Enhancing single-wall carbon nanotube properties through controlled endohedral filling.

Chemical control of the endohedral volume of single-wall carbon nanotubes (SWCNTs) via liquid-phase filling is established to be a facile strategy to controllably modify properties of SWCNTs in manners significant for processing and proposed applications. Encapsulation of over 20 different compounds with distinct chemical structures, functionalities, and effects is demonstrated in SWCNTs of multiple diameter ranges, with the ability to fill the endohedral volume based on the availability of the core volume and compatibility of the molecule's size with the cross-section of the nanotube's cavity. Through exclusion of ingested water and selection of the endohedral chemical environment, significant improvements to the optical properties of dispersed SWCNTs such as narrowed optical transition linewidths and enhanced fluorescence intensities are observed. Examples of tailoring modified properties towards applications or improved processing by endohedral passivation are discussed.

The tree BVOC index.

Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes in BVOC emissions are calculated as the result of transitioning to a lower-emitting species mix in future planting. A simplified method for calculating the emissions reduction and a Tree BVOC index based on the calculated reduction is described. An example illustrates the use of the index as a tool for implementation and monitoring of a tree program designed to reduce BVOC emissions as a control measure being developed as part of the State Implementation Plan (SIP) for the Sacramento Federal Nonattainment Area.

Dielectric response of aligned semiconducting single-wall nanotubes.

We report measurements of the full intrinsic optical anisotropy of isolated single-wall carbon nanotubes (SWNTs). By combining absorption spectroscopy with transmission ellipsometry and polarization-dependent resonant Raman scattering, we obtain the real and imaginary parts of the SWNT permittivity from aligned semiconducting SWNTs dispersed in stretched polymer films. Our results are in agreement with theoretical predictions, highlighting the limited polarizability of excitons in a quasi-1D system.

Comparative measures of single-wall carbon nanotube dispersion.

Model composites of DNA-wrapped single-wall carbon nanotubes in poly(acrylic acid) are used to evaluate metrics of nanotube dispersion. By varying the pH of the precursor solutions, we introduce a controlled deviation from ideal behavior. On the basis of small-angle neutron scattering, changes in near-infrared fluorescence intensity are strongly correlated with dispersion, while optical absorption spectroscopy and resonant Raman scattering are less definitive. Our results represent the first systematic comparison of currently accepted measures of nanotube dispersion.

High temperature ferromagnetism with a giant magnetic moment in transparent co-doped SnO(2-delta).

The occurrence of room temperature ferromagnetism is demonstrated in pulsed laser deposited thin films of Sn(1-x)Co(x)O(2-delta) (x<0.3). Interestingly, films of Sn(0.95)Co(0.05)O(2-delta) grown on R-plane sapphire not only exhibit ferromagnetism with a Curie temperature close to 650 K, but also a giant magnetic moment of 7.5+/-0.5 micro(B)/Co, not yet reported in any diluted magnetic semiconductor system. The films are semiconducting and optically highly transparent.

Exchange interaction effects on the optical properties of LuMnO3.

We have measured the optical conductivity of single crystal LuMnO3 from 10 to 45000 cm(-1) at temperatures between 4 and 300 K. A symmetry allowed on-site Mn d-d transition near 1.7 eV is observed to blueshift ( approximately 0.1 eV) in the antiferromagnetic state due to Mn-Mn superexchange interactions. Similar anomalies are observed in the temperature dependence of the TO phonon frequencies which arise from spin-phonon interaction. We find that the known anomaly in the temperature dependence of the quasistatic dielectric constant epsilon(0) below T(N) approximately 90 K is overwhelmingly dominated by the phonon contributions.

Intensity-modulated radiation therapy reduces late salivary toxicity without compromising tumor control in patients with oropharyngeal carcinoma: a comparison with conventional techniques.

