Constant Humidity Research Articles

Hygroscopic study of hydroxypropylcellulose : Structure and strain-induced birefringence of capillary bridges.

The hygroscopic method developed previously for studies of lyotropic liquid crystals is used for the first time in experiments with millimetric capillary bridges made of a hydroxypropylcellulose/water mixture. Composition of such very small samples is controlled via humidity of the surrounding air. By a slow and well-controlled drying of initially isotropic samples, the isotropic/anisotropic phase transition is crossed and polydomain pseudo-isotropic capillary bridges are prepared. Kept in an atmosphere of constant humidity, these bridges are stretched and the strain-induced birefringence [Formula: see text] n is measured as a function of the draw ratio [Formula: see text] . The variation of [Formula: see text] n with [Formula: see text] is interpreted in terms of an affine uniaxial deformation of the initial pseudo-isotropic texture.

Effects of phenolic hydroxyl and carboxyl groups on the concentration of different forms of water in brown coal and their dewatering energy

Oxygen functional groups as primary adsorption site of water are one of key factors controlling water re-adsorption and drying behaviors of brown coal. The dewatering energy of brown coal because of different oxygen functional groups is still unclear. Thus, two kinds of oxidized brown coal samples carrying more phenolic hydroxyl or carboxyl groups with similar pore structures were chosen. The concentrations of different water forms of the samples were determined from the moisture holding capacity at constant humidity and temperature and from the results of dewatering experiments analyzed by thermogravimetry coupled with differential scanning calorimetry. The results showed that the concentrations of three forms of water, i.e. free water, capillary water, and molecular water, showed good correlations with concentration of carboxyl groups. Comparison of 1H NMR analysis of dried and moisturized samples showed that the types of oxygen functional groups predominantly affected the water environment in coal. IR spectra of dried and adsorbed D2O samples showed that OH–π hydrogen bond due to carboxyl groups was easier broken than that due to phenolic hydroxyl groups. The water desorption energy of primary site and dewatering energy of samples with more carboxyl groups were lower than that of samples with more phenolic hydroxyl groups, because hydrogen bonding energy of water bonded to hydroxyl oxygen of carboxyl groups was lower than that of water bonded to hydroxyl oxygen of phenolic hydroxyl groups.

Wetting of hydrophobic substrates by pure surfactants at continuously increasing humidity

Spreading behavior of pure surfactants Triton X-100, Silwet L-77 and Zonyl FSO-100 on hydrophobic substrates was studied using a two-stage regime: (i) the first stage was a spreading at constant humidity (45%) until a quasi-equilibrium state was reached, and (ii) the second stage was a spreading at humidity increasing from 45% to almost saturation. During the first stage surfactants spread until reaching a quasi-equilibrium state, when the droplet diameter and the static advancing contact angle did not vary over time any more. The characteristic time of spreading during the first stage for L-77 and X-100 was a few seconds, whereas for FSO-100 it was tens of seconds. At the second stage, when humidity of the surrounding air was continuously increasing, the droplets of surfactants started to spread again. It was found that at this stage the spreading of all surfactants occurred only above a critical humidity ranged from 70 to 80%. Triton X-100 and Zonyl FSO-100 were found to be more sensitive to increasing humidity compared to Silwet L-77. It is shown that for all three pure surfactants used the radius on time dependencies obeyed a power law, with the power exponents close to either 0.1, which correspond to complete wetting or 0.25, which corresponds to Marangoni driven spreading. It was shown that water adsorption at the surfactant-vapor interface does not play a decisive role in initiation of the further spreading (except for Silwet L-77). Our findings suggested that spreading of surfactant droplets at the second stage was initiated predominantly by adsorption of water molecules from the surrounding air onto the solid substrate in front of the three-phase contract line.

Importance of Interface Diffusion and Climate in Defect Dominated Moisture Ultrabarrier Applications.

OLEDs and organic photovoltaic (OPV) devices require encapsulation from water vapor using a permeation barrier system. As a benchmark for barrier quality, often only a single number is provided as water vapor transmission rate. However, this value is highly dependent on the aging climate. So far, little scientific effort has been undertaken to characterize ultrahigh moisture barriers at different temperatures and relative humidities. We present Ca-test studies on sputtered Zinc-Tin-Oxide and atomic layer deposited AlOx barriers in extensively varied climates. Relative humidities are changed at constant temperatures, and temperatures are changed at constant absolute humidity. We find Henry's law to apply for sorption and discover a fundamental change of the diffusion regime with time related to the interface between the test and the barrier thin-film.

