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1.
ESMO Open ; 9(7): 103623, 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38959698

ABSTRACT

BACKGROUND: Uveal melanoma (UM) is a rare malignancy where 50% of patients develop metastatic disease primarily affecting the liver. Approximately 40% of patients with metastatic UM respond to one-time isolated hepatic perfusion (IHP) with high-dose melphalan. This phase I trial investigates the safety and clinical efficacy of IHP combined with ipilimumab (IPI) and nivolumab (NIVO). PATIENTS AND METHODS: Immunotherapy-naïve patients were randomized in this phase I trial to receive either IHP followed by IPI 3 mg/kg and NIVO 1 mg/kg (IPI3/NIVO1) for four cycles (post-operative arm), or one cycle of preoperative IPI3/NIVO1, IHP and then three cycles of IPI3/NIVO1 (pre-post-operative arm), followed by maintenance therapy with NIVO 480 mg for 1 year. RESULTS: Eighteen patients were enrolled and randomized. Three patients did not undergo IHP as planned. In total, 11/18 patients (6 in the post-operative arm and 5 in the pre-post-operative arm) did not complete the planned four cycles of IPI3/NIVO1. Toxicity to IHP was similar in both groups, but the number of immune-related adverse events (AEs) was higher in the pre-post-operative arm. Among assessable patients, overall response rate was 57% in the post-operative arm (4/7) and 22% in the pre-post-operative arm (2/9). CONCLUSIONS: Combination therapy with IHP and IPI3/NIVO1 was associated with severe AEs. The efficacy of this combination is encouraging with high response rates. One cycle of preoperative IPI/NIVO before IHP did not show potential benefits in terms of safety or efficacy.

2.
Rev Sci Instrum ; 92(3): 035002, 2021 Mar 01.
Article in English | MEDLINE | ID: mdl-33820055

ABSTRACT

The advances in the fields of scanning probe microscopy, scanning tunneling spectroscopy, point contact spectroscopy, and point contact Andreev reflection spectroscopy to study the properties of conventional and quantum materials under cryogenic conditions have prompted the development of nanopositioners and nanoscanners with enhanced spatial resolution. Piezoelectric-actuator stacks as nanopositioners with working strokes of 10 µm and positioning resolution ∼(1-10) nm are desirable for both basic research and industrial applications. However, information on the performance of most commercial piezoelectric actuators in cryogenic environment and in the presence of magnetic fields in excess of 5 T is generally not available. In particular, the magnitude, the rate, and the associated hysteresis of the piezo-displacement at cryogenic temperatures are the most relevant parameters that determine whether a particular piezoelectric actuator can be used as a nanopositioner. Here, the design and realization of an experimental setup based on interferometric techniques to characterize a commercial piezoelectric actuator over a temperature range of 2 K ≤ T ≤ 260 K and magnetic fields up to 6 T are presented. The studied piezoelectric actuator has a maximum displacement of 30 µm at room temperature for a maximum driving voltage of 75 V, which reduces to 1.2 µm with an absolute hysteresis of 9.1±3.3nm at T = 2 K. The magnetic field is shown to have no substantial effect on the piezo-properties of the studied piezoelectric-actuator stack.

3.
Scand J Gastroenterol ; 54(6): 746-752, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31190577

ABSTRACT

Background: Sweden has traditionally been considered a country with a low incidence of hepatocellular carcinoma (HCC). However, the increasing number of immigrants from areas with a high incidence of HCC might affect the number of HCC patients in Sweden. Aim: To examine trends in the incidence, treatment and overall survival of patients with HCC and an underlying liver disease (ULD) from a restricted, well-defined region of Sweden, between 2000 and 2014. Patients and methods: Nine hundred and eight patients with HCC were identified. Subjects were grouped into 5-year periods, and analysed for HCC diagnosis, ULD, staging and treatment selection in populations born outside Sweden versus non-immigrants and patient survival. The regions were Africa, Asia, EU-28 together with America and the Nordic countries, eastern Europe and Sweden. Results: Over the time periods, the patients with HCC and ULD increased. More patients from Africa had HCC and ULD than what would have been expected based on the number of immigrants from this region and they were also significantly younger than Sweden-born patients. For patients from Africa, Asia and eastern Europe; viral hepatitis was dominating ULDs. Patients from Africa, Asia and eastern Europe were subjected to liver transplantation (LT) in higher proportions than patients from Sweden. The survival rate for patients from eastern Europe was significantly better. Conclusions: Immigration increased the incidence of HCC and the need for active treatment such as LT. This fact raises the question of whether immigrants from regions with a high incidence of HCC ought to be subjected to mandatory hepatitis B and C virus (HBV and HCV) diagnosis and consequent liver ultrasounds for diagnosis of occult HCC. With such strategies, the morbidity and mortality of HCC could be reduced.


