Natural rubber (NR) latex gloves are widely used as a very important barrier for healthcare workers. However, they
can still be perforated easily by sharp devices and instruments. The aim of this study was to investigate the effect of the
addition of graphene oxide (GO) to low-ammonia NR latex on its puncture resistance, mechanical properties and thermal
stability. GO was synthesized using modified Hummers’ reaction. The produced GO was mixed into the NR latex solution at
various doses (0.01-1.0 wt. %), followed by a coagulant dipping process using ceramic plates to produce film samples.
Puncture resistance was enhanced by 12% with 1.0 wt. % GO/NR. Also, the incorporation of GO improved the stress at
300% and 500%, the modulus at 300% and 500% and the tear strength of low-ammonia NR latex films.
Bahan aloi pateri dalam kumpulan Sn-Ag-Cu (SAC) merupakan bahan pematerian yang bebas plumbum digunakan secara
meluas dalam industri elektronik. Antarasambungan pateri bertindak untuk menghubungkan komponen elektronik pada
papan litar bercetak (PCB). PCB memainkan peranan yang penting dalam tindak balas pematerian dan mikrostruktur
antarasambungan pateri-substrat seterusnya mempengaruhi kebolehharapan suatu sambungan pateri. Pes pateri
Sn0.3Ag0.7Cu (SAC0307) dipaterikan pada tiga jenis PCB iaitu PCB tanpa salutan (PCB/Cu) sebagai sampel kawalan,
PCB dengan salutan timah (PCB/Sn) dan PCB dengan salutan nikel (PCB/Ni). Kajian ini bertujuan untuk mengkaji kesan
salutan permukaan PCB ke atas pertumbuhan sebatian antara logam (IMC) selepas uji kaji penuaan sesuhu yang berbeza
selama 1000 jam. Keputusan menunjukkan purata ketebalan lapisan IMC ~ 5.7 μm serta kadar pertumbuhan lapisan IMC
yang paling rendah adalah selari dengan tenaga pengaktifan tertinggi dengan salutan Ni iaitu 41 kJ/mol berbanding
PCB/Cu dan PCB/Sn. Ini bermakna salutan Ni pada PCB mampu mengawal pertumbuhan IMC sehingga lebih kurang 40%
berbanding salutan Sn dan tanpa salutan.
Bioactive composites consist of pseudowollastonite and mullite synthesized from natural resources was developed for
bone implant applications. To realize such applications, a mechanical test of these composites and in vitro bioactivity in
SBF solution were studied. The present paper reports pseudowollastonite synthesized from the rice husk ash and limestone
reinforced with 10, 20 and 30 wt. % of mullite. Influence of sintering temperature, phase composition, morphology towards
mechanical properties of various pseudowollastonite-mullite (PSW-M) composites was examined prior to the bioactivity
test. It was found that pseudowollastonite with the addition of 20 wt. % of mullite sintered at 1150°C gave the best result
for diametral tensile strength (DTS) and hardness with the value of 8.8 ± 0.15 MPa and 3.79 ± 0.13 GPa, respectively.
The obvious increment in the mechanical strength was due to the formation of liquid phase CaAl2
O3
during sintering at
1150°C. In addition, the formation of fibrous apatite (HA) layer of amorphous calcium phosphate (ACP) with Ca/P ratio
1.8 on PSW20M sample confirmed the good bioactivity of the composite.
Neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease are characterized by the progressive loss of
neurons. One of the contributing factors for these diseases is oxidative stress, characterized by the imbalance of free
radicals production and antioxidant defense mechanisms. In the present study, the neuroprotective effects of Ocimum
basilicum var. thyrsiflora against hydrogen peroxide (H2
O2
)-induced oxidative stress in SK-N-SH neuroblastoma cells
were evaluated. The exposure of SK-N-SH cells to 50 µM H2
O2
for 24 h induced cytotoxicity and apoptosis as measured
by cell viability and flow cytometry, respectively. Pretreatment with ethyl acetate (ObEA) fraction at 3.1-25 µg/mL showed
the highest protection against H2
O2
-induced cell death compared to other fractions and crude extract by increasing cell
viability and reducing apoptosis. The evaluation of antioxidant capacity via 1, 1-diphenyl-2-picrylahydrazyl (DPPH)
and ferric reducing/antioxidant power (FRAP) assays showed ObEA possessed the highest antioxidative properties. The
intracellular reactive oxygen species (ROS) production of H2
O2
in untreated cells increased by 2.39-fold compared to the
control and was significantly attenuated by the 2 h pre-treatment of O. basilicum (p<0.05). The reduction in intracellular
superoxide dismutase (SOD) induced by H2
O2
was also abrogated by the pretreatment of O. basilicum. These findings
suggested that O. basilicum is potentially neuroprotective against oxidative damage in neuronal cells by scavenging free
radicals, restoring SOD activities and eventually prevent cell death.
