Closed-Loop Recycling of Vinylogous Urethane Vitrimers.

Devising energy-efficient strategies for the depolymerization of plastics and the recovery of their structural components in high yield and purity is key to a circular plastics economy. Here, we report a case study in which we demonstrate that vinylogous urethane (VU) vitrimers synthesized from bis-polyethylene glycol acetoacetates (aPEG) and tris(2-aminoethyl)amine can be degraded by water at moderate temperature with almost quantitative recovery (≈98 %) of aPEG. The rate of depolymerization can be controlled by the temperature, amount of water, molecular weight of aPEG, and composition of the starting material. These last two parameters also allow one to tailor the mechanical properties of the final materials, and this was used to access soft, tough, and brittle vitrimers, respectively. The straightforward preparation and depolymerization of the aPEG-based VU vitrimers are interesting elements for the design of polymer materials with enhanced closed-loop recycling characteristics.

An electrolyte additive for the improved high voltage performance of LiNi0.5Mn1.5O4 (LNMO) cathodes in Li-ion batteries.

High-voltage cathode materials are important for the implementation of high-energy-density Li-ion batteries. However, with increasing cut-off voltages, interfacial instabilities between electrodes and the electrolyte limit their commercial development. This study addresses this issue by proposing a new electrolyte additive, (3-aminopropyl)triethoxysilane (APTS). APTS stabilises the interface between the LiNi0.5Mn1.5O4 (LNMO) cathode and the electrolyte in LNMO‖Li half-cells due to its multifunctional character. The amino groups in APTS facilitate the formation of a robust protective cathode layer. Its silane groups improve layer stability by neutralising the electrolyte's detrimental hydrogen fluoride and water. Electrochemical measurements reveal that the addition of 0.5 wt% APTS significantly improves the long-term cycling stability of LNMO‖Li half-cells at room temperature and 55 °C. APTS-addition to the electrolyte delivers excellent capacity retention of 92% after 350 cycles at room temperature and 71% after 300 cycles at 55 °C (1C) contrasting with the much lower performances of the additive-free electrolyte. The addition of a 0.5 wt% (3-glycidyloxypropyl)trimethoxysilane (GLYMO) additive, which contains only the siloxane group, but lacks the amine group, displayed a capacity retention of 73% after 350 cycles at room temperature but degraded significantly upon cycling at 55 °C.

Chronic cough in post-COVID syndrome: Laryngeal electromyography findings in vagus nerve neuropathy.

BACKGROUND: Despite being a new entity, there is a large amount of information on the characteristics of SARS-CoV-2 infection and the symptoms of the acute phase; however, there are still many unknowns about the clinical features and pathophysiology of post-COVID syndrome. Refractory chronic cough is one of the most prevalent symptoms and carries both a medical problem and a social stigma. Many recent studies have highlighted the role of SARS-CoV-2 neurotropism, but no studies have demonstrated vagus nerve neuropathy as a cause of persistent chronic cough or other COVID-19 long-term effects. OBJECTIVE: The main objective was to assess the involvement of the vagus nerve neuropathy as a cause of chronic cough and other post-COVID syndrome symptoms. MATERIAL AND METHODS: This was a single-center observational study with prospective clinical data collected from 38 patients with chronic cough and post-COVID-19 syndrome. Clinical characteristics and laryngeal electromyographic findings were analyzed. RESULTS: Clinical data from 38 patients with chronic cough after 12 weeks of the acute phase of COVID-19 infection were analyzed. Of these patients, 81.6% suffered from other post-COVID conditions and, 73.6% reported fluctuating evolution of symptoms. Laryngeal electromyography (LEMG) of the thyroarytenoid (TA) muscles and cricothyroid (CT) muscles was pathological in 76.3% of the patients. Of the patients with abnormal LEMG, chronic denervation was the most frequent finding (82.8%), 10.3% presented acute denervation signs, and 6.9% presented myopathic pattern in LEMG. CONCLUSIONS: LEMG studies suggest the existence of postviral vagus nerve neuropathy after SARS-CoV-2 infection that could explain chronic cough in post-COVID syndrome.

