza usually breaks out seasonally in temperate regions, especially in winter, infection rates and mortality rates of influenza increase significantly, which means that dry air and cold temperatures accelerate the spread of influenza viruses. However, the meteorological factors that lead to seasonal influenza outbreaks and how these meteorological factors play a decisive role in influenza transmission remain unclear. During the epidemic of infectious diseases, the neglect of unreported cases leads to an underestimation of infection rates and basic reproduction number. In this paper, we propose a new non-autonomous periodic differential equation model with meteorological factors including unreported cases. First, the basic reproduction number is obtained and the global asymptotic stability of the disease-free periodic solution is proved. Furthermore, the existence of periodic solutions and the uniformly persistence of the model are demonstrated. Second, the best-fit parameter values in our model are identified by the MCMC algorithm on the basis of the influenza data in Gansu province, China. We also estimate that the basic reproduction number is 1.2288 (95% CI:(1.2287, 1.2289)). Then, to determine the key parameters of the model, uncertainty and sensitivity analysis are explored. Finally, our results show that influenza is more likely to spread in low temperature, low humidity and low precipitation environments. Temperature is a more important factor than relative humidity and precipitation during the influenza epidemic. In addition, our results also show that there are far more unreported cases than reported cases.

Method validation of Q-PCR detection of host residual DNA in antibody drug based on protein A magnetic beads.

The residual DNA derived from host cells in antibody drugs have potential safety risks. In this paper, the antibody in the test sample was removed by magnetic bead separation method, and the residual DNA were quantitatively determined by Q-PCR method. The residual DNA in the sample was analyzed according to the standard curve. We validated the species specificity, accuracy, precision, quantitative restrictions, reproducibility of this method. The results showed the linearrange was of 1 × 10-1～1 × 102 pg/µL and the curve linear was good, this method can specifically detect CHO cell DNA. Compared with the method of extracting residual DNA by magnetic beads, the method has the advantages of simplicity, rapidity and low cost, and can be used for quantitative determination of the residual host cell DNA in antibody drugs producted by CHO cells.

Increased pregnancy complications following frozen-thawed embryo transfer during an artificial cycle.

PURPOSE: This study aimed to clarify the risks of adverse pregnancy outcomes in patients and their offspring after frozen embryo transfer (FET) during an artificial cycle (AC). METHODS: We conducted a retrospective cohort study that included all FET cycles and subsequent deliveries in a single centre between August 2013 and March 2016. Pregnancy, obstetric and neonatal outcomes were compared among patients treated during an AC or a natural cycle with luteal phase support (NC-LPS). Multivariate logistic regression was performed to evaluate the relationship between endometrial preparation schemes and pregnancy, obstetric and neonatal outcomes. RESULTS: AC-FET was not a significant risk factor for clinical pregnancy rate, multiple birth rate or miscarriage rate after adjusting for potential confounders. However, AC-FET was a significant risk factor for ectopic pregnancy rate (adjusted odds ratio (AOR), 1.738; 95% confidence interval (CI), 1.086-2.781) and live birth rate (AOR, 0.709; 95% CI, 0.626-0.802). Regarding obstetric outcomes, AC-FET was found to be associated with an increased risk for hypertension disorder (AOR, 1.780; 95% CI, 1.262-2.510) and caesarean section (AOR, 1.507; 95% CI, 1.195-1.900). In multiples, birth weight (2550 g (2150-2900 g) in AC-FET vs. 2600 g (2350-2900 g) in NC-LPS; P = 0.023), gestational age (36.6 weeks (35.3-37.6 weeks) vs. 37.1 weeks (36.1-37.9 weeks); P < 0.001), and z-score (- 0.5 (- 1.1, - 0.0) vs. - 0.4 (- 1.0, 0.2); P = 0.009) were higher in the NC-LPS group than in the AC-FET group, although there were no differences in these variables among singletons. CONCLUSION: Compared with NC-LPS, AC-FET seemed to have a negative effect on obstetric outcomes.

The risk of placenta previa and cesarean section associated with a thin endometrial thickness: a retrospective study of 5251 singleton births during frozen embryo transfer in China.