Solitary plasmacytoma (SP) is a tumor with evidence of clonal plasma cells and no other features of multiple myeloma
(MM). We report a case of SP which showed multiple recurrences of SP and then evolution into overt MM. A 56-year-old
man presented with the 5-month-history of right nasal obstruction and intermittent epistaxis. He had SP (extraosseous) of
right nasopharynx (3.5 × 2 × 2.5 cm), with no paraproteinaemia. He received radiotherapy (56 Gy), achieving complete
remission. Ten years later, he had recurrence of SP (osseous) in left tibia, presenting with pathological fracture. He
received radiotherapy (50 Gy), achieving partial response. Three years later, he had recurrence of SP (osseous) in right
tibia, presenting with right leg pain. He received radiotherapy (45 Gy). While receiving treatment, he had progressive
swelling in the area around right eye, double vision and headache. Imaging scans showed multiple plasmacytomas. There
were presence of monoclonal paraprotein, hypercalcemia and lytic bone lesions. He was diagnosed as MM (at the age
of 70 years) and treated with Bortezomib-based therapy. Currently, after one cycle of treatment, clinical improvement is
achieved. The importance of multi-disciplinary team approach for managing patients with plasmacytoma is highlighted
in order to achieve the holistic approach of management.
Cancer always presents a big problem that endangers human health. In recent years, the use of gene therapy in cancer
research has significantly increased. This study aimed to construct a non-viral, wild-type, recombinant eukaryotic
expression vector, pEGFP-N1-p53/MAR and verify its mechanism of action in cancer cells in vitro. This investigation
provides a novel strategy for p53 gene therapy via regulation of the matrix attachment region (MAR), potentially laying a
foundation for the establishment of an anticancer protein bioreactor. The p53 gene was cloned from human peripheral blood
and the MAR gene was amplified from chicken liver tissue. The recombinant eukaryotic expression vector pEGFP-N1-p53/
MAR was constructed using an E. coli self-replication system. LipofectamineTM 2000 was used as the transfection agent
to deliver the plasmid into the human hepatic carcinoma (HEP3B) cell line. We divided the groups as follows: negative
control cells without plasmid transfection, vehicle control cells transfected with the PEGFP-N1 vector, and experimental
cells transfected with the pEGFP-N1-p53/MAR vector. Cells in each well of the vehicle control and experimental groups
were transfected with 1.6 μg of plasmid and 3 μL of liposome. The cellular morphology of each group was analysed
using green fluorescence microscopy at 12, 24, 36 and 48 h. Then, statistical analysis of the apoptosis rates among
the three groups was performed using SPSS. The ultrastructures of the cells were observed via transmission electron
microscopy after transfection for 24 h. Morphological analysis showed that the cells of the experimental group were
shrunken and reduced in size and their intercellular connections had disappeared. Additionally, the apoptosis rate in the
experimental group was significantly higher than that in the control groups and the cellular microstructure showed that
heterochromatin and apoptotic bodies were found in the experimental group. In conclusion, compared with the control
groups, the pEGFP-N1-p53/MAR plasmid can effectively promote Hep3B cell apoptosis in vitro.
Karboksimetil kitosan menunjukkan potensi untuk digunakan sebagai polimer induk bagi aplikasi elektrolit polimer
pepejal. Kesan garam litium nitrat terhadap sifat elektrokimia elektrolit polimer pepejal berasaskan karboksimetil kitosan
telah dijalankan. Elektrolit polimer pepejal berasaskan karboksimetil kitosan disediakan melalui teknik pengacuan
larutan dengan nisbah garam litium nitrat (LiNO3
) yang berbeza. Pencirian filem telah dijalankan dengan menggunakan
spektroskopi inframerah transformasi Fourier-pantulan penuh kecil (ATR-FTIR) dan Spektroskopi Impedans Elektrokimia
(EIS) bagi penentuan interaksi kimia dan sifat elektrokimia polimer elektrolit tersebut. Spektrum ATR-FTIR menunjukkan
ion litium cenderung untuk berinteraksi dengan kumpulan karbonil dan kumpulan ester dalam struktur karboksimetil
kitosan. Kekonduksian ion tertinggi yang dicapai adalah 8.44 × 10-4 S cm-1 dengan kepekatan garam 30 bt. % LiNO3
pada suhu bilik dan 5.25 × 10-3 S cm−1 pada suhu 70°C. Filem karboksimetil kitosan-30% LiNO3
mencapai kestabilan
secara elektrokimia sehingga 2.94 V. Keputusan kajian yang diperoleh menunjukkan elektrolit polimer pepejal berasaskan
karboksimetil kitosan memberi satu tarikan baru bagi aplikasi bateri ion litium.
