Electrical Impedance Tomography-based Ventilation Patterns in Patients after Major Surgery.

Rationale: General anesthesia and mechanical ventilation have negative impacts on the respiratory system, causing heterogeneous distribution of lung aeration, but little is known about the ventilation patterns of postoperative patients and their association with clinical outcomes. Objectives: To clarify the phenotypes of ventilation patterns along a gravitational direction after surgery by using electrical impedance tomography (EIT) and to evaluate their association with postoperative pulmonary complications (PPCs) and other relevant clinical outcomes. Methods: Adult postoperative patients at high risk for PPCs, receiving mechanical ventilation on ICU admission (N = 128), were prospectively enrolled between November 18, 2021 and July 18, 2022. PPCs were prospectively scored until hospital discharge, and their association with phenotypes of ventilation patterns was studied. The secondary outcomes were the times to wean from mechanical ventilation and oxygen use and the length of ICU stay. Measurements and Main Results: Three phenotypes of ventilation patterns were revealed by EIT: phenotype 1 (32% [n = 41], a predominance of ventral ventilation), phenotype 2 (41% [n = 52], homogeneous ventilation), and phenotype 3 (27% [n = 35], a predominance of dorsal ventilation). The median PPC score was higher in phenotype 1 and phenotype 3 than in phenotype 2. The median time to wean from mechanical ventilation was longer in phenotype 1 versus phenotype 2. The median duration of ICU stay was longer in phenotype 1 versus phenotype 2. The median time to wean from oxygen use was longer in phenotype 1 and phenotype 3 than in phenotype 2. Conclusions: Inhomogeneous ventilation patterns revealed by EIT on ICU admission were associated with PPCs, delayed weaning from mechanical ventilation and oxygen use, and a longer ICU stay.

Future directions of lung-protective ventilation strategies in acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by the heterogeneous distribution of lung aeration along a gravitational direction due to increased lung density. Therefore, the lung available for ventilation is usually limited to ventral, nondependent lung regions and has been called the "baby" lung. In ARDS, ventilator-induced lung injury is known to occur in nondependent "baby" lungs, as ventilation is shifted to ventral, nondependent lung regions, increasing stress and strain. To protect this nondependent "baby" lung, the clinician targets and limits global parameters such as tidal volume and plateau pressure. In addition, positive end-expiratory pressure (PEEP) is used to prevent dorsal, dependent atelectasis and, if successful, increases the size of the baby lung and lessens its susceptibility to injury from inspiratory stretch. Although many clinical trials have been performed in patients with ARDS over the last two decades, there are few successfully showing benefits on mortality (ie, prone positioning and neuromuscular blocking agents). These disappointing results contrast with other medical disciplines, especially in oncology, where the heterogeneity of diseases is recognized widely and precision medicine has been promoted. Thus, lung-protective ventilation strategies need to take an innovative approach that accounts for the heterogeneity of injured lungs. This article summarizes ventilator-induced lung injury and ARDS and discusses how to implement precision medicine in the field of ARDS. Potentially useful methods to individualize PEEP with esophageal balloon manometry, lung recruitability, and electrical impedance tomography were discussed.

Experimental probing of dynamic self-organized columnar assemblies in colloidal liquid crystals.

Self-organized supramolecular assemblies are widespread in nature and technology in the form of liquid crystals, colloids, and gels. The reversible nature of non-covalent bonding leads to dynamic functions such as stimuli-responsive switching and self-healing, which are unachievable from an isolated molecule. However, multiple intermolecular interactions generate diverse conformational and configurational molecular motions over various time scales in their self-assembled states, and their specific dynamics remains unclear. In the present study, we have experimentally unveiled the static structures and dynamical behaviors in columnar colloidal liquid crystals by a coherent X-ray scattering technique using refined model samples. We have found that controlling the size distribution of the colloidal nanoplates dramatically changed their static and dynamic properties. Furthermore, the resulting dynamical behaviors obtained by X-ray photon correlation spectroscopy have been successfully decomposed into multiple distinct modes, allowing us to explore the dynamical origin in the colloidal liquid-crystalline state. The present approaches using a columnar liquid crystal may contribute to a better understanding of the dynamic nature of molecular assemblies and dense colloidal systems and bring valuable insights into rational design of functional properties of self-assembled materials such as stimuli-responsive liquid crystals, self-healing gels, and colloidal crystals. For these materials, the motion of constituent particles and molecules in the self-assembled state is a key factor for structural formation and dynamically responsive performance.

