Influence of Relative Humidity on the Expansion Coefficient Rate of Bamboo Bundles

Bamboo can be used for a variety of purposes, whether using the bamboo culm in structures works or using bamboo bundle or bamboo fibers as a reinforcement in composite materials. However, the critical item that should be considered when using bamboo materials is the humidity condition of the environment. The influence of humidity on the mechanical properties of bamboo materials can potentially lead to damage or degradation. The objective of this research is to investigate the influence of relative humidity (RH) on elastic modulus of bamboo bundle. In this research, 3 years old Dendrocalamus bamboo stem at 3-6 m in height without node was used to prepare the bundle samples. The bamboo stem was dried in the oven at 105 °C then hand pulled and cut to get the bamboo bundle with 30 mm in gage length and 0.06-0.09 mm 2 in cross-section areas. The elastic modulus of bamboo bundles was determined according to ASTM D3379 standard under 8 different relative humidity; 30%, 35%, 50%, 55%, 70%, 75%, 80%, and 85% RH, whereas paper grips technique was applied to prevent damage from the machine clamps. The results indicated that the relative humidity does not affect the value of the loaded or unloaded elastic modulus of bamboo fiber bundle. For the low value of relative humidity, here 35%-55%, the value of elastic modulus of bamboo bundle is quasi-stable with the RH with the average value 25.93 GPa while the elastic modulus was gradually decreased for the high value of RH (>70%) with the minimum value of 24.43 GPa at 85% RH. Implying at high humidity condition, the humidity or the amount of water vapor in the air affects to the bamboo bundle be softened or more flexible, which helps the process of bending or forming bamboo bundles easier.

Environmental conditions such as temperature and relative humidity influence the rate of evaporation of moisture from the concrete pore structure. They therefore have a direct influence on the development of transport properties, which are related to durability. Portland cement concretes of various grades were wet cured for different periods of time and exposed to controlled environmental conditions. The influences of temperature, relative humidity, and wind speed on potential durability of the cover layer were assessed by means of durability index parameters related to the transport processes of oxygen permeability, water sorptivity, and chloride conductivity. Temperature, in the range 18 to 35°C, had the most significant influence on the results. The effect of elevated temperatures on evaporation and hydration resulted in either significant reductions or improvements of potential durability. The influence of relative humidity, in the range 50 to 65%, was less significant. Exposure to 82% relative humidity resulted in significant improvements in the indexes of poorly cured concretes, while well-cured concretes were insensitive to changes in relative humidity. The influence of wind speed on potential durability was insignificant.

Threats related to climate change are becoming increasingly intense, frequent, and complex. The main manifestations of these changes include rising air temperatures, increased frequency of certain atmospheric phenomena, and altered precipitation patterns, which have drawn the attention of many researchers. However, changes in relative air humidity often remain insufficiently studied. The purpose of this paper is to examine the annual regime, multi-year (1977−2020) dynamics, and spatial distribution of average annual, monthly, and seasonal values of relative air humidity in the Volyn region. To achieve this goal, the following tasks were defined: to review the history of foreign and domestic research on climate change, particularly focusing on the dynamics of relative air humidity in the context of global warming; to analyze the annual patterns of relative air humidity; to investigate the seasonal regime and spatio-temporal dynamics of relative air humidity in the Volyn region; to identify trends in changes in average annual and monthly relative air humidity at weather stations in the region during 1977−2020; to analyze spatial differences in relative humidity indicators in the Volyn region during different months of the year. Methodology. The study employed methods of induction, deduction, synthesis, comparative analysis, and mathematical-statistical and graphical techniques (using Microsoft Excel 2019). Cartographic modeling was performed using GS Surfer. Statistical significance of trends in average annual and monthly relative humidity series was assessed by evaluating correlation coefficients (R), based on the ratio R/σR ≥ β. At the 5% significance level or 95% confidence interval, 𝛽=2. The research results indicate that the average annual relative humidity in the Volyn region during 1977−2020 was 78.5%, with a gradual decrease over time (the linear trend is statistically significant). Relative humidity is highest in November and December (87%) and lowest in April and May (70%). Among the seasons, winter exhibits the highest relative air humidity (85%), while spring shows the lowest (72%). During the studied period, a notable decline in relative air humidity was observed in summer and spring. Monthly analysis revealed decreasing trends in relative humidity in March, April, June, July, August, and September at all weather stations, while increasing trends were noted in November and December. The main trends in relative humidity changes in the Volyn region are: decreasing average annual and monthly values of relative humidity from March to September and increasing values in November and December; increasing relative air humidity during the cold season in the northern and central parts of the region (e.g., weather stations at Svityaz, Kovel, and Lyubeshiv); decreasing relative air humidity in the southern and southeastern parts of the region (e.g., weather stations at Volodymyr, Lutsk, and Manevychi) during February–October. Value/Originality For the first time, trends in average monthly, seasonal, and annual relative humidity values were analyzed at all weather stations in the Volyn region for the period 1977−2020. This study characterizes the annual and seasonal distribution of relative air humidity and maps the spatial differences in relative air humidity values across the region during different months of the year.