Borylated porphyrin is one of building blocks in coupling reactions to obtain the multiporphyrin containing two,
three or more subunits of porphyrins. In this study, one of borylated porphyrin derivatives, 5-(4,4,5,5 – tetramethyl
– 1,3,2 – dioxoborolane) -10,20 – diphenylporphyrin (B-DPP) was synthesized through four steps of reactions. The
building block of porphyrin, dipyrromethane was synthesized through a condensation reaction in the presence of
trifluoroacetic acid as catalyst. Subsequently, A2
B2 type of porphyrin was obtained by Lindsey condensation reaction
followed by bromination reaction to produce porphyrin halide. Suzuki cross coupling reaction between porphyrin
halide and pinacolborane with Pd (II) catalyst afforded 40% of borylayed porphyrin. The product was successfully
characterized by using nuclear magnetic resonance spectroscopy (NMR) and UV-Visible spectroscopy (UV-Vis). This
compound crystallized from a mixture of dichloromethane/methanol to give violet needle-like crystal. Crystallographic
studies showed this compound crystallized in monoclinic system with space group of P21
/c.
Polyalthia cinnamomea Hook.f. & Thomson (Annonaceae) or locally known as ‘Larak Batu Bukit’, ‘Pisang-pisang’,
‘Sugao’ and ‘Sigumpet Hutan’ is a small woody plant found throughout Malaysia and Singapore. In this study, the
basic chemical components from the leaves of the plant were fractionated and the antibacterial activity as well
as the major constituents of the basic fraction was determined. To the best of our knowledge, this is the first study
being carried out on the bioactivity and phytochemistry of P. cinnamomea. The basic fraction remarkably inhibited
the growth of ten bacteria tested except one. The biggest inhibitory diameter and the lowest minimum inhibitory
concentration were 19.0±4.6 mm and 0.125 mg/mL against respective Bacillus subtilis and Bacillus thuringiensis.
Gas chromatography-mass spectrometry (GCMS) analysis of the basic fraction identified four major cyclosiloxanes
of octamethylcyclotetrasiloxane (18.1%), decamethylcyclopentasiloxane (16.4%), dodecamethylcyclohexasiloxane
(14.1%) and tetradecamethylcycloheptasiloxane (6.0%). The knowledge of the antibacterial potential of P. cinnamomea
basic fraction and the major constituents present in the fraction can be utilized in the fields of natural products,
pharmaceutical, cosmetic and personel care industries.
This study was aimed to investigate the effect of ZnO-decorated GO nanocomposite material loaded with different weight
percent of ZnO toward polysulfone (PSF) mixed-matrix membrane (MMM) performance enhancement. ZnO-decorated
GO nanocomposite material was loaded with 1, 5, 10 and 20 wt. % ZnO was blended with PSF polymer and fabricated
through phase inversion process. The performance of the fabricated MMMs were evaluated by measuring membrane
permeability, bovine serum albumin rejection (BSA) and flux recovery ratio (FRR). Experiment results demonstrated
that the PSF/ZnO-GO MMM performances were greatly improved where 10 wt. % ZnO loaded into ZnO-decorated GO
nanomaterial exhibited the highest permeability (5.35 L/m2
·h·bar) and BSA retention at all pH state among all fabricated
mixed-matrix membranes. Additionally, FRR was also dramatically improved attributed to the smoother membrane surface.
This work has shown that a well distribution of ZnO with the help of GO nanosheet as a dispersing agent blended with
PSF polymer to form PSF/ZnO-GO MMM was a promising approach in creating better ultrafiltration (UF) membrane with
a better hydrophilicity, permeability, and cleaning efficiency for the used in food industry in future.