Characterization of Polymer Fiber Bragg Grating With Ultrafast Laser Micromachining

We report that the main photosensitive mechanism of poly(methyl methacrylate)-based optical fiber Bragg grating (POFBG) under ultraviolet laser micromachining is a complex process of both photodegradation and negative thermo-optic effect. We found experimentally the unique characteristics of Bragg resonance splitting and reunion during the laser micromachining process providing the evidence of photodegradation, while the mean refractive index change of POFBG was measured to be negative confirming further photodegradation of polymer fiber. The thermal-induced refractive index change of POFBG was also observed by recording the Bragg wavelength shift. Furthermore, the dynamic thermal response of the micromachined-POFBG was demonstrated under constant humidity, showing a linear and negative response of around −47.1 pm/°C.

Kinetic study on visible-light photocatalytic removal of formaldehyde from air over plasmonic Au/TiO2

Previously, the kinetic of UV photocatalytic oxidation (PCO) of formaldehyde in air over anatase TiO2 films was reported [Chem. Eng. J. 279 (2015) 897–903]. In the present work, the kinetic of visible-light (VL, λ>420nm) PCO of HCHO over plasmonic Au/TiO2 in a single-pass continuous-flow reactor is studied. The Au/TiO2 activated by oxygen plasma (OP) sample is selected for the kinetic study by comparing with the sample activated by calcination. The effects of light intensity, humidity and HCHO initial concentration on induction period and HCHO conversion are investigated. Subsequently, the VL light intensity- and humidity-dependent rate constant of the first-order reaction, k(I, H)VL, is expressed quantitatively as a function of I and H and accordingly the inherent rate constant kVL and humidity impact factor fH are deduced. In low light-intensity (I) regime, the exponent n of I equals 1 and kVL=0.05cm2s−1mW−1. In medium and high I regimes, n equals 0.36 and 0, kVL equals 1cm2s−1mW−1 and 7s−1, respectively. The humidity impact factors equal 11.0, −15.4 and −0.1 and quantitatively express the strongly positive, strongly negative and slightly negative net effects on the VL PCO rate in the low, medium and high humidity regimes, respectively.

Embryonic Callus Induction and Plant Regeneration of Lilium fargesii

In order to rationally protect and utilize the important wild traditional Chinese medicine resources,we built an efficient and instability regeneration system of Lilium fargesii Franch. by embryonic callus induction. With the scales as explants,by an orthogonal experiment,we studied the effect of different kinds and contents of plant hormone on embryonic callus induction and plantlet regeneration,and established a propagation system by tissue culture. The optimal medium for inducing embryonic callus was MS + 6-BA 0. 5 mg·L~(-1)+NAA 0. 5 mg · L~(-1)+ 2,4-D 0. 1 mg · L~(-1),the callus induction rate was 89. 29%,and the generation coefficient of bulblet was 4. 7. The optimal medium for regeneration of embryonic callus and inducing the bulblets was MS + 6-BA 1. 0 mg · L~(-1)+ 2,4-D 0. 1 mg · L~(-1),and its regeneration rate was 5. 0 /35 d. The optimal rooting medium was 1 /2MS + NAA 0. 2 mg·L~(-1),and the rooting rate was 100%. There were 90% of plantlet surviving after transplanting rooted plantlets into sand when cultured in constant temperature and humidity condition for 35 d. Our study could provide a basis on protecting the improved trait of wild resources of L. fargesii,and lay the foundation for expanding the artificial cultivation and embryoid asexual breeding.

Diastase and Invertase Activity Changes and 5‐Hydroxymethyl‐2‐Furfural Formation in Honeys Under Influence of Microwave Irradiation

