A Novel Strategy for Poly(β-alanine-b-lactone)s: Sequentially HTP and AROP

Efkan Çatıker,Ayçanur Hamzaçebi 한국고분자학회 2022 Macromolecular Research Vol.30 No.5

A series of poly(β-alanine-b-lactone)s were prepared by combination of hydrogen-transfer polymerization (HTP) of acrylamide and anionic ring-opening polymerization (AROP) of β-propiolactone, α-methyl propiolactone, β-butyrolactone, and δ-valerolactone. Poly-β-alanine (PBA) having a living anionic end-group for a further extension was obtained via HTP of acrylamide. Then, the anionic endgroup on PBA chains was used as initiation sites for AROP of the lactones. By varying acrylamide feeds, a series of copolymers was obtained with a hard segment (β-alanine) content between 6.86 and 36.82 mol%. Elemental analyses and spectral data (MALDI-MS, 1H-NMR, and FT-IR) for all new products were consistent with the proposed structures.

An experimental study on different socket base connections under cyclic loading

Selim Pul,Metin Hüsem,Mehmet Emin Arslan,Sertaç Hamzaçebi 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.3

This paper presents an experimental study on socket base connections of precast reinforced concrete columns. The main purpose of this study is to determine socket base connection which has the closest behavior to monolithic casted column-base joints. For this purpose, six specimens having different column-socket base connection details were tested under cyclic loading. For each test, strength, stiffness, ductility and drift ratios of the specimens were determined. Test results indicated that a suggested connection type is 10% - 30% stronger than the other type of connections under lateral loading. The welded connection (PC-5) had better lateral load carrying capacity and ductility. On the other hand, performance of standard connection (PC-1) which is commonly used in construction was weaker than other connections. Thus, decision of connection type should be referred not only performance but also applicability.

The Impact of the Outcome of Treating a High Anal Fistula by Using a Cutting Seton and Staged Fistulotomy on Saudi Arabian Patients

Bader Hamza Shirah,Hamza Asaad Shirah 대한대장항문학회 2018 Annals of Coloproctolgy Vol.34 No.5

Purpose: A cutting seton is used after a partial distal fistulotomy to treat patients with a high exrasphincteric fistula in ano to avoid fecal incontinence and recurrence. In Saudi Arabia, religious practices necessitate complete cleanness, which makes conditions affecting anal continence a major concern to patients affected by an anal fistula. Therefore, we aimed to evaluate the efficiency of the cutting seton in treating a high anal fistula among Saudi Arabians. Methods: Between January 2005 and December 2014, a prospective study was done for 372 Saudi Arabian patients diagnosed as having a high anal fistula and treated with a cutting seton at Al-Ansar General Hospital, Medina, Saudi Arabia. 0-silk sutures were used. All patients underwent the same preoperative assessment, operative technique, and postoperative follow-up. Weekly, the seton was tightened in outpatient clinics. Results: Two hundred ninety-eight patients (80.1%) were males and 74 (19.9%) females. The duration of symptoms varied from 3–21 months. The fistula healed completely in 363 patients (97.6%); 58 patients (15.6%) reported some degree of incontinence to flatus, but none to feces. In 9 patients (2.4%) the fistula recurred. Conclusion: The utilization of the cutting seton method in the treatment of patients with a high anal fistula is highly efficient as it simultaneously drains the abscess, cuts the fistulous tract, and causes fibrosis along the tract. Treatment of a high anal fistula by using a staged fistulotomy with a cutting seton was very rewarding to Saudi Arabian patients who feared anal incontinence for religious reasons and was associated with low postoperative complication and recurrence rates.

The clinical pattern of intentional injuries at a primary Saudi Arabian trauma center

( Bader Hamza Shirah ),( Hamza Asaad Shirah ),( Ibrahim Abdulaziz Zabeery ),( Osama Abdulqader Sogair ),( Ahmed Medawi Alahmari ),( Wael Awad Alhaidari ),( Maher Hamdan Alamri ),( Waal Nafa Aljabri ) 대한외상학회 2022 大韓外傷學會誌 Vol.35 No.2

