Moisture Problem Research Articles

Moisture and Hydrogen Release in Optoelectronic Hermetic Packages

In this work we investigated the effect of Nickel (Ni) plating process on the Hydrogen (H) and moisture content of hermetic packages such as those used in optoelectronics. The work offers an explanation of moisture formation inside hermetic packages by showing that the problem arises from the electroless plating of Ni which is found to be inherently rich in H. The effects of the Ni plating process, baking, and Au thickness on the moisture and hydrogen content of hermetic packages were thoroughly explored. It was observed that baking the package components before sealing alleviates the problem of moisture formation inside the package but it doesn't fully eliminate it. It was only after changing the Ni plating process from electroless to electrolytic that the moisture problem actually disappeared. Our investigation showed that moisture formation inside hermetic packages is due to H evolution from the electroless Ni which eventually reacts with surface oxides to form H2O. SIMS analysis of electroless and electrolytic Ni showed that electroless Ni is around ten folds richer in H compared to its electrolytic counterpart. SIMS analysis also showed that H content in electroless Ni can be significantly reduced with heat treatment.

Analysis on Built Environment in Underground Shopping Malls in Chongqing in P.R. China

To identify current situation of built environment in underground shopping malls, the study based on both field test and questionnaire investigation was carried out in underground shopping mall A and B in Chongqing in P.R. China. It analyzed the current situation of indoor thermal environment, light environment, sound environment as well as air quality. It found that the most prominent issue was indoor ventilation, and then air quality, thermal comfort and noise sequentially. Light and moisture problem was easy to be overlooked. Based on the current issues, it puts forward several measures to improve the built environment of underground shopping malls in this study.

Discuss on the Air Curtain Dehumidification Technology Program of Underground Engineering

To solve the moisture problem at the hallway near the protective door of the underground engineering, an air curtain dehumidification technology program has been proposed and discussed. For the moist air from the protective door, the air curtain dehumidifier can be used to control its flow direction: all moist air will directly enter the inlet of the dehumidifier by the action of negative pressure gradient without any ventilation duct. The main technical features of the program are that, the air curtain dehumidifier should be installed at the corner of the ground or hanged on the wall beside the inner side of the protective door, which inlet and outlet should be collocated in the level and along the long direction of the underground engineering; the dehumidifier rotating speed should be controlled by the humidity and the inflow speed of the fresh air. Preliminary studies indicates that this technical solution is feasible, but still there are a lot of details that need to be studied in follow-up research process.

Risk Aversion Behavior of Farm Households and the Role of Credit Service in Kobbo District, North Wollo Zone of Ethiopia

Risk and uncertainty in agricultural production is one of the factors that hinder efficient allocation of resources and investment decision under smallholder production system. This study was carried out with the objectives of examining the various sources of risk and management strategies of farm households in Kobbo district in two different agro-ecologies and examining possible risk-return trade off associated with various levels of risk aversion parameters for credit user and nonuser small framers. The study used the data collected from randomly selected 116 sample farmers during the 2004/05 production year. The descriptive statistics results showed that among the possible sources of risk identified by farmers, rainfall variability and livestock feed shortage problems were considered the first problem in their priority setting by a large proportion of framer. Though the number of farmer are few, weed infestation, pest incidence, crop disease, shortage of oxen (due to disease and death), price variability were also considered as most important sources of risk by the framers. Farmers adapt different management strategies to over come the impact of risk. This includes, planting early maturing crops, and small-scale irrigation, petty trading and labour selling (daily labour). In addition, to protect insect and pest attacks of crops, farmers used mainly traditional pest control measures and to some extent insecticides and pesticides chemicals. On the other hand, replanting (replacing), using own family labour and supports from relative and friends (social networking) were the strategies farmers used to protect weed infestation problems in the study area. Similarly, farmers practice maintaining leftover straw and crop residue, move their livestock to other areas and selling of animals to minimize feed shortage problem. Mean-variance (E, V) analysis using negative exponential utility function has been chosen as an appropriate methodological tool and used to determine the optimal production plan of the farmers under income risk. The results of the model indicated that farmers in the midland area are less risk averse as compared to farmers in the lowlands with a risk aversion parameter value (λ) of 0.00338 and 0.010, respectively. This indicates that farmers in the midland area are less risk averse than farmers in the lowland areas. On the other hand, the results indicate that credit user farmers are less risk averse in the lowland as compared to the nonuser farmers whereas credit user farmers are more risk averse than the nonusers in the midland area of the district. The risk aversion parameter of credit users is found to be 0.0075 and 0.001 in the midland and in the lowland, respectively. Similarly, the risk aversion parameter of non-credit users is 0.00455 and 0.040 in the midland and in the lowland areas, respectively. The result of this study also revealed that risk-bearing ability of farmers in different agro-ecologies is different, entailing area specific development programs based on the attitude of the farmers to ensure food security status of farm households in the region in general and in the study area in particular. The study has also shown that among the crops grown in the area, sorghum has an income risk stabilizing effect and less risky in the midland area of the district whereas teff and maize have contributed to stabilizing income risk in the lowland. On the other hand, in the midlands of the district teff and lentil are not optimally used under the farmers’ condition. Wheat and barley also contribute to income risk of the household. Livestock production in general was found to be optimal and showed income risk stabilizing effect to the farm households. One of the critical problems contributing to higher risk aversion values of lowland farmers in the district is moisture stress problem. In xviii this regard, regional and national research institutions should focus on drought tolerant crop varieties which stabilize the level of income of the farmers in the study area in particular and other moisture stress area in general. In addition, livestock production was found to play income risk stabilizing. Thus, research and extension activities that are geared to promotion of highly productive livestock technologies would have high chance of being accepted by the farmers. Non/off-farm activities show stabilizing effect to the total household income more importantly, in lowland areas where there are better communication network and marketing facilities. Thus, developing such type of infrastructure facilities promotes non-farming activities whereby farmers can supplement and stabilize their household income. Lastly, credit service was found to stabilize income in the lowland areas where farmers have access to marketing services and increases income risk in the midland where market and alternative income generating activities are lacking showing that credit service should be integrated with other rural development services to make use of it in most productive way.

