Optical diffraction properties of three superimposed self-organized nanostructures induced by a laser process.

Controlling the diffraction properties of materials over a large area holds great promise for a wide range of optical applications. Laser-based techniques have emerged as a viable solution to address this need. Here, we present the diffraction properties of laser-induced self-organized structures, which consist of three interlaced grating-like structures: self-organized nanoparticles, self-organized cracks, and laser marking lines. Under normal incidence external illumination, the sample exhibits an asymmetric diffraction pattern. However, when the incidence angle is tilted, circular diffraction patterns are observed in the plane perpendicular to both the sample and the incidence plane. These phenomena are attributed to the combination effect of the diffraction gratings. To elucidate the underlying physics of multiple diffraction, we use rigorous coupled-wave analysis (RCWA) and grating equations written in direction cosine space, extended to account for the presence of three superimposed gratings. Exploiting the laser-induced diffraction properties of these samples may have great potential for various industrial implementations, including security, display, and design.

Hybridization between plasmonic and photonic modes in laser-induced self-organized quasi-random plasmonic metasurfaces.

Plasmonic metasurfaces made of perfectly regular 2D lattices of metallic nanoparticles deposited on surfaces or close to waveguides can exhibit hybridized plasmonic and photonic modes. The latter arise from the excitation of surface or guided modes through the in-plane coherent scattering of periodic arrays. Recently, laser-induced self-organization of random plasmonic metasurfaces has been used to create nanoparticle gratings embedded in protective layers. Despite the broad size distribution and positional disorder of nanoparticles, the resulting nanostructures exhibit strong coupling between plasmonic and photonic modes in transverse electric polarization, leading to dichroism, which is well-reproduced from one laser printing to another. Here, we examine quantitatively the effect of inhomogeneities at the nanoscale on the hybridization between localized plasmonic modes and delocalized guided modes by considering realistic laser-induced self-organized nanoparticle arrays embedded in a two-layer system. By referring to regular samples, we describe the optical mechanisms involved in the hybridization process at characteristic wavelengths, based on far and near field simulations. Two kinds of real samples are considered, featuring different levels of coupling between the plasmonic and photonic modes. The results demonstrate that controlling the statistical properties of plasmonic metasurfaces, such as the nanoparticle size distribution and average position, over areas a few micrometers wide is enough to control in a reproducible manner the hybridization mechanisms and their resulting optical properties. Thus, this study shows that the inherent irregularities of laser-induced self-organized nanostructures are compatible with smart functionalities of nanophotonics, and confirms that laser processing has huge potential for real-world applications.

Anti-Counterfeiting White Light Printed Image Multiplexing by Fast Nanosecond Laser Processing.

Passive plasmonic metasurfaces enable image multiplexing by displaying different images when altering the conditions of observation. Under white light, three-image multiplexing with polarization-selective switching has been recently demonstrated using femtosecond-laser-processed random plasmonic metasurfaces. Here, the implementation of image multiplexing is extended, thanks to a color-search algorithm, to various observation modes compatible with naked-eye observation under incoherent white light and to four-image multiplexing under polarized light. The laser-processed random plasmonic metasurfaces enabling image multiplexing exhibit self-organized patterns that can diffract light or induce dichroism through hybridization between the localized surface plasmon resonance of metallic nanoparticles and a lattice resonance. Improved spatial resolution makes the image quality compatible with commercial use in secured documents as well as the processing time and cost thanks to the use of a nanosecond laser. This high-speed and flexible laser process, based on energy-efficient nanoparticle reshaping and self-organization, produces centimeter-scale customized tamper-proof images at low cost, which can serve as overt security features.

Using 320-detector row computed tomography angiography to investigate the arterial anatomy of the toe flaps on living humans.

