Nanofunctionalized zirconia and barium sulfate particles as bone cement additives

Zirconia (ZrO2) and barium sulfate (BaSO4) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles

DOES OPTIMAL CASH HOLDING MATTER IN MAINTAINING AND IMPROVING PROFITABILITY?

ABSTRACT   Purpose: This study was aimed to identify optimal cash holding factors and how they impacted the profitability of Pakistani-listed enterprises

Student’s Perception of Their Academics and Clinical Practice on Graduation from Dental Colleges of Peshawar

OBJECTIVE:The objective of the current study was to know the perception of students regarding dental curriculum in clinical practice and academics after their graduation in three dental colleges of Peshawar.MATERIAL AND METHODS:It was a cross-sectional study design, carried out at three dental colleges of Peshawar namely Khyber College of Dentistry, Sardar Begum Dental College and Peshawar Dental College. A total number of 193 house officers were there out of which93 participated in the study. A pilot study was conducted to assess the reliability of questionnaire. The study was conducted through a self-administered questionnaire. The questionnaire consisted questions about academics and clinical practice.RESULTS:Our sample consisted of 93 subjects. There were 79% females and 21% males. The results revealed an overall positive learning experience in undergraduate academics and clinical practice. Over 86% of the graduates were satisfied with their academics and about 69% were satisfied with clinical practice. Almost 90% of the subjects were confident in carrying out specific clinical procedures.CONCLUSION:The major conclusions were that academics and clinical practice was satisfactory to the majority of subjects, although some areas of concern were identified that need improvement

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives

Riaz Gillani1, Batur Ercan1, Alex Qiao3, Thomas J Webster1,21Division of Engineering, 2Department of Orthopaedics, Brown University, Providence, RI, USA; 3G3 Technology Innovations, LLC, Pittsford, NY, USAAbstract: Zirconia (ZrO2) and barium sulfate (BaSO4) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles.Keywords: orthopedic, nanotechnology, bone cements, osteoblast

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives

Zirconia (ZrO2) and barium sulfate (BaSO4) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilyl) propyl methacrylate (TMS), bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles

SUBBASE: An Authentication Scheme for Wireless Sensor Networks Based on User Biometrics

To keep a network secure, a user authentication scheme that allows only authenticated users to access network services is required. However, the limited resources of sensor nodes make providing authentication a challenging task. We therefore propose a new method of security for a wireless sensor network (WSN). Our technique, Secure User Biometric Based Authentication Scheme (SUBBASe), is based on the user biometrics for WSNs. It achieves a higher security level as well as improved network performance. This solution consists of easy operations and light computations. Herein, the proposed technique is evaluated and compared with previous existing techniques. This scheme increases the performance of the network by reducing network traffic, defending against DOS attacks, and increasing the battery life of a node. Consequently, the functionality and performance of the entire network is improved

Disease Spectrum in COVID-19 Cohort with Travel History from Iran

Background: Coronavirus disease 2019 (Covid-19), declared as a pandemic in March 2020, is an acute respiratory tract illness caused by coronavirus 2 (SARS-CoV2) with clinical manifestations ranging from mild upper respiratory tract symptoms to severe pneumonia. Objectives: To determine the disease spectrum of Covid-19 in a cohort with a travel history from Iran. Materials & Methods: This cross-sectional study with a retrospective collection of data was conducted at Agha Khan University, Karachi from 15th March to 19th April 2020. One hundred and fifty-five laboratory-confirmed cases of Covid-19 were recruited from a government quarantine facility. Data were obtained from the Punjab Emergency Services (Rescue 1122) database where a record of SARS-CoV-2 positive cases and quarantined persons is maintained. Study subjects with a travel history to Iran were contacted by telephone to obtain information about demographics, symptoms, and co-morbid conditions.  SPSS version 24 was used to analyze the data. Frequencies and percentages were calculated. Results: Among the returning travelers, 213 had laboratory-confirmed Covid-19, out of which 155 were included in this study. 56.1% were males with a mean age of 40 years. Among the study participants, 91.6% remained asymptomatic throughout the stay, while 8.4 % became symptomatic. 77.5% of the participants had received BCG vaccination in childhood. Among symptomatic cases 15.4% had asthma and 7.7% had hypertension. The most common clinical manifestation was cough which was present in 38.5% of the study participants. None died among the study participants. Conclusion: A mild presentation of COVID-19 was seen in our study participants with 91.6% among them being asymptomatic, while 8.4% were symptomatic. There was a high positivity rate in males as compared to females.

Fracture energy of fiber-reinforced and rubberized cement-based composites: A sustainable approach towards recycling of waste scrap tires

International audienceUsing crumb rubber particles obtained from end-of-life tires as aggregate in concrete can reduce the environmental overburden caused by the huge accumulation of these scrap tires. However, reduction in the mechanical properties of concrete is observed with the incorporation of rubber aggregates. To counter this detrimental effect of crumb rubber in concrete, amorphous metallic fibers are added to balance the loss in strength and durability issues. Mechanical characteristics along with the fracture energy of rubberized fiber-reinforced mortar are presented here. Four mortar mix compositions were investigated; the first one is reference mortar (control mortar), the second mix containing 30 kg/m 3 of metallic fibers, the third mix containing 30% of rubber aggregates as replacement of sand by equivalent volume and fourth containing both rubber aggregates and metallic fibers with the dosage 30% and 30 kg/m 3 , respectively. Compression tests, modulus of elasticity and direct tension tests were conducted for mechanical characterization. Deformation capacity, residual post-cracking strength and fracture energy of these composite mortar mixes were evaluated through uniaxial direct tension tests. The fracture energy was determined from the obtained complete softening curves. Test results show a reduction in mechanical properties with the incorporation of crumb rubber as aggregates in mortar. However, a significant increase in fracture energy was observed in rubberized fiber-reinforced mortar mixes. Moreover, the mortar mixes containing both rubber aggregates and metallic fibers show positive synergetic effect resulting in enhanced post-cracking residual tensile strength, strain capacity and energy dissipation capacity

Experimental Study on the Behaviour of Short Columns Confined by Waste Plastic Bags-Epoxy Composites

An experimental study was carried out to investigate the behaviour of short column confined by waste plastic bags and nylon strips and findings of this study are presented in this paper. Eight reinforced concrete (RC) short columns were casted. Among them two specimens were named as control, while remaining six specimens were divided into three groups [two specimens for each group] based on different confinement techniques investigated in this study. In retrofitting technique 1 (RT-1), RC short columns were externally confined by full wrap of plastic bags, while in retrofitting techniques 2 (RT-2) and 3 (RT-3), confinement was provided to the short columns by stirrups of nylon and plastic bags with 25 mm clear spacing, respectively. The testing under compression loading was performed on UTM of 100T capacity. From the results obtained, seismic parameters such as ductility, fracture energy before peak and after peak, factor k* and load-displacement response were studied. The results indicated that RC short column confined by RT-1 (full wrap) gives better performance in terms of ductility and fracture energy after peak. Increase in the ductility of RT-1 specimen was about 25% as compared to the control one. Moreover, post-peak fracture energy exhibited by short column confined through techniques RT-1 and RT-2 was 132 and 125 N/mm as compared to control one with 14 N/mm of fracture energy. The experimental observations further indicated that the failure of control specimen was sudden showing high brittleness while the failure of confined specimens by RT-1 and RT-2 techniques was observed to be gradual giving some warning before final failure