Good Stereo Research Articles

Directed copper-catalyzed C-H functionalization of unactivated olefins with azodicarbonamide compounds.

The copper-catalyzed strategy employing the 8-aminoquinoline directing group has proven to be a highly advantageous approach for functionalizing C-H bonds. In this study, we present the successful application of this strategy to accomplish Heck-type coupling reactions and construct β-lactam skeletons, simultaneously introducing a unique cyano functional group. The resulting Heck-type coupling products demonstrate good stereo- and region-selectivity. Initial mechanistic investigations indicate that the reaction proceeds via a radical coupling mechanism, exhibiting a wide substrate scope and delivering good yields.

Combination of bendamustine-azacitidine against Syk target of breast cancer: an in silico study

Breast cancer (BC) is the most serious and second leading cause of death in women worldwide. When breast cancer is diagnosed and treated early, the chance of long-term survival is up to 90%. On the other hand, 90% of BC patient deaths are due to metastasis and a lack of effective early diagnosis. The existing conventional chemotherapy provides negative feedback due to transportation barriers towards the action sites, multidrug resistance, poor bio-availability, non-specific delivery and systemic side effects on the healthy tissue. Syk protein Kinase has been reported in BC, as a tumor modulator, providing a pro-survival signal and also by restricting epithelial-mesenchymal transition, enhancing cell-cell interactions and inhibiting migration. In the present study, we explored the possibility of targeting BC by attenuating Syk protein Kinase. Hence, we have conjugated the hydrophobic Bendamustine (BEN) and hydrophilic Azacitidine (AZA) anticancer drugs to evaluate their efficacy against BC. The native drugs (BEN and AZA) and designed drug-drug conjugate (BEN-AZA) were docked with Syk protein. Then, the docked complex was performed for Binding Free Energy and Molecular Dynamics Simulations. Furthermore, DFT and ADME properties were carried out. The results revealed that the designed drug-drug conjugate has a better docking score, ΔGbind and admirable stability throughout the simulation when compared with native drugs. In DFT and ADME analyses, the designed drug-drug conjugate has shown good stereo electronic features and pharmaceutical relevant parameters than that of native drugs. The overall results suggested that the designed drug-drug conjugate may be a suitable candidate for BC treatment.Communicated by Ramaswamy H. Sarma

Synthesis, characterization and computational studies for (2′S*,3R*,3′S*,8a′R*)‐2′,3′‐bis(ethoxycarbonyl)‐2‐oxo‐2′,3′‐dihydro‐8a′H‐spiro[indoline‐3,1′‐indolizine]‐6′‐carboxylic acid and some derivatives

AbstractIn this article, we present advances related to 1,3‐dipolar cycloadditions of generated pyridinium ylides and apply these results to specific 1,3‐dipolar cycloaddition reactions with oxindole dipolarophiles. The ylide discussed in this article is generated from alkylation reactions between substituted pyridines and a primary electrophile. Cycloaddition reactions proceeding from pyridinium ylides and various oxindoles are reported with good stereo‐ and regioselectivity. Cycloaddition reactions take place by the overlap of the HOMO of the dipole and the LUMO of the dipolarophile when the two orbitals have similar energies, resulting in the formation of two new bonds. To get more insight into the reaction nature, a quantum chemical simulation was performed. A computational study is performed on the reactants (pyridinium ylides and oxindoles) and resulting cycloadducts. The present analysis reveals that the cycloaddition reactions under study can be classified in the normal electron demand category. Regioselectivity and mechanism of 1,3‐cycloaddition reactions are studied in the light of several theoretical approaches such as activation energy, Houk's rule based on the FMO theory, and the DFT reactivity indices.

Structural and functional characterization of a hypothetical protein in the RD7 region in clinical isolates of Mycobacterium tuberculosis — an in silico approach to candidate vaccines

