bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Staphylococcus aureus Invasion into Bovine Mammary Epithelial Cells by Contact with Live Lactobacillus casei
Authors: Bouchard Damien S. , Rault Lucie , Berkova Nadia , Le Loir Yves , Even Sergine
Published: November 2012

Staphylococcus aureus
is a major pathogen that is responsible for mastitis in dairy herds.
S. aureus
mastitis is difficult to treat and prone to recurrence despite antibiotic treatment. The ability of
S. aureus
to invade bovine mammary epithelial cells (bMEC) is evoked to explain this chronicity. One sustainable alternative to treat or prevent mastitis is the use of lactic acid bacteria (LAB) as mammary probiotics. In this study, we tested the ability of
Lactobacillus casei
strains to prevent invasion of bMEC by two
S. aureus
bovine strains, RF122 and Newbould305, which reproducibly induce acute and moderate mastitis, respectively.
L. casei
strains affected adhesion and/or internalization of
S. aureus
in a strain-dependent manner. Interestingly,
L. casei
CIRM-BIA 667 reduced
S. aureus
Newbould305 and RF122 internalization by 60 to 80%, and this inhibition was confirmed for two other
L. casei
strains, including one isolated from bovine teat canal. The protective effect occurred without affecting bMEC morphology and viability. Once internalized, the fate of
S. aureus
was not affected by
L. casei
. It should be noted that
L. casei
was internalized at a low rate but survived in bMEC cells with a better efficiency than that of
S. aureus
RF122. Inhibition of
S. aureus
adhesion was maintained with heat-killed
L. casei
, whereas contact between live
L. casei
and
S. aureus
or bMEC was required to prevent
S. aureus
internalization. This first study of the antagonism of LAB toward
S. aureus
in a mammary context opens avenues for the development of novel control strategies against this major pathogen.
Biofilm as an Environment for Dissemination of
stx
Genes by Transduction
Authors: Solheim H. T. , Sekse C. , Urdahl A. M. , Wasteson Y. , Nesse L. L.
Published: November 2012

Dissemination of Shiga toxin (Stx)-encoding bacteriophages is the most likely mechanism for the spread of Stx-encoding genes and the emergence of new Stx-producing
Escherichia coli
(STEC). Biofilm has been reported to be a place where horizontal gene transfer by plasmid conjugation and DNA transformation may occur, and in this study, horizontal gene transfer by transduction has been demonstrated. Transfer of Stx-encoding bacteriophages to potentially pathogenic
E. coli
in biofilm was observed at both 20°C and 37°C. The infection rates were higher at 37°C than at 20°C. To our knowledge, this study is the first to show lateral gene transfer in biofilm mediated by a temperate bacteriophage. The study shows that the biofilm environment can be suitable for transduction events and can thereby be an environment for the emergence of new pathogenic
E. coli
.
The 3-Hydroxy-Methylglutaryl Coenzyme A LyaseHCL1Is Required for Macrophage Colonization by Human Fungal Pathogen Histoplasma capsulatum
Authors: Isaac Dervla T. , Coady Alison , Van Prooyen Nancy , Sil Anita
Published: November 2012

Histoplasma capsulatumis a fungal respiratory pathogen that survives and replicates within the phagolysosome of macrophages. The molecular factors it utilizes to subvert macrophage antimicrobial defenses are largely unknown. Although the ability ofH. capsulatumto prevent acidification of the macrophage phagolysosome is thought to be critical for intracellular survival, this hypothesis has not been tested sinceH. capsulatummutants that experience decreased phagosomal pH have not been identified. In a screen to identifyH. capsulatumgenes required for lysis of bone marrow-derived macrophages (BMDMs), we identified an insertion mutation disrupting theH. capsulatumhomolog of 3-hydroxy-methylglutaryl coenzyme A (HMG CoA) lyase (HCL1). In addition to its inability to lyse macrophages, thehcl1mutant had a severe growth defect in BMDMs, indicating that HMG CoA lyase gene function is critical for macrophage colonization. In other organisms, HMG CoA lyase catalyzes the last step in the leucine catabolism pathway. In addition, both fungi and humans deficient in HMG CoA lyase accumulate acidic intermediates as a consequence of their inability to catabolize leucine. Consistent with observations in other organisms, theH. capsulatumhcl1mutant was unable to grow on leucine as the major carbon source, caused acidification of its growth mediumin vitro, and resided in an acidified vacuole within macrophages. Mice infected with thehcl1mutant took significantly longer to succumb to infection than mice infected with the wild-type strain. Taken together, these data indicate the importance of Hcl1 function inH. capsulatumreplication in the harsh growth environment of the macrophage phagosome.
EptC of Campylobacter jejuni Mediates Phenotypes Involved in Host Interactions and Virulence
Authors: Cullen Thomas W. , O'Brien John P. , Hendrixson David R. , Giles David K. , Hobb Rhonda I. , Thompson Stuart A. , Brodbelt Jennifer S. , Trent M. Stephen
Published: November 2012

