bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmid Gene Delivery into Rat Laryngeal Muscle Using Bidirectional Electroporation
Authors: Flint Paul W , Saito Koichiro , Lehar Mohamed , Li Zhao Bo
Published: August 2004

Problem

Nonviral gene delivery systems have advantages over viral delivery systems in several aspects including easy propagation on a large scale with high quality, and low immunogenicity. The major drawback of plasmid DNA as a vector is its low efficiency for gene transfer. In this study we examined the delivery of plasmid DNA into laryngeal muscle using electroporation in both unidirectional and bidirectional modalities to enhance gene transfer in laryngeal muscle.

Methods

Using a midline thyrotomy approach in adult Sprague‐Dawley rats, EGFP‐N3 plasmid vector was injected into the left thyroarytenoid muscle. We compared 3 groups as follows: (1) plasmid injection without electroporation, (2) plasmid injection with unidirectional electroporation, and (3) plasmid injection with bidirectional electroporation. The animals were kept alive for 1 week after the injection. Fresh frozen coronal sections of the larynx were used to assess the maximum number of thyroarytenoid muscle fibers expressing EGFP.

Results

All groups undergoing electroporation demonstrated increased EGFP expression in the muscle fibers compared to the group without electroporation. Gene expression by total number of cells was increased 2‐fold in the bidirectional group when compared to the unidirectional group.

Conclusion

Both unidirectional and bidirectional electro‐poration significantly improved the gene transfer of naked plasmid DNA in laryngeal muscle, with bidirectional electro‐poration yielding a 2‐fold increase over the unidirectional modality.

Significance

Electroporative gene transfer using bidirectional modality may improve our ability to deliver trophic factors into laryngeal muscle at lower field strengths, while avoiding the potential adverse effects of viral vectors.

Support

None reported.
The Effect of Hyaluronic Acid on Tracheal Wound Healing
Authors: LoSavio Phillip Samuel , Walner David L , Williams James M , Kaiser Kelly A , Mark Victoria , Caldarelli David D
Published: August 2004

Problem

Various methods have been studied to improve tracheal healing after surgery. Previous experiments have demonstrated the benefits of hyaluronic acid (HA) not only in wound healing in the tympanic membrane, skin, and articular cartilage but also in decreasing adhesions in abdominal operations. The goal of this project was to study the effects of hyaluronic acid on tracheal wound healing.

Methods

Twenty‐two New Zealand white rabbits, (11 experimental, 11 control) had a 2 mm round defect created in the third tracheal ring. The experimental group had an 8 mm round sodium hyaluronate‐based sponge (SEPRAPACKTM) fixed over the defect using fibrin glue (HemaseelTM). The control group had a plain 8 mm collagen sponge placed in a similar manner. Tracheal tissue was harvested at 4 weeks postop and histologically scored in regard to inflammation, connective tissue organization, epithelial closure, chondrocyte death, and cartilage regeneration (clonal cell formation) at the area of injury. Statistical analysis was done using the Mann‐Whitney U and Fisher‐Exact tests.

Results

Inflammatory cell infiltration was significantly increased at the area of injury in the control group compared to the HA‐treated wound (P = 0.014). In the HA‐treated group a lower percentage of animals had chondrocyte death at the wound edge (45.5%−HA vs 81.8%−control) (P = 0.183) and a greater percentage of animals demonstrated new clonal cell formation (72.7%−HA vs 54.5%−control) (P = 0.659). No differences were seen in connective tissue organization and epithelial closure.

Conclusion

These results show that HA significantly decreases inflammation in tracheal wounds in a rabbit model. Although not statistically significant, the results also suggest that HA may be chondroprotective, as demonstrated in articular cartilage models.

Significance

Poor wound healing including cartilage ring damage can contribute to airway compromise especially in an infant after tracheal surgery. This experiment suggests that HA may be useful as an adjunct in improving postoperative tracheal repair.

Support

(1) The Friedberg Research Fund in the Department of Otolaryngology at Rush University Medical Center. (2) SEPRAPACKTM and Hemaseel TM were both donated by GYRUS ENT and HAEMACURE, respectively under no obligation by the authors.
Distinguishing Edema vs Scar in the Rabbit Subglottis Using Optical Coherence Tomography
Authors: Karamzadeh Amir M , Jackson Ryan , Guo Shuguang , Ahuja Gurpreet S , Chao Michael Chung‐Yaw , Chen Zhongping , Wong Brian J
Published: August 2004

Problem

In neonates, subglottic stenosis is a tremendous problem related to prolonged enotracheal intubation. Despite the use of diagnostic endoscopy, differentiating between edema, scar, or neocartilage formation remains a challenge. Optical Coherence Tomography (OCT) is an imaging modality that uses light to produce high‐resolution cross‐sectional images in tissue. Using an ex vivo rabbit laryngotracheal model, we evaluate the efficacy of OCT to differentiate between several simulated subglottic pathologies.

Methods

Seven laryngeal‐tracheal complexes were harvested from freshly sacrificed rabbits. The specimens were divided into 4 groups: (1) control; (2) submucosal collagen injection (simulating scar formation); (3) dehydration/hydration (simulating edema); and (4) repeated intubation trauma. The subglottic region was imaged using an OCT system that produced images with axial and lateral resolution of 10 and 20 μm, respectively. The submucosal thickness (basement membrane to perichondrium) was measured in each group and compared to controls. OCT images were later correlated with conventional histology.