Factors Associated With Prolonged Ventilation in Patients Receiving Prone Positioning Protocol With Muscle Relaxants for Severe COVID-19 Pneumonia.

BACKGROUND: Prone positioning and neuromuscular blocking agents (NMBAs) are frequently used to treat severe respiratory failure from COVID-19 pneumonia. Prone positioning has shown to improve mortality, whereas NMBAs are used to prevent ventilator asynchrony and reduce patient self-inflicted lung injury. However, despite the use of lung-protective strategies, high death rates in this patient population have been reported. METHODS: We retrospectively examined the factors affecting prolonged mechanical ventilation in subjects receiving prone positioning plus muscle relaxants. The medical records of 170 patients were reviewed. Subjects were divided into 2 groups according to ventilator-free days (VFDs) at day 28. Whereas subjects with VFDs < 18 d were defined as prolonged mechanical ventilation, subjects with VFDs ≥18 d were defined as short-term mechanical ventilation. Subjects' baseline status, status at ICU admission, therapy before ICU admission, and treatment in the ICU were studied. RESULTS: Under the proning protocol for COVID-19, the mortality rate in our facility was 11.2%. The prognosis may be improved by avoiding lung injury in the early stages of mechanical ventilation. According to multifactorial logistic regression analysis, persistent SARS-CoV-2 viral shedding in blood (P = .03), higher daily corticosteroid use before ICU admission (P = .007), delayed recovery of lymphocyte count (P < .001), and higher maximal fibrinogen degradation products (P = .039) were associated with prolonged mechanical ventilation. A significant relationship was found between daily corticosteroid use before admission and VFDs by squared regression analysis (y = -0.00008522x2 + 0.01338x + 12.8; x: daily corticosteroids dosage before admission [prednisolone mg/d]; y: VFDs/28 d, R2 = 0.047, P = .02). The peak point of the regression curve was 13.4 d at 78.5 mg/d of the equivalent prednisolone dose, which corresponded to the longest VFDs. CONCLUSIONS: Persistent SARS-CoV-2 viral shedding in blood, high corticosteroid dose from the onset of symptoms to ICU admission, slow recovery of lymphocyte counts, and high levels of fibrinogen degradation products after admission were associated with prolonged mechanical ventilation in subjects with severe COVID-19 pneumonia.

Dynamic behaviours of epoxy resin thin films during the curing process.

Epoxy resin thin films are widely used in applications such as coating materials, insulator films, and adhesives; accordingly, investigations of their physical properties have garnered increasing importance. Although the physical properties of thermoset epoxy thin films are strongly affected by the curing conditions, such as the heating temperature and curing time, the dynamic properties during the curing process have not been studied thoroughly. In this study, we investigated the thermal fluctuations on the surface of epoxy resin thin films using grazing-incidence X-ray photon correlation spectroscopy, to elucidate the dynamic behaviours during the curing process. We thus succeeded in observing the freezing of capillary waves during the thermal curing process. These results are expected to facilitate a deeper understanding of the curing mechanisms of various thin films.

Control of blood glucose levels by an artificial pancreas in patients with severe coronavirus disease 2019 pneumonia.

BACKGROUND: Many patients with severe coronavirus disease 2019 (COVID-19) pneumonia experience hyperglycemia. It is often difficult to control blood glucose (BG) levels in such patients using standard intravenous insulin infusion therapy. Therefore, we used an artificial pancreas. This study aimed to compare the BG status of the artificial pancreas with that of standard therapy. METHODS: Fifteen patients were included in the study. BG values and the infusion speed of insulin and glucose by the artificial pancreas were collected. Arterial BG and administration rates of insulin, parenteral sugar, and enteral sugar were recorded during the artificial pancreas and standard therapy. The target BG level was 200 mg/dl. RESULTS: Arterial BG was highly correlated with BG data from the artificial pancreas. A higher BG slightly increased the difference between the BG data from the artificial pancreas and arterial BS. No significant difference in arterial BG was observed between the artificial pancreas and standard therapy. However, the standard deviation with the artificial pancreas was smaller than that under standard therapy (p < 0.0001). More points within the target BG range were achieved with the artificial pancreas (180-220 mg/dl) than under standard therapy. The hyperglycemic index of the artificial pancreas (8.7 ± 15.6 mg/dl) was lower than that of standard therapy (16.0 ± 21.5 mg/dl) (p = 0.0387). No incidence of hypoglycemia occurred under the artificial pancreas. CONCLUSIONS: The rate of achieving target BG was higher using artificial pancreas than with standard therapy. An artificial pancreas helps to control BG in critically ill patients.