Campylobacter jejuni
is a natural commensal of the avian intestinal tract. However, the bacterium is also the leading cause of acute bacterial diarrhea worldwide and is implicated in development of Guillain-Barré syndrome. Like many bacterial pathogens,
C. jejuni
assembles complex surface structures that interface with the surrounding environment and are involved in pathogenesis. Recent work in
C. jejuni
identified a gene encoding a novel phosphoethanolamine (pEtN) transferase, EptC (Cj0256), that plays a promiscuous role in modifying the flagellar rod protein, FlgG; the lipid A domain of lipooligosaccharide (LOS); and several
N
-linked glycans. In this work, we report that EptC catalyzes the addition of pEtN to the first heptose sugar of the inner core oligosaccharide of LOS, a fourth enzymatic target. We also examine the role pEtN modification plays in circumventing detection and/or killing by host defenses. Specifically, we show that modification of
C. jejuni
lipid A with pEtN results in increased recognition by the human Toll-like receptor 4–myeloid differentiation factor 2 (hTLR4-MD2) complex, along with providing resistance to relevant mammalian and avian antimicrobial peptides (i.e., defensins). We also confirm the inability of aberrant forms of LOS to activate Toll-like receptor 2 (TLR2). Most exciting, we demonstrate that strains lacking
eptC
show decreased commensal colonization of chick ceca and reduced colonization of BALB/cByJ mice compared to wild-type strains. Our results indicate that modification of surface structures with pEtN by EptC is key to its ability to promote commensalism in an avian host and to survive in the mammalian gastrointestinal environment.
Are increased Foxp3+ regulatory T cells responsible for immunosuppression during HTLV-1 infection? Case reports and review of the literature
Authors: Barros Nicolas , Woll Fernando , Watanabe Luis , Montes Martin
Published: November 2012

Research of human T lymphotropic virus type I (HTLV-1)-associated diseases is mostly focused on inflammatory and lymphoproliferative disorders. However, the immunosuppressive consequences of HTLV-1 infection are frequently ignored. In developing countries where exposure to parasitic and other tropical diseases is frequent, the burden of disease is significantly increased by opportunistic infections. Regulatory T cells (Tregs) are a CD4 T-cell subset capable of suppressing effector responses. During HTLV-1 infection, CD4+Foxp3+ cells are increased in HTLV-1-associated leukaemia/lymphoma (ATLL) as well as in non-leukaemic presentations. However, controversy exists regarding the actual regulatory function of these cells. In this report, we present two cases of HTLV-1 ATLL complicated by parasitic organisms and we provide a brief review of the literature regarding FoxP3+ regulatory T cells and their role as a possible mechanism for the immunosuppressive manifestations that take place during HTLV-1 infection.
Not the usual sinusitis
Authors: Ammar Hussam , Kott Amy , Fouda Ragai
Published: November 2012

An encephalocele is a protrusion of the cranial contents beyond the normal confines of the skull. It is a rare cause of seizure in adults. A 38-year-old woman presented with a first-onset seizure. Brain CT was interpreted as right frontal sinus opacification suggestive of sinusitis. The patient was discharged home with an amoxicillin prescription. A few days later, she was re-admitted with another seizure. Careful evaluation of the brain CT and MRI revealed a right frontal sinus posterior wall defect and possible brain encephalocele. The patient had complained of chronic nasal discharge for years and had also noticed a watery discharge from her right nostril. We suspected cerebrospinal fluid rhinorrhea. A bifrontal craniotomy was performed, the encephalocele was resected and cranialisation of the frontal sinus was completed. The patient remained free of seizures at the last follow-up.
Administration of general anaesthesia to a paediatric patient with osteopetrosis
Authors: Ozer Ayse Belin , Erhan Omer L , Demirel Ismail , Ozcan Sibel
Published: November 2012

Osteopetrosis is a rare clinical syndrome characterised by the failure of bone resorption and remodelling, which causes multiple anatomical and physiological impairments. Pathological fractures can occur, in addition to, haemathological and metabolic impairments. Our patient was a 9-year-old girl diagnosed with osteopetrosis in the neonatal period. She had severe anaemia, thrombocytopaenia, hypocalcaemia, as well as growth and development delays. In this case report, the administration of general anaesthesia to the patient for a biopsy of the scalp and skull and a partial maxillectomy is presented.
Two different cases of postoperative symptomatic common carotid artery involvment in type A aortic dissection
Authors: Droeser Raoul A , Wolff Thomas , Mujagic Edin , Gürke Lorenz
Published: November 2012

Postoperative common carotid artery occlusion after reconstruction for type A aortic dissection can lead to major neurological morbidity. Surgical strategy to re-establish the cerebral perfusion depends on the time of onset of neurological deficits in this otherwise life-threatening disease. We present two cases with neurological deficits after replacement of the ascending aorta for a type A dissection treated with two different surgical strategies. In both cases, prompt surgical interventions improved neurological outcome.
R542X mutation in SMPD1 gene: genetically novel mutation with phenotypic features intermediate between type A and type B Niemann-Pick disease
Authors: Aneja Aradhana , Sharma Aditi , Dalal Ashwin , Sondhi Vishal
Published: November 2012

Niemann-Pick disease (NPD) is a heterogenous group of progressive neurovisceral disorder characterised by lysosomal accumulation of sphingomyelin. NPD types A and B are caused by mutations involving sphingomyelin-phosphodiesterase-1 (SMPD1) gene and are characterised by deficiency of acid sphingomyelinase activity. We present a case of a 9-month infant with clinical manifestations intermediate between types A and B NPD and genetically illustrating a novel R542X mutation in the exon 6 of SMPD1.
Cervical epidural abscess caused by brucellosis
Authors: Lampropoulos Christos , Kamposos Panagiotis , Papaioannou Ioanna , Niarou Vasiliki
Published: November 2012