Biosensor optik berasaskan hemoglobin (Hb) terpegun pada mikrosfera poli(n-butil akrilat-co-N-akriloksisuksinimida)
[poli(nBA-NAS)] telah dibangunkan bagi mengesan kepekatan ion nitrit (NO2
-
). Kompleks HEM ferum dalam Hb
memangkinkan tindak balas penurunan ion NO2
-
kepada nitrik oksida (NO) lalu bergabung dengan deoksihemoglobin
(HbFe2+) membentuk kompleks ferum-nitrosil-hemoglobin (HbFe2+-NO) yang berwarna hijau kekuningan. Spektrofotometer
pantulan gentian optik digunakan untuk memantau kepekatan ion NO2
-
secara kuantitatif berdasarkan perubahan warna
Hb terpegun pada mikrosfera poliakrilat daripada perang kemerahan ke hijau kekuningan pada panjang gelombang
pantulan maksimum 668 nm. Pencirian terhadap biosensor nitrit reflektometrik melibatkan ujian kesan pH, kesan
kepekatan Hb, julat rangsangan linear, kebolehasilan, jangka hayat dan kesan gangguan ion telah dijalankan. Biosensor
ion NO2
- optik terbangun memaparkan julat linear dinamik daripada 5 hingga 50 mg mL-1 (R2
=0.9894) pada pH7.0 dengan
had pengesanan (LOD) sebanyak 3.3 mg mL-1 dan nilai sisihan piawai relatif (RSD) kebolehasilan biosensor sebanyak
5.8%. Jangka hayat biosensor optik nitrit tersebut adalah selama 36 hari dan majoriti ion asing yang sering wujud
bersama ion NO2
- dalam sampel air semula jadi tidak menunjukkan kesan gangguan yang bererti terhadap penentuan
ion NO2
-
menggunakan biosensor optik terbangun kecuali ion Hg2+, Ag+, Br-
dan S2-.
MeSH terms: DNA-Directed DNA Polymerase; Hemoglobins; Biosensing Techniques; Gentiana
Fermentation has been long used as a method to produce beverage of various health benefits. In this research, ripe papaya
(Carica papaya) was fermented through alcoholic fermentation using Saccharomyces cerevisiae, followed by acetous
fermentation using Acetobacter spp. from mother of vinegar, to reduce wastage of this highly perishable Malaysian
fruit. The papaya juice was pasteurised prior to the fermentation process. Optimisation of acetous fermentation was
carried out using the response surface methodology (RSM) with central composite rotatable design (CCRD). Acetous
fermentation time had shown significant effect on all the chemical characteristics while mother of vinegar concentration
did not significantly effect on all the chemical characteristics. The vinegar-like fermented papaya beverage which was
produced at the optimum point (Fermentation time = 70.80 h and concentration = 40% mother of vinegar) contained
0.37 ± 0.01% reducing sugar, 3.54 ± 0.36% ethanol, 2.46 ± 0.07% acetic acid, 327.89 ± 3.60 mg GAE/ L total phenolic,
2.32 ± 0.17 mg/100 mL ascorbic acid and 52.40 ± 0.23% mg AA/100 mL free-radical scavenging activity. In conclusion,
vinegar-like fermented papaya beverage was successfully produced and its chemical compositions changed from papaya
juice to wine and vinegar-like beverage with increased bioactive compounds and antioxidative activity.
This study was carried out to determine the antioxidant activity, total phenolic content (TPC) and piperine in oleoresin
extract of pepper retting waste water. Fresh pepper berries were soaked in distilled water (1:2 w/w) and allowed to ret
at four different temperatures: 28, 35, 42 and 49°C for a total of 16 days. The retting waste water was collected on the
4th, 8th, 12th and 16th day and was then subjected to dichloromethane liquid extraction prior to analyses. The results
showed that highest (p<0.05) oleoresin yield (271.34 ± 28.09 mg/g), antioxidant activity in DPPH (84.58 ± 4.93%),
FRAP assay (49.55 ± 6.11 mM TE/g) and total phenolic content (5.64 ± 0.06 mg GAE/g) obtained at low temperature and
shorter days of retting (28°C, day 4). Whilst at high temperature with longer days of retting (49°C, day 16) resulted in
significantly higher (p<0.05) piperine content (1.81 ± 0.44%) in the waste water. Thus, the findings showed that the
agro-industrial waste water produced during white pepper processing contain valuable bioactive oleoresins and other
functional compounds which could be explored in details.
