New Insights on Solvent-Induced Changes in Refractivity and Specific Rotation of Poly(propylene oxide) Systems Extracted from Channeled Spectra

Investigation of chiroptical polymers in the solution phase is paramount for designing supramolecular architectures for photonic or biomedical devices. This work is devoted to the case study of poly(propylene oxide) (PPO) optical activity in several solvents: benzonitrile, carbon disulfide, chloroform, ethyl acetate, and p-dioxane. To attain information on the interactions in these systems, rheological testing was undertaken, showing distinct variations of the rheological parameters as a function of the solvent type. These aspects are also reflected in the refractive index dispersive behavior, from which linear and non-linear optical properties are extracted. To determine the circular birefringence and specific rotation of the PPO solutions, the alternative method of the channeled spectra was employed. The spectral data were correlated with the molecular modeling of the PPO structural unit in the selected solvents. Density functional theory (DFT) computational data indicated that the torsional potential energy-related to the O1-C2-C3-O4 dihedral angle from the polymer repeating unit-was hindered in solvation environments characterized by high polarity and the ability to interact via hydrogen bonding. This was in agreement with the optical characterization of the samples, which indicated a lower circular birefringence and specific rotation for the solutions of PPO in ethyl acetate and p-dioxane. Also, the shape of optical rotatory dispersion curves was slightly modified for PPO in these solvents compared with the other ones.

Study on cellulose nanofibrils/copolymacrolactone based nano-composites with hydrophobic behaviour, self-healing ability and antioxidant activity

The multiple uses of cellulose nanofibrils (CNFs) originate from their availability from renewable resources, and are due to their physico-chemical properties, biodegradability and biocompatibility. At the same time, reducing sensitivity to humidity, increasing interfacial adhesion and hydrophobic modification of the CNF surface to diversify applications and improve operation, are current targets pursued. This study focuses on the preparation of a novel gel structure using cellulose nanofibrils (CNFs) and poly(ethylene brassylate-co-squaric acid) (PEBSA50/50), a bio-based copolymacrolactone. The primary goal is to achieve the gel with reduced sensitivity to humidity and enhanced hydrophobic behaviour. The new system was characterized in comparison to its constituent components using various techniques, such as Fourier transform infrared spectroscopy, thermal analysis, X-ray diffraction, and NIR - chemical imaging. Rheological tests demonstrated the formation of the CNF_PEBSA50/50 gel as a result of physical interactions between the two polymeric partners and revealed self-healing abilities for the prepared gels. Determination of the contact angle, surface free energy, as well as dynamic measurements of the vapour sorption of the CNF_PEBSA50/50 system, confirmed the achievement of the study's aim. Furthermore, the CNF_PEBSA50/50 network was utilized to encapsulate citric acid, resulting in the creation of a new bioactive composite with both antioxidant and antimicrobial activity.

Bioactive Composite Cryogels Based on Poly (Vinyl Alcohol) and a Polymacrolactone as Tissue Engineering Scaffolds: In Vitro and In Vivo Studies

In light of the increasing resistance of pathogenic microorganisms to the action of antibiotics, essential oils extracted from plants with therapeutic activity provide a significant alternative to obtaining dressings for the treatment of skin wounds. The encapsulation of essential oils in an amphiphilic gel network allows better dispersion and preservation of hydrophobic bioactive substances while promoting their prolonged release. In this study, we focused on the development of a poly (vinyl alcohol) (PVA)/poly (ethylene brassylate-co-squaric acid) (PEBSA) platform embedded with thymol (Thy), and α-tocopherol (α-Tcp) as a co-drug structure with prospective use for the treatment and healing of skin wounds. The new complex bioactive system was prepared through repeated freeze-thaw processes. The influence of the composition on surface topography, hydrophilic/hydrophobic character, and in vitro interaction with simulated body fluids was evidenced. BALB/3T3 fibroblast cell culture demonstrated the cryogel scaffolds' cytocompatibility. Tests on Wistar rats confirmed their biocompatibility, integration with host tissue, and the absence of inflammatory processes. The bioactive compound significantly enhanced the healing process of full-thickness excision wounds in a rat model. Further investigations on in vivo infection models would assess the potential of the PVA/PEBSA platform with dual bioactive activity for clinical antimicrobial and wound healing therapy.

