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Purpose: To evaluate choroidal changes in central serous chorioretinopathy (CSCR) patients after water-drinking test (WDT). Methods: This prospective study included treatment-naïve acute and chronic CSCR eyes and healthy controls. Intraocular pressure and optical coherence tomography measurements with choroidal vascular index (CVI) measurements were done at baseline. Patients were asked to drink 1 L of water, and tests were repeated at 15, 30, and 45 min. Results: Fifty-six eyes from 42 patients were enrolled. Choroidal area, luminal area, and stromal area were higher at baseline in eyes with acute CSCR compared to healthy controls. Chronic CSCR eyes showed an increase in choroidal area and stromal area and a decrease in the luminal area at 15 min. There was a significant decrease in CVI at 30 and 45 min in chronic CSCR and CVI at 45 min in fellow eyes of acute CSCR. Repeated-measures analysis of variance (ANOVA) showed a significant change in central macular thickness in acute CSCR, choroidal thickness in fellow eyes of acute CSCR, stromal area, and total choroidal area in chronic CSCR. Mixed model ANOVA showed that the change in various choroidal parameters seen had no interaction with the eye type. Conclusion: Although change in various parameters was seen in acute CSCR, chronic CSCR, and fellow eyes of acute CSCR following WDT, the change was not significantly different among the groups.

Purpose To assess whether treatment of chronic central serous chorioretinopathy (cCSC) with photodynamic therapy (PDT) and high-density subthreshold micropulse laser (HSML) results in choroidal vascularity index (CVI) changes that may account for the treatment effect. Methods Patients with cCSC were prospectively included and analyzed. Patients received either half-dose PDT or HSML treatment. CVI of the affected and unaffected eye was obtained before treatment, 6 to 8 weeks after treatment, and 7 to 8 months after treatment. Results At baseline, 29 eyes (29 patients) were included both in the PDT and in the HSML group. The mean (± standard deviation) CVI change in the HSML group between before PDT and 6 to 8 weeks after PDT was − 0.009 ± 0.032 (p = 0.127), whereas this was 0.0025 ± 0.037 (p = 0.723) between the visit before PDT and final visit. The patients in the PDT group had a CVI change of − 0.0025 ± 0.037 (p = 0.723) between the visit before PDT and first visit after PDT, and a mean CVI change of − 0.013 ± 0.038 (p = 0.080) between the visit before PDT and final visit. There was no significant correlation between CVI and BCVA at the measured time points, in both the HSML group (p = 0.885), and in the PDT group (p = 0.904). Moreover, no significant changes in CVI occurred in the unaffected eye at any time point. Conclusions PDT and HSML do not significantly affect CVI, and therefore a CVI change may not be primarily responsible for the treatment effect. The positive treatment effect of both interventions may rely on other mechanisms, such as an effect on choriocapillaris and/or retinal pigment epithelium function.

Enhancement in vehicle technology system is getting increased research popularity and adding a vehicle theft security system in order to avoid getting vehicle theft in the parking and sometimes driving in unsecured places. The proposed system provided security and better theft control by using facial recognition and giving shock treatment, when the unauthorized person try to start the ignition and will be notified by the IOT application. The system uses Microprocessor raspberry pi along with a pie cam and a WIFI controller installed in the vehicle the implemented system is very simple with greater security for vehicle anti -theft protection and low cost technique compared to others.

Purpose: To evaluate the choroidal vascularity index of eyes for acute and chronic central serous chorioretinopathy patients using swept-source optical coherence tomography generated en-face scans. Methods: This was a retrospective study, in which slabs of en-face optical coherence tomography scans, at 5 μm intervals, spanning from the retina to choroid, were binarized using a validated algorithm to calculate choroidal vascularity index. The choroidal vascularity index was defined as the ratio between the choroidal vascular luminal area and the total choroidal area. Choroidal vascularity index was calculated for all the slabs of every subject in both the groups. Results: A total of 30 eyes for each acute and chronic central serous chorioretinopathy groups were recruited. The mean choroidal vascularity index of the acute group was 45.21% ± 2.25% at the choriocapillaris, which increased to the maximal value of 48.35% ± 2.06% at 75% depth of the choroidal thickness and 45.31% ± 3.27% at the choroidoscleral interface; whereas for the chronic group, the mean choroidal vascularity index was 44.76% ± 2.60% at the choriocapillaris, which maximized at 50% choroidal depth (48.70% ± 1.32%) and then returned to 45.41% ± 6.02% at the choroidoscleral interface. Conclusion: For both groups, the choroidal vascularity index increased from choriocapillaris to maximum values at mid-choroid and returned to almost the choriocapillaris value at the choroidoscleral interface.