Efficacy of Occupant-Collected Dust Samples in the Evaluation of Residential Allergen and Fungal Levels

This study evaluated the ability of a resident to evaluate their home for allergens and mold using a settled dust test kit compared with evaluation and collection of settled dust by an industrial hygienist. Forty-three home residents were provided with a kit containing written instructions and a vacuum cleaner attachment for collecting a settled dust sample. Within 2 weeks of receiving the occupant-collected sample, an industrial hygienist evaluated these homes, including a visual inspection, collection of settled dust, and collection of spore trap samples. Settled dust samples were analyzed for major dog, cat, dust mite, and cockroach allergens using immunoassay methods, and for mold spore equivalents using quantitative polymerase chain reaction methods for the 13 mold species or species groups comprising the American Relative Moldiness Index (ARMI). Allergen concentrations and ARMIs were compared between the resident- and industrial hygienist-collected samples. Linear regression between the two sets of samples showed strong correlations for dog allergen (r2 = 0.92) and cat allergen (r2 = 0.90). Correlations for dust mite (r2 = 0.57) and cockroach allergens (r2 = 0.22) were lower, likely due to most samples being near the limit of detection. ARMIs were highly correlated (r2 = 0.68) and were in categorical (high, medium, or low) agreement for 76% of residences. These results show that residents can reliably follow directions and collect settled dust samples, providing an efficient method to remotely screen homes for elevated allergen levels and to identify homes with a potential mold or moisture problem that may need further evaluation.

Indirect performance comparison for styrene–butadiene–styrene polymer and fatty amine anti-strip modified asphalt mixtures

Rutting and moisture damage are two important distress mechanisms for asphalt mixtures. The aim of this study is to analyze effects of SBS polymer and fatty amine anti-stripping agent additives for asphalt mixtures. Indirect performance comparison was evaluated with such additives. SBS and amine agents were compared with indirect effects in context with deformation and moisture resistance. Three types of moisture conditioning were selected. Regimes were based on water immersion, freeze–thaw cycles and superposition of these. Repeated creep tests (RCTs) and indirect tensile (ITT) tests were applied. In view of RCT polymer showed higher resistance to rutting based on permanent deformations than the control and amine modified mixtures. Lower deformations were calculated with SBS than the others according to the RCT. For high temperature and combined moisture effects based on water saturation and freeze–thaw cycle rutting and moisture problem have been being a serious problem for both control and SBS-anti stripping agent modified mixtures. In this context great importance must be given in design and quality control. Proportional moisture damage evaluation was found as a confliction. With the increasing of rise period lower resilient modulus (RM) were obtained with all control and modified mixtures in ITT. Selected moisture conditioning methods reveal observable level of damage with the RM test (ASTM D4123) with the selected parameters. Both amine and SBS modified mixtures gives higher RM hence load spreading capacity increases with both SBS and anti-strips.