Results

The epithelium, basement membrane, lamina propria, perichondrium, and cartilage (cricoid and tracheal) were very clearly imaged. A 50% increase in submucosal thickness was observed in group 2, and the collagen was clearly identified and distinct from surrounding native tissues. Dehydration (group 3) produced a 60% reduction while rehydrating the same specimen in distilled water resulted in a 350% increase. Edema, produced by either repeated intubation or distilled water immersion, was easily differentiated from both native and the collagen‐injected tissues.

Conclusion

OCT successfully identifies the layer micro‐structure of the subglottis and can be used to differentiate between edema and increased collagen in the rabbit model.

Significance

OCT can be readily adapted for use during rigid and flexible endoscopy. Likewise, since OCT imaging fibers can be placed within endotracheal tubes to image the airway, the technique is an extremely attractive option for use in the ICU to manage the neonatal airway.

Support

None reported.
Our Experience in Endoscopic CO2 Laser Surgery for Supraglottic Carcinoma
Authors: Cotulbea Stan , Poenaru Marioara , Doros Caius , Lupescu Stelian , Iovanescu Gheorghe , Marin Alin Horia , Stefanescu Horatiu
Published: August 2004

Objectives

This study presents the indications, general principles, contraindications, limits, and results of this modern therapeutic method. Supraglottic laryngeal carcinoma is an aggressive, with high tendency for nodal metastasis. Therefore early detection and effective treatment is of outmost importance. Open surgical procedures, primary radiotherapy, and endoscopic procedures are therapeutic alternatives, with or without neck dissection and adjuvant radiotherapy.

Methods

Between 1998‐2002, 24 patients with supraglottic carcinoma T1 or T2 and N0 have been treated with supraglottic laryngectomy with CO2 laser. All patients were carefully selected using modern videoendoscopical procedures and CT scan or neck ultrasonography. Careful preoperative selection is of outmost importance for the clinical patients outcome. In the studied group, we applied horizontal supraglottic laryngectomy in 20 cases T2N0 and epiglottectomy in 4 cases T1N0. Postoperative follow‐up was between 12‐48 months (average, 36 months). The thracheostomy and nasogastric tube were not necessary in any case.

Results

In our group we obtained the following oncological results: no evidence of disease (NED) 19 cases (79.17%), and local recurrence in 5 cases (20.83%). All patients who presented local recurrence were stage T2N0; the salvation treatment we applied consisted in total laryngectomy. Immediate functional results were very good in all cases.

Conclusions

Endoscopic CO2 laser microsurgery appears to be an effective and safe alternative treatment for T1‐T2, N0 supraglottic carcinoma, with superior oncological and functional results than the other techniques, requiring short hospitalization, no tracheostomy and feeding tube, and providing superior rehabilitative result with a good quality of life.
CO2 Laser Microsurgery for Tis, T1, and Selected Cases of T2 Glottic Carcinoma
Authors: Puxeddu Roberto , Ledda Gian Peppino
Published: August 2004

Objectives

To define the oncologic efficacy of transoral endoscopic CO2 laser surgery in early glottic carcinoma.

Methods

Retrospective study of 103 patients with well to undifferentiated glottic carcinoma (14 Tis, 68 pT1a, 14 pT1b, and 7 pT2 with impairment of vocal cord mobility) were treated from October 1993 to June 2001 at the Section of Otorhinolaryngology at the Department of Surgical Sciences and Organ Transplantations of Cagliari University, Italy. Mean follow‐up was 3.9 years. Surgical treatment included endoscopic CO2 laser cordectomies from type I to type Vc, according to the classification proposed by the European Laryngological Society in 2000.

Results

According to the Kaplan‐Meier method, the probability of remaining free of local recurrence 3 years after primary surgery was 100% for the Tis group, 93.4% for the T1 group (SE 3.85%) and 100% for the T2 group. Local control at 3 years after exclusive CO2 laser salvage surgery was 94.95% (SE 3.54%). The probability of remaining free of local recurrence 3 years after any type of salvage surgery was 100% for all the classes. Laryngeal preservation was achieved in 100% of the cases. Anterior commissure spread resulted in a not statistically significant difference in local control (P = 0.6), between the group of patients without (96.54%; SE 2.43%) and with anterior commissure involvement (87.5%; SE 11.69%).

Conclusions

According to our experience, endoscopic CO2 laser surgery is an efficacious treatment for early stage glottic cancer.
Cysts, Sulcus Vocalis, and Mucosal Bridges of the Vocal Fold and Their Association with Polyps
Authors: Sakae Flavio Akira , Sasaki Fernando , Sennes Luis Ubirajara , Imamura Rui , Tsuji Domingos H
Published: August 2004

Objectives

Polyps are common lesions of vocal folds. Phonotrauma is related to physiopathology of this lesion. The objective of our study was to analyze the association with polyps and other benign vocal fold lesions (BVFLs).

Methods

Sixty‐eight patients underwent microlaryngeal surgery due to polyps of vocal folds. We analyzed retrospectively the presence of polyps in association with sulcus vocalis, cysts, and mucosal bridges.

Results

The presence of BVFLs associated with polyps occurred in 14 (20.5%) patients. In 8 (57%) patients the polyp was associated with sulcus vocalis, in 4 (29%) with vocal fold cyst and in 2 (14%) with mucosal bridge. BVFLs was contralateral to the polyp in 9 (64%) patients (6 sulcus and 3 cysts).

