Small-angle x-ray scattering studies of human breast tissue samples

Small-angle x-ray scattering (SAXS) patterns are recorded from thin breast tissue samples containing healthy and cancerous regions. The SAXS patterns are compared with histo-pathological observations. The information available from SAXS is reviewed, and a model for scattering from collagen is presented. Scattering patterns of collagen at regions far from the tumours are essentially different from those at tumours. The axial period of collagen fibrils is 65.0 +/- 0.1 nm in healthy regions, and 0.3 nm larger in cancer-invaded regions. The average intensity of scattering from cancerous regions is an order of magnitude higher than the intensity from healthy regions. This is interpreted to arise from an increase of the specific surface area of the scatterers, which is due to a disruption of the molecular and supra-molecular structures in cancerous regions and invasion of new types of cells. The differences of the SAXS patterns are large and distinctive enough to suggest that these phenomena may be utilized in mammography.

Microscopic mechanisms of electric-field-induced alignment of block copolymer microdomains

We investigate the microscopic mechanisms responsible for microdomain alignment in block copolymer solutions exposed to an electric field. Using time-resolved synchrotron small-angle x-ray scattering, we reveal two distinct processes, i.e., grain boundary migration and rotation of entire grains, as the two dominant microscopic mechanisms. The former dominates in weakly segregating systems, while the latter is predominant in strongly segregated systems. The kinetics of the processes are followed as a function of polymer concentration and temperature and are correlated to the solution viscosity.

A microscopic look at the reinforcement of silica-filled rubbers

The deformed structure of silica-filled elastomers under uniaxial strain has been investigated using a combination of both small angle x-ray scattering and small angle neutron scattering methods. Using an extraction procedure and taking into account the two-phase nature of these polymer-based composites, the single chain scattering behavior as well as filler properties could be obtained uniquely on identical samples. For the first time the deformation of the rubbery matrix on the length scale of the network chain in a filled rubber could be determined and therewith the importance of matrix overstrain for the mechanical properties was estimated. Additionally, the determination of filler deformation and filler destruction presents microscopic details of the mechanisms of filler networking and the stress-softening Mullins effect.

New sources and instrumentation for neutrons in biology

Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.

Neuroendoscopic technique for the operative treatment of septated syringomyelia

The management of septated, chambered syringomyelia has until now been problematic because the usual operative methods cannot secure drainage of all chambers of the cavity. The development of a flexible neuroendoscope affords the possibility to perforate the septa under visual control which subdivide the cavity. We present our experiences with 11 cases of septated syringomyelia, which have been operated upon using a flexible neuroendoscope.

Combined small- and wide-angle X-ray scattering study of early stages of polymer crystallization

The early stage of melt crystallization in low-density polyethylene was investigated by simultaneous time-resolved small-angle and wide-angle X-ray scattering (SAXS/WAXS) techniques. The high detectivity of the two-dimensional detectors together with the large photon flux of an undulator source permitted the collection of SAXS and WAXS patterns with nearly single-photon sensitivity and sub-second time resolution. As a result, the crystalline fraction well below 0.001 can be reliably detected and the apparent induction time is considerably reduced (<10 s). The time evolution of both the SAXS invariant and the degree of crystallinity follow the well established Avrami-type growth law. Despite the orders of magnitude improvement in sensitivity, the difference in the onset time of SAXS and WAXS signals is not significant. The behaviour of the SAXS data in the very early stages is not consistent with spinodal decomposition mechanism as described by the linearized Cahn–Hilliard theory.

A tactile feedback hexapod operating robot for endoscopic procedures

This paper describes a test prototype for precision robot-assisted surgery using a hexapod operating robot and a movable operating cockpit for tactile feedback. The objective of the work described is twofold: 1, to evaluate the use of hexapod robots for precisely manipulating endoscopes and surgical instruments in submillimeter surgery; 2, to test a new user interface concept based on tactile feedback. Based on the principle of a flight simulator, the aim is to give the surgeon motion cues in addition to the endoscope image, to assist his spatial orientation. The paper gives a detailed description of the system components and the potential applications.

The Impact of COVID-19 Pandemic on Prevalence of Diabetic Ketoacidosis at Diagnosis of Type 1 Diabetes: A Single-Centre Study in Central Pennsylvania

Objective

We conducted this study to investigate whether the COVID‐19 pandemic impacted the rate of DKA and previously identified risk factors in children presenting with T1D.

Methods

We performed an extension of a retrospective analysis of all paediatric patients (age ≤ 18) newly diagnosed with T1D within a tertiary care referral centre between 01/01/2017 and 09/14/2020. Demographics, insurance coverage and clinical documents 30 days before their T1D diagnosis were abstracted to assess for symptoms at diagnosis, laboratory values (blood glucose, HbA_1c, venous pH and bicarbonate) and any healthcare encounters within 30 days of their diagnosis of T1D.

Results

412 patients with T1D [171 F:241 M; 370 pre‐COVID era:42 post‐COVID era] were included. The percentages of DKA diagnoses at admission were very similar between the pre‐COVID and post‐COVID groups (47% vs. 48%), as were the severity (13% vs. 14% mild DKA; 33% vs. 31% moderate or severe DKA).

Conclusion

There were no fluctuations in the rate of DKA among paediatric patients newly diagnosed with T1D throughout the coronavirus pandemic in central Pennsylvania.

[Reliability of active range-of-motion measurement of the rotation in the forearm: comparison of three measurement devices]

AIM

The aim of this study is to prove the intra- and interobserver reliability of three different methods to measure the active range-of-motion in the forearm.

METHODS

These three different methods were tested on forty volunteers. In the first method pictures were made in full supination and pronation, measurement of the two angles was performed with a dedicated software. Active range-of-motion was defined as the magnitude of forearm rotation between maximum pronation and supination. The second method used a standard goniometer. The third method of assessment used a gravity goniometer (plurimeter). We randomised both the side of the patient to be examined and the sequence of the methods. Two examiners measured subsequently the range-of-motion twice with these three devices.

RESULTS

We found a significant intraobserver reproducibility with the gravity goniometer. There was no significance with the goniometer or pictures. The intraobserver reproducibility of the latter two methods was poor. The interobserver reproducibility of the gravity goniometer and pictures was significant, for the goniometer it was poor. Agreement between the pictures and gravity goniometer assessment of the range-of-motion was good. None of these two methods was significantly correlated with the goniometer assessment.

CONCLUSION

For reproducibility of measurement of range-of-motion in the forearm the gravity goniometer is the best method, although the measured values were 5 % greater.