Probing equilibrium of molecular and deprotonated water on TiO(110).

Understanding adsorbed water and its dissociation to surface hydroxyls on oxide surfaces is key to unraveling many physical and chemical processes, yet the barrier for its deprotonation has never been measured. In this study, we present direct evidence for water dissociation equilibrium on rutile-TiO(110) by combining supersonic molecular beam, scanning tunneling microscopy (STM), and ab initio molecular dynamics. We measure the deprotonation/protonation barriers of 0.

Anticorrelation between surface and subsurface point defects and the impact on the redox chemistry of TiO2(110).

By using a combination of scanning tunneling microscopy (STM), density functional theory (DFT), and secondary-ion mass spectroscopy (SIMS), we explored the interplay and relative impact of surface versus subsurface defects on the surface chemistry of rutile TiO2 . STM results show that surface O vacancies (VO ) are virtually absent in the vicinity of positively charged subsurface point defects. This observation is consistent with DFT calculations of the impact of subsurface defect proximity on VO formation energy.

First-principles study of phenol hydrogenation on Pt and Ni catalysts in aqueous phase.

The effect of an aqueous phase on phenol hydrogenation over Pt and Ni catalysts was investigated using density functional theory-based ab initio molecular dynamics calculations. The adsorption of phenol and the addition of the first and second hydrogen adatoms to three, ring carbon positions (ortho, meta, and para with respect to the phenolic OH group) were explored in both vacuum and liquid water. The major change in the electronic structure of both Pt(111) and Ni(111) surfaces, between a gaseous and liquid phase environment, results from a repulsion between the electrons of the liquid water and the diffuse tail of electron density emanating from the metal surface.

Site-specific imaging of elemental steps in dehydration of diols on TiO(2)(110).

Scanning tunneling microscopy is employed to follow elemental steps in conversion of ethylene glycol and 1,3-propylene glycol on partially reduced TiO2(110) as a function of temperature. Mechanistic details about the observed processes are corroborated by density functional theory calculations. The use of these two diol reactants allows us to compare and contrast the chemistries of two functionally similar molecules with different steric constraints, thereby allowing us to understand how molecular geometry may influence the observed chemical reactivity.

The role of reducible oxide-metal cluster charge transfer in catalytic processes: new insights on the catalytic mechanism of CO oxidation on Au/TiO2 from ab initio molecular dynamics.

To probe metal particle/reducible oxide interactions density functional theory based ab initio molecular dynamics studies were performed on a prototypical metal cluster (Au20) supported on reducible oxides (rutile TiO2(110)) to implicitly account for finite temperature effects and the role of excess surface charge in the metal oxide. It is found that the charge state of the Au particle is negative in a reducing chemical environment whereas in the presence of oxidizing species coadsorbed to the oxide surface the cluster obtained a net positive charge. In the context of the well-known CO oxidation reaction, charge transfer facilitates the plasticization of Au20, which allows for a strong adsorbate induced surface reconstruction upon addition of CO leading to the formation of mobile Au-CO species on the surface.

Reconstruction of the head and neck region using lower trapezius musculocutaneous flaps.

Background: Recent literature has indicated that free flaps are currently considered the preferred choice for head and neck reconstruction. However, head and neck cancer patients are frequently treated with chemoradiotherapy, which is often associated with a poor general and local condition, and thus, such patients are ineligible for free flap reconstruction. Therefore, other reconstruction modalities should be considered.

Complete laryngotracheal separation following attempted hanging.

Laryngotracheal separation (LTS) is the most immediately life-threatening airway injury. LTS is so rare that very few otolaryngologists have experience with it. LTS is one of the diagnostic and therapeutic challenges in airway diseases and its management remains to be established.

Prediction of occult central lymph node metastasis in papillary thyroid carcinoma by preoperative BRAF analysis using fine-needle aspiration biopsy: a prospective study.

Context: Few reports have determined whether preoperative detection of the BRAF V600E mutation in fine-needle aspiration biopsy (FNAB) may influence determination of surgical extent such as prophylactic central lymph node dissection (CLND) in patients with papillary thyroid carcinoma (PTC).

Objectives: Our objectives were to investigate whether preoperative BRAF analysis may assist determination of surgical extent, including prophylactic CLND with variable clinicopathological risk factors for central lymph node metastasis, in patients with PTC and clinically node-negative neck.

Patients And Methods: From July 2009 to May 2011, we prospectively enrolled 148 PTC patients with clinically node-negative neck who received a total thyroidectomy and prophylactic CLND.

Expression of matrix metalloproteinase-12 is correlated with extracapsular spread of tumor from nodes with metastasis in head and neck squamous cell carcinoma.

Matrix metalloproteinases (MMPs) play an important role in tumor invasiveness and metastasis. The aim of this study was to investigate the expression pattern of MMPs in the primary tumor of head and neck squamous cell carcinomas (HNSCC) with cervical node metastasis and to correlate the expression of MMP in the primary tumor with the presence of extracapsular spread (ECS) in nodes with metastasis. A retrospective study was conducted.

Pattern of expression of cyclooxygenase-2 in malignant transformation of sinonasal inverted papilloma.