BACKGROUND AND PURPOSE: Intensity-modulated radiation therapy (IMRT) offers superior dosimetric conformity for normal tissue sparing in patients with oropharyngeal cancer. In this study, acute and late toxicity, and tumor control were compared between conventional beam arrangement (CRT) and IMRT. MATERIALS AND METHODS: Between January 1970 and December 1999, 430 patients with carcinoma of the oropharynx were treated at the Mallinckrodt Institute of Radiology. There were 260 patients with tonsil primary tumors and 170 patients with tumors arising from the base of the tongue. Twenty-four (6%) patients had stage I disease, 88 (20%) had stage II, 128 (30%) had stage III, and 190 (44%) had stage IV disease. Patients were divided into five treatment groups. Group I consisted of 109 patients who received preoperative CRT. Group II consisted of 142 patients who received postoperative CRT. Group III consisted of 153 patients who received definitive CRT. Inverse planning IMRT (Peacock, NOMOS) was used to treat 14 patients postoperatively (Group IV) and 12 patients definitively without surgery (Group V). Acute and late normal tissue side-effects were scored according to the Radiation Therapy Oncology Group radiation morbidity criteria. The median follow-up was 3.9 years. RESULTS: The 2-year local-regional control values for the five studied groups were 78, 76, 68, 100 and 88%, respectively. The 2-year disease-free survival values for the five studied groups were 68, 74, 58, 92 and 80%, respectively. IMRT significantly reduced the incidence of late xerostomia. CONCLUSIONS: When IMRT was compared with conventional techniques, the dosimetric advantage of IMRT did translate into a significant reduction of late salivary toxicity in patients with oropharyngeal carcinoma. No adverse impact on tumor control and disease-free survival was observed in patients treated with IMRT.

Esthesioneuroblastoma: the impact of treatment modality.

BACKGROUND: We evaluated the impact of treatment modality on esthesioneuroblastoma. METHODS: Between 1976 and 1996, 25 patients with esthesioneuroblastoma were treated at Mallinckrodt Institute of Radiology. There were 11 male and 14 female patients; their ages ranged from 16 to 73 years (median, 57 years). The tumors were Kadish stage A in 3, Stage B in 13, C in 8, and modified D in 1 (cervical nodal metastasis). Seventeen patients were treated with surgery and radiation therapy, six were treated with irradiation alone, and two were treated with surgery only. Eight patients received neoadjuvant chemotherapy. Median follow-up was 8 years (range, 2-24 years). RESULTS: The 5-year actuarial overall survival, disease-free survival, and local tumor control rates were 66.3%, 56.3%, and 73.0%, respectively. Kadish stage was not a significant prognosticator for local control or disease-free survival. Five-year local control rates were 87.4% for the combination of surgery and radiation therapy and 51.2% for irradiation alone. Two patients with Kadish stage A and B disease underwent surgical resection alone; both failed locally. In contrast, 33.3% of patients (three of nine) with Kadish stage A or B disease who received adjuvant radiation therapy had a local recurrence develop. With adjuvant radiation therapy, the surgical margin status did not influence local tumor control. Among the eight patients who received neoadjuvant chemotherapy, six patients showed no response, one had partial response, and one showed a complete response. CONCLUSIONS: Surgical resection plus adjuvant radiation therapy yielded the best treatment outcome. More effective chemotherapy agents with a reproducible effectiveness are needed for patients with locally advanced esthesioneuroblastoma.

Cancer of retromolar trigone: long-term radiation therapy outcome.

BACKGROUND: Cancer of the retromolar trigone is an uncommon head and neck cancer. In this retrospective study, we identified the prognostic factors and evaluated the therapeutic outcomes of patients treated with preoperative radiation therapy (RT), postoperative RT, and RT alone. METHODS: Between 1971 and 1994, 65 patients with histologically proven epidermoid carcinoma of the retromolar trigone were treated at the Mallinckrodt Institute of Radiology; 10 patients received preoperative RT (30-55.2 Gy), 39 received postoperative RT (46-66.6 Gy), and 15 were treated with RT alone (63-74 Gy). Surgery included 44 composite resections and 7 wide excisions. The minimum follow-up was 5 years. RESULTS: The 5-year disease-free survival rates were 90% with preoperative RT, 63% with postoperative RT, and 31% with RT alone. The 5-year disease-free survival rates were 76% for patients with T1 disease, 50% for T2, 72% for T3, and 54% for T4. The 5-year disease-free survival rates were 69% for patients with NO disease, 56% for N1, and 26% for N2. The locoregional recurrence rates were 10% (1 of 10) for preoperative RT, 23% (9 of 39) for postoperative RT, and 44% (7 of 16) for RT alone. On multivariate analysis, the significant factors for disease-free survival were treatment modality (p =.002) and N stage (p =.012); for locoregional control it was treatment modality (p =.046); and for distant metastasis it was N stage (p =.002). The incidence of bone necrosis, soft tissue necrosis, and severe trismus was 12% with postoperative RT, 11% with RT alone, and none with preoperative RT. CONCLUSIONS: Combination surgery with postoperative or preoperative RT offers better locoregional control and disease-free survival than RT alone for epidermoid carcinoma of the retromolar trigone. Lymph node status significantly influences the disease-free survival and distant metastasis rates.