BackgroundMycobacterium tuberculosis has been ravaging humans by inflicting respiratory tuberculosis since centuries. Bacillus Calmette Guerine (BCG) is the only vaccine available for tuberculosis, and it is known to be poorly effective against adult tuberculosis. Proteins belonging to the ESAT-6 family and PE/PPE family show immune responses and are included in different vaccine trials. Herein, we study the functional and structural characterization of a 248 amino acid long putative protein novel hypothetical protein 1 (NHP1) present in the RD7 region of Mycobacterium tuberculosis (identified first by subtractive hybridization in the clinical isolate RGTB123) using bioinformatics tools. ResultsPhysicochemical properties were studied using Expasy ProtParam and SMS software. We predicted different B-cell and T-cell epitopes by using the immune epitope database (IEDB) and also tested antigenicity, immunogenicity, and allergenicity. Secondary structure of the protein predicted 30% alpha helices, 20% beta strands, and 48% random coils. Tertiary structure of the protein was predicted using the Robetta server using the Mycobacterium smegmatis protein as the putative protein with homology. Structural evaluations were done with Ramachandran plot analysis, ProSA-web, and VERIFY3D, and with GalaxyWEB server, a more stable structure was validated with good stereo chemical properties. ConclusionThe present study of a subtracted genomic locus using various bioinformatics tools indicated good immunological properties of the putative mycobacterial protein, NHP1. Evidence obtained from the analyses of NHP1 using structure prediction tools strongly point to the fact that NHP1 is an ancient protein having flavodoxin folding structure with ATP binding sites. Positive scores were obtained for antigenicity, immunogenicity, and virulence too, implying the possibility of NHP1 to be a potential vaccine candidate. Such computational studies might give clues for developing newer vaccines for tuberculosis, which is the need of the hour.

Binocular vision training for professional athletes

Optimal visual abilities including stereo acuity seem to be an important issue in sports. There is increasing evidence that stereo acuity can be sustainably improved by digital vision training even for people with good stereo acuity. In this study 31male and female tennis players (professionals, young professionals, coaches and former professionals) completed at least 6training units each with 192 dynamic stereoscopic tasks (N = 1152) within 6 weeks including a4-option testwith different levels of difficulty on a3D screen at a distance of 5 m. The parameter reaction time and correctness at 15-300 arcseconds was determined. For amore precise representation of the reaction time improvement as afunction of the difficulty level, the parameter reaction time increase per stereo disparity reduction (ReST) was defined. Reaction time to 15 arcsecond stimuli significantly decreased from 3.9 s to 1.6 s (59%) as aresult of digital vision training. The correctness at 30 arcsecond stimuli significantly increased by 23%. The observed improvement in reaction time during vision training did not result in decreasing correctness when answering the visual questions. This represents an overall improvement in stereo vision. Dynamic visual training over 6 weeks improves stereoscopic performance including stereo acuity, response time and correctness.

Giant N-heterocyclic carbene-containing macrocycles for cobalt-catalysed hydroboration of alkynes.

Giant N-heterocyclic carbene-containing organic macrocycles larger than "Texas-sized" molecular boxes have been synthesized and structurally characterized. The new macrocycles were employed for the Co-NHC promoted syn-selective hydroboration of alkynes with good stereo- and regioselectivity.

Automatic Measurement of Elongation at Break of Cable Sheath Based on Binocular Vision

<p indent=0mm>In order to solve the problem of accuracy and automation of manual measurement for elongation at break of cable sheath, an automatic measurement based on binocular vision is proposed. Firstly, after the sample tensile video is collected, location method based on information entropy is used on the first frame for the center coordinates of two circle markers, if markers are correctly identified, the center coordinate is used as the marked point, otherwise the point closest to the center of circle in SURF feature points with good stereo matching results is selected as the marked point. Secondly, the marked points tracking based on L-K optical flow is used in the sampled video of sheath stretching process, the determination of the rough frame position of sheath breaking is based on the calculated three-dimensional coordinates and acceleration, then two sampling intervals are backtracked for frame by frame detection. Finally, the breaking frame is located precisely then elongation at break is calculated. The experimental results in the field of quality inspection of cable sheath show that the measured root mean square error of elongation at break is 7.13% which is lower than that of manual measurement method (21.84%), compared with the true values measured by 240 fps high-speed camera, and the processing speed of the method reaches 107.8 fps. Propose method can obviously improve the detection accuracy, speed and automation in practical application.

Neural markers of suppression in impaired binocular vision

Even after conventional patching treatment, individuals with a history of amblyopia typically lack good stereo vision. This is often attributed to atypical suppression between the eyes, yet the specific mechanism is still unclear. Guided by computational models of binocular vision, we tested explicit predictions about how neural responses to contrast might differ in individuals with impaired binocular vision. Participants with a history of amblyopia (N = 25), and control participants with typical visual development (N = 19) took part in the study. Neural responses to different combinations of contrast in the left and right eyes, were measured using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Stimuli were sinusoidal gratings with a spatial frequency of 3c/deg, flickering at 4 Hz. In the fMRI experiment, we also ran population receptive field and retinotopic mapping sequences, and a phase-encoded localiser stimulus, to identify voxels in primary visual cortex (V1) sensitive to the main stimulus. Neural responses in both modalities increased monotonically with stimulus contrast. When measured with EEG, responses were attenuated in the weaker eye, consistent with a fixed tonic suppression of that eye. When measured with fMRI, a low contrast stimulus in the weaker eye substantially reduced the response to a high contrast stimulus in the stronger eye. This effect was stronger than when the stimulus-eye pairings were reversed, consistent with unbalanced dynamic suppression between the eyes. Measuring neural responses using different methods leads to different conclusions about visual differences in individuals with impaired binocular vision. Both of the atypical suppression effects may relate to binocular perceptual deficits, e.g. in stereopsis, and we anticipate that these measures could be informative for monitoring the progress of treatments aimed at recovering binocular vision.

