Application of fracture mechanics for energetic effects predictions while wood sawing     

Kazimierz A. Orlowski  Tomasz Ochrymiuk  Anthony Atkins  Daniel Chuchala 《Wood Science and Technology》2013,47(5):949-963

In the classical approach, energetic effects (cutting forces and cutting power) of wood sawing process are generally calculated on the basis of the specific cutting resistance, which is in the case of wood cutting the function of more or less important factors. On the other hand, cutting forces (or power—more interesting from energetic point of view) could be considered from a point of view of modern fracture mechanics. Cutting forces may be employed to determine not only toughness but also shear yield strength, which are then applied in the models. Furthermore, forecasting of the shear plane angle for the cutting models, which include fracture toughness in addition to plasticity and friction, broadens possibilities of energetic effects modelling of the sawing process even for small values of the uncut chip. Mentioned models are useful for estimation of energetic effects of sawing of every kinematics. However, for band saws and circular sawing machines, the chip acceleration power variation as a function of mass flow and tool velocity ought to be included in analysis of sawing at larger cutting speeds.  相似文献   

Interaction of tea polyphenols and food constituents with model gut epithelia: the protective role of the mucus gel layer     

D'Agostino EM  Rossetti D  Atkins D  Ferdinando D  Yakubov GE 《Journal of agricultural and food chemistry》2012,60(12):3318-3328

The luminal surface of the gastrointestinal tract is covered by a mucus gel layer that acts to protect gut epithelial cells from the harsh luminal environment. This study investigated the use of two human colonic adenocarcinoma cell lines, HT29-MTX-E12 and HT29, as a model to mimic gut epithelium with and without a mucus gel layer. The effect of adding the tea polyphenols epigallocatechin gallate (EGCG) and epicatechin (EC) to the cells with subsequent examination of cell morphology and viability was assessed. EGCG, at the concentrations tested, was very toxic to the HT29 cells, but less toxic to the HT29-MTX-E12 cells, suggesting that the mucus gel layer on the HT29-MTX-E12 cells can protect the cells against EGCG toxicity. In contrast, EC had no effect on the viability of either the HT29 or HT29-MTX-E12 cells, suggesting that proteins within the mucus gel layer on the apical surface of gut epithelial cells may bind to the galloyl ring of EGCG. The effect of adding food-related ingredients with the ability to complex with EGCG, β-casein and maltodextrin, on cell viability was also examined. The presence of β-casein was very effective in protecting the cells against the toxicity effect of EGCG, but maltodextrin, at the concentration tested, was less effective in protecting against this toxicity. In conclusion, the results demonstrate that the mucus gel layer on HT29 human colonic adenocarcinoma cells may protect these cells against EGCG toxicity. In addition, the data showing reduced toxicity of EC compared to that of EGCG suggest that the cytotoxic effects of high polyphenol levels may be associated with the ability of polyphenols to interact with cellular proteins and mucins.  相似文献   

The effect of select seminal plasma proteins on endometrial mRNA cytokine expression in mares susceptible to persistent mating‐induced endometritis          下载免费PDF全文

CE Fedorka  KE Scoggin  EM Woodward  EL Squires  BA Ball  MHT Troedsson 《Reproduction in domestic animals》2017,52(1):89-96

In the horse, breeding induces a transient endometrial inflammation. A subset of mares are unable to resolve this inflammation, and they are considered susceptible to persistent mating‐induced endometritis PMIE Select seminal plasma proteins cysteine‐rich secretory protein‐3 (CRISP‐3) and lactoferrin have been shown to affect the innate immune response to sperm in vitro. The objective of this study was to determine whether the addition of CRISP‐3 and lactoferrin at the time of insemination had an effect on the mRNA expression of endometrial cytokines in susceptible mares after breeding. Six mares classified as susceptible to PMIE were inseminated during four consecutive oestrous cycles with treatments in randomized order of: 1 mg/ml CRISP‐3, 150 μg/ml lactoferrin, seminal plasma (positive control) or lactated Ringer's solution (LRS; negative control) to a total volume of 10 ml combined with 1 × 10⁹ spermatozoa pooled from two stallions. Six hours after treatment, an endometrial biopsy was obtained for qPCR analysis of selected genes associated with inflammation (pro‐inflammatory cytokines interleukin (IL)‐1β, IL‐8, tumour necrosis factor (TNF)‐α, interferon (INF)‐γ, anti‐inflammatory cytokines IL‐1RN and IL‐10, and inflammatory‐modulating cytokine IL‐6). Seminal plasma treatment increased the mRNA expression of IL‐1β (p = .019) and IL‐8 (p = .0068), while suppressing the mRNA expression of TNF (p = .0013). Lactoferrin also suppressed the mRNA expression of TNF (p = .0013). In conclusion, exogenous lactoferrin may be considered as one modulator of the complex series of events resulting in the poorly regulated pro‐inflammatory response seen in susceptible mares.  相似文献   