Thirteen formulations of cinnamaldehyde/non-ionic surfactant/water system nanoemulsions were prepared using highpressure homogenisation. The result showed that varying the cinnamaldehyde/surfactant ratio had effect significantly
(p<0.05) to mean droplet diameter, polidispersity index, ζ-potential, turbidity and whiteness index, while no significant
effect (p>0.05) to viscosity. The mean droplet diameter ranged from 50.48 to 106.4 nm, polydispersity index from 0.06 to
0.28 and ζ-potential from -4.11 to -6.98 mV. The smallest droplet size was produced using 5% cinnamaldehyde and 5%
Tween 80. Response surface for droplet diameter showed that the higher the cinnamaldehyde and surfactant concentrations,
the larger the droplet diameter, polydispersity index and whiteness index. However, the ζ-potential increased as the
cinnamaldehyde concentration decreased and Tween 80 increased. Increasing the cinnamaldehyde concentration led
to an increase in turbidity. Formulation of 5% cinnamaldehyde and 6.23% Tween 80 gave no observable separation of
the nanoemulsion with minimum droplet size, polidispersity index, viscosity, turbidity, whiteness index and maximum
ζ-potential in modulus. The stability of the optimum formulation was sustained for 10 days upon storage at 4°C. The
values of droplet diameter, PDI and ζ-potential were 55.50 nm, 0.08 and -5.38 mV, respectively.
Amphibians have undergone catastrophic declines worldwide and the major histocompatibility complex (MHC) is an
attractive candidate for investigating the link between adaptive variation and individual fitness. Nonetheless, little research
has been conducted to study the amphibians MHC genes. Thus, MHC class Ia of Odorrana margaretae, a representative
species of the Odorrana, was isolated and used to analyze the adaptive mechanism. We isolated alleles and determined
evolution patterns of MHC class Ia in O. margaretae. The phylogenetic tree of MHC class Ia was reconstructed to
understand the evolutionary relationship of Anura. In O. margaretae of MHC class Ia: there were more non-synonymous
mutations compared to synonymous mutations; there are at least two loci; the recombination alleles took place for a
large proportion (55.56%) of the alleles and recombination usually took place between whole exon of Ia genes of MHC
class; positive selection sites were detected and most (10 of 19) located at the α1 and α2 domains belonged to the
presumed ABS. The diversity of genes of MHC class Ia was led by recombination, gene duplication and positive selection.
Trans-species polymorphisms of anuran genes of MHC class Ia were evident in anurans. Therefore, the MHC class Ia
present demonstrative candidates for investigating the link between adaptive variation and individual fitness. We argue
that knowledge of the MHC of other anuran lineage, especially focusing a genus such as O. margaretae, should provide
an overall more complete picture of the organization of MHC in anurans.
Termites are found in various habitats, particularly diverse communities occurring in tropical forest and peatlands.
Termites are beneficial insects, which function as soil engineers, improving the soil quality. However, in peatlands
converted to commercial oil palm plantations, they are considered as pests. There is lack of studies on termite communities
in converted peatlands in Peninsular Malaysia. Thus, this study investigated termite species associated with oil palm
stands in three soil types (clay, shallow peat and deep peat) in Endau Rompin Plantation. The stand scouting method
was used to record the numbers and types of termites associated with palm trees in the individual stands on different
soil types. A total of 29 termite species associated with the palm stands were identified morphologically. All the species
belonged to the families Rhinotermitidae and Termitidae. Twenty-three of the 29 species were found in the shallow peat,
16 in clay soil and 15 in deep peat. The community structure was synthesized by two-way cluster analysis with Sorensen
(Bray Curtis) distance measure. Five termite groups associated with two soil types (clay soil and shallow/deep peat)
were generated. Moisture levels and organic content were likely to determine the presence of soil feeders identified in
the presence study. This study provides information on the status of termite species in oil palm plantation areas. Such
information may be useful in future planning strategies by the plantation management.
