UV Irradiation of Polyethylene Terephthalate and Polypropylene and Detection of Formed Microplastic Particles Down to 1†µm.

The degradation of plastics upon UVC irradiation in aqueous solution and the formation of microplastic (MP) particles were investigated. Polypropylene (PP) and recycled and virgin polyethylene terephthalate (PET) were irradiated with a UV lamp emitting light at 254 nm. Irradiation was performed for 15 and 30 min, respectively, at an intensity of about 0.3 W cm-2 . The formation of MP was studied by Raman spectroscopy. The results showed that MP particles were formed after irradiation and that their number was significantly higher in the recycled PET than in the virgin material. The number of PP MP formed was lower compared to PET and was not significantly different after 15 and 30 min. In addition, ethanol was used as an alternative solvent to investigate how its chemical properties and interactions with UVC irradiation affect the degradation of PET and PP plastics. The use of ethanol and recycled PET resulted in a lower number of MP particles at both irradiation times. When ethanol was used after 30 min of irradiation, significantly more PP MP formed. The different chemical structures of PET and PP combined with the different solvent properties of water and ethanol contribute to the differences in their susceptibility to UVC degradation.

The Effect of Femtosecond Laser Irradiation and Plasmon Field on the Degree of Conversion of a UDMA-TEGDMA Copolymer Nanocomposite Doped with Gold Nanorods.

In this work, the effects of femtosecond laser irradiation and doping with plasmonic gold nanorods on the degree of conversion (DC) of a urethane dimethacrylate (UDMA)-triethylene glycol dimethacrylate (TEGDMA) nanocomposite were investigated. The UDMA-TEGDMA photopolymer was prepared in a 3:1 weight ratio and doped with dodecanethiol- (DDT) capped gold nanorods of 25 × 75 or 25 × 85 nm nominal diameter and length. It was found that the presence of the gold nanorods alone (without direct plasmonic excitation) can increase the DC of the photopolymer by 6-15%. This increase was found to be similar to what could be achieved with a control heat treatment of 30 min at 180 °C. It was also shown that femtosecond laser impulses (795 nm, 5 mJ pulse energy, 50 fs pulse length, 2.83 Jcm-2 fluence), applied after the photopolymerization under a standard dental curing lamp, can cause a 2-7% increase in the DC of undoped samples, even after thermal pre-treatment. The best DC values (12-15% increase) were obtained with combined nanorod doping and subsequent laser irradiation close to the plasmon resonance peak of the nanorods (760-800 nm), which proves that the excited plasmon field can directly facilitate double bond breakage (without thermoplasmonic effects due to the short pulse length) and increase the crosslink density independently from the initial photopolymerization process.

Biomechanical comparison of two InternalBrace™ reinforced thumb ulnar collateral ligament reconstruction techniques.

BACKGROUND: Chronic ulnar collateral ligament ruptures of the thumb metacarpophalangeal joint are often not eligible for direct surgical repair and ligament reconstruction could be considered. Several reconstruction techniques are published, with different types of configurations and fixation methods of the tendon grafts. However, failure of the reconstruction with recurrent instability is still a problem, despite stable graft to bone fixation. Augmentation of the free tendon graft with non-resorbable suture material is gaining popularity, aiming to withstand elongation or rupture of the graft. The purpose of this study was to compare two different augmented ulnar collateral ligament reconstruction methods in a cadaver model. METHODS: Ten matched pairs of cadaveric upper extremities were used. The thumbs were disarticulated at the trapezometacarpal joint and the ulnar collateral ligament was excised then reconstructed with InternalBrace™ reinforced tendon graft, which was fixed to the bones using either a Tenodesis screw or DX Swivelock® anchor. The thumbs were biomechanically tested with valgus stress, while the force and displacement were simultaneously measured and plotted. FINDINGS: The mean (SD) load at clinical failure and maximum load were 19.4 (5.3) and 31.4 (9.5) N in the Tenodesis group, and 21.0 (10.0) and 31.4 (13.9) N in the DX SwiveLock® group, respectively. None of these differences were significant. These results are comparable with previous publications. INTERPRETATION: The Tenodesis screw and the DX SwiveLock® thumb ulnar collateral ligament reconstruction with InternalBrace™ reinforced free tendon graft showed equal strength, both methods are feasible alternatives in the clinical setting.

Comparison of Glyphosate Detection by Surface-Enhanced Raman Spectroscopy Using Gold and Silver Nanoparticles at Different Laser Excitations.

Glyphosate is one of the most widely used pesticides in the world, but it has been shown to persist in the environment and therefore needs to be detected in food. In this work, the detection of glyphosate by surface-enhanced Raman scattering (SERS) using gold and silver nanoparticles and three different commonly used laser excitations (532, 632, and 785 nm wavelengths) of a Raman microscope complemented with a portable Raman spectrometer with 785 nm excitation is compared. The silver and gold nanosphere SERS substrates were prepared by chemical synthesis. In addition, colorimetric detection of glyphosate using cysteamine-modified gold and silver nanoparticles was also tested. The best results were obtained with Ag NPs at 532 nm excitation with a detection limit of 1 mM and with Au nanoparticles at 785 nm excitation with a detection limit of 100 µM. The SERS spectra of glyphosate with cysteamine-modified silver NPs improved the detection limits by two orders of magnitude for 532 nm excitation, i.e., up to 10 µM, and by one order of magnitude for 632 and 785 nm excitation wavelengths.