Purpose: The term “intentional injuries” refers to a spectrum of injuries resulting from self-inflicted injuries, interpersonal violence, and group acts of violence. Intentional injuries are underreported in Saudi Arabia. This study aimed to analyze and evaluate the characteristics of intentional injuries in patients who presented to the emergency department of a primary trauma center in Medina, Saudi Arabia in 2013. Methods: A prospective cohort database analysis of the clinical patterns and treatment outcomes of 252 patients who had intentional injuries between January and December 2013 was done. Results: The proportion of trauma patients with intentional injuries was 1.3%. The mean age was 34.2±9.4 years, 141 patients (56.0%) were male, and 111 (44.1%) were female (male to female ratio, 1.27:1). The majority (n=159, 63.1%) of injuries occurred at night. Most occurred outside the home (n=180, 71.0%). Financial problems (n=62, 24.6%) and social disputes (n=61, 24.2%) were the most common reasons. Sharp objects (n=93, 36.9%) were the most common weapons used. The head and neck were the most commonly injured areas (n=63, 54.4%). Superficial cuts (n=87, 34.5%), were the most common type of injury. Suturing of wounds (n=54, 21.4%) and surgical debridement (n=47, 18.7%) were the most commonly performed modalities of management. Conclusions: We conclude that intentional injuries in Saudi Arabia are a health care hazard that is, unfortunately, underreported. The clinical pattern is similar in most aspects to international reports but differs in certain features due to the specific religious and conservative characteristics of the community. Nationwide clinical studies are strongly recommended.

Clinical patterns of postcholecystectomy syndrome

Bader Hamza Shirah,Hamza Asaad Shirah,Syed Husham Zafar,Khalid B Albeladi 한국간담췌외과학회 2018 Annals of hepato-biliary-pancreatic surgery Vol.22 No.1

Backgrounds/Aims: Postcholecystectomy syndrome represents a heterogeneous group of symptoms and findings in patients who have previously undergone cholecystectomy. It is rare and under-reported in Saudi Arabia. It can be attributed to many complications such as bile duct injury, biliary leak, retained common bile duct stones, recurrent bile duct stones, and bile duct strictures. In this study, we aimed to analyze the causes and evaluate the approach to postcholecystectomy syndrome in our local Saudi Arabian community because of the vast number of cases encountered in our hospital for gallbladder clinical conditions and its related complications. Methods: A prospective cohort database analysis of 272 patients who were diagnosed and treated for postcholecystectomy syndrome between January 2000 and December 2013 were reviewed. Results: The incidence rate of postcholecystectomy syndrome was 19.8%. The male to female ratio was 1:1.45. The mean age was 37.41±7.12 years. The most common causes were as follows: No obvious cause in 50 (18.4%) patients, Helicobacter pylori infection in 43 (15.8%), pancreatitis in 42 (15.4%), peptic ulcer disease in 41 (15.1%), recurrent common bile duct (CBD) stone in 26 (9.6%), retained CBD stone in 22 (8.1%), bile leakage in 19 (7%), stenosis of the sphincter of Oddi in 12 (4.4%), cystic duct stump syndrome in 11 (4%), and CBD Stricture in 5 (1.8%). The mortality rate was 0%. Conclusions: Any clinical presentation of postcholecystectomy should not be underestimated and be thoroughly investigated. Multidisciplinary collaboration is crucial for the best outcome and a safe approach for all the patients.

Mirizzi syndrome

Bader Hamza Shirah,Hamza Asaad Shirah,Khalid B Albeladi 한국간담췌외과학회 2017 Annals of hepato-biliary-pancreatic surgery Vol.21 No.3

Backgrounds/Aims: The challenging dilemma of Mirizzi syndrome for operating surgeons arises from the difficulty to diagnose it preoperatively, and approximately 50% of cases are diagnosed intraoperatively. In this study, we analysed the effectiveness of diagnostic modalities and treatment options in our series of Mirizzi syndrome. Methods: Patients had a preoperative or intraoperative diagnosis of Mirizzi syndrome, and were classified into three groups: Group 1: Incidental finding of Mirizzi syndrome intraoperatively (n=34). Group 2: Patients presented with jaundice, diagnosed by endoscopic retrograde cholangiopancreatography (n=17). Group 3: Patients diagnosed initially by ultrasound (n=13). Laparoscopic cholecystectomy was conducted in all 49 patients with Cendes type I disease. Partial cholecystectomy, common bile duct exploration, repair of fistula and t-tube placement was conducted on eight patients with Cendes type II and five patients with Cendes type III. Partial cholecystectomy with Roux-en-Y hepaticojejunostomy was conducted in two patients with Cendes type IV disease. Results: Sixty-four patients were diagnosed with Mirizzi syndrome. Morbidity rate was 3.1%. Mortality rate was 0%. Group 3 (patients diagnosed initially by ultrasound) had the best treatment outcome, the least morbidity, and the shortest hospital stay. Conclusions: Suspected cases of Mirizzi syndrome should not be underestimated. Difficulty in establishing preoperative diagnosis is the major dilemma. As it is mostly encountered intraoperatively, the approach should be careful and logical to identify the correct type of Mirizzi by a thorough diagnostic laparoscopy and thus, provide optimum treatment for the subtype to achieve the best outcome.