The automatic segmentation of fluid spaces in optical coherence tomography (OCT) imaging facilitates clinically relevant quantification and monitoring of eye disorders over time. Eyes with florid disease are particularly challenging to segment, as the anatomy is often highly distorted from normal. In this context, we propose an end-to-end machine learning method consisting of near perfect detection of retinal fluid using random forest classifier and an efficient DeepLab algorithm for quantification and labeling of the target fluid compartments. In particular, we achieve an average Dice score of 86.23% with reference to manual delineations made by a trained expert.

Purpose. To analyse the vascular density of the choroid in a keratoconus (KC) population using swept-source optical coherence tomography (SS-OCT). Methods. Prospective, noninterventional study that analysed 97 eyes from 52 KC patients and 145 eyes from 89 healthy controls. The sample was divided in four different age groups. Inclusion criteria were topographic diagnosis of KC using Pentacam, axial length shorter than 26 mm, good quality of the images, and no other systemic or ocular diseases. A 12 mm horizontal single-line SS-OCT b-scan was performed to create a choroidal thickness (CT) profile. Validated automated segmentation and binarization were used in order to analyse choroidal, stromal, and vascular areas. Results. The percentage of choroidal vascularity (vascular area/total area) was 56.6% in KC patients vs. 49.4% in controls. Aged-adjusted choroidal, stromal, and vascular areas and corrected choroidal percentage of vascularity are statistically increased in KC patients when compared with healthy controls (p<0.001). All these parameters show a decreasing trend with age. Both stromal and vascular areas were thicker in KC patients (p<0.001). Conclusions. Choroidal, stromal, and vascular areas and corrected choroidal percentage of vascularity are statistically increased in KC patients when compared with healthy controls. All these parameters tend to decrease with age.

Purpose: The purpose of this study is to detect the optic nerve head (ONH) and peripapillary perfusion in eyes with acute nonarteritic anterior ischemic optic neuropathy (NAION) compared to the fellow normal eyes using optical coherence tomography angiography (OCTA) and to compare with nonischemic disc edema (papilledema). Methods: Retrospective analysis of patients with unilateral NAION who underwent OCTA was performed. All patients underwent comprehensive ocular examination including visual field testing. ONH was imaged using 6 mm × 6 mm scan by Topcon DRI Triton® OCT system. Vascularity loss was analyzed using ImageJ software in diseased eyes in comparison to normal fellow eyes and eyes with papilledema. Results: Twenty-one patients (15 males, 6 females) with unilateral NAION and 9 patients (18 eyes) with papilledema were included in the study. In eyes with NAION, two distinct patterns of loss of vasculature were noted – (a) diffuse loss of microvasculature cuff and vascular network around the optic disc in all the patients (100%) and (b) additional area of sectoral loss of vasculature extending from the disc in 12 of the 21 eyes (57.14%). All 18 eyes with papilledema showed loss of the microvasculature cuff; however, none showed the focal pattern of vascular defect. The mean area of the peripapillary vascular zone in eyes with NAION was significantly lesser than that in normals. Of the 12 eyes with NAION with focal loss of vasculature, 11 correlated with visual field defects (91.6%). Conclusion: Deficient peripapillary choroidal vasculature is present in NAION and has a different pattern than in nonischemic disc edema and can cause corresponding visual field deficits.