Subject(s)
Carcinoma, Hepatocellular/ethnology , Emigrants and Immigrants , Liver Neoplasms/ethnology , Adolescent , Adult , Africa/ethnology , Aged , Aged, 80 and over , Asia/ethnology , Carcinoma, Hepatocellular/mortality , Carcinoma, Hepatocellular/therapy , Child , Child, Preschool , Europe, Eastern/ethnology , Female , Hepatitis B, Chronic/ethnology , Hepatitis C, Chronic/ethnology , Humans , Incidence , Infant , Infant, Newborn , Liver Neoplasms/mortality , Liver Neoplasms/therapy , Liver Transplantation , Male , Middle Aged , Proportional Hazards Models , Risk Factors , Scandinavian and Nordic Countries/ethnology , Survival Rate , Sweden/epidemiology , Ultrasonography , Young Adult
4.
J Biotechnol ; 296: 53-60, 2019 Apr 20.
Article in English | MEDLINE | ID: mdl-30898686

ABSTRACT

Microbial contamination in mammalian cell cultures causing rejected batches is costly and highly unwanted. Most methods for detecting a contamination are time-consuming and require extensive off-line sampling. To circumvent these efforts and provide a more convenient alternative, we used an online in situ microscope to estimate the cell diameter of the cellular species in the culture to distinguish mammalian cells from microbial cells depending on their size. A warning system was set up to alert the operator if microbial cells were present in the culture. Hybridoma cells were cultured and infected with either Candida utilis or Pichia stipitis as contaminant. The warning system could successfully detect the introduced contamination and alert the operator. The results suggest that in situ microscopy could be used as an efficient online tool for early detection of contaminations in cell cultures.


Subject(s)
Cell Culture Techniques/methods , Hybridomas/microbiology , Microscopy/methods , Animals , Candida/isolation & purification , Candida/pathogenicity , Culture Media/analysis , Humans , Hybridomas/cytology , Pichia/isolation & purification , Pichia/pathogenicity
5.
Rev Sci Instrum ; 90(12): 123705, 2019 Dec 01.
Article in English | MEDLINE | ID: mdl-31893779

ABSTRACT

A scanning tunneling microscope for spin-resolved studies of dynamic systems is presented. The cryogenic setup allows the scanning tunneling microscope to achieve a cutoff frequency beyond 26 GHz at the tunnel junction and to be operable at temperatures of 1.1 K-100 K in a magnetic field of up to 3 T. For this purpose, the microscope and its wiring as well as the associated cryostat system were specially designed and manufactured. For sample preparation, an ultrahigh vacuum system was developed, which is equipped with modular preparation platforms. Measurements showing the characteristics of the scanning tunneling microscope in the time and frequency domain are presented. As a proof of concept, experimental data of the Pd/Fe/Ir(111) sample system at 95 K in a magnetic field of 3 T are presented.

6.
J Biotechnol ; 259: 83-85, 2017 Oct 10.
Article in English | MEDLINE | ID: mdl-28780163

ABSTRACT

In situ Microscopy (ISM) is an optical non-invasive technique to monitor cells in bioprocesses in real-time. Escherichia coli is the most studied and used organism in biotechnology. In this article the cell density in Escherichia coli cultivations was monitored by applying ISM in these cultivations. The acquired images were analyzed with an image processing algorithm to determine the turbidity of the cultivation medium. In three cultivations the cell density was monitored with the algorithm and offline samples were taken to determine the dry cell mass (DCM). Both results were correlated and concentrations up to 70g/L DCM could be measured via ISM. For higher cell densities a saturation was recognized. The deviation of the calibration lines within three cultivations was 8%.