Conclusion

The association between polyps and others BVFLs is relatively frequent (20.5%). The polyp appears to arise from alterations in vocal fold vibration caused by the ipsilateral BVFL or as a result of repeated trauma of the contralateral BVFL.
The Effects of Ototopical Steroid, NSAID, and Antihistamine on Rat Auditory Function
Authors: Cutler Jeffrey Lyle , Hackett Troy A , Labadie Robert F
Published: August 2004

Objectives

Ototopical application of medication for the treatment of a variety of otologic disorders is becoming commonplace. With the increased use of ototopical agents, auditory toxicity must be analyzed. Our objective was to study the effects of transtympanic injection of steroid, NSAID, or antihistamine on Sprague‐Dawley rat auditory function.

Methods

Twelve Sprague‐Dawley rats had their auditory function assessed through ABR. The rats were randomly divided into 6 groups (n = 2 each group): dexamethasone, rimexalone, patanol, astelin, diclofenac, and gentamycin (positive control). Baseline ABR were recorded prior to transtympanic injection and again recorded at 1 and 7 days after treatment. Wave 1 latency and amplitude were measured at 80, 60, 40, and 20 dB using click stimulus. The gentamycin group received an additional 10 days of intramuscular gentamycin after the initial treatment in order to demonstrate significant latency shift.

Results

The steroid, antihistamine, and NSAID groups did not demonstrate shifts in wave 1 latency at postinjection day 1 or 7. The gentamycin group revealed a significant latency shift and decrease in amplitude at 40 and 20 db on postinjection day 1. Ten days of intramuscular gentamycin significantly shifted the latency of wave 1 compared to pretreatment.

Conclusion

Single dose steroid, NSAID, and antihistamine do not demonstrate a significant ABR latency shift. Transtympanic gentamycin causes a temporary latency shift and amplitude reduction at low intensity stimulus with a return in function at 1 week posttreatment. Performing ABR in the Sprague‐Dawley rat is an excellent model to assess auditory toxicity from transtympanic injection.
Analysis of RET Gene Point Mutation in a Family with Familial Medullary Thyroid Cancer
Authors: Dae Lee Kang , Mun Hyo Sung , Noguchi Shiro
Published: August 2004

Objectives

Hereditary medullary thyroid cancer is presented as part of MEN 2A or MEN 2B, but can also be inherited alone, which is called familial medullary thyroid cancer(FMTC). Author sought to detect point mutation of RET proto‐oncogene by using molecular genetic method on the family line of FMTC.

Methods

DNA was extracted from the peripheral blood leukocyte of 6 medullary thyroid cancer patients (5 assumed sporadic and 1 assumed FMTC). After PCR amplification of exon 10, 11, 13, 14, 15, 16, point mutation of RET protooncogene was investigated using DNA sequence analyzer. When point mutation was identified in index patient of FMTC, same genetic study was conducted in their family

Results

We identified point mutation of TGC(Cys)æCG‐C(Arg) at codon 618 of RET proto‐oncogene exon 10 in 1 assumed FMTC patient. The same point mutation was detected in 4 of the 9 family members. Among them, index patient and her mother had biochemical and clinical symptoms and underwent total thyroidectomy and neck dissection. Operations are scheduled for remaining members with point mutation later on.

Conclusion

Genetic analysis of RET proto‐oncogene will overcome the limitations of classic calcitonin stimulation test and make the earlier diagnosis and treatment of FMTC be possible.
Evaluation of Postoperative Morbidity in Pediatric Tonsillectomy with Sucralfate
Authors: Sampaio Fernando , Oliveira Carlos A
Published: August 2004

Objectives

To evaluate the efficacy of sucralfate in alleviating posttonsillectomy morbidity in a pediatric group of patients

Methods

A prospective double‐blind, randomized, and controlled study comparing the irrigation of a solution containing either 1 g of sucralfate or 1 g of lactose was conducted on 58 children undergoing tonsillectomy, after the purpose and method of study were described to the parents, at Brasilia University Hospital. The anesthetic was standardized and no premedication was used; no analgesic drugs were used during the procedure. Tonsillectomy was performed using cold dissection by the same attending surgeon. Each patient used the same solution to swish and swallow 4 times daily during 7 days. Pain using Mcgraft analogue scale, vomiting and bleeding, time to return to normal diet, analgesic drugs intake, changes in the weight and temperature and interincisor teeth distance were assessed by the same author 6, 12 hours, and 7 days after the surgery. Results were compared between groups using t test and P value was considered statistic significant when it was less than 0.05.

Results

We evaluated 29 children in each group with ages ranging from 3 to 12 years (mean, 6,2). We found no demographic difference between the groups. No patient was excluded from the study. No statistic difference between the groups was found comparing the parameters above, as well as, no difference was found in the evolutive assessment of the face scale for pain between the groups.

Conclusion

Sucralfate showed no benefice in alleviating posttonsillectomy morbidity in this group of patients.
Rhinoscleroma: A Case Report and Update on Medical and Surgical Management
Authors: Drawert Casey , Simpson C Blake , Velazquez Ruben , McGuff Howard S
Published: August 2004

Objectives

Rhinoscleroma is a chronic, progressive, granulomatous infection caused by Klebsiella rhinoscleromatis. The bacteria can infect the upper and/or lower airways, with the sinonasal cavity being affected 95%‐100% of the time. We present the case of a 42‐year‐old Hispanic man who presented with Stage 3 rhinoscleroma, resulting in nasopharyngeal, glottic, and subglottic stenosis.

Methods

The patient was taken to the operating room for direct microlaryngoscopy. A posterior cordotomy of the left vocal fold and laser radial incisions/dilation of the subglottis were performed along with topical application of Mitomycin‐C.