Emotion-induced changes in human medial prefrontal cortex: I. During cognitive task performance.

Regional cerebral blood flow (BF) was examined in regions of the medial prefrontal cortex (MPFC) with positron-emission tomography while subjects performed two cognitive tasks, reading nouns aloud and generating appropriate verbs for the same nouns. The control task was passive viewing of the same words. BF was reduced in regions of the MPFC during word reading and naive verb generation, relative to a control state in which the subjects passively viewed nouns. Practicing verb generation produced improved performance, as measured by response time, which was strongly correlated with further reductions in MPFC and hypothalamic BF. After practice, when verb generation was performed on a novel list of words, reaction times slowed and the pattern of MPFC BF reverted to that seen in the word reading and naive conditions. A separate behavioral study of the verb-generation task indicated that anxiety, high during naive use-generation as measured by heart rate and self-report, decreased with practice on the task but returned with the introduction of a novel list of words. Taken together, these results suggest that the MPFC is part of a network, including the hypothalamus and brainstem, whose activity reflects a dynamic interplay between cognitive task performance and emotion.

Emotion-induced changes in human medial prefrontal cortex: II. During anticipatory anxiety.

Regional cerebral blood flow (BF) was examined in the human medial prefrontal cortex (MPFC) with positron emission tomography during anticipatory anxiety. Transient anxiety was induced in normal subjects by having them anticipate a painful shock to the fingers of one hand. BF was decreased during anticipatory anxiety, relative to an eyes-closed resting condition, in two regions of the MPFC (Brodmann Areas 10/32 and 24/25). BF decreases in these areas were inversely correlated with anxiety self rating, such that the least anxious subjects exhibited the largest BF reductions, whereas the most anxious subjects showed no significant BF reduction or a slight increase. BF changes in MPFC and in the midbrain were correlated with each other and with anxiety self rating. These results are consistent with the hypothesis that BF reductions in MPFC, previously observed in cognitive tasks, reflect a dynamic balance between focused attention and subject anxiety and may occur from a functionally active baseline or default state. The characterization of such relationships within the human brain enables new insights into the integration of cognition and emotion.

The emotional modulation of cognitive processing: an fMRI study.

The functional neuroanatomy of visual processing of surface features of emotionally valenced pictorial stimuli was examined in normal human subjects using functional magnetic resonance imaging (fMRI). Pictorial stimuli were of two types: emotionally negative and neutral pictures. Task performance was slower for the negatively valenced than for the neutral pictures. Significant blood oxygen level dependent (BOLD) increases occurred in the medial and dorsolateral prefrontal cortex, midbrain, substantia innominata, and/or amygdala, and in the posterior cortical visual areas for both stimulus types. Increases were greater for the negatively valenced stimuli. While there was a small but significant BOLD decrease in the subgenual prefrontal cortex, which was larger in response to the negatively valenced pictures, there was an almost complete absence of other decreases prominently seen during the performance of demanding cognitive tasks [Shulman, G. L., Fiez, J. A., Corbetta, M., Buckner, R. L., Miezin, F. M., Raichle, M. E., & Petersen, S. E. (1997). Common blood flow changes across visual tasks: II. Decreases in cerebral cortex. Journal of Cognitive Neuroscience, 9, 648--663]. These results provide evidence that the emotional valence and arousing nature of stimuli used during the performance of an attention-demanding cognitive task are reflected in discernable, quantitative changes in the functional anatomy associated with task performance.

Stage I (T1 N0 M0) squamous cell carcinoma of the laryngeal glottis: therapeutic results and voice preservation.