Computational design of anisotropic nanocomposite actuators.

This paper presents a theoretical investigation of the design of a new actuator type made of anisotropic colloidal particles grafted with stimuli-responsive polymer chains. These artificial muscles combine the osmotic actuation principle of stimuli-responsive hydrogels with the structural alignment of colloidal liquid crystals to achieve directional motion. The solubility of the stimuli-responsive polymer in the neutral state, its degree of polymerization, the salt concentration, and the grafting density of the polymer chains on the surface of the colloidal particles are investigated and identified as important for actuator performance and tunability. The computational results suggest that the proposed mechanically active material matches or exceeds the performances of natural muscles and provide the guidelines for the realization of artificial muscles with predetermined actuation properties.

Audiological evaluation (128-20,000Hz) in women with autoimmune thyroiditis: The role of antibodies vs. l-thyroxine deficiency.

BACKGROUND AND AIM: Although sensorineural hearing loss may have different aetiologies, we focused on autoimmune hearing loss since it may be reversible with corticosteroid therapy; this entity is sometimes associated with systemic autoimmune diseases. Hashimoto's thyroiditis or chronic autoimmune thyroiditis shows antibodies and may be harmful to hearing thresholds regardless of hypothyroidism effect. To date this effect has not been sufficiently studied and never with extended high frequencies. The aim of this work is to study by age groups whether hearing thresholds in the human auditory range (128-20,000Hz) are affected in Hashimoto's disease. MATERIALS AND METHODS: Two groups of 128 patients affected by Hashimoto's thyroiditis were included. First group: patients with pathological antithyroid antibodies who do not need L-thyroxine treatment. Second group: patients controlled with L-thyroxine substitutive treatment. Audiometric threshold study comparing between the groups of patients and a group of 209 controls was performed. All patients underwent complete otorhinolaryngological examination, antithyroid antibodies, TSH, T3 and T4 blood levels, tympanometry, conventional pure-tone audiometry, and extended-high-frequency audiometry. RESULTS: All patients were women. Both groups showed worst audiometric thresholds than the control group; both study groups showed worse hearing than controls, this difference was statistically significant in all frequencies. In the 8-20kHz frequency range, this difference was more than 10dB, and in the 9-16kHz and 20kHz range this difference was more than 20dB. When separated by age groups, in younger subjects (20-29 years) these differences were found in all frequencies, except for conversational frequencies (500-4,000Hz); between 30 and 49 years the difference is statistically significant in all frequencies; and from 50 to 69 years differences are found, especially in the conversational frequencies. CONCLUSIONS: This first work studying the human auditory range in the chronic autoimmune thyroiditis or Hashimoto's thyroiditis confirms that hearing loss related to the autoimmune disorder predominates at extended-high-frequencies initially. But ends up involving all frequencies in pure-tone conventional audiometry, then it may be detected in routine clinical tests. These results support the role of extended-high-frequencies audiometry to diagnose subclinical hearing loss in patients affected by Hashimoto's thyroiditis.

Estudio de la audición (128-20.000 Hz) en mujeres con tiroiditis autoinmune: papel de los anticuerpos frente al déficit de hormona tiroidea / Audiological evaluation (128-20.000 Hz) in women with autoinmune thyroiditis: The role of antibodies vs. l-thyroxine deficiency