Common Mould Related Health Problems Associated with People Living in Houses with Moisture Problem

Common Mould Related Health Problems Associated with People Living in Houses with Moisture Problem

Prevalence of Mould Found in Buildings with Moisture Problem in Port Harcourt, River State of Nigeria

Prevalence of Mould Found in Buildings with Moisture Problem in Port Harcourt, River State of Nigeria

Dampness in dorm rooms and its associations with allergy and airways infections among college students in China: a cross-sectional study

A cross-sectional study was carried out at Tianjin University campus, China, from February 21 to June 10, 2006, to survey the association between dampness in dorms, and allergy and airways infections among college students. The health and dampness conditions were self-reported by 3436 students living in 1511 dorm rooms located in 13 buildings on the campus. The buildings were selected according to their positions, construction periods and occupant densities. The symptoms involved wheezing, dry cough during night, rhinitis, eczema, cold/flu, ear inflammation, pneumonia and tuberculosis. The indoor moisture signs were mould/damp spots on walls, ceilings and floors; suspected or ever happened water damage; condensation on windowpane in winter and odours perceived by subjects themselves. There was a significant positive association between condensation and dry cough. Eczema was often reported in rooms with moisture problem. Dampness was a significant risk factor for common cold. Dampness problems in dorms of Chinese students are a risk factor for allergic symptoms, and hence there is a need for dorm environment improvement. Health problems related to ventilation and microbiology problems in dorms should be further studied.

Low home ventilation rate in combination with moldy odor from the building structure increase the risk for allergic symptoms in children

There are consistent findings on associations between asthma and allergy symptoms and residential mold and moisture. However, definitions of 'dampness' in studies are diverse because of differences in climate and building construction. Few studies have estimated mold problems inside the building structure by odor assessments. In a nested case-control study of 400 Swedish children, observations and measurements were performed in their homes by inspectors, and the children were examined by physicians for diagnoses of asthma, eczema, and rhinitis. In conclusion, we found an association between moldy odor along the skirting board and allergic symptoms among children, mainly rhinitis. No associations with any of the allergic symptoms were found for discoloured stains, 'floor dampness' or a general mold odor in the room. A moldy odor along the skirting board can be a proxy for hidden moisture problem inside the outer wall construction or in the foundation construction. There are indications that such dampness problems increase the risk for sensitization but the interpretation of data in respect of sensitization is difficult as about 80% of the children with rhinitis were sensitized. Furthermore, low ventilation rate in combination with moldy odor along the skirting board further increased the risk for three out of four studied outcomes, indicating that the ventilation rate is an effect modifier for indoor pollutants. This study showed that mold odor at the skirting board level is strongly associated with allergic symptoms among children. Such odor at that specific place can be seen as a proxy for some kind of hidden moisture or mold problem in the building structure, such as the foundation or wooden ground beam. In houses with odor along the skirting board, dismantling of the structure is required for an investigation of possible moisture damage, measurements, and choice of actions. In homes with low ventilation in combination with mold odor along the skirting board, there was even a higher risk of health effects. This emphasizes the need for the appropriate remediation as this is an ever increasing problem in poorly ventilated houses that are damp.

Dampness at dorm and its associations with allergy and airways infection among college students in China: a cross-sectional study

A cross-sectional study was carried out at Tianjin University campus, China, from February 21 to June10, 2006, to survey the association between dampness in dorms and allergy and airways infection among college students. The health and dampness condition were self-reported by 3436 students living in 1511 dorm rooms located in 13 buildings on the campus. The buildings were selected according to their positions, construction periods and occupant densities. The allergy and airways infection symptoms involved wheezing, dry cough during night, rhinitis, eczema, cold/flu, ear inflammation, pneumonia and tuberculosis. The indoor moisture signs were mould/damp spots on walls, ceilings and floors; suspected or ever happened water damage; condensation on windowpane in winter and odours perceived by subjects themselves. This study showed there was significantly positive association between condensation and dry cough. Eczema was often reported in rooms with suspected moisture problem. Dampness was a significantly risk factor for common cold. This paper indicated that dampness problem at dorms of Chinese students was a risk factor in irritating allergic symptoms, and hence there is a need for dorm environment improvement. The ventilation and microbiology problems in dorm environment corresponding to dampness should be further studied, especially when it is associated to occupants' health.

Analysis of coupled heat and moisture transfer in masonry structures

Evaluation of effective or macroscopic coefficients of thermal conductivity under coupled heat and moisture transfer is presented. The paper first gives a detailed summary on the solution of a simple steady state heat conduction problem with an emphasis on various types of boundary conditions applied to the representative volume element—a periodic unit cell. Since the results essentially suggest no superiority of any type of boundary conditions, the paper proceeds with the coupled nonlinear heat and moisture problem subjecting the selected representative volume element to the prescribed macroscopically uniform heat flux. This allows for a direct use of the academic or commercially available codes. Here, the presented results are derived with the help of the SIFEL (More information available at http://mech.fsv.cvut.cz/web/?page=software) (SImple Finite Elements) system.