Reported Resuscitation of a Hypothermic Avalanche Victim With Assisted Ventilation in 1939     

Ken Zafren  Dale Atkins  Hermann Brugger 《The Forestry Chronicle》2018,29(2):275-277

  相似文献   

Ovulation,Pregnancy Rate and Early Embryonic Development in Vernal Transitional Mares Treated with Equine‐ or Porcine‐FSH     

T Raz  MD Amorim  BC Stover  CE Card 《Reproduction in domestic animals》2010,45(2):287-294

The objective of this study was to compare the efficacy of purified equine‐ and porcine‐FSH treatment regimes in mares in early vernal transition. Mares (n = 22) kept under ambient light were examined ultrasonographically per‐rectum, starting January 30th. They were assigned to one of two treatment groups using a sequential alternating treatment design when a follicle ≥ 25 mm was detected. In the eFSH group, mares were treated twice daily with equine‐FSH, and in the pFSH group mares were treated twice daily with porcine‐FSH; treatments were continued until follicle(s) ≥ 35 mm, and 24 h later hCG was administered. Oestrous mares were inseminated with fresh semen and examined for pregnancy on days 11–20 post‐ovulation. In the eFSH group, 11/11 (100%) mares developed follicle(s) ≥ 35 mm, 8/11 (73%) ovulated and 6/8 (75%) conceived. In the pFSH group, 5/11 (45%) developed follicle(s) ≥ 35 mm, 4/11 (36%) ovulated and 3/4 (75%) conceived. Treatment with eFSH resulted in a greater ovarian stimulation; higher number of pre‐ovulatory‐sized follicles, higher number of ovulations and higher number of embryos (p < 0.05). Following ovulation, serum progesterone concentrations were correlated with the number of CLs and supported early embryonic development; maternal recognition of pregnancy occurred in all pregnant mares. We concluded that eFSH can be used to effectively induce follicular growth and ovulation in vernal transitional mares; however, if bred, diagnosis and management of twins’ pregnancies would be required prior to day 16 because of the increased risk of multiple embryos per pregnancy. Conversely, the current pFSH treatment regime cannot be recommended.  相似文献   

Transplacental Transfer of Iron in the Water Buffalo (Bubalus bubalis): Uteroferrin and Erythrophagocytosis     

FTV Pereira  FC Braga  KC Burioli  JR Kfoury Jr  LJ Oliveira  PC Papa  AF Carvalho  CE Ambrósio  FW Bazer  MA Miglino 《Reproduction in domestic animals》2010,45(5):907-914

The objectives of this investigation were to understand transplacental transport of iron by secreted uteroferrin (UF) and haemophagous areas of water buffalo placenta and clarify the role(s) of blood extravasation at the placental‐maternal interface. Placentomes and interplacentomal region of 51 placentae at various stages of gestation were fixed, processed for light and transmission electron microscopy, histochemistry and immunohistochemistry. Haemophagous areas were present in placentomes collected between 4 and 10 months of pregnancy. Perl’s reaction for ferric iron was negative in placentomes, but positive in endometrial glands. Positive staining for UF indicated areas in which it was being taken up by phagocytosis and/or fluid phase pinocytosis in areolae of the interplacentomal mesenchyme, with little staining in endometrial stroma. Imunohistochemistry detected UF in trophectoderm of haemophagous regions of placentomes and in other parts of the foetal villous tree, but the strongest immunostaining was in the epithelial cells and lumen of uterine glands. Ultrastructural analyses indicated that erythrophagocytosis was occurring and that erythrocytes were present inside cells of the chorion that also contained endocytic vesicles and caveolae. Results of this study indicate that both the haemophagous areas of placentomes and the areolae at the interface between chorion and endometrial glands are important sites for iron transfer from mother to foetal‐placental tissues in buffalo throughout pregnancy.  相似文献   

