Airborne virus shedding of the alpha, delta, omicron SARS-CoV-2 variants and influenza virus in hospitalized patients.

Airborne transmission is an important transmission route for the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemiological data indicate that certain SARS-CoV-2 variants, like the omicron variant, are associated with higher transmissibility. We compared virus detection in air samples between hospitalized patients infected with different SARS-CoV-2 variants or influenza virus. The study was performed during three separate time periods in which subsequently the alpha, delta, and omicron SARS-CoV-2 variants were predominant. In total, 79 patients with coronavirus disease 2019 (COVID-19) and 22 patients with influenza A virus infection were included. Collected air samples were positive in 55% of patients infected with the omicron variant in comparison to 15% of those infected with the delta variant (p < 0.01). In multivariable analysis, the SARS-CoV-2 omicron BA.1/BA.2 variant (as compared to the delta variant) and the viral load in nasopharynx were both independently associated with air sample positivity, but the alpha variant and COVID-19 vaccination were not. The proportion of positive air samples patients infected with the influenza A virus was 18%. In conclusion, the higher air sample positivity rate of the omicron variant compared to previous SARS-CoV-2 variants may partially explain the higher transmission rates seen in epidemiological trends.

[Pneumomediastinum after minor wound to the neck]. / Pijnlijke gevolgen van een wond aan de hals.

A 47-year old male presented to the emergency department with a pneumomediastinum following a small penetrating wound to the neck.

Yield of Screening for COVID-19 in Asymptomatic Patients Before Elective or Emergency Surgery Using Chest CT and RT-PCR (SCOUT): Multicenter Study.

OBJECTIVE: To determine the yield of preoperative screening for COVID-19 with chest CT and RT-PCR in patients without COVID-19 symptoms. SUMMARY OF BACKGROUND DATA: Many centers are currently screening surgical patients for COVID-19 using either chest CT, RT-PCR or both, due to the risk for worsened surgical outcomes and nosocomial spread. The optimal design and yield of such a strategy are currently unknown. METHODS: This multicenter study included consecutive adult patients without COVID-19 symptoms who underwent preoperative screening using chest CT and RT-PCR before elective or emergency surgery under general anesthesia. RESULTS: A total of 2093 patients without COVID-19 symptoms were included in 14 participating centers; 1224 were screened by CT and RT-PCR and 869 by chest CT only. The positive yield of screening using a combination of chest CT and RT-PCR was 1.5% [95% confidence interval (CI): 0.8-2.1]. Individual yields were 0.7% (95% CI: 0.2-1.1) for chest CT and 1.1% (95% CI: 0.6-1.7) for RT-PCR; the incremental yield of chest CT was 0.4%. In relation to COVID-19 community prevalence, up to ∼6% positive RT-PCR was found for a daily hospital admission rate >1.5 per 100,000 inhabitants, and around 1.0% for lower prevalence. CONCLUSIONS: One in every 100 patients without COVID-19 symptoms tested positive for SARS-CoV-2 with RT-PCR; this yield increased in conjunction with community prevalence. The added value of chest CT was limited. Preoperative screening allowed us to take adequate precautions for SARS-CoV-2 positive patients in a surgical population, whereas negative patients needed only routine procedures.

Anomalous Freezing of Low-Dimensional Water Confined in Graphene Nanowrinkles.

Various properties of water are affected by confinement as the space-filling of the water molecules is very different from bulk water. In our study, we challenged the creation of a stable system in which water molecules are permanently locked in nanodimensional graphene traps. For that purpose, we developed a technique, nitrocellulose-assisted transfer of graphene grown by chemical vapor deposition, which enables capturing of the water molecules below an atomically thin graphene membrane structured into a net of regular wrinkles with a lateral dimension of about 4 nm. After successfully confining water molecules below a graphene monolayer, we employed cryogenic Raman spectroscopy to monitor the phase changes of the confined water as a function of the temperature. In our experiment system, the graphene monolayer structured into a net of fine wrinkles plays a dual role: (i) it enables water confinement and (ii) serves as an extremely sensitive probe for phase transitions involving water via graphene-based spectroscopic monitoring of the underlying water structure. Experimental findings were supported with classical and path integral molecular dynamics simulations carried out on our experimental system. Results of simulations show that surface premelting of the ice confined within the wrinkles starts at ∼200 K and the melting process is complete at ∼240 K, which is far below the melting temperature of bulk water ice. The processes correspond to changes in the doping and strain in the graphene tracked by Raman spectroscopy. We conclude that water can be confined between graphene structured into nanowrinkles and silica substrate and its phase transitions can be tracked via Raman spectral feature of the encapsulating graphene. Our study also demonstrated that peculiar behavior of liquids under spatial confinement can be inspected via the optical response of atomically thin graphene sensors.