Antecedentes y objetivo: Hay muchas causas de hipoacusia neurosensorial, entre las que tiene especial interés la patología autoinmune del oído interno por su posible reversibilidad con tratamiento esteroideo, a veces asociada a enfermedades sistémicas autoinmunes. La tiroiditis crónica autoinmune o de Hashimoto (TA) presenta anticuerpos que podrían afectar al oído interno independientemente del hipotiroidismo, efecto que no ha sido suficientemente estudiado y nunca mediante audiometría con extensión en altas frecuencias.El objetivo de este trabajo es estudiar si existe afectación de los umbrales auditivos en pacientes de TA, sin hipotiroidismo, en la totalidad del espectro auditivo humano (128 Hz – 20 kHz) distribuido por grupos de edad.Materiales y métodosSe han seleccionado 128 pacientes divididos en dos grupos. El primer grupo de pacientes presenta anticuerpos antitiroideos elevados sin necesitar tratamiento sustitutivo con tiroxina. El segundo grupo con tratamiento sustitutivo con tiroxina, bien controlados. Se comparan con el grupo control (GC) de 209 pacientes. En todos se realizó historia clínica, exploración otológica, estudio de niveles de anticuerpos antitiroideos, TSH (thyroid-stimulating hormone), T3 y T4 libres, timpanograma, estudio audiométrico convencional y con extensión en altas frecuencias.ResultadosTodos los pacientes fueron mujeres. Ambos grupos mostraron peor audición que los controles, siendo la diferencia estadísticamente significativa en todas las frecuencias; en el rango de frecuencias de 8 – 20 kHz con una diferencia de más de 10 dB, y en los rangos de 9-16 kHz y de 20 kHz de más de 20 dB. (AU)

Background and aim: Although sensorineural hearing loss may have different aetiologies, we focused on autoimmune hearing loss since it may be reversible with corticosteroid therapy; this entity is sometimes associated with systemic autoimmune diseases. Hashimoto's thyroiditis or chronic autoimmune thyroiditis shows antibodies and may be harmful to hearing thresholds regardless of hypothyroidism effect. To date this effect has not been sufficiently studied and never with extended high frequencies. The aim of this work is to study by age groups whether hearing thresholds in the human auditory range (128 to 20.000 Hz) are affected in Hashimoto's disease.Materials and methodsTwo groups of 128 patients affected by Hashimoto's thyroiditis were included. First group: patients with pathological antithyroid antibodies who do not need L-thyroxine treatment. Second group: patients controlled with L-thyroxine substitutive treatment. Audiometric threshold study comparing between the groups of patients and a group of 209 controls was performed. All patients underwent complete otorhinolaryngological examination, antithyroid antibodies, TSH, T3 and T4 blood levels, tympanometry, conventional pure-tone audiometry, and extended-high-frequency audiometry.ResultsAll patients were women. Both groups showed worst audiometric thresholds than the control group; both study groups showed worse hearing than controls, this difference was statistically significant in all frequencies. In the 8-20 kHz frequency range this difference was more than 10 dB, and in the 9-16 kHz and 20 kHz range this difference was more than 20 dB. When separated by age groups, in younger subjects (20-29 years) these differences were found in all frequencies, except for conversational frequencies (500 - 4,000 Hz); between 30 and 49 years the difference is statistically significant in all frequencies; and from 50 to 69 years differences are found, especially in the conversational frequencies. (AU)

Chemical Upcycling of Conventional Polyureas into Dynamic Covalent Poly(aminoketoenamide)s.

The chemical upcycling of polymers is an emerging strategy to transform post-consumer waste into higher-value chemicals and materials. However, on account of the high stability of the chemical bonds that constitute their main chains, the chemical modification of many polymers proves to be difficult. Here, we report a versatile approach for the upcycling of linear and cross-linked polyureas, which are widely used because of their high chemical stability. The treatment of these polymers or their composites with acetylacetone affords di-vinylogous amide-terminated compounds in good yield. These products can be reacted with aromatic isocyanates, and the resulting aminoketoenamide bonds are highly dynamic at elevated temperatures. We show here that this conversion scheme can be exploited for the preparation of dynamic covalent poly(aminoketoenamide) networks, which are healable and reprocessable through thermal treatment without any catalyst.

Supramolecular Stability of Benzene-1,3,5-tricarboxamide Supramolecular Polymers in Biological Media: Beyond the Stability-Responsiveness Trade-off.