BACKGROUND: The therapeutic outcomes for voice preservation in Stage I (T1 N0 M0) glottic carcinoma, treated with conservation surgery, radiation therapy, and endoscopic resection, are controversial. METHODS: A retrospective tumor registry retrieval of data on patients treated with curative intent at Washington University Medical Center-Barnes Hospital between January 1971 and December 1990 for the surgical group, January 1971 to December 1985 for the low-dose radiation group, and January 1986 to January 1995 for the high-dose radiation group, was performed. RESULTS: The 659 patients with Stage I (T1 N0 M0) glottic carcinoma treated with curative intent were subdivided into four groups: (1) 90 patients received low-dose radiation (mean dose 58 Gy, range 55-65 Gy, daily fractionation 1.5-1.8 Gy); (2) 104 patients received high-dose radiation (mean dose 66.5 Gy, range 65-70 Gy, daily fractionation 2-2.25 Gy); (3) 404 patients underwent conservation surgery; and (4) 61 patients had endoscopic resection. T1A (85%) and T1B (15%) disease was equally distributed among the groups. The anterior commissure was involved in 38 patients in the radiation therapy groups and 56 patients in the surgical groups. The overall local control was 89%. The overall local salvage was 84%. The overall unaided laryngeal voice preservation was 90%. The overall 5-year disease specific and actuarial survival rates were 95% and 81%, respectively. Prevalence of 2% regional metastases, 1.2% distant metastases, and 14% second primary malignancies were documented. The cure rate was 69% for regional metastases, 13% for distant metastases, and 44% for second primary malignancies. There were 5 complication deaths (0.1%), and 38 (6%) patients died of intercurrent disease. The use and dose of tobacco products was significantly increased in patients who died of intercurrent disease (p = 0.004) or developed second primary malignancies (p = 0.024). No significant difference was observed among the four therapeutic groups in the 5-year cause-specific survival rate (p, 0.68). Actuarial survival was significantly decreased in the low-dose radiation therapy group as compared with the other three therapeutic groups (p = 0.04). Initial local control was poorer for the endoscopic (77%) and low-dose radiation (78%) groups as compared with the high-dose radiation (89%) and conservation surgery (92%) groups (p = 0.02) but significant differences were not found for ultimate local control following salvage treatment. Unaided laryngeal voice preservation was similar for high-dose radiation (89%), conservation surgery (93%) and endoscopic resection (90%), but significantly poorer for low-dose radiation (80%; p = 0.02). T1B disease (N = 94) had similar local control and voice preservation with conservation surgery (87%) and high-dose radiation (88%) but lower results with low-dose radiation and endoscopic resections (67% unaided laryngeal voice preservation; p = 0.02). CONCLUSION: (1)The four therapeutic groups achieved similar rates of disease specific survival and ultimate local control. (2) Low-dose radiation was associated with significantly lower overall actuarial survival and unaided laryngeal voice preservation. (3) Endoscopic resection was associated with a significantly lower initial local control rate, but following salvage therapy achieved equivalent results to the other treatment methods. (4) Patients with (T1 N0 M0) glottic carcinoma had similar survival, local control, and unaided laryngeal voice preservation rates with high-dose radiation, conservation surgery, and endoscopic resections, but not with low-dose radiation therapy. (c) 1999 John Wiley & Sons, Inc. Head Neck 21: 707-717, 1999.

Management of stage II (T2N0M0) glottic carcinoma by radiotherapy and conservation surgery.