Subject(s)
Bioreactors/microbiology , Cell Count/methods , Escherichia coli/cytology , Image Processing, Computer-Assisted/methods , Microscopy/methods , Algorithms , Escherichia coli/growth & development
7.
BMC Oral Health ; 17(1): 32, 2016 Aug 02.
Article in English | MEDLINE | ID: mdl-27485732

ABSTRACT

BACKGROUND: The aim of this study was to determine the success of psychotherapeutic treatment for dental phobia by measurement of anxiety using the dental anxiety score (DAS), the state trait anxiety score (STAI state), salivary cortisol and protein concentrations and the salivary secretion rate. Primary endpoint of the study was the comparison of the data before and after psychotherapeutic treatment. METHODS: Forty patients were included into the study. Twenty-four were allocated to the phobic group, 16 to the control group. Saliva was collected upon entering the dental clinic and again after three weeks of psychotherapy. The results were compared with those of a control group. The DAS and STAI questionnaires were completed at each visit. RESULTS: A reduction in DAS values was found after psychotherapy. However, the values remained significantly higher in the phobic group than in the controls. Similar results were found for STAI scores. A slightly higher salivary cortisol level was found in the phobic group. No changes occurred in cortisol or protein concentrations. The salivary secretion rate increased in the phobic patients after psychotherapy. CONCLUSIONS: It could be concluded that psychotherapy is effective in the treatment of dental phobic patients. TRIAL REGISTRATION: This study has been retrospectively registered in the German Clinical Trials Register (# DRKS00009552 ) on 10/19/15.


Subject(s)
Dental Anxiety/therapy , Psychotherapy , Anxiety , Humans , Hydrocortisone/analysis , Saliva/chemistry , Surveys and Questionnaires
8.
J Biotechnol ; 234: 90-98, 2016 Sep 20.
Article in English | MEDLINE | ID: mdl-27485811

ABSTRACT

In situ Microscopy (ISM) is an optical non-invasive technique to monitor cells in bioprocesses in real-time. Pichia pastoris is one of the most promising protein expression systems. This yeast combines fast growth on simple media and important eukaryotic features such as glycosylation. In this work, the ISM technology was applied to Pichia pastoris cultivations for online monitoring of the cell concentration during cultivation. Different ISM settings were tested. The acquired images were analyzed with two image processing algorithms. In seven cultivations the cell concentration was monitored by the applied algorithms and offline samples were taken to determine optical density (OD) and dry cell mass (DCM). Cell concentrations up to 74g/L dry cell mass could be analyzed via the ISM. Depending on the algorithm and the ISM settings, an accuracy between 0.3 % and 12 % was achieved. The overall results show that for a robust measurement a combination of the two described algorithms is required.


Subject(s)
Cell Culture Techniques , Microscopy/methods , Pichia/growth & development , Algorithms , Biomass , Bioreactors , Image Processing, Computer-Assisted , Microscopy/instrumentation , Pichia/cytology , Pichia/metabolism
9.
J Phys Chem B ; 120(24): 5505-12, 2016 06 23.
Article in English | MEDLINE | ID: mdl-27231751

ABSTRACT

The structure of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)-stabilized colloidal tetracosane emulsions was investigated by photon correlation spectroscopy and small-angle X-ray and neutron scattering, using emulsions with different neutron scattering contrasts. Special emphasis was placed on the structure of the DMPC stabilizer layer covering the emulsion droplets. A monolayer, structurally similar to a half DMPC bilayer, with a thickness of 16 Å is found. Thereby, the phosphocholine headgroups arrange flat at the oil-water interface. A deep penetration of the tetracosane oil into the stabilizer layer can be ruled out.

10.
J Phys Chem B ; 120(24): 5513-26, 2016 06 23.
Article in English | MEDLINE | ID: mdl-27232983

ABSTRACT

Using photon correlation spectroscopy, transmission electron microscopy, microcalorimetry, wide-angle X-ray scattering (WAXS), and small-angle X-ray and neutron scattering (SAXS, SANS), the structure of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)-stabilized colloidal tetracosane suspensions was studied from the molecular level to the microscopic scale as a function of the temperature. The platelike nanocrystals exhibit for tetracosane an unusual orthorhombic low-temperature crystal structure. The corresponding WAXS pattern can be reproduced with a predicted orthorhombic unit cell (space group Pca21), which usually occurs only for much longer even-numbered n-alkanes. Special emphasis was placed on the structure of the DMPC stabilizer layer covering the nanocrystals. Their structure was investigated by SAXS and SANS, using suspensions with different neutron scattering contrasts. As for the emulsions in Part I , the crystallized nanoparticles are covered by a DMPC monolayer. Their significant smaller thickness of 10.5 Å (for the emulsions in Part I : 16 Å) could be related to a more tilted orientation of the DMPC molecules to cover the expanded surface of the crystallized nanoparticles.