Morphological Evaluation of Supramolecular Soft Materials Obtained through Co-Assembly Processes

Low-molecular-weight gelators (LMWGs) are compounds with an intrinsic tendency to self-assemble forming various supramolecular architectures via non-covalent interactions. Considering that the development of supramolecular assemblies through the synergy of molecules is not entirely understood at the molecular level, this study introduced a Fmoc-short peptide and four Fmoc-amino acids as building blocks for the self-assembly/co-assembly process. Hence, we investigated the formation of supramolecular gels starting from the molecular aggregation following two triggering approaches: solvent/co-solvent method and pH switch. The complex morphological analysis (POM, AFM, and STEM) offered an insight into the spontaneous formation of well-ordered nanoaggregates. Briefly, POM and AFM images demonstrated that self-assembled gels present various morphologies like dendrimer, spherulite, and vesicle, whereas all co-assembled supramolecular systems exhibit fibrillar morphologies as a result of the interaction between co-partners of each system. STEM study has confirmed that the molecules interact and join together, finally forming a fibrous network, an aspect seen in both self-assembled and co-assembled gels. XRD allowed the determination of the molecular arrangement. The study emphasized that the Fmoc motif protected the amino groups and facilitated gelation through additional π-π interactions.

Testing the Performance of the Azo-Polyimide Supramolecular Systems as Substrate for Sensors Based on Platinum Electrodes

Azo-polyimide films with supramolecular structure were obtained by casting onto glass plates a mixture based on polyamidic acid and different quantities of azochromophore, followed by thermal treatment to realize the final azo-polyimide structure. The dielectric characteristics of the supramolecular structure of polymer films were investigated by broad-band dielectric spectroscopy measurements at different temperatures and frequencies. The free-standing films proved to be flexible and tough and maintained their integrity after repeated bending. The work of adhesion at the polymer/platinum interface was calculated after the evaluation of the surface energy parameters before and after plasma treatment. Atomic force microscopy was used to image the surface morphology, the evolution of the roughness parameters, and the adhesion force between the platinum-covered tip and the polymer surface, registered at the nanoscale with the quantity of the azo dye introduced in the system. The simulation of the columnar growth of a platinum layer was made to provide information about the deposition parameters that should be used for optimal results in the deposition of platinum electrodes for sensors.

Atomic Force Microscopy Probing and Analysis of Polyimide Supramolecular Systems for Sensor Devices

A series of polyimide supramolecular systems containing different amounts of azochromophore were tested as flexible supports that can be used in the fabrication of certain devices, such as sensors for monitoring the temperature changes, by coating them with conductive metals. That is why it is required to have good interfacial compatibility between the flexible substrate and the inorganic layer. The interface of the sensor elements must be designed in such a way as to improve the sensitivity, accuracy, and response time of the device. Laser irradiation is one of the commonly employed techniques used for surface adaptation by patterning polyimides to increase contact and enhance device reliability and signal transmission. In this context, this work highlights unreported aspects arising from the azo-polyimide morphology, local nanomechanical properties and wettability, which are impacting the compatibility with silver. The texture parameters indicate an improvement of the modulations' quality arising after laser irradiation through the phase mask, increasing the bearing capacity, fluid retention, and surface anisotropy when the amount of the azochromophore increases. The force curve spectroscopy and wettability studies indicated that the modification of the polymer morphology and surface chemistry lead to a better interfacial interaction with the metal lines when the azo component and the polyamidic acid are in equimolar quantities.

Review on Optical Methods Used to Characterize the Linear Birefringence of Polymer Materials for Various Applications

Optical polymers are recognized for their high transparency, raised flexibility, low cost, and good film-forming ability; hence, they introduce a multitude of benefits in a wide range of devices, such as information storage, displays, optical communications, and filters. Among the optical properties, birefringence is an essential parameter in practical cases that demand the control of the state of polarization of light. This review is focused on describing some fundamental and applicative aspects concerning the optical birefringence of the polymer materials. First, elementary notions depicting the phenomenon of light double refraction in macromolecular media are provided. Furthermore, the most relevant optical techniques to determine birefringence are reviewed by highlighting the working principle and mathematical basis for computing this parameter. Then, a series of investigations of optically birefringent polymers are described, summarizing the most utilized approaches to induce light double refraction in such materials. The selected results are analyzed in relation to the pursued applications. In the end, the future of this scientific domain is briefly presented by establishing the research paths that need further exploration. Moreover, the novel directions that could be formulated and might contribute to certain considerable advancements in the materials employed in the modern optical technologies are mentioned.