The mangrove plant is known to produce secondary metabolite compounds, mainly isoprenoids. Polyisoprenoids (dolichol
and polyprenol) are known to have antimicrobial, anticancer and antiviral activity. Therefore, this study aimed to
determine the cytotoxic effects of polyisoprenoids from Rhizophora mucronata and Ceriops tagal leaves by evaluating
the induction of apoptosis and cell cycle arrest and the inhibition of the expression of Bcl-2 and cyclin D1 in WiDr colon
cancer cells. Cell death was determined based on IC50 values in MTT assays. The induction of apoptosis and alterations
in the cell cycle were observed by flow cytometry. The expression of Bcl-2 and cyclin D1 proteins, which play a role in
apoptosis and cell cycle regulation, was observed by immunocytochemistry. The results showed that polyisoprenoids
from R. mucronata and C. tagal leaves exhibited toxicity against the WiDr cell line, with IC50 values of 278 ± 5.77 and
276 ± 9.54 µg/mL, respectively. Polyisoprenoids from R. mucronata and C. tagal leaves significantly induced apoptosis
and caused cell cycle arrest in G0/G1 phase, while also decreasing the expression of Bcl-2 and cyclin D1. Our results
confirmed that polyisoprenoids from R. mucronata and C. tagal leaves have the potential to be developed as anticancer
agents for colon cancer.
This study assesses the influence of water quality on fish occurrences in Sungai Pahang, Maran District, Pahang, Malaysia. Water quality and fish samplings were conducted at seven sampling sites in the district for 13 consecutive months. We used canonical correspondence analyses (CCA) to determine the influence of water quality on monthly fish species occurrences. The ranges of water quality parameters were quite high considering the measurements were made during rainy and dry seasons throughout the year. A total of 2,075 individual fish was captured which comprised of 22 different families and 65 species. Family Cyprinidae recorded the highest number of fish species of the area (27 species; 41.5%), followed by Bagridae (five species; 7.69%) and Pangasiidae (five species; 7.69%). Three fish species categorized as endangered, including Balantiocheilos melanopterus, Probarbus jullieni and Pangasianodon hypophthalmus were also collected. The collected fish species were divided into three groups (A to C), which was clearly separated in the CCA ordination diagram. The most important water quality variables for the fish occurrences in this river were pH, followed by temperature, conductivity, alkalinity and phosphate. Data analysis indicates that the occurrence of fishes were influenced by a combination of water quality parameters, but not associated with sampling month. The results present a new data from a study of fish assemblage and their habitat condition which may be important in fisheries activity and fish conservation of the river in the future.
In this report, we demonstrate that continuous improvement in XPS instruments and the calibration standards as well
as analysis with standard component-fitting procedures can be used to determine the binding energies of compounds
containing phosphorus and sulfur of different oxidation states with higher confidence. Based on such improved XPS
analyses, the binding energies (BEs) of S2p signals for sulfur of increasing oxidation state are determined to be 166-167.5
eV for S=O in dimethyl sulfoxide, 168.1 eV for S=O2
in polysulfone, 168.4 eV for SO3
in polystyrene sulfonate and 168.8
eV for SO4
in chondroitin sulfate. The BEs of P2p signals show the following values: 132.9 eV for PO3
in triisopropyl
phosphite, 133.3 eV for PO4
in glycerol phosphate, 133.5 eV for PO4
in sodium tripolyphosphate and 134.0 eV for PO4
in sodium hexametaphosphate. These results showed that there are only small increases in the binding energy when
additional oxygen atoms are added to the S-O chemical group. A similar result is obtained when the fourth oxygen or
poly-phosphate environment is added to the phosphorus compound. These BE values are useful to researchers involved
in identifying oxidation states of phosphorus and sulfur atoms commonly observed on modified surfaces and interfaces
found in applications such as biomaterials, super-capacitors and catalysis.
The effects of mixed-valence Mn substitution at the Cu site on the superconducting and elastic properties of
La1.85-1.5xSr0.15+1.5xCu1-xMnx
O4
(x = 0, 0.02 and 0.04) were studied. The samples were characterized by X-ray diffraction
(XRD) method, temperature-dependent resistance measurements, scanning electron microscopy (SEM) and sound velocity
measurements at room temperature. An elastic softening and a decrease in the critical temperature Tc
was observed as
Mn was substituted for Cu. The Debye temperature θD for x = 0 and 0.02 void free samples were calculated to be 459 K
and 430 K, respectively. Internal lattice strain which is related to lattice parameter ratio a/c did not correlate with Tc
. The
electron-phonon coupling estimated using the conventional Bardeen-Cooper-Schrieffer (BCS) theory was λ = 0.367 (x =
0) and 0.368 (x = 0.02). The electron-phonon coupling in two-dimensional van Hove scenario was calculated to be λvH
= 0.0148 (x = 0) and 0.0149 (x = 0.02). These results were compared with other cuprates and related superconductors.
The comparison showed that other than electron-phonon coupling, the elastic moduli might play an important role in
the mechanism of superconductivity in these materials.