Objective: Cyclooxygenases (COXs) are enzymes that catalyze the conversion of arachidonic acid to prostaglandins. Many studies have suggested that COX-2, the inducible form of COX, is important in carcinogenesis. However, little is known about the pattern of expression of COX-2 in a multistep process of malignant transformation of sinonasal inverted papilloma (IP).

Clinical and histologic features of inverted papilloma-associated malignancy.

The objectives of the study were to analyze the clinical features of inverted papillomas (IP) associated with malignancy and to evaluate the correlation of tumor stage, survival and histolologic features. We conducted a retrospective review of 18 IP associated with malignancy patients. In addition, we compared histopathologic characteristics (tumor differentiation and malignant cell proportion) with clinical outcomes.

Selective dispersion of high purity semiconducting single-walled carbon nanotubes with regioregular poly(3-alkylthiophene)s.

Conjugated polymers, such as polyfluorene and poly(phenylene vinylene), have been used to selectively disperse semiconducting single-walled carbon nanotubes (sc-SWNTs), but these polymers have limited applications in transistors and solar cells. Regioregular poly(3-alkylthiophene)s (rr-P3ATs) are the most widely used materials for organic electronics and have been observed to wrap around SWNTs. However, no sorting of sc-SWNTs has been achieved before.

Is there any synergic effect for coadministration of mitomycin C and halofuginone on the skin wound healing?

Objective: This study compared the potencies of the antifibrotic agents mitomycin C (MMC) and halofuginone (HFN) and investigated whether coadministration of these agents produces synergic effects in an animal skin wound model.

Subjects And Methods: Twenty male Sprague-Dawley rats were used for this study. After a full-thickness excisional wound was made on the dorsum of each rat, each rat was treated with topical mitomycin, intraperitoneal HFN, or both.

Occult contralateral carcinoma in patients with unilateral papillary thyroid microcarcinoma.

Background: The optimal resection extent for papillary thyroid microcarcinoma (PTMC) confined within a unilateral lobe remains controversial.

Materials And Methods: We reviewed the medical records of 132 consecutive patients who underwent total thyroidectomy for the treatment of clinically unilateral PTMC between March 2005 and March 2009. The frequency, pattern, and predictive factors for occult contralateral carcinoma in these patients were analyzed with respect to the following variables: age, gender, tumor size, multifocality of primary tumor, presence of perithyroidal invasion, lymphovascular invasion or capsular invasion, presence of central lymph node metastasis, and the presence of coexistent benign nodules in the contralateral lobe based on preoperative evaluation and final pathology.

Predictive factors for ipsilateral or contralateral central lymph node metastasis in unilateral papillary thyroid carcinoma.

Objectives: To investigate the incidence and the risk factors for occult ipsilateral or contralateral central neck lymph node (LN)metastasis in patients with unilateral papillary thyroid carcinoma (PTC) and a clinically negative neck.

Summary Background Data: Elective central lymph node dissection (CLND) in patients with PTC remains controversial. There have been few prospective studies assessing accurate histopathologic information and predictive factors for the presence of metastasis to the ipsilateral or contralateral central compartment of the neck in patients with PTC and clinically negative neck nodes.

Predictive factors of level IIb lymph node metastasis in patients with papillary thyroid carcinoma.

Background: The extent of neck dissection (ND) appropriate for necks yielding clinical evidence of metastases of papillary thyroid carcinoma (PTC) is controversial. The need for level IIb lymph node (LN) dissection is particularly uncertain in view of its association with postoperative shoulder dysfunction. In the present study, we examined the frequency, pattern, and predictive factors of level IIb LN metastases in PTC patients with clinically positive lateral neck nodes.

Clinical characteristics of external auditory canal cholesteatoma in children.

Objective: The purpose of this study was to investigate the characteristics of pediatric external auditory canal cholesteatoma (EACC).

Methods: Chart review of nine children with EACC between January 1, 2000 and December 31, 2007 was performed with subsequent analysis of etiologic factors, associated symptoms, otoscopic findings, imaging features, and treatment outcomes.

Results: The average age of patients was 10.

Recurrent laryngeal nerve paralysis in patients with papillary thyroid carcinomas: evaluation and management of resulting vocal dysfunction.

Background: Recurrent laryngeal nerve paralysis (RLNP) occurs in patients with thyroid malignancy. This study prospectively evaluated vocal function and management outcomes of patients with papillary thyroid carcinomas (PTCs) and RLNP.

Methods: Of 319 PTC patients, 256 underwent total thyroidectomy with or without neck dissection, 42 underwent lobectomy, and 21 underwent reoperation for recurrent cancers.

Iatrogenic ear lobule ischemic injury from pressure dressing as an unusual complication of parotidectomy.

The use of compressive dressing is usually spread to enhance neovascularization of the dissected facial flap by elimination of dead space between the flap and the dermis in parotid surgery through facelift incision. The author reports a clinical case of compressive dressing after parotidectomy that was inappropriately performed to folding of the ear lobule, leading to ischemic injury. This iatrogenic complication resulted in the development of contracture of ear lobule and deformity of auricle.