Predictive factors for gangrene complication in acute calculous cholecystitis

Bader Hamza Shirah,Hamza Asaad Shirah,Muhammad Adnan Saleem,Mohammad Azam Chughtai,Mohamed Ali Elraghi,Mohamed Elsayed Shams 한국간담췌외과학회 2019 Annals of hepato-biliary-pancreatic surgery Vol.23 No.3

Backgrounds/Aims: Gallbladder gangrene is a grave complication of acute calculous cholecystitis that is difficult to detect preoperatively. Ultrasound could show a gallbladder wall that is more thickened. In addition, other clinical measures were reported to be possible predictive factors. Therefore, we aim in this study to evaluate the gallbladder wall thickness measured by ultrasound and other clinical measures as predictive factors for gangrene complication in acute calculous cholecystitis. Methods: A prospective cohort database analysis of the results of 674 patients diagnosed and treated for acute calculous cholecystitis between January 2010 and December 2014 was done. Patient’s inclusion criteria were acute calculous cholecystitis in adults who were operated within three days of onset of symptoms. Results: 117 (17.4%) patients had gangrene. Gallbladder sonographic wall thickness 5.1-6 mm, more than 6 mm, male gender, diabetes mellitus, leukocytosis ˃15,000 cells/ml, and age ≥40 years were found to be factors predisposing to gangrene complicated acute calculous cholecystitis that represented a statistically significant difference (p≤0.01). Conclusions: We conclude that gallbladder sonographic wall thickness 5.1-6 mm, more than 6 mm, male gender, diabetes mellitus, leukocytosis ˃15,000 cells/ml, and age ≥40 years were found to be factors predisposing to gangrene complicated acute calculous cholecystitis that represented a statistically significant difference. By implementing these risk factors, patients urgency for surgery can be decided in the emergency department. Other risk factors such as high alanine aminotransferase, elevated aspartate aminotransferase, and high alkaline phosphatase could be of help in the decision for early operation.

Optimal torso design selection for dual 7-DOF robot arm using von Mises stress and workspace analysis

Hamza Khan,Saad Jamshed Abbasi,이민철 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

This paper presents a unique optimal torso design selection technique for the dual seven-degree-of-freedom robot arm. This optimal design enhances the robot endeffector's workspace with less operational stress. The selection procedure incorporates the von Mises stress and robot workspace analysis in different robot-torso mounting configurations. The torso design selection strategy includes the von Mises stress calculation numerically and by using SolidWorks static analysis for robot arm considered as bolted-fixed end cantilever beam. Followed by robot end-effector workspace analysis using inverse kinematics, which determines the maximum area covered by manipulated robot end-effector in 2-dimensional (2D) and 3-dimensional (3D) space. Subsequently, introducing a selection function for torso design. This selection function is calculated based on weighting coefficients (priority given to stress and workspace), von Mises stress, and workspace area. The selection technique concludes that the torso design with upper-arm mounting configuration is optimal for current robot application, i.e., assembly.

Robust Position Control of Assistive Robot for Paraplegics

Hamza Khan,Saad Jamshed Abbasi,Karam Dad Kallu,Hyun Hee Kim,Young-Jun An,Min Cheol Lee 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.11

Paraplegia refers to the paralysis of the lower limbs resulting from the damage to the spinal cord. Thus far, considerable efforts have been devoted to the rehabilitation of paraplegics and the improvement of their qualityof life. This study focuses on the position control of the sit–stand mechanism of an assistive robot developed to aid paraplegics in shifting from a sitting to a standing position and vice versa. Two control techniques for the modelwere proposed: sliding mode control (SMC) and SMC integrated with a sliding perturbation observer (SMCSPO). The control algorithm was designed and implemented in MATLAB/Simulink. The simulation results indicate thatthe SMC is a nonlinear control; however, because the robot is a highly nonlinear model, which requires a high switching gain, the controller introduces chattering into the system. The SMC has been observed to exhibit inadequate performance when controlling a system with uncertainties. In contrast, the SMCSPO is a robust nonlinear control integrated with a nonlinear compensator, which performs better than the SMC even in the presence of external disturbances.

Feedback Control of Sit-Stand Mechanism of an Assistive Device for Paraplegics

Hamza Khan,Saad Jamshed,Karam Dad Kallu,Min-Cheol Lee 제어로봇시스템학회 2019 제어로봇시스템학회 국내학술대회 논문집 Vol.2019 No.5