[Endobronchial Lipomatous Hamartoma Extended beyond a Bronchial Wall:Report of a Case].

Pulmonary hamartomas are common benign lung tumors. Most cases are parenchymal chondromatous hamartomas, whereas endobronchial lipomatous hamartomas are rarely encountered. A 78-year-old man was referred for left superior subsegmental atelectasis due to obstruction by an endobronchial tumor that was found incidentally on chest computed tomography for the postoperative follow-up of colon cancer. Bronchoscopy showed a polypoid tumor in the orifice of the left upper segmental bronchus. Lipoma was diagnosed by a bronchoscopic biopsy. We performed a segmentectomy of the upper division of the left lung because the tumor was presumed to be located peripherally to the left B3 segmental bronchus. A histopathological examination revealed that the tumor was an endobronchial lipomatous hamartoma that extended to the pulmonary parenchyma beyond the bronchial wall.

[Excision of a Rapidly Enlarged Bronchogenic Cyst Infected after Endoscopic Ultrasound-guided Fine Needle Aspiration].

We report the case of a 75-year-old woman who developed acute mediastinitis from an infected bronchogenic cyst due to endoscopic ultrasound-guided transesophageal fine-needle aspiration (EUS-FNA) for making diagnosis. The patient developed fever, chest pain, and discomfort after EUS-FNA. A repeat chest computed tomography( CT) demonstrated a rapidly increased size of the mediastinal mass. Thoracoscopic surgery was performed five days after EUS-FNA and the mediastinal mass was excised successfully. Postoperative histological examination confirmed the diagnosis of a bronchogenic cyst.

Shrinking rates of polymer gels composed of star-shaped polymers of N-isopropylacrylamide and dimethylacrylamide copolymers: the effect of dimethylacrylamide on the crosslinking network.

Thermoresponsive polymer gels can be applied as culture beds for cell sheets, drug release agents for drug delivery, and sensing materials. In general, the shrinkage behavior of thermoresponsive polymer gels is complex, and they may require much longer times than swelling to reach thermodynamically stable shrinkage states. This slow volume change during shrinkage is often a drawback in using reversible changes in polymer gel volumes with changing temperature for applications such as those described above, and attempts have been made to improve the shrinkage rates of polymer gels. However, using the conventional method results in a low density of the three-dimensional crosslinked network comprising the polymer gel, which weakens the mechanical properties of the polymer gel. In this study, we investigated the effects of monomer arrangement and composition for star-shaped polymers composed of N-isopropylacrylamide and N,N-dimethylacrylamide on the shrinkage behavior of gels comprising star-shaped polymers with the aim of increasing their shrinkage rates without reducing the network densities of the temperature-responsive polymer gels. Based on selective network decomposition by methanolysis and SAXS measurements, the network structures of the obtained spherical gels were found to be more homogeneous than those of polymer gels obtained by conventional free radical polymerization. These gels exhibited reversible volume changes in water, with low-temperature swelling and high-temperature shrinkage. The rates of volume changes from a high temperature shrunken state to a low temperature swollen one were almost the same for all gels. However, the rates of volume changes from low-temperature swollen states to high-temperature shrunken states varied greatly depending on the compositions and sequences of monomers that made up the polymer networks. We confirmed that the introduction of more than 20% DMA as a block copolymer in the network suppressed phase separation and formation of a skin layer and the water inside the polymer gel drained smoothly to the outside, which resulted in an increase in the shrinkage speed.

Heterogeneous dynamics in the curing process of epoxy resins.