AbstractThree types of honey including lime (Tilia spp.), buckwheat (Fagopyrum spp.) and acacia (Robinia pseudoacacia) honeys were analyzed. Honeys were subjected to conventional heating at a temperature of 60°C and heated in a microwave field. Depending on the type of honey, the temperature obtained in the microwaves was in the range of 48 and 69°C. After processing, honeys were stored for 3 months in uniform condition (ambient temperature, darkness, constant humidity) and subsequently reanalyzed. Oversized decrease in the value of diastase number was found in only two cases of honeys exposed to microwave field (after storage). Under the experiment conditions, there was no clear changes in the HMF concentration The largest increase was found in the case of acacia (A‐CD) and buckwheat (B‐B) honeys. For these types of honeys, increase in HMF concentration was of 2 mg/kg and 3 mg/kg, respectively. The biggest impact of the microwave irradiation was observed on the invertase activity. All the tested honeys, especially those subjected to microwave irradiation, showed a statistically significant decrease (five times the initial value) in the activity of this enzyme. Decrease in the diastase activity in microwaved honeys was from 6.8 to 3.7° Schade in case of acacia honey (A‐B) from 27.0 to 11.6°Schade in case of buckwheat (B‐OSP) honey.Practical ApplicationsThe research is valuable for preserving quality of natural products, i.e., honey. The use of thermal treatment of honey is particularly important in countries with tropical climates. This is due to the danger of spontaneous fermentation of honey. Thermal processing of honey is also used for other practical reasons (filling and packaging, preventing crystallization). From practical point of view, it is worth to point out that the use of microwave irradiation, despite advantages such as shorter heat exposure time appears to be unacceptable in the case of honey processing due to its destructive effect on the enzymes present in the product.

On-site calibration system for trace humidity sensors

A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensor-controlled heater. Mole fractions of water vapour between 1μmolmol−1 and 350μmolmol−1 (equivalent to frost-point temperatures from −76°C to −31°C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20°C to 60°C and kept stable within 0.1K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k=2) of the generated value.

Three-level experimental approach for creep and shrinkage of high-strength high-performance concrete

Most of the existing prediction models for creep and shrinkage are established based on the statistical regression analysis of test data drawn mostly from experiments performed on normal-strength concrete, and they might not be as applicable to high-strength high-performance concrete. The prediction precision can be improved by carrying out on the given concrete short-term creep and shrinkage measurements. A three-level experimental approach for creep and shrinkage is proposed in this study. Take the high-strength high-performance concrete used in the auxiliary shipping channel bridge of Sutong Bridge for example, the detailed three-level experimental process and results were presented. The specimens were grouped on three levels: “Material level”, “Component level” and “Structural level”. On the first level, plain concrete specimens were experimented in a constant temperature and constant humidity room. On the second level, creep and shrinkage of reinforced concrete specimens with different reinforcement ratio were experimented. On the third level, the long-term behavior of a segmental concrete cantilever beam, 12.8m long, under natural environment which was close to that of the actual bridge was studied. This experimental approach can provide a new train of thought to improve the predicted precision of the creep and shrinkage effects of the long-span concrete structures.

Correlation of Handheld Infrared Skin Thermometer and Infrared Videothermography Device for Measurement of Corneal Temperature.

In our study, we aimed to investigate the correlation of handheld infrared skin thermometer and videothermography device for the measurement of corneal temperature. Forty healthy individuals (80 eyes) were enrolled to the study. Participants underwent a detailed ophthalmologic examination and medical history review for excluding any ocular and systemic diseases. The measurements of the central corneal temperature were performed in a room having constant temperature, humidity, and brightness levels. To avoid any variability, all the temperature measurements were performed in the same examination room by a single examiner. The temperature was measured with a handheld infrared skin thermometer (MEDISANA, FTN) from the corneal surface. The same instrument was also used to measure the subjects' body temperature. Moreover, the subjects underwent the corneal temperature measurement by a noncontact videothermography device (Optris PI 450; Optris GmbH). The male to female ratio was 19:21 among the subjects. The mean age was 25.1±4.7 years. The mean body temperature was 36.93±0.33°C. The mean corneal temperatures measured by the handheld infrared skin thermometer and the ocular videothermography device were 36.94±0.28°C and 35.61±0.61°C, respectively (P<0.01). The mean temperature difference was 1.34±0.57°C, with a 95% confidence interval. There was a moderate correlation between the corneal temperatures measured by the 2 devices in the right, the left eyes, and both eyes, respectively (P=0.450, 0.539, 0.490). Handheld infrared skin thermometers can be used for the evaluation of the corneal temperature. These devices may provide a simple, practical, and cheaper way to detect the corneal temperature, and the widely performed corneal temperature measurements may afford us to understand the temperature variability in numerous ocular conditions in a better way.