A 70-year-old Greek lady presented with fever, arthralgias of knees, cervical and lumbar pain during the last month. On clinical examination the patient was found to have tenderness of the cervical and the lumbar spine with great motion restriction. The blood tests revealed high erythrocyte sedimentation rate and C-reactive protein, abnormal liver function tests and a positive rheumatoid factor. Serological test forBrucellawas positive while cervical MRI revealed epidural abscess and spondylodiscitis. Conservative treatment with streptomycin (it was substituted by rifampicin after the third week) and doxycyclin for 4 months significantly improved her symptoms. The frequency as well as the diagnosis and management of this manifestation are discussed.
Spontaneous monochorionic triplet pregnancy with no fetal anomaly or feto-fetal transfusion
Authors: Gandham Sahruda , Ogueh Onome
Published: November 2012

We present a case of spontaneously conceived monochorionic triamniotic triplet pregnancy with no fetal anomaly or feto-fetal transfusion. The mother developed gestational diabetes at 20 weeks gestation, and at 20 weeks and 4 days gestation triplet 2 was found to have selective growth restriction and absent end diastolic flow. Although laser treatment and clamping of the umbilical cord of the growth-restricted baby was considered, the management was conservative with regular ultrasound scans and antenatal corticosteroids at 24 weeks gestation, and the umbilical artery Doppler reverted to normal at 26 weeks and 4 days and growth velocity was maintained. An elective caesarean section was performed at 33 weeks gestation to deliver three boys in excellent condition who only required feeding support.
Osteochondroma mimicking deep vein thrombosis in a young cricketer
Authors: Watura Christopher , Patel Samir
Published: November 2012

Osteochondromas are bony outgrowths covered by thin cartilaginous caps, accounting for 35% of all benign bone tumours. The majorities are solitary and usually arise at the metaphysis of long bones. They may be associated with bursa formation, while vascular complications are rare. We report a 34-year-old man who presented with a 2-week history of pain, stiffness and swelling of the left lower leg following a cricket match. Clinically, a deep vein thrombosis (DVT) was suspected but D-dimer test was negative. Initial Doppler ultrasound scan (USS) was reported as showing a haematoma and possible DVT. A repeat Doppler USS did not detect a DVT, however the popliteal vein appeared collapsed and a pedunculated osteochondroma of the proximal tibia was found. An MRI confirmed this and also showed an extensive oedema around the calf muscles tracking distally in all compartments, most likely the result of a ruptured bursa.
A young patient with massive haematemesis
Authors: Abdulaziz Salman , Abou-Shala Nabil , Al-Sanouri Ibrahim
Published: November 2012

Aortoesophageal fistula (AEF) is a rare and life-threatening cause of gastrointestinal haemorrhage which requires emergency surgical intervention. We report a case of aortoesophageal fistula due to previous endovascular stent grafting to the ascending thoracic aorta after previous traumatic injury. The patient presented with catastrophic haematemesis which was managed by repeated deployment of endovascular stent graft and aortic bypass surgery; however, the patient ultimately died due to massive haemoptysis.
Delayed interval delivery in a triplet gestation
Authors: Wooldridge Rachel J , Oliver Emily A , Singh Tulika
Published: November 2012

A 27-year-old Ghanaian primigravida with a known triamniotic trichorionic triplet pregnancy presented at 17 weeks gestation following a miscarriage of one triplet at home. Examination and investigation revealed no signs of imminent delivery or infection. After careful counselling with regard to prognosis and options available for management, the couple opted for intervention including rescue cerclage. The patient received antibiotic prophylaxis for five days and daily progesterone suppositories until delivery. An ultrasound scan was performed every three weeks to monitor fetal growth and cervical length. At 24 weeks corticosteroids for fetal lung maturity were given. At 31 weeks gestation she experienced spontaneous rupture of membranes followed by active labour and forceps delivery. There were no maternal complications. Both babies were born in a good condition, but required ventilatory support for 72 h.
Intracystic papillary carcinoma of breast: report of three cases and review of the literature
Authors: Dhebri Alhad R , Ahmad Amna , Shah Nigam , Arora Pardeep K
Published: November 2012

Intracystic papillary carcinoma (IPC) of the breast is a rare malignant tumour, found mainly but not exclusively in elderly women. IPC may be asymptomatic or presents with a palpable mass or blood-stained nipple discharge. The tumour is encysted within a dilated duct with arborisation of the fibrovascular stroma and contains nodules of papillary carcinoma surrounded by a thick fibrous capsule. Frequently excisional biopsy is required for diagnosis. The mainstay of treatment is breast-conserving surgery or mastectomy. Sentinel node biopsy could be considered in invasive cases. Adjuvant radiotherapy (XRT) and/or endocrine therapy is considered in appropriate cases. Prognosis is excellent. We report three such cases of IPC, in elderly women, which were successfully treated.
Malaria and the heart
Authors: Bhat Smitha , Alva Jayaprakash , Muralidhara Krithika , Fahad Sayid
Published: November 2012