Results

Biopsies of the nasopharygeal and subglottic lesions showed inspissated mucin with foamy histiocytes, gram negative bacilli, and acute and chronic inflammation with fibrosis. Cultures were positive for Klebsiella rhinoscleromatis, sensitive to gatifloxacin. These pathological findings were consistent with Stage 3 rhinoscleroma. The patient was treated with a 6‐month course of gatifloxacin. Purulent rhinorrhea and airway difficulties were improved at 6 weeks and resolved at 6 months.

Conclusion

We report a case of synchronous rhinoscleromatous lesions. A combination treatment of surgical laser debridement, Mitomycin‐C and long‐term fluoroquinolones appears to be effective in treating this condition. There are 3 stages of rhinoscleroma and with prompt recognition and early treatment, the natural history of the disease can be halted. The advantages of fluoroquinolones over traditional antibiotic treatment for this condition (tetracycline) include low incidence of side effects, once daily dosing and concentration within the macrophages, the region of bacterial replication. When surgical treatment is necessary, stenosis can be effectively managed with CO2 laser treatments and Mitomycin‐C.
A Rare Case Report about Noma or Cancrum Oris Occurring in a Neutropenic Patient
Authors: Majmundar Kshitij V , Heller Andrew J
Published: August 2004

Objectives

To discuss the etiology, diagnosis, and management of Noma, a rare and devastating disease of the facial tissues

Methods

Case report

Results

The authors describe a case of Noma in a 50‐year‐old female who developed a gangrenous oro‐facial lesion of her left face after cytotoxic chemotherapy for acute lymphoblastic leukemia. The patient was treated with broadspectrum intraveous antibiotics and extensive debridement of necrotic tissues followed by reconstruction of the large fullthickness defect.

Conclusion

Noma, or cancrum oris, is an uncommon ailment not well known in Europe or North America. Without treatment, the mortality rate of this dehumanizing infectious disease is 70%−90%. Early intervention and prevention of noma lesions in immunocompromised adults by optimizing their nutritional status, encouraging oral hygiene, maintaining adequate hydration, and closely monitoring intraoral lesions seems to be the key. Early lesions, such as acute necrotizing ulcerative gingivitis (ANUG), should be treated aggressively with oral hygiene, antibiotics (intravenous penicillin), and conservative debridement of necrotic tissues in addition to addressing the patient's hydration and nutritional status. If uncontrolled, Noma can destroy large amounts of both hard and soft tissues of the face which can present a formidable reconstructive challenge.
Endolymphatic Sac Decompression with and without Shunt for Vertigo and Hearing Sensitivity
Authors: Quinonez Rafael E , King Robert E , Marzo Sam J , Leonetti John P
Published: August 2004

Objectives

Endolymphatic sac decompression (ELSD) is a surgical alternative for those patients with Meniere's disease that are resistant to medical therapy. This safe, nondestructive surgical option can be performed with and without shunt placement. The present retrospective study investigates the long‐term efficacy of this surgical treatment with and without shunt placement.

Methods

Seventy‐five patients who underwent ELSD with or without shunts were included in the present investigation based on availability of pre‐ and postoperative data. Four‐tone average using. 5, 1, 2, and 3 kHz and speech discrimination scores were used to compare hearing pre‐ and postoperatively. Postoperative vertigo was rated as absent, decreased, unchanged, and increased when compared to preoperative vertigo. The preoperative data were obtained within 6 months prior to surgery and postoperative data within 6‐24 months following surgery.

Results

No improvement in hearing sensitivity was found postoperatively in either study group and no statistical difference was measured in hearing sensitivity between both groups. Vertigo was absent in 55%, decreased in 13%, unchanged in 15%, and increased in 17% of those patients not receiving a shunt. Vertigo in contrast was absent in 50%, decreased in 29%, unchanged in 14%, and increased in 7% of those patients with shunts.

Conclusion

These data suggest no benefit with regard to hearing. However, the data do suggest that postoperative vertigo in the shunt group is better controlled.
Otoacoustic Emissions in Patients with Tinnitus and Normal Hearing
Authors: Dall Igna Celso , Schmidt Leticia P , Smith Mariana , Facchini Luciana , Kang Suzie
Published: August 2004

Objectives

Tinnitus is defined as a sound perception in the absence of a sonorous external stimulus. This symptom is highly associated to hearing loss, although about 10% of the patients with tinnitus have a normal hearing. We studied the otoacoustic emissions (OE) in patients with complaints of tinnitus and normal hearing.

Methods

We evaluated 104 patients with tinnitus. Only 10 met the inclusion criterion that was to have thresholds of 20 dB or less in each frequency at tonal audiometry; 5 were men with average age of 36.1 years. OE was performed in each patient. History of occupational noise exposition was evaluated.

Results

Sixty percent had OE absent or lowered in one or more frequencies; 60% of them had a positive history of occupational noise exposition (time average of 7.58 years); and 83% of them did not use individual protection equipment.

Conclusion

One of the theories that try to explain the pathogenesis of tinnitus is the imbalance between external hairy cells (EHC) and internal hairy cells (IHC). The EHC are more prone to damage and, when it occurs, they fail to perform the inhibition over the ICH function. This lost of IHC inhibition results then in tinnitus. Our results agree with this theory mainly because our patients had alterations in the EHC demonstrated by the OE.
CO2 Laser for Lingual Tonsillectomy
Authors: Lomeo Paul E , McDonald John Edward , Finneman Judith L
Published: August 2004

Objectives

Hypertropic lingual tonsils are a known obstruction in the upper airway. Enlarged linguals are responsible for obstructive sleep apnea, potential infections, and difficult intubations for routine surgeries. In our institution all patients were treated with protection of the airway, and ablation of lingual tonsils with a CO2 laser.