Supramolecular assemblies have been gaining attention in recent years in the field of drug delivery because of their unique formulation possibilities and adaptive behavior. Their non-covalent nature allows for their self-assembly formulation and responsiveness to stimuli, an appealing feature to trigger a therapeutic action with spatiotemporal control. However, facing in vivo conditions is very challenging for non-covalent structures. Dilution and proteins in blood can have a direct impact on self-assembly, destabilizing the supramolecules and leading to a premature and uncontrolled cargo release. To rationalize this behavior, we designed three monomers exhibiting distinct hydrophobic cores that self-assemble into photo-responsive fibers. We estimated their stability-responsiveness trade-off in vitro, finding two well-separated regimes. These are low-robustness regime, in which the system equilibrates quickly and responds readily to stimuli, and high-robustness regime, in which the system equilibrates slowly and is quite insensitive to stimuli. We probed the performance of both regimes in a complex environment using Förster resonance energy transfer (FRET). Interestingly, the stability-responsiveness trade-off defines perfectly the extent of disassembly caused by dilution but not the one caused by protein interaction. This identifies a disconnection between intrinsic supramolecular robustness and supramolecular stability in the biological environment, strongly influenced by the disassembly pathway upon protein interaction. These findings shed light on the key features to address for supramolecular stability in the biological environment.

Seroprevalence of antibodies against to SARS-CoV 2 in umbilical cord blood in two hospital centers in Córdoba and Sucre, Colombia.

INTRODUCTION: Pregnant women continue to be vulnerable to COVID-19, and their immunosuppressed state could put them at greater risk of developing more severe forms of the disease. In Colombia and Latin America, there are few studies on the immune response of the newborn against SARS-CoV-2. AIM: To determine the prevalence of SARS-CoV-2 infection in umbilical cord blood in two hospital centers in Córdoba and Sucre. METHODS: Between March and June 2021, a prospective descriptive cross-sectional study was carried out. Two hospitals from the departments of Córdoba and Sucre, located in the Northwest Caribbean area of Colombia, participated. Three hundred sixty umbilical cord blood samples were taken at the two hospitals. A commercial ELISA was performed to detect total IgG, IgM, and IgA antibodies against the N protein of SARS-CoV-2. The ethics committee approved the study of the participating institutions. RESULTS: Of 3.291 women who gave birth in the hospital centers included in the study, 360 (11%) participated. Complete clinical data were obtained for 223 women. The mean age of the women was 24 years (range, 15-42). 29.4% (106/360) of the umbilical cord samples had total antibodies against SARS-CoV-2. Pregnant women did not have blood samples taken. 58% of the women were asymptomatic. There was no association between umbilical cord samples, clinical, epidemiological characteristics, and serological response to antibodies to SARS-CoV-2 (p > 0.05). CONCLUSIONS: The prevalence of umbilical cord blood samples was 29.4% for total SARS-CoV-2 antibodies. The study provides essential aspects for the epidemiological approach to neonates infected with SARS-CoV-2.

Phenotypic Characterization of Laryngospasm: The Utility of Laryngeal Neurophysiological Studies.

OBJECTIVE: To determine the existence of laryngeal neuropathy and the influence of gastroesophageal reflux in patients with episodic laryngospasm. STUDY DESIGN: Single -center, observational study with prospective clinical collection. STUDY SETTING: Prospective analysis of 18 Spanish patients with episodic laryngospasm in a Spanish Public Center collected by otolaryngologist. The recruitment dates were from January 2019 to December 2019. METHODS: Data collection of 18 patients with episodic laryngospasm. Clinical characteristics, laryngeal neurophysiological studies and reflux esophageal testing were analyzed. RESULTS: All patients have a trigger for the laryngospasms, being the most prevalent adopting the supine position (27.7%). EMG and ENG were pathological in 83.3 and 63.6 % respectively. Chronic bilateral denervation (increased amplitude and duration of potentials) with signs of reinnervation in the non-active chronic phase (large polyphasia), was the most prevalent finding. Evidence of gastroesophageal reflux either by pH meter, Gastroscopy or both was found in 38.8 % of patients. CONCLUSIONS: Neurophysiological studies have confirmed the existence of laryngeal neuropathy in the majority of patients with laryngospasm. A substantial percentage of patients (38.8%) with laryngospasm had objective GERD and improved with PPIs. Laryngeal EMG and ENG can establish a more accurate diagnostic for episodic laryngospams and may supports treatment with neuromodulators.