A 40-year-old healthy manual labourer from a malaria endemic area with no known risk factors for atherosclerotic coronary vascular disease was admitted to our hospital with a history of fever with chills and rigours. Physical examination revealed tachypnoea and icterus. Peripheral smear showed trophozoites ofPlasmodium vivaxand thrombocytopaenia. The patient was administered artesunate. Six hours after admission, he complained of severe substernal chest pain. A 12-lead ECG revealed ST elevations in leads I, II and aVL. Troponin T and creatine kinase MB were elevated and the random blood sugar was 49 mg%. Echocardiogram revealed left ventricle lateral wall hypokinesia. Hypoglycaemia was corrected. A provisional diagnosis of acute coronary syndrome as a complication of malaria or its treatment was made. He was treated with low molecular weight heparin and nitrates. The patient improved symptomatically. A repeat ECG was normal.
Idiopathic chylothorax in a young man
Authors: Desai Nayan , Chaddha Udit , Desai Shivang , Gable Brian
Published: November 2012

Chylothorax refers to the presence of chyle in the pleural space owing to disruption or obstruction of the thoracic duct or one of its tributaries. We present a case of non-traumatic, idiopathic chylothorax in an 18-year-old man. Lymphoscintigraphy was used to identify the site of leak. We tried the full armamentarium of available non-surgical therapy on him, including a modified diet, chest tube insertion, total parenteral nutrition and octreotide. Yet, despite optimal medical therapy, his effusion continued to persist. He eventually required thoracic duct ligation, which resulted in resolution of the effusion.
Heparin-induced thrombocytopenia associated with acute liver graft failure
Authors: Pannicke Nadine , Pollok Joerg-Matthias , Kluge Stefan , Petzoldt Martin
Published: November 2012

An orthotopic liver transplantation (OLT) is of a proven benefit in an acute liver failure (ALF). Heparin-induced thrombocytopenia (HIT) is strongly associated with thromboembolic complications. We present the case of a 56-year-old patient who underwent an OLT owing to an ALF of unknown aetiology. HIT type II with consecutive hepatic and portal vein thrombosis caused progressive graft failure. Total hepatectomy and porto-caval shunt were performed to reduce the toxic effects of liver cell necrosis such as multiorgan failure involving the respiratory, renal and cardiovascular systems. A suitable liver graft was allocated after an anhepatic bridging period of 56 h. Specific complications due to end-stage liver failure—such as acidosis, coagulopathy, decrease of vascular resistance, cerebral oedema, myocardial infarction and right heart failure—were treated. Following a re-OLT, the patient made a complete recovery. We present a rare case of HIT-associated early liver graft failure followed by a prolonged anhepatic phase and finally a successful re-OLT.
Repeated activation of mania by atypical antipsychotics in a patient
Authors: Raghunath Ashwati
Published: November 2012

A 50-year-old, white female patient was diagnosed with schizophrenia in her teens. Her illness did not respond adequately to treatment until she was placed on a combination of fluoxetine and conventional antipsychotics. She discontinued the conventional antipsychotics on a number of occasions, which caused her to become psychotic, but not manic. On two separate occasions she was placed on atypical antipsychotics that were associated with the occurrence of manic symptoms. Once the patient was restarted on conventional antipsychotics, she remained stable.
Polyarteritis nodosa presenting as haematuria following strenuous exercise
Authors: Bing Alison , Rich Charles , Keanie Julian Y , Ralston Stuart H , Stewart Grant D
Published: November 2012

Polyarteritis nodosa (PAN) can affect many organ systems but usually presents with a systemic illness characterised by malaise, weight loss, myalgia, arthralgia and signs of end-organ damage. Here, we report a case of PAN that presented acutely in a previously well 46-year-old man with visible haematuria and loin pain coinciding with an episode of strenuous exercise. Initially, the patient was thought to have suffered renal trauma, but subsequent investigations revealed intrarenal aneurysms typical of PAN which responded to immunosuppressive therapy. This case illustrates the importance of appropriate imaging for suspected urogenital tract trauma, that a high index of suspicion is required to make the diagnosis and that PAN can present with renal tract bleeding in the absence of obvious systemic features.
Hilar lymph node eroding into the pulmonary artery diagnosed by endobronchial ultrasound-guided transbronchial needle aspiration
Authors: Dhamija Amit , Agarwal Abhishek , Basu Arup , Bakshi Pooja
Published: November 2012

Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) is a novel minimally invasive procedure useful for the evaluation and diagnosis of mediastinal lymph nodes and the lung parenchymal lesions. A 75-year-old woman diagnosed as a case of infiltrating duct adenocarcinoma of left breast 15 years back for which she underwent a modified radical mastectomy followed by radiotherapy and chemotherapy. The patient presented to us with haemoptysis. During EBUS, the enlarged left hilar lymph node was seen to be eroding into the left pulmonary artery leading to a filling defect in the left pulmonary artery. This filling defect was first sampled by EBUS-guided TBNA followed by sampling of left hilar lymph node. The results of cytomorphology revealed malignancy which was compatible with a metastasis from a carcinoma breast. EBUS-TBNA is a novel, safe and minimally invasive procedure with a few complications.
Salmonella enteritidisinduced myocarditis in a 16-year-old girl
Authors: Childs Lucy , Gupta Sandy
Published: November 2012

