Selective Gas-Phase Functionalization of SiO2 and SiNx Surfaces with Hydrocarbons.

Selective functionalization of dielectric surfaces is required for area-selective atomic layer deposition and etching. We have identified precursors for the selective gas-phase functionalization of plasma-deposited SiO2 and SiNx surfaces with hydrocarbons. The corresponding reaction mechanism of the precursor molecules with the two surfaces was studied using in situ surface infrared spectroscopy. We show that at a substrate temperature of 70 °C, cyclic azasilanes preferentially react with an -OH-terminated SiO2 surface over a -NHx-terminated SiNx surface with an attachment selectivity of ∼5.4, which is limited by the partial oxidation of the SiNx surface. The cyclic azasilane undergoes a ring-opening reaction where the Si-N bond cleaves upon the reaction with surface -OH groups forming a Si-O-Si linkage. After ring opening, the backbone of the grafted hydrocarbon is terminated with a secondary amine, -NHCH3, which can react with water to form an -OH-terminated surface and release CH3NH2 as the product. The surface coverage of the grafted cyclic azasilane is calculated as ∼3.3 × 1014 cm-2, assuming that each reacted -OH group contributes to one hydrocarbon linkage. For selective attachment to SiNx over SiO2 surfaces, we determined the reaction selectivity of aldehydes. We demonstrate that aldehydes selectively attach to SiNx over SiO2 surfaces, and for the specific branched aliphatic aldehyde used in this work, almost no reaction was detected with the SiO2 surface. A fraction of the aldehyde molecules reacts with surface -NH2 groups to form an imine (Si-N═C) surface linker with H2O released as the byproduct. The other fraction of the aldehydes also reacts with surface -NH2 groups but do not undergo the water-elimination step and remains attached to the surface as an aminoalcohol (Si-NH-COH-). The surface coverage of the grafted aldehyde is calculated as ∼9.8 × 1014 cm-2 using a known infrared absorbance cross-section for the -C(CH3)3 groups.

Gas Phase Organic Functionalization of SiO2 with Propanoyl Chloride.

The reaction mechanism of propanoyl chloride (C2H5COCl) with -SiOH-terminated SiO2 films was studied using in situ surface infrared spectroscopy. We show that this surface functionalization reaction is temperature dependent. At 230 °C, C2H5COCl reacts with isolated surface -SiOH groups to form the expected ester linkage. Surprisingly, as the temperature is lowered to 70 °C, the ketone groups are transformed into the enol tautomer, but if the temperature is increased back to the starting exposure temperature of 230 °C, the ketone tautomer is not recovered, indicating that the enol form is thermally stable over a wide range of temperatures. Further, the enol form is directly formed after exposure of a SiO2 surface to C2H5COCl at 70 °C. We speculate that the enol form, which is energetically unfavorable, is stabilized because of hydrogen bonding with adjacent enol groups or through hydrogen bonding with unreacted surface -SiOH groups. The surface coverage of hydrocarbon molecules is calculated as ∼6 × 1012 cm-2, assuming each reacted -SiOH group contributes to one hydrocarbon linkage on the surface. At a substrate temperature of 70 °C, the enol form is unreactive with H2O, and H2O molecules simply physisorb on the surface. At higher temperatures, H2O converts the ketone to the enol tautomer and reacts with Si-O-Si bridges, forming more -SiOH reactive sites. The overall hydrocarbon coverage on the surface can then be further increased through cycling H2O and C2H5COCl doses.

Congenital Disseminated Malignant Rhabdoid Tumor Mimicking a Vascular Lesion.

A congenital disseminated malignant rhabdoid tumor (MRT) is an exceedingly rare and aggressive pediatric cancer marked by the presence of malignant rhabdoid cells in various organs, including the brain, kidneys, and soft tissues, at birth. It is often detected prenatally or shortly post-birth. The malignancy's aggressiveness results in a bleak prognosis, offering limited treatment options and low survival rates. Early diagnosis and comprehensive medical intervention are crucial, but managing this condition is complicated by its rarity. We herein presented a case of a 37 and 1/7 week gestation male infant with a rapidly growing arm soft tissue mass within two weeks, diagnosed as an MRT. Post-delivery examinations revealed multiple lesions in the lungs, kidney, liver, and adrenal glands. Notably, chemotherapy yielded a significant improvement in the arm lesion, contrasting with other lesions showing a limited response. This observation suggests potential tumor heterogeneity, emphasizing the necessity of diverse therapeutic regimens. Our case underscores the complexities of congenital disseminated MRT, prompting a reevaluation of treatment strategies for enhanced efficacy in managing this challenging pediatric cancer.

