Destruction of cement composites occurs due to the alternate or simultaneous effects of aggressive media, resulting in the destruction of concrete under the influence of chemical and physical ...factors. This article presents the results of changes in the measurement of linear strains of samples and changes in the microstructure of cement after 30 freezing and thawing cycles and immersed in 5% sodium sulfate solution. The compressive strengths ratios were carried out at the moment when the samples were moved to the sulfate solution after 30 cycles and at the end of the study when the samples showed visual signs of damage caused by the effect of 5% Na
SO
. The composition of the mixtures was selected based on the Gibbs triangle covering the area up to 40% replacement of Portland cement with low and high-calcium fly ashes or their mixture. Air-entrained and non-air entrained mortars were made of OPC, in which 20%, 26.6%, and 40% of Portland cement were replaced with low and/or high-calcium fly ash. Initial, freezing and thawing cycles accelerated the destruction of non- air-entrained cement mortars immersed in 5% sodium sulfate solution. The sulfate resistance, after the preceding frost damage, decreased along with the increase in the amount of replaced fly ash in the binder. Air-entrained mortars in which 20% of cement was replaced with high-calcium fly ash showed the best resistance to the action of sodium sulfate after 30 freezing and thawing cycles.
In the current literature, many non-covalent interaction (NCI) donors have been proposed that can potentially catalyze Diels-Alder (DA) reactions. In this study, a detailed analysis of the governing ...factors in Lewis acid and non-covalent catalysis of three types of DA reactions was carried out, for which we selected a set of hydrogen-, halogen-, chalcogen-, and pnictogen-bond donors. We found that the more stable the NCI donor-dienophile complex, the larger the reduction in DA activation energy. We also showed that for active catalysts, a significant part of the stabilization was caused by orbital interactions, though electrostatic interactions dominated. Traditionally, DA catalysis was attributed to improved orbital interactions between the diene and dienophile. Recently, Vermeeren and co-workers applied the activation strain model (ASM) of reactivity, combined with the Ziegler-Rauk-type energy decomposition analysis (EDA), to catalyzed DA reactions in which energy contributions for the uncatalyzed and catalyzed reaction were compared at a consistent geometry. They concluded that reduced Pauli repulsion energy, and not enhanced orbital interaction energy, was responsible for the catalysis. However, when the degree of asynchronicity of the reaction is altered to a large extent, as is the case for our studied hetero-DA reactions, the ASM should be employed with caution. We therefore proposed an alternative and complementary approach, in which EDA values for the catalyzed transition-state geometry, with the catalyst present or deleted, can be compared one to one, directly measuring the effect of the catalyst on the physical factors governing the DA catalysis. We discovered that enhanced orbital interactions are often the main driver for catalysis and that Pauli repulsion plays a varying role.
Feeling Safe in the Dark Boomsma, Christine; Steg, Linda
Environment and behavior,
02/2014, Letnik:
46, Številka:
2
Journal Article
Recenzirano
Odprti dostop
This research examined to what extent physical factors, notably lighting and entrapment (blocked escape), and individual factors, notably gender, affect feelings of safety and the acceptability of ...reduced lighting levels. The authors reasoned that acceptability of reduced street lighting depends on perceived safety, which in turn depends on entrapment, lighting, and gender. Virtual representations of a residential street were used, systematically manipulating entrapment and lighting levels. As expected, people felt less safe in lower lighting and higher entrapment settings, and these settings were evaluated as less acceptable. Although women perceived a situation as less safe compared with men, the authors found no gender differences in acceptability, which extends previous research. Importantly, as hypothesized, perceived safety mediated the effect of lighting on acceptability levels, suggesting that people can accept lower lighting levels when social safety is not threatened.
To attract a mate, females of most moth species synthesize and emit sex pheromone from a specific gland in a behavior termed “calling”. In a broad temporal sense, calling behavior and pheromone ...synthesis are synchronized through the overlap of their circadian rhythms. However, the limited amount of pheromone a female produces each day must be managed so that pheromone is emitted at a sufficient (to attract males) mass emission rate (MER) over the entire calling period, typically many hours. We are studying pheromone synthesis and emission in the moth
Chloridea
(formerly
Heliothis
)
virescens
(family Noctuidae). One way that female
C
.
virescens
manage pheromone over their calling period is by calling intermittently; the period between calling bouts allows females to replenish pheromone, and resume calling at high MERs. However, militating against replenishment is loss of pheromone through putative catabolism. In this paper, we examined three aspects pertaining to pheromone MER in
C
.