A long period grating (LPG) coated with polyvinyl alcohol has been developed and evaluated through exposure to a range of relative humidity (RH) levels (from 33%RH to 97%RH). The conditions for the creation of the sensor probes are described and the response of the device in terms of changes in the resonance loss of several of the spectral loss bands has been monitored. In order to make comparative measurements, a noncoated LPG was exposed to various known refractive index (RI) conditions and the grating response was monitored, analyzed and the results evaluated. This is then related to the change in RH when the sensor is exposed to various RH levels, as the coating RI changes, leading to the change in resonance loss. The PVA coated LPG sensor is showing a relatively fast response time of ~ 80 s to reach 97%RH from 33%RH and inducing ~ 2 dB change in transmission of resonance loss band.

Influence of temperature and relative humidity on early bond strengths to dentine

In this paper, a new bamboo glulam is proposed. The material fully utilizes the characteristics of the hollow bamboo culm and easy integration of bamboo bundles, and realizes a hollow bamboo glulam. A three-dimension finite element model of the bamboo culm integrated bamboo bundle glulam was established using the continuum damage mechanics and cohesion element model, and the failure process of the glulam material under the tensile load was analysed. The results show that the fibers in the 1st and 2nd plys of the 90° bamboo bundles were stretched and failed, and the fibers in the 1st and 2nd plys of the 0° bamboo bundles didn’t fail. 90° bamboo bundles ply 2 matrix compression failure occurred, the bamboo culm integrated bamboo bundles glulam tensile strength is 4 times higher than bamboo bundles glulam.

Reconstructing past environmental conditions using proxies based on fossil and subfossil leaves is difficult because leaf form is influenced by many interacting environmental factors such as temperature, CO2 concentration, light, soil water availability and, potentially, atmospheric relative humidity (RH). We used a species important for palaeo-environmental reconstruction, the southern beech, Nothofagus cunninghamii, to test for the effects of a 50% difference in RH on leaf morphology and epidermal anatomy in a glasshouse experiment. Leaf size, shape and thickness were all strongly affected by RH with leaves from high humidity being larger, narrower and thicker than those from low humidity regardless of plant accession. RH impacts on epidermal characters were generally slight and dependent upon accession. In particular, epidermal cell size was remarkably consistent across accessions and RH levels. Thus, gross leaf morphology of N. cunninghamii was sensitive to changes in RH but, on average, epidermal characters were not. Thus, palaeoenvironmental signals from the epidermis of this species are unlikely to be affected by variation in RH, provided sufficient numbers of leaves are investigated. Gross leaf morphology, however, was strongly related to RH and should not be used for palaeo-climatic reconstruction if changes in RH are likely.

Introduction:According to the World Health Organization estimates annually in the world die due to CVI every sixth women and 10th man. This paper is the research of the correlation between changes in relative air humidity and stroke (CVA) in the Sarajevo Canton. Included are patients who experienced an acute stroke in the Canton of Sarajevo and treated in the pre hospital phase by the staff of the Institute for Emergency Medicine. Days with stroke and those without cases of stroke were compared within three years and meteorological data for those days were obtained by the Weather Bureau of Federation of Bosnia and Herzegovina. Meteorological data include measurements of average humidity every day at 7, 14 and 21 o’clock in three years.Aim:To evaluate the significance of the influence of humidity on the incidence of CVI’s. Show the trend towards CVI in the reporting period and is it correlated with the trend of change in relative humidity in those days. Correlate the incidence of stroke as determined in relation to gender, age and selected climatic parameter.Material and Methods:This article presents a retrospective study. Subjects were patients of Emergency Medical Care Institute in Sarajevo, which in the period from 2004 to 2006 had a CVI. Included are patients who had a working diagnosis of stroke for the first time or as a repeated stroke. Analysis of cases of stroke was carried out by gender, age, days and seasons by descriptive-analytical epidemiological methods.Results:In total were registered 1930 patients during three years period. According to years of research in 2004–635, 2005-616 and 2006 – 679. It was found that when testing the null hypothesis about the effects of humidity in two months with a maximum stroke in the year and days without CVI and relative humidity only in 2005 had a statistically significant effect on the incidence of stroke, while during the other two years of the study there was no impacts. It turned out that the extreme values of relative humidity of the day whether there was a rapid increase or decrees in humidity increases the incidence of stroke in all three years of research.Conclusion:Patients gender had no effect on the incidence of CVI. Seasons had no effect on the incidence of CVI. Most CVI in all three years of research was in relation to the old age and occurred in the older age group 70-79 (41.35%), where it was shown that the age of the patient influences the incidence of CVI. Extremely low relative humidity and extremely high, influence on the increase in the number of CVI. Determined is a slight correlation between the average relative humidity and CVI in single day.

