GO-Enabled Bacterial Cellulose Membranes by Multistep, In Situ Loading: Effect of Bacterial Strain and Loading Pattern on Nanocomposite Properties

This paper presents the results of research on the preparation and properties of GO/BC nanocomposite from bacterial cellulose (BC) modified with graphene oxide (GO) using the in situ method. Two bacterial strains were used for the biosynthesis of the BC: Komagataeibacter intermedius LMG 18909 and Komagataeibacter sucrofermentans LMG 18788. A simple biosynthesis method was developed, where GO water dispersion was added to reinforced acetic acid-ethanol (RAE) medium at concentrations of 10 ppm, 25 ppm, and 50 ppm at 24 h and 48 h intervals. As a result, a GO/BC nanocomposite membrane was obtained, characterized by tensile strength greater by 150% as compared with the pure BC (̴ 50 MPa) and lower volume resistivity of ~4 ∙ 10⁹ Ω × cm. Moreover, GO addition increases membrane thickness up to ~10% and affects higher mass production, especially with low GO concentration. All of this may indicate the possibility of using GO/BC membranes in fuel cell applications.

Preparation and properties of composite cellulose fibres with the addition of graphene oxide

The paper presents the results of a study on the preparation of cellulose-based composite fibres (CEL) with graphene oxide addition (GO). Composite fibres (GO/CEL) were prepared via the wet spinning method from CEL solutions in 1-ethyl-3-methylimidazolium acetate (EMIMAc) that contained a nano-addition of GO dispersion in N,N-dimethylformamide (DMF). The GO contents of the composite fibres were 0, 0.21, 0.50, 0.98, and 1.97 % w w. The fibres were coagulated in two solvents: distilled water and methanol. The results demonstrated that the amount of GO additive and the type of coagulant significantly impact the physicochemical, mechanical and structural properties of the CEL and GO/CEL fibres. The use of distilled water in a coagulation bath causes a degree of crystallinity of 31.0-40.8 % (WAXS) and a shift in the thermal decomposition temperature (by approximately 19 °C) towards higher temperatures (TGA). The results demonstrate improvements in the mechanical properties of the GO/CEL fibres, which were at the level of 9.43-14.18 cN/tex. In addition, the GO/CEL fibres exhibit satisfactory GO dispersion throughout their volume.

Research lessons from implementing a national nursing workforce study

BACKGROUND

National nursing workforce studies are important for evidence-based policymaking to improve nursing human resources globally. Survey instrument translation and contextual adaptation along with level of experience of the research team are key factors that will influence study implementation and results in countries new to health workforce studies.

AIM

This study's aim was to describe the pre-data collection instrument adaptation challenges when designing the first national nursing workforce study in Poland while participating in the Nurse Forecasting: Human Resources Planning in Nursing project.

METHODS

A descriptive analysis of the pre-data collection phase of the study. Instrument adaptation was conducted through a two-phase content validity indexing process and pilot testing from 2009 to September 2010 in preparation for primary study implementation in December 2010. Means of both content validation phases were compared with pilot study results to assess for significant patterns in the data.

RESULTS

The initial review demonstrated that the instrument had poor level of cross-cultural relevance and multiple translation issues. After revising the translation and re-evaluating using the same process, instrument scores improved significantly. Pilot study results showed floor and ceiling effects on relevance score correlations in each phase of the study.

LIMITATIONS

The cross-cultural adaptation process was developed specifically for this study and is, therefore, new. It may require additional replication to further enhance the method.

CONCLUSIONS

The approach used by the Polish team helped identify potential problems early in the study. The critical step improved the rigour of the results and improved comparability for between countries analyses, conserving both money and resources. This approach is advised for cross-cultural adaptation of instruments to be used in national nursing workforce studies.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

Countries seeking to conduct national nursing workforce surveys to improve nursing human resources policies may find the insights provided by this paper useful to guide national level nursing workforce study implementation.

Fitting a single-phase model to the post-exercise changes in heart rate and oxygen uptake

The kinetics of post-exercise heart rate (HR) and oxygen consumption (EPOC) was studied in 10 elite cyclists subjected to four laboratory cycle ergometer maximal exercises lasting 30, 90, 180 or 360 s. Heart rate and oxygen uptake (VO2) were recorded over a period of 6 min after the exercise. By applying the logit transformation to the recorded variables and relating them to the decimal logarithm of the recovery time, uniform single-phase courses of changes were shown for both variables in all subjects and exercises. This enabled computing half-recovery times (t(1/2)) for both variables. Half-time for VO2 negatively correlated with square root of exercise duration (within-subject r = -0.629, p < 0.001), the total post-exercise oxygen uptake till t(1/2) was thus constant irrespectively of exercise intensity. The method is simple and enables reliable comparisons of various modes of exercise with respect to the rate of recovery.

Changes in prolactin and testosterone levels induced by acute physical exertion in young female athletes

In order to establish the influence of acute atypical exercise on prolactin and testosterone levels in young female athletes the authors selected a group of 13 short distance runners who were subjected to exercise on a cycle ergometer. Hormone levels were measured before the test, just after the end of test, 30 and 90 minutes thereafter. Significant increase in testosterone concentration appeared immediately after the exercise and 90 minutes after completion of a test testosterone level returned to preexercise levels. Unlike the results of other authors statistically significant decrease in plasma prolactin concentration was found 90 minutes after the end of test.