Effect of the Fiber Diameter of Polyamide 11 Nanofibers on Their Internal Molecular Orientation and Properties.

Herein, the effect of the diameter of polyamide 11 nanofibers (PA11 NFs) on their internal structures as well as thermal and mechanical properties is investigated. Aligned PA11 NFs with diameters ranging from 109 to 462 nm are prepared by the single-component solvent electrospinning of different PA11/1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solutions (4-8 wt%) and subsequently characterized. Owing to the similar hydrogen bond formation within the NFs during electrospinning, all prepared NFs have δ'-phase crystals with similar crystallinities and crystallite sizes. However, the orientation of the δ'-phase crystals is disrupted in NFs with diameters less than 200 nm, due to the rapid solidification during electrospinning. The δ'-phase crystals are the most highly oriented within NFs having a fiber diameter of ≈300 nm, and the corresponding NF sheets exhibit the highest mechanical strength. A single PA11 NF with a fiber diameter of ≈300 nm also exhibits a good piezoelectric response (piezoelectric coefficient d33 = 2.1 pm V-1 ).

Persistent Water Repellency of Syndiotactic Polymethylene with Perfluoroethyl Hexyloxycarbonyl Side Chains.

Polyacrylates bearing long fluoroalkyl (Rf) side chains are known to have ultralow surface energies that are appropriate for functional coating and fabric finishing. However, these long Rf chains cause health concerns because of the risk of toxic and bioaccumulative perfluoroalcanoic acid emission via oxidative degradation. This work demonstrates that incorporating a short Rf chain of perfluoroethylene at the end of the side chains of syndiotactic poly(substituted methylene) (PM) produces hydrophobicity. A contact angle of 105° of PM remains constant for more than 50 s, whereas that of the polyacrylate (PA) with the same side chain rapidly decreases from 85° to 44° over the same period. Such persistent water repellency of the PM is ascribed to a liquid crystal structure comprised the main chains arranged in a 2D hexagonal lattice and side chains that extend perpendicularly from these main chains.

Absence of HOMO/LUMO Transition in Charge-Transfer Complexes of Thienoacenes.

In charge-transfer complexes, transition from the donor highest occupied molecular orbital (HOMO) to the acceptor lowest unoccupied molecular orbital (LUMO) gives the charge-transfer absorption. However, in tetracyanoquinodimethane (TCNQ) complexes of thienoacenes, comparison of the observed and calculated charge-transfer absorption demonstrates that the HOMO/LUMO transition is absent in the solid state owing to the orbital symmetry, and the first near-infrared band comes from the transition from the donor next HOMO to the TCNQ LUMO. Maps of the oscillator strength in rotated and translated molecular geometries are calculated on the basis of the time-dependent density functional theory, in which the absence of the HOMO/LUMO transition is approximately maintained even in the general molecular geometry.

Significant Improvement of Unipolar n-Type Transistor Performances by Manipulating the Coplanar Backbone Conformation of Electron-Deficient Polymers via Hydrogen Bonding.

The development of high-performance unipolar n-type semiconducting polymers still remains a significant challenge. Only a few examples exhibit a unipolar electron mobility over 5 cm2 V-1 s-1. In this study, a series of new poly(benzothiadiazole-naphthalenediimide) derivatives with a high unipolar electron mobility (µe) up to 7.16 cm2 V-1 s-1 in thin-film transistors are reported. The dramatically increased µe is achieved by finely optimizing the coplanar backbone conformation through the introduction of vinylene bridges, which can form intramolecular hydrogen bonds with the neighboring fluorine and oxygen atoms. The hydrogen-bonding functionalities are fused to the backbone to ensure a much more planar conformation of the conjugated π-system, as demonstrated by the density functional theory (DFT)-based calculations. The theoretical prediction is in good agreement with the experimental results. As the coplanarity is promoted by the hydrogen bonding, the thin-film crystallinity and molecular packing strength are also improved, which is evidenced by the synchrotron two-dimensional grazing-incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM) measurements. Notably, the GIWAXS measurements reveal an extremely short π-π stacking distance of 3.40 Å. Overall, this study marks a significant advance in the unipolar n-type semiconducting polymers and offers a general approach for further increasing the electron mobility of semiconducting polymers in organic electronics.

Significant Difference in Semiconducting Properties of Isomeric All-Acceptor Polymers Synthesized via Direct Arylation Polycondensation.

The direct arylation polycondensation (DArP) appeared as an efficient method for producing semiconducting polymers but often requires acceptor monomers with orienting or activating groups for the reactive carbon-hydrogen (C-H) bonds, which limits the choice of acceptor units. In this study, we describe a DArP for producing high-molecular-weight all-acceptor polymers composed of the acceptor monomers without any orienting or activating groups via a modified method using Pd/Cu co-catalysts. We thus obtained two isomeric all-acceptor polymers, P1 and P2, which have the same backbone and side-chains but different positions of the nitrogen atoms in the thiazole units. This subtle change significantly influences their optoelectronic, molecular packing, and charge-transport properties. P2 with a greater backbone torsion has favorable edge-on orientations and a high electron mobility µe of 2.55 cm2 V-1 s-1 . Moreover, P2-based transistors show an excellent shelf-storage stability in air even after the storage for 1 month.

Polyelectrolyte Composite Membranes Containing Electrospun Ion-Exchange Nanofibers: Effect of Nanofiber Surface Charges on Ionic Transport.

Poly(vinyl alcohol) (PVA)-based ion-exchange nanofibers (IEX-NFs) and their composite polyelectrolyte membranes were prepared and characterized. The PVA-based NFs are well dispersed and form a three-dimensional network structure in the polymer matrix, Nafion. All of the prepared membranes show a similar ion-exchange capacity of ∼1.0 mmol g-1. The ionic conductivities through the PVA- b-PSS-NF/Nafion composite membranes are superior to that of the Nafion membranes, but the conductivity through the PVA-NF/Nafion composite membrane is half that of the Nafion membrane. Our electrokinetic measurements clearly indicate that a high density of ion-exchange groups on the NF surface results in a continuous ionic transport path in the polymer matrix. In addition, the mechanical strength of all of the NF-composite membranes is improved compared with that of the membranes without NF.

[Surgical Resection of an Intraductal Papillary Mucinous Carcinoma Observed on Imaging Four Years after the Initial Diagnosis].

We herein report a 75-year-old woman who presented with an intraductal papillary mucinous carcinoma(IPMC)who was treated with surgical resection 4 years after the initial diagnosis was made. She previously underwent a high anterior resection of the rectum for rectal cancer at 71 years of age. Preoperative CT revealed a multilocular cystic mass measuring 6 cm in size in the body of the pancreas, which was considered benign. We followed up the intraductal papillary mucinous neoplasm(IPMN) by using annual CT imaging for 4 years. CT revealed a gradual increase in the size of the mass and the development of an intramural nodule in the IPMN. Endoscopic retrograde pancreatography revealed dilatations of the main pancreatic duct communicating with the multilocular cystic lesion. The cytology of the pancreatic juice demonstrated class III b. We therefore diagnosed the patient as having IPMC and performed total pancreatectomy. The postoperative course was uneventful without any recurrence. To our knowledge, only few reports have described the natural history of IPMNs. This resected case of IPMC is rare on the basis of our observation of the natural history of an IPMN using long-term imaging studies.

[Resection of a Granulocyte Colony-Stimulating Factor-Producing Anaplastic Carcinoma of the Pancreas, Associated with Humoral Hypercalcemia of Malignancy].

We herein report the case of a 65-year-old man who presented with an anaplastic carcinoma of the pancreas, producing granulocyte colony-stimulating factor (G-CSF). The patient's laboratory data showed an increase in his serum CA19-9 levels 1 year after he had undergone surgery for transverse colon cancer. Computed tomography (CT) showed a mass in the pancreatic head. Following a diagnosis of primary or metastatic pancreatic cancer, we performed the pancreatoduodenectomy. The postoperative course was uneventful. However, on postoperative day 28, he suffered a disturbance of consciousness and demonstrated hypercalcemia with elevated serum levels of parathyroid hormone-related protein (PTHrP). CT revealed multiple liver metastases and massive ascites. His serum Ca level decreased temporarily, and he subsequently died 58 days after the pancreatoduodenectomy. A pathological examination revealed pleomorphic-type anaplastic carcinoma of the pancreas. Immunohistochemical staining showed the tumor cells to be positive for G-CSF. To the best of our knowledge, there have been no reports of G-CSF-producing anaplastic carcinoma of the pancreas associated with humoral hypercalcemia of malignancy.

Excessive visceral fat area as a risk factor for early postoperative complications of total gastrectomy for gastric cancer: a retrospective cohort study.

BACKGROUND: Obesity is a known risk factor for complications after digestive surgery. Body mass index (BMI) is commonly used as an index of obesity but does not always reflect the degree of obesity. Although some studies have shown that high visceral fat area (VFA) is associated with poor outcomes in digestive surgery, few have examined the relationship between VFA and total gastrectomy. In this study, we demonstrated that VFA is more useful than BMI in predicting complications after total gastrectomy. METHODS: Seventy-five patients who underwent total gastrectomy for gastric cancer were enrolled in this study; they were divided into two groups: a high-VFA group (n = 26, ≥100 cm(2)) and a low-VFA group (n = 49, <100 cm(2)). We retrospectively evaluated the preoperative characteristics and surgical outcomes of all patients and examined postoperative complications within 30 days of surgery (including cardiac complications, pneumonia, ileus, anastomotic leakage, pancreatic fistula, incisional surgical site infection [SSI], abdominal abscess, and hemorrhage). RESULTS: The incidence of anastomotic leakage (p = 0.03) and incisional SSI (p = 0.001) were higher in the high-VFA group than in the low-VFA group. No significant differences were observed in the other factors. We used univariate analysis to identify risk factors for anastomotic leakage and incisional SSI. Age and VFA were risk factors for anastomotic leakage, and BMI and VFA were risk factors for incisional SSI. A multivariate analysis including these factors found that only VFA was a predictor of anastomotic leakage (hazard ratio [HR] 4.62; 95 % confidence interval [CI] 1.02-21.02; p = 0.048) and incisional SSI (HR 4.32; 95 % CI 1.18-15.80; p = 0.027]. CONCLUSIONS: High VFA is more useful than BMI in predicting anastomotic leakage and SSI after total gastrectomy. Therefore, we should consider the VFA value during surgery.

Differentiation of chemical reaction activity of various carbon nanotubes using redox potential: Classification by physical and chemical structures.

The present study systematically examined the kinetics of a hydroxyl radical scavenging reaction of various carbon nanotubes (CNTs) including double-walled and multi-walled carbon nanotubes (DWCNTs and MWCNTs), and carbon nano peapods (AuCl3@DWCNT). The theoretical model that we recently proposed based on the redox potential of CNTs was used to analyze the experimental results. The reaction kinetics for DWCNTs and thin MWCNTs agreed well with the theoretical model and was consistent with each other. On the other hand, thin and thick MWCNTs behaved differently, which was consistent with the theory. Additionally, surface morphology of CNTs substantially influenced the reaction kinetics, while the doped particles in the center hollow parts of CNTs (AuCl3@DWCNT) shifted the redox potential in a different direction. These findings make it possible to predict the chemical and biological reactivity of CNTs based on the structural and chemical nature and their influence on the redox potential.

Radical scavenging reaction kinetics with multiwalled carbon nanotubes.

Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer CNTs. To pursue safety by design, the redox potential in reactions with CNTs has been contemplated recently. However, the chemical reactivity of CNTs has not been explored kinetically, so that there is no scheme to express a redox reaction with CNTs, though it has been investigated and reported. In addition, the reactivity of CNTs is discussed with regard to impurities that consist of transition metals in CNTs, which obfuscates the contribution of CNTs to the reaction. The present work aimed at modeling CNT scavenging in aqueous solution using a kinetic approach and a simple first-order reaction scheme. The results show that CNTs follow the redox reaction assumption in a simple chemical system. As a result, the reaction with multiwalled CNTs is semi-quantitatively denoted as redox potential, which suggests that their biological reactions may also be evaluated using a redox potential scheme.

[Complete Response in Far-Advanced Esophageal Cancer Treated with Induction Chemotherapy Followed by Definitive Chemoradiotherapy].

We report a case of far-advanced esophageal cancer in which induction chemotherapy followed by chemoradiotherapy achieved complete remission. A 61-year-old female presented to our hospital with dyspnea and hoarseness. CT revealed a tumor at the cervical esophagus invading and narrowing the trachea, a bulky metastasis at the right paraesophageal node, and nodal metastases at levels II and III of the left neck. No finding indicated other distant metastases. According to findings of CT and endoscopy, she was diagnosed with unresectable cancer at the cervical esophagus(cT4bN1M1[LYM], according to UICC-TNM 7 th). After 2 courses of induction chemotherapy(DTX, CDDP, and 5-FU), the tumor's volume was remarkably reduced. Thereafter, chemoradiotherapy with CDDP, 5-FU, and 60 Gy/30 Fr was administered. After 7 months of systemic chemotherapy with paclitaxel following chemoradiotherapy, the patient was judged to have complete remission based on CT and endoscopic findings. After additional administration of S-1 for 5 months, systemic chemotherapy was ceased. The patient has survived without disease progression for 22 months following initiation of treatment. It is thought that induction chemotherapy followed by chemoradiotherapy might improve local control and survival of patients with far-advanced esophageal cancers, such as our patient.

Structure-Piezoelectric Property Relationships of Thin Films Composed of Electrospun Aligned Poly(vinylidene fluoride) Nanofibers.

In the past two decades, many studies on piezoelectric nanofibers (NFs) prepared from poly(vinylidene fluoride) (PVDF) and its copolymers, including single NFs, randomly oriented nonwoven mats, and aligned NFs, have been reported. However, studies on the relationships between the PVDF NF diameter, the orientation of the ß-phase crystals inside NFs, and the piezoelectric properties of the NFs are still limited. In this study, the effect of the fiber diameter on the internal molecular packing/orientation and piezoelectric properties of aligned PVDF NF thin films was investigated. Herein, piezoelectric thin films composed of densely packed, uniaxially aligned, PVDF NFs with diameters ranging from 228 to 1315 nm were prepared by means of electrospinning with a rotating collector and successive hot-pressing and poling. The effect of the diameters of PVDF NFs on their internal structures, as well as the piezoelectric properties of the thin films, was investigated. All prepared NFs mainly contained ß-phase crystals with a similar total crystallinity. The orientation of the ß-phase crystals inside the NFs increased with an increase in the fiber diameter, resulting in an improved transverse piezoelectric coefficient (d31) for the thin films. The output voltage of the prepared thin films reached a maximum of 2.7 V at 104 Hz.

All-Perfluorosulfonated-Ionomer Composite Membranes Containing Blow-Spun Fibers: Effect of a Thin Fiber Framework on Proton Conductivity and Mechanical Properties.

In this study, thin fiber composite polymer electrolyte membranes (PEMs) were prepared using short side-chain perfluorosulfonic acid (PFSA) ionomers, Aquivion, to create composite PEMs with improved proton conductivity and improved mechanical properties. PFSA thin fiber webs prepared by blow spinning and successive hot pressing were used as the porous substrate. Herein, PFSA ionomers were used for both the substrate and the matrix of the composite PEMs, and their structures, properties, and fuel cell performance were characterized. By adding the PFSA thin fiber webs to the matrix, the proton conductivity was enhanced and the mechanical properties were slightly improved. The prepared PFSA thin fiber composite PEM showed better FC performance than that of the pristine PFSA one for the high-temperature low-humidity condition in addition to the low-temperature high-humidity one. To the best of our knowledge, this is the first report on the all PFSA composite membranes containing a PFSA thin fiber framework.

Universal Murray's law for optimised fluid transport in synthetic structures.

Materials following Murray's law are of significant interest due to their unique porous structure and optimal mass transfer ability. However, it is challenging to construct such biomimetic hierarchical channels with perfectly cylindrical pores in synthetic systems following the existing theory. Achieving superior mass transport capacity revealed by Murray's law in nanostructured materials has thus far remained out of reach. We propose a Universal Murray's law applicable to a wide range of hierarchical structures, shapes and generalised transfer processes. We experimentally demonstrate optimal flow of various fluids in hierarchically planar and tubular graphene aerogel structures to validate the proposed law. By adjusting the macroscopic pores in such aerogel-based gas sensors, we also show a significantly improved sensor response dynamics. In this work, we provide a solid framework for designing synthetic Murray materials with arbitrarily shaped channels for superior mass transfer capabilities, with future implications in catalysis, sensing and energy applications.

A highly conducting organic metal derived from an organic-transistor material: benzothienobenzothiophene.

BTBT ([1]benzothieno[3,2-b][1]benzothiophene) is an organic semiconductor that realizes high mobility in organic transistors. Here we report that the charge-transfer (CT) salt, (BTBT)2PF6, shows a high room-temperature conductivity of 1500 S cm(-1). This compound exhibits a resistivity jump around 150 K, but when it is covered with Apiezon N grease the resistivity jump is suppressed, and the metallic conductivity is maintained down to 60 K. Owing to the very high conductivity, the ESR signal shows a significantly asymmetric Dysonian lineshape (A/B ≅ 3) even at room temperature. Since most organic conductors are based on strong electron donors, it is remarkable that such a weak electron donor as BTBT realizes a stable and highly conducting organic metal.

[A patient with advanced gastroesophageal junction cancer responding completely to S-1 monotherapy].

A 74-year-old woman was referred to our hospital for a close examination. A gastrointestinal endoscopic examination revealed an advanced gastroesophageal junction cancer type 3, which was diagnosed as well-differentiated adenocarcinoma. Computed tomography(CT)showed liver and para-aortic lymph node metastases.She was treated with oral S-1 at 100mg/ day for 28 days, followed by a 14-day rest. After 3 courses of treatment, the primary tumor was greatly reduced. After 18 months of treatment, CT showed a complete response of the liver and also the para-aortic lymph node metastases. She is alive without severe adverse effects and recurrence 2.5 years after the start of S-1 administration.

A case study of pyloric stenosis caused by metastatic lobular carcinoma of breast.

Metastasis to the gastrointestinal tract is rare. A 59-year-old woman who had a history of an invasive lobular carcinoma of breast with clinical complete response visited our hospital and complained of an upper abdominal pain and distension. We performed an upper gastrointestinal endoscopy which showed only a gastric ulcer without any malignant findings. She experienced a recurrence of symptoms 2 months after this visit. An endoscopy revealed pyloric stenosis, which did not improve with balloon dilatation. We performed a gastro-jejunal and cecal-transverse colonic bypass surgery. Diffuse wall thickening of the antrum was verified during the surgery, and a biopsy sample was collected. The diagnosis of gastric metastasis from breast was confirmed since it showed the same immunohistochemistry pattern as the prior breast lesion. Pyloric stenosis has still been confirmed with an endoscopy, she has been alive with satisfactory oral food intake for >10 years.

Current-Voltage Characteristics and Solvent Dissociation of Bipolar Membranes in Organic Solvents.

In this work, the chronopotentiometric responses, pH changes, and current-voltage (I-V) characteristics of bipolar membrane (BPM)/LiCl-organic solvent systems were measured and compared with those of the BPM/LiCl-water system. Monohydric alcohols, polyhydric alcohols, and amides were used as organic solvents. The chronopotentiograms and pH changes supported that the organic solvents can dissociate into cations and anions at the BPM interface. It is found that amides cannot dissociate easily at the BPM compared with alcohols. The I-V characteristics showed that both the viscosity and acid-base property of organic solvents substantially influences the dissociation behaviors in addition to the autoprotolysis constant and relative permittivity of the solvents.