PURPOSE: To determine whether the endometrial thickness (EMT) affects the occurrence of obstetric complications and neonatal outcomes in frozen embryo transfer (FET). METHODS: We conducted a retrospective study that included singleton deliveries (N = 5251) resulting from FET in a single center between August 2013 and March 2016. Obstetric complications and neonatal outcomes were compared among patients with different EMTs, which were measured the day before embryo thawing. The women were divided into three groups based on the EMT: group 1: < 9 mm; group 2: 9-12 mm; group 3: > 12 mm. Multiple logistic regression and subgroup analyses were performed to determine the potential confounding factors. RESULTS: The incidence of placenta previa in groups 1, 2, and 3 was 3.8, 1.0 and 0.5%, respectively, and that of cesarean section was 87.0, 78.3 and 72.0%, respectively (both P < 0.001). The gestational age and birth weight increased from group 1 to group 3 (both P < 0.001). After adjusting for confounders, a thicker EMT was found to be associated with a decreased risk of placenta previa (adjusted odds ratio (aOR) 0.798; 95% confidence interval (95% CI) 0.651-0.979; P = 0.031) and with a decreased risk of cesarean section (aOR 0.926; 95% CI 0.889-0.965; P < 0.001). Regarding the incidence of placenta previa, compared to women in group 3, women in group 1 had an aOR of 6.208 (95% CI 2.169-17.766; P = 0.001), and women in group 2 had an aOR of 1.862 (95% CI 0.851-4.076; P = 0.120). Regarding the incidence of cesarean section, compared to women in group 3, women in group 1 had an aOR of 2.111 (95% CI 1.415-3.455; P < 0.001), and women in group 2 had an aOR of 1.293 (95% CI 1.128-1.481; P < 0.001). Subgroup analyses showed similar results. CONCLUSIONS: Our results demonstrate that a thin endometrial lining is associated with adverse obstetric and neonatal outcomes and might be related to poor placentation.

Formation of Stone-Wales edge: Multistep reconstruction and growth mechanisms of zigzag nanographene.

Although the existence of Stone-Wales (5-7) defect at graphene edge has been clarified experimentally, theoretical study on the formation mechanism is still imperfect. In particular, the regioselectivity of multistep reactions at edge (self-reconstruction and growth with foreign carbon feedstock) is essential to understand the kinetic behavior of reactive boundaries but investigations are still lacking. Herein, by using finite-sized models, multistep reconstructions and carbon dimer additions of a bared zigzag edge are introduced using density functional theory calculations. The zigzag to 5-7 transformation is proved as a site-selective process to generate alternating 5-7 pairs sequentially and the first step with largest barrier is suggested as the rate-determining step. Conversely, successive C2 insertions on the active edge are calculated to elucidate the formation of 5-7 edge during graphene growth. A metastable intermediate with a triple sequentially fused pentagon fragment is proved as the key structure for 5-7 edge formation. © 2017 Wiley Periodicals, Inc.

Effect of Substituents and Initial Degree of Functionalization of Alkylated Single-Walled Carbon Nanotubes on Their Thermal Stability and Photoluminescence Properties.

Alkylated single-walled carbon nanotubes (SWNTs) have been thermally treated to determine the influence of substituents and the degree of functionalization on their thermal stability and photoluminescence (PL) properties. Alkylated SWNTs were prepared by treating SWNTs with sodium naphthalenide and alkyl bromide. The defunctionalization of the alkylated SWNTs was monitored by absorption and Raman spectra. Selective recovery of the characteristic absorption and radial breathing mode peaks was observed during the thermal treatment, which indicates that the thermal stability of the alkylated SWNTs decreases with increases in SWNT diameter and degree of functionalization. n-Butylated and phenethylated SWNTs showed higher thermal stability than sec-butylated and benzylated SWNTs for a similar degree of functionalization, respectively. The diameter selectivity and effect of substituents on the thermal elimination reaction were confirmed by density functional theory. In addition, it was shown that the initial degree of functionalization of the alkylated SWNTs, with the alkyl group and degree of functionalization being kept constant after thermal treatment, strongly affects their PL properties; Stokes shift, and PL peak intensity.

Fused-Pentagon-Configuration-Dependent Electron Transfer of Monotitanium-Encapsulated Fullerenes.