11.
Transl Psychiatry ; 6: e714, 2016 Jan 19.
Article in English | MEDLINE | ID: mdl-26784968

ABSTRACT

The behavioral phenotype and genotype of conduct disorder (CD) differ in males and females. Abnormalities of white matter integrity have been reported among males with CD and antisocial personality disorder (ASPD). Little is known about white matter integrity in females with CD. The present study aimed to determine whether abnormalities of white matter are present among young women who presented CD before the age of 15, and whether abnormalities are independent of the multiple comorbid disorders and experiences of maltreatment characterizing females with CD that may each in themselves be associated with alterations of the white matter. Three groups of women, aged on average 24 years, were scanned using diffusion tensor imaging and compared: 28 with prior CD, three of whom presented ASPD; a clinical comparison (CC) group of 15 women with no history of CD but with similar proportions who presented alcohol dependence, drug dependence, anxiety disorders, depression disorders and physical and sexual abuse as the CD group; and 24 healthy women. Whole-brain, tract-based spatial statistics were computed to investigate differences in fractional anisotropy, axial diffusivity and radial diffusivity. Compared with healthy women, women with prior CD showed widespread reductions in axial diffusivity primarily in frontotemporal regions. After statistically adjusting for comorbid disorders and maltreatment, group differences in the corpus callosum body and genu (including forceps minor) remained significant. Compared with the CC group, women with CD showed reduced fractional anisotropy in the body and genu of the corpus callosum. No differences were detected between the CD and healthy women in the uncinate fasciculus.


Subject(s)
Conduct Disorder/pathology , Corpus Callosum/pathology , Violence , Adult , Comorbidity , Conduct Disorder/epidemiology , Diffusion Tensor Imaging , Female , Humans , Magnetic Resonance Imaging , Mental Disorders/epidemiology , Mental Disorders/pathology , Young Adult
12.
Phys Chem Chem Phys ; 17(8): 6122-34, 2015 Feb 28.
Article in English | MEDLINE | ID: mdl-25644750

ABSTRACT

Microemulsions with supercritical CO2 are promising alternatives for organic solvents, especially if both polar and non-polar components need to be dissolved. However, only fluorinated surfactants, which are known to be environmentally unfriendly, are appropriate to formulate well-structured microemulsions. While most approaches to increase the environmental performance of CO2-microemulsions deal with the design of new surfactants with a reduced degree of fluorination, we discovered that the partial substitution of CO2 by cyclohexane enables a considerable reduction of fluorinated surfactants. Thereby, the most efficient solubilization of the CO2/cyclohexane mixture, which turned out to be pressure-dependent, was found at a cyclohexane-to-CO2 mass ratio between 1 : 6 and 1 : 4. In order to elucidate this unexpected effect a systematic Small Angle Neutron Scattering (SANS) contrast variation study was performed. The analysis of the recorded scattering curves by the Generalized Indirect Fourier Transformation (GIFT) clearly shows that the scattering length density profiles differ considerably from CO2-microemulsions without cyclohexane. Instead of a nearly constant scattering length density, a density profile that varies systematically over half of the droplet radius was detected. These results clearly indicate that the observed efficiency boosting is caused by the formation of a depletion zone of cyclohexane close to the fluorinated amphiphilic film.