Bioactive Materials Based on Hydroxypropyl Methylcellulose and Silver Nanoparticles: Structural-Morphological Characterization and Antimicrobial Testing

The progress achieved in recent years in the biomedical field justifies the objective evaluation of new techniques and materials obtained by using silver in different forms as metallic silver, silver salts, and nanoparticles. Thus, the antibacterial, antiviral, antifungal, antioxidant, and anti-inflammatory activity of silver nanoparticles (AgNPs) confers to newly obtained materials characteristics that make them ideal candidates in a wide spectrum of applications. In the present study, the use of hydroxypropyl methyl cellulose (HPMC) in the new formulation, by embedding AgNPs with antibacterial activity, using poly(N-vinylpyrrolidone) (PVP) as a stabilizing agent was investigated. AgNPs were incorporated in HPMC solutions, by thermal reduction of silver ions to silver nanoparticles, using PVP as a stabilizer; a technique that ensures the efficiency and selectivity of the obtained materials. The rheological properties, morphology, in vitro antimicrobial activity, and stability/catching of Ag nanoparticles in resulting HPMC/PVP-AgNPs materials were evaluated. The obtained rheological parameters highlight the multifunctional roles of PVP, focusing on the stabilizing effect of new formulations but also the optimization of some properties of the studied materials. The silver amount was quantified using the spectroscopy techniques (energy-dispersive X-ray fluorescence (XRF), energy-dispersive X-ray spectroscopy (EDX)), while formation of the AgNPs was confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Also, the morphological examination (Atomic Force Microscopy (AFM) and Scanning electron microscopy (SEM)) by means of the texture roughness parameters has evidenced favorable characteristics for targeted applications. Antibacterial activity was tested against Escherichia coli and Staphylococcus aureus and was found to be substantially improved was silver was added in the studied systems.

Etiology Of Neonatal Burns: A Systematic Review

Burns in neonates are a rare pathology with a significant impact on the patient, the family and the healthcare system. At present, scarce information exists on the etiology of this type of injury. A comprehensive worldwide literature review of all publications, including our personal case series, was conducted in order to analyse the etiology of neonatal burns and summarize the available evidence. A total of 41 publications were identified in the last 4 decades, comprising of 105 cases from 20 countries, thus confirming that neonatal burns are, indeed, a rare pathology. All types of burns were recorded in neonates, the most frequent being contact burns, followed by flames and scalds. Almost 60% of burns occurred in a hospital setting due to human factors, malfunctioning devices, or hospital infrastructure deficiency. Compared to domestic burns, iatrogenic injuries occurred at an earlier age (5.4±9.1 days vs. 15.7±9.8 days, p<0.0001) and in neonates with significantly smaller weights (2102.7±1350g vs. 3197±300.8g, p<0.0001). The number of cases was almost equally distributed between developed and developing countries, but developed countries were characterised by a significantly higher preponderance of iatrogenic burns, while in developing countries domestic burns were more frequent (p<0.0001). We believe that this systematic review outlines the potential causes of neonatal burns and provides essential information for formulating prevention strategies.

Polyimide Layers with High Refractivity and Surface Wettability Adapted for Lowering Optical Losses in Solar Cells

The performance of photovoltaics with superstrate configuration is limited by the rigidity and low refractivity of a classical glass cover. In this work, two polyimides (PIs) and two copolyimides combined in the main chain cycloaliphatic moieties, aromatic sequences, chalcogen atoms, and having/lacking fluorine atoms, are proposed as shielding covers for solar cells. The samples containing small cycloaliphatic moieties displayed high transmittance above 80% at 550 nm. The refractive index values under changeable wavelengths and temperatures were shown to influence the magnitude of the reflection losses. At the sample interface with the transparent electrode, optical losses were reduced (~0.26%) in comparison to the classical glass (~0.97%). The samples with the best optical features were further subjected to a surface treatment to render the self-cleaning ability. For this, a new approach was used residing in irradiation with the diffuse coplanar surface barrier discharge (DCSBD), followed by spraying with a commercial substance. Scanning electron microscopy and atomic force microscopy scans show that the surface characteristics were changed after surface treatment, as indicated by the variations in root mean square roughness, surface area ratio, and surface bearing index values. The proposed PI covers diminish the optical losses caused by total internal reflection and soiling, owing to their adapted refractivity and superhydrophobic surfaces (contact angles > 150°), and open up new perspectives for modern photovoltaic technologies.