Myocarditis typically presents with non-specific clinical symptoms, and can easily be missed in the absence of a high index of clinical suspicion. Myocarditis caused by bacterial pathogens is rare in immunocompetent individuals, more commonly seen following viral infection. Although more classically associated with typhoid fever and gastroenteritis,Salmonellaspecies are a rare cause of myocarditis. We report a case ofSalmonella enteritidis-induced myocarditis after gastrointestinal infection in a 16 year-old girl, and discuss the diagnostic tools currently utilised to ascertain the diagnosis.
Improving documentation of visual acuity in patients suffering facial fractures
Authors: Tahim Arpan Singh , Bryant Catherine , Greaney Lisa , Rashid Arif , Fan Kathleen
Published: November 2012

Failure to identify eye injuries associated with facial fractures can lead to life-altering morbidity. Oral and maxillofacial surgery teams receiving referrals of patients with these injuries have a vital role in ensuring that visual acuity (VA) is recorded at the time of presentation. We present a clinical audit of documentation of VA in 126 patients who sustained orbital floor and zygoma fractures. Our intervention involved a focussed teaching session for trainees responsible for taking such referrals. VA was appropriately documented in 16.5% before the session and 57.1% afterwards. This study shows that education of junior trainees gives rise to an increase in the proportion of patients where VA is properly documented. We suggest this teaching should occur routinely at junior doctor departmental inductions.
Emergency/disaster medical support in the restoration project for the Fukushima nuclear power plant accident
Authors: Morimura Naoto , Asari Yasushi , Yamaguchi Yoshihiro , Asanuma Kazunari , Tase Choichiro , Sakamoto Tetsuya , Aruga Tohru ,   Members of the Japanese Association for Acute Medicine, Emergency, Task Force on the Fukushima Nuclear Power Plant Accident (JAAM-TF-FNPPA)
Published: November 2012

The Fukushima Daiichi Nuclear Power Plant (1F) suffered a series of radiation accidents after the Great East Japan Earthquake on 11 March 2011. In a situation where halting or delaying restoration work was thought to translate directly into a very serious risk for the entire country, it was of the utmost importance to strengthen the emergency and disaster medical system in addition to radiation emergency medical care for staff at the frontlines working in an environment that posed a risk of radiation exposure and a large-scale secondary disaster. The Japanese Association for Acute Medicine (JAAM) launched the ‘Emergency Task Force on the Fukushima Nuclear Power Plant Accident’ and sent physicians to the local response headquarters. Thirty-four physicians were dispatched as disaster medical advisors, response guidelines in the event of multitudinous injury victims were created and revised and, along with execution of drills, coordination and advice was given on transport of patients. Forty-nine physicians acted as directing physicians, taking on the tasks of triage, initial treatment and decontamination. A total of 261 patients were attended to by the dispatched physicians. None of the eight patients with external contamination developed acute radiation syndrome. In an environment where the collaboration between organisations in the framework of a vertically bound government and multiple agencies and institutions was certainly not seamless, the participation of the JAAM as the medical academic organisation in the local system presented the opportunity to laterally integrate the physicians affiliated with the respective organisations from the perspective of specialisation.
The use of intermediates obtained from aminoglycolysis of waste poly(ethylene terephthalate) (PET) for the synthesis of water-reducible alkyd resin
Authors: Acar Işıl , Bal Ayça , Güçlü Gamze
Published: November 2012

In this study, depolymerization products obtained from an aminoglycolysis reaction of postconsumer poly(ethylene terephthalate) (PET) bottles were used for the synthesis of water-reducible alkyd resins for the first time. We also aimed to reduce the amount of amine using aminoglycolysis products of PET having amine end groups for the neutralization of alkyds in this work. Alkyds formulated to have an oil content of 50% were prepared with glycerine (G), ethylene glycol (EG), fatty acid (FA), and phthalic anhydride (PA) or aminoglycolysis depolymerization products (ADP). The “K alkyd constant system” was used for the formulation calculations of the alkyd resins. The K constant was 1.1 and the ratio of basic equivalents to acid equivalents (R) was 1.15. Physical and chemical film properties and thermal degradation stabilities of these alkyd resins were investigated. According to the results of surface coating tests, the properties of the waste PET-based alkyd resins were found to be compatible with the properties of the reference resins. In addition, thermal degradation stabilities of the water-reducible alkyd resins prepared by ADP were better than that of the reference resin. As a result, we concluded that aminoglycolysis products of waste PET are suitable for manufacturing water-reducible alkyd resins. Furthermore, the amount of amine used for the neutralization stage of preparing water-reducible resin was reduced by 50% using aminoglycolysis products having an amine end group.
Symmetry-adapted perturbation theory study for some magnesium complexes
Authors: Esrafili Mehdi D. , Yourdkhani Sirous
Published: November 2012

A systematic theoretical study on Mg–ligand interactions has been carried out employing both ab initio correlated wave function and density functional methods. The interactions of the Mg(CH3N2)2moiety with BF, CO, N2, NH3, and H2O ligands have been investigated by performing calculations at the B3LYP, MP2, MP4, and CCSD(T)/6–311++G(3df,3pd) levels of theory. Results indicate that the interaction energies of the Mg(CH3N2)2–L complexes increase in the order NH3 > H2O > BF > CO > N2. Symmetry-adapted perturbation theory (SAPT) analysis has been carried out to understand the nature of the forces involved in the bonding. The SAPT results indicate that the stabilities of the Mg–L interactions are attributed mainly to electrostatic effects, while induction and dispersion forces also play a significant role. The evaluated SAPT interaction energies for the Mg(CH3N2)2–L complexes are generally in good agreement with those obtained using the supermolecule CCSD(T) methods, suggesting that SAPT is a proper method to study the intermolecular interactions in these complexes. The results also suggest an explanation for the unique role of Mg2+as a carrier of water molecules that mediate enzymatic hydrolysis reactions.
Theoretical prediction of gas adsorption kinetics based on equilibrium data
Authors: Nieszporek Krzysztof , Banach Tomasz
Published: November 2012