Purpose: To report the en-face choroidal vascularity index in healthy eyes. Methods: Thirty eyes of 30 healthy individuals were studied. Multiple high-density cross-sectional swept source optical coherence tomography scans were obtained to create a volume scan. The choroid was segmented for the whole volume scan and choroidal inner boundaries were flattened. Subsequently, multiple en-face scans separated by 25 µm were obtained and binarized. Choroidal vascularity index was calculated at level of choriocapillaris, medium, and large choroidal vessels. Results: The mean age of the study cohort was 35.6 ± 8.8 years. The overall mean en-face choroidal vascularity index was 54.25 ± 0.55%. There was a statistically significant difference of choroidal vascularity index in choriocapillaris (53.16 ± 0.43%), medium choroidal vessel (51.38 ± 0.27%), and large choroidal vessel (55.69 ± 0.87%) (p 400 µm) showed a statistically significant difference (p = 0.001). Choroidal vascularity index showed a significant correlation with subfoveal choroidal thickness (r = 0.441; p = 0.015), whereas there was no significant correlation of age (p = 0.21), refraction (p = 0.20), and gender (p = 0.67) with en-face choroidal vascularity index. Conclusion: En-face choroidal vascularity index shows a significant variation at the level of choriocapillaris, medium choroidal vessel, and large choroidal vessel in normal eyes. Choroidal vascularity index reaches a nadir at the level of medium choroidal vessel and reaches the maximum value at large choroidal vessel near choroidoscleral interface. En-face choroidal vascularity index shows a significant physiological variation and appears to increase with increase in subfoveal choroidal thickness.

Purpose To obtain a choroidal vascularity index (CVI) map of macular area on an Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Methods The study was a cross-sectional study involving 30 eyes of 30 healthy individuals. In brief, a shadow-compensated automated algorithm was used to segment and binarize the individual optical coherence tomography (OCT) B-scans. This was followed by three-dimensional reconstruction of these processed B-scans to obtain the overall thickness and vascularity maps. ETDRS grid was overlaid on both the extrapolated thickness and vascularity maps to obtain the corresponding sector-wise CVI. The main outcome measure was to evaluate the topographical variation of CVI in the macular area. Results The mean age of the study participants was 44.33 ± 16.29 years (range, 18-70 years). CVI showed no significant difference in different rings, subfields, or quadrants of the ETDRS map. CVI had a negative correlation with age (r = -0.384, P = 0.03). There were no statistically significant differences between CVI of both eyes in either rings or the full ETDRS grid (P = 0.30) among normal subjects. Conclusions The variation in CVI does not follow similar patterns as seen in choroidal thickness (CT) in various locations. The novel choroidal vascularity mapping in the macular area may expand understanding on regional differences of choroidal vasculature in healthy eyes.

Background: To map the choroidal vascularity index and compare two eyes in patients with unilateral central serous chorioretinopathy (CSCR). Methods: This was a retrospective, observational study performed in patients with unilateral CSCR. Choroidal thickness (CT) and Choroidal vascularity index (CVI) were measured and mapped in various zones according to the early treatment diabetic retinopathy (ETDRS) grid. Results: A total of 20 CSCR patients (20 study and 20 fellow eyes) were included in the study. Outer nasal region CT was seen to be significantly lower than central CT (p = 0.042) and inner nasal CT (p = 0.007), outer ring CT was significantly less than central (p = 0.04) and inner ring (p = 0.01) CT in CSCR eyes. On potting all the CVI values against the corresponding CT values, a positive correlation was seen in CSCR eyes (r = 0.54, p &lt, 0.01), which was slightly weaker in fellow eyes (r = 0.3, p &lt, 0.01) and a negative correlation was seen in healthy eyes (r = −0.262, p &lt, 0.01). Conclusions: Correlation between CVI and CT was altered in CSCR eyes as compared to fellow and normal eyes with increasing CVI towards the center of the macula and superiorly in CSCR eyes.

Background: Central serous chorioretinopathy (CSCR) is a chorioretinal disease affecting mostly middle age males. It is marked by the serous detachment of the neurosensory layer at the macula. This review of the literature provides a framework of the current characteristic/relevant imaging findings of CSCR. Although the pathogenesis of CSCR is unclear, the choroid plays a major role and its changes are fundamental to the diagnosis and treatment of CSCR. Methods: A systematic literature search focusing on current multimodal imaging for CSCR was performed. Only articles reporting on original clinical data were selected, studies in a language other than English were included only if an English abstract was provided. Additional sources included articles cited in the references list of the first selected articles. We deduced imaging findings based on current and relevant literature on the topic. Results: We found that sub foveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) were greater in eyes with acute CSCR than in eyes with chronic CSCR or normal eyes. There was increased choroidal thickness (CT) in the macula compared to peripapillary region. In healthy eyes, the highest CVI was found in the nasal region followed by the inferior, temporal, and superior quadrant. The area with the least CVI was the macula. In eyes with CSCR, 100% had asymmetric dominant vortex veins compared to 38% in normal eyes. Conclusion: Choroidal imaging has advanced the diagnosis of CSCR. This has led to numerous imaging biomarkers like CVI, CT, and hyper-reflective dots for early detection and possible prognostication of CSCR. More techniques like wide field scans and en face imaging are being employed to characterize the choroid in CSCR.