Polyaromatic cores for the exfoliation of popular 2D materials.

Two-dimensional (2D) nanomaterials have attracted interest from the scientific community due to their unique properties. The production of these materials has been carried out by diverse methodologies, the liquid phase exfoliation being the most promising one due to its simplicity and potential scalability. The use of several stabilizers allows to obtain dispersions of these 2D nanomaterials in solvents with low boiling points. Herein we describe a general exfoliation method for different 2D materials employing a biphasic water/dichloromethane system and two different (poly)aromatic hydrocarbons (PAHs). This method allows us to obtain dispersions of the exfoliated 2D materials with high concentrations in the organic solvent. Due to the low boiling point of dichloromethane, and therefore its easy removal, the obtained dispersions can be employed as additives for different composites. We corroborate that the exfoliation efficiency is improved due to the π-π and van der Waals interactions between the PAHs and the layers of the 2D materials.

Utility and limitations of metabolic parameters in head and neck cancer: finding a practical segmentation method.

PURPOSE: Although metabolic tumor volume (MTV) and total lesion glycolysis (TLG) have shown good prognostic value in head and neck cancer (HNC), there are still many issues to resolve before their potential application in standard clinical practice. The purpose of this study was to compare the discrimination ability of two relevant segmentation methods in HNC and to evaluate the potential benefit of adding lymph nodes' metabolism (LNM) to the measurements. METHODS: We retrospectively analyzed a recently published database of 62 patients with HNC treated with chemoradiotherapy. MTV and TLG were measured using an absolute threshold of SUV2.5. Comparison analysis with previously published background-level threshold (BLT) results was done through Concordance index (C-index) in eight prognostic models. RESULTS: BLT obtained better C-index values in five out of the eight models. The addition of LNM improved C-index values in six of the prognostic models. CONCLUSION: We found a potential benefit in adding LNM to the main tumor measurements, as well as in using a BLT for MTV segmentation compared to the most commonly used SUV2.5 threshold. Despite its limitations, this study suggests a practical and simple manner to use these parameters in standard clinical practice, aiming to help elaborate a general consensus.

Tuning the donor-acceptor interactions in phase-segregated block molecules.

The assembly of donor-acceptor molecules via charge transfer (CT) interactions gives rise to highly ordered nanomaterials with appealing electronic properties. Here, we present the synthesis and bulk co-assembly of pyrene (Pyr) and naphthalenediimide (NDI) functionalized oligodimethylsiloxanes (oDMS) of discrete length. We tune the donor-acceptor interactions by connecting the pyrene and NDI to the same oligomer, forming a heterotelechelic block molecule (NDI-oDMSPyr), and to two separate oligomers, giving Pyr and NDI homotelechelic block molecules (Pyr-oDMS and NDI-oDMS). Liquid crystalline materials are obtained for binary mixtures of Pyr-oDMS and NDI-oDMS, while crystallization of the CT dimers occurred for the heterotelechelic NDI-oDMS-Pyr block molecule. The synergy between crystallization and phase-segregation coupled with the discrete length of the oDMS units allows for perfect order and sharp interfaces between the insulating siloxane and CT layers composed of crystalline CT dimers. We were able to tune the lamellar domain spacing and donor-acceptor CT interactions by applying pressures up to 6 GPa on the material, making the system promising for soft-material nanotechnologies. These results demonstrate the importance of the molecular design to tune the CT interactions and stability of a CT material.

SARS-CoV-2 in eight municipalities of the Colombian tropics: high immunity, clinical and sociodemographic outcomes.