PURPOSE: Using 320-detector row computed tomography angiography (320-CTA) to investigate the arterial supply for the toe flaps, namely the anatomical characteristics of the dorsalis pedis artery (DPA), the first dorsal metatarsal artery (FDMA), and the arteries of the first toe web space (AsFTWS). METHODS: This was a prospective study on CTA of 72 intact feet of 36 Vietnamese adults who had sequelae of thumb or metacarpal hand amputation, from June 2017 to December 2019, then preoperative CTA images were compared with surgical findings on 31 feet of 29 patients. RESULTS: 320-CTA was able to investigate the DPA, FDMA, and AsFTWS in 100% of cases. DPA was absent in 6.9% of cases. The average diameters at its origin and termination were 3.22 and 2.56 mm, respectively. For FDMA, the rates of Gilbert type I, II, and III were 52.8%, 18.1%, and 29.2%; the average diameters at its origin and termination were 1.98 and 1.67 mm, respectively. At the first toe web space, FDMA was dominant in 54.2% of cases; the first plantar metatarsal artery (FPMA) was dominant in 29.2% of cases; both arteries were equally dominant in 16.6%. The average diameter at the origin of the lateral plantar digital artery of the great toe was 1.48 mm, of the medial plantar digital artery of the second toe was 1.21 mm. Preoperative CTA images resembled the surgical findings in all cases. The survival rate of toe flaps was 100%. CONCLUSION: The 320-CTA provided proper preoperative images in two and three dimensions, and helped surgeons to establish a preoperative surgical plan, thus increasing the success rate of toe transfer surgery.

Complications and functional, psychological outcomes of bilateral tibial lengthening over intramedullary nail: evidence from Vietnam.

BACKGROUND: The purpose of this study was to assess the functional, psychological outcomes and complications of bilateral tibial lengthening over intramedullary nail. The intramedullary nail in this study was the Surgical Implant Generation Network (SIGN) nail. MATERIAL AND METHODS: We enrolled patients desiring stature lengthening at the 108 Military Central Hospital (Hanoi, Vietnam) from October 2011 to January 2019. A total of 104 people have been enrolled in the study and underwent the bilateral tibial lengthening procedure. RESULTS: Average tibial lengthening was 7.1 ± 0.8 cm in men and 6.5 ± 0.6 cm in women. Percentage of tibial lengthening as compared with tibia length at the time of pre-operation was 23.9 ± 3.5% for male patients and 21.5 ± 3.7% for female patients. The outcome was excellent in 85 patients (81.7%) and good in 19 (18.3%). All patients experienced improved self-esteem and enhanced quality of life. CONCLUSION: Our study suggests that bilateral tibial lengthening over nail was safe and effective provided complications are looked for and kept in check. Equinus contracture, pin tract infection, and valgus deviation were the most common complications. Valgus deviation occurs during distraction period. In patient who had neutral or valgus alignment, we recommend to use a blocking screw at the proximal segment post-operatively and use a blocking screw at the valgus distal segment at the end of distraction period to maintain the mechanical axis of both tibias. Bilateral tibial lengthening over nail should be widely employed in low-income countries.

Use of single-staged transmetatarsal trimmed great toe transfer for reconstruction of a thumb amputation at the carpometacarpal joint.

BACKGROUND: Reconstruction for proximal thumb amputation at the carpometacarpal (CMC) joint level is extremely challenging. All thenar muscles are lost and other fingers might be lost or injured. Transmetatarsal trimmed great toe (TGT) transfer may be an option in such cases. METHODS: Between 2012 and 2018, 11 patients who had amputation of the thumb at the CMC joint level were reconstructed by transmetatarsal TGT transfer in a single stage. There were seven cases in which the right hand was affected and four cases in which the left hand was affected. Three cases involved a contracture scar at the thumb stump and required web space reconstruction. Average follow-up was 33.9 months (range: 12-76 months) RESULTS: All toe transfers survived. The average of static two-point discrimination (S2PD) was 14.6 mm; the average scores of the Quick Disabilities of the Arm, Shoulder, and Hand (quickDASH) questionnaire and the Michigan Hand Outcomes Questionnaire (MHQ) were 18.6 and 73.8, respectively. Two cases did not achieve opposition due to mispositioning of the neothumb. In nine cases achieving opposition, the Kapandji score ranged from 4 to 9, pinch ranged from 3 to 11 lbs, and grip ranged from 15 to 86 lbs. In the donor foot, three patients had neuroma and two had a new callus on the palmar side of the second and third metatarsal heads. The average foot and ankle disability index score was 91.6. CONCLUSION: Single-staged transmetatarsal TGT transfer is safe and useful for thumb reconstruction at the CMC joint level. This reconstructive method is suitable for manual workers, especially in the developing countries.