Purpose: To investigate choroidal hyper-reflective foci (HRF) in subjects with retinal dystrophy [Stargardt's disease (SGD) and retinitis pigmentosa (RP)] and their association with demographics, visual acuity, choroidal thickness (CT), and choroidal vascularity index (CVI). Methods: Single center retrospective study of subjects with previously diagnosed SGD or RP. Swept-source optical coherence tomography images were analyzed for the presence of choroidal HRFs and CVI using previously validated automated algorithm. A Spearman's rank correlation coefficient was used to evaluate the correlation between the number of HRF and various baseline parameters including age, visual acuity, intraocular pressure, and other optical coherence tomography (OCT) parameters (CT, choroidal area, and CVI) were evaluated in these subjects. Results: This study included 46 eyes (23 subjects) and 55 eyes (28 subjects) with previously diagnosed RP and SGD, respectively. In the RP group, the mean number of HRFs was 247.9 ± 57.1 and mean CVI was 0.56 ± 0.04. In SGD group, mean HRF was 192.5 ± 44.3 and mean CVI was 0.41 ± 0.04. Mean HRF was significantly greater in the RP group (0.02), however, the mean CVI was not statistically different. In RP, mean HRF were correlated only with CVI (r = 0.49; P = 0.001), however, in SGD, it correlated with only choroidal area (r = 0.27; P = 0.04). Conclusion: Choroidal HRF were present in both RP and SGD subjects with more HRFs in those with RP. These HRFs were associated with alteration in choroidal vascularity, which further adds into the pathogenesis of these diseases.

To report variation of choroidal vascularity index (CVI) in macular and mid-equator areas in healthy subjects using wide-field optical coherence tomography (WF-OCT).Prospective, cross-sectional study.Setting: Two-center study.Twenty eyes of 20 healthy subjects.Single high-definition scans passing through the fovea in both vertical and horizontal meridians were studied. Images were taken in primary gaze and extremes of gaze and a manual montage was created. A previously reported semi-automated algorithm was used to calculate the CVI in macular, superior, inferior, temporal, and nasal quadrants.Difference in CVI in macular area and 4 quadrants.Twenty eyes from 20 subjects were enrolled in the study. The mean age was 28.85 ± 6.29 years with men comprising 9 of the 20 subjects (45.0%). The refractive error (spherical equivalent) ranged from -3.00 to +0.75 diopters. The average CVI in the macular area (40.01 ± 7.67) was significantly smaller than in any of the other fundus areas (all P.01). The maximum CVI was seen in the nasal quadrant (50.84 ± 5.64), followed by inferior (47.93 ± 9.31), temporal (46.14 ± 7.06), and superior (45.72 ± 7.69). The nasal quadrant was found to have the least coefficient of variation (CV) of CVI (0.11) while the inferior and macular area had the highest CV (0.19).We report CVI in WF-OCT in healthy young individuals. CVI seems to have a wide topographic variation. The macular area had the least CVI. CVI values are more consistent with lesser CV in the nasal quadrant compared to the other quadrants and macular area.

The introduction of wide field optical coherence tomography (WF-OCT) has provided newer insights in the imaging of peripheral choroid. We evaluated choroidal thickness (CT) and large choroidal vessel thickness (LCVT) of 20 eyes in horizontal and vertical meridians using WF-OCT. A high-definition line scan through the fovea in both horizontal and vertical meridian was captured in primary and extremes of gaze to obtain scans up to mid-equator. CT and LCVT measurements were done across predefined points in macular area and all quadrants. LCVT was calculated after identifying a large choroidal vessel near choroidoscleral interface. The main outcome measures were differences in CT and LCVT in macular and four quadrants. Mean CT (331.23 ± 76.34 µ) and LCVT (201.46 ± 54.31 µ) in vertical macular segment were significantly more than CT (245.79 ± 55.38 µ; p = 0.0002) and LCVT (150.48 ± 52.58 µ; p = 0.004) in horizontal macular segment. CT at peripheral points in all quadrants was significantly reduced as compared to subfoveal CT (all p values

