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1.
Sci Adv ; 6(7): eaay7661, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32110734

RESUMO

CuO is the only known binary multiferroic compound, and due to its high transition temperature into the multiferroic state, it has been extensively studied. In comparison to other prototype multiferroics, the nature and even the existence of the high-temperature incommensurate paraelectric phase (AF3) were strongly debated-both experimentally and theoretically-since it is stable for only a few tenths of a kelvin just below the Néel temperature. Until now, there is no proof by neutron diffraction techniques owing to its very small ordered Cu magnetic moment. Here, we demonstrate the potential of spherical neutron polarimetry, first, in detecting magnetic structure changes, which are not or weakly manifest in the peak intensity and, second, in deducing the spin arrangement of the so far hypothetic AF3 phase. Our findings suggest two coexisting spin density waves emerging from an accidental degeneracy of the respective states implying a delicate energy balance in the spin Hamiltonian.

2.
Nat Commun ; 9(1): 4368, 2018 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-30348968

RESUMO

The analysis of three-dimensional neutron spin polarization vectors, using a technique referred to as spherical neutron polarimetry (SNP), is a very powerful means of determining complex magnetic structures in magnetic materials. However, the requirement to maintain neutrons in a highly polarized state has made it difficult to use this technique in conjunction with extreme experimental conditions. We have developed a high pressure cell made completely of nonmagnetic materials and having no effect on neutron polarizations. Herein, we report the first SNP analyses under high pressure up to 4.0 GPa in the magnetoelectric multiferroic delafossite CuFeO2. This study also determined the complex spiral magnetic structures in these pressure-induced phases, by measuring the full neutron polarization matrix. The results presented herein demonstrate that the SNP measurements are feasible under high pressure conditions, and that this method is a useful approach to study pressure-induced physical phenomena.

3.
Sci Rep ; 8(1): 10665, 2018 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-30006614

RESUMO

(ND4)2[FeCl5(D2O)] represents a promising example of the hybrid molecular/inorganic approach to create materials with strong magneto-electric coupling. Neutron spherical polarimetry, which is directly sensitive to the absolute magnetic configuration and domain population, has been used in this work to unambiguously prove the multiferroicity of this material. We demonstrate that the application of an electric field upon cooling results in the stabilization of a single-cycloidal magnetic domain below 6.9 K, while poling in the opposite electric field direction produces the full population of the domain with opposite magnetic chirality. We prove the complete switchability of the magnetic domains at low temperature by the applied electric field, which constitutes a direct proof of the strong magnetoelectric coupling. Additionally, we refine the magnetic structure of the ordered ground state, deducing the underlying magnetic space group consistent with the direction of the ferroelectric polarization, and we provide evidence of a collinear amplitude-modulated state with magnetic moments along the a-axis in the temperature region between 6.9 and 7.2 K.

4.
Nat Commun ; 7: 10295, 2016 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-26776921

RESUMO

Apart from being so far the only known binary multiferroic compound, CuO has a much higher transition temperature into the multiferroic state, 230 K, than any other known material in which the electric polarization is induced by spontaneous magnetic order, typically lower than 100 K. Although the magnetically induced ferroelectricity of CuO is firmly established, no magnetoelectric effect has been observed so far as direct crosstalk between bulk magnetization and electric polarization counterparts. Here we demonstrate that high magnetic fields of ≈ 50 T are able to suppress the helical modulation of the spins in the multiferroic phase and dramatically affect the electric polarization. Furthermore, just below the spontaneous transition from commensurate (paraelectric) to incommensurate (ferroelectric) structures at 213 K, even modest magnetic fields induce a transition into the incommensurate structure and then suppress it at higher field. Thus, remarkable hidden magnetoelectric features are uncovered, establishing CuO as prototype multiferroic with abundance of competitive magnetic interactions.