Endothelin receptor subtype A blockade does not affect the haemodynamic recovery from haemorrhage during xenon/remifentanil or isoflurane/remifentanil anaesthesia in dogs     

Roland CE Francis  Claudia Höhne  Adrian Klein  Udo X Kaisers  Philipp A Pickerodt  Willehad Boemke 《Veterinary anaesthesia and analgesia》2010,37(3):258-268

ObjectiveTo test the compensatory role of endothelin-1 when acute blood loss is superimposed on anaesthesia, by characterizing the effect of systemic endothelin receptor subtype A (ET_A) blockade on the haemodynamic and hormonal responses to haemorrhage in dogs anaesthetized with xenon/remifentanil (X/R) or isoflurane/remifentanil (I/R).Study designProspective experimental randomized controlled study.AnimalsSix female Beagle dogs, 13.4 ± 1.3 kg.MethodsAnimals were anaesthetized with remifentanil 0.5 μg kg^?1 minute^?1 plus either 0.8% isoflurane (I/R) or 63% xenon (X/R), with and without (Control) the systemic intravenous endothelin receptor subtype A antagonist atrasentan (four groups, n = 6 each). After 60 minutes of baseline anaesthesia, the dogs were bled (20 mL kg^?1) over 5 minutes and hypovolemia was maintained for 1 hour. Continuous haemodynamic monitoring was performed via femoral and pulmonary artery catheters; vasoactive hormones were measured before and after haemorrhage.ResultsIn Controls, systemic vascular resistance (SVR), vasopressin and catecholamine plasma concentrations were higher with X/R than with I/R anaesthesia at pre-haemorrhage baseline. The peak increase after haemorrhage was higher during X/R than during I/R anaesthesia (SVR 7420 ± 867 versus 5423 ± 547 dyne seconds cm^?5; vasopressin 104 ± 23 versus 44 ± 6 pg mL^?1; epinephrine 2956 ± 310 versus 177 ± 99 pg mL^?1; norepinephrine 862 ± 117 versus 195 ± 33 pg mL^?1, p < 0.05). Haemorrhage reduced central venous pressure from 3 ± 1 to 1 ± 1 cmH₂O (I/R, ns) and from 8 ± 1 to 5 ± 1 cmH₂O (X/R, p < 0.05), but did not reduce mean arterial pressure, nor cardiac output. Atrasentan did not alter the haemodynamic and hormonal response to haemorrhage during either anaesthetic protocol.Conclusions and clinical relevanceSelective ET_A receptor blockade with atrasentan did not impair the haemodynamic and hormonal compensation of acute haemorrhage during X/R or I/R anaesthesia in dogs.  相似文献   

Efficacy of digoxin for treatment of cats with dilated cardiomyopathy     

C E Atkins  P S Snyder  B W Keene  J E Rush  S Eicker 《Journal of the American Veterinary Medical Association》1990,196(9):1463-1469

The role of digoxin in treatment of cats with dilated cardiomyopathy and other forms of myocardial failure is unclear. We evaluated the chronotropic and inotropic effects of digoxin by comparing baseline, noninvasive indices of cardiac performance with those obtained after 9 +/- 1.3 (mean +/- SEM) days of digoxin treatment in 6 cats with heart failure attributable to dilated cardiomyopathy. Two-dimensionally directed, M-mode echocardiography and electrocardiography were used to determine left ventricular shortening fraction, preejection period (PEP), ejection time (LVET), PEP to LVET ratio, velocity of circumferential fiber shortening, electromechanical systole, heart rate, and PR interval. Treatment consisted of administration of furosemide (mean dosage, 2.4 mg/kg of body weight/day), digoxin in tablet form (approximately 0.01 mg/kg, q 48 h), aspirin (80 mg, q 48 h), and a commercial low-salt diet. In addition, 2 cats were administered short-term, low-dose fluids IV, and 2 were given taurine supplementation at rates of 500 and 1,000 mg/day. Other off-loading or inotropic agents were not administered. Therapeutic or toxic serum digoxin concentration was achieved in all cats. Significant (P less than 0.05) improvement was detected in mean values for shortening fraction, PEP, PEP to LVET ratio, and velocity of circumferential fiber shortening. Mean electromechanical systole and LVET did not change significantly. Improvement, as assessed by indices of cardiac function, was documented in 4 of the 6 cats treated with digoxin, including the 2 cats given taurine supplementation. In the cats given taurine, positive inotropic effect was observed prior to the time when taurine-induced improvement in ventricular function is detectable.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