Biomechanical Comparison of Modified Adams-Berger and DX technique in DRUJ Reconstruction.

Background Adams-Berger ligamentoplasty is a widely accepted reconstruction for unrepairable triangular fibrocartilage complex (TFCC) injuries with instability. Failure of the reconstruction and recurrent instability is still a clinical problem. Internal brace augmentation of tendon grafts is gaining more popularity, but use in the distal radioulnar joint (DRUJ) is not yet published. Questions/Purposes The purpose of this study was to compare a novel anatomical DRUJ reconstruction with a modified Adams-Berger reconstruction to answer which technique stabilize better the DRUJ and which has enough stabilizing effect to allow early mobilization. Methods Nine matched pairs of cadaveric upper extremities were used. The dorsopalmar translations in the DRUJ that occurred with 50 N load were measured before and after detachment of the TFCC from the ulna and after ligament reconstruction with either modified Adams-Berger procedure or DX Swivelock technique. Internal brace augmented palmaris longus tendon grafts were used in all reconstruction. Results In the Adams-Berger group, the injured and the reconstructed displacements were significantly higher than the native, while in the DX group both the native and the reconstructed displacements were significantly lower than the injured. The mean (standard deviation) change of translations was 0.46 (1.94) mm after Adams-Berger and 2.51 (1.31) mm after DX reconstruction, implying significant better stabilizing effect of the latter. Conclusions DX Swivelock reconstruction showed better time zero stabilizing effect compared with Adams-Berger procedure, regaining almost normal stability of the DRUJ.

Arthroscopic Assisted Reconstruction of LT-Ligament: A Description of a New Technique.

Background Injuries of the lunotrirquetral ligament (LT lig) could be part of an extensive carpal injury and are then often treated at the time of the injury. However, when an injury of the LT ligament occurs alone, the injury is often missed. Treatment of this injury has traditionally been by open surgery, such as reattachment of the LT ligament, ligament reconstruction, or arthrodesis of the LT joint. These procedures needed a large exposure to the carpus running the risk of damaging the external ligaments, the nerves important for proprioception, and the capsule with the potential of scarring and adhesions. Materials and Methods We describe a novel arthroscopic assisted technique for reconstruction of the LT ligament. Using this less invasive technique, there is a possible advantage of lesser scarring and faster mobilization. Results We have performed this technique in two patients with more than 30 months follow-up. They both have great improvement of the functional scores. Conclusion The novel arthroscopic assisted technique for LT lig reconstruction is a technically demanding procedure; however, this obtains good clinical results with more than 30 months follow-up due to less exposure of the carpus. Level of Evidence This is a Level IV, case series study.

Preparation and Characterization of Perforated SERS Active Array for Particle Trapping and Sensitive Molecular Analysis.

A gold-coated array of flow-through inverse pyramids applicable as substrate for entrapment and immobilization of micro-objects and for surface enhanced Raman spectroscopic measurements was fabricated using bulk micromachining techniques from silicon. Surface morphology, optical reflectance, immobilization properties, and surface enhanced Raman amplification of the array were modelled and characterized. It was found that the special perforated periodic 3D structure can be used for parallel particle and cell trapping and highly sensitive molecular analysis of the immobilized objects.

The effect of adding active flexion to modified Kleinert regime on outcomes for zone 1 to 3 flexor tendon repairs. A prospective randomized trial.

In a prospective randomized study, we studied whether adding active flexion to a modified Kleinert regime changed outcomes of flexor tendon repairs in zone 1, 2 and 3 in 73 fingers (53 patients). Evaluation included active range of finger motion, grip and pinch strengths. Twelve months after surgery, the increase in range of active finger motion after adding active flexion was insignificant compared with that with the modified Kleinert regime. According to the Strickland criteria, 20 out of 29 fingers had excellent or good recovery after adding active flexion, as did 28 out of 34 fingers with the modified Kleinert regime; we could not detect significant improvement of the good and excellent rate. At 6 months, the pinch strength was significantly higher with the addition of active flexion. We failed to find that adding active finger flexion to the modified Kleinert regime improves the overall long-term results of repairs in zone 1 to 3, though recovery appeared faster, and the good and excellent recovery of zone 2 repairs was 17% greater with the active flexion protocol. LEVEL OF EVIDENCE: I.

Anatomic double-bundle reconstruction with free tendon graft for chronic ulnar instability of the thumb metacarpophalangeal joint.