A simple approach to thumb amputation reconstruction at metacarpal base with toe transfer, two case reports.

INTRODUCTION: Reconstruction for thumb amputation at the metacarpal base by toe transfer is challenging. To restore a thumb with normal or near-normal length, the reconstruction plan usually involves a complicated and challenging process either in two stages (stage 1: resolving soft tissue and bone defect; stage 2: toe transfer) or a single stage by using two free flaps (one free soft tissue flap and one toe flap). However, is it necessary to restore the full length of the thumb for functional and aesthetic achievement? PRESENTATION OF CASES: Two male patients (21 and 22 years old) had a thumb amputation at the metacarpal base. We accepted the shortened metacarpal length and performed reconstruction in one stage by trimmed great toe flap, at the level of the metatarsophalangeal joint. The first phalanx of toe flap was fused with the first metacarpal base. On long-term follow-up, both patients were able to return to daily activities, work and had a good cosmesis. DISCUSSION: With our reconstruction technique, two reconstructed thumbs were functionally similar to a thumb amputation group 1 of Campbell-Reid. Using trimmed great toe flap, the tip of our reconstructed thumbs looks like that of a normal thumb. Both patients were satisfied. CONCLUSION: Accepting length shortening, the reconstruction for thumb amputation at the metacarpal base by toe transfer could be done more easily and simply in a single stage.

Cardiopulmonary Exercise Testing in Aortic Stenosis.