Study of nitric oxide degradation properties of photoactive concrete containing nitrogen and/or carbon co‐modified titanium dioxide – preliminary findings

In recent years, titanium dioxide (TiO2) has been commonly applied in the production of photoactive concrete materials capable of degrading a wide range of air contaminant such as nitric oxide (NO), VOC etc. It was confirmed that the photocatalytic activity of TiO2 can be further enhanced by modifying the photocatalyst with non-metals such as nitrogen (N) or carbon (C). In view of this finding, several concrete/TiO2 composites consisting of commercial concrete and raw anatase TiO2 (supplied by Grupa Azoty Zaklady Chemiczne ‘POLICE’ S.A., Poland), previously modified with ammonia [N source] and/or 2-propanol [C source] have been manufactured. For reference, the additional concrete samples were prepared, containing unmodified TiO2 and commercial titania P25 (Evonik). The NO degradation properties of prepared photoactive concrete materials were evaluated using laboratory test set-up. The measurements were conducted under constant temperature and humidity conditions, using ultraviolet light irradiation. Significant NO removal was recorded for the TiO2/concrete composites containing N and/or C co-modified titania. The results were related to the improved photocatalytic activity of modified photocatalysts and probable, partial NO reduction to N2, via the selective catalytic reduction process catalysed by TiO2.

Integrity of CFRP-concrete bond subjected to long-term cyclic temperature and mechanical stress

This paper reports on the long-term performance of CFRP strengthened concrete members subjected to 20–50°C cyclic temperature, 60% constant humidity and sustained loading. The induced sustained stress was imposed through a range of loading values from 0% to 35% of the ultimate strength of specimens subjected to normal environmental conditions. The behaviour of CFRP/concrete lap shear specimens prepared using two types of commercially available two-part epoxy adhesives was investigated. Three different curing conditions were taken into account.

Influence of aluminum phosphate contaminant on discharge characteristics of suspension glass insulators

Contaminant composition affects the discharge characteristics of external insulation. This paper studies the intense discharge phenomenon at low relative humidity (77%) in an AC 500 kV substation in Southern China. Due to farming and the soil feature in the sugar cane field around the substation, aluminum phosphate is formed in the soil, and accumulates on the external insulation surface owing to blowing dust. The porous structure and four-coordinated aluminum atom lead to strong moisture absorption capacity of aluminum phosphate. Then electrical performances of aluminum phosphate as a contaminant on insulation surface were investigated by means of discharge test in a constant humidity chamber. The experimental results show that, compared to conventional contaminant, aluminum phosphate contamination insulator has lower discharge inception voltage and stronger discharge intensity when relative humidity is above 70% and the aluminum phosphate content exceeds 20% in the non-soluble deposit. Aluminum phosphate is the main cause for the discharge phenomenon in the substation under study. It needs to be considered for insulation design and maintenance in ferralsol areas where phosphate fertilizer is heavily used. The moisture absorption of contaminant merits special consideration for further research.

Verifying the operation of an elastic crossbar system applied to a panel painting: the Deposition from the Cross by an anonymous artist from Abruzzo, sixteenth century

This study deals with the post-treatment evaluation of the elastic crossbar system already designed and installed on the recently restored panel painting Deposition from the Cross by an anonymous artist from Abruzzo (sixteenth century). After the restoration, the panel and the crossbars were subjected to mechanical tests to identify their elastic characteristics. Then the panel, equipped with the elastic crossbar system, was subjected for about two months to controlled environmental cycles made up of approximately constant humidity periods. During the two months, the forces exerted by the springs and the deformations of both panel and crossbars were continuously monitored. A mathematical model, calibrated on the specific parameters derived from the analysis of the panel, provided the deformation that the panel would have shown without the crossbars; comparing the model output with the measured data provided a restraining effect (RE) of approximately 7% (RE could range between zero – no restraint – and 100% – total restraint). Future developments of this project will define appropriate procedures to design an elastic crossbar system for a given panel, once the expert judgement of restorers has identified the most desirable RE to be achieved.