Towards the evaluation of defects in MoS2 using cryogenic photoluminescence spectroscopy.

Characterization of the type and density of defects in two-dimensional (2D) transition metal dichalcogenides (TMDs) is important as the nature of these defects strongly influences the electronic and optical properties of the material, especially its photoluminescence (PL). Defect characterization is not as straightforward as it is for graphene films, where the D and D' Raman scattering modes easily indicate the density and type of defects in the graphene layer. Thus, in addition to the Raman scattering analysis, other spectroscopic techniques are necessary to perform detailed characterization of atomically thin TMD layers. We demonstrate that PL spectroscopy performed at liquid helium temperatures reveals the key fingerprints of defects in TMDs and hence provides valuable information about their origin and concentration. In our study, we address defects in chemical vapor deposition (CVD)-grown MoS2 monolayers. A significant difference is observed between the as-grown monolayers compared with the CVD-grown monolayers transferred onto a Si/SiO2 substrate, which contain extra defects due to the transfer process. We demonstrate that the temperature-dependent Raman and PL micro-spectroscopy techniques enable disentangling the contributions and locations of various defect types in TMD systems.

Superlattice in collapsed graphene wrinkles.

Topographic corrugations, such as wrinkles, are known to introduce diverse physical phenomena that can significantly modify the electrical, optical and chemical properties of two-dimensional materials. This range of assets can be expanded even further when the crystal lattices of the walls of the wrinkle are aligned and form a superlattice, thereby creating a high aspect ratio analogue of a twisted bilayer or multilayer - the so-called twisted wrinkle. Here we present an experimental proof that such twisted wrinkles exist in graphene monolayers on the scale of several micrometres. Combining atomic force microscopy and Raman spectral mapping using a wide range of visible excitation energies, we show that the wrinkles are extremely narrow and their Raman spectra exhibit all the characteristic features of twisted bilayer or multilayer graphene. In light of a recent breakthrough - the superconductivity of a magic-angle graphene bilayer, the collapsed wrinkles represent naturally occurring systems with tuneable collective regimes.

Introducing Well-Defined Nanowrinkles in CVD Grown Graphene.

The control of graphene's topography at the nanoscale level opens up the possibility to greatly improve the surface functionalization, change the doping level or create nanoscale reservoirs. However, the ability to control the modification of the topography of graphene on a wafer scale is still rather challenging. Here we present an approach to create well-defined nanowrinkles on a wafer scale using nitrocellulose as the polymer to transfer chemical vapor deposition grown graphene from the copper foil to a substrate. During the transfer process, the complex tertiary nitrocellulose structure is imprinted into the graphene area layer. When the graphene layer is put onto a substrate this will result in a well-defined nanowrinkle pattern, which can be subsequently further processed. Using atomic force and Raman microscopy, we characterized the generated nanowrinkles in graphene.

A step up therapeutic regimen for chronic post-Pfannenstiel pain syndrome.

OBJECTIVE: Up to 8% of patients undergoing surgery via a Pfannenstiel incision may develop chronic inguinal pain. This type of pain is frequently caused by inguinal nerve entrapment and may strongly interfere with daily functioning. We report our long term experience of a step up approach using tender point infiltration and surgical neurectomy for intractable neuropathic post-Pfannenstiel groin pain. STUDY DESIGN: A retrospective database analysis identified patients with neuropathic groin pain due to iliohypogastric and/or ilioinguinal nerve entrapment following a Pfannenstiel incision in a single center between 2000 and 2015. Patients who underwent a neurectomy completed a previously published questionnaire including preoperative pain characteristics, pain reduction (5-point Verbal Rating Scale (VRS) and percentages), functional impairment, complications, recurrence of pain and current need for pain medication. RESULTS: Data of 186 women treated for chronic post-Pfannenstiel neuralgia during this 15 year time period were available. Pain reduction following tender point infiltration was successful in 24 patients (13%). In total, 134 of 144 women who underwent a neurectomy were available for follow up via the questionnaire, and 101 responded (response rate 75%). Median age was 52 years (49-54). Before operation, 87% (n = 88) suffered from (very) severe pain (median VRS of 4, range 3-5). Almost 5 years after the operation (median 57 months, range 8-189), 54% (n = 55) had no or only mild pain (p < 0.001). Two of three women reported at least >50% pain reduction and improvement of daily functioning. Eight patients (8%) experienced recurrence of pain after an initial substantial pain reduction. CONCLUSIONS: A step-up approach of tender point infiltration and surgical neurectomy is an effective treatment option in the majority of women with chronic post-Pfannenstiel pain syndrome. Surgeons, gynecologists and pain specialists should consider adopting this treatment regimen for chronic post-Pfannenstiel pain due to nerve entrapment.

