Investigations of carbon nanotubes epoxy composites for electronics packaging

The part of electronics packaging is steadily forced to adapt the requirements of the microelectronic industry. For future electronics application such needs will be: 1) steady miniaturisation of the electronic devices 2) high pin count up to 5000 i / o per device 3) pitches down to 20 mum 4) higher current density per devices 5) higher thermal dissipation loss This is only a small extract of the challenges facing the electronics packaging industry in the future. The aim and duty for electronics packaging is to realize a reliable package for future electronics. Commonplace materials for joining elements like solder are not able to solve these requirements. For example in [1] the authors describe that future IC's operating at high frequencies of 10-28 GHz, signal bandwidths of 20 Gbps and lower supply voltages require an estimated maximum of R (< 10 mOhm), L (<5-10pH) and C (<5-10 fF).[l] Current joining elements can not meet these requirements. To solve these problems the electronics packaging industry researches technologies and materials of the nanotechnology. Especially researches concerning new materials for electronics packaging rise up since the last three years. One of the most researched new materials are Carbon Nanotubes (CNT). Carbon Nanotubes have superior mechanical, electrical and thermal properties. Due to these properties CNT are considered as promising candidates in packaging technology. The most interesting field of application is the use of the Carbon Nanotubes as filler in electrical conductive adhesives. The aim is to improve the performance of conductive adhesives in comparison to common products. This study deals with characterization of carbon nanotube / epoxy adhesives in electronics packaging. For this study we optimize the CNT - adhesive system by modification of the CNT, use of different dispersion technologies and under variation of the epoxy matrix. The resulting adhesives are characterized by measuring their viscosity, mech- anical strength and their thermal and electrical conductivity. For all studies Multi Wall Nanotubes were used which can be purchased at a reasonable price. For modification of the CNT they can be treated by low pressure plasma (cvd), UV / ozone treatment or modifiedchemically in solution to achieve a higher polarity resulting in a better dispersibility. Also bonding to the polymer matrix is improved. Success of the processes is studied by XPS and REM. For dispersion technology ultrasonic bath, speed mixing and/or treatment with a roll calander can be used. The polymer matrix is also varied in order to achieve an appropriate viscosity at the CNT-content of interest that enables good results in screen printing. Also CNT-polymer interaction can be adapted by varying polarity of the resin used. The distribution of CNT in the matrix is studied by TEM. The first investigations show that ultrasonic finger is the favourable dispersion technology to achieve well dispersed CNT. For modification of the CNT the plasma treatment came out to be efficient to give appropriate amounts of hydroxyl groups

Effect of endodontic treatment on periodontal healing of grade 3 endo-periodontal lesions without root damage in periodontally compromised patients—a retrospective pilot study

Objectives!#!There is little evidence about the effect of different treatment protocols for grade 3 endo-periodontal lesions without root damage in patients with periodontitis according to the new classification of periodontal disease. The aim of this study is to evaluate the impact of endodontic treatment on the achievement of periodontal healing.!##!Materials and methods!#!Teeth with the initial diagnosis endo-periodontal lesion without root damage grade 3, treated with a standardized endodontic treatment protocol, were included in this study. A retrospective analysis was performed to assess the impact on periodontal healing by evaluating probing pocket depth (PPD), clinical attachment gain (CAL), and periapical index score (PAI).!##!Results!#!Nineteen teeth and 13 patients were included. A mean reduction of 3.19 ± 3.41 mm in PPD was recorded. The mean CAL gain was 2.33± 3.75 mm. Five teeth (45.4%) showed an improvement of PAI and were classified as treatment success.!##!Conclusions!#!The results failed to show a highly predictable treatment outcome for endo-periodontal lesion grade 3 without root damage in patients with periodontitis. However, endodontic therapy alone resulted in treatment success for some of the teeth, which would otherwise have had a poor prognosis.!##!Clinical relevance!#!Endo-periodontal lesions can often be challenging for dentists in daily clinical practice. To date, there is not much evidence for practitioners to rely on. Therefore, this study aims to strengthen the evidence for the management and treatment of endo-periodontal lesions. Although the outcome is not highly predictable yet, teeth with the initial diagnosis endo-periodontal lesion without root damage grade 3 can benefit from an endodontic treatment

Ex vivo assessment of the buccal and oral bone by CBCT

Purpose!#!Identifying buccal and oral bone as an important supporting periodontal structure for teeth provides important information for treatment planning in periodontics and orthodontics. This study aims to add evidence to the knowledge of preciseness of cone beam computed tomography (CBCT) measurements of the vertical dimension of buccal and oral bone. The hypothesis is that CBCT is an accurate and reliable method to measure vertical vestibular and oral bone loss.!##!Methods!#!The amount of vertical buccal and oral bone loss (bl) of 260 sites of 10 human cadavers was investigated clinically and radiographically by CBCT. Radiographic measurements were rated by two blinded raters. Measurements and the corresponding differences between clinical and radiological findings are described by medians and quartiles (Q1-Q3). For statistical analysis, Lin's concordance correlation coefficient (CCC) and Bland-Altman plots were calculated.!##!Results!#!The CCC between the raters was 0.994 (95% confidence interval 0.992-0.995). The median bone loss (bl) distance from the cementoenamel junction (CEJ) to the bony defect (BD) was 3.5 mm (range 3-5 mm). The median bl measured in the CBCT was 3.8 mm (range 3.1-4.8 mm). The median difference of the 2 measurements for all sites included in the study (N = 260) was -0.2 mm (-0.7 to 0.3 mm).!##!Conclusions!#!CBCT seems to be an accurate and highly reliable method to detect and describe vertical buccal and oral bone loss. It could improve planning and prediction for successful combined periodontal and orthodontic therapies