BACKGROUND: Serological evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an alternative that allows us to determine the prevalence and dynamics of this infection in populations. The goal of this study was to determine the clinical and sociodemographic dynamics of SARS-CoV-2 infection in a region of the Colombian Caribbean. METHODS: Between July and November 2020, a cross-sectional observational study was carried out in Córdoba, located in northeast Colombia in the Caribbean area. Eight municipalities with the largest populations were chosen and 2564 blood samples were taken. A commercial enzyme-linked immunosorbent assay was used with the recombinant protein antigen N of SARS-CoV-2. The people included in the study were asked for sociodemographic and clinical data, which were analysed by statistical methods. RESULTS: A seroprevalence of 40.8% was obtained for SARS-CoV-2 in the Córdoba region. In the bivariate analysis, no differences were observed in seropositivity against SARS-CoV-2 for gender or age range (p>0.05). Higher seropositivity was found in low socio-economic status and symptomatic patients (p<0.0001). A total of 30.7% of the asymptomatic patients were seropositive for SARS-CoV-2, which could be linked to the spread of this infection. In the multivariate analysis, seroconversion was related to poverty and clinical manifestations such as anosmia and ageusia (p<0.05). CONCLUSIONS: The high seropositivity in Córdoba is due to widespread SARS-CoV-2 in this population. The relationship between seropositivity and socio-economic status suggests a higher exposure risk to the virus caused by informal economic activities in low-income groups. Clinical manifestations such as anosmia and ageusia could be clinical predictors of infection by the new emergent coronavirus.

Heterolytic Bond Cleavage in a Scissile Triarylmethane Mechanophore.

Covalent mechanophores display the cleavage of a weak covalent bond when a sufficiently high mechanical force is applied. Three different covalent bond breaking mechanisms have been documented thus far, including concerted, homolytic, and heterolytic scission. Motifs that display heterolytic cleavage typically separate according to non-scissile reaction pathways that afford zwitterions. Here, we report a new mechanochromic triarylmethane mechanophore, which dissociates according to a scissile heterolytic pathway and displays a pronounced mechanochromic response. The mechanophore was equipped with two styrenylic handles that allowed its incorporation as a cross-linker into poly(N,N-dimethylacrylamide) and poly(methyl acrylate-co-2-hydroxyethyl acrylate) networks. These materials are originally colorless, but compression or tensile deformation renders the materials colored. By combining tensile testing and in situ transmittance measurements, we show that this effect is related to scissile cleavage leading to colored triarylmethane carbocations.

Adding value to tumor staging in head and neck cancer: The role of metabolic parameters as prognostic factors.

BACKGROUND: Validated biomarkers in head and neck squamous cell carcinoma (HNSCC) are scarce. METHODS: We retrospectively analyzed 62 patients with HNSCC treated with radiotherapy +/- concurrent chemotherapy. Pretreatment metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured in a 18 F-FDG positron emission tomography using a liver dependent standardized uptake value threshold. Cox regression analyses were performed to find associations with disease-free survival (DFS) and overall survival (OS). RESULTS: High values of MTV (>37 ml) were independently associated with a worse DFS (hazard ratio [HR] = 3.45; 95% confidence interval [CI], 1.52-7.84) and OS (HR = 3.27; 95% CI, 1.41-7.57). Similar results were found for high values of TLG (>247 g) for DFS (HR = 3.32; 95% CI, 1.44-7.65) and OS (HR = 3.42; 95% CI, 1.45-8.07). CONCLUSIONS: MTV and TLG can be considered as independent prognostic factors for DFS and OS in patients with HNSCC. Considering how easily obtainable they are, they may be useful for predicting clinical outcomes in these patients.

Tuning of Morphology by Chirality in Self-Assembled Structures of Bis(Urea) Amphiphiles in Water.

We present the synthesis and self-assembly of a chiral bis(urea) amphiphile and show that chirality offers a remarkable level of control towards different morphologies. Upon self-assembly in water, the molecular-scale chiral information is translated to the mesoscopic level. Both enantiomers of the amphiphile self-assemble into chiral twisted ribbons with opposite handedness, as supported by Cryo-TEM and circular dichroism (CD) measurements. The system presents thermo-responsive aggregation behavior and combined transmittance measurements, temperature-dependent UV, CD, TEM, and micro-differential scanning calorimetry (DSC) show that a ribbon-to-vesicles transition occurs upon heating. Remarkably, chirality allows easy control of morphology as the self-assembly into distinct aggregates can be tuned by varying the enantiomeric excess of the amphiphile, giving access to flat sheets, helical ribbons, and twisted ribbons.