Selective self-assembly and light emission tuning of layered hybrid perovskites on patterned graphene.

The emission of light in two-dimensional (2-D) layered hybrid organic lead halide perovskites, namely (R-NH3)2PbX4, can be effectively tuned using specific building blocks for the perovskite formation. Herein this behaviour is combined with a non-covalent graphene functionalization allowing excellent selectivity and spatial resolution of the perovskite film growth, promoting the formation of hybrid 2-D perovskite : graphene heterostructures with uniform coverage of up to centimeter scale graphene sheets and arbitrary shapes down to 5 µm. Using cryo-Raman microspectroscopy, highly resolved spectra of the perovskite phases were obtained and the Raman mapping served as a convenient spatially resolved technique for monitoring the distribution of the perovskite and graphene constituents on the substrate. In addition, the stability of the perovskite phase with respect to the thermal variation was inspected in situ by X-ray diffraction. Finally, time-resolved photoluminescence characterization demonstrated that the optical properties of the perovskite films grown on graphene are not hampered. Our study thus opens the door to smart fabrication routes for (opto)-electronic devices based on 2-D perovskites in contact with graphene with complex architectures.

Electronic and mechanical response of graphene on BaTiO3 at martensitic phase transitions.

Graphene is extremely sensitive to optical, electrical and mechanical stimuli, which cause a significant variation of the band structure, thus the physiochemical properties. In our work, we report on changes of strain and doping in graphene grown by chemical vapor deposition on copper and transferred onto a BaTiO3(1 0 0) (BTO) single-crystal. The BTO is known as a ferroelectric material, which undergoes several thermoelastic martensitic phase transitions when it is cooled from 300 K to 10 K. In order to enhance the very weak Raman signal of the graphene monolayer (ML) on the BTO, a 15 nm thin gold layer was deposited on top of the graphene ML to benefit from the surface enhanced Raman scattering. Using temperature dependent Raman spectral mapping, the principal Raman modes (D, G and 2D) of the graphene ML were followed in situ. From a careful analysis of these Raman modes, we conclude that the induced strain and doping of the graphene ML follows the martensitic phase transitions of the BTO crystal. Our study suggests potential exploitation of the graphene as a highly sensitive opto-mechanical sensor or transducer.

The GroinPain Trial: A Randomized Controlled Trial of Injection Therapy Versus Neurectomy for Postherniorraphy Inguinal Neuralgia.

OBJECTIVE: This study compares tender point infiltration (TPI) and a tailored neurectomy as the preferred treatment for chronic inguinodynia after inguinal herniorraphy. BACKGROUND: Some 11% of patients develop chronic discomfort after open inguinal herniorraphy. Both TPI and neurectomy have been suggested as treatment options, but evidence is conflicting. METHODS: Patients with chronic neuropathic pain after primary Lichtenstein repair and >50% pain reduction after a diagnostic TPI were randomized for repeated TPI (combined Lidocaine/corticosteroids /hyaluronic acid injection) or for a neurectomy. Primary outcome was success (>50% pain reduction using Visual Analog Scale, VAS) after 6 months. Cross-over to neurectomy was offered if TPI was unsuccessful. RESULTS: A total of 54 patients were randomized in a single center between January 2006 and October 2013. Baseline VAS was similar (TPI: 55, range 10-98 vs neurectomy: 53, range 18-82, P = 0.86). TPI was successful in 22% (n = 6), but a neurectomy was successful in 71% (n = 17, P = 0.001). After unsuccessful TPI, 19 patients crossed over to neurectomy and their median VAS score dropped from 60 to 14 (P = 0.001). No major complications after surgery were reported. Two-thirds of patients on worker's compensation returned to work. CONCLUSION: A tailored neurectomy is 3 times more effective than tender point infiltration in chronic inguinodynia after anterior inguinal hernia mesh repair. A step up treatment stratagem starting with tender point infiltration followed by a tailored neurectomy is advised.

Groin Pain Characteristics and Recurrence Rates: Three-year Results of a Randomized Controlled Trial Comparing Self-gripping Progrip Mesh and Sutured Polypropylene Mesh for Open Inguinal Hernia Repair.