THE RELATIONSHIP BETWEEN WATER CONTENT AND DECAY OF VARIOUS WOODS UNDER HYGROTHERMAL STEADY STATE

There are two points of view for the prevention design of moisture problem in the building insulated envelope. One is the strictly prevention of high moisture condition in the insulated wall cavity. The other one is the permission of short-term high moisture condition, condensation and high moisture content of the wooden material as long as keeping physical durability. If the later standpoint were chosen, the insulated envelope design of every variety for Japan would be possible. Nevertheless, there are no criteria to estimate the damage of physical durability of wood by the biological factors related high moisture condition. The points of this paper are as follows; 1) The importance of estimation damage of woods by the moisture problems is describes. 2) 2 case of hygrothermal steady state experiments were done to get basic acknowledge of woods damage by biological factors considering term, water content, temperature and humidity, physical durability.

Exposure to Mites, Sensitisation and Allergy to Mites in Moisture Damaged Buildings

We assessed the mite exposure of patients in the Skin and Allergy Hospital by collecting samples of settled dust from their workplaces and homes. Mites were counted and identified microscopically. Mites were found in 26% of the samples. Three samples (3%) contained more than 100 mites per gram dust and another sample (1%) had more than 500 mites per gram dust, the suggested limits for mite sensitisation and at which acute allergic symptoms can be expected, respectively. Mites were a more common finding from water damaged houses and workplaces with visible mould but they also existed in large numbers in buildings with no reported indoor air quality problems. Dust mites ( Pyroglyphidae) were the most abundant species. However, storage mites were also frequently found. Patients reported a high prevalence of respiratory symptoms, especially nose and eye irritation which may partly be due to sensitisation especially to storage mites. Although mites are commonly found in workplaces and homes they are seldom present in high concentrations. Mite sensitisation and especially a positive reaction to storage mites in skin prick tests may be an indication of a moisture problem in the domestic or work environments.

Linking Adhesive and Structural Proteins in the Attachment Plaque of Mytilus californianus

The byssal attachment of California mussels Mytilus californianus provides secure adhesion in the presence of moisture, a feat that still eludes most synthetic polymers. Matrix-assisted laser desorption ionization mass spectrometry was used to probe the footprints of byssal attachment plaques on glass cover slips for adhesive proteins. Besides the abundant mcfp-3 protein family (Zhao, H., Robertson, N. B., Jewhurst, S. A., and Waite, J. H. (2006) J. Biol. Chem. 281, 11090-11096), two new proteins, mcfp-5 and mcfp-6, with masses of 8.9 kDa and 11.6 kDa, respectively, were identified in footprints, partially characterized and completely sequenced from a cDNA library. mcfp-5 resembles mcfp-3 in its basic pI and abundant 3,4-dihydroxyphenyl-L-alanine (Dopa; 30 mol %), but is distinct in two respects: it is more homogeneous in primary sequence and is polyphosphorylated. mcfp-6 is basic and contains a small amount of Dopa (<5 mol %). In contrast to mcfp-3 and -5, tyrosine prevails at 20 mol %, and cysteine is present at 11 mol %, one-third of which remains thiolate. Given the oxidative instability of Dopa and cysteine at pH 8.2 (seawater), we tested the hypothesis that thiols serve to scavenge dopaquinones by adduct formation. Plaque footprints were hydrolyzed and screened for cysteine dopaquinone adducts using phenylboronate affinity chromatography. 5-S-Cysteinyldopa was detected at nearly 1 mol %. The results suggest that mcfp-6 may provide a cohesive link between the surface-coupling Dopa-rich proteins and the bulk of the plaque proteins.

Comparative Analysis of Response-factor and Finite-volume based Methods for predicting Heat and Moisture Transfer through Porous Building Materials

Many of the now well-known building energy simulation programs use the response factor method developed in the early 1970s by Stephenson and Mitalas. These are TRNSYS, EnergyPlus, Blast, and DOE-2, to name but a few. Others, such as PowerDomus, ESP-r, and BSim, perform finite-volume or finite-difference calculations to solve the heat and mass transfer through the building envelope. These two different approaches are known to have strengths and weaknesses. The main objective of the present exercise is to compare the prediction of both methods. A two-step procedure is employed here. The first deals with the pure thermal problem, i.e., without moisture calculation. Three different cases of increasing complexity are studied and compared to analytical solutions. The second step focuses on the moisture problem alone by comparing the responses obtained with a two-layer buffer storage model and a finite-volume discretization for moisture transfer. Results show that time step values are determinant even for pure thermal cases where the classical value of 1 h can lead to notable errors. For problems with moisture sorption in the wall, it has been shown that grid refinement is a very decisive parameter, while the time step has to be set, to unusually small values, to achieve a good response.