<p>The dry subsidence regions of the tropics and subtropics play an important role in setting the Earth’s clear-sky climate sensitivity, as the clear-sky feedback in these regions is particularly sensitive to both the baseline relative humidity (RH) and small RH changes under warming. Therefore, it is crucial that climate models reliably simulate the RH and its response to warming in these regions. However, considerable inter-model differences in RH remain, also in global storm-resolving models, the newest generation of climate models with horizontal grid spacings sufficient to explicitly resolve deep convection. The goal of this study is to identify potential causes for these inter-model differences and understand the mechanisms behind it. For this we examine the effect of changes in different model parameters – including microphysical parameters and vertical grid spacing – on tropical free-tropospheric humidity in a global storm-resolving model, focusing on the dry subsidence regions. Back-trajectory calculations allow us to determine the characteristics of the last saturation points for dry tropical air masses as well as the magnitude of moisture sources and sinks during subsequent advection, and how both change in the sensitivity experiments. The trajectory analysis confirms that moisture gains and losses during advection play a secondary role in setting the RH distribution in tropical dry zones in the model, as suggested by earlier studies based on coarser models. This leaves changes in the points of last saturation, which are determined by the circulation and the temperature field, as the more likely driver of RH changes. Preliminary results from the sensitivity experiments indicate that particularly changes in the vertical grid spacing of the model can affect the RH in tropical subsidence regions. These RH changes are explained by changes in the temperature of the main outflow regions of deep convection in the upper troposphere, where most last saturation points are located. These results highlight the importance of circulation and temperature differences across global storm-resolving models in driving inter-model differences in RH.</p>

Effect of bamboo unit morphology on the preparation of bamboo fibers by steam explosion

This study employed bamboo as the raw material and employed the sodium chlorite method to remove most of the chromogenic groups in bamboo. The low-temperature reactive dyes were then utilized as the dyeing agents in combination with the one-bath method to dye the decolorized bamboo bundles. The dyed bamboo bundles were subsequently twisted into bamboo fiber bundles with high flexibility. The effects of various factors, including dye concentration, dyeing promoter concentration, and fixing agent concentration, on the dyeing properties, mechanical properties, and other properties of the twisted bamboo bundles were investigated using a tensile test, dyeing rate test, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results indicate that the macroscopic bamboo fibers prepared by the top-down method have excellent dyeability. The dyeing treatment not only improves the aesthetics of bamboo fibers but also improves their mechanical properties to a certain extent. When the concentration of dye is 1.0% (o.w.f.), the concentration of dye promoter is 30 g/L, and the concentration of color fixing agent is 10 g/L, the comprehensive mechanical properties of the dyed bamboo fiber bundles are the best. At this time, the tensile strength is 95.1 MPa, 2.45 times that of undyed bamboo fiber bundles. XPS analysis results show that the relative content of C-O-C in the fiber is significantly increased compared with that before dyeing, which indicates that the formed dye fiber covalent bond can strengthen the cross-linking between fibers, thus improving its tensile performance. The covalent bond is stable, and the dyed fiber bundle can retain its mechanical strength even after high temperature soaping.