Temperature-dependent development of the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) on tomato plant Lycopersicon esculentum Mill. (Solanaceae)

Laboratory studies on the temperature-dependent development of Tuta absoluta were performed at 10 constant temperatures ranging as from 15 to 34 ± 1°C. The duration of total development was measured for every temperature. Tayfun F1 tomato variety was used for larval feeding ve all experiments were done at climatic cabinets where had long daylight period (16:8) and 65% ± 5 constant humidity conditions for every temperature. According to obtained data, developmental zero () and thermal constant () were calculated by using linear regression and lower (), optimum () and upper () temperature thresholds for total developmental period of pest were calculated by using Polynomial ( 4 th ), Logan 6, Logan 10, Lactin 1, Briere 1 nonlinear regresyon models. Development time decreased with increasing temperature within the range 15-29 °C ranging from 78.17 days to 21.39 days. Zero developmental threshold for total development of Tuta absoluta was estimated as 8.94 °C and thermal constant was found as 419.46 degree-days. And lower, optimum and upper temperature requests were estimated with different models and results ranging from 8.9-12.5, 31.00-31.07 and 35.9-38.5, respectively.

Measurement of the Temperature and Pressure Characteristics of the Car Seats - Relationship between Humans&lt;sup&gt;&lt;/sup&gt;

Research of the correlation of the biomechanical characteristic of a sitting human and car seat is based on measurements of several basic parameters, such as value of the area contact pressure, map of contact temperature, contact humidity, etc. So obtained map of surface each parameter which we can compare at a same time and so we can identify correlations between these parameters and biomechanical properties of human, e.g. human anatomy, the body forms, age, sex physique etc. Based on these analyzes is possible to optimize the levels of this parameters for obtaining the ideal seating comfort. The correlation between fatigue for the driver and sitting comfort is described in many publications dealing with this theme. However, a repeatability real experiment in a car is questionable [1]. It is therefore preferable to perform these measurements in the laboratory and simulate the same conditions as in moving car at a constant ambient temperature and humidity, with the same test persons. The most suitable is the use in the measurement of different types of car seats and various human.

The Use of Forensic Entomology in Legal Veterinary Medicine: A Case Study in the North of Italy

During winter 2010 a forensic entomological study was undertaken in San Bartolomeo in Bosco (FE) Emilia-Romagna Region (North of Italy) on different animal carrion found in a farm several days after they died. The entomological evidence collected at the scene consisted of Calliphoridae (larvae of Calliphora vicina), Stratiomydae (larvae of Hermetia illucens), Dermestidae (larval exuviae of Dermestes maculatus). During diagnostic investigation the Diptera Larvae were taken from the carrion and were reared in the laboratory under constant temperature, humidity and fotoperiod. The minimum Post Mortem Interval (mPMI) was calculated using the quantity of thermal energy necessary for a given species to complete its life cycle from eggs to imago (accumulated degree-days-method). The results of the calculations were consistent with what the judicial investigation later showed. This case report illustrated the importance of using insects in legal veterinary medicine for define the time and circumstances of the death of an animal.

Migration of sodium chloride in dry porous materials

Groundwater can saturate soil above the water table within the capillary fringe associated with the pore size of the parent soil. External evaporation has been viewed as a mechanism for enhancing upward flow, potentially creating problems of salt heave beneath roads and foundations if the groundwater is saline, analogous to concerns with efflorescence in masonry. The role of internal evaporation in promoting crystallization, and especially in altering the transport process of the pore fluid, has been recognized but is only partially understood. The purpose of this paper is to examine evidence for the upward percolation of brine accompanying salt crystallization inside a porous granular material. A series of experiments are described using vertical flow columns packed with dry sand above a reservoir of saline fluid, to explore whether salt transport could take place by autogenous wicking above the initial capillary fringe. The conditions inside the columns were monitored at specific elevations with sensors measuring bulk electrical conductivity, dielectric constant and relative humidity. Dendritic salt crystallization was observed inside the sand, accompanying surface heave. Ultimately, efflorescence on the surface led to the formation of a salt crust. Some implications for the potential damage to roads and foundations in arid regions, and to masonry subject to rising damp, are discussed.

Piezoresistive Silicon Cantilever Covered by ZnO Nanorods for Humidity Sensing

Gravimetric humidity sensing performance is described with piezoresistive silicon cantilevers covered by ZnO nanorods in a low-cost wet chemical deposition process. High sensitivity at small hysteresis between increasing and decreasing humidity loading is observed as well as a good temporal stability at constant humidity and temperature. Due to ease of interfacing with electronics and low-power operation promoted by resonant devices, we expect that the developed sensors will be highly attractive for wearable environmental monitoring applications.