We introduce monotitanium-based endohedral metallofullerenes (EMFs) using density functional theory calculations. Isomeric C64 fullerenes are initially employed as hosts, and Ti@C64 species show novel features on the electronic structures. Energetically, the preference of titanium residing on triple-fused-pentagon subunits is proposed in theory. More importantly, different from current knowledge on mono-EMFs, electron transfer between titanium and carbon cages is not unified but is essentially dependent on the pentagon distribution of the binding sites, giving rise to variations of the cationic titanium of Ti@C64. Such selective electron-transfer character is extended to the study of the encapsulation of other neighboring metal atoms (i.e., calcium and scandium). Because of their different capabilities to accept d electrons, fullerene cages with distinct fused-pentagon motifs show selective metal encapsulation characters. In addition, some other fullerenes (C44-C48 and C82) are selected as hosts to study the electron-transfer behavior of titanium in smaller fullerenes and larger systems without pentagon adjacency.

Concave binding of cationic Li to quadrannulene.

Binding of Li+ to quadrannulene and its influence on buckybowl functionalization are introduced. The concave-trapped Li+ acts as a Lewis acid and the rate of Diels-Alder cycloaddition is enhanced 108 times. A sandwiched bowl-Li+-bowl structure is stabilized via concave-cation-convex interactions, indicating the promoted role of Li+ in buckybowl assembly.

D2d(23)-C84 versus Sc2C2@D2d(23)-C84: Impact of Endohedral Sc2C2 Doping on Chemical Reactivity in the Photolysis of Diazirine.

We compared the chemical reactivity of D2d(23)-C84 and that of Sc2C2@D2d(23)-C84, both having the same carbon cage geometry, in the photolysis of 2-adamantane-2,3'-[3H]-diazirine, to clarify metal-atom doping effects on the chemical reactivity of the carbon cage. Experimental and computational studies have revealed that the chemical reactivity of the D2d(23)-C84 carbon cage is altered drastically by endohedral Sc2C2 doping. The reaction of empty D2d(23)-C84 with the diazirine under photoirradiation yields two adamantylidene (Ad) adducts. NMR spectroscopic studies revealed that the major Ad monoadduct (C84(Ad)-A) has a fulleroid structure and that the minor Ad monoadduct (C84(Ad)-B) has a methanofullerene structure. The latter was also characterized using X-ray crystallography. C84(Ad)-A is stable under photoirradiation, but it interconverted to C84(Ad)-B by heating at 80 °C. In contrast, the reaction of endohedral Sc2C2@D2d(23)-C84 with diazirine under photoirradiation affords four Ad monoadducts (Sc2C2@C84(Ad)-A, Sc2C2@C84(Ad)-B, Sc2C2@C84(Ad)-C, and Sc2C2@C84(Ad)-D). The structure of Sc2C2@C84(Ad)-C was characterized using X-ray crystallography. Thermal interconversion of Sc2C2@C84(Ad)-A and Sc2C2@C84(Ad)-B to Sc2C2@C84(Ad)-C was also observed. The reaction mechanisms of the Ad addition and thermal interconversion were elucidated from theoretical calculations. Calculation results suggest that C84(Ad)-B and Sc2C2@C84(Ad)-C are thermodynamically favorable products. Their different chemical reactivities derive from Sc2C2 doping, which raises the HOMO and LUMO levels of the D2d(23)-C84 carbon cage.

Regioselective multistep reconstructions of half-saturated zigzag carbon nanotubes.

The open edge reconstruction of half-saturated (6,0) zigzag carbon nanotube (CNT) was introduced by density functional calculations. The multistep rearrangement was demonstrated as a regioselective process to generate a defective edge with alternating pentagons and heptagons. Not only the thermal stability was found to be enhanced significantly after reconstruction but also the total spin of CNT was proved to be reduced gradually from high-spin septet to close-shell singlet, revealing the critical role of deformed edge on the geometrical and magnetic properties of open-ended CNTs. Kinetically, the initial transformation was confirmed as the rate-determining step with relatively the largest reaction barrier and the following steps can take place spontaneously. © 2016 Wiley Periodicals, Inc.

Ureaplasma urealyticum and Mycoplasma hominis infections and semen quality in 19,098 infertile men in China.