Apple is an important fruit worldwide with nutrition and a huge market value. However, due to the mechanical damage during its handling after the harvest, millions of dollars are lost in the apple industry. Bruise (subcutaneous) is a mechanical damage caused to a fruit without any tearing of the fruit-skin. It could be caused by a mechanical impact, vibration, or compression which the fruit might come across during its handling after the harvest. It results in local degradation of the flesh tissue with browning effect with time. Normally, apple bruises take place beneath the peel and are difficult to detect by either visual or automatic color sorting. Thermal imaging offers a promising, contact-free, alternative technique for bruise detection in apples. Thermal imaging technique measures infrared energy emitted from the object surface which is converted into a thermal map called a thermogram. In the literature, there has been some work done on the influence of temperature and relative humidity of the surrounding on bruise susceptibility of fruits. In this paper, the influence of relative humidity in bruise development on apple was investigated applying thermal imaging technique. To accomplish this, two batches of healthy, almost same-sized, yellow and green apples with ten apples per batch were considered. The apples were subjected to a mechanical impact by dropping them from a constant height ensuring the fruit skin is not torn by the impact and the impact is same is for all the apples. Then, they were thermal imaged with the focus on their bruises. They were kept and observed at two different temperatures and relative humidity. The first set involved the relative humidity of 40–43% with room conditions whereas the second one involved the relative humidity of 80%–82% in the freezer compartment of a domestic refrigerator. For all the trials, the same condition was maintained for the fruits throughout the three-day observation. At the end of stipulated observation period, the fruits were thermal imaged to capture the bruise development for the different relative humidity levels for two different temperatures. The observation was repeated for three times to obtain the repeatability. The results show that the bruise development is faster for the higher relative humidity than for the lower one. This could be due to the lower transpiration rate of water from the fruits at higher relative humidity. Also, the water potential under the bruised skin decreases faster for lower relative humidity condition which results in decreased bruise development.

In order to investigate the influence of low relative humidity, we measured saccharin clearance time (SCT), frequency of blinking, heart rate (HR), blood pressure, hydration state of skin, transepidermal water loss (TEWL), recovery sebum level and skin temperature as physiological responses. We asked subjects to judge thermal, dryness and comfort sensations as subjective responses using a rating scale. Sixteen non-smoking healthy male students were selected. The pre-room conditions were maintained at an air temperature (Ta) of 25 degrees C and a relative humidity (RH) of 50%. The test room conditions were adjusted to provide a Ta of 25 degrees C and RH levels of 10%, 30% and 50%.RH had no effect on the activity of the sebaceous gland and on cardiovascular reactions like blood pressure and HR. However, it was obvious that low RH affects SCT, the dryness of the ocular mucosa and the stratum corneum of the skin and causes a decrease in mean skin temperature. Under 30% RH, the eyes and skin become dry, and under 10% RH the nasal mucous membrane becomes dry as well as the eyes and skin, and the mean skin temperature decreases. These findings suggested that to avoid dryness of the eyes and skin, it is necessary to maintain an RH greater than 30%, and to avoid dryness of the nasal mucous membrane, it is necessary to maintain an RH greater than 10%. Subjects felt cold immediately after a change in RH while they had only a slight perception of dryness at the change of humidity.

It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed to be higher with the cyclic flow (170 as MIF) than with the equivalent constant flow (170 l min(-1)). For 50 and 80% RH levels, the penetrations were usually greater with a constant flow (170 l min(-1)) than with a cyclic flow (170 l min(-1) as MIF). It is concluded that, for the tested electrostatic N95 filters, the change in penetration as a function of the loading time does not necessarily take place with the same rate under constant (MIF) and cyclic flow. Moreover, for all tested flow rates, the penetration is not only affected by the loading time but also by the RH level. Lower RH levels (10%) have decreasing penetration rates in terms of loading time, while higher RH levels (50 and 80%) have increasing penetration rates. Also, the loading of the filter is normally accompanied with a shift of MPPS towards larger sizes.

The predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) is currently used as an efficient biological control agent of thrips, whiteflies and spider mites, which are economically damaging pests of ornamental plants and vegetable crops grown in greenhouses and fields worldwide. Currently, the effects of relative humidity (RH) and water availability on the optimal growth of A. swirskii are unknown. Here, we test the combined effects of different levels of RH (33%, 53%, 73% and 92%) and water availability on the development and reproduction of male and female A. swirskii feeding on the dried fruit mite, Carpoglyphus lactis (Linnaeus). While eggs failed to hatch at 33% RH, the survival rates of the immature stages at ≥ 53% RH increased solely in response to water availability and not due to changes in RH. Regarding growth and development, low RH extended the egg–adult duration and pre-oviposition period. We also found that the negative effects of low RH on fecundity were partially or completely eliminated when drinking water was available. For the life table parameters, the highest values of net reproductive rate (R0) and intrinsic rate of natural increase (r) were achieved at the highest RH and when drinking water was available. Overall, water availability mitigated the negative effect of low RH on female reproduction, and female development was more sensitive to water availability than male development. Lastly, a comparison of similar research on A. swirskii suggested that water availability and RH are more influential on r than food source or temperature.