A New Texturing Approach of a Polyimide Shielding Cover for Enhanced Light Propagation in Photovoltaic Devices

The efficiency of photovoltaics (PVs) is related to cover material properties and light management in upper layers of the device. This article investigates new polyimide (PI) covers for PVs that enable light trapping through their induced surface texture. The latter is attained via a novel strategy that involves multi-directional rubbing followed by plasma exposure. Atomic force microscopy (AFM) is utilized to clarify the outcome of the proposed light-trapping approach. Since a deep clarification of either random or periodic surface morphology is responsible for the desired light capturing in solar cells, the elaborated texturing procedure generates a balance among both discussed aspects. Multidirectional surface abrasion with sand paper on pre-defined directions of the PI films reveals some relevant modifications regarding both surface morphology and the resulted degree of anisotropy. The illuminance experiments are performed to examine if the created surface texture is suitable for proper light propagation through the studied PI covers. The adhesion among the upper layers of the PV, namely the PI and transparent electrode, is evaluated. The correlation between the results of these analyses helps to identify not only adequate polymer shielding materials, but also to understand the chemical structure response to new design routes for light-trapping, which might significantly contribute to an enhanced conversion efficiency of the PV devices.

Neonatal Burns - A Romanian Experience From A Tertiary Care Burn Unit

Burns in neonates is a unique pathology that poses management challenges, as, besides treating the burn injury, the medical team needs to be familiar with the unique physiology of the newborn. This study aimed to review our center's experience with the management of neonatal burns. A 7-year retrospective study of neonatal burns managed at a tertiary national referral unit in Bucharest, Romania, was performed. Patients were divided into two groups, preterm and term, based on gestational age. Collected data included demographics, treatment, complications and follow-up. Our center managed 13 neonates with burns (5 term and 8 preterm), with a mean age at injury of 8.6 days. All neonatal burns were thermal injuries. For preterm babies, all burns were iatrogenic, consisting of victims of a fire in a Maternity Hospital, while for the term group only one was iatrogenic. Burns were more extensive in the premature group (65% vs. 20% mean TBSA, p=0.0001). All premature patients had associated inhalation injuries. Surgical treatment was indicated for two term patients. Survival rate was 77% and was negatively influenced by inhalation injury, burn shock and TBSA >50%. In conclusion, the majority of hospitalized neonatal burns in Romania were the result of a fire disaster secondary to an infrastructure deficiency. Their management is complex, posing specific challenges, and needs to be led by a multidisciplinary team that can ensure an individualized continuum of acute burn care and recovery.

Synthesis of Poly(Ethylene Brassylate-Co-squaric Acid) as Potential Essential Oil Carrier

Bio-based compounds are a leading direction in the context of the increased demand for these materials due to the numerous advantages associated with their use over conventional materials, which hardly degrade in the environment. At the same time, the use of essential oils and their components is generated mainly by finding alternative solutions to antibiotics and synthetic preservatives due to their bioactive characteristics, but also to their synergistic capacity during the manifestation of different biological properties. The present study is devoted to poly(ethylene brassylate-co-squaric acid) (PEBSA), synthesis and its use for thymol encapsulation and antibacterial system formation. The synthesized copolymer, performed through ethylene brassylate macrolactone ring-opening and copolymerization with squaric acid, was physicochemical characterized. Its amphiphilic character allowed the entrapment of thymol (Ty), a natural monoterpenoid phenol found in oil of thyme, a compound with strong antiseptic properties. The copolymer chemical structure was confirmed by spectroscopic analyses. Thermal analysis evidenced a good thermal stability for the copolymer. Additionally, the antimicrobial activity of PEBSA_Ty complex was investigated against eight different reference strains namely: bacterial strains-Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Enterococcus faecalis ATCC 29212, Klebsiella pneumonie ATCC 10031 and Salmonella typhimurium ATCC 14028, yeast strains represented by Candida albicans ATCC10231 and Candida glabrata ATCC 2001, and the fungal strain Aspergillus brasiliensis ATCC9642.