BACKGROUND: The best therapeutic approach for the treatment of stage II (T2N0M0) glottic carcinoma is controversial. METHODS: A retrospective tumor registry data retrieval of patients with stage II glottic carcinoma treated with curative intent at Washington University Medical Center-Barnes Hospital between January 1971 and December 1989 (surgery) and December 1995 (radiotherapy) was performed. RESULTS: Among 134 patients with stage II glottic carcinomas treated with curative intent and function preservation, there were 47 patients treated with low dose radiotherapy (median dose, 58.5 Gy at 1.5-1.8 Gy daily fractions), 16 patients with high dose radiotherapy (67.5-70 Gy) at higher daily fractionation doses (2-2.25 Gy), and 71 patients underwent conservation surgery. The overall local control rate was 85%. The overall salvage rate was 68%. The 5-year actuarial and disease specific survivals were 81.5% and 92%, respectively. Unaided phonation was achieved in 84.4% of the patients. An incidence of 10.4% regional metastases, 2.2% distant metastases, and 6% second primary tumors was documented. There were no statistical differences in local control, voice preservation, and 5-year actuarial and disease specific cure rates between conservation surgery and high dose radiation (p = .89). Low dose radiation had statistically lower local controls, 5-year survival, and voice preservation (p = .014). In advanced T2B disease, treating the ipsilateral neck nodes reduced regional metastases (p = .02). CONCLUSIONS: High dose and daily fractionation (70 Gy at 2 Gy daily fraction doses) radiation achieved results equivalent to those of conservation surgery in 5-year local control, survival, and voice preservation. In advanced T2B disease, treatment of the ipsilateral neck nodes by radiotherapy or functional neck dissection reduced regional metastases.

Symptoms as an index of biologic behavior in head and neck cancer.

The TNM staging system for head and neck cancer is based on the morphologic description of the tumor and disregards the clinical condition of the patient. Cancer symptoms were evaluated as a biologic index of disease to improve survival estimates. The medical records of 1010 patients receiving initial cancer treatment between 1980 and 1991 were retrospectively reviewed. The mean survival duration was 62 months for the entire population. By use of SAS statistical software (SAS Institute, Cary, NC), 48 symptom variables were screened by univariate analysis, and 23 of these variables were selected for entry into a Cox proportional hazards model on the basis of survival duration. Dysphagia, otalgia, neck lump, and weight loss were identified as independent predictors of survival duration (P < 0.01). A composite symptom-severity staging system was created on the basis of the 4 symptoms. Mean survival duration (95% CI) by symptom-severity stage was as follows: none, 74 months (70 to 79 months); mild, 56 months (51 to 61 months); moderate, 40 months (33 to 47 months); and severe, 31 months (22 to 41 months) (chi 2 = 30.8, P = 0.0001). Survival duration by TNM stage was as follows: I, 89 months (82 to 95 months); II, 71 months (65 to 78 months); III, 53 months (47 to 59 months); and IV, 42 months (37 to 47 months) (chi 2 = 56.2, P = 0.0001). When symptom-severity stage was entered in a proportional-hazards model along with TNM stage, comorbidity, age, and alcohol use, all 5 variables were independently predictive of survival duration (risk ratio: symptom severity 1.28, TNM 1.33, comorbidity 1.80, age 1.47, alcohol use 1.09). Appropriately defined symptom variables contain important prognostic information, which is independent of the TNM system. Therefore symptoms provide an index of biologic behavior in head and neck cancer.

Clinical-severity staging system for oral cavity cancer: five-year survival rates.

The objective of this research is to improve the classification and survival estimates for patients with oral cavity cancer by combining cancer symptom severity and comorbidity with the current TNM staging system. The study design is a retrospective medical record review that uses explicit coding criteria. The medical records of 277 patients receiving initial treatment at the Washington University Medical Center between 1980 and 1989 were reviewed. Multivariate analysis identified patient factors that significantly affected 5-year survival. These patient factors, symptom severity and comorbidity, were combined with TNM to create a composite clinical-severity staging system. The overall 5-year survival rate was 46% (128/277). Survival rates by TNM stage were as follows: stage I, 72% (36/50); II, 54% (45/84); III, 37% (24/65); and IV, 29% (23/78) (chi2 = 25.27, P = 0.001). When patients were grouped according to the clinical-severity staging system, survival rates were as follows: stage I, 77% (33/43); II, 56% (45/80); III, 42% (43/103); and IV, 14% (7/51) (chi2 = 40.62, P = 0.001). Survival estimates can be improved by adding carefully studied and suitably defined patient variables to the TNM system. The current TNM staging system for oral cavity cancer is based solely on the morphologic description of the tumor and disregards the clinical condition of the patient. Patient factors, such as cancer symptom severity and comorbidity, have a significant impact on survival. Continued exclusion of patient factors leads to imprecision in prognostic estimates and hinders interpretation of clinical studies.