Vertical size disparity induces enhanced neural responses in good stereo observers

Stereoscopic three-dimensional vision requires cortical processing for horizontal binocular disparity between the two eyes’ retinal images. Behavioral and theoretical studies suggest that vertical size disparity is used to recover the viewing geometry and to generate the slant of a large surface. However, unlike horizontal disparity, the relation between stereopsis and neural responses to vertical disparity remains controversial. To determine the role of cortical processing for vertical size disparity in stereopsis, we measured neuromagnetic responses to disparities in people with good and poor stereopsis, using magnetoencephalography (MEG). Healthy adult participants viewed stereograms with a horizontal or vertical size disparity, and judged the perceived slant of the pattern. We assessed neural activity in response to disparities in the visual cortex and the phase locking of oscillatory responses including the alpha frequency range using MEG. For participants with good stereopsis, activity in the visual areas was significantly higher in response to vertical size disparity than to horizontal size disparity. The time–frequency analysis revealed that early neural responses to vertical size disparity were more phase-locked in good stereo participants than in poor stereo participants. These results provide neuromagnetic evidence that vertical-size disparity processing plays a role in good stereo vision.

A critical analysis of satellite stereo pairs for digital surface model generation and a matching quality prediction model

The geometric analysis and data acquisition of satellite photogrammetric images are often regarded as a direct extension of traditional aerial photogrammetry, with the only difference being the sensor model (linear array vs. central perspective). The intersection angle (or base-height ratio) between two images is seen as the most important metadata of stereo pairs, which directly relates to the base-high ratio and texture distortion in the parallax direction, thus both affecting the horizontal and vertical accuracy. State-of-the-art DIM algorithms were reported to work best for narrow baseline stereos (small intersection angle), e.g. Semi-Global Matching empirically takes 15–25° as “good” intersection angles. However, our experiments found that the intersection angle is not the only determining factor, as the same DIM algorithm applied to stereo pairs of the same area with similar and good intersection angle may produce point clouds with dramatically different accuracy (demonstrated in the graphical abstract). This raises a very practical and often asked question: what factors constitute a good satellite stereo pair for DIM algorithms? In this paper, we provide a comprehensive analysis on this matter by performing stereo matching using the very typical and widely-used Semi-Global Matching (SGM) with a Census cost over 1000 satellite stereo pairs of the same region with different meta-parameters including their intersection, off-nadir, sun elevation & azimuth angles, completeness and time differences, thus to offer a thorough answer to this question. Our conclusion has specifically outlined an important yet often ignored factor – the Sun-angle difference to be one decisive in determining good stereo pair. Based on the analytical results, we propose a simple idea by training a support vector machine model for predicting potential stereo matching quality (i.e. potential level of accuracy and completeness given a stereo pair). Experiments have shown that the model is well-suited and generalized for multi-stereo 3D reconstruction, evidenced by a comparative analysis against three other strategies: (1) pair selection based on an example patch where partial ground-truth data is available for computing a priori ranking (2) based on intersection angles and (3) based on a recent algorithm using intersection angle, off-nadir angle and time intervals. This work will potentially provide a valuable reference to researchers working on multi-view satellite image reconstruction, as well as for practitioners minimizing costs for high-quality large-scale mapping. The trained model is made available to the academic community upon request.