virescens
: (i) the effect of adult feeding on calling behavior, (ii) the effect of certain behavioral/physical parameters on MER, and (iii) the relative loss (putative catabolism) of pheromone in retracted (non-calling) and everted (calling) glands. We found that (i) adult feeding increases calling duration, consistent with the known concomitant increase in pheromone production, (ii) various physical factors relating to the gland, including degree of eversion (surface area), orientation to airstream, and air velocity over the gland influence MER, and (iii) putative catabolism occurs in both retracted and everted glands, but substantially less pheromone is lost in the everted gland primarily because of the high MER when the gland is first everted. Together, these data demonstrate that, over the calling period, the efficient use of pheromone for emission by female
C
.
virescens
is dependent on the interaction among synthesis, storage, catabolism, and calling behavior.
Purpose
To evaluate the effects of kinesiophobia on the outcomes of total knee arthroplasty (TKA), and to investigate whether kinesiophobia represents an independent factor influencing the surgery ...success or whether the observed effects are driven by other physical or psychological aspects such as anxiety and depression.
Methods
Two hundred patients were evaluated prospectively (mean age 65.7 ± 9.1 years, 134 women and 66 men) at 12 months after TKA. Kinesiophobia was assessed with the Tampa Scale for kinesiophobia (TSK: Activity Avoidance—TSK1 and Harm—TSK2 subscales); anxiety and depression were assessed with STAI and BDI, respectively, and preoperative pain and function, sex, age, BMI, education level, number of painful joints and years of symptoms’ duration before surgery were documented as well. Results were evaluated with pain and function on 0–10 numeric rating scales, while the overall clinical outcome was documented with WOMAC and SF-12 (Physical and Mental subscales) scores.
Results
TSK1 was correlated with WOMAC results at 12 months (
p
= 0.005,
ρ
= 0.197). STAI (
p
= 0.002,
ρ
= 0.222), BDI (
p
< 0.0005,
ρ
= 0.307), and sex (
p
= 0.004) also influenced the outcome after TKA, while other parameters, such as age, BMI, education level, and number of painful joints and years of symptoms’ duration before surgery, did not correlate with the clinical outcome. The multivariate analysis confirmed the role of BDI (
p
= 0.006, partial
η
2
= 0.038), TSK1 (
p
= 0.011, partial
η
2
= 0.033), and sex (
p
= 0.048, partial
η
2
= 0.020), and a synergic interaction of BDI and TSK1, which together presented an even stronger correlation (
p
< 0.0005, partial
η
2
= 0.111) with WOMAC at 12-month follow-up.
Conclusions
Kinesiophobia is a factor influencing the outcome after TKA independently from other psychological and physical variables. This risk factor may affect TKA results, especially in women, and shows a further synergic interaction with depression in terms of lower surgical outcome. These findings are of clinical relevance because they show the impact of psychological factors such as kinesiophobia, and suggest the possibility of adopting co-interventions to overcome the fear of physical activity, and in the end improve patient recovery and final outcome after TKA.
Level of evidence
IV.
A highly visible form of soil erosion is gully, a significant geomorphological feature, resulting from water erosion and causing land degradation and deterioration. In arid and semi-arid environment, ...gully erosion is conceived as an important source of sediment supply washing out the top fertile soil and exposing lower soil layers. The present study is conducted on the lateritic terrain of Rupai watershed of eastern plateau fringe of India, where water erosion is a serious concern. In order to prepare a gully erosion vulnerability mapping, the analytical hierarchy process (AHP) model coupled with geospatial technology is adopted taking into account thirteen bio-physical factors. It is revealed that around 49% area of the watershed belongs to high to very high gully erosion vulnerability zone (GEVZ) followed by moderate risk zone of 31.64%. This model is validated performing an accuracy assessment, which is calculated to be 90.91%, and the value of Kappa co-efficient is 0.86. It is imperative to estimate the average annual soil loss alongside of delineating GEVZ; thus, the revised universal soil loss equation (RUSLE) model is used with geospatial technology. It unveils that the average estimated soil loss of the watershed varies from < 15 to 431 t ha
−1
y
−1
. Around 29% of the study area experiences high to very high (57 to > 147 t ha
−1
y
−1
) soil erosion risk, where 68% area endures low level of soil erosion risk (< 15 t ha
−1
y
−1
). The study of gully morphology depicts gully depth ranging from < 1 to 5 m (small to medium gully) with
V
and
U
shapes. Results obtained from this study may help in planning and management of land use and soil erosion conservation.