13.
Ann Surg Oncol ; 21(2): 466-72, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24141377

ABSTRACT

BACKGROUND: Uveal melanoma is the most common primary intraocular malignancy in adults. Despite successful control of the primary tumor, metastatic disease will ultimately develop in approximately 35% of the patients, with the liver being the most common site for metastases. These metastases are generally refractory to systemic chemotherapy, and the median survival for patients with liver metastases is about 6 months. This phase II trial reports the experience of isolated hepatic perfusion (IHP) as a treatment option. METHOD: A total of 34 patients with isolated liver metastasis from ocular melanoma underwent IHP. An overall survival comparison was made using data retrieved from the National Patient Register managed by the Swedish National Board of Health and Welfare. RESULTS: An overall radiological response was seen in 68% of the patients, with 12% having a complete response. Time to local progression was 7 months; 68% of the patients developed extrahepatic metastases after a median of 13 months, and the median overall survival was 24 months. There was a significant survival advantage of 14 months (p = 0.029) when comparing these patients with a control group consisting of the longest surviving patients in Sweden with uveal melanoma liver metastases not treated with IHP. CONCLUSIONS: IHP is a treatment option with a high response rate and a potential survival benefit of more than 1 year. IHP should be considered an option in the treatment of uveal melanoma metastases. A randomized trial comparing IHP and best alternative care will start during 2013 (the SCANDIUM trial, ClinicalTrials.gov identifier NCT01785316).


Subject(s)
Chemotherapy, Cancer, Regional Perfusion , Eye Neoplasms/mortality , Liver Neoplasms/mortality , Melanoma/mortality , Melphalan/therapeutic use , Perfusion , Postoperative Complications/mortality , Adolescent , Adult , Aged , Antineoplastic Agents, Alkylating/therapeutic use , Combined Modality Therapy , Disease Progression , Eye Neoplasms/pathology , Eye Neoplasms/therapy , Female , Follow-Up Studies , Humans , Liver Neoplasms/secondary , Liver Neoplasms/therapy , Male , Melanoma/pathology , Melanoma/therapy , Middle Aged , Neoplasm Staging , Prognosis , Registries , Survival Rate , Sweden , Young Adult
14.
Phys Rev Lett ; 110(19): 196002, 2013 May 10.
Article in English | MEDLINE | ID: mdl-23705721

ABSTRACT

We present a one-to-one comparison of polymer segmental fluctuations as measured by small angle neutron scattering in a network under deformation with those obtained by neutron spin echo spectroscopy. This allows an independent proof of the strain dependence of the chain entanglement length. The experimentally observed nonaffine square-root dependence of the tube channel on strain is in excellent agreement with theoretical predictions and permits us to exclude an often invoked nondeformed as well as affinely deformed tube.

15.
J Chem Phys ; 137(20): 204909, 2012 Nov 28.
Article in English | MEDLINE | ID: mdl-23206033

ABSTRACT

Binary mixtures of colloidal particles of sufficiently different sizes or shapes tend to demix at high concentration. Already at low concentration, excluded volume interactions between the two species give rise to structuring effects. Here, a new theoretical description is proposed of the structure of colloidal sphere-plate mixtures, based on a density expansion of the work needed to insert a pair of spheres and a single sphere in a sea of them, in the presence or not of plates. The theory is first validated using computer simulations. The predictions are then compared to experimental observations using silica spheres and gibbsite platelets. Small-angle neutron scattering was used to determine the change of the structure factor of spheres on addition of platelets, under solvent contrast conditions where the platelets were invisible. Theory and experiment agreed very well for a platelet/sphere diameter ratio D∕d = 2.2 and reasonably well for D∕d = 5. The sphere structure factor increases at low scattering vector Q in the presence of platelets; a weak reduction of the sphere structure factor was predicted at larger Q, and for the system with D∕d = 2.2 was indeed observed experimentally. At fixed particle volume fraction, an increase in diameter ratio leads to a large change in structure factor. Systems with a larger diameter ratio also phase separate at lower concentrations.

16.
Sci Rep ; 2: 305, 2012.
Article in English | MEDLINE | ID: mdl-22396852

ABSTRACT

In the present study we quantify stress by measuring transient perspiratory responses on the perinasal area through thermal imaging. These responses prove to be sympathetically driven and hence, a likely indicator of stress processes in the brain. Armed with the unobtrusive measurement methodology we developed, we were able to monitor stress responses in the context of surgical training, the quintessence of human dexterity. We show that in dexterous tasking under critical conditions, novices attempt to perform a task's step equally fast with experienced individuals. We further show that while fast behavior in experienced individuals is afforded by skill, fast behavior in novices is likely instigated by high stress levels, at the expense of accuracy. Humans avoid adjusting speed to skill and rather grow their skill to a predetermined speed level, likely defined by neurophysiological latency.


