Pre-lens tear film evaluation scale: a tool for analyzing the tear film-lens interaction with respect to the material used

In clinical practice, to avoid or reduce the failure rate among users of contact lenses, it is necessary to obtain a detailed patient case history, information concerning symptoms, and a complete eye examination. In addition, application of an auxiliary photographic reference scale might increase the chances of improving initial success or, for existing contact lens wearers, provide insight into the extent or severity of symptoms. Patient symptoms are often directly related to contact lens failure, which in turn is related to the quality of the pre-corneal tear film as well as the wettability of the contact lens surface. We describe the relationship between the quality of the tear film, with particular attention to pre-contact lens tear film, variability in contact tolerance, and the material of which the contact lens is made

Amplified spontaneous emission in quaterthiophene single crystals

The authors demonstrate amplified spontaneous emission (ASE) from quaterthiophene single crystals and study its behavior at low temperature. The room temperature photoluminescence exhibits line narrowing (spectral width down to 10nm) at 553nm for excitation fluence larger than 1mJcm−2. At low temperature (10K), ASE is observed from two vibronic transitions at 510nm (0-1) and 553nm (0–2), with line narrowing down to 5A, for fluences larger than 100μJcm−2. The stimulated emission cross section is of the order of 10−15cm2, and the ASE is found to be strongly affected by thermally induced dynamic disorder. The emission stability under photopumping is also studied and discussed

Surface perfluoroalkyl chains segregation : a tool for reducing calcium deposits in medical grade poly(methyl methacrylate)

Intraocular lenses can be manufactured from a wide variety of polymers, but due to the lost cost associated with the use of Poly(methyl methacrylate) (PMMA), it is still the preferred material used in the developing countries. However, a major drawback to its use is the build-up of calcium containing deposits that are formed on the intraocular lens over a period of time. In an attempt to hinder this deposition, surface modification of medical grade PMMA has been carried out using perfluoroalkyl chain (1,2,4-trifluoro-3- (C10F21CH2O)-7-(N,N)-dimethylaminoacridine) segregation. The segregation was explored using a 1% 1,2,4-trifluoro-3-(C10F21CH2O)-7-(N,N)-dimethyla- minoacridine in two methods: film casting and spin-coating, a thin film onto preformed PMMA discs. Both methods were compared against control PMMA to determine which method provided the best hindrance against calcium containing deposits when immersed in a simulated aqueous humour solution. Characterisation of the surface using scanning electron microscopy coupled with energy; dispersive x-ray analysis indicated that the surface segregation of perfluoroalkyl chains had hindered calcification in both methods. This pleminary research shows promising results of employing perfluoroalkyl chains in the surface segregation of biomaterials that can be employed in intraocular lenses

Sulfur hexafluoride (SF₆) plasma treatment of medical grade poly(methyl methacrylate)

Medical-grade poly(methyl methacrylate) (PMMA) is widely employed in the fabrication of intraocular lenses (IOLs), but suffers from opacification, a postoperative complication that leads to the failure of the implanted intraocular lenses. The opacification occurs when inorganic-based deposits accumulate on the surface of the IOL and are prevalent in hydrophilic materials. Here, the surface of medical-grade PMMA has been fluorinated by sulphur hexafluoride (SF₆) plasma treatment to increase surface hydrophobicity thus improving the material lifetime in optical applications. Hydrophobic properties of the treated PMMA were investigated by means of contact angle measurements, while chemical modification was assessed by X-ray Photoelectron Spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transform Infrared (ATR/FTIR) spectroscopy. Surface morphological changes due to possible etching effects were investigated by Atomic Force Microscopy (AFM). The transparency of the treated PMMA was assessed by UV/VIS spectroscopy. Finally, the influence of the plasma treatment on the inorganic salts deposition was investigated by immersion in Simulated Aqueous Humour (SAH), followed by XPS analysis. The modified samples showed less deposition on the surface than the unmodified sample, moreover, a decrease of the transmittance in the UV-violet range (300–430 nm) was detected, open the possibility of interesting applications of this treatment for the creation of a UV filter in ophthalmic optical devices

Bypassing the statistical limit of singlet generation in sensitized upconversion using fluorinated conjugated systems

The photon upconversion based on triplet–triplet annihilation (TTA) is a mechanism that converts the absorbed low-energy electromagnetic radiation into higher energy photons also at extremely low excitation intensities, but its use in actual technologies is still hindered by the limited availability of efficient annihilator moieties. We present here the results obtained by the synthesis and application of two new fluorinated chromophores based on phenazine and acridine structures, respectively. Both compounds show upconverted emission demonstrating their ability as TTA annihilator. More interesting, the acridine-based chromophore shows an excellent TTA yield that overcomes the one of some of best model systems. By correlating the experimental data and the quantum mechanical modeling of the investigated compound, we propose an alternative efficient pathway for the generation of the upconverted emissive states involving the peculiar high-energy triplet levels of the dye, thus suggesting a new development strategy for TTA annihilators based on the fine tuning of their high-energy excited states properties