Evaluation of Local Mechanical and Chemical Properties via AFM as a Tool for Understanding the Formation Mechanism of Pulsed UV Laser-Nanoinduced Patterns on Azo-Naphthalene-Based Polyimide Films

Aromatic polyimides containing side azo-naphthalene groups have been investigated regarding their capacity of generating surface relief gratings (SRGs) under pulsed UV laser irradiation through phase masks, using different fluencies and pulse numbers. The process of the material photo-fluidization and the supramolecular re-organization of the surface were investigated using atomic force microscopy (AFM). At first, an AFM nanoscale topographical analysis of the induced SRGs was performed in terms of morphology and tridimensional amplitude, spatial, hybrid, and functional parameters. Afterward, a nanomechanical characterization of SRGs using an advanced method, namely, AFM PinPoint mode, was performed, where the quantitative nanomechanical properties (i.e., modulus, adhesion, deformation) of the nanostructured azo-polyimide surfaces were acquired with a highly correlated topographic registration. This method proved to be very effective in understanding the formation mechanism of the surface modulations during pulsed UV laser irradiation. Additionally to AFM investigations, confocal Raman measurements and molecular simulations were performed to provide information about structured azo-polyimide chemical composition and macromolecular conformation induced by laser irradiation.

Xanthogranulomatous pyelonephritis in a paediatric cohort (1963-2016): Outcomes from a large single-center series

BACKGROUND

Xanthogranulomatous pyelonephritis (XGP) is an uncommon chronic destructive granulomatous inflammation of the kidney. It was first described in 1916, and is thought to affect 6/1000 cases of pyelonephritis. Its manifestations are varied, and with a limited number of cases in the literature, the optimal diagnosis and management of XGP in the paediatric cohort is still unknown.

MATERIAL AND METHODS

The medical records of children who were diagnosed and treated for XGP at the current unit during the period 1963-2016, inclusive, were retrospectively reviewed. Information pertaining to each patient was recorded, including: demographic data, past medical history, clinical and biochemical characteristics, diagnostic procedures, treatment methods, histopathologic diagnosis of the removed specimen, and outcome.

RESULTS

A total of 66 children with a median age of 4.84 years (range 1.1-14.81), with an M:F ratio 1.35:1 underwent nephrectomy for XGP and had a median follow-up of 7.19 years (range 0.11-17.45). The most common presentations were systemic illness (62.1%), pain (60.6%), urinary tract infections (54.5%) and an abdominal mass (39.4%); pyrexia was present in 53%. Biochemical abnormalities included anaemia (86.3%), thrombocytosis (80.3%) and hypomagnesemia (65.1%). There was an 83.3% concordance between intraoperative cultures and positive mid-stream urines. Index kidneys were significantly larger than the contralateral side (mean 1.32 cm; P = 0.002). Staging of XGP demonstrated extension beyond the kidney in 79% of kidneys. Computed tomography (CT) was performed in 11 cases (Summary figure). Dimercaptosuccinic acid (DMSA) scan showed 0-10% function in 90.47% of cases. Surgical procedures included nephrectomy (n = 63) and partial nephrectomy (n = 3). Perioperative complications included colonic resections (n = 5) and abscess formation in 18%.

CONCLUSIONS

This is the largest series to date of XGP in a paediatric cohort. XGP should be included in the differential diagnosis of all children presenting with perirenal or psoas abscesses, renal masses and/or non-functioning kidneys with/or without associated urolithiasis. Clinical awareness and a high index of suspicion is required to achieve the correct pre-operative diagnosis and appropriate management.