Epoxy resin is indispensable for modern industry because of its excellent mechanical properties, chemical resistance, and excellent moldability. To date, various methods have been used to investigate the physical properties of the cured product and the kinetics of the curing process, but its microscopic dynamics have been insufficiently studied. In this study, the microscopic dynamics in the curing process of a catalytic epoxy resin were investigated under different temperature conditions utilizing X-ray photon correlation spectroscopy. Our results revealed that the temperature conditions greatly affected the dynamical heterogeneity and cross-linking density of the cured materials. An overview of the microscopic mechanism of the curing process was clearly presented through comparison with the measurement results of other methods, such as 1H-pulse nuclear magnetic resonance spectroscopy. The quantification of such heterogeneous dynamics is particularly useful for optimizing the curing conditions of various materials to improve their physical properties.

Glassy Porphyrin/C60 Composites: Morphological Engineering of C60 Fullerene with Liquefied Porphyrins.

Morphological control of C60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C60 in toluene afforded the porphyrin/C60 composite with a 3:1 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C60 interactions operate the formation of the porphyrin/C60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C60 interaction in the bulk porphyrin matrices, i.e., "supramolecular solvation". The glassy nature of the porphyrin matrices was transmitted to C60 through the specific interaction, and the porphyrin/C60 composites adopted glassy states at room temperature.

Anisotropic Amorphous X-ray Diffraction Attributed to the Orientation of Cyclodextrin.

The beauty of cyclic molecules is reflected in their host-guest complexation reactions, as well as their unique X-ray diffraction patterns. Cyclodextrins, the longest known host molecules with rigid ring structures, show anisotropic X-ray diffraction characteristic of their single-molecule structure, rather than their intermolecular relationships. Amorphous derivatives of α-cyclodextrin exhibit broad and strong halo diffractions in the solid, melted, and dilute solution states. The diffraction angle corresponds to the intramolecular distance between neighboring glycosidic oxygen atoms located at the vertices of a regular hexagonal array. Because the hexagon is parallel to the aperture plane of the rigid cyclic molecule, the diffraction appears only in the direction parallel to this plane. The anisotropy was confirmed by stretching an amorphous thermoplastic polymer threaded through the inclusion cavities of a sequence of cyclodextrins. The resultant unique anisotropic X-ray diffraction suggests the possible use of rigid cyclic molecules as molecular orientation probes.

Dynamical Heterogeneity near Glass Transition Temperature under Shear Conditions.

We experimentally studied the shear effect on dynamical heterogeneity near glass transition temperature. X-ray photon correlation spectroscopy was utilized to study the dynamics of polyvinyl acetate with tracer particles near its glass transition temperature, to determine the local shear rate from the anisotropic behavior of the time autocorrelation function and to calculate the dynamical heterogeneity using higher-order correlation function. The obtained results show a decrease in the dynamical heterogeneity and faster dynamics with increasing shear rate. This is the first experimental result that proved the predictions of previous molecular dynamics simulations.

Energy dissipation via the internal fracture of the silica particle network in inorganic/organic double network ion gels.

Inorganic/organic double network (DN) ion gels, which are composed of an inorganic silica particle network, an organic poly(N,N-dimethylacrylamide) (PDMAAm) network, and a large amount of ionic liquid, showed excellent mechanical strength of over 25 MPa compression fracture stress at an 80 wt% ionic liquid content. The excellent mechanical strength of these inorganic/organic DN ion gels was attributed to the energy dissipation of the inorganic/organic DN structure. It has been considered that the energy dissipation in inorganic/organic DN ion gels is caused by the internal fracture of the silica particle network, which is preferentially fractured by deformation. However, no studies aiming to investigate the internal fracture of the silica particle network in inorganic/organic DN ion gels have been conducted by direct approaches. In this study, the internal fracture of the silica particle network in the inorganic/organic DN ion gel was directly evaluated by a small angle X-ray scattering (SAXS) technique. The synchrotron SAXS measurements conducted under a uniaxial loading-unloading process demonstrated that the aggregation size of the silica particle network irreversibly decreased with uniaxial stretch. Based on these results, it was clarified that the energy dissipation of the inorganic/organic DN ion gels was attributed to the internal fracture of the silica particle network.

Static structure and dynamical behavior of colloidal liquid crystals consisting of hydroxyapatite-based nanorod hybrids.