Methods

The patients were diagnosed with direct visualization and a CT scan of the neck. All patients were intubated with a laser reinforced endotracheal tube and fire precautions were taken when draping patient. One patient had a tracheotmy performed before being treated for hypertrophic lingual tonsils. A wide funnell larynscope was suspended. The CO2 laser was used at 15 watts continuous along with an operating microscope to ablate the tissue.

Results

All patients were admitted for a 23‐hour stay. Postoperatively, no patient required intubation to protect the airway. Three of the 50 patients required a revision surgery to completely ablate all the lingual tonsils. The patient with the tracheotomy was decannulated. All patients were relieved and asymptomatic after surgery.

Conclusion

CO2 laser is a safe and acceptable method for lingual tonsillectomy. All patients in our institution had no complications and were free of all symptoms. The laser compleletly ablated the lingual tonsils removing the obstruction in the airway.
A neural‐specific splicing event generates an active form of the Wiskott‐Aldrich syndrome protein
Authors: Le Page Yann , Demay Florence , Salbert Gilles
Published: August 2004

Actin polymerization is required for cellular events such as podosome, lamellipode or filopode formation in migrating cells, and members of the Wiskott–Aldrich syndrome protein (WASP) family have essential roles in regulating actin dynamics at the cell leading edge. However, WASP proteins need first to be activated in order to be able to target actin polymerization. Here, we show the occurrence of a neural‐specific splicing event, which is favoured by the nuclear orphan receptor chicken ovalbumin upstream promoter–transcription factor I, and generates a truncated WASP protein deleted of exon 2‐encoded amino acids. This deletion relocates the protein to the plasma membrane and induces the formation of actin‐rich podosome‐like structures that also contain paxillin and vinculin. Furthermore, expression of the truncated protein in PC12 cells, as well as in primary neurons, stimulates neuritogenesis. These data underscore the importance of the neural‐specific splicing of WASP RNA during development.
Position of the CrPV IRES on the 40S subunit and factor dependence of IRES/80S ribosome assembly
Authors: Pestova Tatyana V , Lomakin Ivan B , Hellen Christopher U T
Published: August 2004

The cricket paralysis virus intergenic region internal ribosomal entry site (CrPV IGR IRES) can assemble translation initiation complexes by binding to 40S subunits without Met‐tRNAMeti and initiation factors (eIFs) and then by joining directly with 60S subunits, yielding elongation‐competent 80S ribosomes. Here, we report that eIF1, eIF1A and eIF3 do not significantly influence IRES/40S subunit binding but strongly inhibit subunit joining and the first elongation cycle. The IRES can avoid their inhibitory effect by its ability to bind directly to 80S ribosomes. The IRES's ability to bind to 40S subunits simultaneously with eIF1 allowed us to use directed hydroxyl radical cleavage to map its position relative to the known position of eIF1. A connecting loop in the IRES's pseudoknot (PK) III domain, part of PK II and the entire domain containing PK I are solvent‐exposed and occupy the E site and regions of the P site that are usually occupied by Met‐tRNAMeti.
A new spatiotemporally chaotic cryptosystem and its security and performance analyses
Authors: Lü Huaping , Wang Shihong , Li Xiaowen , Tang Guoning , Kuang Jinyu , Ye Weiping , Hu Gang
Published: August 2004

A one-way-coupled chaotic map lattice is proposed for cryptography of self-synchronizing stream cipher. The system performs basic floating-point analytical computation on real numbers, incorporating auxiliarily with few simple algebraic operations on integer numbers. Parallel encryption (decryption) operations of multiple chaotic sites are conducted. It is observed that the system has high practical security, fast encryption (decryption) speed with software realization, and excellent reliability against strong channel noise, and its overall cryptographic properties are considerably better than both known chaotic cryptosystems and currently used conventional cryptosystems, including the advanced encryption standard.
Experimental and theoretical investigation of the nonmodal growth of steady streaks in a flat plate boundary layer
Authors: Fransson Jens H. M. , Brandt Luca , Talamelli Alessandro , Cossu Carlo
Published: August 2004

An experimental and theoretical investigation aimed at describing the nonmodal growth of steady and spanwise periodic streamwise streaks in a flat plate boundary layer is presented. Stable laminar streaks are experimentally generated by means of a spanwise periodic array of small cylindrical roughness elements fixed on the plate. The streamwise evolution of the streaks is measured and it is proved that, except in a small region near the roughness elements, they obey the boundary layer scalings. The maximum achievable amplitude is mainly determined by the relative height of the roughness elements. Results are compared with numerical simulations of optimal and suboptimal boundary layer streaks. The theory is able to elucidate some of the discrepancies recently noticed between experimentally realizable nonmodal growth and optimal perturbation theory. The key factor is found to be the wall normal location and the extension of the laminar standing streamwise vortices inducing the streaks. The differences among previous experimental works can be explained by different dominating streak generation mechanisms which can be linked to the geometry and to the ratio between the roughness height and the boundary layer scale.
Ab initio theory of charge-carrier conduction in ultrapure organic crystals
Authors: Hannewald K. , Bobbert P. A.
Published: August 2004