Patients with moderate to severe aortic stenosis (AVA <1.3 cm2) who were judged, by a referring cardiologist, as asymptomatic or equivocal symptomatic from the aortic stenosis were included in the study. Patients with left ventricular ejection fraction <50% were not included. Twenty-nine percent of the referred patients were judged asymptomatic and 71% equivocal symptomatic from their valve disease. The mean age was 72 years and 90% of the patients had an AVA-index <0.6 cm2/m2. By clinical evaluation in the outpatient clinic, 48% were judged as having functional limitation corresponding to NYHA≥II. The study participants had cardiopulmonary exercise testing (CPX) at inclusion, and, if relevant, pre- and nine months post-aortic valve replacement (AVR). CPX was feasible in 130 of 131 study participants recruited across 19 months. The coefficient of variability by test-retest was 5.4% and 4.6% for peak oxygen consumption (pVO2) and peak oxygen pulse (pO2pulse= pVO2/peak heart rate), respectively. The stroke volume generally increased with exercise, also in those with peak flow velocity across the aortic valve (Vmax) >5 m/s, >4 m/s, and <4 m/s but with high valvuloarterial impedance (Zva >5.5 mm Hg/(mL·m2 )). This was found both when assessed by inert gas rebreathing and by the pO2pulse/hemoglobin index. Both resting and exercise stroke volume were lower for the latter group, with Vmax <4 m/s but high valvuloarterial impedance. A pVO2 <83% of the predicted, which corresponds to the lower 95% percentile found in the healthy sedentary population, was predicted independently by lower stroke volume during exercise, lower heart rate during exercise, lower FEV1, and by higher ventilation/carbon dioxide exhaustion rate (VE/VCO2), but not by the severity of the aortic stenosis as determined by echocardiography. According to the CPX results, the patients were prospectively grouped into 3 groups, as follows: 1) normal pVO2 (>83% of predicted) and pO2pulse (>95% of predicted); 2) subnormal pVO2 or pO2pulse that according to CPX could be explained by causes other than hemodynamic compromise; 3) subnormal pVO2 and pO2pulse. Groups 1 and 2 followed an initial conservative strategy, whereas Group 3 was referred for angiogram and Heart Team evaluation for AVR. The patients were followed for an average of 24 months and, in Groups 1 and 2, one patient (0.9%) suffered cardiac death and seven were hospitalized with heart failure (6.7%). The patient who died and another patient with heart failure had both previously, during the study, declined AVR. For Groups 1 and 2, the rate of the combined endpoint progression to cardiac death, hospitalization with heart failure, or AVR was 37.5%, which seems lower than what was reported in the literature by conventional assessment and strategy for younger asymptomatic patients with comparable echocardiographic severity of aortic stenosis. The endpoint progression to cardiac death, hospitalization with heart failure, or AVR with improvement in pVO2 or in the Physical Component Score of the SF-36 health-related quality of life score was reached in 25.6% in Groups 1+2 and in 62.5% in Group 3 (p=0.003). A decreased pO2pulse, which expresses stroke volume at peak exercise, predicted this endpoint. In 73 operated patients without left ventricular dysfunction and no coronary stenosis, including 37 patients from the above-mentioned study, a CPX 9 months post-AVR showed that the pVO2, on average, was less than that predicted (mean 89% of the predicted ) and 35% of the patients had a subnormal pVO2 (<83% of that predicted). A preoperative mean gradient <40 mm Hg across the aortic valve, the presence of atrial fibrillation, and a permanent pacemaker post-AVR all predicted a post-AVR pVO2 <83% of that predicted. For the 37 patients with a pre-AVR CPX, a postoperative decrease >10% in the absolute pVO2 was noted in 30% and an increase >10% in 24% of patients. A decrease >10% in pVO2 was predicted by preoperative mean gradient <40 mm Hg and an increase in pVO2 was predicted by preoperative AVAI <0.4 cm2/m2 and preoperative pO2pulse

Observed change in peak oxygen consumption after aortic valve replacement and its predictors.

OBJECTIVE: To assess the change in peak oxygen consumption (pVO2) and determine its outcome predictors after aortic valve replacement (AVR) for aortic stenosis (AS). METHODS: Patients with AS and preserved left ventricular ejection fraction who were referred for single AVR had cardiopulmonary exercise testing prior to and 9 months post-AVR. Predictors of outcome for pVO2 were determined by multivariate linear and logistic regression analyses. A significant change in pVO2 was defined as a relative change that was more than twice the coefficient of repeatability by test-retest (>10%). RESULTS: The pre-AVR characteristics of the 37 study patients included the following: median age (range) 72 (46-83) years, aortic valve area index (AVAI) 0.41 (SD 0.11) cm(2)/m(2), mean gradient (MG) 49.1 (SD 15.3) mm Hg and New York Heart Association (NYHA)≥II 27 (73%). Pre-AVR and post-AVR mean pVO2 was 18.5 and 18.4 mL/kg/m(2) (87% of the predicted), respectively, but the change from pre-AVR was heterogeneous. The relative change in pVO2 was positively associated with the preoperative MG (ß=0.50, p=0.001) and negatively associated with brain natriuretic peptide > upper level of normal according to age and gender (ß=-0.40, p=0.009). A relative increase in pVO2 exceeding 10% was found in 9 (24%), predicted by lower pre-AVR AVAI (OR 0.18; 95% CI 0.04 to 0.82, p=0.027) and lower peak O2 pulse (OR 0.94; 95% CI 0.88 to 0.99, p=0.045). Decreases in pVO2 exceeding 10% were found in 11 (30%) and predicted by lower MG (OR 0.93; 95% CI 0.86 to 0.99, p=0.033). CONCLUSIONS: Change in pVO2 was heterogeneous. Predictors of favourable and unfavourable outcomes for pVO2 were identified.