5.
Oral Oncol ; 49(8): 818-23, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23683469

RESUMO

OBJECTIVES: The chewing habit of paan, chhaliya, and tobacco is common in the traditional culture of Pakistan. Currently, niswar, gutka and manpuri are also commercially available in the Pakistani market. Epidemiologic evidences and increased rate of oral squamous cell carcinoma (OSCC) cases may indicate a direct relationship of these chewing habits with oral carcinogenesis. The p53 gene has been known to be a tumor suppressor gene that is found mutated in common human cancers. The p53 gene contains a single nucleotide polymorphism at codon 72 of exon 4 which encodes either proline (Pro) or arginine (Arg). The aim of the present study was to investigate association of p53 gene codon 72 polymorphism with patients of oral squamous cell carcinoma consuming these carcinogenic chewable materials. MATERIALS AND METHODS: Blood and tissue samples of 260 OSCC patients were collected with informed consent from the local hospitals of Karachi. The patients were compared with controls of similar age and sex. The exon 4 of p53 gene was examined by PCR-SSCP. The tumor samples showing mobility shift were purified and sequenced. RESULTS: The C>G missense mutation at nucleotide position 215 of the coding sequence was identified which substitutes proline with arginine at codon 72 of p53 protein. When the data for CCC72CGC polymorphism was analyzed statistically, a significant difference was observed between OSCC and control samples. The Pro allelic frequencies were significantly higher in OSCC patients as compare to controls. The current study indicated the Pro form of p53 codon 72 increases the risk of developing OSCC in Pakistani population. The risk ratio for Pro allele was 1.5004 (95% confidence interval: 1.2559 to 1.7924) and odds ratio of Pro allele was 2.389 (95% confidence interval: 1.5591 to 2.8137) in comparison with the Arg and Pro alleles in the OSCC group. CONCLUSION: These evidences suggest that there may be specific genetic targets with these chewing ingredients that are responsible for causing OSCC. The p53 codon 72 polymorphism is associated with OSCC at somatic cell level but the polymorphism was not associated at inherited level.


Assuntos
Areca , Arginina/genética , Carcinoma de Células Escamosas/etiologia , Genes p53 , Predisposição Genética para Doença , Neoplasias Bucais/etiologia , Polimorfismo Genético , Prolina/genética , Sequência de Bases , Carcinoma de Células Escamosas/genética , Cocarcinogênese , Primers do DNA , Humanos , Neoplasias Bucais/genética , Paquistão , Reação em Cadeia da Polimerase
6.
J Pak Med Assoc ; 59(3): 186-90, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19288954

RESUMO

OBJECTIVE: To establish the presence and quantify Ethanol in commercially available mouthwashes. METHODS: Samples from twelve commercially available mouthwashes were tested for the presence of Ethanol followed by the estimation of percentage of Ethanol in five brands in Pakistan Council of Scientific and Industrial Research (P.C.S.I.R) and Husein Ebrahim Jamal (H.E.J.) labs, Karachi. RESULTS: Ten out of twelve brands of mouthwashes were found to be Ethanol positive. CONCLUSION: Alcohol (Ethanol) in the mouthwashes does not contribute to any therapeutic action. It is alarming to find the presence of alcohol in the mouthwashes which claim to contain no alcohol.


Assuntos
Etanol/efeitos adversos , Antissépticos Bucais/efeitos adversos , Cromatografia Gasosa , Humanos , Espectroscopia de Ressonância Magnética , Saúde Bucal
7.
J Coll Physicians Surg Pak ; 18(11): 723-5, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18983801

RESUMO

A large solitary multiloculated pelvic cyst in a 40-year-old woman with chronic pelvic pain was diagnosed to be a Multicystic Benign Mesothelioma (MBM) of peritoneum at laparotomy. Operative findings showed dense adhesions between uterus and bladder anteriorly, small intestines and pouch of Douglas posteriorly, a right ovarian cyst cm containing clear serous fluid and two nodular deposits were seen in the pouch of Douglas, small multiple deposits was found over the mesentery of small intestine and parietal peritoneum. Total abdominal hysterectomy with bilateral oophorectomy and infracolic omentectomy was done. During surgery, there was injury to the small intestine hence, resection of 10 inches of small intestine with re-anastomosis was carried out. Postoperative recovery was satisfactory. At 3 years follow-up, patient is symptom-free.


Assuntos
Mesotelioma Cístico/diagnóstico , Neoplasias Ovarianas/diagnóstico , Neoplasias Pélvicas/diagnóstico , Dor Pélvica/diagnóstico , Neoplasias Peritoneais/diagnóstico , Adulto , Feminino , Humanos , Histerectomia/métodos , Mesotelioma Cístico/patologia , Mesotelioma Cístico/cirurgia , Omento , Neoplasias Ovarianas/patologia , Neoplasias Ovarianas/cirurgia , Ovariectomia , Neoplasias Pélvicas/patologia , Neoplasias Pélvicas/cirurgia , Dor Pélvica/patologia , Dor Pélvica/cirurgia , Neoplasias Peritoneais/patologia , Neoplasias Peritoneais/cirurgia
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