We present an ab initio description of charge-carrier mobilities in organic molecular crystals of high purity. Our approach is based on Holstein’s original concept of small-polaron bands but generalized with respect to the inclusion of nonlocal electron–phonon coupling. By means of an explicit expression for the mobilities as a function of temperature in combination with ab initio calculations of the material parameters, we demonstrate the predictive power of our theory by applying it to naphthalene. The results show a good qualitative agreement with experiment and provide insight into the difference between electron and hole mobilities as well as their peculiar algebraic and anisotropic temperature dependencies.
Electroluminescence as a probe for elucidating electrical conductivity in a deoxyribonucleic acid-cetyltrimethylammonium lipid complex layer
Authors: Hirata Kunio , Oyamada Takahito , Imai Toshiro , Sasabe Hiroyuki , Adachi Chihaya , Koyama Tamami
Published: August 2004

We fabricated an organic light-emitting diode (OLED) using a DNA (deoxyribonucleic acid)-CTMA (cetyltrimethylammonium) lipid complex as an active charge transport layer to elucidate the semiconducting characteristics of the DNA-CTMA complex. From these OLED characteristics, we conclude that a DNA-CTMA layer preferentially transports holes rather than electrons. Furthermore, in using sandwiched device structures with the DNA-CTMA layer, we conclude that the DNA-CTMA layer basically possesses both hole and electron transport abilities and preferentially transports holes due to a shallow lowest unoccupied molecular orbital (LUMO) level that prohibits an efficient electron injection from an adjacent carrier transport layer.
Observation of fluorine-vacancy complexes in silicon
Authors: Simpson P. J. , Jenei Z. , Asoka-Kumar P. , Robison R. R. , Law M. E.
Published: August 2004

We show direct evidence, obtained by positron annihilation spectroscopy, for the complexing of fluorine with vacancies in silicon. Both float zone and Czochralski silicon wafers were implanted with 30keV fluorine ions to a fluence of 2×1014ions∕cm2, and studied in the as-implanted condition, and after annealing to 650°C for 10 and for 30min. The “2-detector” background reduction technique for positron annihilation was applied. The spectra reveal a significant concentration of fluorine-vacancy complexes after annealing, for both Czochralski and float zone material, supporting the results of computer simulations of the implantation and annealing process.
Compression of Zr2InC to 52GPa
Authors: Manoun Bouchaib , Saxena S. K. , Liermann H. P. , Gulve R. P. , Hoffman E. , Barsoum M. W. , Hug G. , Zha C. S.
Published: August 2004

Using a synchrotron-radiation source and a diamond-anvil cell, we measured the pressure dependence of the lattice parameters of a polycrystalline Zr2InC sample. Up to a pressure of 52GPa, no phase transformations were observed. As observed in Ti3SiC2 and Ti3Si0.5Ge0.5C2, the compressibility of Zr2InC along the c axis was greater than along the a axis. The bulk modulus is 127±5GPa, with a pressure derivative of 4.25±0.3; the former is in excellent agreement with our ab initio calculations (130.9GPa). The a(3.367Å) and c(15.100Å) parameters from the ab initio calculations are also slightly larger than those measured here, viz., 3.35 and 14.91Å. Surprisingly, a hysteresis was observed in the a-lattice parameters; they were higher upon unloading than loading. The reason for this hysteresis is not clear at this time.
In-plane dielectric properties of epitaxial 0.65Pb(Mg1∕3Nb2∕3)O3−0.35PbTiO3 thin films in a very wide frequency range
Authors: Wang Y. , Cheng Y. L. , Cheng K. C. , Chan H. L. W. , Choy C. L. , Liu Z. R.
Published: August 2004

The in-plane dielectric properties of epitaxial 0.65Pb(Mg1∕3Nb2∕3)O3−0.35PbTiO3 thin films deposited on MgO by pulsed-laser ablation were determined over a wide frequency range and compared with single crystals and ceramics. Depressed values of the dielectric constant, induced diffused phase transition, dielectric relaxation, and nonlinear behaviors were observed in the films. The overall dielectric behaviors of the films were found to be a mixture of that of relaxor ferroelectrics and normal ferroelectrics. The correlation of the microstructural features (mechanical clamping, small grain size, and epitaxial nature) and the dielectric behaviors was discussed.
Core-level photoemission spectroscopy of nitrogen bonding in GaNxAs1−x alloys
Authors: Veal T. D. , Mahboob I. , Piper L. F. J. , McConville C. F. , Hopkinson M.
Published: August 2004

The nitrogen bonding configurations in GaNxAs1−x alloys grown by molecular beam epitaxy with 0.07<x<0.11 have been studied using x-ray photoelectron spectroscopy (XPS). In contrast to previous studies of alloys with x⩾0.03, the nitrogen is found to exist in a single bonding configuration – the Ga–N bond; no interstitial nitrogen complexes are present. The amount of nitrogen in the alloys is estimated from the XPS using the N1s photoelectron and GaLMM Auger lines and is found to be in agreement with the composition determined by x-ray diffraction.
Near-infrared laser ablation of poly tetrafluoroethylene (Teflon) sensitized by nanoenergetic materials
Authors: Yang Yanqiang , Wang Shufeng , Sun Zhaoyong , Dlott Dana D.
Published: August 2004

Laser ablation of Teflon doped with size-selected (30–250nm) Al nanoparticles is studied. Unlike pure Teflon, which requires a vacuum-ultraviolet or femtosecond excimer laser for ablation, this sensitized Teflon can be ablated with a near-infrared laser. Using 100ps duration pulses, near-infrared ablation thresholds are lower by about a factor of 10 from excimer ablation of pure Teflon. A mechanism is discussed that involves Teflon decomposition by spherical shock fronts originating at each irradiated nanoparticle. Studies of the distance dependence of this process as a function of particle diameter and oxide layer thickness suggest ways of optimizing the ablation process.
Hydration kinetics of oriented lipid membranes investigated by energy dispersive x-ray diffraction
Authors: Caracciolo Giulio , Sadun Claudia , Caminiti Ruggero
Published: August 2004