THE USE OF M-MODE ECHOCARDIOGRAPHY IN DETERMINING CARDIAC OUTPUT IN DOGS WITH NORMAL, LOW, AND HIGH OUTPUT STATES: COMPARISON TO THERMODILUTION METHOD     

Clarke E.  Atkins  DVM  Michael B.  Curtis  DVM  PhD  Sheila M.  McGurik  DVM  PhD  Mark D.  Kittleson  DVM  PhD  Takashi  Sato  DVM  MS  Patti S.  Snyder  DVM  MS 《Veterinary radiology & ultrasound》1992,33(5):297-304

The utility of M-mode echocardiographic determination of left ventricular volume and cardiac output was evaluated by comparing four commonly used formulae for ventricular volume, derived from end-systolic (ESD) and end-diastolic (EDD) ventricular dimensions. Cardiac index (CI) was calculated by the following formulae, where HR = heart rate and BSA = body surface area (M²): 1. (EDD³- ESD³) * HR/BSA; 2. (0.85 * EDD³ - 1.2 *ESD³) * HR/BSA; 3. (EDD^3.16 - ESD^3.16) * HR/BSA; and 4. {[7/(2.4 + EDD)] * [EDD³] - [7/(2.4 + ESD)] * [ESD³)}* HR/BSA. Cardiac index, obtained invasively by thermodilution, was compared to values determined echocardiographically in normal dogs (Group 1) and in three states of altered cardiac function: after positive inotropic stimulation with graded doses (0,5,10, and 15 μg/kg/min) of intravenous dobutamine (Group 2); with experimentally induced heartworm disease (Group 3); and with spontaneous dilated cardiomyopathy (Group 4). Cardiac index, determined echocardiographically, was plotted against CI, determined with thermodilution, and regression equations calculated. In Group 1 (n = 15), a significant relationship (P < 0.01) was observed with each of the four formulae (r²= 0.54-0.68), however, individual estimates of CI were often inaccurate. With inotropic stimulation (Group 2;3 normal dogs, n = 12 data points), the relationship was significant (P < 0.05), but the coefficients of determination were less than in the unstimulated normal dogs (r²= 0.41-0.47). No significant relationship was seen between CI, determined echocardiographically and CI, determined by thermodilution, when overt cardiac disease was present (Groups 3 and 4; n = 7 and 13, r²= 0.13-0.21, respectively). Specific formulae were evaluated for accuracy by comparing their coefficients of determination and their ability to predict mean and individual measured CI. Using the paired Student's t-test, CI determined noninvasively were shown to differ significantly (P < 0.05) between methods and between formulae in many instances. No one formula was found to be consistently more accurate than the others. We conclude that, in normal dogs, while echocardiographic estimation of CI is significantly related to CI measured with thermodilution, individual variation diminishes clinical utility. However, this noninvasive technique should prove useful in comparing populations with minimal or no cardiac dysfunction. Secondly, the relationship is diminished, but not lost, after inotropic stimulation. M-mode echocardiographic estimation of CI offers little promise for accurate assessment of cardiac performance in cardiac disease states. Lastly, although none of the four formulae for CI compared herein were found to be consistently superior to the other three, formulae 3 and 4 appear to be most useful in estimating CI in normal dogs.  相似文献   

Seminal Leucocytary Profile in Beef Bulls     

AL Zart  VCL Jurgielewicz  CE Fernandes 《Reproduction in domestic animals》2014,49(5):719-724

Despite evidences that seminal leucocytes could affect semen quality, references for the frequency and concentration of these cells in bulls are not available. The aim of this study was to determine the normal concentration of leucocytes in beef bulls and to correlate this characteristic with semen quality. First, 57 bulls from artificial insemination centres were evaluated to obtain the normal leucocytary profile values. Next, 382 bulls were subjected to breeding soundness evaluation. The average concentration of leucocytes in bovine semen was 4.73 × 10⁶/ml. Unsatisfactory bulls showed a higher number of leucocytes/field than that in the satisfactory ones. Logistic regression analysis revealed that the unsatisfactory bulls showed 6.5‐fold more chances of having higher leucocyte counts than satisfactory ones. Values of up to 1 leucocyte/field in the bull ejaculate are considered physiologically normal, whereas >5 leucocytes/field is associated with poor semen quality.  相似文献