British Library Electronic Table of Contents (United Kingdom)

Contents The study aimed at testing the effectiveness of dimethylformamide, alone or combined with glycerol, as cryoprotectant for freezing ram semen. Ejaculates from nine rams were cryopreserved in Tris-based extenders, containing 5% of glycerol, association of dimethylformamide with glycerol, in four proportions achieving 5% of cryoprotectors in the media and pure dimethylformamide (2, 3, 4 and 5%) in replacement to glycerol. The samples were diluted to 100--106 sptz/ml and stored in 0.25-ml straws in liquid nitrogen. After thawing (37C for 30-s), motility was preserved better by the extender containing 5% of glycerol (p-<-0.05). The extenders containing pure dimethylformamide, or more than 2% in combination with glycerol, provided sperm motilities close to zero. Plasma and acrosomal mem...

Energy Technology Data Exchange (ETDEWEB)

The marine ram-type blowout preventer deployed from an offshore drilling rig has one serious disadvantage, its inaccessibility. A development to promote reliability of the subsea ram-type preventer and reduce the excess running and pulling to charge out rams, is the variable bare ram (VBR). Unlike the standard ram, the VBR has the ability to pack off a range of pipe sizes. Interest in VBR's has been revived and research and development in this equipment goes on at each of three manufacturer's facilities in Houston.

International Nuclear Information System (INIS)

On-power refuelling is an integral feature of PHWR units. The most notable aspect of refuelling system of 540 MWe PHWR (TAPP-3 and 4) is that the FM Head is based on rack and pinion mechanism for B-ram and C-ram of Ram assembly. Latch ram used during plug operations, is assembled in between B-ram and C-ram and is moved by a ballscrew driven by oil hydraulic motors. This unique design has been employed for the first time in a PHWR unit. In comparison, B-ram is ballscrew driven and C-ram is moved by heavy water hydraulic force in FM Heads of 220 MWe PHWR units. Over the years, a number of design improvements have been carried out in the 220 MWe Fuelling Machines to meet the challenge of increasing demands of higher refuelling rates. However, in 540 MWe unit, the average refuelling rate for an equilibrium core is nearly ...

British Library Electronic Table of Contents (United Kingdom)

Abstract Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram- and suction-feeding sharks using computed tomography. The results indicate that suction-feeding sharks have ceratohyal cartilages with a larger second moment of area than ram-feeding sharks. The result also indicates that the ram-suction index, which is an indicator of relative contribution of ram and suction behavi...

British Library Electronic Table of Contents (United Kingdom)

A few studies have found poor semen quality in sons whose mothers have received fertility treatment, but it is unknown whether the poor semen quality is related to the infertility treatment or to infertility per se, for example, whether it is caused by hereditable factors. Using data from a population-based, Danish follow-up study conducted in 2005-2006, the authors of the present study examined whether sons of subfertile couples who had not received fertility treatment had poorer semen quality than sons of fertile couples. Among the 311 participants, an inverse association between parental waiting time to pregnancy and both semen volume and total sperm count was observed (p trend = 0.04 and p trend = 0.046, respectively). Semen volume in sons of subfertile parents (pregnant after ?1 ye...

UK PubMed Central (United Kingdom)

BackgroundEvidence on human semen quality as it relates to exposure to various metals, both essential (e.g., zinc, copper) and nonessential (e.g., cadmium, lead), is inconsistent....Full Text Available

UK PubMed Central (United Kingdom)

Male reproductive proteins (MRPs), associated with sperm and semen, are the moieties responsible for carrying male genes into the next generation. Evolutionary biologists have focused on their...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

ObjectivesVaricocele is a common cause of infertility, and varicocele-associated testicular hypotrophy has been described as a potential cause of decreased semen quality. We investigated the relationship between testicular hypotrophy and poor semen quality in infertile men with varicoceles. We hypothesized that bilateral hypotrophy is required before the semen quality is severely impaired.MethodsWe retrospectively identified consecutive patients with palpable varicoceles undergoing an infertility evaluation at a single academic center. Each patient was evaluated by the same clinician with history and physical examination. Testicular hypotrophy was defined as a size discrepancy of greater than 3 mL or an absolute size of less than 14 mL. Multivariate logistic regression analysis was used to...

UK PubMed Central (United Kingdom)

BackgroundThe association between infertility and sperm disomy is well documented. Results vary but most report that men with severely compromised semen parameters have a significantly...Full Text Available

Science.gov (United States)

A few studies have found poor semen quality in sons whose mothers have received fertility treatment, but it is unknown whether the poor semen quality is related to the infertility treatment or to infertility per se, for example, whether it is caused by hereditable factors. Using data from a population-based, Danish follow-up study conducted in 2005-2006, the authors of the present study examined whether sons of subfertile couples who had not received fertility treatment had poorer semen quality than sons of fertile couples. Among the 311 participants, an inverse association between parental waiting time to pregnancy and both semen volume and total sperm count was observed (p trend = 0.04 and p trend = 0.046, respectively). Semen volume in sons of subfertile parents (pregnant after > or =1 years) was 19% lower in comparison with that in sons of parents whose waiting time to ...