MR neurography in ulnar neuropathy as surrogate parameter for the presence of disseminated neuropathy.

PURPOSE: Patients with ulnar neuropathy of unclear etiology occasionally present with lesion extension from elbow to upper arm level on MRI. This study investigated whether MRI thereby distinguishes multifocal neuropathy from focal-compressive neuropathy at the elbow. METHODS: This prospective study was approved by the institutional ethics committee and written informed consent was obtained from all participants. 122 patients with ulnar mononeuropathy of undetermined localization and etiology by clinical and electrophysiological examination were assessed by MRI at upper arm and elbow level using T2-weighted fat-saturated sequences at 3T. Twenty-one patients were identified with proximal ulnar nerve lesions and evaluated for findings suggestive of disseminated neuropathy (i) subclinical lesions in other nerves, (ii) unfavorable outcome after previous decompressive elbow surgery, and (iii) subsequent diagnosis of inflammatory or other disseminated neuropathy. Two groups served as controls for quantitative analysis of nerve-to-muscle signal intensity ratios: 20 subjects with typical focal ulnar neuropathy at the elbow and 20 healthy subjects. RESULTS: In the group of 21 patients with proximal ulnar nerve lesion extension, T2-w ulnar nerve signal was significantly (p<0.001) higher at upper arm level than in both control groups. A cut-off value of 1.92 for maximum nerve-to-muscle signal intensity ratio was found to be sensitive (86%) and specific (100%) to discriminate this group. Ten patients (48%) exhibited additional T2-w lesions in the median and/or radial nerve. Another ten (48%) had previously undergone elbow surgery without satisfying outcome. Clinical follow-up was available in 15 (71%) and revealed definitive diagnoses of multifocal neuropathy of various etiologies in four patients. In another eight, diagnoses could not yet be considered definitive but were consistent with multifocal neuropathy. CONCLUSION: Proximal ulnar nerve T2 lesions at upper arm level are detected by MRI and indicate the presence of a non-focal disseminated neuropathy instead of a focal compressive neuropathy

The impact of splinting timepoint of mobile mandibular incisors on the outcome of periodontal treatment—preliminary observations from a randomized clinical trial

Objectives!#!To compare the outcome of periodontal parameters in mobile mandibular incisors which were splinted before or after full-mouth disinfection (FMD).!##!Materials and methods!#!Thirty-four periodontitis patients with ≥ 1 mobile mandibular incisor (mobility degree II/III, clinical attachment loss (CAL) ≥ 5 mm, relative bone loss ≥ 50%) were randomly allocated to group A or B. Patients received periodontal treatment (PT) including splinting of teeth 33-43 before (A) or after FMD (B). Patient (age/sex/smoking status/systemic diseases/number of teeth) and tooth-related parameters (mean probing pocket depth (PPD)/CAL/oral hygiene indices; for the overall dentition and region 33-43) were assessed prior to PT and 12 months after FMD by a blinded examiner. Therapy-related information was added (group/antibiotic therapy/surgical intervention).!##!Results!#!Twenty-six patients (A: 12; B:14) were re-examined. Two patients of group B did not need splinting after FMD because of reduction in mobility after FMD. Regression analysis revealed a positive association of antibiotic therapy with CAL_overall, PPD_overall, and PPD_33-43 (p ≤ 0.01). There is a trend toward a higher reduction of periodontal parameters at teeth 33-43 in group A (PPD_33-43: - 0.91 vs. - 0.27 mm; CAL_33-43: - 1.02 vs. - 0.47 mm).!##!Conclusions!#!Teeth splinted before or after FMD show a significant improvement in periodontal parameters 12 months after FMD. Splinting after FMD offered the option to detect reduction in mobility.!##!Clinical relevance!#!Despite a higher, but not statistically significant, improvement in periodontal parameters on teeth splinted before FMD, the results do not indicate which timepoint of splinting is more beneficial. The decision for the therapeutic procedure should therefore be made individually

DTI parameter values of the median nerve at the wrist from proximal to distal.

<p>X-axis denotes the distance from the reference structure (hamulus of the hamate bone) in millimeters. Negative/positive values indicate position proximal/distal to that reference, respectively. Errorbars denote the standard error of the mean. FA: fractional anisotropy; AD: axial diffusivity; MD: mean diffusivity; RD: radial diffusivity.</p