OBJECTIVE: This study aimed to determine the incidence of Ureaplasma urealyticum and Mycoplasma hominis infections in infertile and fertile men and to investigate their effects on the semen quality. The study also aimed to analyze the drug susceptibility of UU and MH to provide guidance for reasonable antibiotic use. METHODS: A total of 19,098 semen specimens were obtained from infertile men at our hospital from January to December 2014. In addition to these specimens, 3368 semen specimens of sperm were obtained from donors at the sperm bank of our hospital from January 2011 to December 2014. Semen analysis was performed using the methods outlined by the World Health Organization. RESULTS: The prevalence of UU and MH significantly differed between infertile and fertile men. The mean progressive motility, total motility, and normal forms in the semen samples of infertile males positive for UU significantly differed from the corresponding values of uninfected men. However, the semen parameters did not differ between MH-infected and uninfected men. In the antibiotic sensitivity test, UU, MH, and UU mixed with MH were all found susceptible to doxycycline and josamycin with drug resistance rates below 6 %, but both species were highly resistant to ciprofloxacin. CONCLUSIONS: Clinical assessment revealed a significant relationship between UU and MH infections and male infertility. UU was found to significantly affect sperm quality, but this was not the case with MH. Doxycycline and josamycin should be preferred for clinically treating UU and MH infections.

Unconventional Electronic Structure and Chlorination/Dechlorination Mechanisms of (#1911)C64 Fullerene.

We report a computational work on the electronic structure and derivatization of (#1911)C64. By means of computations based on density functional theory, we find that (#1911)C64 in states of closed-shell singlet (CS), open-shell singlet (OS), and triplet are iso-energetic with an energy difference less than 0.1 kcal mol(-1). The regioselective chlorine additions on CS, OS, and triplet C64 are studied, and the formation of experimentally observed C64Cl4 and C64Cl8 have been successfully elucidated for the first time. In addition, the dechlorination processes of formed chlorofullerenes are also explored. In contrast to the radical Cl addition, the reverse reaction is a themolysis process, and the decomposition sequence is proved to be simply determined by the C-Cl bond length.

From Mononuclear to Dinuclear Iridium(III) Complex: Effective Tuning of the Optoelectronic Characteristics for Organic Light-Emitting Diodes.

Phosphorescent dinuclear iridium(III) complexes that can show high luminescent efficiencies and good electroluminescent abilities are very rare. In this paper, highly phosphorescent 2-phenylpyrimidine-based dinuclear iridium(III) complexes have been synthesized and fully characterized. Significant differences of the photophysical and electrochemical properties between the mono- and dinuclear complexes are observed. The theoretical calculation results show that the dinuclear complexes adopt a unique molecular orbital spatial distribution pattern, which plays the key role of determining their photophysical and electrochemical properties. More importantly, the solution-processed organic light-emitting diode (OLED) based on the new dinuclear iridium(III) complex achieves a peak external quantum efficiency (η(ext)) of 14.4%, which is the highest η(ext) for OLEDs using dinuclear iridium(III) complexes as emitters. Besides, the efficiencies of the OLED based on the dinuclear iridium(III) complex are much higher that those of the OLED based on the corresponding mononuclear iridium(III) complex.

Bingel-Hirsch reaction mechanisms on TiSc2N@Ih-C80: the role of endohedral titanium nitride.

Recently, two unconventional singly bonded monoadducts of mixed-metal nitride clusterfullerene TiSc2N@Ih-C80 have been synthesized. Herein, the site-selectivity and kinetic processes of Bingel-Hirsch reactions are explored by density functional theory calculations. Because of the rotation of the inner TiSc2N unit, two different types of singly bonded monoadducts (named 666 and 566 adducts) are clarified. Meanwhile, the two functionalized sites are situated above the Ti-Sc edge of the inner cluster in singly bonded adducts. Addition on the triple-fused-hexagon site (6-6-6 site) is found to be kinetically preferred, which can be attributed to the more positive charge of the carbon in the 6-6-6 site. In addition, we investigated the formation process of two conventional cycloadducts. A preference for the addition on the bridged hexagon-hexagon bond is concluded in theory, furthermore, one Sc atom instead of the Ti atom is pointing to the functionalized bond for the lowest-energy orientational product.