Linear constitutive model for mechano-sorptive creep in paper

The creep of paper is accelerated by moisture cycling. This effect is known as mechano-sorptive creep. It is assumed that this is an effect of transient stresses produced during moisture content changes in combination with non-linear creep behaviour of the fibres. The stresses produced by the moisture content changes are often much larger than the applied mechanical loads. If this is the case, the mechanical loads are only a perturbation to the internal stress state, and it will appear as if the mechano-sorptive creep is linear in stress. It is possible to take advantage of this feature. In the present report the pure moisture problem is first solved. The mechanical load is then treated as a perturbation of the solution to the moisture problem. Using this strategy, it is possible to linearize a non-linear network model for mechano-sorptive creep and to formulate a continuum model. As a result, the number of variables in the model is reduced. This is a significant improvement as it will be possible to use the linearized model to describe the material in a finite element program and solve problems with complicated geometries.

Investigations into the role of activated carbon in a moisture-blocking cement formulation

Physical deterioration is a natural consequence of moisture attack in finished concrete. Moisture is retained in open voids in prepared cement during mixing and hydration stages. Further atmospheric moisture uptake occurs following dehydration under use conditions in polymer-containing cement formulations, since polymers act as conduits for moisture ingress. The initial attribute of added strength from the polymer in improved cement formulations is thus nullified. Customary solution to the moisture problem has centered around improving moisture resistance by significant reduction of inherent macro defects. A more complete method of moisture blocking by the reaction of activated carbon with a vinyl polymer included in the cement formulation is described here. The moisture blocking action is due to the mitigation of open voids by the occlusion of a carbon-vinyl additive, essentially resulting in filled voids or no voids in the prepared cement, producing a durable finished concrete product. Supporting evidence for the above by thermal, polarization, X-ray and SEM are reported in this paper.

Genotoxicity of gliotoxin, a secondary metabolite of Aspergillus fumigatus, in a battery of short-term test systems

The genotoxic effects of gliotoxin, a known fungal secondary metabolite, were studied. Gliotoxin was purified from cultivation medium of Aspergillus fumigatus isolated from the indoor air of a moisture problem house. The genotoxicity of gliotoxin was assessed both in bacterial test systems including bacterial repair assay, Ames Salmonella assay and SOS-chromotest, and in mammalian cells using single cell gel (SCG) electrophoresis assay and sister-chromatid exchange (SCE) test. Gliotoxin was found to be genotoxic in the bacterial repair assay but, not in the Salmonella test or SOS-chromotest. A dose-related increase in DNA damage was observed in mouse RAW264.7 macrophages exposed to gliotoxin for 2 h in plain medium in the SCG assay. In contrast to the positive response in the SCG assay, gliotoxin did not induce any clear, dose-related increase in SCEs in Chinese hamster ovary (CHO) cells.

Immunoglobulin G antibodies to moulds in school-children from moisture problem schools.

The purpose of the present study was to evaluate mould-specific immunoglobulin G (IgG) antibodies in children exposed to moisture and mould problems in their school, and the association between IgG antibodies and mould allergy, active or passive smoking and respiratory symptoms. IgG antibodies were studied to 24 moulds in 93 children from three moisture problem schools and in 33 children from a reference school. The antibodies were measured by enzyme-linked immunosorbent assay and compared to positive adult sera. There were no significant differences in mould-specific IgG concentrations between exposed and non-exposed school-children. Antibodies to moulds common in moisture damaged buildings were associated with allergic diseases, as well as with mould-specific immunoglobulin E (IgE) or skin prick test (SPT) findings. Aspergillus fumigatus and A. versicolor were the moulds with the most consistent findings. Active and passive smoking were associated with low levels of antibodies to many moulds. Though the association between asthma, wheezing or cough symptoms, and IgG to moulds was not significant, 7 (39%) of the 18 children with multiple (> 7) elevated IgG findings suffered from asthma or wheezing. Allergy was, but asthma was not, associated with IgG antibodies to the moulds that can be found in moisture damaged buildings. However, no association was found between IgG antibodies to moulds and exposure to moisture and moulds in school.