Monolithic vertical microcavities based on tetracene single crystals

The authors report on monolithic, light-emitting vertical microcavities based on an organic semiconductor single crystal. The devices are realized by reactive electron-beam deposition of dielectric mirrors and growth of tetracene crystals by physical vapor transport. The microcavities exhibit optical cavity modes in the visible range (550–580nm) with full width at half maximum down to 2–3nm, corresponding to a Q factor of about 200, and polarization-induced modal splitting up to 20meV. These results open perspectives for the realization of polarized-emitting optoelectronic devices based on organic crystals

Functional Π-conjugated polymers based on maleimide for photovoltaic applications

A series of new bis-(2-thienyl) maleimide monomers have been synthesized and characterized. The bis-(2thienyl)maleimide unit has been copolymerized with dierent aromatic comonomers. Stille coupling polymerizations under various conditions have been utilized. The copolymers were then characterized by size-exclusion chromatography and their optical and electronic properties were investigated by UV-Vis absorption spectroscopy and cyclic voltammetry. All maleimide based copolymers shared similar LUMO energy levels, which are largely determined by the acceptor moiety, and are close to that of PC61BM to be eective for charge dissociation. These low band gap polymers have been tested for photovoltaic applications and have shown moderate photovoltaic performance. Interesting results were obtained by adding the polymer to the P3HT:PC61BM mixture, as a third component. The ternary blend BHJ solar cells showed power conversion eciencies of 35% exceeding those of the corresponding binary blends

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study

Background: In 2020, ACIE Appy study showed that COVID-19 pandemic heavily affected the management of patients with acute appendicitis (AA) worldwide, with an increased rate of non-operative management (NOM) strategies and a trend toward open surgery due to concern of virus transmission by laparoscopy and controversial recommendations on this issue. The aim of this study was to survey again the same group of surgeons to assess if any difference in management attitudes of AA had occurred in the later stages of the outbreak. Methods: From August 15 to September 30, 2021, an online questionnaire was sent to all 709 participants of the ACIE Appy study. The questionnaire included questions on personal protective equipment (PPE), local policies and screening for SARS-CoV-2 infection, NOM, surgical approach and disease presentations in 2021. The results were compared with the results from the previous study. Results: A total of 476 answers were collected (response rate 67.1%). Screening policies were significatively improved with most patients screened regardless of symptoms (89.5% vs. 37.4%) with PCR and antigenic test as the preferred test (74.1% vs. 26.3%). More patients tested positive before surgery and commercial systems were the preferred ones to filter smoke plumes during laparoscopy. Laparoscopic appendicectomy was the first option in the treatment of AA, with a declined use of NOM. Conclusion: Management of AA has improved in the last waves of pandemic. Increased evidence regarding SARS-COV-2 infection along with a timely healthcare systems response has been translated into tailored attitudes and a better care for patients with AA worldwide

Acute diverticulitis management: evolving trends among Italian surgeons. A survey of the Italian Society of Colorectal Surgery (SICCR)

Acute diverticulitis (AD) is associated with relevant morbidity/mortality and is increasing worldwide, thus becoming a major issue for national health systems. AD may be challenging, as clinical relevance varies widely, ranging from asymptomatic picture to life-threatening conditions, with continuously evolving diagnostic tools, classifications, and management. A 33-item-questionnaire was administered to residents and surgeons to analyze the actual clinical practice and to verify the real spread of recent recommendations, also by stratifying surgeons by experience. CT-scan remains the mainstay of AD assessment, including cases presenting with recurrent mild episodes or women of child-bearing age. Outpatient management of mild AD is slowly gaining acceptance. A conservative management is preferred in non-severe cases with extradigestive air or small/non-radiologically drainable abscesses. In severe cases, a laparoscopic approach is preferred, with a non-negligible number of surgeons confident in performing emergency complex procedures. Surgeons are seemingly aware of several options during emergency surgery for AD, since the rate of Hartmann procedures does not exceed 50% in most environments and damage control surgery is spreading in life-threatening cases. Quality of life and history of complicated AD are the main indications for delayed colectomy, which is mostly performed avoiding the proximal vessel ligation, mobilizing the splenic flexure and performing a colorectal anastomosis. ICG is spreading to check anastomotic stumps' vascularization. Differences between the two experience groups were found about the type of investigation to exclude colon cancer (considering the experience only in terms of number of colectomies performed), the size of the peritoneal abscess to be drained, practice of damage control surgery and the attitude towards colovesical fistula

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6 years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P < 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100 years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception