Successful treatment with laparoscopy-assisted surgery for ileal perforation due to an ingested foreign body: A report of two cases.

INTRODUCTION: Presently, the advantage of laparoscopic surgery is widely recognized and it is gaining popularity not only in elective abdominal surgeries but also in various kinds of emergent abdominal surgeries. This report describes two patients diagnosed with ileal perforation due to an ingested foreign body (FB)-a rare abdominal emergency-who were treated laparoscopically. PRESENTATION OF CASE: Both patients were brought in by an ambulance to our hospital, with complaints of increasing lower abdominal pain. Computed tomography scan revealed a small bowel perforation due to an ingested FB in both patients, and laparoscopy-assisted partial ileal resection was immediately performed. Their postoperative recoveries were uneventful. DISCUSSION: Both patients with this rare abdominal emergency were successfully treated with laparoscopic surgery. Its feasible diagnostic and therapeutic abilities and decreased invasiveness contributed to their uneventful and fast recoveries. Extracorporeal handling of the affected small bowel via mini-laparotomy was useful in this setting as it was safe, fast, and cost-effective. CONCLUSION: Laparoscopic surgery is effective, even for this rare abdominal emergency. Moreover, laparoscopy-assisted surgery accompanying mini-laparotomy is a rational treatment approach, especially for this condition.

Quantum Master Equation Approach to Singlet Fission Dynamics in Pentacene Linear Aggregate Models: Size Dependences of Excitonic Coupling Effects.

The singlet fission (SF) dynamics of pentacene linear aggregate models are investigated using the quantum master equation method by focusing on the Frenkel excitonic (FE) coupling effects on the SF rate and double triplet (TT) yield as well as on their aggregate size dependences. It is found that for the dimer model, unrealistically large FE couplings are needed to provide significant effects on the SF dynamics, while for the larger aggregate models a realistic FE coupling causes significant variations in the SF dynamics: as increasing the aggregate size, the SF rate rapidly increases, attains the maximum at 8-mer (~3 times enhancement as compared to the non-FE-coupling case) and then decreases, approaching a stationary value after 12-mer, although the stationary TT yield at 20-mer remains slightly smaller than that in the non-FE-coupling case. These features are explained based on the relative relaxation factors between the adiabatic exciton states. The present results contribute to constructing the design guidelines for highly efficient SF aggregates. © 2018 Wiley Periodicals, Inc.

Exploring the novel donor-nanotube archetype as an efficient third-order nonlinear optical material: asymmetric open-shell carbon nanotubes.

Contrary to the enormous number of previous studies on carbon nanotubes (CNTs), herein, we realized the origin of the intrinsic open-shell diradical character and second hyperpolarizability γ using a broken symmetry approach. This study was inspired by our recent findings (S. Muhammad, et al., Nanoscale, 2016, 8, 17998 and Nakano, et al., J. Phys. Chem. C, 2016, 120, 1193). We performed structural modifications through a unique asymmetric donor-nanotube framework, which led to a novel paradigm of modified CNTs with tunable open-shell diradical character and remarkably superior NLO response properties. Interestingly, asymmetry and diradical character were found to be the crucial factors to modulate the second hyperpolarizability γ. We initially performed a comparative analysis of the diradical characters and γ amplitudes of boron nitride nanotubes (BNNTs) and CNTs possessing significant ionic characters and covalent characters, respectively. The basic findings for these simple configurations were further extended to the donor-acceptor CNT paradigm, which finally led to excellent asymmetric donor-CNT configurations with remarkably larger γ amplitudes. Furthermore, among the CNTs, finite length zigzag CNT(6,0)3 were modified with different donor-acceptor configurations. Interestingly, for the first time, unique donor-nanotube configurations [1,4-(NH2)2CNT-(6,0)3 and 1,4-(NH2)2CNT-(6,0)5] were found; they showed significantly robust γ amplitudes as large as 2519 × 103 and 4090 × 103 a.u. at the LC-UBLYP(µ = 0.33)/6-31G* level of theory. Additionally, several molecular level insights have been obtained for these novel donor-nanotube configurations using their odd electron densities, molecular electrostatic maps, densities of states and γ density analyses to highlight the realization of these novel materials for highly efficient optical and NLO applications.

A gastrointestinal stromal tumor of the jejunum presenting with an intratumoral abscess: A case report and a literature review.

INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. The small intestine is the second-most frequent location where GISTs occur after the stomach. Attention should be paid to small intestinal GISTs because they infrequently present with acute abdomen, which necessitates emergency surgery. This report describes a patient with a small intestinal GIST developing a giant intratumoral abscess, in whom emergency surgery was performed. PRESENTATION OF CASE: A 56-year-old woman presented with worsening abdominal pain. Computed tomography scan showed an approximately 9.5 cm × 9 cm tumor bearing a thick and hypervascularized wall with an internal air-fluid level. Emergency laparotomy revealed the tumor originated from the jejunum, and partial resection of the jejunum was performed. A large amount of pus was contained inside the tumor. Immunohistochemically, the tumor was diagnosed as a high risk GIST of the Cjejunum, and imatinib mesylate was initiated. DISCUSSION AND CONCLUSION: When an intratumoral abscess in the abdomen is confirmed, GISTs should be listed as differential diagnosis. Complete surgical resetcion with careful handling and adjuvant chemotherapy with imatinib mesylate are considered to be important for this state.

Open-Shell Character Dependences of the Second Hyperpolarizability in Two-Dimensional Tetraradicaloids.

The open-shell character dependences of the second hyperpolarizability, γ, are investigated for rectangular-shaped tetraradicaloid models, such as diradical dimers, using numerically exact solutions of the extended Hubbard model. The newly defined local diradical characters for intra- and intermolecular interactions (referred to as yintra and yinter, respectively) are compared to conventional global ones ( y0 and y1) and provide a comprehensive understanding of the electronic structure of the system. The system shows two kinds of enhancements of the γ components, γintra and γinter (caused, respectively, by intra- and intermolecular diradical interactions): (i) a system with a large yintra ( yinter) (>∼0.4) exhibits the enhancement of a single component of γ, γinter (γintra), at the intermediate yinter ( yintra) region (∼0.3-0.4), and (ii) in contrast to conventional diradical systems, the system exhibits a further enhancement of both components of γ (γintra and γinter) at the region where yintra ∼ yinter with small values (≤∼0.3). The obtained relationships are verified by using ab initio quantum chemical calculations of the realistic tertraradical models of a 4,4'-bis(1,2,3,5-dithiazdiazolyl) (BDTDA) dimer and a disilene dimer. The present results are expected to pioneer an alternative class of two-dimensional multiradical NLO systems, which potentially cause further enhancement of γ as compared with conventional intermediate diradical NLO systems.

Antegrade jejunogastric intussusception and common bile duct stones at 14 months after gastrectomy and cholecystectomy: A case report.

INTRODUCTION: Intussusception after gastrectomy is a minor complication after gastrectomy, while common bile duct stone (CBD) is also a rare complication post cholecystectomy. We report a case that simultaneously caused both intussusception and CBD stone following gastrectomy with prophylactic cholecystectomy. CASE PRESENTATION: A 74-year-old woman underwent distal gastrectomy with Roux-en-Y reconstruction and prophylactic cholecystectomy for gastric cancer. After 14 months, the patient reported nausea and vomiting. Abdominal computed tomography scanning showed antegrade intussusception of the Roux limb of the gastrojejunostomy and calculi in the common bile duct, with a diagnosis of jejunogastric intussusception and common bile duct stones. The patient was hospitalized and endoscopic examination was performed on day 3. Endoscopic treatment did not resolve the intussusception, which also obstructed the bile duct stones. Elective surgery was performed on day 10, in which the invaginated Roux limb of the gastrojejunostomy was resected after manual reinstatement to its original position. This was followed by open exploration of the common bile duct and T-tube drainage. The patient was discharged 25days post- surgery. DISCUSSION: Jejunogastric intussusception and CBD stone may require operative management, although the operation could be elective after sufficient examination and preparation. CONCLUSION: Jejunogastric intussusception and bile duct stones are rare after distal gastrectomy, physicians should be alerted to the possibility of these complications.

Diradical and Ionic Characters of Open-Shell Singlet Molecular Systems.

The diradical and ionic natures of open-shell singlet systems have been investigated using new definitions of the diradical and ionic characters as well as of their densities within the valence configuration interaction (VCI) model with two electrons in two active orbitals. The two-site symmetric and asymmetric diradical models are examined by using these diradical/ionic characters. For realistic compounds, we investigate a diradicaloid diphenalenyl and a rectangular graphene nanoflake in the presence of an external static electric field, as well as π-stacked phenalenyl-derivative dimers with varying the intermonomer distance, where the central carbon atoms in the phenalenyl rings are substituted by boron (B) and nitrogen (N) atoms, respectively. It is found that the increase of charge asymmetricity induced by the static electric field decreases the diradical character and finally induces an ionic character in the ground state, while the first excited state is changed from pure ionic to diradical-dominant as the field amplitude increases. On the other hand, when increasing the intermonomer distance, the B/N substitution in the phenalenyl dimer changes the electronic state from open-shell singlet with small diradical character to closed-shell with large ionic character. These results indicate that the application of a static electric field to diradicaloids and the asymmetric substitution of a pancake bonded π-dimer combined with the variation of intermonomer distance could tune the diradical/ionic characters and therefore control the nonlinear optical responses.

Intermolecular Packing Effects on Singlet Fission in Oligorylene Dimers.

Using the density functional theory method, the crystalline packing effect on the singlet fission (SF) rate of oligorylenes, some of which are found to exhibit SF in crystal forms, is revealed by evaluating the effective electronic coupling (|Veff|), the square of which is proportional to the SF rate. The |Veff| values for terrylene and quaterrylene dimer models are investigated for a variety of slip-stacked forms. It is found that these values show similar dependences on the intermolecular packing as a function of lateral and longitudinal displacements of monomer frameworks, and that they are maximized in several configurations of one monomer slipped from another along the longitudinal axis. The present estimation method of the SF rate is also found to qualitatively explain the experimental SF rate difference between terrylene derivatives with different packing forms. Furthermore, by analyzing the effect of electronic couplings on the adiabatic electronic states related to SF, we predict several favorable molecular packings leading to a fast SF with a high triplet yield.

Impact of routine recurrent laryngeal nerve monitoring in prone esophagectomy with mediastinal lymph node dissection.

BACKGROUND: The problem of recurrent laryngeal nerve (RLN) paralysis (RLNP) after radical esophagectomy remains unresolved. Several studies have confirmed that intraoperative nerve monitoring (IONM) of the RLN during thyroid surgery substantially decreases the incidence of RLN damage. This study tried to determine the feasibility and effectiveness of IONM of the RLN during thoracoscopic esophagectomy in the prone position for esophageal cancer. METHODS: All 108 patients who underwent prone esophagectomy at Tohoku University Hospital between July 2012 and March 2015 were included in this study. We divided patients into two groups: a control group (No-Monitoring group, surgery without IONM; n = 54) and a study group (Monitoring group, surgery with IONM; n = 54). In Monitoring group, neural stimulation was performed for both RLNs before and after dissection in the thoracic procedure, then for RLNs and vagus nerves (VNs) in the cervical procedure. The feasibility of IONM in Monitoring group and early surgical outcomes were retrospectively compared with those in No-Monitoring group. RESULTS: IONM could be performed for 47 cases (87.0%) in Monitoring group. Reasons for discontinuation were use of muscle relaxants (3 patients), change in thoracotomy procedure (2 patients), past rib bone fracture (1 patient), and allergic shock by transfusion (1 patient). Right RLNPs were identified postoperatively in 4 patients, and left RLNPs in 23 patients. IONM sensitivities were 92.7 and 88.0% for the right and left VNs, respectively. Incidences of postoperative RLNP, aspiration, and primary pneumonia did not differ significantly between groups. CONCLUSIONS: This study confirmed the feasibility and safety of IONM of the RLN for thoracoscopic esophagectomy in the prone position. No significant differences in postoperative outcomes were seen between esophagectomy with and without IONM.

Theoretical Study on the Second Hyperpolarizailities of Oligomeric Systems Composed of Carbon and Silicon π-Structures.

To explore the prospect of molecules involving silicon-silicon multiple bonds as nonlinear optical molecular systems, the relationship between the structure and the second hyperpolarizabilities γ of the oligomeric systems composed of carbon and silicon π-structures is investigated using the density functional theory method. It is found that these compounds indicate intramolecular charge transfer (ICT) from the silicon units to the carbon units together with nonzero diradical characters. The γ values of these compounds are shown to be 2-13 times as large as those of the carbon analogs. Although asymmetric carbon and silicon π-systems exhibit comparable enhancement to the corresponding symmetric systems, donor-π-donor structures exhibit remarkable enhancement of γ despite of their both-end short silicon π-chain moieties (donor units). Further analysis using the odd electron and γ densities clarifies that the intermediate diradical character also contributes to the enhancement of γ. These results predict that even short π-conjugated silicone moieties can cause remarkable enhancement of γ by introducing them into π-conjugated hydrocarbon structures.

Role of a singlet diradical character in carbon nanomaterials: a novel hot spot for efficient nonlinear optical materials.

Carbon atoms have the potential to produce a variety of fascinating all-carbon structures with amazing electronic and mechanical properties. Over the last few decades, several efforts have been made using experimental and computational techniques to functionalize graphene, carbon nanotubes and fullerenes for potential use in modern hi-tech electronic, medicinal, optical and nonlinear optical (NLO) applications. Since photons replaced electrons as a carrier of information, the field of NLO material design has drawn immense interest in contemporary materials science. There have been several reports of bridging the gap between the exciting fields of carbon nanomaterials and NLO materials by functionalizing carbon nanomaterials for potential NLO applications. In contrast to previous reports of the design of third-order NLO materials using conventional closed-shell materials, a novel strategy using open-shell diradical molecular systems has recently been proposed. Quantum chemically, diradical character is explained in terms of the instability of the chemical bonds in open-shell molecular systems. Interestingly, several carbon nanomaterials, which naturally possess open-shell singlet configurations, have recently gained momentum in the design of these classes of open-shell NLO materials with excellent NLO properties, stability and diversity. The present review establishes a systematic sequence of different studies (spanning over two decades of intense research efforts), starting from the simplest theoretical two-site diradical model, continuing to its experimental and theoretical realization in actual chemical systems, and finally applying the abovementioned model/rule to novel carbon nanomaterials to tune their NLO properties, particularly their second hyperpolarizability (γ). In the present report, we highlight several recent efforts to functionalize carbon nanomaterials by exploiting their open-shell diradical character to achieve efficient third-order NLO properties. Several issues and opportunities are discussed, including the inherited disadvantages of both experimental (the high reactivity and short life of diradical compounds) and quantum (need for multi-reference methodology) techniques when dealing with carbon nanomaterials. A comparative analysis of several quantum chemical investigations, along with contemporary experimental results, will be performed to emphasize the core issues and opportunities related to carbon nanomaterials with singlet open-shell diradical character. Thus, the present review will highlight carbon nanomaterials with diradical/biradical character for their prospective applications in the NLO field.

Diradical Character-Based Design for Singlet Fission of Bisanthene Derivatives: Aromatic-Ring Attachment and π-Plane Twisting.

We demonstrate a diradical character-based molecular design for singlet fission using polycyclic aromatic hydrocarbons, bisanthene derivatives. Two types of chemical modifications-aromatic-ring attachment and π-plane twisting-are examined in order to satisfy the energy level matching condition for singlet fission. Detailed analysis of the electronic structures of the model molecules using nucleus-independent chemical shift, molecular orbitals, and their energies has demonstrated the usefulness of the relationship between the resonance structure and aromaticity and that between nonplanarity of π-conjugated systems and reduction of orbital overlap for tuning the diradical character. This result provides a novel design guideline for polycyclic aromatic hydrocarbons toward efficient singlet fission.

Design Principles of Electronic Couplings for Intramolecular Singlet Fission in Covalently-Linked Systems.

We theoretically investigate the singlet fission in three types of covalently-linked systems, that is, ortho-, meta- and para-linked pentacene dimers, where these are shown to have significantly different singlet fission rates. Each molecule is composed of two chromophores (pentacenes), which are active sites for singlet fission, and covalent bridges linking them. We clarify the origin of the difference in the electronic couplings in these systems, which are found to well support a recent experimental observation. It is also found that the next-nearest-neighbor interaction is indispensable for intramolecular singlet fission in these systems. On the basis of these results, we present design principles for efficient intramolecular singlet fission in covalently-linked systems and demonstrate the performance by using several novel conjugated linkers.

Biphenalenylidene: Isolation and Characterization of the Reactive Intermediate on the Decomposition Pathway of Phenalenyl Radical.

First isolation and characterization of biphenalenylidenes, which have long been unidentified reactive intermediates on the decomposition pathway of phenalenyl radical, were accomplished. Photoinduced electrocyclic ring-opening reaction of anti-dihydroperopyrene resulted in a successful conversion to E-biphenalenylidene, which enabled a detailed investigation of the electronic structure of E-biphenalenylidene by means of spectroscopic techniques. A stereoisomer, Z-biphenalenylidene, was also observed by suppressing a facile E-Z isomerization to E-biphenalenylidene in a rigid matrix. Furthermore, Z-biphenalenylidene demonstrated a thermal ring-closure in conrotatory process, which is not conforming to the Woodward-Hoffmann rule. These unusual reactivities of biphenalenylidene are ascribed to the ground states destabilized by its singlet biradical character, which was fully supported by theoretical calculations. The presence of E-biphenalenylidene on the decomposition pathway of phenalenyl was confirmed experimentally, leading to the full understanding of the decomposition mechanism of phenalenyl.

Open-Shell Singlet Nature and σ-/π-Conjugation Effects on the Third-Order Nonlinear Optical Properties of Si Chains: Polysilane and Poly(disilene-1,2-diyl).

We theoretically investigate the open-shell singlet nature and σ-/π-conjugation effects on the longitudinal second hyperpolarizabilities (γ) of one-dimensional chains involving silicon-silicon bonds, that is, polysilane and poly(disilene-1,2-diyl), by comparison with their carbon analogues, polyethylene and polyacetylene, respectively. It is found that poly(disilene-1,2-diyl) has less bond length alternation than polyacetylene and that σ-conjugation of polysilane is less effective on the enhancement of γ than π-conjugation of polyacetylene, whereas π-conjugation of poly(disilene-1,2-diyl) indicates a more than 20 times greater enhancement of the γ than that of polyacetylene, which is known to be a typical nonlinear optical molecule with large γ, for one-dimensional chains involving 3-5 double bonds. Further theoretical analyses of poly(disilene-1,2-diyl) reveal the σ- and π-electrons contribute negatively and positively to the γ, respectively. The latter contribution is significantly larger than the former and thus causes the remarkable enhancement of γ amplitudes due to the emerging open-shell singlet nature in the long π-conjugation length.

Challenging compounds for calculating molecular second hyperpolarizabilities: the triplet state of the trimethylenemethane diradical and two derivatives.

The second hyperpolarizability γ of trimethylenemethane (TMM) and two 1,3-dipole derivatives (NXA and OXA) in their triplet ground state has been evaluated at the UCCSD(T) level with the d-aug-cc-pVDZ extended basis set, highlighting that γ decreases from TMM to NXA and OXA, following the opposite order of their permanent dipole moments. These results are then used to benchmark a broad range of levels of approximation. So, the UMP2, UMP4, and UCCSD methods can be used to characterize γ of TMM and NXA but not of OXA. In that case, the large field-induced charge transfer contribution is difficult to handle using the MPn methods and only the UCCSD method provides values close to the UCCSD(T) reference. Turning to the performance of DFT with typical exchange-correlation functionals, the UM06-2X functional, which contains 54% of HF exchange, performs very well with a maximum of 4.5% of difference with respect to the reference values. On the other hand, employing less HF exchange leads to an overestimation of the responses whereas range-separated hybrids generally underestimate the second hyperpolarizabilities. Finally, the use of spin-projected methods for these 1,3-dipole triplet molecules has a little impact since the spin contamination is almost negligible.

Density Analysis of Intra- and Intermolecular Vibronic Couplings toward Bath Engineering for Singlet Fission.

Vibronic coupling plays a crucial role in singlet fission whereby a singlet exciton splits into two triplet excitons. In order to reveal the physicochemical origin of the vibronic coupling associated with singlet fission as well as to clarify its relationship with chemical structure, we evaluate relevant vibronic couplings from the viewpoint of their spatial contributions described by vibronic coupling density. From the analysis using a model tetracene dimer, a typical singlet fission system, the frequency dependence of vibronic couplings in each electronic state is found to be significantly different from that of another depending on the nature of the electronic structure (intra/intermolecular excitation) and the related vibrational motion. These findings contribute not only to the fundamental understanding of the singlet fission mechanism from the viewpoint of vibronic couplings but also to opening a new path to designing highly efficient singlet fission materials through phonon-bath engineering.

Diradical character and nonlinear optical properties of buckyferrocenes: focusing on the use of suitably modified fullerene fragments.

The buckyferrocenes, synthesized through face-to-face fusion of ferrocene and fullerene fragments (C60Me10), are expected to enjoy the rich scientific heritage of ferrocene and fullerene with an extensively large π-conjugation network between the two Fe atoms [Y. Matsuo, K. Tahara and E. Nakamura, J. Am. Chem. Soc., 2006, 128, 7154]. However, the addition of pentamethyl groups at each end of the fullerene fragment breaks the π-conjugation path as well as metal-metal spin correlation between the two-ferrocene faces in a buckyferrocene. We found that the unblocking of π-conjugation from different positions in fullerene fragments have substantial effects on their topologies, spin densities, diradical characters as well as nonlinear optical (NLO) properties of these buckyferrocenes. We study the topological dependence of open-shell diradical character and second hyperpolarizability (γ), the third-order NLO properties at the molecular scale, in several buckyferrocenes. On the basis of their different diradical characters (yi), which are defined by the occupation number of the lowest unoccupied natural orbital (LUNO) + i (i = 0, 1,…), these buckyferrocenes are categorized into three groups, i.e., closed-shell (yi = 0), intermediate open-shell singlet (0 < yi < 1), and almost pure open-shell singlet (yi = 1) compounds. For example, we found that buckyferrocenes including (CpFe)2η(5)C60Me10 and (CpFe)2η(5)C70Me10 have closed-shell configurations. The buckyferrocenes (CpFe)2η(5)C60, (CpFe)2η(5)C70, (CpFe)2η(5)C70Me8, (CpFe)2η(5)C70Me4 and (CpFe)2η(5)C30 are intermediate open-shell singlet, while (CpFe)2η(5)C60Me4 and (CpFe)2η(5)C60Me8 are pure open-shell singlet complexes. Interestingly, the γzzzz amplitude of (CpFe)2η(5)C60, an open-shell intermediate diradical complex, is about 41 times and 13 times as large as those of its closed-shell ((CpFe)2η(5)C60Me10) and pure diradical ((CpFe)2η(5)C60Me8) counterparts, respectively. Similarly, the γzzzz amplitudes of (CpFe)2η(5)C70, (CpFe)2η(5)C70Me4, and (CpFe)2η(5)C70Me8 with intermediate diradical character are about 36, 17, and 9 times as large as that of their closed-shell (CpFe)2η(5)C70Me10 counterpart. The fact that larger γzzzz values are obtained for buckyferrocenes with intermediate diradical characters is in line with the "y-γ correlation" obtained from the valence configuration interaction (VCI) results for a two-site diradical model [M. Nakano, et al., Phys. Rev. Lett., 2007, 99, 033001] as well as for fullerene and graphene systems. The γzzzz density analysis shows that the large positive contributions originate from the large γzzzz density distributions on the upper- and lower-extended edges of the buckyferrocenes, between which significant spin polarizations appear within the spin-unrestricted DFT level of theory. These results demonstrate that such buckyferrocenes are potential candidates for a novel class of open-shell singlet NLO systems, where γzzzz values are modulated by tuning their diradical character through the use of suitably modified fullerene fragments.