In their recent article Wang et al. (2016) analyzed observations from EISCAT (European Incoherent Scatter) Scientific Association Russian X‐mode heating experiments and claimed to explain the ...potential mechanisms for the parametric decay instability (PDI) and oscillating two‐stream instability (OTSI). Wang et al. (2016) claim that they cannot separate the HF‐enhanced plasma and ion lines excited by O or X mode in the EISCAT UHF radar spectra. Because of this they distinguished the parametric instability excited by O‐/X‐mode heating waves according to their different excitation heights. Their reflection heights were determined from ionosonde records, which provide a rough measure of excitation altitudes and cannot be used for the separation of the O‐ and X‐mode effects. The serious limitation in their analysis is the use of a 30 s integration time of the UHF radar data. There are also serious disagreements between their analysis and the real observational facts. The fact is that it is the radical difference in the behavior of the X‐ and O‐mode plasma and ion line spectra derived with a 5 s resolution, which provides the correct separation of the X‐ and O‐mode effects. It is not discussed and explained how the parallel component of the electric field under X‐mode heating is generated. Apart from the leakage to the O mode, results by Wang et al. (2016) do not explain the potential mechanisms for PDI and OTSI and add nothing to understanding the physical factors accounting for the parametric instability generated by an X‐mode HF pump wave.
Plain Language Summary
In their recent article Wang et al. (2016) analyzed results from EISCAT (European Incoherent Scatter) Scientific Association active experiments and claimed to explain the potential mechanisms for processes occurring in the near‐Earth space environment. There are serious disagreements between their analysis and the real observational facts. We reanalyzed the observations described by Wang et al. (2016) (WANG2016) and demonstrated that their results are flawed and incorrect. We then review WANG2016 step by step to disclose the flaws and failures of their analysis of observations.
Key Points
The separation of the O‐ and X‐mode effects by Wang et al. (2016) is incorrect
The analysis of UHF radar observations by Wang et al. (2016) is failed and incorrect
Wang results not in agreement with observational facts
BackgroundJob Exposure Matrices (JEM) are rarely used to estimate work-related physical exposures; few studies have compared JEM exposures to other methods. Using existing data from a prospective ...cohort study of carpal tunnel syndrome (CTS) in the US, we compared associations between physical factors and incident CTS using different exposure estimates: individual level job observations, a JEM that pooled these observations at the job level, and a JEM based on O*NET, a publicly available US dataset describing the physical requirements of different occupations.MethodsWorkers were recruited from >50 US workplaces and followed from baseline examination for incident CTS. Direct observations and video analysis were used to estimate hand force and activity. We studied 4 observed exposures associated with incident CTS in previous publications from this cohort, and selected a priori from O*NET 5 exposures corresponding to these same domains. Cox proportional hazards models included age, gender, body mass index, and study site. Exposure variables were dichotomized at the median of their respective distributions.ResultsWe analysed 2,393 workers, representing 3617 person years and 140 incident cases of CTS. Statistically significant HRs were found for the individually observed exposures of hand exertion, time in forceful hand exertion, and Hand Activity Level (HAL). Analysis using exposures derived from both JEMs demonstrated similar associations, although the confidence intervals were wider, and effect sizes using the O*NET data (HRs from 1.3 to 1.8) were somewhat smaller than those calculated using individually observed exposures (HRs from 1.5 to 1.9).ConclusionsIn a large population study of CTS, exposures assigned via a JEM derived from publicly available physical exposure data found similar though somewhat weaker associations than exposures assessed via direct observation of individual workers. Use of JEM allows studies that are otherwise infeasible, and is an appropriate study design for some studies of MSD.
We propose to adopt a non-isothermal and colloid type cluster–cluster aggregation stochastic model aimed at comprehending the temperature driven and polymer swelling accompanying volume expansion ...encountered in microgels. The nonequilibrium nature of the process is captured by describing expansion characteristics with simplified power laws, indicating the scalability of properties with time and temperature. Additionally, molecular dynamics simulations of the presented mechanism for a chosen biopolymer have been performed. This can be of interest for experimenters working in the field of nonequilibrium phase transitions, and fairly prospectively, within the area of thermal phonon-involving technology. In these areas, scanning the system’s temperature, or sometimes tuning similar dissipation-addressing physical factors, such as pH, appears to be a fairly pivotal examination case.
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