Based on the equilibrium adsorption isotherms, new expressions describing the rate of adsorption were developed. The theoretical model takes into account the influence of diffusional effects on the rate of adsorption. Other nonideal effects such as surface energetic heterogeneity or intermolecular interactions can be taken into account by using the adequate equilibrium isotherm. The accuracy of the presented rate equations was verified using real adsorption systems.
In silico search for an endogenous anti-Alzheimer’s molecule — Screening amino acid metabolic pathways
Authors: Meek Autumn R. , Simms Gordon A. , Weaver Donald F.
Published: November 2012

Alzheimer’s disease (AD) is a neurodegenerative disorder arising from abnormal aggregation of β-amyloid (Aβ) and progressing at different rates from person to person. There may exist endogenous compounds within the brain that play a role in inhibiting aggregation. We have devised a unique in silico screening strategy of endogenous molecules within the human brain, with special emphasis on amino acid metabolic pathways, to identify compounds with the potential to inhibit Aβ aggregation. Metabolites of tryptophan were computationally identified through this screening as potential therapeutics and were optimized via molecular modelling to determine their capacity to bind to Aβ. The most successful molecule identified was 3-hydroxyanthranilic acid (3-HAA). This endogenous molecule was then computationally explored to design novel analogues of 3-HAA with the goal of improving Aβ antiaggregant activity. These combined in silico methods of screening, identifying, and successfully “analoguing” an endogenous molecule of the brain as an AD therapeutic has yielded positive results and a novel approach to computer-aided drug design.
Three different mechanisms for azo-ether hydrolyses in aqueous acid
Authors: Cox Robin A. , Buncel Erwin
Published: November 2012

It has been shown recently that most ethers hydrolyze in aqueous acid media not by the traditional A1 or A2 process, but by a mechanism involving rate-determining proton transfer to the substrate, concerted with C–O bond cleavage. The reactions of azoethers are more complicated, because the azo group can be protonated in the acid reaction medium as well. This protonation has to be accounted for in the kinetic analysis. Often it simply ties up the substrate in an unreactive form; the hydrolysis reaction slows down as a result of the azo-protonated compound not being the reactant in the hydrolysis. However, there are other possibilities. If the ether group is suitably located in the substrate the azo-protonated compound can react with three water molecules (a “water wire”) in a fast reaction, and the alkoxy group is lost as a result. Depending on the acidity, in this mechanism either the initial three-water attack, or the breakup of the resulting intermediate, can be rate-determining, and both of these were observed. A third possibility is that ring protonation of suitable substrates can occur, giving delocalized carbocations that can form a hydrolysis product in subsequent fast reactions. Thus, three different hydrolysis mechanisms for azoethers in acidic media can be observed. Six azoethers were studied, one of which contained two methoxy groups. Both of these hydrolyzed, but by different mechanisms.
Density functional theory study on the structural, reactivity, and electronic properties of all mono-, di-, tri-, tetra-, and penta-fluoroanilines as monomers for conducting polymers
Authors: Shirani Il Beigi Hossein
Published: November 2012

Electrical and structural properties of mono-, di-, tri-, tetra-, and penta-fluoroanilines as candidate monomers for new conducting polymers have been investigated using hybrid density functional theory (B3LYP/6–311+G**) based methods. The effects of the number and position of the fluorine atoms on the electrical and structural properties of fluoroanilines and their radical cations have also been investigated. The values of the vibrational frequencies, charge and spin-density distributions, ionization potentials, dipole moments, electric polarizabilities, HOMO-LUMO gaps, and the NICS values of these compounds have been calculated and analyzed as well. The results showed that the double bonds in 2-fluoroaniline and 2,5-difluoroaniline are more delocalized compared with other fluoroanilines; therefore, these molecules have the most aptitude for the electropolymerization reactions. The frequency analysis showed that the electrochemical stability of 2-fluoroaniline is greater than the other fluoroanilines. Also, this molecule possesses the largest NICS value compared to the other fluoroanilines. Consequently, 2-fluoroaniline has the largest ring current and the highest conductivity among all other monomers. Based on the results obtained, 2-fluoroaniline and 2,5-difluoroaniline are the best candidate monomers among all fluoroanilines for the synthesis of corresponding conducting polymers.
DFT/B3LYP Study of the Substituent Effects on the Reaction Enthalpies of the Antioxidant Mechanisms of Sesamol Derivatives in the Gas phase and water
Authors: Najafi Meysam , Najafi Mohammad , Najafi Houshang
Published: November 2012