Energy dispersive x-ray diffraction was applied to investigate the hydration kinetics of highly aligned 1,2-dioleoyl-3-trimethylammonium-propane membrane system. First, the adsorption of water into the lipid film results in a continous gain of interbilayer spatial coherence until a maximum is reached. Further, adsorbed water molecules behave as bulk water promoting loss of spatial coherence and leading to a progressive lowering and broadening of diffraction peaks. The possible molecular origin of this phenomenon is discussed.
Nanoscale deposition of solid inks via thermal dip pen nanolithography
Authors: Sheehan P. E. , Whitman L. J. , King William P. , Nelson Brent A.
Published: August 2004

We demonstrate that nanolithography can be performed using a heated atomic force microscope (AFM) cantilever tip to control the deposition of a solid organic “ink.” The ink, octadecylphosphonic acid (OPA), has a melting temperature near 100°C and can self-assemble on mica. Postdeposition analysis shows that deposition occurs only when the cantilever tip is heated above OPA’s melting temperature, that the deposited structure does not spread significantly while cooling, and that a cool tip coated with OPA does not contaminate the substrate during subsequent imaging. Single lines were written with a width of 100nm. This approach greatly expands the potential of dip pen nanolithography, allowing local control of deposition and deposition of materials typically immobile at room temperature, while avoiding potential problems arising from inadvertent deposition and postdeposition diffusion.
Area-selective formation of Si nanocrystals by assisted ion-beam irradiation during dual-ion-beam deposition
Authors: Kim Jae Kwon , Cha Kyu Man , Kang Jung Hyun , Kim Yong , Yi Jae-Yel , Chung Tae Hun , Bark Hong Jun
Published: August 2004

We investigate the effect of Ar-ion-beam irradiation during the deposition of SiOx films by dual-ion-beam deposition system. Ion-beam irradiation effectively increases the oxygen content, x, in SiOx films indicative of the preferential sputtering of Si phase as compared to SiO2 phase in SiOx films. We observe the intense photoluminescence from nonirradiated sample after postdeposition annealing at 1100°C indicating the formation of Si nanocrystals as shown by a cross-sectional transmission electron microscope. However, the increased oxygen content in ion-beam-irradiated sample results in small optical volume of small Si nanocrystals not sufficient for yielding appreciable photoluminescence intensity after postdeposition annealing. The property is utilized for achieving the area-selective formation of Si nanocrytals by inserting a shadow mask in assist ion beam during deposition.
Fabrication of a germanium quantum-dot single-electron transistor with large Coulomb-blockade oscillations at room temperature
Authors: Li P. W. , Liao W. M. , Kuo David M. T. , Lin S. W. , Chen P. S. , Lu S. C. , Tsai M.-J.
Published: August 2004

A simple and complementary metal-oxide-semiconductor-compatible method for fabricating germanium (Ge) single-electron transistors (SETs) is proposed, in which the Ge quantum dots (QDs) are naturally formed by selective oxidation of Si0.95Ge0.05∕Si wires on a silicon-on-insulator substrate. Clear Coulomb-blockade oscillations, Coulomb staircase, and negative differential conductances were experimentally observed at room temperature. The tunneling currents through the Ge QDs were simulated by the Anderson model with two energy levels. Analysis of the current–voltage characteristics indicates that the single-electron addition energy of the Ge QD is about 125meV.
Ostwald ripening and flattening of epitaxial ZnO layers during in situ annealing in metalorganic vapor phase epitaxy
Authors: Krost A. , Christen J. , Oleynik N. , Dadgar A. , Deiter S. , Bläsing J. , Krtschil A. , Forster D. , Bertram F. , Diez A.
Published: August 2004

ZnO films were grown at 450°C by metalorganic vapor phase epitaxy on GaN∕Si(111) substrate and subsequently annealed in situ at 900°C for times ranging from 0 to 8min. The epitaxial layers were characterized by atomic force microscopy, x-ray diffraction, and cathodoluminescence measurements. The as-grown ZnO layers consist of three-dimensional nanoscale-sized clusters of [0001]-oriented monocrystallites. During the first 1min of annealing, a surface smoothening due to a redistribution of material is observed leading to a decrease of both the island numbers and their heights. After 2min of annealing, the surface morphology has completely changed and is transformed into a nearly two-dimensional cluster-free surface. This phase transition is accompanied by a strong improvement of the crystalline and optical properties. The effect is attributed to Ostwald ripening with a subsequent flattening of the crystal surface.
Distribution of α and β phases in the coexistence regime in MnAs(0001) layers grown on GaAs(111)B
Authors: Takagaki Y. , Wiebicke E. , Däweritz L. , Ploog K. H.
Published: August 2004

The discontinuous change in the lattice constant that occurs at the first-order phase transition between α- and β-MnAs gives rise to a coexistence of the two phases in MnAs layers grown on GaAs substrates. When the GaAs substrates are oriented in the (111)B direction, the c axis of MnAs is aligned normal to the growth plane. We identify the domain structure of α- and β-MnAs for this crystal orientation by utilizing the different reactivities of the two phases against wet chemical etching. Submicrometer-size islands of α-MnAs are found to be interwoven in a honeycomblike network of β-MnAs. We also show that this domain structure combined with strain effects results in a formation of MnAs lumps by etching.
Effect of Ti thickness on contact resistance between GaN nanowiresand Ti∕Au electrodes
Authors: Hwang J. S. , Ahn D. , Hong S. H. , Kim H. K. , Hwang S. W. , Jeon B.-H. , Choi J.-H.
Published: August 2004