Subject(s)
Hand/physiology , Stress, Physiological , Task Performance and Analysis , Humans
17.
Ann Surg Oncol ; 19(6): 1800-7, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22219068

ABSTRACT

BACKGROUND: Isolated limb perfusion with tumor necrosis factor alpha and melphalan (TM-ILP) has proven to be a successful option in treating advanced soft tissue sarcomas (STS), where amputation otherwise is needed to achieve safe surgical margins. METHODS: From 2000 to 2009, 54 patients with locally advanced STS, who all were candidates for amputation, were treated with totally 57 TM-ILP procedures and then followed prospectively. The median follow-up time was 30 months. Median tumor size was 10 cm, and 94% of the patients had high-grade tumors. RESULTS: The clinical overall response after TM-ILP was 71% (including 21% CR), and 60% of the patients underwent resection of the tumor remnant after a median of 2 months. The histopathologic response rate in the resected specimens was 76%. Local recurrence/progress occurred in 37% of the patients after a median of 7 months. Thirteen patients finally underwent amputation after a median of 11 months, giving a long-term limb salvage of 76%. CONCLUSIONS: TM-ILP of advanced soft tissue sarcoma of the extremities makes limb-sparing surgery possible in a high proportion of patients.


Subject(s)
Chemotherapy, Cancer, Regional Perfusion , Extremities/pathology , Limb Salvage , Melphalan/therapeutic use , Neoplasm Recurrence, Local/therapy , Sarcoma/therapy , Tumor Necrosis Factor-alpha/therapeutic use , Adolescent , Adult , Aged , Aged, 80 and over , Amputation, Surgical , Antineoplastic Agents, Alkylating/therapeutic use , Extracorporeal Circulation , Extremities/surgery , Female , Follow-Up Studies , Humans , Male , Middle Aged , Neoplasm Grading , Neoplasm Recurrence, Local/pathology , Neoplasm Staging , Prospective Studies , Sarcoma/pathology , Survival Rate , Time Factors , Treatment Outcome , Young Adult
18.
Phys Rev Lett ; 106(22): 228301, 2011 Jun 03.
Article in English | MEDLINE | ID: mdl-21702636

ABSTRACT

Binary mixtures of ultrasoft colloids and linear polymer chains were investigated by small-angle neutron scattering and liquid state theory. We show that experimental data can be described by employing recently developed effective interactions between the colloid and the polymer chains, in which both components are modeled as point particles in a coarse-grained approach, in which the monomers have been traced out. Quantitative, parameter-free agreement between experiment and theory for the pair correlations, the phase behavior and the concentration dependence of the interaction length is achieved.

19.
Adv Colloid Interface Sci ; 163(1): 53-83, 2011 Mar 15.
Article in English | MEDLINE | ID: mdl-21367392

ABSTRACT

Analytical expressions for the scattering patterns of ordered nano- and mesoscopic materials are derived and compared to measured scattering patterns. Ordered structures comprising spheres (fcc, bcc, hcp, sc, and bct), cylinders (hex and sq), lamellae (lam) and vesicles, as well as bicontinuous cubic structures (Ia3d, Pn3m, and Im3m) are considered. The expressions take into account unit cell dimensions, particle sizes and size distributions, lattice point deviations, finite domain sizes, orientational distributions, core/shell-structures as well a variety of peak shapes. The expressions allow to quantitatively describe, model and even fit measured SAXS and SANS-patterns of ordered or oriented micellar solutions, lyotropic phases, block copolymers, colloidal solutions, nanocomposites, photonic crystals, as well as mesoporous materials.

20.
J Chem Phys ; 130(24): 244901, 2009 Jun 28.
Article in English | MEDLINE | ID: mdl-19566175

ABSTRACT

We study the influence of mutual interaction on the conformation of flexible poly(propyleneamine) dendrimers of fourth generation in concentrated solution. Mixtures of dendrimers with protonated and deuterated end groups are investigated by small-angle neutron scattering up to volume fractions of 0.23. This value is in the range of the overlap concentration of the dendrimers. The contrast between the solute and the solvent was varied by using mixtures of protonated and deuterated solvents. This allows us to investigate the partial structure factors of the deuterated dendrimers in detail. An analysis of the measured scattering intensities reveals that the shape of the flexible dendrimers is practically independent of the concentration in contrast to the pronounced conformational changes in flexible linear polymers.

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