Establishing proper scanning conditions in atomic force microscopy on polyimide and polyurethane samples and their effect on 3D surface texture parameters

Several atomic force microscopy (AFM) tests have been carried out on both smooth (polyimide) and rough (polyurethane) surfaces so that to obtain the best results; subsequently, the optimization of experiments performed is presented. A special emphasis has been put on the effect of tip geometry, image pre-processing procedure, scanning area, resolution, pixel size, and cantilever oscillation amplitude in tapping mode, as well as on the quality of the topographical images and 3D surface texture parameters. After viewing the scanning tip and finding out its sharpness, degradation, and contamination, a simultaneous calibration in X, Y, and Z directions, lateral calibration of SPM scanners and detection of lateral non-linearity, hysteresis, creep, and cross-coupling effects has been made. We have established the following experimental parameters: proper scanning resolution (512 × 512 pixels), adequate pixel size (between 2.9 and 19.5 nm) and suitable intermittent contact region (moderate tapping) for which the AFM images present good contrast and resolution. Using these parameters, the values of 3D texture parameters remain constant. These kinds of measurements are extremely important to conduct further AFM experiments on polyimide and polyurethane surfaces under optimal conditions, thus avoiding unwanted artifacts on the morphological images or unrealistic values for the 3D surface texture parameters that might occur.

Electromechanical properties of polyimide composites containing titanium dioxide nanotubes

Polyimide composite films were prepared by casting solutions resulting from direct mixing of a poly(amic acid) and titanium dioxide (TiO2) nanotubes (TNTs) onto glass plates, followed by thermal imidization. TNTs with outer diameters of approximately 10–12 nm and length of several hundreds of nanometers were synthesized by the hydrothermal method. The morphology of the nanotubes was investigated by using high-resolution transmission electron microscopy. The influence of TNTs content on structural, thermal, and electromechanical properties of pure polyimide and composite films was studied. The scanning electron microscopy and atomic force microscopy showed good compatibility between TNTs filler and polyimide matrix. The value of average roughness of film surface increases with increasing the content of TNTs. The films were flexible, tough, and exhibited high thermal stability. A study of microelectromechanical properties of these films was performed. The films showed nanometric displacements in the range of 250–800 nm when an electric voltage of 500 V was applied on their surface.

THE ROLE OF IMAGISTIC INVESTIGATIONS IN DIAGNOSING ACUTE COMPLICATED DIVERTICULITIS

Recent progress in medical imaging allowed higher accuracy in diagnosis of acute diverticulitis. Contrast enhanced Computed Tomography (CT) has a high sensitivity and specificity, reaching a diagnostic accuracy over 95%. Although abdominal X-ray and ultrasonography are still used, their utility is limited in this pathology. Retrospective study including patients admitted for acute diverticulitis in the Surgery Clinic of Bucharest Clinical Emergency Hospital between January 2012 and July 2014. From the total number of 29508 admissions, 156 patients were diagnosed with acute diverticulitis staged Hinchey I to IV. The imagistic investigations on admission were plain abdominal X-ray (128 cases), which identified 6 cases of pneumoperitoneum; abdominal ultrasound (112 cases) which identified colonic wall thickening and/or free peritoneal fluid in 29.4% cases. Contrast enhanced CT was performed in 97 cases, successfully establishing the diagnostic in 80% of cases. The mean waiting time interval until CT scan was under 24 hours for the patients with acute complicated diverticulitis. Patients with acute diverticulitis staged Hinchey II-III needed CT reevaluation both for monitoring the response to conservative treatment and identification of postoperative complications. Due to its high diagnostic accuracy and short waiting interval, in the studied cohort, contrast enhanced CT represents the investigation of choice in diagnosing acute diverticulitis. Abdominal ultrasound remains an alternative only in cases where CT scan is unavailable or contraindicated, having a lower accuracy in diagnosis and evaluation of diverticular disease complications.

Properties of some azo-copolyimide thin films used in the formation of photoinduced surface relief gratings

The patterning of the free standing azo-copolyimide films under different irradiation conditions led to the uniform surface relief gratings.