We demonstrate the effect of Ti thickness on the contact resistance between GaN nanowires and Ti∕Au electrodes. We have carried out systematic characterization of many GaN nanowires contacted by various Ti∕Au electrodes. We conclude that the average resistance is reduced by almost six orders of magnitude as Ti thickness increases from 0 to 20nm, and the resistance value then saturates when the Ti thickness further increases. Our observation can be explained by the formation of TiOx through the reaction of surface oxide and the Ti layer. Scanning Auger microscopy of the Au∕Ti∕SiO2 interface also supports this explanation.
Different origins of visible luminescence in ZnO nanostructures fabricated by the chemical and evaporation methods
Authors: Li D. , Leung Y. H. , Djurišić A. B. , Liu Z. T. , Xie M. H. , Shi S. L. , Xu S. J. , Chan W. K.
Published: August 2004

We prepared ZnO nanostructures using chemical and thermal evaporation methods. The properties of the fabricated nanostructures were studied using scanning electron microscopy, x-ray diffraction, photoluminescence, and electron paramagnetic resonance (EPR) spectroscopy. It was found that the luminescence in the visible region has different peak positions in samples prepared by chemical and evaporation methods. The samples fabricated by evaporation exhibited green luminescence due to surface centers, while the samples fabricated by chemical methods exhibited yellow luminescence which was not affected by the surface modification. No relationship was found between green emission and g∼1.96 EPR signal, while the sample with yellow emission exhibited strong EPR signal.
The effect of hydrogen etching on 6H-SiC studied by temperature-dependent current-voltage and atomic force microscopy
Authors: Doğan S. , Johnstone D. , Yun F. , Sabuktagin S. , Leach J. , Baski A. A. , Morkoç H. , Li G. , Ganguly B.
Published: August 2004

6 H – SiC was etched with hydrogen at temperatures between 1000 and 1450°C. The etched Si-terminated face for the 6H-SiC wafer was investigated by atomic force microscopy and temperature-dependent current–voltage (I–V–T) measurements. Mechanical polishing damage was effectively removed by hydrogen etching at temperatures above 1250°C. Atomic force microscopy images revealed that very good surface morphology, atomic layer flatness, and large and large step width were achieved. Schottky diode characteristics were investigated in detail by current–voltage and temperature-dependent current–voltage measurements, and the results showed a transition from defect assisted tunneling to thermionic emission as the annealing temperature was increased from 1250 to 1450°C.
Room-temperature ferromagnetism in chemically synthesized Sn1−xCoxO2 powders
Authors: Punnoose A. , Hays J. , Gopal V. , Shutthanandan V.
Published: August 2004

Room-temperature ferromagnetism is observed in chemically synthesized powder samples of Sn1−xCoxO2 with x=0.005 and 0.01. Magnetic hysteresis loops are observed at 300K with coercivity Hc∼630Oe, saturation magnetization Ms∼0.133μB∕Co ion, and about 31% remanence. Analyses of the magnetization data of paramagnetic samples with x=0.01 and 0.03, measured as a function of temperature (3–330K) and magnetic field (up to 65kOe), indicate the presence of Co+2 ions with spin S=3∕2. Magnetic data obtained from samples prepared at different temperatures indicate that the observed ferromagnetism for x⩽0.01 might have been triggered by changes in the oxygen stoichiometry.
Characterization of the field emission properties of individual thin carbon nanotubes
Authors: Jonge Niels de , Allioux Myriam , Doytcheva Maya , Kaiser Monja , Teo Kenneth B. K. , Lacerda Rodrigo G. , Milne William I.
Published: August 2004

Electron emission measurements were conducted on individual carbon nanotubes. The nanotubes had a closed end and their surfaces were thoroughly cleaned. It is shown conclusively that individual carbon nanotube electron emitters indeed exhibit Fowler–Nordheim behavior and have a work function of 5.1±0.1eV for the nanotubes under investigation, which had diameters of 1.4 and 4.9nm.
Efficient quantum key distribution with stable and expansible differential phase shift schemes
Authors: Chen Xiuliang , Zhou Chunyuan , Wu Guang , Zeng Heping
Published: August 2004

Efficient quantum key distribution can be achieved by using a stable differential phase shift scheme, with an expansible setup mainly composed of several parallel Mach–Zehnder interferometers, a serial Mach–Zehnder interferometer, and a Faraday mirror. An expansion of the scheme by adding more parallel Mach–Zehnder interferometers can conveniently increase the key creation efficiencies, and the energies of the interfering pulses can be equalized easily without changing the phase shifts in the serial interferometer. The long-term stabilities are guaranteed by using a multifeedback servo-system and Faraday mirror. And the sensibilities of the scheme to the disturbance of eavesdropping are improved by increasing the key creation efficiencies. The security of the scheme against some possible attacks, such as intercept/resend attack and Trojan horse attack, are discussed.
Extraordinary infrared transmission of Cu-coated arrays with subwavelength apertures: Hole size and the transition from surface plasmonto waveguide transmission
Authors: Williams Shaun M. , Stafford Amanda D. , Rogers Trisha M. , Bishop Sarah R. , Coe James V.
Published: August 2004

The zero-order, infrared transmission spectra were recorded and studied at varying angles of incidence to study the dispersion of the resonances in both the Γ−X and Γ−M reciprocal lattice directions. Reduction of hole size shows dramatic effects on the intensity of transmission, the width of the resonances, the identity of the most prominent resonances, and the dispersion behavior of resonances.