7.2: Invited Paper: Quantification and Modulation of Stereopsis in Humans

Binocular vision in general and stereopsis in particular are fundamental to human vision and visual actions. It is widely thought that about 5% of the population have a lazy eye and lack stereo vision, so it is often supposed that most of the population (95%) have good stereo abilities. We show that this is not the case; 68% have good to excellent stereo (the haves) and 32% have moderate to poor stereo (the have‐nots). Why so many people lack good 3‐D stereo vision is unclear but it is likely to be neural and reversible.Interocular suppression and stereopsis are two important binocular functions. To date, it still remains unclear about the relationship between them. Here, we use the binocular phase combination paradigm and a comparable paradigm to provide a normative dataset for perceptual eye dominance and stereo acuity in 142 normal‐sighted human adults and analyze their correlation. We show that our eye dominance and stereopsis are not strongly correlated in the normalsighted subjects. These results thus support the idea that the binocular phase combination and stereopsis may be limited by different factors in normal‐sighted adults.At present there is no good way of reliably measuring stereopsis in the clinic other than the standard book tests designed for children. These are convenient but coarsely quantized in disparity with no measure of variance. This makes it difficult to be able to assess the significance of differences from visit to visit contingent on therapy. We report an iPod app that has been developed from laboratory studies of normal stereopsis, to measure stereo in the clinic that is not limited by these factors. The application enables measurements over the wide disparity range and not just at the finest disparities. In addition, it allows changes in stereopsis of the order of 1.9 to be statistically distinguished.Luminance plays a modulating role in the processes of several visual tasks, which in turn provides significant information for the understanding of visual processing. To study the relationship between luminance and stereopsis, we manipulated the mean luminance seen by both eyes or the interocular difference in mean luminance by using ND filters placed in front of both eyes or just one eye respectively. We found that disparity processing was little affected by a binocular change in luminance, but was greatly affected by a luminance mismatch between the two eyes. To investigate its origin we manipulated two factors, the temporal synchrony between the two eyes and the interocular contrast. Both factors are implicated in the loss of stereo performance when the mean luminance is different between the eyes, suggesting an underlying explanation in terms of temporal low‐pass filtering resulting in the combination of a luminance‐dependent temporal delay and a luminance‐dependent change in contrast gain.These results add to our knowledge of stereopsis and have therapeutic potential in re‐establishing stereopsis in patients with binocular disorders.

Stereo OCT angiography in macular diseases

PurposeTo present stereo optical coherence tomography angiography (SD OCT‐A) images of patients with different macular pathologies.MethodsA series of patients with macular pathologies underwent OCT‐A imaging with the Heidelberg Engineering SPECTRALIS OCT2 device. In addition, these patients underwent OCT B and C scans, color fundus photographies and fluorescein and ICG angiographies. The OCT‐A images were then computerized in a manner to give stereo images. Slabs of different thicknesses were analyzed and are presented.ResultsThirty seven eyes with different macular diseases (10 exsudative AMD, 16 diabetic retinopathies, 10 retinal venous occlusions, 1 acute macular placoid pigmented epitheliopathy) were included and analyzed.Stereo OCT‐A allowed to show the vascular abnormality and its impact on the retina and the choroid. The swelling of the retina was highlighted in stereo viewing.ConclusionsStereo OCT‐A is a new additive technique to OCT imaging. It gives a global assessment of the central retina pathology highlighting retinal swelling.This technique needs perfect segmentation to achieve good stereo images and improvements are currently needed.

Olefination of Electron-Deficient Alkenes with Allyl Acetate: Stereo- and Regioselective Access to (2Z,4E)-Dienamides.

A Ru-catalyzed direct olefination of electron-deficient alkenes with allyl acetate via C-H bond activation is disclosed. By using N,N-disubstituted aminocarbonyl as the directing group, this external oxidant-free protocol resulted in high reaction efficiency and good stereo- and regioselectivities, which opens a novel synthetic passway for access to (Z,E)-butadiene skeletons.

입체 시력이 양호한 사람과 불량인 사람간의 입체시 융합 가능 영역 비교

Purpose: This study investigated differences in stereoscopic fusional area between those with good and poor stereoacuity in viewing stereoscopic displays. Methods: Stereo acuity of 39 participants (18 males and 21 females, 23.6±3.15years) was measured with the random dot stereo butterfly method. Participants with stereo-blindness were not included.Stereoscopic fusional area was measured using stereoscopic stimulus by varying the amount of horizontal disparity in astereoscopic 3D TV. Participants were divided into two groups of good and poor stereo acuity. Criterion for good stereoacuity was determined as less than 60 arc seconds. Measurements arising from the participants were statisticallyanalyzed. Results: 26 participants were measured to have good stereo acuity and 13 participants poor stereo acuity. Incase of the stereoscopic stimulus farther than the fixation point, threshold of horizontal disparity for those with poorstereo acuity were measured to be smaller than the threshold for those with good stereo acuity, with a statisticallysignificant difference. On the other hand, there was no statistically significant difference between the two groups, in caseof the stereoscopic stimulus nearer to the fixation point. Conclusions: In viewing stereoscopic displays, the boundary ofstereoscopic fusional area for the poor stereo acuity group was smaller than the boundary of good stereo acuity grouponly for the range behind the display. Hence, in viewing stereoscopic displays, participants with poor stereo acuity wouldhave more difficulty perceiving the fused image at farther distances compared to participants with good stereo acuity.Key words: Stereo acuity, Stereoscopic fusional area, Stereoscopic display

Palladium-Catalyzed 1,3-Difunctionalization Using Terminal Alkenes with Alkenyl Nonaflates and Aryl Boronic Acids.