OBJECTIVE: The aim of this study was to investigate long-term groin pain and inguinal hernia recurrence rates of 2 types of mesh and to describe the evolution of postoperative groin sensory disturbances. SUMMARY OF BACKGROUND DATA: Some patients with an inguinal hernia develop chronic pain following open mesh insertion. Previous trials comparing a semi-resorbable, self-gripping Progrip mesh with a standard sutured polypropylene mesh found conflicting results regarding recurrence rates and residual groin pain. METHODS: Patients aged >18 years scheduled for open primary hernia repair were randomized to a self-gripping mesh (Progrip) or a polypropylene mesh (standard). Removal of the inguinal nerves was left to the discretion of the surgeon. Pain was measured using Visual Analogue Scale (VAS) over a 3-year period. Pain characteristics and hernia recurrences were determined using physical examination. RESULTS: Data of 274 patients were complete (75% three-year follow-up rate). Pain steadily decreased over time in both groups in a similar fashion (moderate pain 3.7% in each group). Hyperesthesia was experienced by 2.2% and 3.7% and hypoesthesia in 12% and 19% in Progrip and standard group, respectively. One of seven Progrip patients reported a foreign body feeling versus 1 of 5 standard patients (P = 0.06). Altered skin sensations were not related to a neurectomy. Hernia recurrence rate was 11.5% in the Progrip and 5% in the standard group (P = 0.05). CONCLUSIONS: Three years after insertion of a self-gripping Progrip mesh or a sutured polypropylene mesh for an open primary inguinal hernia repair, groin pain is minimal, although altered groin skin sensations and foreign body feeling are quite common. A Progrip hernia repair is associated with a high recurrence rate.

Mastering the Wrinkling of Self-supported Graphene.

We present an approach that allows for the preparation of well-defined large arrays of graphene wrinkles with predictable geometry. Chemical vapor deposition grown graphene transferred onto hexagonal pillar arrays of SiO2 with sufficiently small interpillar distance forms a complex network of two main types of wrinkle arrangements. The first type is composed of arrays of aligned equidistantly separated parallel wrinkles propagating over large distances, and originates from line interfaces in the graphene, such as thin, long wrinkles and graphene grain boundaries. The second type of wrinkle arrangement is composed of non-aligned short wrinkles, formed in areas without line interfaces. Besides the presented hybrid graphene topography with distinct wrinkle geometries induced by the pre-patterned substrate, the graphene layers are suspended and self-supporting, exhibiting large surface area and negligible doping effects from the substrate. All these properties make this wrinkled graphene a promising candidate for a material with enhanced chemical reactivity useful in nanoelectronic applications.

Graphene wrinkling induced by monodisperse nanoparticles: facile control and quantification.

Controlled wrinkling of single-layer graphene (1-LG) at nanometer scale was achieved by introducing monodisperse nanoparticles (NPs), with size comparable to the strain coherence length, underneath the 1-LG. Typical fingerprint of the delaminated fraction is identified as substantial contribution to the principal Raman modes of the 1-LG (G and G'). Correlation analysis of the Raman shift of the G and G' modes clearly resolved the 1-LG in contact and delaminated from the substrate, respectively. Intensity of Raman features of the delaminated 1-LG increases linearly with the amount of the wrinkles, as determined by advanced processing of atomic force microscopy data. Our study thus offers universal approach for both fine tuning and facile quantification of the graphene topography up to ~60% of wrinkling.

Factors Determining Outcome After Surgery for Chronic Groin Pain Following a Lichtenstein Hernia Repair.

BACKGROUND: Some patients develop chronic groin pain after a Lichtenstein hernia repair. Previous studies have demonstrated beneficial effects of removal of entrapped inguinal nerves or a meshectomy in patients with chronic pain after open inguinal hernia mesh repair. Factors determining success following this remedial surgery are unknown. The aim of the study was to identify potential patient- or surgery-related factors predicting the surgical efficacy for inguinodynia following Lichtenstein repair. METHODS: Consecutive adult patients with a history of persistent pain following Lichtenstein repair who underwent remedial surgery were analysed using univariate analysis. Significant confounders (p < 0.05) were combined in a multivariate logistic regression model using a backward stepwise regression method. RESULTS: A total of 136 groin pain operations were available for analysis. Factors contributing to success were removal of a meshoma (OR 4.66) or a neuroma (OR 5.60) and the use of spinal anaesthesia (OR 4.38). In contrast, female gender (OR 0.30) and preoperative opioid use (OR 0.38) were significantly associated with a less favourable outcome. Using a multivariate analysis model, surgery under spinal anaesthesia (OR 4.04), preoperative use of opioids (OR 0.37), and meshoma removal (OR 5.31) greatly determined surgical outcome. CONCLUSIONS: Pain reduction after remedial surgery for chronic groin pain after Lichtenstein repair is more successful if surgery is performed under spinal anaesthesia compared to general anaesthesia. Removal of a meshoma must be considered as success rates are optimized following these measures. Patients using opioids preoperatively have less favourable outcomes.