Stepwise Adsorption of Alkoxy-Pyrene Derivatives onto a Lamellar, Non-Porous Naphthalenediimide-Template on HOPG.

The development of new strategies for the preparation of multicomponent supramolecular assemblies is a major challenge on the road to complex functional molecular systems. Here we present the use of a non-porous self-assembled monolayer from uC33 -NDI-uC33 , a naphthalenediimide symmetrically functionalized with unsaturated 33 carbon-atom-chains, to prepare bicomponent supramolecular surface systems with a series of alkoxy-pyrene (PyrOR) derivatives at the liquid/HOPG interface. While previous attempts at directly depositing many of these PyrOR units at the liquid/HOPG interface failed, the multicomponent approach through the uC33 -NDI-uC33 template enabled control over molecular interactions and facilitated adsorption. The PyrOR deposition restructured the initial uC33 -NDI-uC33 monolayer, causing an expansion in two dimensions to accommodate the guests. As far as we know, this represents the first example of a non-porous or non-metal complex-bearing monolayer that allows the stepwise formation of multicomponent supramolecular architectures on surfaces.

Discordant Supramolecular Fibres Reversibly Depolymerised by Temperature and Light.

Synthetic stimuli responsive supramolecular polymers attract increasing interest for their ability to mimic the unique properties of natural assemblies. Here we focus on the well-studied benzene-1,3,5-tricarboxamide (BTA) motif, and substitute it with two (S)-3,7-dimethyloctyl groups and an azobenzene photoswitch. We demonstrate the UV (λ=365 nm) induced depolymerisation of the helical hydrogen-bonded polymers in methylcyclohexane (MCH) through circular dichroism and UV-vis spectroscopy in dilute solution (15 µm), and NMR and iPAINT super-resolution microscopy in concentrated solution (300 µm). The superstructure can be regenerated after thermal depolymerization, whilst repeated depolymerisation can be reversed without degradation by irradiating at λ=455 nm. Molecular dynamics simulations show that the most energetically favourable configuration for these polymers in MCH is a left-handed helical network of hydrogen-bonds between the BTA cores surrounded by two right-handed helices of azobenzenes. The responsiveness to two orthogonal triggers across a broad concentration range holds promise for use in, for example, photo-responsive gelation.

Cerebellar gangliocytoma as a cause of fluctuating hearing loss.

Cerebellar lesions could be a cause of fluctuating hearing loss, due to the increase of intracranial pressure by partially or complete blocking of the Foramen of Luschka. Patients with intracranial hypertension may present audio-vestibular symptoms. Fluctuating sensorineural hearing loss may be the manifestation of different inner ear disorders such as Meniere's disease (MD), immune-mediated inner ear disease (IMIED), otosyphilis, and labyrinthine fistula including semicircular canal dehiscence. A rare mechanism involved in the fluctuating hearing loss is the increase in cerebrospinal fluid (CSF) pressure, that may be caused by a cerebellar tumor. A 51-year-old female presented a 2-year history of left ear fluctuating hearing loss and tinnitus, with fluctuations among the day, and normal otoscopy. Several audiometries showed a left ear moderate sensorineural hearing loss in low frequencies (Figure 1). The patient underwent a cerebral magnetic resonance imaging (MRI) (Figure 2). She was treated with three courses of systemic steroids showing improvement of symptoms during the treatment. However, the symptoms always returned when corticotherapy was interrupted. The patient was given two intratympanic steroids cycles combined with hydrochlorothiazide/ amiloride hydrochloride. The cerebral MRI described a left cerebellar focal lesion diagnosed as a cerebellar gangliocytoma. After receiving the second intratympanic steroids, cycle combined with systemic ameride showed a significant improvement of audition. Between the several causes of fluctuating hearing loss, a cerebellar gangliocytoma is a very rare disease, which needs a high degree of suspicion and otorhinolaryngologists should be familiar with this entity since patients may present with audiological and vestibular symptoms.