Failed primary treatment of thumb metacarpophalangeal ligament injuries may lead to chronic instability. Different treatments have been described such as secondary ligament suture, fusion, dynamic or static procedures. Techniques to restrain the joint stability with various grafts of different configurations have been published, but most of these address only the proper collateral ligament. Experimental data revealed the importance of the accessory collateral ligament in stabilizing the metacarpophalangeal joint. In a former, true anatomic ligament reconstruction a bone-tendon graft was used; the tendon was split longitudinally to reconstruct both parts of the collateral ligament. This technique was modified by the author: a resorbable interference screw was used to fix a free tendon graft double in the metacarpal head, creating 2 identical bundles for reconstruction of both the proper and the accessory collateral ligament. The results of the first 10 patients with chronic ulnar instability in their otherwise intact thumb are reported. The mean follow-up was 15 months. Eight patients had excellent result and 2 patients had good result according to the Glickel grading system. The mean loss of motion in the metacarpophalengeal joint was 9% and the mean loss of pinch strength was 9% compared with the contralateral thumb. The technical details, pitfalls, complications, and rehabilitation are described in this paper.

Not all non-rheumatoid patients are satisfied with thumb metacarpophalangeal joint arthrodesis.

Arthrodesis of the thumb metacarpophalangeal (MP) joint exhibits good results in rheumatoid patients but is controversial in post-traumatic conditions. This study evaluated the subjective outcome after thumb MP joint arthrodesis in chronic injuries and non-rheumatoid degenerative disorders. Forty-six patients were evaluated retrospectively with a mean follow-up of 4.1 years (range 1.5-6.5). Both the Quick DASH score (mean 18.6; range 0-72.7) and Visual Analogue Scales (satisfaction, pain, stiffness, and impairment of ADL; mean 3.2, 3.0, 3.0, and 2.5; range 0-9.6, 0-9.1, 0-9.8, and 0-9.6, respectively) showed wide variations. Twelve patients regretted the operation and 37 experienced difficulties with one or more specific activities. Multiple regression analyses indicated that elderly patients with painless instability are the best candidates for thumb MP joint arthrodesis. In young patients with excessively painful thumb MP joints and involvement in Workers' Compensation Board claims, but without advanced degenerative changes, this study recommends avoiding arthrodesis and considering alternative treatment modalities. The importance of adequate preoperative information about the realistic expectations after arthrodesis of the thumb MP joint is emphasised.

Comparison of Transverse Intraosseous Loop Technique and Pull Out Suture for Reinsertion of the Flexor Digitorum Profundus tendon. A Retrospective Study.

We compared the results of two methods for reinsertion of flexor digitorum profundus tendons retrospectively. In 35 fingers of 29 patients pull-out suture and in 13 fingers of 11 patients transverse intraosseous loop technique was performed with a mean follow-up of 8 and 6 months, respectively. Eleven and nine fingers achieved "excellent" or "good" function according to Strickland and Glogovac at 8 weeks; 20 and ten at the last control in the pull-out and transverse intraosseous loop groups, respectively. The difference at 8 weeks was statistically significant in favour of the transverse intraosseous loop group. Ten patients underwent 12 complications in the pull-out group (four superficial infections; one rerupture, one PIP and one DIP joint contracture, one adhesion, two granulomas, one nail deformity and one carpal tunnel syndrome) and four of them were reoperated (one carpal tunnel release, one teno-arthrolysis and two resections of granuloma). There was no complication and no reoperation in the transverse intraosseous loop group, the difference being statistically significant for the former. In our study the transverse intraosseous loop technique seemed to be a safe alternative with possibly better functional results compared to the pull-out suture.

Comparison of modified Kessler and Yotsumoto-Dona suture: a biomechanical study on porcine tendons.

There is a need for a strong suture technique that allows early active mobilisation after repair of flexor tendons, but the best method has not yet been found. The aim of this study was to compare the modified Kessler suture biomechanically with a newer, two-strand suture. Eighteen porcine tendons were cut and repaired according to either the grasping modified Kessler suture or the combined side-locking loop technique (Yotsumoto) and interlocking horizontal mattress suture (Dona). The specimens were tested linearly to failure. The 2 mm gap force, yield force, ultimate force, stiffness, energy to yield, and energy to failure were all significantly higher (p value = 0.005, 0.003, <0.001, 0.001, 0.004, and 0.001, respectively) in the Yotsumoto-Dona group (median values (IQR): 30.9 (28.1-39.5) N, 82.7 (64.9-114.1) N, 82.7 (76.6-114.1) N, 12.5 (10-14.5) N/mm, 0.45 (0.2-0.5) J, and 0.45 (0.35-0.5) J) than in the modified Kessler group (25.8 (12.2-28.1) N, 35 (24.6-54.4) N, 50.9 (34.4-55.1) N, 7 (5.8-91) N/mm, 0.09 (0.06-0.18) J, and 0.21 (0.18-0.28) J). All Yotsumoto-Dona specimens had a yield force exceeding 35 N, while in the Kessler group only four did. The early yielding rate was 6/9 and 2/9 in the modified Kessler and the Yotsumoto-Dona groups, respectively (p = 0.15). Most of the core sutures failed by breakage, but three Yotsumoto knots loosened. All the simple running and six of the Dona epitendinous sutures failed predominantly by pulling-out, and by breakage at the intersections in three of the latter. The relatively easy two-strand Yotsumoto-Dona suture is likely to withstand the loads of active finger flexion, whereas the modified Kessler suture is probably not.