Science.gov (United States)

A 33-year-old male of proven fertility suffered six attacks of malaria while resident in an African country. For this he received anti-malarial drugs. Semen analysis performed after the fourth attack, and repeated during the following 2 years after his return to Israel, revealed severe oligozoospermia, necrozoospermia and occasionally even azoospermia. Immunological examination of the patient revealed an inverse ratio of T-cell subsets and mast cell degranulation in response to palludrin. Twenty-five months after the last attack of malaria a significant improvement was found in semen quality and there was an increase in the ratio of T-helper to T-suppressor cytotoxic cells. These observations indicate that although malaria and its treatment may affect spermatogenesis, recovery may be expected eventually. PMID:3500921

UK PubMed Central (United Kingdom)

Most of the general population is exposed to carbaryl and other contemporary-use insecticides at low levels. Studies of laboratory animals, in addition to limited human data, show an association between...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the extrusion characteristics of magnesium alloy (AZ31), a computer simulation was attempted. Tensile properties of as-cast billet with different strain rates were incorporated into the simulation. The results showed a great change in distribution of stress and strain at near die region by the ram travel. It was found that the average grain size at longitudinal edge of the extruded sheet was smaller than that at center region, which might be attributed to recrystallization caused by severe plastic deformation. (orig.)

Science.gov (United States)

Experience in the diagnosis and treatment of infertility has led to an increased understanding of the prominent role male factors play in many couples' inability to conceive. While many forms of male factor infertility are amenable to treatment, for some patients there is no corrective therapy available. For this reason, a great deal of attention has been focused on developing technologies for semen processing and sperm utilization in cases of decreased semen quality. One area of research is the development of more sophisticated methods of assessing sperm function, as well as methods of sperm preparation. Progress is also being made in the application of technologies such as intrauterine insemination and in vitro fertilization in the treatment of male factor infertility. Such developments have improved prospects for fertility among patients suffering from decreased semen quality, as well as those suffering from such ...

British Library Electronic Table of Contents (United Kingdom)

Abstract Male infertility continues to be a clinical challenge of increasing significance. While male factors such as decreased semen quality are responsible for 25% of all infertility issues, the etiology of suboptimal semen quality is poorly understood. Many physiological, environmental, and genetic factors have been implicated, including oxidative stress. Oxidative stress is induced by reactive oxygen species (ROS), or free radicals, and although ROS are required for critical aspects of sperm function, excessive levels of ROS can negatively impact sperm quality. The origin of ROS generation, and the etiologies of increased ROS in men with suboptimal sperm quality have only recently been elucidated, offering multiple targets for potential therapy. Here, we present a critical review of th...

British Library Electronic Table of Contents (United Kingdom)

The quality of the end product from andrology services continues to lack consistency and in some cases fails to meet the needs of the end users (patients or clinicians). Results of external quality assessment (EQA) schemes continue to show unacceptably wide variation for the results of a single specimen. Some laboratories are able to show that the results of semen analyses relate to both natural and assisted pregnancy and are therefore useful in the management of the infertile couple, whereas others claim that their value is limited to the identification of severe male factor infertility. With wide variation in standardisation of methodology, levels of staff training and quality assurance, it is entirely understandable that such discrepancies persist. The following article proposes that Qu...

British Library Electronic Table of Contents (United Kingdom)

Fetal exposure to phthalates may be associated with adverse reproductive effects, including cryptorchidism and decreased semen quality. Information about human placental transfer is needed to qualify the hypotheses. A dual recirculating placenta perfusion system to monitor concentrations of eight phthalate monoesters in fetal and maternal perfusates was established. In addition to perfusate background measures of phthalate monoesters, the concentrations in umbilical cord plasma and placenta tissue were measured. Monomethyl phthalate (mMP), monoethyl phthalate (mEP), monobutyl phthalate (mBP), and mono (2-ethyl-hexyl) phthalate (mEHP) were detected in both maternal and fetal perfusate, demonstrating a release of compounds from tissue or blood to perfusates. The distribution of compounds bet...

British Library Electronic Table of Contents (United Kingdom)

Male infertility, characterized by hypogonadism, decreased semen quality or ejaculatory dysfunction, accounts for approximately 20% of infertility cases. Obesity and metabolic dysfunction have been identified, among other causal factors, to contribute to male infertility. In the context of the Western world's `obesity epidemic', this article discusses three main biological mechanisms linking obesity to impaired male reproductive function: hypogonadism, testicular heat stress/hypoxia-induced apoptosis and endocrine disruption by `obesogens'. Among these, obesity-induced hypogonadism is undoubtedly the most clinically significant and is easily assessed. Rapidly expanding areas of research in this area include leptin modulation of kisspeptins and hypothalamic-pituitary-testicular hormone path...

