Open Access

Entwicklung und Optimierung einer Methode zur Bestimmung der antioxidativen Aktivität von Kraft- und Organosolv-Lignin via Folin- Ciocalteu-Assay

Although work events can be regarded as pivotal elements of organizational life, only a few studies have examined how positive and negative events relate to and combine to affect work engagement over time. Theory suggests that to better understand how current events affect work engagement (WE), we have to account for recent events that have preceded these current events. We present competing theoretical views on how recent and current work events may affect employees (e.g., getting used to a high frequency of negative events or becoming more sensitive to negative events). Although the occurrence of events implies discrete changes in the experience of work, prior research has not considered whether work events actually accumulate to sustained mid-term changes in WE. To address these gaps in the literature, we conducted a week-level longitudinal study across a period of 15 consecutive weeks among 135 employees, which yielded 849 weekly observations. While positive events were associated with higher levels of WE within the same week, negative events were not. Our results support neither satiation nor sensitization processes. However, high frequencies of negative events in the preceding week amplified the beneficial effects of positive events on WE in the current week. Growth curve analyses show that the benefits of positive events accumulate to sustain high levels of WE. WE dissipates in the absence of continuous experience of positive events. Our study adds a temporal component and informs research that has taken a feature-oriented perspective on the dynamic interplay of job demands and resources.

The three pillars of organization and leadership are discussed as being fundamental because they enable organizations to continuously synchronize with business needs and opportunities and enable their employees to interact flexibly and successfully. The building blocks or pillars are interconnected with agile practices such as iterative procedures and minimum viable solutions. They also challenge our learning abilities beyond enriching our inner maps, i.e., adapting them and even managing their adaption.

High-precision, multidimensional holes are required in many technical applications. Due to its undercut shape, these kind of holes are usually manufactured from two sides of the work piece including a time-consuming co-axial alignment. Compared to current state of the art, a one-sided drilling strategy has numerous advantages regarding flexibility, precision and process efficiency. In this work, a helical drilling optic and an ultrashort pulse laser are utilized to fabricate a rotationally symmetric multidimensional-shaped hole in one single process step. The influences of single pulse energy, pulse repetition rate, rotation speed of laser beam as well as the drilling time on ablation depth are investigated. By varying the pulse energy and pulse density, the deposited energy per unit length on the single helical path can be adapted and thus the ablation depth can be scaled. With the adapted laser energy deposition, a T-shaped hole with a uniformed depth of about 80 mu m inlet is fabricated. Morphological analysis on the hole wall show excellent drilling quality without recast layers or heat-affected zones and roughness Rq < 0.35 mu m.

Im Interview erklärt IT-Security-Experte Professor Dr. Hartmut Pohl die gravierenden Umwälzungen, die das „IT-Sicherheits gesetz 2.0“ in seiner bekannt gewordenen Fassung für Wirtschaft, Gesellschaft und Technik bringen wird, wo es zu kurz greift und über das Ziel hinausschießt.

Atmospheric aerosols affect the power production of solar energy systems. Their impact depends on both the atmospheric conditions and the solar technology employed. By being a region with a lack in power production and prone to high solar insolation, West Africa shows high potential for the application of solar power systems. However, dust outbreaks, containing high aerosol loads, occur especially in the Sahel, located between the Saharan desert in the north and the Sudanian Savanna in the south. They might affect the whole region for several days with significant effects on power generation. This study investigates the impact of atmospheric aerosols on solar energy production for the example year 2006 making use of six well instrumented sites in West Africa. Two different solar power technologies, a photovoltaic (PV) and a parabolic through (PT) power plant, are considered. The daily reduction of solar power due to aerosols is determined over mostly clear-sky days in 2006 with a model chain combining radiative transfer and technology specific power generation. For mostly clear days the local daily reduction of PV power (at alternating current) (PVAC) and PT power (PTP) due to the presence of aerosols lies between 13 % and 22 % and between 22 % and 37 %, respectively. In March 2006 a major dust outbreak occurred, which serves as an example to investigate the impact of an aerosol extreme event on solar power. During the dust outbreak, daily reduction of PVAC and PTP of up to 79 % and 100 % occur with a mean reduction of 20 % to 40 % for PVAC and of 32 % to 71 % for PTP during the 12 days of the event.

Walking has always been considered as the gold standard for navigation in Virtual Reality research. Though full rotation is no longer a technical challenge, physical translation is still restricted through limited tracked areas. While rotational information has been shown to be important, the benefit of the translational component is still unclear with mixed results in previous work. To address this gap, we conducted a mixed-method experiment to compare four levels of translational cues and control: none (using the trackpad of the HTC Vive controller to translate), upper-body leaning (sitting on a "NaviChair", leaning the upper-body to locomote), whole-body leaning/stepping (standing on a platform called NaviBoard, leaning the whole body or stepping one foot off the center to navigate), and full translation (physically walking). Results showed that translational cues and control had significant effects on various measures including task performance, task load, and simulator sickness. While participants performed significantly worse when they used a controller with no embodied translational cues, there was no significant difference between the NaviChair, NaviBoard, and actual walking. These results suggest that translational body-based motion cues and control from a low-cost leaning/stepping interface might provide enough sensory information for supporting spatial updating, spatial awareness, and efficient locomotion in VR, although future work will need to investigate how these results might or might not generalize to other tasks and scenarios.