A Pd-catalyzed 1,3-difunctionalization of terminal alkenes using 1,1-disubstituted alkenyl nonaflates and arylboronic acid coupling partners is reported. This transformation affords allylic arene products that are difficult to selectively access using traditional Heck cross-coupling methodologies. The evaluation of seldom employed 1,1-disubstituted alkenyl nonaflate coupling partners led to the elucidation of subtle mechanistic features of π-allyl stabilized Pd-intermediates. Good stereo- and regioselectivity for the formation of 1,3-addition products can be accessed through a minimization of steric interactions that emanate from alkenyl nonaflate substitution.

ChemInform Abstract: Stereo‐ and Chemoselective Cross‐Coupling Between Two Electron‐Deficient Acrylates: An Efficient Route to (Z,E)‐Muconate Derivatives.

A Ru-catalyzed direct oxidative cross-coupling reaction of acrylates was developed. It offers a straightforward and atom-economical protocol for the synthesis of functionalized (Z,E)-muconate derivatives in moderate to good yields with good stereo- and chemoselectivities. The conjugated muconates bearing differentiable terminal functionality can be selectively transformed into versatile synthetic intermediates widely used in organic synthesis.

Stereo Vision: The Haves and Have-Nots.

Animals with front facing eyes benefit from a substantial overlap in the visual fields of each eye, and devote specialized brain processes to using the horizontal spatial disparities produced as a result of viewing the same object with two laterally placed eyes, to derived depth or 3-D stereo information. This provides the advantage to break the camouflage of objects in front of similarly textured background and improves hand eye coordination for grasping objects close at hand. It is widely thought that about 5% of the population have a lazy eye and lack stereo vision, so it is often supposed that most of the population (95%) have good stereo abilities. We show that this is not the case; 68% have good to excellent stereo (the haves) and 32% have moderate to poor stereo (the have-nots). Why so many people lack good 3-D stereo vision is unclear but it is likely to be neural and reversible.

Accurate stereo matching by two-step energy minimization.

In stereo matching, cost-filtering methods and energy-minimization algorithms are considered as two different techniques. Due to their global extent, energy-minimization methods obtain good stereo matching results. However, they tend to fail in occluded regions, in which cost-filtering approaches obtain better results. In this paper, we intend to combine both the approaches with the aim to improve overall stereo matching results.We show that a global optimization with a fully connected model can be solved by cost-filtering methods. Based on this observation, we propose to perform stereo matching as a two-step energy-minimization algorithm. We consider two Markov random field (MRF) models: 1) a fully connected model defined on the complete set of pixels in an image and 2) a conventional locally connected model. We solve the energy-minimization problem for the fully connected model, after which the marginal function of the solution is used as the unary potential in the locally connected MRF model. Experiments on the Middlebury stereo data sets show that the proposed method achieves the state-of-the-arts results.

Stereo- and chemoselective cross-coupling between two electron-deficient acrylates: an efficient route to (Z,E)-muconate derivatives.

A Ru-catalyzed direct oxidative cross-coupling reaction of acrylates was developed. It offers a straightforward and atom-economical protocol for the synthesis of functionalized (Z,E)-muconate derivatives in moderate to good yields with good stereo- and chemoselectivities. The conjugated muconates bearing differentiable terminal functionality can be selectively transformed into versatile synthetic intermediates widely used in organic synthesis.

Well-defined NHC-rhodium hydroxide complexes as alkenehydrosilylation and dehydrogenative silylation catalysts

Alkene hydrosilylation and dehydrogenative silylation reactions, mediated by [Rh(cod)(NHC)(OH)] complexes (cod = 1,5-cyclooctadiene; NHC = N-heterocyclic carbene) are described. The study details a comparison of the catalytic activity and steric characteristics of four rhodium complexes bearing different NHC ligands. The novel [Rh(cod)(Ii-PrMe)(OH)] complex (Ii-PrMe = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidine) was designed to improve the reactivity of Rh(I)-hydroxides and proved to be a successful promoter of hydrosilylation and dehydrogenative silylation, displaying good stereo- and regiocontrol.