Science.gov (United States)

The primary objective was to assess the effects and clinical safety of a single high-dose of the third generation GnRH antagonist, acyline, on testicular characteristics in male dogs. Seven dogs were followed up weekly for six, 2-week periods (-2, -1, 1, 2, 3 and 4). At the end of the second period, they were given acyline (330 microg/kg sc). Responses to treatment varied among individual animals. Testicular consistency and scrotal diameter were slightly diminished (P>0.05) in Periods 1, 2, and 3. Libido and erection decreased during Periods 1 and 2 (Pdecreased semen quality with no adverse effects. PMID:17586037

Energy Technology Data Exchange (ETDEWEB)

As need for development of marginal and deepwater oil fields grows, demand increases for floating production vessels (FPVs) such as floating production, storage and offloading (FPSO) units; spread-moored production semi-submersibles; and turret-moored production vessels. The FPV may be purpose-built; or an existing vessel such as an exploration drilling semi-sub or ship-shape vessel may be modified to suit the purpose. In either case, requirements for tensioning systems for the mooring lines on the FPV are quite unique, and are not without the potential for problems when traditional chain windlasses or wire rope systems are employed. This two-part article discusses the range of available technologies and systems for tensioning mooring lines on FPVs. It examines problems of size, weight and safety associated with some available designs; and it considers in detail a specific family of new units. Part 1, presented here, discusses the FPV market, worldwide potential locations and different ...

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories contracted with Rockwell International Science Center to perform a series of narrowband, pseudo-random cyclic fatigue tests on sections of 6063-T651 aluminum, Darrius-type, vertical axis wind turbine (VAWT) airfoils. We designed and constructed a load member that was mounted within the frame of a rigid 200-kip servohydraulic, closed-loop test system to hold the VAWT section and permit cantilever bending along the shear centerline of the beam. A computer program was developed to synthesize a narrow band, pseudo-random load history with fixed root mean square (RMS) stress levels at a given bandwidth and central frequency. Six specimens each of two different weld configurations at the flange mounting plate were tested at several RMS stress levels with failure defined as visual observation of a 3-inch-long crack in the VAWT. In order to test at as great a frequency as possible, a 20-kip hydraulic ram with a 10-GPM servovalve was employed ...

Science.gov (United States)

Fetal exposure to phthalates may be associated with adverse reproductive effects, including cryptorchidism and decreased semen quality. Information about human placental transfer is needed to qualify the hypotheses. A dual recirculating placenta perfusion system to monitor concentrations of eight phthalate monoesters in fetal and maternal perfusates was established. In addition to perfusate background measures of phthalate monoesters, the concentrations in umbilical cord plasma and placenta tissue were measured. Monomethyl phthalate (mMP), monoethyl phthalate (mEP), monobutyl phthalate (mBP), and mono (2-ethyl-hexyl) phthalate (mEHP) were detected in both maternal and fetal perfusate, demonstrating a release of compounds from tissue or blood to perfusates. The distribution of compounds between perfusate, umbilical cord plasma, and tissue was in accordance with the physical-chemical properties of the compounds. Results from the present study of compounds residing in ...

British Library Electronic Table of Contents (United Kingdom)

Contents The aim of this study was a cytogenetic analysis of stallions semen to find sex chromosome aberrations and to determine if there was an association between stallion-s age and aberration frequency for the sex chromosomes. Sperm samples were collected from 22 stallions of various age from 3 to 23-years. Multicolour FISH was performed on each sample, using probes for the sex chromosomes and EGFR gene, localized on 4p12 in domestic horse. A total of 26199 sperm cells were analysed (from 1 070 to 1 532 per animal). Among the analysed cells, there were 50.318% with X chromosome, 48.543% with Y chromosome and 1.139% with aberrant chromosomes. The frequency of aberrations was: sex chromosomes nullisomy (0.466%), XY aneuploidy (0.454%), XX disomy (0.146%), YY disomy (0.041%), diploidy (0.0...

Energy Technology Data Exchange (ETDEWEB)

Metal oxide semiconductor (MOS) integrated circuits, with the benefits of low power consumption, represent the state of the art technology for implantable medical devices. Three significant sources of radiation are classified as having the ability to damage or alter the behavior of implantable electronics; Secondary neutron cosmic radiation, alpha particle radiation from the device packaging and therapeutic doses(up to 70 G{gamma}) of high energy radiation used in radiation oncology. The effects of alpha particle radiation from the packaging may be eliminated by the use of polyimide or silicone rubber die coatings. The relatively low incidence of therapeutic radiation incident on an implantable device and the use of die coating leaves cosmic radiation induced secondary neutron single event upset (SEU) as the main pervasive ionising radiation threat to the reliability of implantable devices. A theoretical model which predicts the susceptibility of a RAM cell to ...