Biominerals such as bones and teeth have elaborate nanostructures composed of aligned anisotropic hydroxyapatite (HAp) nanocrystals, which results in excellent mechanical properties. Construction of such ordered structures of HAp nanocrystals in synthetic materials is challenging. Recently, we reported that HAp-nanorod-based colloidal liquid crystals could be obtained. In the present study, the static structure and dynamics of liquid-crystalline (LC) colloidal dispersions of HAp nanorods are investigated by using small-angle X-ray scattering (SAXS) and X-ray photon correlation spectroscopy (XPCS). The SAXS results reveal that the interparticle distance decreases with increasing HAp concentration, φHAp, and the decrease of the interparticle distance for the short-axis direction is significantly smaller in the LC phase than the interparticle distance in the isotropic phase. In the dynamical studies of the LC phase using XPCS, we observe the diffusive motion of the HAp colloids, with the diffusion coefficient being dependent on the wave number. The diffusive motion slows down with increasing φHAp. We observe anisotropic dynamics after long-term storage (160 days after sealing), whereas only isotropic dynamics are observed in the initial XPCS measurements after short-term storage (14 days after sealing). Moreover, we have found that the dynamics slows down with increasing storage time.

[Postoperatively Diagnosed Pulmonary Actinomycosis;Report of Three Cases].

Three cases of pulmonary actinomycosis have been postoperatively diagnosed in our hospital in the past 3 years. All the cases were preoperatively difficult to differentiate from lung cancer, and all were diagnosed in men. One of the patients was diagnosed on the basis of clinical symptoms, while the other 2 patients were diagnosed during the treatment and follow-up of other diseases. On radiological examination, 2 patients showed mass-like shadows, and the 3rd showed a cavitary lesion; fluorodeoxyglucose (FDG) -positron emission tomography showed high FDG accumulation in all the patients. One of the patients was pathologically suspected with lung cancer on transbronchial lung biopsy. Right upper lobectomy was performed in 2 patients, and right lower lobectomy in 1. One of the patients who underwent right upper lobectomy, also received chest wall resection because of the perioperative finding of chest wall invasion of lung cancer. Clinically, all the cases were preoperatively diagnosed as lung cancer.

Dynamical crossover between hyperdiffusion and subdiffusion of polymer-grafted nanoparticles in a polymer matrix.

The dynamical behavior of polystyrene-grafted silica nanoparticles dispersed in an atactic polystyrene matrix was studied using x-ray photon correlation spectroscopy. The time-autocorrelation functions were subjected to fitting analyses based on continuous-time random walk models. The nanoparticles exhibited non-Brownian behavior, and as the temperature increased, the crossover from hyperdiffusion to subdiffusion occurred at 1.25T_{g}, where T_{g} is the glass transition temperature of the matrix polystyrene. Hyperdiffusive behavior is caused by the dynamical heterogeneity of the polymer matrix associated with the glass transition. When the temperature was higher than 1.25T_{g}, the interaction of the grafted polymers with the polymer matrix became relatively significant, and caused a dramatic change in the dynamical behavior of the nanoparticles.

Confinement-Induced Crystal Growth in One-Dimensional Isotactic Polystyrene Nanorod Arrays.

This work demonstrates the anomalous crystal growth of isotactic polystyrene (iPS) in nanorod arrays with different rod sizes. At the bottom of the nanorods, the crystals in bulk film grow into nanorods along either the [110] or [100] direction parallel to the rod axis. On the top side of the nanorods, the polymer exhibits different orientations corresponding to weak or strong confinement. In the weaker confinement (bigger nanorods of 300 nm diameter), the crystals grow with the [100] direction along the nanorod, which is similar to the crystals developed in the radial of spherulite. In the stronger confinement (smaller nanorods of 65 nm diameter), the splaying of crystals in the rod is significantly suppressed, and the preferred growth direction of iPS crystals is kept in either the [110] or [100] direction. The precise control of polymer crystal orientation and crystallinity at a local scale opens important perspectives for the design of one-dimensional nanomaterials whose performance depends on the anisotropic crystal properties.

X-ray photon correlation spectroscopy using a fast pixel array detector with a grid mask resolution enhancer.

The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy (XPCS) measurements to investigate fast dynamics on a microscopic scale. A detecting system, in which each pixel of a single-photon-counting pixel array detector, PILATUS, is covered by grid mask apertures, was constructed for XPCS measurements of silica nanoparticles in polymer melts. The experimental results are confirmed to be consistent by comparison with other independent experiments. By applying this method, XPCS measurements can be carried out by customizing the hole size of the grid mask to suit the experimental conditions, such as beam size, detector size and sample-to-detector distance.