BACKGROUND AND OBJECTIVE: Choroidal vascularity index (CVI) is a noninvasive tool to assess choroidal structure. The objective of the current study was to compare the CVI measurements on swept-source optical coherence tomography (SS-OCT) and spectral-domain OCT (SD-OCT) scans using the same image binarization protocol. PATIENTS AND METHODS: This prospective study was conducted from July 2016 through January 2017 and involved 54 healthy volunteers at a tertiary referral eye care institute in Southern India. Choroidal scans were obtained using both SS- and SD-OCT machines. An automated binarization algorithm was used to compute CVI. RESULTS: The mean CVI with SS-OCT scans was 53.88% ± 12.54% (range: 20.46% to 73.93%), whereas the mean CVI with SD-OCT scans was 51.11% ± 7.97% (range: 29.90% to 67.72%)(P < .001). The unadjusted (95% confidence interval [CI], 0.554–0.851) and adjusted (95% CI, 0.607–0.871) intraclass correlation (ICC) estimates were quite similar and indicate moderate-to-good reliability of measurements by two machines. The interval estimate for a conversion factor between SD-OCT and SS-OCT can be calculated as follows: SD = [0.383*SS+19.467, 0.586*SS+30.661]. CONCLUSION: CVI is a noninvasive, robust, and reliable measurement of choroidal vascularity and CVI measurements obtained using both SS-OCT and SD-OCT concur with each other. [ Ophthalmic Surg Lasers Imaging Retina. 2019;50:e26–e32.]

Purpose: To report the diurnal variation in choroidal vascularity index (CVI) in subfoveal (SF-CVI) and peripapillary area in healthy eyes. Methods: The study was a cross-sectional study including 12 healthy subjects. Swept-source optical coherence tomography scans were taken at 9 am, 11 am, 1 pm, 3 pm, and 5 pm. Subfoveal choroidal thickness (SFCT) and CVI were calculated using automated segmentation techniques and previously validated algorithms. Systemic parameters including systolic blood pressure (SBP), diastolic blood pressure, mean arterial pressure, and mean ocular perfusion pressure were calculated and correlated with SFCT and CVI. Results: A total of 12 eyes (right eye) of 12 patients (mean age: 26 ± 3.77 years) were analyzed. The mean (±standard deviation) amplitude of SFCT and SF-CVI variation was 35.91 ± 14.8 μm (range, 15–69 μm) and 0.05 ± 0.02 (range, 0.02–0.08). The mean CVI showed a significant diurnal variation in the temporal quadrant of the peripapillary region (P = 0.02). Conclusion: SFCT and SF-CVI showed a significant diurnal variation in amplitude (peak–trough analysis) and SF-CVI correlated well with SBP suggestive of a direct influence of blood pressure on choroidal vascularity. The mean peripapillary CVI in the temporal quadrant also showed a significant diurnal variation with no significant change in other quadrants.

A concise and simple synthesis of M1 allosteric agonist 1-(1′-(2-methylbenzyl)-1,4′-bipiperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one (TBPB) using economical and commercially available orthophenylenediamine (O-PDA) and Boc piperidone has been described. The disclosed scheme allows synthesizing more analogs that were otherwise difficult to prepare with the original method. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Objective To develop an algorithm for automated quantification of Haller’s layer in choroid using swept-source optical coherence tomography (OCT). Background So far, to understand the association of various diseases with structural changes of choroid, only gross indicators such as thickness, volume and vascularity index have been examined. However, certain diseases affect specific sublayers of the choroid. Accordingly, a need for targeted quantitation arises. In particular, there is significant interest in understanding Haller’s layer, a choroidal sublayer comprising relatively large blood vessels. Unfortunately, its intricate vasculature makes, manual quantitation difficult, tedious, and error-prone. To surmount this difficulty, it is imperative to develop an algorithmic method. Methodology The primary contribution of this work consists in developing an approach for detecting the boundary between Haller’s and Sattler’s layers, the latter comprising medium-sized vessels. The proposed algorithm estimates vessel cross-sections using exponentiation-based binarization, and labels a vessel large if its cross-section exceeds certain statistically determined threshold. Finally, the desired boundary is obtained as a smooth curve joining the innermost points of such large vessels. On 50 OCT B-scans (of 50 healthy eyes), our algorithm was validated both qualitatively and quantitatively, by comparing with intra-observer variability. Extensive statistical analysis was performed using metrics including Dice coefficient (DC), correlation coefficient (CC) and absolute difference (AD). Results The proposed algorithm achieved a mean DC of 89.48% (SD:5.03%) in close agreement with the intra-observer repeatability of 89.12% (SD:5.68%). Corresponding mean AD and mean CC were of 17.54 μm (SD:16.45μm) and 98.10% (SD:1.60%) which too approximate the respective intra-observer repeatability values 19.19 μm (SD:17.69 μm) and 98.58% (SD:1.12%). Conclusion High correlation between algorithmic and manual delineations indicates suitability of our algorithm for clinically analyzing choroid in greater finer details, especially, in diseased eyes.