In this paper, the study of various ortho and meta–substituted Sesamol derivatives is presented. The reaction enthalpies related to three antioxidant action mechanisms HAT, SET–PT, and SPLET for substituted Sesamols, have been calculated using the DFT/B3LYP method in gas phase and water. Calculated results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP), and electron transfer enthalpy (ETE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In the ortho position, substituents show a larger effect on reaction enthalpies than in the meta position. In comparison with the gas phase, water attenuates the substituent effect on all reaction enthalpies. In the gas phase, BDEs are lower than PAs and IPs, i.e., HAT represents the thermodynamically preferred pathway. On the other hand, the SPLET mechanism represents the thermodynamically favored process in water. Results show that calculated enthalpies can be successfully correlated with Hammett constants (σm) of the substituted Sesamols. Furthermore, calculated IP and PA values for substituted Sesamols show linear dependence on the energy of the highest occupied molecular orbital (EHOMO).
EFFICIENT METHOD FOR RELIABILITY ASSESSMENT UNDER HIGH-CYCLE FATIGUE
Authors: NOROUZI MAHDI , NIKOLAIDIS EFSTRATIOS
Published: November 2012

Fatigue causes about 90% of service failures in machines. Fatigue analysis involves significant randomness in the loads, material properties and geometry. Designers often use Monte Carlo simulation to estimate fatigue reliability under dynamic, random loads such as those due to ocean waves. Monte Carlo simulation is computationally expensive because it requires calculation of the stresses for thousands of simulated time histories of the loads. This paper presents and demonstrates a method to estimate efficiently the fatigue life of a structure subjected to a dynamic load, which is represented by a stationary, Gaussian random process, for many different spectra of the excitation. The method requires only one Monte Carlo simulation for one power spectral density function of the excitation.
A GENERALIZATION OF NIL-ARMENDARIZ RINGS
Authors: HABIBI MOHAMMAD , MANAVIYAT RAOUFEH
Published: November 2012

Let R be a ring, M a monoid and ω : M → End (R) a monoid homomorphism. The skew monoid ring R * M is a common generalization of polynomial rings, skew polynomial rings, (skew) Laurent polynomial rings and monoid rings. In the current work, we study the nil skew M-Armendariz condition on R, a generalization of the standard nil-Armendariz condition from polynomials to skew monoid rings. We resolve the structure of nil skew M-Armendariz rings and obtain various necessary or sufficient conditions for a ring to be nil skew M-Armendariz, unifying and generalizing a number of known nil Armendariz-like conditions in the aforementioned special cases. We consider central idempotents which are invariant under a monoid endomorphism of nil skew M-Armendariz rings and classify how the nil skew M-Armendariz rings behaves under various ring extensions. We also provide rich classes of skew monoid rings which satisfy in a condition nil (R * M) = nil (R) * M. Moreover, we study on the relationship between the zip and weak zip properties of a ring R and those of the skew monoid ring R * M.
ON THE LARGE STRAIN TORSION OF HCP POLYCRYSTALS
Authors: WU P. D. , WANG H. , NEALE K. W.
Published: November 2012

The large strain torsion of polycrystalline materials with the hexagonal close packed (HCP) crystallographic structure is numerically studied by using a special purpose finite element. All simulations are based on the recently developed large strain elastic visco-plastic self-consistent (EVPSC) model for polycrystalline materials. For the first time, the effect of twinning on the large strain torsion is assessed in the present study. It is found that the response of the large strain torsion of HCP polycrystals is very sensitive to the initial texture and texture evolution. Numerical results indicate that excluding texture evolution dramatically reduces the development of the second-order axial strain under free-end torsion, or the axial force under fixed-end torsion. It is also numerically demonstrated that twinning has a significant influence on the large strain torsion of HCP polycrystals. For the magnesium alloy AZ31 extruded bar, the predicted results are in good qualitative agreement with experimental observations.
EFFECT OF AGGREGATE SIZE AND GRADING ON THE FAILURE BEHAVIOR OF LIQUID RUBBER-BASED CONCRETE UNDER STATIC TENSION
Authors: AI SHIGANG , TANG LIQUN , FANG DAINING
Published: November 2012

The effect of the aggregate size and grading on the tensile strength and fracture behavior of Liquid rubber-based concrete (LRBC) are analyzed by a numerical approach. A 2D FE model was constructed in which the aggregates are represented by random distributed polygon and the interfaces are the areas surrounding each aggregate. The mechanical parameters of the rubber matrix and the bonding properties between the rubber matrix and aggregate were experimentally determined. Compressive testing of the LRBC specimens was first carried out to provide experimental benchmark for calibration of the proposed numerical model. Numerical simulations on static tension were then carried out using 39 generated specimens and the tensile stress–strain curves were obtained. It was found that with the increasing aggregate size, the tensile strength of LRBC increased steadily while the failure strain decreased. The LRBC samples with multi-grading of aggregate exhibit better mechanical properties with the higher tensile strength and larger failure strain. Based on the numerical analysis, the optimized grading design of the LRBC was recommended.
DEPENDENCY OF EFFECTIVE MODULUS OF POLYCRYSTALLINE AGGREGATES ON MACRO-GEOMETRIC CONFIGURATION
Authors: FAN HUI , XIE XIAOMEI
Published: November 2012

Polycrystalline aggregates are made in different macro-geometric configurations (line, thin film, bulk configurations etc.) for various engineering applications. Different mechanical behaviors and properties have been noticed among these configurations. In the present study, a finite element scheme with statistical consideration is employed to systematically investigate the effective modulus of polycrystalline copper in various geometric configurations. The numerical results show that the macro-scale geometric configuration is a key factor in determining the effective modulus of polycrystalline aggregates. The influence of microstructure on the effective modulus is examined by comparing the Voronoi model and uniform square grain model. The negligible discrepancy between the above two models indicates that the simple uniform model is feasible in simulating the real microstructure of polycrystalline aggregates with low and medium anisotropy.
ESTIMATION OF DYNAMIC SYSTEM'S EXCITATION FORCES BY THE INDEPENDENT COMPONENT ANALYSIS
Authors: AKROUT ALI , TOUNSI DHOUHA , TAKTAK MOHAMED , ABBÈS MOHAMED SLIM , HADDAR MOHAMED
Published: November 2012