Thermogenic hydrocarbon biodegradation by diverse depth-stratified microbial populations at a Scotian Basin cold seep.

At marine cold seeps, gaseous and liquid hydrocarbons migrate from deep subsurface origins to the sediment-water interface. Cold seep sediments are known to host taxonomically diverse microorganisms, but little is known about their metabolic potential and depth distribution in relation to hydrocarbon and electron acceptor availability. Here we combined geophysical, geochemical, metagenomic and metabolomic measurements to profile microbial activities at a newly discovered cold seep in the deep sea. Metagenomic profiling revealed compositional and functional differentiation between near-surface sediments and deeper subsurface layers. In both sulfate-rich and sulfate-depleted depths, various archaeal and bacterial community members are actively oxidizing thermogenic hydrocarbons anaerobically. Depth distributions of hydrocarbon-oxidizing archaea revealed that they are not necessarily associated with sulfate reduction, which is especially surprising for anaerobic ethane and butane oxidizers. Overall, these findings link subseafloor microbiomes to various biochemical mechanisms for the anaerobic degradation of deeply-sourced thermogenic hydrocarbons.

Attention deficit/hyperactivity disorder in adults.

Attention deficit/hyperactivity disorder (ADHD), characterized by inattention, hyperactivity/impulsivity, or a combination of these, is being increasingly recognized in adults. Adult ADHD prevalence rates range from 1% to 4%. The pathophysiology of adult ADHD is likely multifactorial, including genetic, environmental, and neurobiological influences. Though ADHD diagnostic criteria per the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) were developed based on child samples, the symptoms are believed to be similar in adults, with some developmental differences in symptom presentation. This article identifies common presenting complaints of adults who have ADHD and provides information useful for differential diagnosis of these patients. Specific strategies for pharmacological and nonpharmacological intervention are also presented.

Conscious sedation and emergency department length of stay: a comparison of propofol, ketamine, and fentanyl/versed.

STUDY OBJECTIVES: Three of the most commonly used agents for conscious sedation in the Emergency Department (ED) are ketamine, fentanyl/versed, and propofol. In this study, we measured and compared the total times spent in the ED with each of these agents. Our objective was to determine whether the use of propofol for conscious sedation was associated with a shorter length of ED stay as compared to the other two agents. METHODS: This was a consecutive case series. All patients who required procedural conscious sedation who presented to the ED at University of California, Irvine Medical Center from January 2003 through April 2004 were included in the study. The attending ED physician evaluated the patient and determined which medication(s) would be administered. All patients underwent procedural sedation according to the ED's standardized sedation protocol. The times and dosages of administered medications and the sedation/consciousness level (SCL) scores were recorded by ED nurses at 3-5 minute intervals. Data was abstracted prospectively. The time to sedation (first dose of agent to SCL score of 2 or less) and time to recovery (last dose of agent to SCL score of 4) of the different regimens were then analyzed and compared. RESULTS: Thirty-eight patients received propofol, 38 received ketamine, and 14 received fentanyl/versed. The mean times to sedation (minutes) were: propofol 4.5 (95% CI: 3.3-5.7), ketamine 10.6 (95% CI: 5.8-15.4), fentanyl/versed 11.5 (95% CI: 3.5-19.4). The mean times to recovery were: propofol 21.6 (95% CI: 16.1-27.1), ketamine 55.4 (95% CI: 46.2-64.5), fentanyl/versed 59.9 (95% CI: 20.3-99.5). Propofol had a statistically significant shorter time to sedation than both ketamine (p<.001) and fentanyl/versed (p=.022). Propofol also produced shorter recovery times than both ketamine (p<.001) and fentanyl/versed (p=.002). CONCLUSION: In this study, sedation and recovery times were shorter with propofol than with ketamine or fentanyl/versed. The use of propofol for conscious sedation in this non-randomized study was associated with a shorter ED length of stay.

Extraskeletal osteochondroma of the foot.

An extraskeletal osteochondroma is an infrequently encountered benign cartilaginous tumor with a predilection for the hands and feet that usually does not exceed 3 cm in diameter. This diagnosis can be misleading because it bears the same name as the osseous neoplasm more commonly referred to as an exostosis. The authors present an unusual case of a painful enlarging mass in the foot of a 28-year-old man who was later diagnosed as having an extraskeletal osteochondroma measuring in excess of 4 cm. Clinical, radiographic, and magnetic resonance images are provided along with intraoperative and histopathologic figures. There was no sign of recurrence 1 year after surgical excision. A review of the literature regarding this uncommon lesion is also presented.