Purpose: To compare the accuracy of manual and automated binarization technique for the analysis of choroidal vasculature. Methods: This retrospective study was performed on a total of 98 eyes of 60 healthy subjects. Fovea-centered swept source optical coherence tomography (SS-OCT) scans were obtained and choroidal area was binarized using manual and automated image binarization technique separately. Choroidal vessel visualization in the binarized scans were subjectively graded (grades 0–100) by comparing them with the original OCT scan images by two masked graders. The subjective variability and repeatability was compared between two binarization method groups. Intergrader and intragrader variability was estimated using paired t-test. The degree of agreement between the grades for each observer and between the observers was evaluated using Bland–Altman plot. Results: The mean accuracy grades of the automatically binarized images were significantly (P < 0.001) higher (93.38% ± 1.70%) than that of manually binarized images (78.06% ± 2.92%). There was a statistically significant variability and poor agreement between the mean interobserver grades in the manual binarization arm. Conclusion: Automated image binarization technique is faster and appears to be more accurate in comparison to the manual method.

Purpose: This study aims to compare the effect of laser photocoagulation or observation on choroidal vascularity in acute central serous chorioretinopathy (CSCR). Methods: A retrospective analysis of 30 patients with acute CSCR treated either with laser photocoagulation (16 eyes) or sham laser (14 eyes) was performed. Demographic details, visual acuity (VA) assessment, and other relevant clinical data were considered from baseline to the 3rd and 6th month follow-up visits. Participants with chronic CSCR and missing follow-up or inadequate data were excluded. Choroidal analysis including choroidal thickness and choroidal vascularity index (CVI) assessment was done for each visit using Spectral Domain (SD) Optical Coherence Tomography (OCT) images. Results: In laser arm group, there was a statistically significant change in VA, contrast sensitivity and central macular thickness (CMT) and neurosensory detachment (NSD) (P < 0.05) at the 3rd and 6th month visits. However, there was no statistically significant difference in subfoveal choroidal thickens (SFCT) and CVI (P > 0.05) at both the visits. In sham laser group, similarly, there was a significant improvement in VA, contrast sensitivity, CMT, and CVI (P < 0.05) at the 3rd and 6th month visits. There was significant reduction in NSD at the 3rd month; however, it was not statistically significant at the 6th month visit. SFCT did not change significantly at both the visits. There was no significant difference for the changes in parameters between the groups at the 6th month. Regression analysis showed no significant correlation with final VA with any of the baseline parameters. Conclusion: Early laser photocoagulation does lead to change in choroidal morphology, though insignificant, in comparison to observation. The present data, yet again, support no additional benefit of early laser photocoagulation in acute CSCR.

Various novel cyclophane amides with a large cavity have been synthesized. The structures of cyclophane amides 14 and 15 were resolved using XRD studies. Cyclophane amide 28 shows a shift in λmax in the UV/Vis. spectra when treated with Cu (II) ion as well as with Pb (II) ion. Ion transportation studies were carried out with cyclophane amide 14 which proved that the Na+ ion passes through the cavity while K+ ions are retained.

Catalytic amounts of VO(acac)2 coupled with t-butylhydroperoxide chemoselectively oxidizes thiols to disulfides under mild reaction conditions and is generally useful for a wide variety of thiols. *IICT communication No. 4400.