This paper deals with a numerical investigation for the estimation of dynamic system's excitation sources using the independent component analysis (ICA). In fact, the ICA concept is an important technique of the blind source separation (BSS) method. In this case, only the dynamic responses of a given mechanical system are supposed to be known. Thus, the main difficulty of such problem resides in the existence of any information about the excitation forces. For this purpose, the ICA concept, which consists on optimizing a fourth-order statistical criterion, can be highlighted. Hence, a numerical procedure based on the signal sources independency in the ICA concept is developed. In this work, the analytical or the finite element (FE) dynamic responses are calculated and exploited in order to identify the excitation forces applied on discrete (mass-spring) and continuous (beam) systems. Then, estimated results obtained by the ICA concept are presented and compared to those achieved analytically or by the FE and the modal recombination methods. Since a good agreement is obtained, this approach can be used when the vibratory responses of a dynamic system are obtained through sensor's measurements.
EXACT EIGEN-RELATIONS OF CLAMPED-CLAMPED AND SIMPLY SUPPORTED PIPES CONVEYING FLUIDS
Authors: LU PIN , SHENG HONGYU
Published: November 2012

The exact eigen-equations of pipe conveying fluid with clamped-clamped and simply supported boundary conditions are derived. The simplified forms of the general eigen-equations for some specific cases are determined, and the corresponding dynamic properties are calculated and discussed. These properties provide a better understanding on the relationships between the dynamic stability and the flow velocities of the fluid-conveying components and help to design stable pipeline systems. In addition, the dynamic properties obtained by the exact eigen-equations can also serve as benchmark solutions for verifying results obtained by other approximate approaches.
MODELING BIOENERGY, LAND USE, AND GHG EMISSIONS WITH FASOMGHG: MODEL OVERVIEW AND ANALYSIS OF STORAGE COST IMPLICATIONS
Authors: BEACH ROBERT H. , ZHANG YUQUAN W. , MCCARL BRUCE A.
Published: November 2012

Biofuels production has increased rapidly in recent years due to higher petroleum prices as well as heightened concerns regarding climate change and energy security. However, because commercially viable biofuels are currently produced primarily from agricultural feedstocks, higher production volumes increase pressure on land resources. Thus, large-scale biofuels production has important implications for the forest and agriculture sectors, land use, trade, and net greenhouse gas (GHG) emissions. Competition for land is expected to continue growing in the future as mandated biofuels volumes increase along with rising demand for food, feed, and fiber, both domestically and internationally. In response to heightened concern regarding impacts such as indirect land-use change and higher food prices, the U.S. policy is focusing on second-generation (cellulosic) feedstocks to contribute the majority of the mandated increase in biofuels volume through 2022. However, there has been little work exploring the logistics of supplying these feedstocks or examining feedstock mix and net GHG effects of combining renewable fuels mandates with climate policy. In this paper, we apply the recently updated Forest and Agricultural Sector Optimization Model with GHGs (FASOMGHG) to explore the implications of alternative assumptions regarding feedstock storage costs and carbon price for renewable energy production mix, land use, and net GHG emissions. The model is used to quantify the magnitude and regional distribution of changes in the optimal mix of bioenergy feedstocks when accounting for storage costs. In addition, we find that combining the biofuels volume mandate with a carbon price policy has additional implications for feedstock mix and provides a substantially larger net reduction in GHG than a renewable fuels mandate alone.
Palaeoecology and sedimentology of Carboniferous glacial and post-glacial successions in the Paganzo and Río Blanco basins of northwestern Argentina
Authors: Dineen A. A. , Fraiser M. L. , Isbell J. L.
Published: November 2012

Recent studies show that Late Palaeozoic Ice Age (LPIA) climate change broadly affected marine invertebrate faunas: glaciations decreased origination and extinction and long-term gradual global warming during the final deglaciation altered palaeocommunity composition. Carboniferous stratigraphy and palaeoecology in the Paganzo and Río Blanco basins of southwestern Gondwana (present-day Argentina) were studied in ordered to further determine how palaeocommunities were influenced by glacial and post-glacial processes during the LPIA. In the Paganzo Basin, the Guandacol Formation consisted of an ice-proximal to very ice-distal glaciomarine succession, while the Tupe Formation represented continental fluvial lowstand sedimentation interrupted by periodic marine incursions (estuary setting). In the Río Blanco Basin, the Río del Peñon Formation represents a shallowing-upwards coastal marine facies under the influence of wave and storm activity. Diversity and abundance data from northwestern Argentina reflects that ice-proximal environments proved physiologically stressful to organisms, limiting colonization to only opportunistic fauna. Following glaciation, the fauna of northwestern Argentina diversified and became increasingly ecologically complex during two marine transgressions in the Río Blanco Basin. It is interpreted that palaeocommunity establishment, composition and diversification in western Argentina during the LPIA was mostly dependent upon localized environmental conditions and palaeogeographic location.