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

We report on the synthesis as well as the optical, electrochemical and morphological properties of two polyrotaxanes (4a and 4b), which consist of electron-accepting 9,9-dicyanomethylenefluorene 1 as an inclusion complex in persilylated β- or γ-cyclodextrin (TMS-β-CD, TMS-γ-CD) (1a, 1b) and methyltriphenylamine as an electron-donating molecule. They are statistically distributed into the conjugated chains of 9,9-dioctylfluorene 3 and compared with those of the corresponding non-rotaxane 4 counterpart. Rotaxane formation results in improvements of the solubility, the thermal stability, and the photophysical properties. Polyrotaxanes 4a and 4b exhibited slightly red-shifted absorption bands with respect to the non-rotaxane 4 counterpart. The fluorescence lifetimes of polyrotaxanes follow a mono-exponential decay with a value of τ = 1.14 ns compared with the non-rotaxane, where a bi-exponential decay composed of a main component with a relative short time of τ₁ = 0.88 (57.08%) and a minor component with a longer lifetime of τ₂ = 1.56 ns (42.92%) were determined. The optical and electrochemical band gaps (ΔE_g) as well as the ionization potential and electronic affinity characterized by smaller values compared to the values of any of the constituents. AFM reveals that the film surface of 4a and 4b displays a granular morphology with a lower dispersity supported by a smaller roughness exponent compared with the non-rotaxane counterpart.

Difficulties in the diagnostics and treatment of near-total congenital megacolon

Near total colonic aganglionosis is one of the rarest forms of Hirschsprung's disease and until recent years it has been considered deadly. Establishing a correct diagnosis has proven to be challenging, because while the clinical and radiological features can be useful, they are not pathognomonic. Chronic intestinal obstruction and long-term parenteral nutrition dependency are associated with a high mortality risk for these patients. While there is no current consensus with regards to a superior operative method, the patients benefit from surgical techniques aimed at lengthening the intestine, as well as from intestine transplant. We report the case of a newborn baby girl who was admitted to our clinic for abdominal distension,biliary and fecaloid vomiting. With an initial suspicion of digestive tract malformation, the diagnosis of near total congenital megacolon was established with great difficulty and the infant underwent serial surgeries, ending up with an extended myotomy-myectomy (Ziegler's procedure) as a curative approach, with favorable immediate postoperative evolution.However, the patient developed sepsis and although the infection was treated accordingly, the baby's general condition kept deteriorating and exitus was recorded 77 days after admission.

Calcium carbonate microparticle templates using a PHOS-b-PMAA double hydrophilic copolymer

The crystallization characteristics of calcium carbonate microparticles grown from supersaturated aqueous solutions in the presence of a double hydrophilic block copolymer poly(p-hydroxystyrene-b-methacrylic acid), PHOS-b-PMAA, have been investigated. The studies aim to highlight both the possibilities and the limitations of CaCO3/PHOS-b-PMAA microparticle formation under different relative inorganic/polymer ratio conditions, varying the initial solution supersaturation or the polymer concentration. Scanning electron microscopy and atomic force microscopy were used to provide high-resolution images of particles and thereby information on the particle morphology, while X-ray diffraction analysis was used to determine the polymorph type and crystallite characteristics. The presence of the polymer in the composite particles was shown by thermogravimetric, particle charge density and zeta potential analysis. The polymer-induced sensitivity of the new composites to environmental pH variations has been followed by streaming potential variation.

Antifungal vanillin-imino-chitosan biodynameric films

Vanillin-chitosan biodynamers have been prepared and structure-morphology correlations revealed the pathway of progressive incorporation of the aldehyde onto chitosan backbones. Such dynamic biopolymers or biodynamers, generated from reversibly interacting components, offer the possibility to address the dynamic covalent behaviour of the reversible imine-bond formation/hydrolysis equilibria between vanillin and chitosan polymeric backbones. The reaction takes place with very low conversion in acidic aqueous solutions (7-12%), but the imine bond formation is amazingly improved (∼80%) when the reaction takes place while solution-solid state transition and solid state phase-organization events occur. The chitosan-vanillin biopolymeric films described here present interesting Candida albicans antifungal activity compared with other common bacterial strands, which suggests the implementation of these biocompatible materials as thin layer protecting systems for medical devices.

Associated type IIIB and type IV multiple intestinal atresia in a pediatric patient

Multiple intestinal atresia (MIA) is a complex congenital defect which represents a challenge for the pediatric surgeon,especially in the rare event of encountering type IIIb or apple peel atresia, which has a high mortality rate. The surgeon’s aim is to preserve as much bowel length as possible, to avoid postoperative sepsis and to prevent long-term complications such as short bowel syndrome. Access to a good neonatal intensive care unit and to parenteral nutritional support is crucial in the survival of these children. We report a rare case of multiple intestinal atresia associated with an apple peel atresia, which was managed by multiple intestinal resections and anastomosis without the placement of transanastomotic tubes or stomas.